Title of Invention	METHOD TO PROCESS LEAD-BEARING MATERIALS
Abstract	The invention is relative to non-ferrous metallurgy, mainly to methods to process lead-bearing materials. The task of the invention is to increase lead recovery into lead bullion and specific capacity of the process at simultaneous reduction of specific consumption of energy carriers. The method includes charge preparation and drying, charge roasting-smelting in suspended state in oxygen atmosphere with production of oxide melt and mixture of dusts and roasting-smelting gases, reduction of melt at its filtration through the layer of warmed-up particles of carbon reductant with production of metallic lead, zinc-bearing oxide melt and gases. Charge is undergone granulation and classification and to the stage of roasting-smelting isolated fraction of dry charge is supplied, no less than 90% of its mass is composed from particles with the grain size of 0.01-0.10 mm. Thereby, free moisture content in charge at the stage of its preparation amounts to 8-16% and as carbon reductant there is used coal with the content of total carbon in dry mass from about 49 to about 80% and volatiles from about 11 to about 27%.

Title of Invention

METHOD TO PROCESS LEAD-BEARING MATERIALS

Abstract

The invention is relative to non-ferrous metallurgy, mainly to methods to process lead-bearing materials. The task of the invention is to increase lead recovery into lead bullion and specific capacity of the process at simultaneous reduction of specific consumption of energy carriers. The method includes charge preparation and drying, charge roasting-smelting in suspended state in oxygen atmosphere with production of oxide melt and mixture of dusts and roasting-smelting gases, reduction of melt at its filtration through the layer of warmed-up particles of carbon reductant with production of metallic lead, zinc-bearing oxide melt and gases. Charge is undergone granulation and classification and to the stage of roasting-smelting isolated fraction of dry charge is supplied, no less than 90% of its mass is composed from particles with the grain size of 0.01-0.10 mm. Thereby, free moisture content in charge at the stage of its preparation amounts to 8-16% and as carbon reductant there is used coal with the content of total carbon in dry mass from about 49 to about 80% and volatiles from about 11 to about 27%.

Full Text	Method to process lead-bearing materials Technical field The invention is relative to non-ferrous metallurgy, mainly to methods to process lead-bearing materials of different origin. There is an extensive group of lead-bearing materials such as hydrometallurgical processes residues, converting dusts of copper mattes, slurries of neutralization and process solutions purification that are not processed or processed in insufficient volume by well-known methods, so they are accumulated in dumps. In addition to lead, these materials contain considerable amount of zinc and copper that reduces recovery complexity of non-ferrous metals from natural mineral raw material in processes of its metallurgical processing. Simultaneously, the storage of lead-bearing materials causes complicated ecological problems. Thus, the range extension of processed lead-bearing materials represents an actual task for the technology and environment protection. Prior art There is known the method to process lead-bearing materials with increased sulphates content and oxides content like lead residues, dusts, battery paste, and others in the mixture of finely grained lead concentrates, recycle dusts, fluxes, coal dust - QSL-technology, based on the principle of bubbling smelting (Mager K., Shulte A. "Production and technological aspects of the first four QSL-plants". Proceedings of International Symposium on processing of primary and secondary lead. Halifax, Nova Scotia, Canada, August 20-24, 1989, Pergamon Press Publisher, New York, p. 15-26). The method lies in the fact that indicated mixture is granulated and resulted wet grains are fed on the surface of oxide melt, that contains from 35-60% of lead in the form of oxides. This oxide melt and the layer of metallic lead located under it are blown through by oxygen-containing gas. As a result of interaction between raw material sulphides with lead oxides at the temperature of 850-950°C lead bullion is formed that is partly transferred to oxide melt as a result of its oxidizing using oxygen-containing gas. By grains feed control and consumption of oxygen-containing gas there is achieved constant high concentration of lead oxides in slag and predominance of speed of lead bullion formation over the speed of its oxidizing using oxygen-containing gas. Resulting oxide melt with the temperature of no more than 950°C continuously goes to reduction area, where as the slag goes towards the outlet, melt temperature gradually increases up to 1150-1250°C at the expense of gas heating. Simultaneously with it lead oxides reduction up to lead bullion is realized by means of blowing of the melt by mixture of air and powdered or gaseous carbon material (coal, natural gas and others). The disadvantage of the known method is low direct recovery of lead into lead bullion, low specific capacity of the process and simultaneously high specific consumption of energy carriers (oxygen-containing gas, carbon materials). It is caused by the fact that the reduction of lead concentration in oxide melt leads to the necessity of increasing the temperature of this melt during oxidizing and reducing stages of the process, and, correspondingly, to the increase of lead output into smelting dusts (up to 50% and more from its mass in charge). During processing of lead-bearing materials with lead concentration less than 30% and iron oxidation rate more than 50-60%, the smelting process is almost destroyed due to viscous oxide melt formation, inapplicable for gas blowing. There is also known the method to process lead-bearing materials with increased portion of sulphates and oxides like lead residues, dusts, battery paste, and others in the mixture of sulphide lead concentrates, recycle dusts, fluxes, coal dust - Ausmelt technology, based on bubbling smelting principle (Mounsey E.N., Piret N.L. "A review of Ausmelt technology for lead smelting". Proceedings of the Lead-Zinc 2000 Symposium. Pittsburgh, USA, October 22-25, 2000, p. 149-169). The method lies in the fact that mentioned well averaged mixture in finely grained or granulated form with lead concentration from 25-60% is fed on the surface of oxide melt. From above oxygen-containing gas is blown into oxide melt volume and at the deficit of the process heat balance there is also blown powdered, liquid and gaseous carbon fuel. As a result of interaction between raw material sulphides with lead oxides at the temperature of 1000-1100°C lead bullion is formed that is partly transferred to oxide melt as a result of its oxidizing using oxygen-containing gas. By charge feeding control and consumption of oxygen-containing gas there is achieved constant high concentration of lead oxides in slag and predominance of speed of lead bullion formation over the speed of its oxidizing using oxygen-containing gas. Resulting oxide melt with the temperature that is not higher than 1100°C is transferred to reduction process stage in continuous or intermittent mode or is tapped and granulated for further processing of solid lead slag at reduction stage with production of lead bullion. Lead oxides reduction to lead bullion from rich lead slag of oxidizing process stage is realized by means of melt blowing by the mixture of air and powdered, liquid or gaseous carbon material (coal, mazut, natural gas and others). Significant increase of energy carriers consumption with the accompanying increase of the temperature of oxide melt allows to transfer this process from the mode of lead bullion smelting into the mode of lead (and partly of zinc) fuming into smelting dusts, those can be then processed separately by this very method with the production of lead bullion. Disadvantages of the well-known method are low lead recovery into lead bullion, low specific capacity of the process and simultaneously high consumption of energy carriers (oxygen-containing gas, carbon materials). The closest technical substance is in the method to process lead-bearing materials, such as lead and zinc residues, converting dusts, slurries of hydrolytic purification of process solutions that contain mainly simple or compound sulphates and metals oxides, including thermally stable sulphates (of lead, calcium) and higher iron oxides (Patent RK #9, C 22 B 13/02,1997). According to this method the preparation of wet charge is realized from primary lead-bearing materials and fluxes with introduction in it as a reductant for powdered sulphide material up to mass ratio of total amounts of sulphide, elementary and pyrites sulphur to the total sulphur content in charge from 0.08 to 0.87 and/or powdered carbon material at the rate from 4 to 12 kg of pure carbon per 100 kg of ferric iron and from 20 to 140 kg of pure carbon per 100 kg of sulphate sulphur. Thereby, powdered carbon material is introduced with the activation energy of carbon gasification reaction in the range of 56-209 kJ/mol. As powdered carbon material there are used lead sulfide concentrates or lead (polymetallic) ore. Produced wet charge with recommended moisture content from 2 to 16% is dried up to the residual moisture content of less than 1%. Dried charge is transferred to roasting-smelting stage in suspended state in oxygen-containing gas atmosphere with the production of dispersed oxide melt and the mixture of dusts and roasting-smelting gases. Dispersed oxide melt produced at the stage of roasting-smelting, is reduced by means of its filtration through the layer of warmed-up particles of crushed carbon material (coke or coal) with the grain size of 2-50 mm with the production of lead bullion, zinc-bearing slag depleted by lead and gases mixing with roasting-smelting gases. Dusts are separated from the mixture of reaction gases and returned to the stage of roasting-smelting. At the stage of wet charge preparation, under conditions of careful blending of materials containing natural binding compounds (soluble salts, metals hydroxides and hydrates, gypsum) and in the presence of free moisture in charge that is no less than 2% there is occurred its structuring with the formation of "complex" microconglomerates from inhomogeneous particles, including both oxidized components (sulphates and metals oxides) and reagent-reductants (metals sulphides and carbon). Bonds formed between inhomogeneous particles in microconglomerates at the stage of wet charge preparation are strengthened at the stage of charge drying. It provides thermal stability of microconglomerates particles under conditions of quick heating of dry powdered charge at the stage of roasting-smelting. The presence of close contact of sulphate and oxide components with sulphides and carbon in microconglomerates volumes provides significant speed-up of charge desulphurization process and decomposition of iron higher oxides at the stage of roasting-smelting of powdered charge in suspended state at temperatures of 1250-1350°C. The speed-up of the decomposition process of sulphates and iron higher oxides at temperatures that 300-500°C less than the temperatures of their thermal decomposition is stipulated by the intensive flow of chemical interaction of the following type in microconglomerates volumes of inhomogeneous particles: Me'SO4 + Me2S -» Me'O(Me') +Me2O(Me2) + SO2; (1) Me'O + Me2S -» Me'CKMe1) +Me2O(Me2) + SO2; (2) Fe2O3 + MeS -* Fe3O4 + MeO + SO2; (3) Fe3O4 + MeS -» FeO + MeO + SO2; (4) MeSO4 + C -» MeO(Me, MeS) + CO2 + SO2; (5) MeO + C ^ Me + CO; (6) Fe2O3 + C -> Fe3O4 + CO; (7) Fe3O4 + C -+ FeO + CO. (8) Disadvantages of the known method are low recovery of lead into lead bullion, low specific capacity of the process and at the same time high specific consumption of energy carriers (oxygen-containing gas, carbon materials and electric power). Stated disadvantages are determined by the fact that the known method does not provide sufficiently high content and optimal sizes of thermally stable "complex" microconglomerates in dry charge, supplied for roasting-smelting stage in suspended state. These both factors are stipulated by uncontrolled process of adhesion or disintegration of microconglomerates particles at the stage of wet charge drying. At moisture of charge, that is supplied for drying stage, amounting to 2-7%, independently of the content of binding components in it, there is no enough free moisture to form bonds between particles, that are sufficient for mechanical and thermal stability of formed microconglomerates. It leads to disintegration of mechanically unstable microconglomerates and to decrepitation of thermally unstable microconglomerates at the stages of charge drying and roasting-smelting. As a result there is the decrease of "complex" microconglomerates particles content and the increase of mass portion of individual dispersed particles in charge at the stage of roasting-smelting. At higher moisture content of charge supplied for drying stage, the amount of free moisture is enough for formation of considerable number of stable bonds between particles. However, uncontrolled particles adhesion in the process of material drying leads to the formation of coarse-grain structure of dry charge with the possible formation of extremely large lumps of adhered particles, the roasting-smelting of which in suspended state is impossible without their additional granulation. Both low content of thermally stable "complex" microconglomerates in dry charge, supplied for the stage of roasting-smelting and their extremely large sizes noticeably reduce the efficiency of processing of lead-bearing materials with increased portion of sulphates, iron higher oxides and zinc oxides by means of the known method. Low portion of "complex" microconglomerates in dry charge reduces the contact degree between inhomogeneous particles-reagents, and large sizes of microconglomerates decrease the rate of their heating at the stage of charge roasting-smelting. Both factors lead to the intensity reduction of low temperature interactions between charge components according to reactions (l)-(8) and stipulate the necessity to increase the temperature of roasting-smelting up to 1400-1450°C for more complete decomposition of thermally stable sulphates and the increase of fluidity of oxide melts with increased content of iron higher oxides. Increased temperatures of roasting-smelting lead to relatively high specific consumptions of powdered carbon fuel and oxygen for its oxidizing and to considerable increase of recycle dusts output, thereby preventing the reduction of iron higher oxides content in dispersed oxide melt. Viscosity of oxide melts, saturated with iron higher oxides, is increased while there is reduction of lead oxide in the layer of crushed carbon material. As a result, there is the rise of slowdown effect of the filtration process and of oxide melt reduction, worsened by considerable heat absorption for iron higher oxides reduction. Maintenance of high fluidity and the increase of oxide melt reduction degree under these conditions requires heat input or reduction of oxide melt supply to the process of reduction stage. Thus, the known method does not provide effective realization of low temperature interactions of charge components at the stage of roasting-smelting and further effective reduction of oxide melts in the layer of crushed carbon reductant. Thereby, one of the most significant factors of reducing efficiency of the known method is underestimated lower limit of recommended range of free moisture content in wet charge, supplied for drying procedure. Additional factors of reduced efficiency of the known method might be the use of recommended carbon materials for the formation of the layer of crushed carbon reductant. The use of coke having the lowest reaction capacity in a number of carbon materials stipulates relatively low rate of reduction of oxide melt during its filtration through the layer of crushed reductant, limiting by this the specific capacity of the process. To increase the rate of reduction there is required the increase of oxide melt temperature. However, the increase of its temperature at the stage of charge roasting-smelting leads not only to the increase of specific consumption of energy carriers (powdered fuel and oxygen for its burning), but also to the decrease of lead recovery into lead bullion at the expense of increase of degree of lead transfer into roasting-smelting dusts. Thereby, the increase of recycle dusts portion in charge might reduce the specific capacity of the process in higher degree than the increase of oxide melt temperature at the stage of roasting-smelting allows its increasing. Reaction capacity of coal is higher than that of coke. However, in contrast with coke, not all coals possess thermal stability under conditions of quick heating and when they get onto the surface of slag bath they might decrepitate. Thereby, the layer permeability of crushed carbon reductant for dispersed oxide melt is significantly reduced or completely destroyed. Correspondingly, there is decreased the surface and the rate of reduction reactions flow. It leads to corresponding decrease of lead recovery into lead bullion and of specific capacity of the process (up to its complete failure). Moreover, the need to increase fluidity and, correspondingly, the temperature of oxide melt at the decrease in the layer permeability of crushed reductant stipulates the increase of energy carries specific consumption that is unavoidable in this case. As the basis for this invention there was put the task to change the known method of processing of lead-bearing materials with increased concentration of thermally stable sulphates and iron higher oxides thus in order to increase lead recovery into lead bullion and specific capacity of the process at simultaneous reduction of energy carriers specific consumption. Abstract of the disclosure The assigned task is achieved by the fact that in the method to process lead-bearing materials that includes charge preparation by means of thorough blending of wet sulphide and oxidized lead-bearing materials with fluxes and powdered carbon material at which mass ratio of total amount of sulphide, elemental and pyrites sulphur to total sulphur content in charge amounts to 0.08-0.87 and powdered carbon material having activation energy of carbon gasification reaction within the range of 56-209 kJ/mol is introduced as reductant on the basis of 4-12 kg of pure carbon per 100 kg of ferric iron and 20-140 kg of pure carbon per 100 kg of sulphate sulphur in charge; drying of produced wet charge up to residual moisture content less than 1%; roasting-smelting of dry charge in suspended state in oxygen atmosphere with the production of dispersed oxide melt and the mixture of dusts and roasting-smelting gases; reduction of dispersed oxide melt at its filtration through the layer of warmed-up particles of crushed carbon reductant with the grain size of 2-50 mm with the production of metallic lead, zinc-bearing oxide melt and gases, mixing with dusts and gases of roasting-smelting; separation of produced mixture of dusts and reaction gases with return of dusts to the stage of roasting-smelting, dry charge is undergone granulation and classification, and to the stage of roasting-smelting isolated fraction of dry charge is supplied, no less than 90% of its mass is composed from particles with the grain size of 0.01-0.10 mm. It is advisable that the content of free moisture in charge at the stage of its preparation was 8-16%. It is reasonable that as carbon reductant to the stage of dispersed oxide melt reduction there was supplied coal with the content of total carbon in dry mass from about 49 up to about 80% and of volatiles from about 11 up to about 27%. The method to process lead-bearing materials includes charge preparation by means of thorough blending of wet sulphide and oxidized lead-bearing materials with fluxes and powdered carbon material at which mass ratio of total amount of sulphide, elemental and pyrites sulphur to total sulphur content in charge amounts to 0.08-0.87 and powdered carbon material having activation energy of carbon gasification reaction within the range of 56-209 kJ/mol is introduced as reductant on the basis of 4-12 kg of pure carbon per 100 kg of ferric iron and 20-140 kg of pure carbon per 100 kg of sulphate sulphur in charge; drying of produced wet charge up to residual moisture content less than 1%; roasting-smelting of dry charge in suspended state in oxygen atmosphere with production of dispersed oxide melt and the mixture of dusts and roasting-smelting gases; reduction of dispersed oxide melt at its filtration through the layer of warmed-up particles of crushed carbon reductant with the grain size of 2-50 mm with production of metallic lead, zinc-bearing oxide melt and gases mixing with dusts and gases of roasting-smelting of dry charge; separation of produced mixture of dusts and reaction gases with return of dusts to the stage of roasting-smelting of dry charge, differing by the fact that dry charge is undergone granulation and classification, and to the stage of roasting-smelting isolated fraction of dry charge is supplied, no less than 90% of its mass is composed from particles with the grain size of 0.01-0.10 mm. The achievement of the assigned task at realization of proposed solutions is provided by the following factors: - formation of charge microstructure with high portion of mechanically and thermally stable microconglomerates of inhomogeneous particles, including sulphate, oxide, sulphide and carbon components; - stabilization of optimum fraction composition and microstructure of dry charge, supplied to the stage of roasting-smelting in suspended state; - intensification of low temperature interactions of sulphate and oxide components with sulphides and carbon at the stage of charge roasting-smelting in suspended state; - oxide melt reduction intensification at the stable maintenance of porous structure and permeability of crushed carbon reductant layer. By morphological researches of charge there was found out that minimum size of "complex" microconglomerates of inhomogeneous particles amounts to about 0.01 mm. More dispersed charge fractions comprise separate, non-associated particles or microconglomerates from single-type highly dispersed particles of lead-bearing materials, possessing increased adhesive properties (such as dust, residues, slurries). From analyses of results of experimental smelting it is known that the increase of portion of fine fractions with particles grain size less than 0.01 mm as well as the increase of coarse fraction portion with individual and associated particles having grain size of more than 0.1 mm in dry charge lead to reduction of rate and degree of its components transformation at the stage of roasting-smelting in suspended state and prevent the achievement of the assigned task. Negative effect on indices of the process of increased portion of fine and coarse fraction in dry charge material is successfully eliminated by means of introduction of successive operations of granulation and classification of dry charge before its supply to the stage of roasting-smelting. The combination of granulation and classification operations provides the production of isolated fraction of dry charge, no less than 90% of particles mass of which is in the range of 0.01-0.10 mm, that allows: - to keep in dry charge after its grinding microconglomerates of inhomogeneous particles, including sulphate, oxide, sulphide and carbon components; - to limit the entry of excessively fine (less than 0.01 mm) and excessively coarse (more than 0.10 mm) individual particles and microconglomerates going to the stage of roasting-smelting, that prevent the increase of charge desulphurization degree and decomposition of iron higher oxides at the stage of charge roasting-smelting at reduced temperature modes of the process. Thereby, the stabilization of fraction composition of dry charge within the range of prevailing particles grain size of 0.01-0.10 mm allows effective solution of the assigned task. Increased direct recovery of lead into lead bullion, the increase of specific capacity of the process and simultaneous reduction of specific energy consumption are achieved thereby at the expense of: - prevention of poor matte formation; - decrease of dust entrainment and the portion of smelting recycle dusts in charge; - increase of the degree of lead reduction from fluid oxide melt in the layer of crushed carbon material; - decrease of consumption of powdered carbon fuel and of oxygen for its burning and electric power for compensation of heat losses in reduction reactions of iron higher oxides in the layer of carbon reductant. The decrease of lower limit of dry charge particles grain size less than 0.01 mm reduces the degree of low temperature interactions flow of its components at the stage of roasting-smelting in reactions (l)-(8) because of decrease of "complex" microconglomerates portion in charge. It stipulates the necessity to increase the temperature of the process. Moreover, there is the increase of mechanical carry over of fine particles into roasting-smelting dusts. In the aggregate it leads to the decrease in lead recovery into lead bullion, the decrease of specific capacity of the process and increase of specific consumption of energy carriers. The increase of upper limit of dry charge particles grain size less than 0.01 mm reduces the degree of low temperature interactions flow of its components at the stage of roasting-smelting at the expense of the rate reduction of coarse particles heating and the decrease of total reaction surface of components, that also stipulates the necessity to increase the temperature of the process and prevents from the achievement of the assigned task. The decrease of mass portion of particles with the grain size from 0.01 up to 0.10 mm in dry charge that is less than 90%, as in the case of change of limits of optimal rage of particles grain size, results in the degree reduction of low temperature interactions flow of its components at the stage of roasting-smelting. It can happen either at the expense of the decrease of "complex" microconglomerates portion or at the expense of the increase of extremely coarse individual particles and microconglomerates in charge. Both factors stipulate the necessity to increase the process temperature. As a result, there is the decrease of lead recovery into lead bullion and of specific capacity of the process and specific consumption of energy carriers is increased. According to the patented method, thorough blending of materials at the stage of wet charge preparation is required to conduct at free moisture content in charge mixture amounting to 8-16%. On the basis of experimental data it allows: 1) to form charge homogeneous microstructure with large portion of "complex" microconglomerates of inhomogeneous particles, including sulphate, oxide, sulphide and carbon components; 2) to form sufficient number of stable bonds between inhomogeneous particles, providing thermal stability of "complex" microconglomerates at the stage of dry charge roasting-smelting. The mentioned range of free moisture content is optimal, because it provides the most significant increase of "complex" microconglomerates portion in charge at the stage of its preparation and strengthening of these microconglomerates at the stage of wet charge drying. At free moisture content of less than 8% there is decrease of "complex" microconglomerates portion in wet charge, supplied for charge drying, as well as the decrease of mechanical and thermal stability of such microconglomerates in dry charge. It reduces the degree of charge components interactions flow at the stage of roasting-smelting and leads to deterioration of process indices within the framework of the assigned task. At free moisture content of 8% and more "complex" microconglomerates portion in wet charge, supplied for charge drying is noticeablely increased. There is also the increase of mechanical and thermal stability of such microconglomerates in dry charge. In spite of the fact that in this case as well as in prototype there is uncontrolled adhesion of particles at the stage of drying, the use of successive operations of granulation and classification of dry charge in the patented method excludes entering of its extremely coarse fractions to the stage of roasting-smelting. Thereby, there is provided the possibility of maximum effective process conducting. The increase of free moisture content in charge more than 16% is unpractical because does not lead to noticeable increase of "complex" microconglomerates portion in dry charge at the stage of roasting-smelting and, correspondingly - to increase of the process indices within the framework of the assigned task. At the same time, evaporation of moisture excess requires the increase of fuel consumption for charge drying, i. e. increases total specific consumption of energy carriers. As crushed carbon reductant of dispersed oxide melt from the stage of charge roasting-smelting in the prototype there is suggested coke or coal. Due to the presence of active hydrocarbons (volatiles) and much less activation energy of solid carbon gasification reaction, coal usually possesses higher reduction capacity in comparison with coke. However, in contrast with coke, not all kinds of coal possess thermal stability and under conditions of quick heating they might decrepitate on the surface of slag bath, that is not taken into consideration in the prototype. At the same time, decrepitation of coal might not only reduce the degree of oxide melt reduction in the layer of carbon reductant dramatically but completely disturb the flow of reduction process. Thermal stability of coal is directly connected with its caking capacity during calcination. The more caking capacity of coal the higher its thermal stability is. On the basis of this interrelation and the analysis of experimental data, there was determined optimal range of coals quality, possessing thermal capacity that is higher enough. According to the patented method, as crushed carbon reductant there is reasonable to use coal with the content of total carbon in dry mass from about 49% up to about 80% and volatiles - from about 11% up to about 27%. The use of coal with the stated range of total carbon and volatiles content as crushed carbon reductant enhances the effectiveness of the process reduction stage at the expense of the increase of reductant activity at keeping of developed reaction surface and high permeability of crushed reductant layer for dispersed oxide melt. It allows additional increase of lead recovery into lead bullion and of specific capacity of the process without oxide melt temperature rise, providing by that additional economy of specific consumption of energy carriers. On the one hand, total carbon in coal dry mass comprises of solid carbon and volatiles carbon and on the other hand, solid carbon and volatiles comprise the basis of coal dry mass. Thereby, recommended ranges of total carbon and volatiles content in coal dry mass are closely connected and therefore, it is reasonable to consider them together. At reduction of total carbon content in coal dry mass less than 52% and at accompanying increase of volatiles content in that mass more than about 27%, coal caking capacity at calcination and its thermal stability under conditions of quick heating are noticeably decreased. The increase of decrepitation degree of crushed carbon lumps on the surface of slag bath reduces permeability of carbon reductant layer. As a result, interdependently there is reduced oxide melt reduction rate, the degree of lead recovery into lead bullion and specific capacity of the process. Moreover, the decrease of the process reduction stage intensity leads to the increase of energy carriers specific consumption stipulated by the necessity to increase fluidity and, correspondingly, oxide melt temperature as well as compensation of increasing heat losses for its reduction and settling. At increased content of solid carbon in coal dry mass more than about 80% and accompanying reduction of volatiles content in this mass less than about 10%, coal caking capacity at its calcination and its thermal stability under conditions of quick heating are also noticeablely decreased. It is determined by optimal nature of coals calcination stipulated by the presence in their content of bituminous substances - products of transformation of waxes, resins and fatty substances contained in plants-coal creators. Portion of such substances is reduced in coals with low degree of metamorphism - lignites as well as in coals with high degree of metamorphism - antracites. Dependence of coals caking capacity on their content in dry mass of total carbon and volatiles, represented in standard units, given on Figures 1 and 2. From presented data it is seen that coals recommended in patented method, containing total carbon in dry mass from about 49% up to about 80% and of volatiles from about 11% up to about 27% possess the highest degree of caking capacity. The reduction of caking capacity and coal thermal stability, as described above, leads to deterioration of the process indices within frameworks of the assigned task. The method is realized in the unit, the principal scheme of which is represented on Figure 3. The unit consists of the vertical reaction shaft 1 of rectangular cross-section in the roof of which there is installed the burner 2 to supply charge, oxygen, recycle dusts and crushed carbon reductant; the vertical partition wall 3 water cooled copper elements separating the reaction shaft 1 from the gas exhaust shaft 4 with keeping of gas clearance above slag bath to withdraw reaction gases; the electric furnace 5 adjacent to the smelting chamber and separated from it by the vertical partition 6 submerged into slag bath and having water cooled copper elements; the hearth 7 common for the reaction shaft 1, the electric furnace 5 and the gas exhaust shaft 4; the jacketed belt 8 and facilities to tap smelting products 9. The method is realized by the following way. Using chemical analysis data for lead-bearing materials, that might be lead concentrates, dusts, residues and slurries of hydrometallurgical production, battery pastes, refining recycles of lead bullion and other materials, proportions are calculated and materials are blended in such ratio at which mass ratio of total amount of sulphide, elemental and pyrites sulphur to the total content of sulphur in charge amounts to 0.08-0.87. To the produced mixture of wet lead-bearing materials there are added fluxes (limestone, quartz sand and suchlike) and powdered carbon reductant. As powdered carbon reductant there might be used different coal types (lignites, coal and charcoal), coal concentrates, produced from clinker after Waelz processing, wastes of coke production and others. To achieve optimal combination of areas of heat release and absorption in reactions of charge components transformation at the stage of roasting-smelting it is reasonable to introduce in it powdered carbon materials with activation energy of carbon gasification reaction within the range of 56-209 kJ/mol. The addition of powdered carbon material is realized at the rate from 4 to 12 kg of pure carbon per 100 kg of ferric iron and from 20 to 140 kg of pure carbon per 100 kg of sulphate sulphur in charge. Produced charge with free moisture content in it of 8-16% is undergone homogenization by means of thorough blending of materials. It allows forming homogeneous microstructure of charge with large portion of "complex" microconglomerates of inhomogeneous particles, including sulphate, oxide, sulphide and carbon components. At free moisture content in charge less than 8% it is required firstly to wet charge up to this minimal level and then to conduct its homogenization. At free moisture content in charge more than 16% it is required firstly to conduct its homogenization and then to remove the excess of free moisture (for example, by means of filtration of material) in order to avoid excessive consumption of fuel necessary for charge drying. Wet homogenized charge is supplied for drying, where it is dried up to moisture residual content of less than 1%. Produces dry charge, containing coarse fractions of adhered particles, is undergone granulation, and granulated powdered material - classification. Coarse fraction of dry powdered charge with prevailing particles grain size more than 0.10 mm is returned for granulation, dispersed fraction with prevailing particles grain size less than 0.01 mm is returned to the stage of wet charge preparation and fraction, no less than 90% of mass of which is composed from particles with the grain size of 0.01-0.10 mm - to the stage of roasting-smelting. It provides conservation of dry powdered charge, supplied to the stage of roasting-smelting, considerable portion of thermally stable "complex" microconglomerates, formed at stages of preparation and wet charge drying. At insufficient calorific capacity of dry charge the necessary amount of powdered carbon fuel is introduced into it. As such fuel there might be used the same powdered carbon material that is introduced into wet charge as reductant for iron higher oxides and sulphates at the stage of its preparation or other powdered carbon material having high calorific power. Before supplying to the stage of roasting-smelting in charge there are introduced the process recycle dusts and crushed carbon reductant with the grain size of 2-50 mm, the most preferable grain size is 5-20 mm. As crushed carbon reductant there might be used different carbon materials - coal coke or petroleum coke, clinker after Waelz processing, charcoal and others. However, according to the patented method it is more preferable to use as crushed carbon reductant coal in dry mass of which there are contained from about 49 up to about 80% of total carbon and from about 11 up to about 27% of volatiles. Coals of such quality possess sufficiently high caking capacity and thermal stability, allowing to form stable porous structure of crushed carbon reductant with developed reaction surface and high permeability for reduction of oxide melt. Due to the presence of active hydrocarbonic component and reduced activation energy of carbon gasification reaction, such coals are more active carbon reductant than carbon materials, that passed thermal processing (cokes). Dry powdered charge together with powdered carbon fuel (if necessary), recycle dusts and crushed carbon reductant is supplied through the vertical burner 2 into the reaction shaft 1 for roasting-smelting in suspended state in the atmosphere of oxygen-containing gas. Oxygen consumption is determined at the rate of full degree of desulphurization and oxidation of sulphides of lead, zinc and iron up to oxides and carbon fuel up to carbon dioxide and water steams with the deduction of metals sulphates consumption and iron higher oxides for reactions of interaction with sulphide, elemental and pyrites sulphur and carbon of powdered carbon reductant according to stoichiometry of total reactions: 3Me1SO4 + Me2S -» SMe'O +Me2O + 4SO2; (9) 3Fe2O3 + MeS -> 6FeO + MeO + SO2; (10) 2MeSO4 + C -» 2MeO + CO2 + 2SO2; (11) 2Fe2O3 + C -* 4FeO + CO2. (12) In other words, oxygen consumption is reduced by the value determined by the amount of oxygen, "connected" in sulphates and iron higher iron oxides. Moreover, for oxidizing of pure carbon of carbon reductant oxygen is not introduced. Under the influence of high temperatures in reaction shaft powdered charge is ignited, warmed up very quickly up to the temperatures of 1250-13 50°C at the expense of oxidizing by oxygen of gas phase of part of sulphides and powdered carbon material. Thereby, in volumes of "complex" microconglomerates of particles in temperature areas of 350-700°C intensive interactions of sulphates and metal oxides (including iron higher oxides) with sulphides and carbon flow. As a result there is formed dispersed oxide melt with reduced content of iron higher oxides that possesses high fluidity and the mixture of dusts and sulfur dioxide reaction gases. Crushed carbon reductant, supplied together with charge, due to large grain sizes of lumps (mainly 5-20 mm) as well as due to quick reduction of oxygen concentration in gas phase by the height of the reaction shaft 1 (above the heel of slag bath the concentration of oxygen amounts to about 1-2%) has no time to burn in the reaction shaft 1 and forms porous, continuously refilling reductive layer from greatly warmed up lumps of carbon material on the surface of slag bath under the burner 2. Dispersed oxide melt produced during charge roasting-smelting is filtered through this layer of crushed carbon reductant. Thereby, lead oxides are reduced up to metal, iron higher oxides - up to wustite and zinc oxides have no time to reduce in noticeable degree and together with wustite and fluxing components form zinc slag depleted by lead. Copper oxides as well as lead oxides are reduced in the layer of carbon reductant up to metal and transfer into lead bullion and non-ferrous metals sulphides, presenting in dispersed melt of roasting-smelting, are distributed between metallic and slag phases (at charge desulphurization degree more than 90-94%) or form dispersed matte phase. Gaseous products of reduction reactions (CO, CC>2 and zinc steams) go out from the layer of carbon reductant and mix with gases and roasting-smelting dusts. Zinc slag depleted by lead containing dispersed suspended material of metallic lead (and matte, if such is formed) flows into the electric furnace 5 adjacent with the reaction shaft 1 under the dividing them partition 6 made of water cooled copper elements and submerged into slag bath. In the electric furnace 5 dispersed suspended material of metal (and matte) is settled with the formation of smelting products phases: lead bullion, zinc slag depleted by lead and polymetallic matte if it is formed. As usual, matte phase is formed when processing lead-bearing materials contain increased copper content. It allows rough decoppering of lead bullion with recovery of copper excess from processing lead-bearing materials into polymetallic matte directly in the unit. After settling zinc slag, lead bullion (and matte) are tapped from the electric furnace through facilities to tap smelting products 9 and transferred for further processing by means of the known methods for producing marketable products (on Figure 3 are not shown). Lead bullion is refined, zinc slag is undergone fuming or Waelz processing with recovery of zinc into oxidized zinc fumes, polymetallic matte is converted into crude copper. Produced mixture of reaction gases and roasting-smelting gases goes under the partition 3 into the gas exhaust shaft 4 adjacent to the reaction shaft 1. In the gas exhaust shaft 4 reaction gases are after-burnt up to complete oxidizing of carbon monoxide and zinc steams and cooled at the expense of heat exchange with surfaces of water cooled elements installed in the shaft. The mixture of reaction gases and dusts cooled up to 800-1000°C goes into a waste-heat boiler, where it is cooled up to 400-5 00°C and then - into the electrostatic precipitator (on Figure 3 they are not shown), where dusts are separated from sulfur dioxide reaction gases and returned for roasting-smelting together with charge. Sulfur dioxide gases are sent for sulphur utilization with production of marketable products of (sulphuric acid, elemental sulphur, sulphuric anhydride or salts). For better understanding of the present invention there are given examples illustrating the proposed method. Example 1 (by the prototype). On the semi-industrial plant, according to the known method, there was processed charge, prepared from sulphide lead concentrates, lead dusts, lead-bearing residues of zinc production, battery paste, quartz and lime fluxes, mass ratio of total amount of sulphide, elemental and pyrites sulphur to total content of sulphur in which was 0.6. As reductant of sulphates and iron higher oxides there was introduced into charge powdered brown coal with activation energy of carbon gasification reaction of 135.2 kJ/mol at the rate of 10 kg of pure carbon per 100 kg of ferric iron and 80 kg of pure carbon per 100 kg of sulphate sulphur. Prepared charge having the composition of, %: 28.27 of lead; 8.29 of zinc; 0.97 of copper; 13.02 of total iron (including ferric iron - 10.03); 8.01 of total sulphur (including sulphate sulphur - 3.09); 12.01 of silicon dioxide; 6.01 of calcium oxide and free moisture content of 10.7% was dried up to residual moisture content of 0.8% and fed through the burner for roasting-smelting in suspended state in technical-grade oxygen atmosphere (96%). To compensate low calorific capacity into charge as fuel there was added necessary amount of powdered coal, used at wet charge preparation and having the following composition: 43.76% of solid carbon, 38.46% of volatiles and 17.78% of ash, containing, %: 6.4 of iron, 52.1 of silicon dioxide, 5.2 of calcium oxide. Together with charge into the burner there were fed recycle dusts of roasting-smelting and crushed carbon reductant, mainly there was used coke breeze with the grain size of 5-20 mm, with the following composition, %: 86.64 of solid carbon, 4.31% of volatiles and 9.05% of ash, containing, %: 12.6 of iron, 57.1 of silicon dioxide, 10.3 of calcium oxide. In charge-oxygen flame of the burner lead-bearing materials and fluxes transferred into dispersed oxide melt and coke breeze having no time to burn dropped on the surface of slag bath forming on it warmed up layer of carbon reductant. Dispersed oxide melt of charge roasting-smelting in suspended state, penetrating through this layer, was reduced. Thereby, oxides of lead were reduced up to metal, iron higher oxides - up to wustite and zinc remained in oxide melt (slag). As a result there was produced lead bullion, zinc slag and dust-loaded gases of the reaction shaft, that were cooled and purified from dust, continuously returning to smelting together with charge. Smelting mode was controlled by the degree of charge desulphurization and the temperature of oxide melt in the flame lower point. For this purpose there was performed the choice of flame melt samples above the layer of carbon reductant and they were analyzed on sulphur content. Simultaneously, in this very point there was measured the temperature, that was controlled by means of the change of charge, powdered coal and oxygen consumption. Totally in the course of test 28 tons of dry charge were processed. Resulting average indices of the process effectiveness within the frameworks of the assigned task that were obtained, are presented in Table 1, test 1. Example 2. According to the applying method the test is realized as in Example 1, but it differs by the fact that charge dried up to residual moisture content of 0.8% is undergone granulation under different modes and classification, at which tree fractions are separated. Charge coarse fraction is sent to the second granulation, fine fraction - to wet charge preparation and average fraction - to roasting-smelting. Depending on conditions of granulation and classification there are changed upper and lower limits of the grain size range of particles mass portion of which amounts to 90% of dry charge, supplied to roasting-smelting stage. Smelting results are presented in Table 1, tests 2-6. Example 3. The method is realized as in Example 2, but it differs by the fact that to roasting-smelting there is supplied dry charge fraction with prevailing range of grain size of particles from 0.01 up to 0.1 mm and mass fraction of this fraction in charge is changed depending on conditions of its granulation and classification. Obtained results are presented in Table 1, tests 7-8. As it is seen from the Table (tests 1-8), main tasks of the patented method: the increase of lead recovery into lead bullion (column 7), the increase of specific capacity of the process (column 8) and reduction of specific consumption of energy carriers (columns 9-12) are simultaneously achieved at introduction of operations for granulation and dry charge classification, as a result of which isolated charge fraction is supplied for roasting-smelting, 90% of mass of which are particles with the grain sizes of 0.01-0.10 mm. At optimum fraction composition of dry charge it is seen (compare tests 1, 3-5 and 7): the increase of lead recovery into lead bullion by 2.5-2.7%, the increase of specific capacity by charge by 5.3-6.1%, the reduction of specific consumption of energy carriers on smelting by 13.4-14.8%. Example 4. The method is realized as in Example 2, under conditions of dry charge granulation and classification, when 90% of mass supplied to charge roasting-smelting is composed from particles with grain size composition of 0.01-0.10 mm (test 3), but differs by the fact that free moisture content in charge at the stage of its preparation is different (2, 8, 16 and 20%) and its drying is done up to one and the same residual moisture - 0.8%. As it is followed from obtained results, given in Table 2, tests 9-12, optimum indices of the process are achieved at free moisture content in charge of 8-16% at the stage of its preparation due to isolation of optimum fraction composition of dry charge. Additional effect, stipulated by the formation of more stable charge microstructure at recommended increase of minimum permissible content of free moisture in charge from 2-8% that amounts to (compare tests 9 and 10): the increase of lead recovery into lead bullion by 2.0 %, the increase of specific capacity by charge by 0.3 %, the reduction of specific consumption of energy carriers on smelting by 1.6%. Example 5. The method is realized as in Example 2, test 3, but it differs by the fact that as crushed carbon reductant instead of coke breeze with lumps grain size of 5-20 mm there was used coal of different quality with the same grain size. Obtained results are given in Table 3, tests 13-17. According to received data, the use of coals as crushed carbon reductant allows to increase the effectiveness of the process (compare with test 3) and maximum additional effect is observed in the recommended range of contents in dry coal mass from about 49 to about 80% of total carbon and from about 11 up to about 27% of volatiles. Maximum additional effect from coal use as crushed carbon reductant is observed in test 15 and amounts to: the increase of lead recovery into lead bullion by 2.3 %, the increase of specific capacity by charge by 0.3 %, the reduction of specific consumption of energy carriers on smelting by 5.5 %. The mass of dry charge processed in each of the tests 2-18 amounts to from 22 to 24 tons. Thus, given examples show that the patenting method allows to solve the assign task. Table 1 - Influence of dry charge fraction composition on indices of lead-bearing materials processing (Table 1 Removed) Table 2 - Influence of initial charge moisture on indices of lead-bearing materials processing (Table 2 Removed) Table 3 - Influence of the quality of carbon material on indices of lead-bearing materials processing (Table 3 Removed) We claim :- 1. The method to process lead-bearing materials comprising of charge preparation by means of thorough blending of wet sulphide and oxidized lead-bearing materials with fluxes and powdered carbon material at which mass ratio of total amount of sulphide, elemental and pyrites sulphur to total sulphur content in charge amounts to 0.08-0.87 and powdered carbon material having activation energy of carbon gasification reaction within the range of 56-209 kJ/mol is introduced as reductant on the basis of 4-12 kg of pure carbon per 100 kg of ferric iron and 20-140 kg of pure carbon per 100 kg of sulphate sulphur in charge; drying of produced wet charge up to residual moisture content less than 1%; roasting-smelting of dry charge in suspended state in oxygen atmosphere with production of dispersed oxide melt and the mixture of dusts and roasting-smelting gases; reduction of dispersed oxide melt at its filtration through the layer of warmed-up particles of crushed carbon reductant with the grain size of 2-50 mm with production of metallic lead, zinc-bearing oxide melt and gases mixing with dusts and gases of roasting-smelting of dry charge; separation of produced mixture of dusts and reaction gases with return of dusts to the stage of roasting-smelting of dry charge, characterized in that dry charge is undergone granulation and classification, and to the stage of roasting-smelting isolated fraction of dry charge is supplied, no less than 90% of its mass is composed from particles with the grain size of 0.01-0.10 mm. 2. The method to process lead-bearing materials as claimed in claim 1, wherein the content of free moisture in charge at the stage of its preparation amounts to 8-16%. 3. The method to process lead-bearing materials as claimed in claim 1, wherein the carbon reductant there is used coal with the content of total carbon in dry mass from about 49 to about 80% and volatiles from about 11 to about 27%.

Full Text

Method to process lead-bearing materials
Technical field
The invention is relative to non-ferrous metallurgy, mainly to methods to process lead-bearing materials of different origin.
There is an extensive group of lead-bearing materials such as hydrometallurgical processes residues, converting dusts of copper mattes, slurries of neutralization and process solutions purification that are not processed or processed in insufficient volume by well-known methods, so they are accumulated in dumps. In addition to lead, these materials contain considerable amount of zinc and copper that reduces recovery complexity of non-ferrous metals from natural mineral raw material in processes of its metallurgical processing. Simultaneously, the storage of lead-bearing materials causes complicated ecological problems. Thus, the range extension of processed lead-bearing materials represents an actual task for the technology and environment protection.
Prior art
There is known the method to process lead-bearing materials with increased sulphates content and oxides content like lead residues, dusts, battery paste, and others in the mixture of finely grained lead concentrates, recycle dusts, fluxes, coal dust - QSL-technology, based on the principle of bubbling smelting (Mager K., Shulte A. "Production and technological aspects of the first four QSL-plants". Proceedings of International Symposium on processing of primary and secondary lead. Halifax, Nova Scotia, Canada, August 20-24, 1989, Pergamon Press Publisher, New York, p. 15-26). The method lies in the fact that indicated mixture is granulated and resulted wet grains are fed on the surface of oxide melt, that contains from 35-60% of lead in the form of oxides. This oxide melt and the layer of metallic lead located under it are blown through by oxygen-containing gas. As a result of interaction between raw material sulphides with lead oxides at the temperature of 850-950°C lead bullion is formed that is partly transferred to oxide melt as a result of its oxidizing using oxygen-containing gas. By grains feed control and consumption of oxygen-containing gas there is achieved constant high concentration of lead oxides in slag and predominance of speed of lead bullion formation over the speed of its oxidizing using oxygen-containing gas. Resulting oxide melt with the temperature of no more than 950°C continuously goes to reduction area, where as the slag goes towards the outlet, melt temperature gradually increases up to 1150-1250°C at the expense of gas heating. Simultaneously with it lead oxides reduction up to lead bullion is realized by means of blowing of the melt by mixture of air and powdered or gaseous carbon material (coal, natural gas and others).
The disadvantage of the known method is low direct recovery of lead into lead bullion, low specific capacity of the process and simultaneously high specific consumption of energy

carriers (oxygen-containing gas, carbon materials). It is caused by the fact that the reduction of lead concentration in oxide melt leads to the necessity of increasing the temperature of this melt during oxidizing and reducing stages of the process, and, correspondingly, to the increase of lead output into smelting dusts (up to 50% and more from its mass in charge). During processing of lead-bearing materials with lead concentration less than 30% and iron oxidation rate more than 50-60%, the smelting process is almost destroyed due to viscous oxide melt formation, inapplicable for gas blowing.
There is also known the method to process lead-bearing materials with increased portion of sulphates and oxides like lead residues, dusts, battery paste, and others in the mixture of sulphide lead concentrates, recycle dusts, fluxes, coal dust - Ausmelt technology, based on bubbling smelting principle (Mounsey E.N., Piret N.L. "A review of Ausmelt technology for lead smelting". Proceedings of the Lead-Zinc 2000 Symposium. Pittsburgh, USA, October 22-25, 2000, p. 149-169). The method lies in the fact that mentioned well averaged mixture in finely grained or granulated form with lead concentration from 25-60% is fed on the surface of oxide melt. From above oxygen-containing gas is blown into oxide melt volume and at the deficit of the process heat balance there is also blown powdered, liquid and gaseous carbon fuel. As a result of interaction between raw material sulphides with lead oxides at the temperature of 1000-1100°C lead bullion is formed that is partly transferred to oxide melt as a result of its oxidizing using oxygen-containing gas. By charge feeding control and consumption of oxygen-containing gas there is achieved constant high concentration of lead oxides in slag and predominance of speed of lead bullion formation over the speed of its oxidizing using oxygen-containing gas. Resulting oxide melt with the temperature that is not higher than 1100°C is transferred to reduction process stage in continuous or intermittent mode or is tapped and granulated for further processing of solid lead slag at reduction stage with production of lead bullion. Lead oxides reduction to lead bullion from rich lead slag of oxidizing process stage is realized by means of melt blowing by the mixture of air and powdered, liquid or gaseous carbon material (coal, mazut, natural gas and others). Significant increase of energy carriers consumption with the accompanying increase of the temperature of oxide melt allows to transfer this process from the mode of lead bullion smelting into the mode of lead (and partly of zinc) fuming into smelting dusts, those can be then processed separately by this very method with the production of lead bullion.
Disadvantages of the well-known method are low lead recovery into lead bullion, low specific capacity of the process and simultaneously high consumption of energy carriers (oxygen-containing gas, carbon materials).
The closest technical substance is in the method to process lead-bearing materials, such
as lead and zinc residues, converting dusts, slurries of hydrolytic purification of process solutions that contain mainly simple or compound sulphates and metals oxides, including thermally stable sulphates (of lead, calcium) and higher iron oxides (Patent RK #9, C 22 B 13/02,1997).
According to this method the preparation of wet charge is realized from primary lead-bearing materials and fluxes with introduction in it as a reductant for powdered sulphide material up to mass ratio of total amounts of sulphide, elementary and pyrites sulphur to the total sulphur content in charge from 0.08 to 0.87 and/or powdered carbon material at the rate from 4 to 12 kg of pure carbon per 100 kg of ferric iron and from 20 to 140 kg of pure carbon per 100 kg of sulphate sulphur. Thereby, powdered carbon material is introduced with the activation energy of carbon gasification reaction in the range of 56-209 kJ/mol. As powdered carbon material there are used lead sulfide concentrates or lead (polymetallic) ore. Produced wet charge with recommended moisture content from 2 to 16% is dried up to the residual moisture content of less than 1%. Dried charge is transferred to roasting-smelting stage in suspended state in oxygen-containing gas atmosphere with the production of dispersed oxide melt and the mixture of dusts and roasting-smelting gases. Dispersed oxide melt produced at the stage of roasting-smelting, is reduced by means of its filtration through the layer of warmed-up particles of crushed carbon material (coke or coal) with the grain size of 2-50 mm with the production of lead bullion, zinc-bearing slag depleted by lead and gases mixing with roasting-smelting gases. Dusts are separated from the mixture of reaction gases and returned to the stage of roasting-smelting.
At the stage of wet charge preparation, under conditions of careful blending of materials containing natural binding compounds (soluble salts, metals hydroxides and hydrates, gypsum) and in the presence of free moisture in charge that is no less than 2% there is occurred its structuring with the formation of "complex" microconglomerates from inhomogeneous particles, including both oxidized components (sulphates and metals oxides) and reagent-reductants (metals sulphides and carbon). Bonds formed between inhomogeneous particles in microconglomerates at the stage of wet charge preparation are strengthened at the stage of charge drying. It provides thermal stability of microconglomerates particles under conditions of quick heating of dry powdered charge at the stage of roasting-smelting. The presence of close contact of sulphate and oxide components with sulphides and carbon in microconglomerates volumes provides significant speed-up of charge desulphurization process and decomposition of iron higher oxides at the stage of roasting-smelting of powdered charge in suspended state at temperatures of 1250-1350°C. The speed-up of the decomposition process of sulphates and iron higher oxides at temperatures that 300-500°C less than the
temperatures of their thermal decomposition is stipulated by the intensive flow of chemical
interaction of the following type in microconglomerates volumes of inhomogeneous particles:
Me'SO4 + Me2S -» Me'O(Me') +Me2O(Me2) + SO2; (1)
Me'O + Me2S -» Me'CKMe1) +Me2O(Me2) + SO2; (2)
Fe2O3 + MeS -* Fe3O4 + MeO + SO2; (3)
Fe3O4 + MeS -» FeO + MeO + SO2; (4)
MeSO4 + C -» MeO(Me, MeS) + CO2 + SO2; (5)
MeO + C ^ Me + CO; (6)
Fe2O3 + C -> Fe3O4 + CO; (7)
Fe3O4 + C -+ FeO + CO. (8)
Disadvantages of the known method are low recovery of lead into lead bullion, low
specific capacity of the process and at the same time high specific consumption of energy
carriers (oxygen-containing gas, carbon materials and electric power).
Stated disadvantages are determined by the fact that the known method does not provide sufficiently high content and optimal sizes of thermally stable "complex" microconglomerates in dry charge, supplied for roasting-smelting stage in suspended state. These both factors are stipulated by uncontrolled process of adhesion or disintegration of microconglomerates particles at the stage of wet charge drying.
At moisture of charge, that is supplied for drying stage, amounting to 2-7%, independently of the content of binding components in it, there is no enough free moisture to form bonds between particles, that are sufficient for mechanical and thermal stability of formed microconglomerates. It leads to disintegration of mechanically unstable microconglomerates and to decrepitation of thermally unstable microconglomerates at the stages of charge drying and roasting-smelting. As a result there is the decrease of "complex" microconglomerates particles content and the increase of mass portion of individual dispersed particles in charge at the stage of roasting-smelting. At higher moisture content of charge supplied for drying stage, the amount of free moisture is enough for formation of considerable number of stable bonds between particles. However, uncontrolled particles adhesion in the process of material drying leads to the formation of coarse-grain structure of dry charge with the possible formation of extremely large lumps of adhered particles, the roasting-smelting of which in suspended state is impossible without their additional granulation.
Both low content of thermally stable "complex" microconglomerates in dry charge, supplied for the stage of roasting-smelting and their extremely large sizes noticeably reduce the efficiency of processing of lead-bearing materials with increased portion of sulphates, iron higher oxides and zinc oxides by means of the known method. Low portion of "complex"
microconglomerates in dry charge reduces the contact degree between inhomogeneous particles-reagents, and large sizes of microconglomerates decrease the rate of their heating at the stage of charge roasting-smelting. Both factors lead to the intensity reduction of low temperature interactions between charge components according to reactions (l)-(8) and stipulate the necessity to increase the temperature of roasting-smelting up to 1400-1450°C for more complete decomposition of thermally stable sulphates and the increase of fluidity of oxide melts with increased content of iron higher oxides.
Increased temperatures of roasting-smelting lead to relatively high specific consumptions of powdered carbon fuel and oxygen for its oxidizing and to considerable increase of recycle dusts output, thereby preventing the reduction of iron higher oxides content in dispersed oxide melt.
Viscosity of oxide melts, saturated with iron higher oxides, is increased while there is reduction of lead oxide in the layer of crushed carbon material. As a result, there is the rise of slowdown effect of the filtration process and of oxide melt reduction, worsened by considerable heat absorption for iron higher oxides reduction. Maintenance of high fluidity and the increase of oxide melt reduction degree under these conditions requires heat input or reduction of oxide melt supply to the process of reduction stage.
Thus, the known method does not provide effective realization of low temperature interactions of charge components at the stage of roasting-smelting and further effective reduction of oxide melts in the layer of crushed carbon reductant.
Thereby, one of the most significant factors of reducing efficiency of the known method is underestimated lower limit of recommended range of free moisture content in wet charge, supplied for drying procedure.
Additional factors of reduced efficiency of the known method might be the use of recommended carbon materials for the formation of the layer of crushed carbon reductant.
The use of coke having the lowest reaction capacity in a number of carbon materials stipulates relatively low rate of reduction of oxide melt during its filtration through the layer of crushed reductant, limiting by this the specific capacity of the process. To increase the rate of reduction there is required the increase of oxide melt temperature. However, the increase of its temperature at the stage of charge roasting-smelting leads not only to the increase of specific consumption of energy carriers (powdered fuel and oxygen for its burning), but also to the decrease of lead recovery into lead bullion at the expense of increase of degree of lead transfer into roasting-smelting dusts. Thereby, the increase of recycle dusts portion in charge might reduce the specific capacity of the process in higher degree than the increase of oxide melt temperature at the stage of roasting-smelting allows its increasing.
Reaction capacity of coal is higher than that of coke. However, in contrast with coke, not all coals possess thermal stability under conditions of quick heating and when they get onto the surface of slag bath they might decrepitate. Thereby, the layer permeability of crushed carbon reductant for dispersed oxide melt is significantly reduced or completely destroyed. Correspondingly, there is decreased the surface and the rate of reduction reactions flow. It leads to corresponding decrease of lead recovery into lead bullion and of specific capacity of the process (up to its complete failure). Moreover, the need to increase fluidity and, correspondingly, the temperature of oxide melt at the decrease in the layer permeability of crushed reductant stipulates the increase of energy carries specific consumption that is unavoidable in this case.
As the basis for this invention there was put the task to change the known method of processing of lead-bearing materials with increased concentration of thermally stable sulphates and iron higher oxides thus in order to increase lead recovery into lead bullion and specific capacity of the process at simultaneous reduction of energy carriers specific consumption.
Abstract of the disclosure
The assigned task is achieved by the fact that in the method to process lead-bearing materials that includes charge preparation by means of thorough blending of wet sulphide and oxidized lead-bearing materials with fluxes and powdered carbon material at which mass ratio of total amount of sulphide, elemental and pyrites sulphur to total sulphur content in charge amounts to 0.08-0.87 and powdered carbon material having activation energy of carbon gasification reaction within the range of 56-209 kJ/mol is introduced as reductant on the basis of 4-12 kg of pure carbon per 100 kg of ferric iron and 20-140 kg of pure carbon per 100 kg of sulphate sulphur in charge; drying of produced wet charge up to residual moisture content less than 1%; roasting-smelting of dry charge in suspended state in oxygen atmosphere with the production of dispersed oxide melt and the mixture of dusts and roasting-smelting gases; reduction of dispersed oxide melt at its filtration through the layer of warmed-up particles of crushed carbon reductant with the grain size of 2-50 mm with the production of metallic lead, zinc-bearing oxide melt and gases, mixing with dusts and gases of roasting-smelting; separation of produced mixture of dusts and reaction gases with return of dusts to the stage of roasting-smelting, dry charge is undergone granulation and classification, and to the stage of roasting-smelting isolated fraction of dry charge is supplied, no less than 90% of its mass is composed from particles with the grain size of 0.01-0.10 mm.
It is advisable that the content of free moisture in charge at the stage of its preparation was 8-16%.
It is reasonable that as carbon reductant to the stage of dispersed oxide melt reduction there was supplied coal with the content of total carbon in dry mass from about 49 up to about 80% and of volatiles from about 11 up to about 27%.
The method to process lead-bearing materials includes charge preparation by means of thorough blending of wet sulphide and oxidized lead-bearing materials with fluxes and powdered carbon material at which mass ratio of total amount of sulphide, elemental and pyrites sulphur to total sulphur content in charge amounts to 0.08-0.87 and powdered carbon material having activation energy of carbon gasification reaction within the range of 56-209 kJ/mol is introduced as reductant on the basis of 4-12 kg of pure carbon per 100 kg of ferric iron and 20-140 kg of pure carbon per 100 kg of sulphate sulphur in charge; drying of produced wet charge up to residual moisture content less than 1%; roasting-smelting of dry charge in suspended state in oxygen atmosphere with production of dispersed oxide melt and the mixture of dusts and roasting-smelting gases; reduction of dispersed oxide melt at its filtration through the layer of warmed-up particles of crushed carbon reductant with the grain size of 2-50 mm with production of metallic lead, zinc-bearing oxide melt and gases mixing with dusts and gases of roasting-smelting of dry charge; separation of produced mixture of dusts and reaction gases with return of dusts to the stage of roasting-smelting of dry charge, differing by the fact that dry charge is undergone granulation and classification, and to the stage of roasting-smelting isolated fraction of dry charge is supplied, no less than 90% of its mass is composed from particles with the grain size of 0.01-0.10 mm.
The achievement of the assigned task at realization of proposed solutions is provided by the following factors:
- formation of charge microstructure with high portion of mechanically and thermally
stable microconglomerates of inhomogeneous particles, including sulphate, oxide, sulphide
and carbon components;
- stabilization of optimum fraction composition and microstructure of dry charge,
supplied to the stage of roasting-smelting in suspended state;
- intensification of low temperature interactions of sulphate and oxide components with
sulphides and carbon at the stage of charge roasting-smelting in suspended state;
- oxide melt reduction intensification at the stable maintenance of porous structure and
permeability of crushed carbon reductant layer.
By morphological researches of charge there was found out that minimum size of "complex" microconglomerates of inhomogeneous particles amounts to about 0.01 mm. More dispersed charge fractions comprise separate, non-associated particles or microconglomerates from single-type highly dispersed particles of lead-bearing materials, possessing increased
adhesive properties (such as dust, residues, slurries).
From analyses of results of experimental smelting it is known that the increase of portion of fine fractions with particles grain size less than 0.01 mm as well as the increase of coarse fraction portion with individual and associated particles having grain size of more than 0.1 mm in dry charge lead to reduction of rate and degree of its components transformation at the stage of roasting-smelting in suspended state and prevent the achievement of the assigned task.
Negative effect on indices of the process of increased portion of fine and coarse fraction in dry charge material is successfully eliminated by means of introduction of successive operations of granulation and classification of dry charge before its supply to the stage of roasting-smelting.
The combination of granulation and classification operations provides the production of isolated fraction of dry charge, no less than 90% of particles mass of which is in the range of 0.01-0.10 mm, that allows:
- to keep in dry charge after its grinding microconglomerates of inhomogeneous
particles, including sulphate, oxide, sulphide and carbon components;
- to limit the entry of excessively fine (less than 0.01 mm) and excessively coarse
(more than 0.10 mm) individual particles and microconglomerates going to the stage of
roasting-smelting, that prevent the increase of charge desulphurization degree and
decomposition of iron higher oxides at the stage of charge roasting-smelting at reduced
temperature modes of the process.
Thereby, the stabilization of fraction composition of dry charge within the range of prevailing particles grain size of 0.01-0.10 mm allows effective solution of the assigned task.
Increased direct recovery of lead into lead bullion, the increase of specific capacity of the process and simultaneous reduction of specific energy consumption are achieved thereby at the expense of:
- prevention of poor matte formation;
- decrease of dust entrainment and the portion of smelting recycle dusts in charge;
- increase of the degree of lead reduction from fluid oxide melt in the layer of crushed
carbon material;
- decrease of consumption of powdered carbon fuel and of oxygen for its burning and
electric power for compensation of heat losses in reduction reactions of iron higher oxides in
the layer of carbon reductant.
The decrease of lower limit of dry charge particles grain size less than 0.01 mm reduces the degree of low temperature interactions flow of its components at the stage of
roasting-smelting in reactions (l)-(8) because of decrease of "complex" microconglomerates portion in charge. It stipulates the necessity to increase the temperature of the process. Moreover, there is the increase of mechanical carry over of fine particles into roasting-smelting dusts. In the aggregate it leads to the decrease in lead recovery into lead bullion, the decrease of specific capacity of the process and increase of specific consumption of energy carriers.
The increase of upper limit of dry charge particles grain size less than 0.01 mm reduces the degree of low temperature interactions flow of its components at the stage of roasting-smelting at the expense of the rate reduction of coarse particles heating and the decrease of total reaction surface of components, that also stipulates the necessity to increase the temperature of the process and prevents from the achievement of the assigned task.
The decrease of mass portion of particles with the grain size from 0.01 up to 0.10 mm in dry charge that is less than 90%, as in the case of change of limits of optimal rage of particles grain size, results in the degree reduction of low temperature interactions flow of its components at the stage of roasting-smelting. It can happen either at the expense of the decrease of "complex" microconglomerates portion or at the expense of the increase of extremely coarse individual particles and microconglomerates in charge. Both factors stipulate the necessity to increase the process temperature. As a result, there is the decrease of lead recovery into lead bullion and of specific capacity of the process and specific consumption of energy carriers is increased.
According to the patented method, thorough blending of materials at the stage of wet charge preparation is required to conduct at free moisture content in charge mixture amounting to 8-16%. On the basis of experimental data it allows:
1) to form charge homogeneous microstructure with large portion of "complex"
microconglomerates of inhomogeneous particles, including sulphate, oxide, sulphide and
carbon components;
2) to form sufficient number of stable bonds between inhomogeneous particles,
providing thermal stability of "complex" microconglomerates at the stage of dry charge
roasting-smelting.
The mentioned range of free moisture content is optimal, because it provides the most significant increase of "complex" microconglomerates portion in charge at the stage of its preparation and strengthening of these microconglomerates at the stage of wet charge drying.
At free moisture content of less than 8% there is decrease of "complex" microconglomerates portion in wet charge, supplied for charge drying, as well as the decrease of mechanical and thermal stability of such microconglomerates in dry charge. It reduces the
degree of charge components interactions flow at the stage of roasting-smelting and leads to deterioration of process indices within the framework of the assigned task.
At free moisture content of 8% and more "complex" microconglomerates portion in wet charge, supplied for charge drying is noticeablely increased. There is also the increase of mechanical and thermal stability of such microconglomerates in dry charge. In spite of the fact that in this case as well as in prototype there is uncontrolled adhesion of particles at the stage of drying, the use of successive operations of granulation and classification of dry charge in the patented method excludes entering of its extremely coarse fractions to the stage of roasting-smelting. Thereby, there is provided the possibility of maximum effective process conducting.
The increase of free moisture content in charge more than 16% is unpractical because does not lead to noticeable increase of "complex" microconglomerates portion in dry charge at the stage of roasting-smelting and, correspondingly - to increase of the process indices within the framework of the assigned task. At the same time, evaporation of moisture excess requires the increase of fuel consumption for charge drying, i. e. increases total specific consumption of energy carriers.
As crushed carbon reductant of dispersed oxide melt from the stage of charge roasting-smelting in the prototype there is suggested coke or coal. Due to the presence of active hydrocarbons (volatiles) and much less activation energy of solid carbon gasification reaction, coal usually possesses higher reduction capacity in comparison with coke. However, in contrast with coke, not all kinds of coal possess thermal stability and under conditions of quick heating they might decrepitate on the surface of slag bath, that is not taken into consideration in the prototype. At the same time, decrepitation of coal might not only reduce the degree of oxide melt reduction in the layer of carbon reductant dramatically but completely disturb the flow of reduction process. Thermal stability of coal is directly connected with its caking capacity during calcination. The more caking capacity of coal the higher its thermal stability is. On the basis of this interrelation and the analysis of experimental data, there was determined optimal range of coals quality, possessing thermal capacity that is higher enough. According to the patented method, as crushed carbon reductant there is reasonable to use coal with the content of total carbon in dry mass from about 49% up to about 80% and volatiles - from about 11% up to about 27%.
The use of coal with the stated range of total carbon and volatiles content as crushed carbon reductant enhances the effectiveness of the process reduction stage at the expense of the increase of reductant activity at keeping of developed reaction surface and high permeability of crushed reductant layer for dispersed oxide melt. It allows additional increase
of lead recovery into lead bullion and of specific capacity of the process without oxide melt temperature rise, providing by that additional economy of specific consumption of energy carriers.
On the one hand, total carbon in coal dry mass comprises of solid carbon and volatiles carbon and on the other hand, solid carbon and volatiles comprise the basis of coal dry mass. Thereby, recommended ranges of total carbon and volatiles content in coal dry mass are closely connected and therefore, it is reasonable to consider them together.
At reduction of total carbon content in coal dry mass less than 52% and at accompanying increase of volatiles content in that mass more than about 27%, coal caking capacity at calcination and its thermal stability under conditions of quick heating are noticeably decreased. The increase of decrepitation degree of crushed carbon lumps on the surface of slag bath reduces permeability of carbon reductant layer. As a result, interdependently there is reduced oxide melt reduction rate, the degree of lead recovery into lead bullion and specific capacity of the process. Moreover, the decrease of the process reduction stage intensity leads to the increase of energy carriers specific consumption stipulated by the necessity to increase fluidity and, correspondingly, oxide melt temperature as well as compensation of increasing heat losses for its reduction and settling.
At increased content of solid carbon in coal dry mass more than about 80% and accompanying reduction of volatiles content in this mass less than about 10%, coal caking capacity at its calcination and its thermal stability under conditions of quick heating are also noticeablely decreased. It is determined by optimal nature of coals calcination stipulated by the presence in their content of bituminous substances - products of transformation of waxes, resins and fatty substances contained in plants-coal creators. Portion of such substances is reduced in coals with low degree of metamorphism - lignites as well as in coals with high degree of metamorphism - antracites. Dependence of coals caking capacity on their content in dry mass of total carbon and volatiles, represented in standard units, given on Figures 1 and 2. From presented data it is seen that coals recommended in patented method, containing total carbon in dry mass from about 49% up to about 80% and of volatiles from about 11% up to about 27% possess the highest degree of caking capacity. The reduction of caking capacity and coal thermal stability, as described above, leads to deterioration of the process indices within frameworks of the assigned task.
The method is realized in the unit, the principal scheme of which is represented on Figure 3. The unit consists of the vertical reaction shaft 1 of rectangular cross-section in the roof of which there is installed the burner 2 to supply charge, oxygen, recycle dusts and crushed carbon reductant; the vertical partition wall 3 water cooled copper elements separating the reaction shaft 1
from the gas exhaust shaft 4 with keeping of gas clearance above slag bath to withdraw reaction gases; the electric furnace 5 adjacent to the smelting chamber and separated from it by the vertical partition 6 submerged into slag bath and having water cooled copper elements; the hearth 7 common for the reaction shaft 1, the electric furnace 5 and the gas exhaust shaft 4; the jacketed belt 8 and facilities to tap smelting products 9.
The method is realized by the following way.
Using chemical analysis data for lead-bearing materials, that might be lead concentrates, dusts, residues and slurries of hydrometallurgical production, battery pastes, refining recycles of lead bullion and other materials, proportions are calculated and materials are blended in such ratio at which mass ratio of total amount of sulphide, elemental and pyrites sulphur to the total content of sulphur in charge amounts to 0.08-0.87. To the produced mixture of wet lead-bearing materials there are added fluxes (limestone, quartz sand and suchlike) and powdered carbon reductant. As powdered carbon reductant there might be used different coal types (lignites, coal and charcoal), coal concentrates, produced from clinker after Waelz processing, wastes of coke production and others. To achieve optimal combination of areas of heat release and absorption in reactions of charge components transformation at the stage of roasting-smelting it is reasonable to introduce in it powdered carbon materials with activation energy of carbon gasification reaction within the range of 56-209 kJ/mol. The addition of powdered carbon material is realized at the rate from 4 to 12 kg of pure carbon per 100 kg of ferric iron and from 20 to 140 kg of pure carbon per 100 kg of sulphate sulphur in charge.
Produced charge with free moisture content in it of 8-16% is undergone homogenization by means of thorough blending of materials. It allows forming homogeneous microstructure of charge with large portion of "complex" microconglomerates of inhomogeneous particles, including sulphate, oxide, sulphide and carbon components. At free moisture content in charge less than 8% it is required firstly to wet charge up to this minimal level and then to conduct its homogenization. At free moisture content in charge more than 16% it is required firstly to conduct its homogenization and then to remove the excess of free moisture (for example, by means of filtration of material) in order to avoid excessive consumption of fuel necessary for charge drying.
Wet homogenized charge is supplied for drying, where it is dried up to moisture residual content of less than 1%.
Produces dry charge, containing coarse fractions of adhered particles, is undergone granulation, and granulated powdered material - classification. Coarse fraction of dry powdered charge with prevailing particles grain size more than 0.10 mm is returned for granulation, dispersed fraction with prevailing particles grain size less than 0.01 mm is returned to the stage of
wet charge preparation and fraction, no less than 90% of mass of which is composed from particles with the grain size of 0.01-0.10 mm - to the stage of roasting-smelting. It provides conservation of dry powdered charge, supplied to the stage of roasting-smelting, considerable portion of thermally stable "complex" microconglomerates, formed at stages of preparation and wet charge drying.
At insufficient calorific capacity of dry charge the necessary amount of powdered carbon fuel is introduced into it. As such fuel there might be used the same powdered carbon material that is introduced into wet charge as reductant for iron higher oxides and sulphates at the stage of its preparation or other powdered carbon material having high calorific power.
Before supplying to the stage of roasting-smelting in charge there are introduced the process recycle dusts and crushed carbon reductant with the grain size of 2-50 mm, the most preferable grain size is 5-20 mm. As crushed carbon reductant there might be used different carbon materials - coal coke or petroleum coke, clinker after Waelz processing, charcoal and others. However, according to the patented method it is more preferable to use as crushed carbon reductant coal in dry mass of which there are contained from about 49 up to about 80% of total carbon and from about 11 up to about 27% of volatiles. Coals of such quality possess sufficiently high caking capacity and thermal stability, allowing to form stable porous structure of crushed carbon reductant with developed reaction surface and high permeability for reduction of oxide melt. Due to the presence of active hydrocarbonic component and reduced activation energy of carbon gasification reaction, such coals are more active carbon reductant than carbon materials, that passed thermal processing (cokes).
Dry powdered charge together with powdered carbon fuel (if necessary), recycle dusts and crushed carbon reductant is supplied through the vertical burner 2 into the reaction shaft 1 for roasting-smelting in suspended state in the atmosphere of oxygen-containing gas.
Oxygen consumption is determined at the rate of full degree of desulphurization and oxidation of sulphides of lead, zinc and iron up to oxides and carbon fuel up to carbon dioxide and water steams with the deduction of metals sulphates consumption and iron higher oxides for reactions of interaction with sulphide, elemental and pyrites sulphur and carbon of powdered carbon reductant according to stoichiometry of total reactions:
3Me1SO4 + Me2S -» SMe'O +Me2O + 4SO2; (9)
3Fe2O3 + MeS -> 6FeO + MeO + SO2; (10)
2MeSO4 + C -» 2MeO + CO2 + 2SO2; (11)
2Fe2O3 + C -* 4FeO + CO2. (12)
In other words, oxygen consumption is reduced by the value determined by the amount of oxygen, "connected" in sulphates and iron higher iron oxides. Moreover, for oxidizing of pure carbon of carbon reductant oxygen is not introduced.
Under the influence of high temperatures in reaction shaft powdered charge is ignited, warmed up very quickly up to the temperatures of 1250-13 50°C at the expense of oxidizing by oxygen of gas phase of part of sulphides and powdered carbon material. Thereby, in volumes of "complex" microconglomerates of particles in temperature areas of 350-700°C intensive interactions of sulphates and metal oxides (including iron higher oxides) with sulphides and carbon flow. As a result there is formed dispersed oxide melt with reduced content of iron higher oxides that possesses high fluidity and the mixture of dusts and sulfur dioxide reaction gases.
Crushed carbon reductant, supplied together with charge, due to large grain sizes of lumps (mainly 5-20 mm) as well as due to quick reduction of oxygen concentration in gas phase by the height of the reaction shaft 1 (above the heel of slag bath the concentration of oxygen amounts to about 1-2%) has no time to burn in the reaction shaft 1 and forms porous, continuously refilling reductive layer from greatly warmed up lumps of carbon material on the surface of slag bath under the burner 2. Dispersed oxide melt produced during charge roasting-smelting is filtered through this layer of crushed carbon reductant. Thereby, lead oxides are reduced up to metal, iron higher oxides - up to wustite and zinc oxides have no time to reduce in noticeable degree and together with wustite and fluxing components form zinc slag depleted by lead. Copper oxides as well as lead oxides are reduced in the layer of carbon reductant up to metal and transfer into lead bullion and non-ferrous metals sulphides, presenting in dispersed melt of roasting-smelting, are distributed between metallic and slag phases (at charge desulphurization degree more than 90-94%) or form dispersed matte phase. Gaseous products of reduction reactions (CO, CC>2 and zinc steams) go out from the layer of carbon reductant and mix with gases and roasting-smelting dusts.
Zinc slag depleted by lead containing dispersed suspended material of metallic lead (and matte, if such is formed) flows into the electric furnace 5 adjacent with the reaction shaft 1 under the dividing them partition 6 made of water cooled copper elements and submerged into slag bath. In the electric furnace 5 dispersed suspended material of metal (and matte) is settled with the formation of smelting products phases: lead bullion, zinc slag depleted by lead and polymetallic matte if it is formed. As usual, matte phase is formed when processing lead-bearing materials contain increased copper content. It allows rough decoppering of lead bullion with recovery of copper excess from processing lead-bearing materials into polymetallic matte directly in the unit. After settling zinc slag, lead bullion (and matte) are tapped from the electric furnace through facilities to tap smelting products 9 and transferred for further processing by means of the known methods for producing marketable products (on Figure 3 are not shown). Lead bullion is refined, zinc slag is undergone fuming or Waelz
processing with recovery of zinc into oxidized zinc fumes, polymetallic matte is converted into crude copper.
Produced mixture of reaction gases and roasting-smelting gases goes under the partition 3 into the gas exhaust shaft 4 adjacent to the reaction shaft 1. In the gas exhaust shaft 4 reaction gases are after-burnt up to complete oxidizing of carbon monoxide and zinc steams and cooled at the expense of heat exchange with surfaces of water cooled elements installed in the shaft. The mixture of reaction gases and dusts cooled up to 800-1000°C goes into a waste-heat boiler, where it is cooled up to 400-5 00°C and then - into the electrostatic precipitator (on Figure 3 they are not shown), where dusts are separated from sulfur dioxide reaction gases and returned for roasting-smelting together with charge. Sulfur dioxide gases are sent for sulphur utilization with production of marketable products of (sulphuric acid, elemental sulphur, sulphuric anhydride or salts).
For better understanding of the present invention there are given examples illustrating the proposed method.
Example 1 (by the prototype). On the semi-industrial plant, according to the known method, there was processed charge, prepared from sulphide lead concentrates, lead dusts, lead-bearing residues of zinc production, battery paste, quartz and lime fluxes, mass ratio of total amount of sulphide, elemental and pyrites sulphur to total content of sulphur in which was 0.6. As reductant of sulphates and iron higher oxides there was introduced into charge powdered brown coal with activation energy of carbon gasification reaction of 135.2 kJ/mol at the rate of 10 kg of pure carbon per 100 kg of ferric iron and 80 kg of pure carbon per 100 kg of sulphate sulphur. Prepared charge having the composition of, %: 28.27 of lead; 8.29 of zinc; 0.97 of copper; 13.02 of total iron (including ferric iron - 10.03); 8.01 of total sulphur (including sulphate sulphur - 3.09); 12.01 of silicon dioxide; 6.01 of calcium oxide and free moisture content of 10.7% was dried up to residual moisture content of 0.8% and fed through the burner for roasting-smelting in suspended state in technical-grade oxygen atmosphere (96%). To compensate low calorific capacity into charge as fuel there was added necessary amount of powdered coal, used at wet charge preparation and having the following composition: 43.76% of solid carbon, 38.46% of volatiles and 17.78% of ash, containing, %: 6.4 of iron, 52.1 of silicon dioxide, 5.2 of calcium oxide. Together with charge into the burner there were fed recycle dusts of roasting-smelting and crushed carbon reductant, mainly there was used coke breeze with the grain size of 5-20 mm, with the following composition, %: 86.64 of solid carbon, 4.31% of volatiles and 9.05% of ash, containing, %: 12.6 of iron, 57.1 of silicon dioxide, 10.3 of calcium oxide.
In charge-oxygen flame of the burner lead-bearing materials and fluxes transferred into
dispersed oxide melt and coke breeze having no time to burn dropped on the surface of slag bath forming on it warmed up layer of carbon reductant. Dispersed oxide melt of charge roasting-smelting in suspended state, penetrating through this layer, was reduced. Thereby, oxides of lead were reduced up to metal, iron higher oxides - up to wustite and zinc remained in oxide melt (slag). As a result there was produced lead bullion, zinc slag and dust-loaded gases of the reaction shaft, that were cooled and purified from dust, continuously returning to smelting together with charge.
Smelting mode was controlled by the degree of charge desulphurization and the temperature of oxide melt in the flame lower point. For this purpose there was performed the choice of flame melt samples above the layer of carbon reductant and they were analyzed on sulphur content. Simultaneously, in this very point there was measured the temperature, that was controlled by means of the change of charge, powdered coal and oxygen consumption.
Totally in the course of test 28 tons of dry charge were processed. Resulting average indices of the process effectiveness within the frameworks of the assigned task that were obtained, are presented in Table 1, test 1.
Example 2. According to the applying method the test is realized as in Example 1, but it differs by the fact that charge dried up to residual moisture content of 0.8% is undergone granulation under different modes and classification, at which tree fractions are separated. Charge coarse fraction is sent to the second granulation, fine fraction - to wet charge preparation and average fraction - to roasting-smelting. Depending on conditions of granulation and classification there are changed upper and lower limits of the grain size range of particles mass portion of which amounts to 90% of dry charge, supplied to roasting-smelting stage. Smelting results are presented in Table 1, tests 2-6.
Example 3. The method is realized as in Example 2, but it differs by the fact that to roasting-smelting there is supplied dry charge fraction with prevailing range of grain size of particles from 0.01 up to 0.1 mm and mass fraction of this fraction in charge is changed depending on conditions of its granulation and classification. Obtained results are presented in Table 1, tests 7-8.
As it is seen from the Table (tests 1-8), main tasks of the patented method: the increase of lead recovery into lead bullion (column 7), the increase of specific capacity of the process (column 8) and reduction of specific consumption of energy carriers (columns 9-12) are simultaneously achieved at introduction of operations for granulation and dry charge classification, as a result of which isolated charge fraction is supplied for roasting-smelting, 90% of mass of which are particles with the grain sizes of 0.01-0.10 mm. At optimum fraction composition of dry charge it is seen (compare tests 1, 3-5 and 7): the increase of lead recovery
into lead bullion by 2.5-2.7%, the increase of specific capacity by charge by 5.3-6.1%, the reduction of specific consumption of energy carriers on smelting by 13.4-14.8%.
Example 4. The method is realized as in Example 2, under conditions of dry charge granulation and classification, when 90% of mass supplied to charge roasting-smelting is composed from particles with grain size composition of 0.01-0.10 mm (test 3), but differs by the fact that free moisture content in charge at the stage of its preparation is different (2, 8, 16 and 20%) and its drying is done up to one and the same residual moisture - 0.8%. As it is followed from obtained results, given in Table 2, tests 9-12, optimum indices of the process are achieved at free moisture content in charge of 8-16% at the stage of its preparation due to isolation of optimum fraction composition of dry charge. Additional effect, stipulated by the formation of more stable charge microstructure at recommended increase of minimum permissible content of free moisture in charge from 2-8% that amounts to (compare tests 9 and 10): the increase of lead recovery into lead bullion by 2.0 %, the increase of specific capacity by charge by 0.3 %, the reduction of specific consumption of energy carriers on smelting by 1.6%.
Example 5. The method is realized as in Example 2, test 3, but it differs by the fact that as crushed carbon reductant instead of coke breeze with lumps grain size of 5-20 mm there was used coal of different quality with the same grain size. Obtained results are given in Table 3, tests 13-17. According to received data, the use of coals as crushed carbon reductant allows to increase the effectiveness of the process (compare with test 3) and maximum additional effect is observed in the recommended range of contents in dry coal mass from about 49 to about 80% of total carbon and from about 11 up to about 27% of volatiles. Maximum additional effect from coal use as crushed carbon reductant is observed in test 15 and amounts to: the increase of lead recovery into lead bullion by 2.3 %, the increase of specific capacity by charge by 0.3 %, the reduction of specific consumption of energy carriers on smelting by 5.5 %. The mass of dry charge processed in each of the tests 2-18 amounts to from 22 to 24 tons.
Thus, given examples show that the patenting method allows to solve the assign task.
Table 1 - Influence of dry charge fraction composition on indices of lead-bearing materials processing
(Table 1 Removed)
Table 2 - Influence of initial charge moisture on indices of lead-bearing materials processing
(Table 2 Removed)
Table 3 - Influence of the quality of carbon material on indices of lead-bearing materials processing
(Table 3 Removed)

We claim :-
1. The method to process lead-bearing materials comprising of charge preparation by means of thorough blending of wet sulphide and oxidized lead-bearing materials with fluxes and powdered carbon material at which mass ratio of total amount of sulphide, elemental and pyrites sulphur to total sulphur content in charge amounts to 0.08-0.87 and powdered carbon material having activation energy of carbon gasification reaction within the range of 56-209 kJ/mol is introduced as reductant on the basis of 4-12 kg of pure carbon per 100 kg of ferric iron and 20-140 kg of pure carbon per 100 kg of sulphate sulphur in charge; drying of produced wet charge up to residual moisture content less than 1%; roasting-smelting of dry charge in suspended state in oxygen atmosphere with production of dispersed oxide melt and the mixture of dusts and roasting-smelting gases; reduction of dispersed oxide melt at its filtration through the layer of warmed-up particles of crushed carbon reductant with the grain size of 2-50 mm with production of metallic lead, zinc-bearing oxide melt and gases mixing with dusts and gases of roasting-smelting of dry charge; separation of produced mixture of dusts and reaction gases with return of dusts to the stage of roasting-smelting of dry charge, characterized in that dry charge is undergone granulation and classification, and to the stage of roasting-smelting isolated fraction of dry charge is supplied, no less than 90% of its mass is composed from particles with the grain size of 0.01-0.10 mm.
2. The method to process lead-bearing materials as claimed in claim 1, wherein the content of free moisture in charge at the stage of its preparation amounts to 8-16%.
3. The method to process lead-bearing materials as claimed in claim 1, wherein the carbon reductant there is used coal with the content of total carbon in dry mass from about 49 to about 80% and volatiles from about 11 to about 27%.

Documents:

6450-delnp-2007-abstract.pdf

6450-DELNP-2007-Claims-(17-01-2012).pdf

6450-DELNP-2007-Claims-(29-06-2011).pdf

6450-delnp-2007-claims.pdf

6450-DELNP-2007-Correspodence Others-(29-06-2011)-.pdf

6450-delnp-2007-Correspondence Others-(05-06-2012).pdf

6450-delnp-2007-Correspondence Others-(13-07-2011).pdf

6450-DELNP-2007-Correspondence Others-(17-01-2012).pdf

6450-DELNP-2007-Correspondence Others-(29-06-2011)...pdf

6450-DELNP-2007-Correspondence Others-(29-06-2011)..pdf

6450-DELNP-2007-Correspondence Others-(29-06-2011).pdf

6450-delnp-2007-correspondence-others 1.pdf

6450-delnp-2007-correspondence-others.pdf

6450-delnp-2007-description (complete).pdf

6450-delnp-2007-drawings.pdf

6450-DELNP-2007-Form-1-(29-06-2011).pdf

6450-delnp-2007-form-1.pdf

6450-DELNP-2007-Form-13-(29-06-2011).pdf

6450-delnp-2007-form-18.pdf

6450-DELNP-2007-Form-2-(29-06-2011).pdf

6450-delnp-2007-form-2.pdf

6450-delnp-2007-form-26.pdf

6450-delnp-2007-Form-3-(13-07-2011).pdf

6450-DELNP-2007-Form-3-(29-06-2011).pdf

6450-delnp-2007-form-3.pdf

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Patent Number

250760

Indian Patent Application Number

6450/DELNP/2007

PG Journal Number

04/2012

Publication Date

27-Jan-2012

Grant Date

24-Jan-2012

Date of Filing

20-Aug-2007

Name of Patentee

STATE AFFILIATE "THE EASTERN MINING AND METALLURGICAL RESEARCH INSTITUTE FOR NON-FERROUS METALS" OF REPUBLIC STATE AFFILIATE "NATIONAL ENTERPRISE OF COMPLEX PROCESSING FOR MINERAL AND RAW MATERIAL OF THE REPUBLIC OF KAZAKHSTAN" (SA "VNIITSVETMET" RSA "NE CPMRM RK")

Applicant Address

1,PROMYSHLENNAYA ST., UST-KAMENOGORSK, 070002 KAZAKHSTAN REPUBLIC

Inventors:

#	Inventor's Name	Inventor's Address
1	CHALENKO VALENTINA VASILYEVNA	UTEPOV ST.7, APT. 25, UST-KAMENOGORSK, 070016, KAZAKHSTAN
2	SHUMSKIY VIKTOR ALEXANDROVICH	SOLNECHNAYA ST. 6/1,APT.24,UST-KAMENOGORSK, 070015, KAZAKHSTAN
3	USHAKOV NIKOLAY NIKOLAYEVICH	VOROSHILOV ST.167, APT.7,UST-KAMENOGORSK, 070018,KAZAKHSTAN
4	STARTSEV IGOR VLADIMIROVICH	USHANOV ST. 72, APT.53, UST-KAMENOGORSK, 070019 ,KAZAKHSTAN
5	POLYAKOV IVAN PETROVICH	LENIN AVE. 58/1, APT.12, UST-KAMENOGORSK, 070018,KAZAKHSTAN
6	RAGULIN BORIS ALEXANDROVICH	POBEDY AVE.11, APT. 46, UST-KAMENOGORSK, 070004, KAZAKHSTAN

PCT International Classification Number

C22C21/00; F16C33/06

PCT International Application Number

PCT/KZ2007/000004

PCT International Filing date

2007-03-27

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2006/1401.1	2006-12-20	Kazakhstan