Title of Invention

"A DIRECT SMELTING PROCESS AND APPARATUS"

Abstract

A direct smelting process and apparatus for producing iron and/or ferroalloys from a metalliferous material is disclosed. The process includes pre-treating metalliferous material by preheating, and optionally pre-reducing, metalliferous material in a pretreatment apparatus operating at essentially atmospheric pressure. The process also includes smelting pretreated metalliferous material to molten iron in a direct smelting vessel operating at essentially atmospheric pressure.

Full Text

A DIRECT SMELTING PROCESS AND APPARATUS The present invention relates to a process and an apparatus for producing iron and/or ferroalloys from metalliferous material, including iron ores, other ores containing iron such as chromite ores, partially reduced ores, and iron-containing waste streams such as steel reverts. The present invention relates particularly to a molten metal bath-based direct smelting process and an apparatus for producing molten iron and/or ferroalloys. One known molten bath-based direct smelting process for producing molten iron is the DIOS process. The DIOS process includes a pre-reduction stage and a smelt reduction stage. In the DIOS process iron ore (-8mm) is pre-heated (750°C) and pre-reduced (10 to 30%) in pressurised bubbling fluidised beds (typically 1-2 bar gauge pressure) using off gas from a pressurised smelt reduction vessel (also typically 1-2 bar gauge pressure) which contains a molten bath of iron and slag, with the slag forming a deep layer on the iron. The fine (-0.3mm) and coarse (-8 mm) components of the ore are separated in the pre-reduction stage of the process. The fine component is collected in a cyclone and injected into the smelt reduction vessel with nitrogen and the coarse component is charged by gravity from the top of the smelt reduction vessel. Pre-dried coal is charged directly to the smelt reduction vessel from the top of the vessel. The coal decomposes into char and volatile matter in the slag layer and the ore dissolves in the molten slag and forms molten FeO. The molten FeO is reduced at the slag/iron and slag/char interfaces to molten iron. Slag and iron are tapped periodically. The carbon monoxide generated at the iron/slag and slag/char interfaces generates a foaming slag. Oxygen is blown through a specially designed lance that extends into the foamed slag. The oxygen burns, ie post combusts, carbon monoxide that is generated with the smelting reduction reactions and thereby generates heat that is transferred first to the molten slag and then to molten iron by strong stirring of molten material within the bath by means of injected stirring gas. Stirring gas is injected into the hot iron bath from the bottom or side of the vessel. The use of stirring gas improves heat transfer efficiency and increases the slag/iron interface for reduction and therefore the vessel productivity and thermal efficiency. Another known direct smelting process for producing molten iron is the Romelt process. The Romelt process is based on the use of a large volume, highly agitated slag bath as a medium for smelting metalliferous material to iron in a smelt reduction vessel operated at more or less atmospheric pressure. The metalliferous material, coal, and fluxes are gravity fed into the slag bath via an opening in the top of the vessel. The Romelt process includes injecting a primary blast of oxygen-enriched air into the slag bath via a lower row of tuyeres to cause necessary slag agitation. The Romelt process also includes injecting a secondary blast of oxygen-enriched air or oxygen into the slag bath via an upper row of tuyeres to promote post-combustion of carbon monoxide that is generated within the slag bath. The molten iron produced in the slag bath moves downwardly and forms an iron layer and is discharged via a forehearth. In the Romelt process the iron layer is not an important reaction medium. Another known direct smelting process for producing molten iron is the AISI process. The AISI process includes a prereduction stage and a smelt reduction stage. Iron ore pellets are pre-heated and partially reduced in the prereduction stage and the preheated and prereduced iron ore pellets are then melted and completely reduced to molten iron in the smelt reduction stage. In the smelt reduction stage, the pre-heated and pre-reduced iron ore pellets from the pre-reduction stage, coal or coke breeze, and fluxes are top charged into a pressurised smelt reactor which contains a molten bath of iron and slag. The coal devolatilises in the slag layer and the iron ore pellets dissolve in the slag and then are reduced by carbon (char) in the slag. The process conditions result in slag foaming. Carbon monoxide and hydrogen generated in the process are post-combusted in or just above the slag layer and provide the energy required for the endothermic reduction reactions. Oxygen is top blown through a central, water cooled lance and nitrogen is injected through tuyeres at the bottom of the reactor to ensure sufficient stirring to facilitate heat transfer of the post-combustion energy to the bath. The process off gas is de-dusted in a hot cyclone before being fed to a shaft type furnace for pre-heating and pre-reduction of the pellets to FeO or wustite. Another known direct smelting process, which is generally referred to as the HIsmelt process, is described in a number of patent families, including International Application PCT/AU96/00197 (WO 96/31627), in the name of the applicant. The HIsmelt process as described in the International application in the context of producing molten iron includes: (a) forming a bath of molten iron and slag in a smelt reduction vessel; (b) injecting into the bath: (i) a metalliferous material, typically iron oxides; and (ii) a solid carbonaceous material, typically coal, which acts as a reductant of the iron oxides and a source of energy; and (c) smelting metalliferous material to iron in the metal layer. The HIsmelt process also includes post-combusting reaction gases, such as CO and H2 released from the bath, in the space above the bath with oxygen-containing gas and transferring the heat generated by the post-combustion to the bath to contribute to the thermal energy required to smelt the metalliferous material. The HIsmelt process also includes forming a transition zone above the nominal quiescent surface of the bath in which there is a favourable mass of ascending and thereafter descending droplets or splashes or streams of molten metal and/or slag which provide an effective medium to transfer to the bath the thermal energy generated by post-combustion of reaction gases above the bath. In the HIsmelt process metalliferous material and solid carbonaceous material are injected into the molten bath with a carrier gas through a number of lances/tuyeres which are inclined to the vertical so as to extend downwardly and inwardly through a side wall of the smelt reduction vessel and into a lower region of the vessel so as to deliver at least part of the solid material into the metal layer in the bottom of the vessel. A blast of hot air, which may be oxygen-enriched, is injected into an upper region of the vessel through a downwardly extending hot air injection lance to promote the post-combustion of reaction gases in the upper part of the vessel. Typically the hot air is at a temperature of the order of 1200°C and is generated in hot blast stoves. Off gases resulting from the post-combustion of reaction gases in the vessel are taken away from the upper part of the vessel through an off gas duct. The vessel includes refractory-lined water cooled panels in the side wall and the roof of the vessel, and water is circulated continuously through the panels in a continuous circuit. The HIsmelt process enables large quantities of molten iron, typically at least 0.5 Mt/a, to be produced by direct smelting in a single compact vessel. However, in order to achieve high molten iron production rates in the HIsmelt process it is necessary to (a) generate and transport large quantities of hot air and carrier gas (for solids injection) to the smelt reduction vessel, (b) transport large quantities of the metalliferous material, such as iron-containing feed materials, to the vessel, including generating and transporting large quantities of carrier gas to the vessel (c) transport large quantities of hot gases from the vessel, (d) transport large quantities of molten iron and slag produced in the process away from the vessel, and (e) circulate large quantities of water through the water cooled panels - all within a relatively confined area. In view of the above, high molten iron production rates require a HIsmelt plant that includes (a) a pressurised vessel and ancillary equipment such as lock hoppers for supplying solid feed materials to the vessel and pressure control equipment on the off gas duct of the vessel, (b) stoves that generate the high flowrate of hot air for the vessel, and (c) off gas treatment equipment that is capable of processing large quantities of off-gas discharged from the vessel. Construction of such a HIsmelt plant for smaller production rates, ie less than 0.5 Mt/a, would result in a relatively high capital cost per unit of production capacity. The present invention is an alternative HIsmelt process that specifically targets low capital cost at relatively low smelter capacities. The alternative HIsmelt process includes a smelt reduction stage that produces molten iron that operates at essentially atmospheric pressure and uses cold oxygen (or an air/oxygen mix) in place of a hot air blast. The term "essentially atmospheric pressure" in this context means that no specific effort is made to achieve gas-tight operation. Consequently, ingress (tramp) air is allowed to enter through various holes and gaps in the roof of the smelter and "immediate" afterburning of the off gas occurs. Moreover, it is not possible to recover fuel gas from smelter off gas in any meaningful way and heat capture (eg using steam tubes) in the off gas train is the only practical option for energy recovery. The alternative HIsmelt process also includes a metalliferous material pretreatment stage that preheats, and optionally prereduces, metalliferous material at essentially atmospheric pressure, as described above. According to the present invention there is provided a direct smelting process for producing iron and/or ferroalloys from a metalliferous material which includes the steps of: (a) supplying metalliferous material and carbonaceous material to a pretreatment apparatus and pretreating metalliferous material by preheating, and optionally prereducing, metalliferous material at essentially atmospheric pressure; and (b) supplying pretreated metalliferous material from step (a), solid carbonaceous material, and cold oxygen and/or a cold oxygen/air mixture to a smelt reduction vessel containing a molten bath of iron and slag and smelting metalliferous material to molten iron at essentially atmospheric pressure. The term "pre-reduction" in the context of optionally prereducing metalliferous material in step (a) means the degree to which oxygen is removed from iron ore, with Fe203 representing zero pre-reduction and metallic Fe representing 100% pre-reduction. Preferably step (a) includes pretreating metalliferous material by preheating and prereducing the material. Prereduction in step (a) may range from essentially zero to 80%. Pretreatment of metalliferous material in step (a) increases molten iron output in step (b) in the range of 1.4 to 5 times the output of a direct reduction vessel operating with cold unreduced ore and coal. In situations in which step (a) preheats only, the increased output is in the range of 1.4 to 1.8 times. In situations in which step (a) preheats and prereduces, the increased output is up to 5 times, depending on the degree of prereduction. The carbonaceous material supplied to step (a) may be solid or gaseous carbonaceous material. In situations in which carbonaceous material in the form of coal is used in step (a) there may be significant amounts of residual char mixed with the pretreated metalliferous material. The char may be left mixed with the pretreated metalliferous material and fed to the smelt reduction vessel with the material. Preferably step (a) includes supplying metalliferous material which has not been pre-agglomerated in any significant way (typically run-of-mine iron ore fines) to the pretreatment apparatus. However, the process extends to other forms of metalliferous material. For example, in some cases it may be necessary to pre-agglomerate metalliferous material because the starting material is too fine and would otherwise cause excessive dusting. Iron ore tailings from wash plants fall into this category. Preferably step (a) includes supplying metalliferous material to the pretreatment apparatus at essentially atmospheric pressure. Preferably step (a) includes releasing off-gas from the pretreatment apparatus via an off gas duct. Preferably the process includes recovering heat from the off gas. Preferably step (a) includes pretreating, and optionally prereducing, metalliferous material under conditions in which there is sufficient oxygen in the pretreatment apparatus to post-combust combustible gas, such as CO and H2, produced in step (a) so that off gas released from the pretreatment apparatus has no or minimal fuel gas value. Preferably off gas released from the pretreatment apparatus has less that 1.0 vol.% CO. Preferably off gas released from the pretreatment apparatus has free oxygen. Preferably step (b) includes supplying pretreated metalliferous material from step (a) into the smelt reduction vessel at essentially atmospheric pressure. Preferably step (b) includes supplying pretreated metalliferous material from step (a) into the smelt reduction vessel by gravity feeding the material into the vessel. Preferably step (b) includes supplying pretreated metalliferous material from step (a) into the smelt reduction vessel at a temperature in the range 250-1050°C. The lower limit of 250°C is a practical lower threshold temperature for driving off a significant proportion of water of crystallisation in iron ore. The upper limit of 1050°C is an upper threshold temperature at which operational problems with stickiness are likely to cause significant problems. More preferably step (b) includes supplying pretreated metalliferous material from step (a) into the smelt reduction vessel at a temperature in the range 750-950°C. Preferably step (b) includes releasing off gas from the smelt reduction vessel via an off gas duct. Preferably the process includes extracting off gas from the smelt reduction vessel by means of a fan or other suitable gas extraction device associated with the off gas duct. Preferably the process includes recovering heat from the off gas. Preferably step (b) includes post-combusting 40-80% of the combustible gases, such as CO and H2, released from the molten bath with cold oxygen and/or a cold oxygen/air mixture supplied to the smelt reduction vessel. Preferably step (b) includes supplying cold oxygen and/or a cold oxygen/air mixture into the smelt reduction vessel by injecting cold oxygen and/or cold oxygen/air mixture into the vessel via one or more than one oxygen gas injection. Preferably step (b) includes combusting at least a substantial part of the combustible gases released from the molten bath so that off gas released from the smelt reduction vessel has no or minimal fuel gas value. Typically, the at least substantially complete combustion is caused by post-combustion of combustible gases by cold air and/or cold oxygen/air mixture injected in the region of the bath surface and by after burning the remainder of the combustible gases with tramp air that enters the vessel. The use of the above-mentioned fan or other suitable gas extraction device associated with the off gas duct facilitates drawing sufficient tramp air into the vessel to achieve at least substantially complete combustion. Preferably off gas released from the smelt reduction vessel has less that 1.0 vol.% CO. Preferably off gas released from the smelt reduction vessel has free oxygen. Step (b) may include supplying pretreated metalliferous material from step (a) and/or solid carbonaceous material into the smelt reduction vessel by injecting metalliferous material and/or solid carbonaceous material, such as coal, and a carrier gas into the molten bath. Preferably step (b) includes supplying pretreated metalliferous material from step (a) and/or solid carbonaceous material into the smelt reduction vessel by injecting metalliferous material and/or solid carbonaceous material, such as coal, and a carrier gas into the molten bath through one or more than one injection lance and thereby generating an upward gas flow from the bath which causes: (i) formation of an expanded molten bath zone; and (ii) splashes, droplets and streams of molten material to be projected upwardly from the expanded molten bath zone. Preferably the lance or lances are downwardly and inwardly extending lance or lances. The carrier gas may be an oxidising or a non-oxidising gas. Preferably step (b) includes supplying solid carbonaceous material into the smelt reduction vessel by injecting solid carbonaceous material, such as coal, and a carrier gas into the molten bath through one or more than one injection lance. Preferably the carrier gas is an oxygen-containing gas. Preferably step (b) includes injecting solid carbonaceous material through one or more injection lance at a velocity in the range of 20-150 m/s. Preferably step (b) includes injecting at least 20 wt.% of the total amount of solid carbonaceous material supplied to the smelt reduction vessel through one or more than one injection lance. Step (b) may also include supplying additional solid carbonaceous material, such as lump coal, into the smelt reduction vessel by gravity feeding the material into the vessel. If both carbonaceous and metalliferous materials are injected at a high velocity, typically 20-50 m/s, via one or more than one injection lance into the molten bath (as is done under "normal" HIsmelt conditions), there may be excessive gas generation in the melt in terms of actual volumetric flow at smelter pressure. Excessive gas generation, if it occurs, could cause excessive eruption and unacceptable liquid carryover from the smelt reduction vessel. Accordingly, it is preferable to inject only solid carbonaceous feed at a high velocity, typically 20-50 m/s, into the molten bath and to gravity feed metalliferous material into the molten bath, for example through a suitable opening in the top of the smelt reduction vessel. In this way the process maintains gas flows (for transition zone generation) within an acceptable range for liquid eruption and splash creation. Depending on the nature of the feed materials and the precise method of operation, it may be necessary to inject a part only of the solid carbonaceous material into the molten bath at a high velocity, typically 20-50 m/s. In such a situation, preferably step (b) includes supplying the balance of the solid carbonaceous material to the smelt reduction vessel by gravity feeding the material into the vessel. According to the present invention there is also provided a direct smelting apparatus for producing iron and/or ferroalloys from a metalliferous material which includes: (a) a pretreatment apparatus for preheating and optionally pre-reducing metalliferous material at essentially atmospheric pressure; and (b) a smelt reduction vessel for smelting pretreated metalliferous material from the pretreatment apparatus to molten iron at essentially atmospheric pressure. The pretreatment apparatus may take a variety of forms and use a variety of fuels. One option for the pretreatment apparatus is a rotary kiln. Another option for the pretreatment apparatus is a fluidised bed. The fuels may be solid carbonaceous fuels, such as coal, and/or gaseous fuels, such as a gaseous hydrocarbon fuel. Preferably the apparatus further includes a means for transferring pretreated metalliferous material from the pretreatment apparatus to the smelt reduction vessel. Preferably the transfer means is a simple mechanical system which avoids the need for (hot) lock-hoppers and pneumatic conveying of material. Preferably the apparatus further includes a means for extracting off gas from the smelt reduction vessel. Preferably the process gas extraction means includes an induced-draft fan for drawing off gas from the vessel. Preferably the apparatus further includes a means for recovering heat from the extracted process gas. According to the present invention there is also provided iron and/or ferroalloys produced by the above-described process and apparatus. The present invention is described further by way of example with reference to the accompanying drawings, of which: Figure 1 illustrates in schematic form one embodiment of the present invention; and Figure 2 illustrates in schematic form another embodiment of the present invention. Figures 1 and 2 illustrate two, but not the only two, embodiments of the process and apparatus of the present invention. The embodiments include a pretreatment stage and a smelt reduction stage. The embodiments are described in the context of a metalliferous material in the form of iron ore and carbonaceous materials that are used in the pretreatment and smelt reduction stages. The present invention is not limited to these materials. With reference to Figure 1, iron ore, coal and air are fed to a pretreatment apparatus in the form of a rotary kiln in such a manner that the ore is pre-heated to around 750-950°C and is pre-reduced to around (typically) 50-60%. The rotary kiln is operated at essentially atmospheric pressure. Consequently, the rotary kiln does not have to be a pressure vessel and does not require ancillary equipment normally associated with pressure operation. Thus, the air in the rotary kiln includes tramp/ingress air that enters the kiln via openings in the kiln as well as deliberately supplied air. The hot, partially reduced product from the rotary kiln is fed directly into a smelt reduction vessel through an opening in the vessel by mechanical means, such as a hot bucket elevator. Alternatively, the rotary kiln may be positioned to facilitate direct gravity discharge from the kiln into the smelt reduction vessel through the opening in the vessel. Char remaining from devolatilisation and partial combustion of coal in the rotary kiln is present to some extent in the rotary kiln product and no attempt is made to separate the char from the metalliferous material. Combustible gases, such as CO and H2, in the rotary kiln are subjected to combustion within the kiln by tramp/ingress air and by deliberately supplied air. There is sufficient oxygen in the kiln so that there is at least substantially complete combustion in the kiln so that the resulting off gas discharged from the kiln via an off gas duct has no, or minimal, fuel gas value. Typically, the off gas contains some free oxygen and less than 1% CO. The off gas discharged from the rotary kiln may be used for steam generation or simply disposed of (eg by water quench), depending on the relative value of this energy. The smelt reduction vessel contains a molten bath of iron and slag. The vessel is operated at a slightly negative pressure in this embodiment of the present invention. Consequently, the vessel does not have to be a pressure vessel and does not require ancillary equipment normally associated with pressure operation. In addition to the rotary kiln product that is supplied as a feed material to the smelt reduction vessel, coal and cold oxygen are injected as additional feed materials into the vessel. The coal and a carrier gas are injected at a velocity in the range of 20-150 m/s into the molten bath through one or more lances that extend into the vessel, such as downwardly through a side wall of the vessel, so as to generate an upward gas flow from the bath within the vessel which causes: (i) formation of an expanded molten bath zone; and (ii) splashes, droplets and streams of molten material upwardly from the expanded molten bath zone. Typically, the intensity of the upward gas flow is less than that produced when all of the solid feed materials are injected via the solids injection lances in the side walls of the vessel. Nevertheless, the upward gas flow is sufficient to ensure bath turnover that facilitates efficient heat transfer to the molten bath. At least 20 wt.% of the coal required by the smelt reduction vessel is injected via the lance or lances. The carrier gas for coal injection may be any suitable gas. Suitable carrier gases are not confined to inert gas and include oxygen-containing gases. The cold oxygen is injected into an upper region of the smelt reduction vessel via at least one downwardly extending lance. The injected cold oxygen gas post-combusts 40-80% of the combustible gases released from the molten bath and thereby generates heat. The above-described turning over of the bath caused by upward gas flow from the bath facilitates heat transfer to the bath that is required to maintain the reactions in the vessel. The remaining combustible gases released from the molten bath are after burned by tramp air drawn into the upper region of the vessel. The overall result is that there is at least substantially complete combustion of combustible gases produced in the vessel so that the off gas discharged from the vessel via an off gas duct has no, or minimal, fuel gas value. In other words, there is sufficient oxygen in the vessel to ensure combustion of CO and H2. Typically, the off gas has some free oxygen and less than 1% CO. The metalliferous material in the rotary kiln product that is supplied to the smelt reduction vessel is melted and completely reduced to molten iron in the molten bath in the smelt reduction vessel. Molten iron is discharged periodically or continuously from the smelt reduction vessel. In addition, slag is discharged periodically or continuously from the smelt reduction vessel. In addition, the off gas generated in the smelt reduction vessel is extracted from the vessel by means of an induced draft fan operatively associated with the off gas duct and is processed in a waste recovery unit to recover heat from the gas. The use of the fan facilitates operation of the process at a slightly negative pressure and assists in drawing in tramp air into the vessel that enables at least substantially complete combustion of combustible gases in the vessel. The embodiment shown in Figure 2 is similar to the embodiment shown in Figure 1. The main difference between the embodiments is that a fluidised bed operating with natural gas as a carbonaceous material rather than a rotary kiln operating with coal as a carbonaceous material is used for the pretreatment stage of the process. With reference to Figure 2, a hydrocarbon fuel such as natural gas (or fuel oil or other suitable fuel) is burned with air in a fluidised bed of iron ore at around 750-950°C. The fluidised bed operates at essentially atmospheric pressure. The natural gas is completely burned and a small amount of free oxygen (eg 1% 02) is maintained in the off gas. The incoming ore feed to the fluidised bed is preheated by outgoing off gas from the fluidised bed. The fluidised bed product is hot iron ore with little or no pre-reduction. It is discharged from the fluidised bed and fed directly into the smelt reduction vessel through an opening in the roof thereof by simple non-pneumatic means (as in the previous example). One other difference between the embodiments is that there is no char from the fluidised bed that can contribute to the carbonaceous material requirements for the smelt reduction vessel and coal is used as the entire carbonaceous feed to the smelt reduction vessel. Part of the coal is injected into the smelt reduction vessel via downwardly and inwardly extending lances, as described in relation to the previous embodiment. The remainder of the coal is gravity fed into the smelt reduction vessel through an opening in the roof of the vessel. A key attribute of the above-described embodiments is simplicity, leading to cost-effective operation at low production capacities. For example, all of the above pretreatment apparatus, including rotary kilns and fluidised beds, operate at essentially atmospheric pressure and all avoid the need for pressurised lock-hoppers (and other devices necessary to manage materials in a pressurised process). In addition, the transfer means between the pretreatment apparatus and the smelt reduction vessel can be any simple mechanical system which avoids the need for (hot) pressurised lock-hoppers and pneumatic conveying. Many modifications may be made to the embodiments of the present invention described above without departing from the spirit and scope of the invention. By way of example, whilst the embodiments include rotary kilns and fluidised beds as pretreatment apparatus, the present invention is not so limited and extends to any means for pretreating iron ore by preheating and optionally prereducing iron ore at essentially atmospheric pressure. Specifically, there are various other options for preheating and optionally prereducing metalliferous material including rotary hearth and multi-hearth furnaces. An induction fan may also be used to draw hot smelter offgas through counter-current cyclones. In addition, whilst the above embodiments include operating the smelt reduction vessel at a slightly negative pressure, the present invention is not so limited and extends to operating at atmospheric pressure. We Claim: 1. A direct smelting process for producing iron and/or ferroalloys from a metalliferous material having the steps of supplying metalliferous material and carbonaceous material to a pre-treatment apparatus characterized by pre-treating metalliferous material by preheating, and optionally pre-reducing, said metalliferous material at essentially atmospheric pressure to obtain pre-treated metalliferous material; and supplying said pre-treated metalliferous material, solid carbonaceous material, and cold oxygen and/or a cold oxygen/air mixture to a smelt reduction vessel containing a molten bath of iron and slag and smelting metalliferous material to molten iron at essentially atmospheric pressure. 2. The process as claimed in claim 1 wherein said pre-treating of metalliferous material is by preheating and pre-reducing the material. 3. The process as claimed in claim 1 wherein said pre-treating of metalliferous material is by preheating and pre-reducing the material up to 80%. 4. The process as claimed in any one of the preceding claims wherein metalliferous material is pre-treated to obtain pre-treated metalliferous material and char. 5. The process as claimed in claim 4 wherein the pre-treated metalliferous material and char is supplied into the smelt reduction vessel. 6. The process as claimed in any one of the preceding claims wherein the metalliferous material supplied to said pre-treatment apparatus has not been pre-agglomerated in any significant way. 7. The process as claimed in any one of the preceding claims wherein the metalliferous material is supplied to the pre-treatment apparatus at atmospheric pressure. 8. The process as claimed in any one of the preceding claims wherein off-gas is released from the pre-treatment apparatus. 9. The process as claimed in any one of the preceding claims wherein the metalliferous material is pre-treated and reduced under conditions in which there is sufficient oxygen in the pre-treatment apparatus to post-combust combustible gas such as CO and H2, produced in pre-treatment so that off-gas released from the pre-treatment apparatus has no or minimal fuel gas value. 10. The process as claimed in claim 9 wherein off-gas released from the pre- treatment apparatus has free oxygen and less that 1.0 vol. % CO. 11. The process as claimed in any one of the preceding claims wherein said pre-treated metalliferous material is supplied into the smelt reduction vessel at essentially atmospheric pressure. 12. The process as claimed in any one of the preceding claims wherein said pre-treated metalliferous material is supplied into the smelt reduction vessel by gravity feeding the material into the vessel. 13. The process as claimed in any one of the preceding claims wherein said pre-treated metalliferous material is supplied into the smelt reduction vessel at a temperature in the range 250-1050°C. 14. The process as claimed in any one of the preceding claims wherein said pre-treated metalliferous material is supplied into the smelt reduction vessel at a temperature in the range 750-950°C. 15. The process as claimed in any one of the preceding claims wherein off-gas is released from the smelt reduction vessel. 16. The process as claimed in claim 15 wherein off-gas is extracted from the smelt reduction vessel. 17. The process as claimed in claim 16 wherein heat is recovered from the off-gas. 18. The process as claimed in any one of the preceding claims wherein 40-80% of the combustible gases such as CO and H2, released from the molten bath is post-combusted with cold oxygen and/or a cold oxygen/air mixture supplied to the smelt reduction vessel. 19. The process as claimed in any one of the preceding claims wherein cold oxygen and/or a cold oxygen/air mixture is supplied into the smelt reduction vessel by injecting cold oxygen and/or cold oxygen/air mixture into the vessel via one or more than one oxygen gas injection lance. 20. The process as claimed in claim 18 wherein at least a substantial part of the combustible gases released from the molten bath is combusted so that off-gas released from the smelt reduction vessel has no or minimal fuel gas value. 21. The process as claimed in claim 20 wherein off-gas released from the smelt reduction vessel has free oxygen and less than 1.0 vol.% CO. 22.' The process as claimed in any one of the preceding claims wherein said pre-treated metalliferous material and/or solid carbonaceous material are supplied into the smelt reduction vessel by injecting metalliferous material and/or solid carbonaceous material, such as coal, and a carrier gas into the molten bath through one or more than one injection lance and thereby generating an upward gas flow from the bath which causes: (i) formation of an expanded molten bath zone; and (ii) splashes, droplets and streams of molten material to be projected upwardly from the expanded molten bath zone. 23. The process as claimed in claim 22 wherein the carrier gas is an oxidising or a non-oxidising gas. 24. The process as claimed in any one of the preceding claims wherein solid carbonaceous material is supplied into the smelt reduction vessel by injecting solid carbonaceous material, such as coal, and a carrier gas into the molten bath through one or more than one injection lance. 25. The process claimed in claim 24 wherein the carrier gas is an oxygen-containing gas. 26. The process as claimed in claim 24 or claim 25 wherein solid carbonaceous material is injected through one or more injection lance at a velocity in the range of 20-150 m/s. 27. The process as claimed in any one of claims 24 to 26 wherein at least 20 wt. % of the total amount of solid carbonaceous material supplied to the smelt reduction vessel is injected through one or more than one injection lance. 28. The process as claimed in any one of the preceding claims wherein solid carbonaceous material, such as lump coal, is supplied into the smelt reduction vessel by gravity feeding the material into the vessel. 29. The process as claimed in any one of the preceding claims wherein part of the solid carbonaceous material is supplied into the smelt reduction vessel by gravity feeding the material into the vessel and a part of the solid carbonaceous material is supplied into the smelt reduction vessel by injecting the material into the vessel via one or more than one injection lance. 30. A direct smelting apparatus for producing iron and/or ferroalloys from a metalliferous material, said apparatus having: (a) a pre-treatment apparatus for preheating and optionally pre- ' reducing metalliferous material at essentially atmospheric pressure; and (b) a smelt reduction vessel for smelting pre-treated metalliferous material from the pre-treatment apparatus to molten iron at essentially atmospheric pressure. 31. The apparatus as claimed in claim 30 wherein the pre-treatment apparatus is provided with a rotary kiln or a fluidised bed. 32. The apparatus as claimed in claim 30 or claim 31 wherein a means is present for transferring pre-treated metalliferous material from the pre-treatment apparatus to the smelt reduction vessel. 33. The apparatus as claimed in any one of claims 30 to 32 wherein a means is present for extracting off-gas from the smelt reduction vessel. 34. The apparatus as claimed in claim 33 wherein the off-gas extraction means is provided with an induced-draft fan for drawing off-gas from the vessel. 35. The apparatus as claimed in claim 33 or claim 34 wherein a means is present for recovering heat from the extracted process gas.

Documents:

1615-DEL-2005-Abstract-(16-09-2011).pdf

1615-del-2005-abstract.pdf

1615-DEL-2005-Claims-(16-09-2011).pdf

1615-DEL-2005-Claims-(21-05-2012).pdf

1615-del-2005-claims.pdf

1615-del-2005-Correspondence Others-(12-04-2012).pdf

1615-DEL-2005-Correspondence Others-(16-09-2011).pdf

1615-DEL-2005-Correspondence Others-(21-05-2012).pdf

1615-DEL-2005-Correspondence Others-(22-03-2011).pdf

1615-DEL-2005-Correspondence Others-(27-10-2011).pdf

1615-del-2005-correspondence-others.pdf

1615-del-2005-correspondence-po.pdf

1615-del-2005-description (complete).pdf

1615-del-2005-drawings.pdf

1615-del-2005-form-1.pdf

1615-del-2005-form-18.pdf

1615-del-2005-form-2.pdf

1615-del-2005-Form-3-(12-04-2012).pdf

1615-DEL-2005-Form-3-(22-03-2011).pdf

1615-del-2005-form-3.pdf

1615-del-2005-form-5.pdf

1615-DEL-2005-GPA-(22-03-2011).pdf

1615-del-2005-gpa.pdf