Title of Invention	AN IMPROVED PROCESSES FOR EXTRACTION OF ALKALINE EARTH OXIDE PHASES IN CERAMIC MATERIALS
Abstract	An improved process for the extraction of alkaline earth oxide phases in ceramic materials,, which comprises preparaing an alcoholic solution containing 0.5 to 1.5 wt% water and 0.5 wt% hydroxylamine hydrochloride, mixing powdered ceramic material of size below 52µm containing MgO in the range of 35 to 98% and CaO in the range of 0 to 60% to ammonium nitrate solution in such a way that the ratios of ammonium nitrate : alcohol : ceramic material is in the ranges of 12 gms : 200 ml : 5 gms to 20 gms : 300 ml : 5 gms, refluxing the mixture at a temperature range of 60 to 70°C for a period in the range of 10 minutes to 15 hrs., filtering the resultant solution to separate the alkaline earth oxide phases.

Title of Invention

AN IMPROVED PROCESSES FOR EXTRACTION OF ALKALINE EARTH OXIDE PHASES IN CERAMIC MATERIALS

Abstract

An improved process for the extraction of alkaline earth oxide phases in ceramic materials,, which comprises preparaing an alcoholic solution containing 0.5 to 1.5 wt% water and 0.5 wt% hydroxylamine hydrochloride, mixing powdered ceramic material of size below 52µm containing MgO in the range of 35 to 98% and CaO in the range of 0 to 60% to ammonium nitrate solution in such a way that the ratios of ammonium nitrate : alcohol : ceramic material is in the ranges of 12 gms : 200 ml : 5 gms to 20 gms : 300 ml : 5 gms, refluxing the mixture at a temperature range of 60 to 70°C for a period in the range of 10 minutes to 15 hrs., filtering the resultant solution to separate the alkaline earth oxide phases.

Full Text	This invention, relates to an improved process for the extraction of alkaline earth oxide phases in ceramic materials. The present invention particularly relates to an improved process for the extraction of alkaline earth oxide phases in ceramic materials containing magnesia, MgO and calcia, CaO such as cement , sintered magnesite, dolomite, magnesite-chrome and magnesia-carbon having MgO contents ranging from 35 - 98% and CaO contents ranging from 0 - 60%. This invention mainly provides an improved process for the extraction of alkaline earth oxide phases in burnt or fired ceramic materials which contain MgO as periclase phase or CaO as lime phase. The MgO content ranges from 35 - 98% and the CaO as lime phase. The MgO content ranges from 35 - 98% and the CaO content ranges from 0 - 60% by mass in the material and includes impurities that contain any or all, but not limited to, the following oxides in chemical or physical mixed state; CaO, MgO, SiO2, A12O3, Fe2O3, TiO2, Cr2O3, B2O3, K2O and Na2O. Ceramic materials find wide spread use in various industries and the refractory group of ceramic materials has emerged as an important area for application in high temperature kilns and furnaces. Stringent quality control and increased output demands in metallurgical, cement, and other energy intensive industries have created the need for highly reliable ceramic lining materials for application at high temperatures. This has in turn led to production of high quality ceramic materials for high temperature use, known in the field as refractory materials, with controlled impurity contents. The impurities, known in the field as secondary or minor phases, are present in small quantities generally amounting to not more than 5/.. These secondary phases give rise to critical liquid farming temperatures during use of the said refractory material which in turn controls the safe use limits of the refractory material. It is therefore, imperative that the said refractory materials be evaluated for the impurity content and the information thus obtained may be used in a manner as desirable for prediction or evaluation of the quality and usefulness of the material under investigat ion. In the field of refractory materials, the basic group of refractories comprising materials bearing oxides of the elements magnesium and calcium, singly, in combination or in asssociation with other oxides of elements such as, but not limited to, silicon, aluminium and chromium or in association with elements such as carbon are used to line kilns, furnaces and heating units. These basic refractory materials are especially sensitive to the presence of impurities such as but not limited to the oxides of the elements silicon, aluminium, iron, titanium, chromium , boron, sodium, potassium and calcium. These oxide impurities known as secondary or minor phases may occur in physically or chemically mixed state in crystalline or glassy form, with the primary oxide or oxides for example oxide impurities of magnesium silicate known as forsterite; calcium magnesium silicate known as mohticellite or merwinite depending on the nature and composition; calcium silicate either in crystalline or glassy state? magnesium aluminate or chromate, known as spinels; magnesium ferrite known as magnesia ferrite; calcium ferrite or alumino ferrite. The use of mixtures of basic oxides of alkaline earth elements such as magnesium with oxides of refractory and non-refractory metals, such as chromium and carbon is another class of basic refractories. In these refractories a portion of the alkaline earth element oxide, e.g. MgO may react with the addition such as the oxides of chromium to give spinel phases of magnesium chromate. It is important that the extent of this reaction be evaluated to predict the behaviour of the material. In the case of refractories based on mixers of the oxides of element of the alkaline earth oxide, for example of magnesium and calcium, known in the practice as dolomite or mag-dolo, the primary phases are magnesium oxide and calcium oxide present as pet-iclase and lime phases respectively. These primary phases combine with impurity elements and their oxides to give secondary phases or minor phases as given earlier in this specification. It is necessary to provide information regarding these secondary phases to evaluate the usefulness of the material as a refractory material for application in thermal units. Methods for extracting periclase in refractories is not well reported. The one.proposed by Bague and Taylor for free MgO extraction in cement is the only available method. According to their method, cement samples, are refluxed with 60mL of 5:1 Ethanol-Glycerol solvent and 4gms of ammonium nitrate for 3 to 4 hours. The extracted MgO is filtered and estimated. However this method has certain drawbacks, like the extraction is not phase specific as it always accompanies some of the free CaO as well. Moreover the presence of glycerol as one the solvents complicates the complexometric estimation of periclase phase. Two ASTM methods, one by Lerch and Bogue and the other by Franke have been widely used for the determination of free lime in cement system. In the First method free lime is extracted by 5 : 1 ethanol - glycerol solvent mixture and titrated insitu against standard ammonium acetate. In the Franke method, free lime is titrated against standard perchloric acid after extraction with 3 : 20 acetoacetic - ester and isobutyi alcohol solvent mixture. These_ methods are tedious to perform and requires about 3 to 4 hours for complete extraction. The main object of the present invention is to provide an improved process for the extraction of alkaline earth oxide phases in ceramic materials which obviates the above noted drawbacks. An objective of the present invention is to provide an improved process to extract a major portion of periclase phase, MgO, in sintered magnesite material so as to enable isolation of secondary and minor phases. Another object of the present invention is to provide an improved process to extract a major portion of lime, CaO and periclase, MgO phases in stages from sintered dolomite and mag-dolo material so as to enable isolation of primary, secondary and minor phases. Yet another object of the present invention is to provide an improved process to extract a major portion of MgO present as periclase phase in magnesia-bearing carbon-magnesia materials to recover primary, secondary and minor phases. Still another object of the present invention is to provide an improved process for the extraction of a major portion of MgO present as periclase phase in magnesia-bearing chromia-magnesia materials to recover primary, secondary -and minor phases. After conducting considerable research in this area uie have observed that magnesium oxide present as periclase phase and calcium oxide phase present as lime in refractory materials can be^ selectively dissolved from a matrix of refractory oxides. It has also been found that this dissolution is limited to magensium oxide which is not (chemically combined with oxides of other elements and is further limited to calcium oxide which is not chemically combined with oxides of other elements. This characteristics permits isolation of primary, secondary and minor phases in a number of basic refractory materials by selective extraction of phases. Accordingly, the present invention provides an improved process for the extraction of alkaline earth oxide phases in ceramic materials, which comprises preparaing an alcoholic solution containing 0.5 to 1.5 wt% water and 0.5 wt% hydroxylamine hydrochloride, mixing powdered ceramic material of size below 52um containing MgO in the range of 35 to 98% and CaO in the range of 0 to 60% to ammonium nitrate solution in such a way that the ratios of ammonium nitrate : alcohol: ceramic material is in the ranges of 12 gms : 200 ml: 5 gms to 20 gms : 300 ml: 5 gms, refluxing the mixture at a temperature range of 60 to 70°C for a period in the range of 10 minutes to 15 hrs., filtering the resultant solution to separate the alkaline earth oxide phases. In an embodiment of the invention, the alcohol used may be in the form of absolute ethanol, distilled rectified spirit. The present invention provides an improved method for the isolation of primary, secondary and minor phases from basic refractory materials using organic and inorganic chemicals and apparatus used in chemistry practice. The methods used a salt, ammonium nitrate, which reacts with magnesium and calcium oxide present in the material to be investigated to produce magnesium ammonium nitrate or calcium ammonium nitrate or both as the case may be. The salt, ammonium nitrate, is dissolved in alcohol, ethyl alcohol, prior to the reaction with the material to be investigated. The invention utilise less number of raw material input over the existing Bogue-Taylor technique for Mgo extraction but at the same time.the efficiency of this new invention is comparable and processes are simple and rapid over the existing methods- For the same, amount of MgO extraction, the total time required in Bogue-Taylor method' is about 135 minutes while it is about 45 minutes for this technique. In the case of CaQ and portlandite extraction in cement materials the new invention requires about 15 minutes whereas the standard ASTM technique requires about 4 hours. The refractory material is powdered in a suitable manner, such as using a hard agate mortar and pestle, to a sufficiently fine size, such as below 52mm. This powdered material is mixed with the alcoholic solution of ammonium nitrate salt. In the invention, appropriate ratios of the ammonium nitrate salt, the ethyl alcohol solvent and the refractory material were used as given in the examples.The entire mixture is heated under repeated bailing at a temperature" in the range of 60 C to 70 C in apparatus such as a refluxing assembly consisting of a flat bottom short neck glass Erlenmeyer flask with a water coaled glass refluxing condenser. The capacity of the flask and of the condenser may be appropriatly _ chosen, e.g. far 5g. sintered magnesite, 300mL of alcohol, is used, the flask has capacity of at least 500mL and the condenser has a length of at least 300mm.-The flask is heated,using a heating device such as electrical heating mantle and the heating rate and energy input is controlled using an appropriate device such as an electrical variable resistance energy regulator. The apparatus is de.signed to permit removal of matter at intervals by opening standard tapered ground glass joints which are refitted upon completion of removal. The residual liquid and solid material is filtered through a filtering device, such as a glass funnel lined with a filter paper with the choice of a suitable opening for optimum speed of filtration without loss of solid matter into the separated liquid. The solid residue obtained upon filtration contains the minor/secondary phases while the filtrate contains the major CaO and MgO phases. It is observed that the rate of dissolution of the major phases like periclase and calcia from the matrix of oxides can be controlled by controlling the time of refluxing, and volume of ethyl alcohol solvent. Additionally, the use of a low amount of water and of hydroxylamine hydrochloride as given in the examples hereunder are used to accelerate the rate of dissolution of periclase phase from the ceramic material. The amount of periclase and calcia phases can be extracted from the various refractory materials are given in the Table I. Table I (Table Removed) The method of dissolving or extracting particular phase or phases from refractory materials has proved to be an excellent method of isolating primary, secondary and minor phases in ceramic materials. The process of the invention is illustrated by the follwing examples which should not, however, be construed to limit the scope of the invention. Example 1 5g. sample of natural magnesite from Salem, Tamil Nadu is sintered at 1650 C with one hour soaking in an electrical kiln. The sintered magnesite is powdered to -52mm termed A using an agate mortar and pestles. 20g of dry ammonium nitrateV^R/BRgrade., is dissolved in 300mL of pure ethanol containing less than 0.5/. water to give a solution termed B. The powder A is added to the solution B and the mixture is placed in a 500mL Erlenmeyer flask and r«efluxed for 9 hours at 70 C to give a new solution C with the solid residue. This solution C is filtered to separate the residue termed D and the filtrate termed E. It is found that 86 /♦ of MgO present in A is removed in D thereby permitting isolation of secondary phases in D by removing major portion of primary phase periclase in A. Analysing the filtrate E, no presence of elements Ca, Al, Si, Fe and Ti which were present in A were found indicating that only MgO was dissolved from A due to the process indicated in the invention. From phase analysis of powder A and residue D it is apparent that periclase phase has been removed by decrease in MgO reflections (200) and (111) and increase in mont icel .1 i te reflections (131), (130) and (111). Ex amp le 2 5g. sample of natural magnesite from Salem, Tamil Nadu is sintered at 1650 C with one hour soaking in an electrical kiln. i The sintered magnesite is powdered to --52mm termed A using an agate mortar and pestles. 20q of dry ammonium nitrate,'AR/GRgrade, is dissolved in 300mL of pure ethanol containing less than O.5%, water to give a solution termed B. The powder A is added to the solution B and the mixture is placed in a 500ml Enlenmeyer flask and subjected o for varying refluxing time at 70 C to give a new solution C with the solid residue. This solution C is filtered to separate the residue termed D and the filtrate termed E. It is found that the dissolution of periclase is controlled by controlling the refluxing time as shown in the Table II below. Table II (Table Removed) Example- 3 5g. sample of natural magnesite from Salem, Tamil Nadu. is sintered at 1650 C with one hour soaking in an electrical kiln. The sintered magnesite is powdered to ~52u. termed A using an agate mortar and pestles. 20g of dry ammonium nitrate, AR/GRgrade, is dissolved in 300ml_ of pure ethanol containing 1.5% water to give a solution termed B. The powder A is added to the solution B and the mixture is placed in a 500ml_ Erlenmeyer flask and refluxed for 9 hours at 70 C to give a new solution C with the solid residue. This solution C is filtered to separate the residue termed D and the filtrate termed E. It is found that 28 V, of MgD present in A is removed in D in three hours. Examplef-4 5g. sample of natural magnesite from Salem, Tamil Nadu is sintered at 1650 C with one hour soaking in an electrical kiln. The sintered magnesite is powdered to -52u termed A Losing an agate mortar and pestles. 20g of dry ammonium nitrate, AR/GRgrade, is dissolved in 300mL of pure ethanol containing 1.5Y. water and 0.5gm hydroxylamine hydrochloride to give a solution termed B. The powder A is added to the solution B and the mixture is placed in a 500mL Erlenmeyer flask and refluxed for 9 hours at 70 C to give a new solution C with the solid residue. This solution C is filtered to separate the residue termed D arid the filtrate termed E. It is found that 68 % of MgO present in A is removed in D in three hours. Example-5 5g. sample of natural magnesite from Salem, Tamil Nadu is sintered at 1650°C with one hour soaking in an electrical kiln. The sintered magnesite is powdered to -52u termed A using an agate mortar and pestles. 20g of dry ammonium nitrate, AR/GRgrade, is dissolved in SOOmL of pure ethanol containing 0.5% water and 0.5gm of hydroxylamine hydrochloride to give a solution termed B. The powder A is added to the saluti.on B and the mixture is placed in a SOOmL Erlenmeyer flask and refluxed for 9 hours at 70 C to give a new solution C with the solid residue. This solution C is filtered to separate the residue termed D and the filtrate termed E. It is found that 36 /♦ of MgO present in A is removed in D in three hours. Example-6 5 g sample of dolomite material is sintered to 1650 C. The sintered dolomite material is powdered to -52 u termed F using an agate mortar and pestle. 12g of dry ammonium nitrate, AR/GR grade, is dissolved in 200 mL of pure ethanol containing less than 0.5'/» water to give a solution termed B. The powder F is added to the solution B and the mixture is placed in a 500 mL Erlenmeyer flask and refluxed for 10 minutes at 70 C to give a new solution G with the solid residue. This solution G is filtered to separate the residue termed H and the filtrate termed I. It is found that 60% of CaO present in F is removed in H thereby permitting isolation of primary and secondary phases in H by removing major portion of primary phase lime in F. Analysing the filtrate I, no presence of elements Mg, Al, Si, Fe and Ti which were present in F were found indicating that only CaO was dissolved from F due to the process indicated in the invention. From phase analysis of powder F and residue H it is apparent that lime phase has been removed substantially.. The advantages of the present invention are s 1, a cheaper process than existing techniques due to reduced raw materials input and manpower. 2. a reduced processing time of,30 to 60% compared to existing processes through the developed technique. a process by which uncombined alkaline earth oxides magnesia and calcia are separately leached out from ceramic material which is stbpped so as to provide a material free of calcia or free of calcia and magnesia or intermeadiate stage thereof hitherto not attempted. We Claim: 1. An improved process for the extraction of alkaline earth oxide phases in ceramic materials, which comprises preparaing an alcoholic solution containing 0.5 to 1.5 wt% water and 0.5 wt% hydroxylamine hydrochloride, mixing powdered ceramic material of size below 52µm containing MgO in the range of 35 to 98% and CaO in the range of 0 to 60% to ammonium nitrate solution in such a way that the ratios of ammonium nitrate : alcohol: ceramic material is in the ranges of 12 gms : 200 ml : 5 gms to 20 gms : 300 ml : 5 gms, refluxing the mixture at a temperature range of 60 to 70°C for a period in the range of 10 minutes to 15 hrs., filtering the resultant solution to separate the alkaline earth oxide phases. 2. An improved process as claimed in claims 1 & 2 wherein the alcohol used is selected from absolute ethanol, distilled rectified spirit. 3. An improved process for the selective extraction of alkaline earth oxide phases in ceramic materials substantially as herein described with reference to the examples.

Full Text

This invention, relates to an improved process for the extraction of alkaline earth oxide phases in ceramic materials.
The present invention particularly relates to an improved process for the extraction of alkaline earth oxide phases in ceramic materials containing magnesia, MgO and calcia, CaO such as cement , sintered magnesite, dolomite, magnesite-chrome and magnesia-carbon having MgO contents ranging from 35 - 98% and CaO contents ranging from 0 - 60%.
This invention mainly provides an improved process for the extraction of alkaline earth oxide phases in burnt or fired ceramic materials which contain MgO as periclase phase or CaO as lime phase. The MgO content ranges from 35 - 98% and the CaO as lime phase. The MgO content ranges from 35 - 98% and the CaO content ranges from 0 - 60% by mass in the material and includes impurities that contain any or all, but not limited to, the following oxides in chemical or physical mixed state; CaO, MgO, SiO2, A12O3, Fe2O3, TiO2, Cr2O3, B2O3, K2O and Na2O.
Ceramic materials find wide spread use in various industries and the refractory group of ceramic materials has emerged as an important area for application in high temperature kilns and furnaces. Stringent quality control and increased output demands in metallurgical, cement, and other energy intensive industries have created the need for highly reliable ceramic lining materials for application at high temperatures. This has in turn led to production of high quality ceramic materials for high temperature use, known in the field as refractory materials, with controlled impurity contents. The

impurities, known in the field as secondary or minor phases, are
present in small quantities generally amounting to not more than
5*/.. These secondary phases give rise to critical liquid farming
temperatures during use of the said refractory material which in
turn controls the safe use limits of the refractory material. It
is therefore, imperative that the said refractory materials be
evaluated for the impurity content and the information thus
obtained may be used in a manner as desirable for prediction or
evaluation of the quality and usefulness of the material under
investigat ion.
In the field of refractory materials, the basic group of refractories comprising materials bearing oxides of the elements magnesium and calcium, singly, in combination or in asssociation with other oxides of elements such as, but not limited to, silicon, aluminium and chromium or in association with elements such as carbon are used to line kilns, furnaces and heating units. These basic refractory materials are especially sensitive to the presence of impurities such as but not limited to the oxides of the elements silicon, aluminium, iron, titanium, chromium , boron, sodium, potassium and calcium. These oxide impurities known as secondary or minor phases may occur in physically or chemically mixed state in crystalline or glassy form, with the primary oxide or oxides for example oxide impurities of magnesium silicate known as forsterite; calcium magnesium silicate known as mohticellite or merwinite depending on the nature and composition; calcium silicate either in crystalline or glassy state? magnesium aluminate or chromate,

known as spinels; magnesium ferrite known as magnesia ferrite; calcium ferrite or alumino ferrite.
The use of mixtures of basic oxides of alkaline earth elements such as magnesium with oxides of refractory and non-refractory metals, such as chromium and carbon is another class of basic refractories. In these refractories a portion of the alkaline earth element oxide, e.g. MgO may react with the addition such as the oxides of chromium to give spinel phases of magnesium chromate. It is important that the extent of this reaction be evaluated to predict the behaviour of the material.
In the case of refractories based on mixers of the oxides of element of the alkaline earth oxide, for example of magnesium and calcium, known in the practice as dolomite or mag-dolo, the primary phases are magnesium oxide and calcium oxide present as pet-iclase and lime phases respectively. These primary phases combine with impurity elements and their oxides to give secondary phases or minor phases as given earlier in this specification. It is necessary to provide information regarding these secondary phases to evaluate the usefulness of the material as a refractory material for application in thermal units.
Methods for extracting periclase in refractories is not well reported. The one.proposed by Bague and Taylor for free MgO extraction in cement is the only available method. According to their method, cement samples, are refluxed with 60mL of 5:1 Ethanol-Glycerol solvent and 4gms of ammonium nitrate for 3 to 4 hours. The extracted MgO is filtered and estimated. However this

method has certain drawbacks, like the extraction is not phase specific as it always accompanies some of the free CaO as well. Moreover the presence of glycerol as one the solvents complicates the complexometric estimation of periclase phase. Two ASTM methods, one by Lerch and Bogue and the other by Franke have been widely used for the determination of free lime in cement system. In the First method free lime is extracted by 5 : 1 ethanol - glycerol solvent mixture and titrated insitu against standard ammonium acetate. In the Franke method, free lime is titrated against standard perchloric acid after extraction with 3 : 20 acetoacetic - ester and isobutyi alcohol solvent mixture. These_ methods are tedious to perform and requires about 3 to 4 hours for complete extraction.
The main object of the present invention is to provide an improved process for the extraction of alkaline earth oxide phases in ceramic materials which obviates the above noted drawbacks.
An objective of the present invention is to provide an improved process to extract a major portion of periclase phase, MgO, in sintered magnesite material so as to enable isolation of secondary and minor phases.
Another object of the present invention is to provide an improved process to extract a major portion of lime, CaO and periclase, MgO phases in stages from sintered dolomite and mag-dolo material so as to enable isolation of primary, secondary and minor phases.

Yet another object of the present invention is to provide an improved process to extract a major portion of MgO present as periclase phase in magnesia-bearing carbon-magnesia materials to recover primary, secondary and minor phases.
Still another object of the present invention is to provide an improved process for the extraction of a major portion of MgO present as periclase phase in magnesia-bearing chromia-magnesia materials to recover primary, secondary -and minor phases.
After conducting considerable research in this area uie have observed that magnesium oxide present as periclase phase and calcium oxide phase present as lime in refractory materials can be^ selectively dissolved from a matrix of refractory oxides. It has also been found that this dissolution is limited to magensium oxide which is not (chemically combined with oxides of other elements and is further limited to calcium oxide which is not chemically combined with oxides of other elements. This characteristics permits isolation of primary, secondary and minor phases in a number of basic refractory materials by selective extraction of phases.

Accordingly, the present invention provides an improved process for the extraction of alkaline earth oxide phases in ceramic materials, which comprises preparaing an alcoholic solution containing 0.5 to 1.5 wt% water and 0.5 wt% hydroxylamine hydrochloride, mixing powdered ceramic material of size below 52um containing MgO in the range of 35 to 98% and CaO in the range of 0 to 60% to ammonium nitrate solution in such a way that the ratios of ammonium nitrate : alcohol: ceramic material is in the ranges of 12 gms : 200 ml: 5 gms to 20 gms : 300 ml: 5 gms, refluxing the mixture at a temperature range of 60 to 70°C for a period in the range of 10 minutes to 15 hrs., filtering the resultant solution to separate the alkaline earth oxide phases.
In an embodiment of the invention, the alcohol used may be in the form of absolute ethanol, distilled rectified spirit.
The present invention provides an improved method for the isolation of primary, secondary and minor phases from basic refractory materials using organic and inorganic chemicals and apparatus used in chemistry practice. The methods used a salt, ammonium nitrate, which reacts with magnesium and calcium oxide present in the material to be investigated to produce magnesium ammonium nitrate or calcium ammonium nitrate or both as the case may be. The salt, ammonium nitrate, is dissolved in alcohol,

ethyl alcohol, prior to the reaction with the material to be investigated. The invention utilise less number of raw material input over the existing Bogue-Taylor technique for Mgo extraction but at the same time.the efficiency of this new invention is comparable and processes are simple and rapid over the existing methods- For the same, amount of MgO extraction, the total time required in Bogue-Taylor method' is about 135 minutes while it is about 45 minutes for this technique. In the case of CaQ and portlandite extraction in cement materials the new invention requires about 15 minutes whereas the standard ASTM technique requires about 4 hours.
The refractory material is powdered in a suitable manner, such as using a hard agate mortar and pestle, to a sufficiently fine size, such as below 52mm. This powdered material is mixed with the alcoholic solution of ammonium nitrate salt. In the invention, appropriate ratios of the ammonium nitrate salt, the ethyl alcohol solvent and the refractory material were used as given in the examples.The entire mixture is heated under repeated bailing at a temperature" in the range of 60 C to 70 C in apparatus such as a refluxing assembly consisting of a flat bottom short neck glass Erlenmeyer flask with a water coaled glass refluxing condenser. The capacity of the flask and of the condenser may be appropriatly _ chosen, e.g. far 5g. sintered magnesite, 300mL of alcohol, is used, the flask has capacity of at least 500mL and the condenser has a length of at least 300mm.-The flask is heated,using a heating device such as electrical

heating mantle and the heating rate and energy input is controlled using an appropriate device such as an electrical variable resistance energy regulator. The apparatus is de.signed to permit removal of matter at intervals by opening standard tapered ground glass joints which are refitted upon completion of removal. The residual liquid and solid material is filtered through a filtering device, such as a glass funnel lined with a filter paper with the choice of a suitable opening for optimum speed of filtration without loss of solid matter into the separated liquid. The solid residue obtained upon filtration contains the minor/secondary phases while the filtrate contains the major CaO and MgO phases.
It is observed that the rate of dissolution of the major phases like periclase and calcia from the matrix of oxides can be controlled by controlling the time of refluxing, and volume of ethyl alcohol solvent. Additionally, the use of a low amount of water and of hydroxylamine hydrochloride as given in the examples hereunder are used to accelerate the rate of dissolution of periclase phase from the ceramic material. The amount of periclase and calcia phases can be extracted from the various refractory materials are given in the Table I.

Table I
(Table Removed)
The method of dissolving or extracting particular phase or phases from refractory materials has proved to be an excellent method of isolating primary, secondary and minor phases in ceramic materials.
The process of the invention is illustrated by the follwing examples which should not, however, be construed to limit the scope of the invention.
Example 1 5g. sample of natural magnesite from Salem, Tamil Nadu is sintered at 1650 C with one hour soaking in an electrical kiln. The sintered magnesite is powdered to -52mm termed A using an agate mortar and pestles.
20g of dry ammonium nitrateV^R/BRgrade., is dissolved in 300mL of pure ethanol containing less than 0.5*/. water to give a solution termed B. The powder A is added to the solution B and

the mixture is placed in a 500mL Erlenmeyer flask and r«efluxed for 9 hours at 70 C to give a new solution C with the solid residue. This solution C is filtered to separate the residue termed D and the filtrate termed E. It is found that 86 */♦ of MgO present in A is removed in D thereby permitting isolation of secondary phases in D by removing major portion of primary phase periclase in A. Analysing the filtrate E, no presence of elements Ca, Al, Si, Fe and Ti which were present in A were found indicating that only MgO was dissolved from A due to the process indicated in the invention. From phase analysis of powder A and residue D it is apparent that periclase phase has been removed by decrease in MgO reflections (200) and (111) and increase in mont icel .1 i te reflections (131), (130) and (111).
Ex amp le 2 5g. sample of natural magnesite from Salem, Tamil Nadu is sintered at 1650 C with one hour soaking in an electrical kiln.
i
The sintered magnesite is powdered to --52mm termed A using an agate mortar and pestles.
20q of dry ammonium nitrate,'AR/GRgrade, is dissolved in 300mL of pure ethanol containing less than O.5%, water to give a solution termed B. The powder A is added to the solution B and
the mixture is placed in a 500ml Enlenmeyer flask and subjected
o for varying refluxing time at 70 C to give a new solution C with
the solid residue. This solution C is filtered to separate the
residue termed D and the filtrate termed E. It is found that the
dissolution of periclase is controlled by controlling the
refluxing time as shown in the Table II below.

Table II
(Table Removed)
Example- 3 5g. sample of natural magnesite from Salem, Tamil Nadu. is sintered at 1650 C with one hour soaking in an electrical kiln. The sintered magnesite is powdered to ~52u. termed A using an agate mortar and pestles.
20g of dry ammonium nitrate, AR/GRgrade, is dissolved in 300ml_ of pure ethanol containing 1.5% water to give a solution termed B. The powder A is added to the solution B and the mixture is placed in a 500ml_ Erlenmeyer flask and refluxed for 9 hours at 70 C to give a new solution C with the solid residue. This solution C is filtered to separate the residue termed D and the filtrate termed E. It is found that 28 V, of MgD present in A is removed in D in three hours.
Examplef-4 5g. sample of natural magnesite from Salem, Tamil Nadu is sintered at 1650 C with one hour soaking in an electrical kiln.

The sintered magnesite is powdered to -52u termed A Losing an agate mortar and pestles.
20g of dry ammonium nitrate, AR/GRgrade, is dissolved in 300mL of pure ethanol containing 1.5Y. water and 0.5gm hydroxylamine hydrochloride to give a solution termed B. The powder A is added to the solution B and the mixture is placed in a 500mL Erlenmeyer flask and refluxed for 9 hours at 70 C to give a new solution C with the solid residue. This solution C is filtered to separate the residue termed D arid the filtrate termed E. It is found that 68 % of MgO present in A is removed in D in three hours.
Example-5 5g. sample of natural magnesite from Salem, Tamil Nadu is sintered at 1650°C with one hour soaking in an electrical kiln. The sintered magnesite is powdered to -52u termed A using an agate mortar and pestles.
20g of dry ammonium nitrate, AR/GRgrade, is dissolved in SOOmL of pure ethanol containing 0.5% water and 0.5gm of hydroxylamine hydrochloride to give a solution termed B. The powder A is added to the saluti.on B and the mixture is placed in a SOOmL Erlenmeyer flask and refluxed for 9 hours at 70 C to give a new solution C with the solid residue. This solution C is filtered to separate the residue termed D and the filtrate termed E. It is found that 36 */♦ of MgO present in A is removed in D in three hours.

Example-6
5 g sample of dolomite material is sintered to 1650 C. The sintered dolomite material is powdered to -52 u termed F using an agate mortar and pestle.
12g of dry ammonium nitrate, AR/GR grade, is dissolved in 200 mL of pure ethanol containing less than 0.5'/» water to give a solution termed B. The powder F is added to the solution B and the mixture is placed in a 500 mL Erlenmeyer flask and refluxed for 10 minutes at 70 C to give a new solution G with the solid residue. This solution G is filtered to separate the residue termed H and the filtrate termed I. It is found that 60% of CaO present in F is removed in H thereby permitting isolation of primary and secondary phases in H by removing major portion of primary phase lime in F. Analysing the filtrate I, no presence of elements Mg, Al, Si, Fe and Ti which were present in F were found indicating that only CaO was dissolved from F due to the process indicated in the invention. From phase analysis of powder F and residue H it is apparent that lime phase has been removed substantially..
The advantages of the present invention are s
1, a cheaper process than existing techniques due to reduced
raw materials input and manpower.
2. a reduced processing time of,30 to 60% compared to
existing processes through the developed technique.

a process by which uncombined alkaline earth oxides magnesia and calcia are separately leached out from ceramic material which is stbpped so as to provide a material free of calcia or free of calcia and magnesia or intermeadiate stage thereof hitherto not attempted.

We Claim:
1. An improved process for the extraction of alkaline earth oxide phases in ceramic materials, which comprises preparaing an alcoholic solution containing 0.5 to 1.5 wt% water and 0.5 wt% hydroxylamine hydrochloride, mixing powdered ceramic material of size below 52µm containing MgO in the range of 35 to 98% and CaO in the range of 0 to 60% to ammonium nitrate solution in such a way that the ratios of ammonium nitrate : alcohol: ceramic material is in the ranges of 12 gms : 200 ml : 5 gms to 20 gms : 300 ml : 5 gms, refluxing the mixture at a temperature range of 60 to 70°C for a period in the range of 10 minutes to 15 hrs., filtering the resultant solution to separate the alkaline earth oxide phases.
2. An improved process as claimed in claims 1 & 2 wherein the alcohol used is selected from absolute ethanol, distilled rectified spirit.
3. An improved process for the selective extraction of alkaline earth oxide phases in ceramic materials substantially as herein described with reference to the examples.

Documents:

434-del-1995-abstract.pdf

434-del-1995-claims.pdf

434-del-1995-correspondence-others.pdf

434-del-1995-correspondence-po.pdf

434-del-1995-description (complete).pdf

434-del-1995-form-1.pdf

434-del-1995-form-2.pdf

434-del-1995-form-4.pdf

434-del-1995-form-9.pdf

« Previous Patent

Next Patent »

Patent Number

189959

Indian Patent Application Number

434/DEL/1995

PG Journal Number

31/2009

Publication Date

31-Jul-2009

Grant Date

11-Feb-2004

Date of Filing

14-Mar-1995

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001,INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	PERIASWAMY ARJUNAN	C.G.C.R.I, CALCUTTA, W.B.INDIA
2	AMITAV KUMAR	C.G.C.R.I, CALCUTTA, W.B.INDIA
3	MALABIKA CHAUDHURI	C.G.C.R.I, CALCUTTA, W.B.INDIA
4	GAUTAM BANERJEE	C.G.C.R.I, CALCUTTA, W.B.INDIA

PCT International Classification Number

C22B 3/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA