Title of Invention	A PROCESS FOR THE PREPARATION OF LEACHABLE (NON-STOICHIOMETRIC) MANGANESE OXIDE FROM MANGANESE CONTAINING INDUSTRIAL WASTES AND NATURAL PYROLUSITE ORES
Abstract	A process for preparation of leachable (non-stoichiometric) manganese oxide from manganese containing industrial wastes and natural pyrolusite ores which comprises homogenizing powder of manganese containing industrial waste or manganese ore with 10-40 (w/w) low density oil (low density petroleum hydrocarbon) as a liquid state reducing agent, heating the above said resultant mixture in a reactor, at a temperature in the range of 250°-700°C, for a period of 1-4 hours, allowing the reaction mixture to cool down to an ambient temperature, under reducing environment prevailing inside the reactor to obtain the crude reduced manganese oxide, leaching the resultant crude reduced manganese oxide with 10-50% w/v aqueous sulphuric acid, at a temperature of 25-100°C for 1-8 hours to obtain the manganese sulphate, converting the above said manganese sulphate into desired purified non-stoichiometric manganese oxide by known methods.

Title of Invention

A PROCESS FOR THE PREPARATION OF LEACHABLE (NON-STOICHIOMETRIC) MANGANESE OXIDE FROM MANGANESE CONTAINING INDUSTRIAL WASTES AND NATURAL PYROLUSITE ORES

Abstract

A process for preparation of leachable (non-stoichiometric) manganese oxide from manganese containing industrial wastes and natural pyrolusite ores which comprises homogenizing powder of manganese containing industrial waste or manganese ore with 10-40 (w/w) low density oil (low density petroleum hydrocarbon) as a liquid state reducing agent, heating the above said resultant mixture in a reactor, at a temperature in the range of 250°-700°C, for a period of 1-4 hours, allowing the reaction mixture to cool down to an ambient temperature, under reducing environment prevailing inside the reactor to obtain the crude reduced manganese oxide, leaching the resultant crude reduced manganese oxide with 10-50% w/v aqueous sulphuric acid, at a temperature of 25-100°C for 1-8 hours to obtain the manganese sulphate, converting the above said manganese sulphate into desired purified non-stoichiometric manganese oxide by known methods.

Full Text	Field of the invention The present invention relates to a process for the preparation of leachable (non-stoichiometric) manganese oxide from manganese containing industrial wastes and natural pyrolusite ores. Background of the invention The leachable (non-stoichiometric) manganese oxide is used as redox agent and catalyst for many organic reactions, depolarizer in batteries and electrolytic cells. It is substantially leachable in mineral acids and is useful for making many manganese compounds. Reference may be made to the paper of Akdogan and Eric (Minerals Engineering, 7, 5-6, 1994, p. 633 - 645) wherein, reduction of manganese ore has been carried out using carbon and carbon monoxide in the temperature range of 1100-1350 °C. The draw back of this method lies in the use of fairly high temperature of operation leading to higher fuel costs. Welham (Int. J. Miner. Process. 67, 2002, p. 187 - 198) achieved the reduction of manganese bearing ores in the range of 500-700°C by extended milling of the ore with graphite for 10 hours prior to thermal treatment. The drawback of this process lies in the requirement of grinding of ore + graphite mix for 10 hours and thus requiring considerable grinding energy. Kularnani et al. (Indian Pat No. 186399/2001) as well as A.G. Kholmogorov et al. (Hydrometallurgy, 56, 2000, p. 1-11) leached manganese values from manganese ores using sulphuric acid in the presence of pyrite in the temperature range of 80-100 and 70 - 95°C respectively. The works in both these reports suffer from the contamination of the manganese bearing leached solution with considerable quantity of iron present in pyrite. Abou - El - Sherbini (Sep. and Purif. Tech. 27, 2002, 67-75) used sulphur slag for reducing low grade pyrolusite ore at a temperature in the range of 300-400°C in air or in closed stainless steel tube. The drawbacks are the contamination of the reduced mass by iron present in the sulphur slag. Das et al., (Hydrometallurgy, 50 1998, 39 - 49) studied the reaction kinetics of reduction of manganese di-oxide with ammonium sulfite solution by heating in the temperature range of 80-110°C in an autoclave. The procedure suffers from the disadvantage of requiring autoclaving and requirement of ammonium sulfite, a relatively costly chemical. Abbruzzese et al, (Minerals Engineering 3, 1990, p. 307 - 318) achieved maximum leaching of manganese values from low grade manganese ores with aqueous SO2 or through bio-leaching using hetrotrophic micro-organism in 15-20 days operation. This method suffers from the disadvantage of slow reaction kinetics and thus requiring exceedingly large time for leaching. Barner Herbert E et al patented (European Pat No. CA 1050281) a two stage fluid bed process for reduction of manganese ore nodules using synthesis gas to obtain leachable product. The drawback of this process is the requirement of cumbersome two-stage process. Jiei Yangu Uerushiyu et al patented (Pat no. JP 52013414) a method for reducing higher oxide of manganese in manganese ore using solid. This method suffers from insufficient homogenization of the manganese ore with solid reducing agent. Vegman, E.F et al patented a process (Pat No. European RU 2191831) for making manganese values by reduction process using coal carbon as reducing agent. This process suffers from the use of coal carbon, which also leads to insufficient homogenization of the reactants. Welsh Jay Y patented a process for reduction of higher oxide of manganese to leachable manganese using methane rich hydrocarbon gas mixture resulting in the formation of Hydrogen and carbon mono-oxide gas. This process suffers from the use of methane - air mixtures, which require special maintenance. The conventional process of making leachable (non-stoichiometric) manganese oxide from manganese containing materials namely pyrolusite ores etc. involves the use of solid reducing agent which i) limits the homogenization of the reactants and thus requires the relatively higher reduction temperature and reaction time etc. ii) use of solid reducing agents such as coal and iron pyrites etc. contaminates the products with impurities e.g. ash, present in the reducing agents. Objectives of the invention The main object of the present invention is to provide a process for the preparation of leachable (non-stoichiometric) manganese oxide from manganese containing industrial wastes and natural pyrolusite ores which obviates the drawbacks of the hitherto known prior art as detailed above. Yet another object of the present invention is to utilize low density petroleum oil as a novel liquid state reducing agent for making leachable (non-stoichiometric) manganese oxide from manganese containing industrial wastes and natural pyrolusite ores. The use of liquid state low density oil enables through homogenization and a close contact between the two reactant entities. Summary of the invention Accordingly, the present invention provides a process for the preparation of leachable (non-stoichiometric) manganese oxide from manganese containing industrial wastes and natural pyrolusite ores which comprises homogenizing powder of manganese containing industrial waste or manganese ore with 10-40 (w/w) low density oil (low density petroleum hydrocarbon) as a liquid state reducing agent, heating the above said resultant mixture in a reactor, at a temperature in the range of 250 - 700°C, for a period of 1-4 hours, allowing the reaction mixture to cool down to an ambient temperature, under reducing environment prevailing inside the reactor to obtain the crude reduced manganese oxide, leaching the resultant crude reduced manganese oxide with 10-50 % w/v aqueous sulphuric acid, at a temperature of 25- 100°C for 1-8 hours to obtain the manganese sulphate, converting the above said manganese sulphate into desired purified non-stoichiometric manganese oxide by known methods. In an embodiment of the present invention the manganese containing industrial wastes used is an anode mud generated in zinc industries. In yet another embodiment of the present invention the %content of manganese present in the industrial waste used is in the range of 15-50%. In yet another embodiment of the present invention the %content of manganese present in the natural pyrolusite ores used is in the range of 12-50%. In yet another embodiment of the present invention the low density oil used as a liquid state reducing agent is low density petroleum hydrocarbon. In yet another embodiment of the present invention the temperature used for homogenization of mixture of manganese containing materials with low density oil is in range of 500 - 600°C. In yet another embodiment of the present invention the aqueous sulphuric acid used for leaching reduced manganese oxide is in the range of 15 - 25 % w/v aqueous acid. In still another embodiment of the present invention the Mn recovered in the leached acid solution is > 90%. In still another embodiment of the the maximum recovery of manganese is achieved when 30% w/v aqueous sulphuric acid is used as leaching solution. Detail description of the invention Thus the novel process for making leachable (non-stoichiometric) manganese oxide, which is acid leachable, from manganese containing industrial wastes and natural pyrolusite ores comprises of the homogenization of the powder of manganese bearing industrial waste or manganese ore containing 10 to 63 % manganese (as Mn) with 10-40 (w/w) low density oil as a liquid state reducing agent using a Y mixer for 15-30 minutes. The homogenized mix is then placed in a reactor made of mild steel, which is fitted with a tubular outlet with stopper valve to permit the escape of emanating carbon dioxide gas during reduction of manganese bearing industrial waste and ores with low density oil. The reactor is then place in an electric/oil/gas fired furnace and heated in the temperature range of 250-600°C for a duration of one to four hours. At the end of the heating period, the furnace is switched off, the reactors is removed from the furnace and out let valves are closed to maintain the reducing atmosphere inside the reactor. The reactor, containing reduced mass is allowed to cool to ambient temperature, where after the cold reduced mass, containing leachable (non-stoichiometric) manganese oxide is removed from the reactor and is used for leaching in 5-50 % (w/v) sulphuric acid at a temperature ranging from ambient to 100°C for a period ranging from one to 8 hours to obtain desired manganese compounds. The novelty of the present invention with respect to prior art lies in the fact that (i) the novel process of present invention obviates the need of conventionally used reducing agents such as coal (ii) the present process enables through homogenization of industrial waste/manganese ores with liquid state reducing agent viz., low density oil by making use of absorption/adsorption mechanism. The uniform and highly homogenous mixing of ores with liquid reducing agent viz., low density oil enables the reaction to take place at a considerably lower temperature in the range of 240-600°C in a duration of 1 to 4 hours and thus saving considerable energy (iii) the present invention overcomes the problem of contamination of reduced mass with undesirable impurities generated from the use of conventional reducing agents such as pyrites. The following examples are given by way of illustration of the working of the invention in actual practice and therefore should not be construed to limit the scope of the present invention. EXAMPLE- 1. To prepare leachable (non-stoichiometric) manganese oxide, leachable in sulphuric acid from the zinc industry waste, viz., anode mud, 100 g of water washed anode mud (manganese content = 46.6%, as determined by wet chemical analysis method after fusion of the waste with fusion mixture comprising of 5 g Na2CO3 + 5 g K2CO3) was mechanically homogenized with 18 g low density oil for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated at 600°C for two hours in an electrical muffle furnace. After the heat treatment, the reactor contents were cooled to ambient temperature. 5 g of the carbo-thermally reduced mass so obtained was leached with 20% (v/v) aqueous sulphuric acid solution at 100°C for 7 hours followed by cooling to ambient temperature and filtration using Whatman (42 Grade) filter paper. The filtrate was analyzed for its manganese content. The recovery of manganese content in the leached solution was observed to be 93.8% of the total available manganese in the anode mud. EXAMPLE - 2 For preparing leachable (non-stoichiometric) manganese oxide, leachable in sulphuric acid from the zinc industry waste, viz., anode mud, 100 g of anode mud (manganese content = 46.6%, as determined by wet chemical analysis method after fusion of the waste with fusion mixture comprising of 5 g Na2CO3 + 5 g KaCOa) was mechanically homogenized with 18 g low density oil for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated at 500°C for two hours in an electrical muffle furnace. After the heat treatment, the reactor contents were cooled to ambient temperature. 5 g of the carbo-thermally reduced mass so obtained was leached with 30% (v/v) aqeous sulphuric acid solution at 100°C for 7 hours followed by cooling to ambient temperature and filtration using Whatman (42 Grade) filter paper. The filtrate was analysed for its manganese content. The recovery of manganese content in the leached solution was observed to be 80.40% of the total available manganese in the anode mud. EXAMPLE - 3 For preparing leachable (non-stoichiometric) manganese oxide from the zinc industry waste, viz., anode mud, 132 g of anode mud (manganese content = 17.2%) was mechanically homogenized with 32 g low density oil for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated at 600°C for two hours in an electrical muffle furnace. After the heat treatment, the reactor contents were cooled to ambient temperature. 50 g of the carbothermally reduced mass so obtained was leached with 50% (v/v) aqueous sulphuric acid solution at 100°C for 7 hours followed by cooling to ambient temperature and filtration using Whatman (42 Grade) filter paper. The filtrate was analyzed for its manganese content. The recovery of manganese content in the leached solution was observed to be 87% of the total available manganese in the anode mud. EXAMPLE - 4 For preparing leachable (non-stoichiometric) manganese oxide from the zinc industry waste, viz., anode mud, 100 g of this waste (manganese content = 46.6%, as determined by the method of wet chemical analysis of 1 g sample after fusion of the waste with fusion mixture comprising of 5 g NaaCOa + 5 g K2CO3) was mechanically homogenized with 18 g low density oil for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated at 600°C for two hours in an electrical muffle furnace. After the heat treatment, the reactor contents were cooled to ambient temperature. 5 g of the carbo-thermally reduced mass so obtained was leached with 30% (v/v) aqueous sulphuric acid solution at 100°C for 7 hours followed by cooling to ambient temperature and filtration using Whatman (42 Grade) filter paper. The filtrate was analyzed for its manganese content. The recovery of manganese content in the leached solution was observed to be 90.4% of the total available manganese in the anode mud. EXAMPLE - 5 For preparing leachable (non-stoichiometric) manganese oxide from the zinc industry waste, viz., anode mud, 100 g of this waste (manganese content = 46.6%, as determined by the method of wet chemical analysis of 1 g sample after fusion of the waste with fusion mixture comprising of 5 g Na2CO3 + 5 g K2CO3) was mechanically homogenized with 18 g low density oil for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated a 600°C for two hours in an electrical muffle furnace. After the heat treatment, the reactor contents were cooled to ambient temperature. 5 g of the carbo-thermally reduced mass so obtained was leached with 5% (v/v) aqueous sulphuric acid solution at 100°C for 7 hours followed by cooling to ambient temperature and filtration using Whatman (42 Grade) filter paper. The filtrate was analyzed for its manganese content. The recovery of manganese content in the leached solution was observed to be 88.6% of the total available manganese in the anode mud. EXAMPLE - 6 For preparing leachable (non-stoichiometric) manganese oxide from pyrolusite ore, 100 g of the ore (manganese content = 26.95% as determined by the method of wet chemical analysis of 1 g ore sample after fusion with fusion mixture comprising of (5 g Na2CO3 + 5 g K2CO3) was homogenized with 18 g low density oil mechanically for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated at 600°C for two hours in an electrical muffle furnace. After the heat treatment, the reactor contents were cooled to ambient temperature. 50 g of the carbo-themally reduced mass so obtained was leached with 15% (v/v) aqueous sulphuric acid solution at 100°C for 6 hours followed by cooling to ambient temperature and filtration using Whatman (42 Grade) filter paper. The filtrate contains iron as well as manganese. The pH of the solution was raised to 5.5 by addition of NaOH to precipitate out iron content. After filtration, the manganese content in the filtrate was analyzed. The manganese recovery from the ore sample was observed to be 88%. EXAMPLE - 7 For preparing leachable (non-stoichiometric) manganese oxide from pyrolusite ore 96 g of the ore (manganese content = 26.95%, as determined by wet chemical analysis method after fusion of 1 g the ore with fusion mixture comprising of 5 g Na2CO3 + 5 g K2CO3) was homogenized with 10.2 g low density oil mechanically for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated at 700°C for 2 hours in an electrical muffle furnace after the heat treatment, the reactor contents were cooled to ambient temperature. 25 g of the carbo-thermally reduced mass so obtained was leached with 10% (v/v) aqueous sulphuric acid solution at 85°C for one hour followed by cooling to ambient temperature. The pH of the filtrate was adjusted to 5.5 by addition of NaOH to precipitate out iron. After filtration using Whatman (42 Grade) filter paper, the filtrate was analyzed for its manganese content. The recovery of the manganese content in the leached solution was observed to be 83% of the total available manganese in the pyrolusite ore. The main advantages of the present invention are: 1. The novel process of the present invention uses a liquid state reducing agent viz., low density oil which obviates the contamination of leachable (non- stoichiometric) manganese oxide obtained as the reduced mass. 2. The novel process of the present invention uses low density oil which enables a thorough homogenization of the reactants viz., manganese containing industrial wastes and ores with low density oil using absorption/adsorption mechanism. 3. The novel process of the present invention uses low density oil which enables in lowering the reaction temperature substantially. The process is carried out in the temperature range of 240 - 400°C for a duration of only 1-4 hours. 4. The novel process of the present invention utilizes manganese containing industrial wastes and natural ores as resources materials for producing leachable (non-stoichiometric) manganese oxide, suitable for making desired manganese compounds. 5. The leaching of the leachable (non-stoichiometric) manganese oxide is carried out using acids to obtain desired manganese compounds such as manganese sulphate, manganese, chloride, manganese nitrate, manganese phosphate, manganese acetate, manganese oxalate etc. We claim 1. A process for the preparation of leachable (non-stoichiometric) manganese oxide from manganese containing industrial wastes and natural pyrolusite ores which comprises homogenizing powder of manganese containing industrial waste or manganese ore with 10-40 (w/w) low density oil (low density petroleum hydrocarbon) as a liquid state reducing agent, heating the above said resultant mixture in a reactor, at a temperature in the range of 250 - 700°C, for a period of 1-4 hours, allowing the reaction mixture to cool down to an ambient temperature, under reducing environment prevailing inside the reactor to obtain the crude reduced manganese oxide, leaching the resultant crude reduced manganese oxide with 10-50 % w/v aqueous sulphuric acid, at a temperature of 25- 100°C for 1-8 hours to obtain the manganese sulphate, converting the above said manganese sulphate into desired purified non-stoichiometric manganese oxide by known methods. 2. A process as claimed in claim 1, wherein the manganese containing industrial wastes used is an anode mud generated in zinc industries. 3. A process as claimed in claim 1, wherein the %content of manganese present in the industrial waste used is in the range of 10-60%. 4. A process as claimed in claim 1, wherein the %content of manganese present in the natural pyrolusite ores used is in the range of 10-50%. 5. A process as claimed in claim 1, wherein the low density oil used as a liquid state reducing agent is low density petroleum hydrocarbon. 6. A process as claimed in claim 1, wherein the temperature used for homogenization of mixture of manganese containing materials with low density oil is in range of 500 - 600°C. 7. A process as claimed in claim 1, wherein the aqueous sulphuric acid used for leaching reduced manganese oxide is in the range of 15 - 25 % w/v aqueous acid. 8. A process as claimed in claim 1, wherein the Mn recovered in the leached acid solution is > 90%. 9. A process as claimed in claim 1, wherein the maximum recovery of manganese is achieved when 30% w/v aqueous .sulphuric acid is used as leaching solution. 10. A process for the preparation of leachable (non-stoichiometric) manganese oxide from manganese containing industrial wastes and natural pyrolusite ores, substantially as herein described with reference to the examples.

Full Text

Field of the invention
The present invention relates to a process for the preparation of leachable (non-stoichiometric) manganese oxide from manganese containing industrial wastes and natural pyrolusite ores.
Background of the invention
The leachable (non-stoichiometric) manganese oxide is used as redox agent and catalyst for many organic reactions, depolarizer in batteries and electrolytic cells. It is substantially leachable in mineral acids and is useful for making many manganese compounds.
Reference may be made to the paper of Akdogan and Eric (Minerals Engineering, 7, 5-6, 1994, p. 633 - 645) wherein, reduction of manganese ore has been carried out using carbon and carbon monoxide in the temperature range of 1100-1350 °C. The draw back of this method lies in the use of fairly high temperature of operation leading to higher fuel costs. Welham (Int. J. Miner. Process. 67, 2002, p. 187 - 198) achieved the reduction of manganese bearing ores in the range of 500-700°C by extended milling of the ore with graphite for 10 hours prior to thermal treatment. The drawback of this process lies in the requirement of grinding of ore + graphite mix for 10 hours and thus requiring considerable grinding energy.
Kularnani et al. (Indian Pat No. 186399/2001) as well as A.G. Kholmogorov et al. (Hydrometallurgy, 56, 2000, p. 1-11) leached manganese values from manganese ores using sulphuric acid in the presence of pyrite in the temperature range of 80-100 and 70 - 95°C respectively. The works in both these reports suffer from the contamination of the manganese bearing leached solution with considerable quantity of iron present in pyrite. Abou - El - Sherbini (Sep. and Purif. Tech. 27, 2002, 67-75) used sulphur slag for reducing low grade pyrolusite ore at a temperature in the range of 300-400°C in air or in closed stainless steel tube. The drawbacks are the contamination of the reduced mass by iron present in the sulphur slag.
Das et al., (Hydrometallurgy, 50 1998, 39 - 49) studied the reaction kinetics of reduction of manganese di-oxide with ammonium sulfite solution by heating in the temperature range of 80-110°C in an autoclave. The procedure suffers from the disadvantage of requiring autoclaving and requirement of ammonium sulfite, a relatively costly chemical. Abbruzzese et al, (Minerals Engineering 3, 1990, p. 307 -

318) achieved maximum leaching of manganese values from low grade manganese ores with aqueous SO2 or through bio-leaching using hetrotrophic micro-organism in 15-20 days operation. This method suffers from the disadvantage of slow reaction kinetics and thus requiring exceedingly large time for leaching.
Barner Herbert E et al patented (European Pat No. CA 1050281) a two stage fluid bed process for reduction of manganese ore nodules using synthesis gas to obtain leachable product. The drawback of this process is the requirement of cumbersome two-stage process. Jiei Yangu Uerushiyu et al patented (Pat no. JP 52013414) a method for reducing higher oxide of manganese in manganese ore using solid. This method suffers from insufficient homogenization of the manganese ore with solid reducing agent.
Vegman, E.F et al patented a process (Pat No. European RU 2191831) for making manganese values by reduction process using coal carbon as reducing agent. This process suffers from the use of coal carbon, which also leads to insufficient homogenization of the reactants. Welsh Jay Y patented a process for reduction of higher oxide of manganese to leachable manganese using methane rich hydrocarbon gas mixture resulting in the formation of Hydrogen and carbon mono-oxide gas. This process suffers from the use of methane - air mixtures, which require special maintenance.
The conventional process of making leachable (non-stoichiometric) manganese oxide from manganese containing materials namely pyrolusite ores etc. involves the use of solid reducing agent which i) limits the homogenization of the reactants and thus requires the relatively higher reduction temperature and reaction time etc. ii) use of solid reducing agents such as coal and iron pyrites etc. contaminates the products with impurities e.g. ash, present in the reducing agents.
Objectives of the invention
The main object of the present invention is to provide a process for the preparation of leachable (non-stoichiometric) manganese oxide from manganese containing industrial wastes and natural pyrolusite ores which obviates the drawbacks of the hitherto known prior art as detailed above.
Yet another object of the present invention is to utilize low density petroleum oil as a novel liquid state reducing agent for making leachable (non-stoichiometric)

manganese oxide from manganese containing industrial wastes and natural pyrolusite ores. The use of liquid state low density oil enables through homogenization and a close contact between the two reactant entities.
Summary of the invention
Accordingly, the present invention provides a process for the preparation of leachable (non-stoichiometric) manganese oxide from manganese containing industrial wastes and natural pyrolusite ores which comprises homogenizing powder of manganese containing industrial waste or manganese ore with 10-40 (w/w) low density oil (low density petroleum hydrocarbon) as a liquid state reducing agent, heating the above said resultant mixture in a reactor, at a temperature in the range of 250 - 700°C, for a period of 1-4 hours, allowing the reaction mixture to cool down to an ambient temperature, under reducing environment prevailing inside the reactor to obtain the crude reduced manganese oxide, leaching the resultant crude reduced manganese oxide with 10-50 % w/v aqueous sulphuric acid, at a temperature of 25- 100°C for 1-8 hours to obtain the manganese sulphate, converting the above said manganese sulphate into desired purified non-stoichiometric manganese oxide by known methods.
In an embodiment of the present invention the manganese containing industrial wastes used is an anode mud generated in zinc industries.
In yet another embodiment of the present invention the %content of manganese present in the industrial waste used is in the range of 15-50%.
In yet another embodiment of the present invention the %content of manganese present in the natural pyrolusite ores used is in the range of 12-50%.
In yet another embodiment of the present invention the low density oil used as a liquid state reducing agent is low density petroleum hydrocarbon.
In yet another embodiment of the present invention the temperature used for homogenization of mixture of manganese containing materials with low density oil is in range of 500 - 600°C.
In yet another embodiment of the present invention the aqueous sulphuric acid used for leaching reduced manganese oxide is in the range of 15 - 25 % w/v aqueous acid.

In still another embodiment of the present invention the Mn recovered in the leached acid solution is > 90%.
In still another embodiment of the the maximum recovery of manganese is achieved when 30% w/v aqueous sulphuric acid is used as leaching solution.
Detail description of the invention
Thus the novel process for making leachable (non-stoichiometric) manganese oxide, which is acid leachable, from manganese containing industrial wastes and natural pyrolusite ores comprises of the homogenization of the powder of manganese bearing industrial waste or manganese ore containing 10 to 63 % manganese (as Mn) with 10-40 (w/w) low density oil as a liquid state reducing agent using a Y mixer for 15-30 minutes. The homogenized mix is then placed in a reactor made of mild steel, which is fitted with a tubular outlet with stopper valve to permit the escape of emanating carbon dioxide gas during reduction of manganese bearing industrial waste and ores with low density oil. The reactor is then place in an electric/oil/gas fired furnace and heated in the temperature range of 250-600°C for a duration of one to four hours. At the end of the heating period, the furnace is switched off, the reactors is removed from the furnace and out let valves are closed to maintain the reducing atmosphere inside the reactor. The reactor, containing reduced mass is allowed to cool to ambient temperature, where after the cold reduced mass, containing leachable (non-stoichiometric) manganese oxide is removed from the reactor and is used for leaching in 5-50 % (w/v) sulphuric acid at a temperature ranging from ambient to 100°C for a period ranging from one to 8 hours to obtain desired manganese compounds.
The novelty of the present invention with respect to prior art lies in the fact that (i) the novel process of present invention obviates the need of conventionally used reducing agents such as coal (ii) the present process enables through homogenization of industrial waste/manganese ores with liquid state reducing agent viz., low density oil by making use of absorption/adsorption mechanism. The uniform and highly homogenous mixing of ores with liquid reducing agent viz., low density oil enables the reaction to take place at a considerably lower temperature in the range of 240-600°C in a duration of 1 to 4 hours and thus saving considerable energy (iii)

the present invention overcomes the problem of contamination of reduced mass with undesirable impurities generated from the use of conventional reducing agents such as pyrites.
The following examples are given by way of illustration of the working of the invention in actual practice and therefore should not be construed to limit the scope of the present invention.
EXAMPLE- 1.
To prepare leachable (non-stoichiometric) manganese oxide, leachable in sulphuric acid from the zinc industry waste, viz., anode mud, 100 g of water washed anode mud (manganese content = 46.6%, as determined by wet chemical analysis method after fusion of the waste with fusion mixture comprising of 5 g Na2CO3 + 5 g K2CO3) was mechanically homogenized with 18 g low density oil for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated at 600°C for two hours in an electrical muffle furnace. After the heat treatment, the reactor contents were cooled to ambient temperature. 5 g of the carbo-thermally reduced mass so obtained was leached with 20% (v/v) aqueous sulphuric acid solution at 100°C for 7 hours followed by cooling to ambient temperature and filtration using Whatman (42 Grade) filter paper. The filtrate was analyzed for its manganese content. The recovery of manganese content in the leached solution was observed to be 93.8% of the total available manganese in the anode mud. EXAMPLE - 2
For preparing leachable (non-stoichiometric) manganese oxide, leachable in sulphuric acid from the zinc industry waste, viz., anode mud, 100 g of anode mud (manganese content = 46.6%, as determined by wet chemical analysis method after fusion of the waste with fusion mixture comprising of 5 g Na2CO3 + 5 g KaCOa) was mechanically homogenized with 18 g low density oil for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated at 500°C for two hours in an electrical muffle furnace. After the heat treatment, the reactor contents were cooled to ambient temperature. 5 g of the carbo-thermally reduced mass so obtained was leached with 30% (v/v) aqeous

sulphuric acid solution at 100°C for 7 hours followed by cooling to ambient temperature and filtration using Whatman (42 Grade) filter paper. The filtrate was analysed for its manganese content. The recovery of manganese content in the leached solution was observed to be 80.40% of the total available manganese in the anode mud. EXAMPLE - 3
For preparing leachable (non-stoichiometric) manganese oxide from the zinc industry waste, viz., anode mud, 132 g of anode mud (manganese content = 17.2%) was mechanically homogenized with 32 g low density oil for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated at 600°C for two hours in an electrical muffle furnace. After the heat treatment, the reactor contents were cooled to ambient temperature. 50 g of the carbothermally reduced mass so obtained was leached with 50% (v/v) aqueous sulphuric acid solution at 100°C for 7 hours followed by cooling to ambient temperature and filtration using Whatman (42 Grade) filter paper. The filtrate was analyzed for its manganese content. The recovery of manganese content in the leached solution was observed to be 87% of the total available manganese in the anode mud. EXAMPLE - 4
For preparing leachable (non-stoichiometric) manganese oxide from the zinc industry waste, viz., anode mud, 100 g of this waste (manganese content = 46.6%, as determined by the method of wet chemical analysis of 1 g sample after fusion of the waste with fusion mixture comprising of 5 g NaaCOa + 5 g K2CO3) was mechanically homogenized with 18 g low density oil for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated at 600°C for two hours in an electrical muffle furnace. After the heat treatment, the reactor contents were cooled to ambient temperature. 5 g of the carbo-thermally reduced mass so obtained was leached with 30% (v/v) aqueous sulphuric acid solution at 100°C for 7 hours followed by cooling to ambient temperature and filtration using Whatman (42 Grade) filter paper. The filtrate was analyzed for its manganese content. The recovery of manganese content in the leached solution was observed to be 90.4% of the total available manganese in the anode mud.

EXAMPLE - 5
For preparing leachable (non-stoichiometric) manganese oxide from the zinc industry waste, viz., anode mud, 100 g of this waste (manganese content = 46.6%, as determined by the method of wet chemical analysis of 1 g sample after fusion of the waste with fusion mixture comprising of 5 g Na2CO3 + 5 g K2CO3) was mechanically homogenized with 18 g low density oil for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated a 600°C for two hours in an electrical muffle furnace. After the heat treatment, the reactor contents were cooled to ambient temperature. 5 g of the carbo-thermally reduced mass so obtained was leached with 5% (v/v) aqueous sulphuric acid solution at 100°C for 7 hours followed by cooling to ambient temperature and filtration using Whatman (42 Grade) filter paper. The filtrate was analyzed for its manganese content. The recovery of manganese content in the leached solution was observed to be 88.6% of the total available manganese in the anode mud. EXAMPLE - 6
For preparing leachable (non-stoichiometric) manganese oxide from pyrolusite ore, 100 g of the ore (manganese content = 26.95% as determined by the method of wet chemical analysis of 1 g ore sample after fusion with fusion mixture comprising of (5 g Na2CO3 + 5 g K2CO3) was homogenized with 18 g low density oil mechanically for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated at 600°C for two hours in an electrical muffle furnace. After the heat treatment, the reactor contents were cooled to ambient temperature. 50 g of the carbo-themally reduced mass so obtained was leached with 15% (v/v) aqueous sulphuric acid solution at 100°C for 6 hours followed by cooling to ambient temperature and filtration using Whatman (42 Grade) filter paper. The filtrate contains iron as well as manganese. The pH of the solution was raised to 5.5 by addition of NaOH to precipitate out iron content. After filtration, the manganese content in the filtrate was analyzed. The manganese recovery from the ore sample was observed to be 88%. EXAMPLE - 7
For preparing leachable (non-stoichiometric) manganese oxide from pyrolusite ore 96 g of the ore (manganese content = 26.95%, as determined by wet chemical analysis method after fusion of 1 g the ore with fusion mixture comprising

of 5 g Na2CO3 + 5 g K2CO3) was homogenized with 10.2 g low density oil mechanically for a duration of 15 minutes. The homogenized mix so obtained was then placed in a mild steel reactor and heat treated at 700°C for 2 hours in an electrical muffle furnace after the heat treatment, the reactor contents were cooled to ambient temperature. 25 g of the carbo-thermally reduced mass so obtained was leached with 10% (v/v) aqueous sulphuric acid solution at 85°C for one hour followed by cooling to ambient temperature. The pH of the filtrate was adjusted to 5.5 by addition of NaOH to precipitate out iron. After filtration using Whatman (42 Grade) filter paper, the filtrate was analyzed for its manganese content. The recovery of the manganese content in the leached solution was observed to be 83% of the total available manganese in the pyrolusite ore.
The main advantages of the present invention are:
1. The novel process of the present invention uses a liquid state reducing agent
viz., low density oil which obviates the contamination of leachable (non-
stoichiometric) manganese oxide obtained as the reduced mass.
2. The novel process of the present invention uses low density oil which enables
a thorough homogenization of the reactants viz., manganese containing
industrial wastes and ores with low density oil using absorption/adsorption
mechanism.
3. The novel process of the present invention uses low density oil which enables
in lowering the reaction temperature substantially. The process is carried out
in the temperature range of 240 - 400°C for a duration of only 1-4 hours.
4. The novel process of the present invention utilizes manganese containing
industrial wastes and natural ores as resources materials for producing
leachable (non-stoichiometric) manganese oxide, suitable for making desired
manganese compounds.
5. The leaching of the leachable (non-stoichiometric) manganese oxide is
carried out using acids to obtain desired manganese compounds such as
manganese sulphate, manganese, chloride, manganese nitrate, manganese
phosphate, manganese acetate, manganese oxalate etc.

We claim
1. A process for the preparation of leachable (non-stoichiometric) manganese
oxide from manganese containing industrial wastes and natural pyrolusite
ores which comprises homogenizing powder of manganese containing
industrial waste or manganese ore with 10-40 (w/w) low density oil (low
density petroleum hydrocarbon) as a liquid state reducing agent, heating the
above said resultant mixture in a reactor, at a temperature in the range of
250 - 700°C, for a period of 1-4 hours, allowing the reaction mixture to cool
down to an ambient temperature, under reducing environment prevailing
inside the reactor to obtain the crude reduced manganese oxide, leaching
the resultant crude reduced manganese oxide with 10-50 % w/v aqueous
sulphuric acid, at a temperature of 25- 100°C for 1-8 hours to obtain the
manganese sulphate, converting the above said manganese sulphate into
desired purified non-stoichiometric manganese oxide by known methods.
2. A process as claimed in claim 1, wherein the manganese containing
industrial wastes used is an anode mud generated in zinc industries.
3. A process as claimed in claim 1, wherein the %content of manganese
present in the industrial waste used is in the range of 10-60%.
4. A process as claimed in claim 1, wherein the %content of manganese
present in the natural pyrolusite ores used is in the range of 10-50%.
5. A process as claimed in claim 1, wherein the low density oil used as a liquid
state reducing agent is low density petroleum hydrocarbon.
6. A process as claimed in claim 1, wherein the temperature used for
homogenization of mixture of manganese containing materials with low
density oil is in range of 500 - 600°C.
7. A process as claimed in claim 1, wherein the aqueous sulphuric acid used
for leaching reduced manganese oxide is in the range of 15 - 25 % w/v aqueous acid.
8. A process as claimed in claim 1, wherein the Mn recovered in the leached
acid solution is > 90%.
9. A process as claimed in claim 1, wherein the maximum recovery of
manganese is achieved when 30% w/v aqueous .sulphuric acid is used as leaching solution.

10. A process for the preparation of leachable (non-stoichiometric) manganese oxide from manganese containing industrial wastes and natural pyrolusite ores, substantially as herein described with reference to the examples.

Documents:

399-DEL-2006-Abstract-(21-02-2012).pdf

399-del-2006-abstract.pdf

399-del-2006-claims.pdf

399-DEL-2006-Correspondence Others-(21-02-2012).pdf

399-del-2006-correspondence-others 1.pdf

399-del-2006-correspondence-others.pdf

399-del-2006-description(complete).pdf

399-del-2006-form-1.pdf

399-del-2006-form-18.pdf

399-del-2006-form-2.pdf

399-del-2006-form-3.pdf

399-del-2006-form-5.pdf

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Patent Number

254799

Indian Patent Application Number

399/DEL/2006

PG Journal Number

51/2012

Publication Date

21-Dec-2012

Grant Date

19-Dec-2012

Date of Filing

13-Feb-2006

Name of Patentee

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH

Applicant Address

ANUSANDHAN BHAWAN, RAFI MARG, NEW DELHI-110 001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	NAVIN CHANDRA	REGIONAL RESEARCH LABORATORY, HABIB GANJ NAKA, HOSHANGABAD ROAD, BHOPAL-462026 (M.P.) INDIA
2	AMIRTPHALE SUDHIR SITARAM	REGIONAL RESEARCH LABORATORY, HABIB GANJ NAKA, HOSHANGABAD ROAD, BHOPAL-462026 (M.P.) INDIA
3	SRABANTI GHOSH	REGIONAL RESEARCH LABORATORY, HABIB GANJ NAKA, HOSHANGABAD ROAD, BHOPAL-462026 (M.P.) INDIA
4	MURARI PRASAD	REGIONAL RESEARCH LABORATORY, HABIB GANJ NAKA, HOSHANGABAD ROAD, BHOPAL-462026 (M.P.) INDIA
5	DEEPTI SARKAR	REGIONAL RESEARCH LABORATORY, HABIB GANJ NAKA, HOSHANGABAD ROAD, BHOPAL-462026 (M.P.) INDIA

PCT International Classification Number

C10F 5/20

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA