Title of Invention

"AN IMPROVED PROCESS FOR RECOVERY OF MANGANESE FROM MANGANESE DIOXIDE ORE"

Abstract

This invention relates to an improved process for the recovery of manganese from manganese ore. In the process waste SO2 gas can be used in place of aqueous SO2 or commercial grade SO2 available in the market as reagent for leaching Mn from low grade Mn ore. The Mn is extracted from the low grade ore which do not find use for any purpose.The leaching can be carried out in room temperature and atmosphere pressure which keeps the process as simple as possible and does not require any sophisticated equipment. Manganese sulphate soluttion of high concentration (125 gpl Mn) can be prepared by SO2 gas leaching which reduces the volume of leach liquor to be treated in down-stream processing. The manganese ore contains 51.43% MnO2 and 1.90% P2O5 by SO2 leaching.

Full Text

This invention relates to an improved process for the recovery of manganese from manganese ore. More particularly this invention relates to an improved process for the extraction of manganese from manganese ore. Manganese can be extracted from its dioxide ores either by reduction roasting followed by acid leaching or by aqueous reduction using various reducing agents. The former involves high temperature phenomena whereas the later can be carried out at room temperature and atmospheric pressure. Reagents which can act as potential reducing agent in aqueous media are SO2. FeSO4. FeCl2, sucrose etc. Reaction of SO2 with manganese oxide ore is faster than any other reagent. Manganese ore deposit of Raygada district of Orissa estimates about 6 million tonnes with -30% manganese. Presence of high iron, phosphorus and silica in most of the ore makes them unsuitable for industrial purposes. These ores can be made useful by developing suitable hydrometallurgical process to prepare different manganese compounds. One attractive way to utilise these manganese ore is to dissolve the manganese as soluble sulphate, purify and use them either as to produce manganese metal or batten grade manganese oxide or manganese sulphate monohydrate. India imports battery grade manganese ore to blend with domestic ore and make them suitable for battery manufacture. Preparation of synthetic batten' grade manganese dioxide at reasonable cost will stop import and save foreign exchange. Manganese (It) sulphate monohydrate has got specific use in textile printing, glass working, raw material for producing other high pure Mn-chemicals etc. The attractiveness of use of SO2 is due to the fact that it is one of the major constituents of gaseous emissions from sulphide smelting plant and industries using fossil fuels. SO2 can no longer be vented into the atmosphere because of severe anti-pollution law. Use of this hazardous gas for extraction of manganese will have an added advantage from the environmental point of view. Use of SO2 is also encouraged by its rapid rate of reaction, ambient temperature and atmospheric pressure operation, ease of purifying leach liquors and elimination of barren solution disposal problem. A number of processes have been developed to extract manganese from this ore with SO2. During the First World War. the US Bureau of Mines developed the Lever process which involved counter-current leaching of slurried ore in drums with off-gas containing SO2. Then during Second World War. the Hanna Company built a small commercial plant (1000 td"1) where the ground ore was circulated counter currently with an air-SO2 mixture in packed towers. To overcome the difficulties that were encountered with these processes, the Chemical Construction Corporation developed a further variant, the chemical process. US Bureau of Mines have conducted a series of trials on heap and vat leaching of various manganese ores using SO2 solutions. A process is also developed for percolation leaching of Italian manganese ore (C. Abbruzzese : Hydrometallurgy. 25. 199u. 85-97). In this process. 94.4% of manganese can be recovered in 20 days. The leachate contains only 28.5 gpl manganese. More than 95% of manganese could be extracted within 10 minutes from Greek manganese ore by SO2 leaching (D. Grimenelis, P. Neou-Syngouna and H. Vazarlis: Hydrometallurgy, 31, 1992, 139-146). The novelty of the process are : 1. The waste SO2 gas can be used in place of aqueous SO2 or commercial grade SO2 available in the market as reagent for leaching Mn from low grade Mn ore. 2. The Mn is extracted from the low grade ore which do not find use for any purpose. 3. The leaching can be carried out in room temperature and atmospheric pressure which keeps the process as simple as possible and does not require any sophisticated equipment. 4. Manganese sulphate solution of high concentration (125 gpl Mn) can be prepared by SO2 gas leaching which reduces the volume of leach liquor to be treated in down-stream processing. 5. Iron content in the leach liquor is less. The objective of the present inventions is to provide an improved process for extraction of manganese from manganese ore which contains 51.43% MnCO2 and 1.90% P2O5 by SO2 leaching. Accordingly the present invention provides an improved process for recovery of manganese from manganese ore which comprises; grinding of the ore to 150 micron size, adding aqueous SO2 of 3.5% concentration to the ground ore for aqueous leaching or passing SO2 gas through a manganese ore slurry of 50 wt% pulp density and agitating the slurry by conventional methods at temperature in the range of 25-85°C for 20-90 minutes at atmospheric pressure, filtering & recovering the manganese by known methods. In the preferred embodiment of the inventions the medium used for leaching may be selected from commercial grade aqueous SO2 for aqueous leaching or SO2 gas available in the market for SO2 gas leaching. In another embodiment the medium used for dilution or preparation of slurry should be water. In another embodiment the manganese ore used may have the composition of 51.43% MnO2, 23.59% Fe2O3,1.02% K20,4.56% A12O3, 0.19% BaO, and 1.90% P20s acid insoluble. In yet another embodiment of the manganese ore employed has the size of -150 micron. Manganese ore is leached with SO2 to produce manganese sulphate solution. The solution may be processed for preparation of manganese sulphate/synthetic MnO2/Mn metal. Aqueous SO2 leaching The SO2 solution provided by MERCK, India was used. Its concentration was estimated to be 3.5%. For each experiment a glass reactor was changed with manganese ore and the reaction was initiated by adding aqueous SO2 solution. The slurry was agitated continuously with a mechanical stirrer to keep all the particles in suspension. Stirring speed was measured by means of a digital tachometer. The mouth of reactor was open to atmosphere. The process of the present invention are illustrated by the Examples given below which should not, however, be construed to limit the scope of the present inventions. SO2 gas leaching In order to increase the concentration of manganese in the leachate. Experiments were carried out with higher pulp density. SO2 cylinder was procured from market. Manganese ore slurry of 50% pulp density was prepared adding water. The slurry was transferred into a glass reactor and agitated by a mechanical stirrer to keep all the particles in suspension. SO2 gas was tapped from the cylinder and bubbled through the slurry. The mouth of the reactor was open to atmosphere. Example -1 100 g of-150 micron manganese ore having 51.43% MnO2, 23.59% Fe2O3, 1.02% K20, 4.56% A12O3, 0.19% BaO, 1.90% and 8.62% acid insoluble was poured into glass reactor. 2.14 liters of solution with SO2 concentration 3.5% was added to the ore. The pulp density and stirring speed was 4.67% wt.% and 1000 min"1 respectively. Leaching was carried out at room temperature (~29°C) and atmospheric pressure for 30 minutes. The slurry was filtered using filter paper to separate leachate from residue. Concentration of manganese and iron in the leachate was analysed by atomic absorption spectrophotometer. The leachate contained 18.4 gpl manganese and 0.34 gpl iron. The extraction of manganese and iron was 96.19% and 3.46% respectively. Example - 2 500 g of-150 micron manganese ore having 51.43% MnO2,23.59% Fe203,1.02% K20,4.56% A12O3) 0.19% BaO, 1.90% P2O5 and 8.62% acid insoluble was poured into glass reactor. 10.7 liters of solution with SO2 concentration 3.5% was added to the ore. The pulp density and stirring speed was 4.67 wt.% and 2500 min"1 respectively. Leaching was carried out at room temperature (-29°C) and atmospheric pressure for 30 minutes. The slurry was filtered using filter paper to separate leachate from residue. Concentration of manganese and iron in the leachate was analysed by atomic absorptionspectrophotometer. The leachate contained 16.9 gpl manganese and 0.28 gpl iron. The extraction of manganese and iron was 95.45% and 3.09% respectively. Example - 3 100 g of-150 micron manganese ore having 51.43% MnO2, 23.59% Fe2O3,1.02% K2O, 4.56% A12O3, 0.19% BaO, 1.90% and 8.62% acid insoluble was poured into glass reactor. 200 ml of water was added to the ore to make a slurry of 50 wt.% pulp density. The stirring speed was 500 min"1. SO2 gas was bubbled through the slurry at the rate of 150 cc per minute. Leaching was carried out in room temperature and atmospheric pressure. The temperature of the slurry gradually increased and reached its peak 75°C within 80 minutes. Total duration of leaching was 2 hours. The slurry was filtered using filter paper to separate leachate from residue. The leachate contained 125 gpl manganese and 3.26 gpl iron. The extraction of manganese and iron was 93.82% and 3.77% respectively. Example - 4 500 g of 150 micron manganese ore having 51.43% MnO2, 23.59% Fe2O3, 1.02% K20,4.56% A12O3, 0.19% BaO, 1.90% P2O5 and 8.62% acid insoluble was poured into glass reactor. 1000 ml of water was added to the ore to make a slurry of 50 wt.% pulp density. The stirring speed was 1000 min"1. SO2 gas was bubbled through the slurry at the rate of 2 liter/minute. Leaching was carried out at room temperature and atmospheric pressure. The temperature of the slurry gradually increased and reached its peak 85°C within 25 minutes. Total duration of leaching was 1 hour. The slurry was filtered using filter paper to separate leachate from residue. The leachate contained 123 gpl manganese and 3.25 gpl iron. The extraction of manganese and iron was 93.51% and 3.69% respectively. We Claim: 1. An improved process for recovery of manganese from manganese ore which comprises; grinding of the ore to 150 micron size, adding aqueous SO2 of 3.5% concentration to the ground ore for aqueous leaching or passing SO2 gas through a manganese ore slurry of 50 wt% pulp density and agitating the slurry by conventional methods at temperature in the range of 25-85°C for 20-90 minutes at atmospheric pressure, filtering & recovering the manganese by known methods. 2. An improved process as claimed in claim 1 wherein manganese ore has the composition 51.43% MnO2, 23.59% Fe2O3, 1.02% K2O, 4.56% A12O3, 0.19% BaO, 1.90%, P2O5 & 8.62% insoluble. 3. An improved process for recovery of manganese from manganese ore substantially as herein described with reference to examples.

Documents:

809-del-2001-abstract.pdf

809-del-2001-claims.pdf

809-del-2001-correspondence-others.pdf

809-del-2001-correspondence-po.pdf

809-del-2001-description (complete).pdf

809-del-2001-form-1.pdf

809-del-2001-form-18.pdf

809-del-2001-form-2.pdf

809-del-2001-form-3.pdf