A method for producing battery-grade manganese sesquioxide by using electrolytic manganese anode slime

Abstract

The application discloses a method for producing battery-grade trimanganese tetraoxide by using electrolytic manganese anode slime, and production is carried out according to the following method: (1) electrolytic manganese anode slime is broken and then dried; (2) the electrolytic manganese anode slime is mixed with a flux, and is roasted in a tubular furnace until the reaction is complete; the manganese sulfate is leached out by deionized water at room temperature, and is filtered to obtain leached manganese sulfate crude liquid and leaching residue; (3) a purifying reagent is added to the manganese sulfate crude liquid for purification; (4) ammonium bicarbonate is added to convert the manganese sulfate into manganese carbonate; the manganese carbonate is filtered to obtain manganese carbonate precipitate and ammonium sulfate solution; the manganese carbonate precipitate is calcined to obtain trimanganese tetraoxide; and the trimanganese tetraoxide is crushed, sand-ground, washed and dried to obtain battery-grade trimanganese tetraoxide. The manganese recovery rate can reach more than 99.3%, the energy consumption and cost are lower, and the problems of resource waste and environmental pollution caused by the manganese anode slime of electrolytic manganese manufacturers are solved.

Description

Technical Field

[0001] This invention relates to the field of industrial waste resource utilization, specifically a method for producing battery-grade manganese tetroxide using electrolytic manganese anode mud. Background Technology

[0002] Electrolytic manganese anode slime is formed from manganese carbonate or manganese oxide ore as raw material. After acid leaching and purification, it undergoes an oxygen evolution reaction at the electrolytic manganese anode, resulting in anode slime containing various elements and compounds such as high-valent manganese, lead, silicon, tin, copper, calcium, magnesium, and aluminum. Because it contains 43%-52% manganese, industry typically returns it to the electrolysis system or uses it to produce manganese sulfate or manganese tetroxide. However, since the manganese oxide in electrolytic manganese anode slime is mostly in a colloidal and colloidal ring structure, the traditional wet reduction process has low manganese separation efficiency and high acid leaching wastewater treatment costs. The pyrometallurgical-hydrometallurgical combined process can directly reduce the high-valent manganese in electrolytic manganese anode slime to low-valent (divalent) manganese and leach it directly under neutral conditions, reducing material costs, but with relatively high energy consumption. Currently, domestic manufacturers generally store electrolytic manganese anode slime as hazardous waste, use it as a steelmaking additive, or sell it at a low price as a raw material for ferromanganese and silicomanganese alloy smelting. The degree of development and comprehensive recycling is low, which not only wastes resources but also poses a pollution risk to the environment. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the first objective of this invention is to provide a mixed flux, and the second objective is to provide a method for producing battery-grade manganese tetroxide using electrolytic manganese anode mud, wherein the recovery rate of manganese extracted and recovered from electrolytic manganese anode mud reaches more than 99.3%, and high-purity battery-grade manganese tetroxide is obtained.

[0004] To achieve the first objective mentioned above, the present invention is implemented through the following technical solution: a mixed flux, characterized in that it is composed of 68% ammonium sulfite and 32% urea.

[0005] The second objective of this invention is achieved as follows: a method for producing battery-grade manganese tetroxide using electrolytic manganese anode mud, characterized by the following steps:

[0006] (1) Crush and dry the electrolytic manganese anode mud;

[0007] (2) The dried electrolytic manganese anode mud is mixed with the mixed flux and roasted in a tube furnace until the reaction is complete. Then, the mixture is cooled to room temperature, the roasted residue is removed, and manganese sulfate is leached with deionized water at room temperature. The mixture is filtered to obtain crude manganese sulfate solution and leaching residue.

[0008] (3) Add metallic manganese powder to the crude manganese sulfate solution to remove residual heavy metal impurities, stir and filter to obtain a primary purified solution, add ammonium sulfide to the primary purified solution to further remove heavy metal impurities, filter to obtain a secondary purified solution, add flocculant to the secondary purified solution to remove residual aluminum and silicon, filter to obtain a tertiary purified solution, add ammonia water to the tertiary purified solution to adjust the pH to 6-7, add citric acid to complex with magnesium ions in the solution, filter to obtain a quaternary purified solution.

[0009] (4) Add ammonium bicarbonate to the fourth purification solution to convert manganese sulfate into manganese carbonate. Filter to obtain manganese carbonate precipitate and ammonium sulfate solution. Wash the manganese carbonate precipitate with deionized water and calcine it at 800-900℃ to obtain manganese tetroxide. After crushing, grinding, washing and drying, obtain battery-grade manganese tetroxide.

[0010] In the above scheme: in step (1), the electrolytic manganese anode mud is crushed into particles with a diameter ≤50μm and dried at a temperature of 100-110℃.

[0011] In the above scheme: in step (2), the mass ratio of electrolytic manganese anode mud to mixed flux is 1:1 -1.2.

[0012] In the above scheme, the calcination conditions are as follows: heat up to 200℃ at a heating rate of 5-10℃ / min, calcine at a constant temperature for 110-120min, and then continue to heat up to 620℃ at a heating rate of 5-10℃ / min and hold for 80-90min.

[0013] In the above scheme: in step (2), the amount of deionized water added is 8-12 times the mass of the roasted residue, and the water soaking time is 50-70 min.

[0014] In the above scheme: the flocculant in step (3) is polyacrylamide, the amount added is 1‰-2‰ of the mass of electrolytic manganese anode mud, the amount added of metallic manganese powder is 3‰-5‰ of the mass of electrolytic manganese anode mud, the amount added of ammonium sulfide is 1‰-2‰ of the mass of electrolytic manganese anode mud, and the amount added of ammonium bicarbonate is 0.5%-5% more than the amount of manganese in electrolytic manganese anode mud.

[0015] The ammonium sulfite flux in the mixed flux begins to decompose at low temperatures of 60℃-100℃, initially forming ammonium bisulfite and releasing ammonia gas ((NH4)2SO3→NH4HSO3+NH3). At temperatures of 100℃-200℃, ammonium bisulfite further decomposes into sulfur dioxide and ammonia gas (NH4HSO3→SO2+NH3+H2O). Under this atmosphere, metal oxides in the anode mud, including manganese dioxide, form sulfates, with manganese dioxide primarily reacting to form manganese sulfate ((NH4)2SO3+MnO2→MnSO4+NH3+H2O). However, due to the vigorous decomposition of ammonium sulfite, it readily undergoes a peroxidation side reaction with the metal oxides in the electrolytic manganese anode mud to form manganese oxide ((NH4)2SO3+MnO2→MnO+(NH4)2SO4). To suppress side reactions, this invention incorporates urea and ammonium sulfite as a mixed flux. The addition of urea allows for the slow release of ammonia, inhibiting premature decomposition of ammonium sulfite. Simultaneously, the carbon dioxide produced by the thermal decomposition of urea acts as a protective agent, mitigating the rapid decomposition of ammonium sulfite and thus reducing the formation of side reaction products. For the small amount of manganese oxide generated, due to the formation of ammonium sulfate, the ammonium sulfate decomposes into sulfuric acid and ammonia (220℃-280℃) during subsequent heating, causing the manganese oxide to undergo sulfation to form manganese sulfate. When the temperature rises to 620℃, during this roasting process, all manganese in the electrolytic manganese anode mud is completely converted to manganese sulfate, while some other metal sulfates begin to decompose to form corresponding oxides. In particular, ferric sulfate completely decomposes to form water-insoluble ferric oxide, removing most impurities for subsequent deionized water leaching of manganese sulfate. The manganese sulfate leachate undergoes further impurity removal steps to obtain a high-purity manganese sulfate solution, which is then converted into manganese carbonate and calcined to finally obtain high-purity battery-grade manganese tetroxide.

[0016] Beneficial effects:

[0017] (1) The present invention utilizes the molten salt + water leaching to remove impurities, and the recovery rate of manganese extracted from electrolytic manganese anode mud can reach more than 99.3%.

[0018] (2) Compared with the prior art, the impurity removal is more thorough. The iron content in the product of this invention is much less than 10ppm, which can be used as a raw material for preparing high-end battery cathode materials.

[0019] (3) Lower energy consumption and cost, while solving the problems of resource waste and environmental pollution caused by manganese anode mud from electrolytic manganese manufacturers. Detailed Implementation

[0020] The present invention will be further described below with reference to embodiments.

[0021] Example 1

[0022] The main chemical composition of the electrolytic manganese anode mud sample is as follows: manganese 46.5%, lead 6.8%, iron 2.9%, aluminum 2.6%, calcium 1.3%, magnesium 1.5%, silicon 4.5%, and heavy metals such as zinc, copper, and nickel are in trace amounts. The electrolytic manganese anode mud was crushed and mixed evenly, with a particle size ≤50μm, and then dried to constant weight at 100-110℃.

[0023] Accurately weigh 100g of dried electrolytic manganese anode mud and 100g of mixed flux (68% ammonium sulfite and 32% urea by mass), mix thoroughly, and then perform gradient calcination in a tube furnace. In the tube furnace, heat to 200℃ at a rate of 10℃ / min, hold at that temperature for 120min, then continue heating to 620℃ at a rate of 10℃ / min and hold for 90min. After the reaction is complete, allow the temperature to drop to room temperature, remove the calcined residue sample, add 1L of deionized water to leach manganese sulfate at a constant room temperature, leach for 60min, and then filter to obtain crude manganese sulfate solution. At room temperature, 5‰ (by weight of electrolytic manganese anode mud) of metallic manganese powder was added to the crude manganese sulfate solution to reduce heavy metal ions in the crude solution for 30 minutes. The solution was then separated and filtered to obtain a primary purified manganese sulfate solution. 1‰ (by weight of electrolytic manganese anode mud) of ammonium sulfide was added to the primary purified manganese sulfate solution to further remove heavy metals. The solution was then filtered to obtain a secondary purified manganese sulfate solution. 1‰ (by weight of electrolytic manganese anode mud) of polyacrylamide flocculant was added to remove trace amounts of residual aluminum and silicon from the secondary purified manganese sulfate solution. The solution was stirred for 30 minutes and then filtered to obtain a tertiary purified manganese sulfate solution. Ammonia was added to the tertiary purified manganese sulfate solution to adjust the pH to 6.8. 8g of citric acid was added to complex with magnesium ions in the solution. The solution was then filtered and separated to obtain a quaternary purified manganese sulfate solution. Excess ammonium bicarbonate (5% excess compared to the molar amount of manganese in the electrolytic manganese anode mud) was added to the quaternary purified manganese sulfate solution to react and precipitate manganese carbonate. After the reaction was complete, the solution was filtered to obtain manganese carbonate and ammonium sulfate solutions. The ammonium sulfate solution was evaporated and crystallized for recycling. Manganese carbonate precipitate was washed five times with deionized water and then calcined at 800-900℃ using a suspension low-temperature instantaneous calcination system (calcination system of ZL 201110100752.1) to decompose and obtain solid manganese tetroxide. The solid manganese tetroxide was then crushed or sand-milled, washed with deionized water, and dried to obtain battery-grade manganese tetroxide with a manganese recovery rate of 99.38%.

[0024] Example 2

[0025] The main chemical composition of the electrolytic manganese anode mud sample is as follows: manganese 46.5%, lead 6.8%, iron 2.9%, aluminum 2.6%, calcium 1.3%, magnesium 1.5%, silicon 4.5%, and heavy metals such as zinc, copper, and nickel are in trace amounts. The electrolytic manganese anode mud was crushed and mixed evenly, with a particle size ≤50μm, and then dried to constant weight at 100-110℃.

[0026] Accurately weigh 100g of dried electrolytic manganese anode mud and 120g of mixed flux (68% ammonium sulfite and 32% urea by mass), mix thoroughly, and then perform gradient calcination in a tube furnace. In the tube furnace, heat to 200℃ at a rate of 5℃ / min, hold at that temperature for 110min, then continue heating to 620℃ at a rate of 5℃ / min and hold for 80min. After the reaction is complete, allow the temperature to drop to room temperature, remove the calcined residue sample, add 1.2L of deionized water to leach manganese sulfate at a constant room temperature, leach for 70min, and then filter to obtain crude manganese sulfate solution. At room temperature, 3‰ (by weight of electrolytic manganese anode mud) of metallic manganese powder was added to the crude manganese sulfate solution to reduce heavy metal ions in the crude solution for 30 minutes. The solution was then separated and filtered to obtain a primary purified manganese sulfate solution. 2‰ (by weight of electrolytic manganese anode mud) of ammonium sulfide was added to the primary purified manganese sulfate solution to further remove heavy metals. The solution was then filtered to obtain a secondary purified manganese sulfate solution. 2‰ (by weight of electrolytic manganese anode mud) of polyacrylamide flocculant was added to remove trace amounts of residual aluminum and silicon from the secondary purified manganese sulfate solution. The solution was stirred for 30 minutes and then filtered to obtain a tertiary purified manganese sulfate solution. Ammonia was added to the tertiary purified manganese sulfate solution to adjust the pH to 6. 8g of citric acid was added to complex with magnesium ions in the solution. The solution was then filtered to obtain a quaternary purified manganese sulfate solution. Excess ammonium bicarbonate (0.5% excess compared to the molar amount of manganese in the electrolytic manganese anode mud) was added to the quaternary purified manganese sulfate solution to react and precipitate manganese carbonate. After the reaction was complete, the solution was filtered to obtain manganese carbonate and ammonium sulfate solutions. The ammonium sulfate solution was evaporated and crystallized for recycling. The manganese carbonate precipitate was washed five times with deionized water and then calcined at 800-900℃ using a suspension low-temperature instantaneous calcination system (calcination system of ZL 201110100752.1) to decompose and obtain solid manganese tetroxide. The solid manganese tetroxide was then crushed or sand-milled, washed with deionized water, and dried to obtain battery-grade manganese tetroxide with a manganese recovery rate of 99.3%.

[0027] Example 3

[0028] The main chemical composition of the electrolytic manganese anode mud sample is as follows: manganese 46.5%, lead 6.8%, iron 2.9%, aluminum 2.6%, calcium 1.3%, magnesium 1.5%, silicon 4.5%, and heavy metals such as zinc, copper, and nickel are in trace amounts. The electrolytic manganese anode mud was crushed and mixed evenly, with a particle size ≤50μm, and then dried to constant weight at 100-110℃.

[0029] Accurately weigh 100g of dried electrolytic manganese anode mud and 100g of mixed flux (68% ammonium sulfite and 32% urea by mass), mix thoroughly, and then perform gradient roasting in a tube furnace. In the tube furnace, heat to 200℃ at a rate of 5℃ / min, maintain this temperature for 120min, then continue heating to 620℃ at a rate of 5℃ / min and hold for 90min. After the reaction is complete, allow the temperature to drop to room temperature, remove the roasted residue sample, add 0.8L of deionized water, and leach manganese sulfate at a constant room temperature. After leaching for 50min, filter to obtain crude manganese sulfate solution. The main components of the leaching residue are calcium sulfate and iron oxide. At room temperature, 4‰ (by weight of electrolytic manganese anode mud) of metallic manganese powder was added to the crude manganese sulfate solution to reduce heavy metal ions in the crude solution for 30 minutes. The solution was then separated and filtered to obtain a primary purified manganese sulfate solution. 1‰ (by weight of electrolytic manganese anode mud) of ammonium sulfide was added to the primary purified manganese sulfate solution to further remove heavy metals. The solution was then filtered to obtain a secondary purified manganese sulfate solution. 1‰ (by weight of electrolytic manganese anode mud) of polyacrylamide flocculant was added to remove small amounts of residual aluminum and silicon from the secondary purified manganese sulfate solution. The solution was stirred for 30 minutes and then filtered to obtain a tertiary purified manganese sulfate solution. Ammonia was added to the tertiary purified manganese sulfate solution to adjust the pH to 7. 8g of citric acid was added to complex with magnesium ions in the solution. The solution was then filtered and separated to obtain a quaternary purified manganese sulfate solution. Excess ammonium bicarbonate (3% excess compared to the molar amount of manganese in the electrolytic manganese anode mud) was added to the quaternary purified manganese sulfate solution to react and precipitate manganese carbonate. The precipitate was filtered to obtain manganese carbonate and ammonium sulfate solutions. The ammonium sulfate solution was evaporated and crystallized for recycling. Manganese carbonate precipitate was washed three times with deionized water and then calcined at 800-900℃ using a suspension low-temperature instantaneous calcination system (calcination system of ZL 201110100752.1) to decompose and obtain solid manganese tetroxide. The solid manganese tetroxide was then crushed or sand-milled, washed with deionized water, and dried to obtain battery-grade manganese tetroxide with a manganese recovery rate of 99.35%.

[0030] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for producing battery-grade manganese tetroxide using electrolytic manganese anode mud, characterized in that, Produce according to the following steps: (1) Crush and dry the electrolytic manganese anode mud; (2) The electrolytic manganese anode mud is mixed with a mixed flux, which is composed of 68% ammonium sulfite and 32% urea by mass ratio. The mixture is roasted in a tube furnace until the reaction is complete, then cooled to room temperature, the roasted residue is removed, and manganese sulfate is leached with deionized water at room temperature. The residue is filtered to obtain crude manganese sulfate solution and leaching residue. The mass ratio of electrolytic manganese anode mud to mixed flux is 1:1-1.

2. The roasting conditions are: heating to 200℃ at a heating rate of 5-10℃ / min, roasting at a constant temperature for 110-120 min, and then heating to 620℃ at a heating rate of 5-10℃ / min and holding for 80-90 min. (3) Add metallic manganese powder to the crude manganese sulfate solution to remove residual heavy metal impurities, stir and filter to obtain a primary purified solution, add ammonium sulfide to the primary purified solution to further remove heavy metal impurities, filter to obtain a secondary purified solution, add flocculant to the secondary purified solution to remove residual aluminum and silicon, filter to obtain a tertiary purified solution, add ammonia water to the tertiary purified solution to adjust the pH to 6-7, add citric acid to complex with magnesium ions in the solution, filter to obtain a quaternary purified solution. (4) Add ammonium bicarbonate to the fourth purification solution to convert manganese sulfate into manganese carbonate. Filter to obtain manganese carbonate precipitate and ammonium sulfate solution. Wash the manganese carbonate precipitate with deionized water and calcine it at 800-900℃ to obtain manganese tetroxide. After crushing, grinding, washing and drying, obtain battery-grade manganese tetroxide.

2. The method for producing battery-grade manganese tetroxide using electrolytic manganese anode mud according to claim 1, characterized in that: In step (1), the electrolytic manganese anode mud is crushed into particles with a diameter ≤50 μm and dried at a temperature of 100-110℃.

3. The method for producing battery-grade manganese tetroxide using electrolytic manganese anode mud according to claim 2, characterized in that: In step (2), the amount of deionized water added is 8-12 times the mass of the roasted residue, and the water soaking time is 50-70 min.

4. The method for producing battery-grade manganese tetroxide using electrolytic manganese anode mud according to claim 3, characterized in that: In step (3), the flocculant is polyacrylamide, and the amount added is 1‰-2‰ of the mass of electrolytic manganese anode mud. The amount added is 3‰-5‰ of the mass of electrolytic manganese anode mud. The amount added is 1‰-2‰ of the mass of electrolytic manganese anode mud. The amount added is 0.5%-5% excess of the molar amount of manganese in the electrolytic manganese anode mud.