Method for extracting and producing battery-grade manganese sulfate

Abstract

The invention provides a method for extracting and producing battery-grade manganese sulfate, which comprises the following steps: by taking ferrous sulfate as a reducing agent, leaching low-grade manganese oxide ore by using a sulfuric acid solution, then removing iron ions and heavy metal ions through barium sulfide precipitation, and finally extracting by using alpha-hydroxyalkylphosphinic acid to extract manganese sulfate into an organic phase and magnesium, zinc and the like into a water phase, thereby obtaining the battery-grade manganese sulfate. Therefore, the effect of improving the purity of manganese sulfate is achieved, and finally high-purity manganese sulfate is prepared. According to the method, after the manganese ore is reduced and leached by adopting the leached ferrous sulfate, iron ion impurities are removed by adopting barium sulfide precipitation, and impurities such as magnesium and zinc are further removed through extraction, so that the purity of the manganese sulfate in an organic phase is greatly improved, and a technical direction is provided for producing the high-purity manganese sulfate.

Description

Technical Field

[0001] The invention belongs to the technical field of manganese ore extraction, and particularly relates to a method for extracting and producing battery-grade manganese sulfate. Background Art

[0002] my country is a major producer and consumer of manganese products in the world, and is the largest producer and consumer of manganese products such as electrolytic manganese, ferromanganese alloy, silicon-manganese alloy, manganese sulfate and electrolytic manganese dioxide. The output of manganese sulfate in my country has been rising slowly year after year, while the output of high-purity manganese sulfate has risen sharply, doubling from 2018 to 2020. The proportion of high-purity manganese sulfate output in manganese sulfate output has also been increasing. The main reason is the rapid development of the new energy electric vehicle industry in recent years. As a precursor of ternary cathode materials for electric vehicle batteries, the demand for high-purity manganese sulfate is increasing, and high-purity manganese sulfate will inevitably become one of the main manganese products for major manufacturers to compete.

[0003] Metallic manganese is an indispensable raw material to support the development of emerging industries such as new energy and new materials, and its application involves many aspects of the national economy. With the booming global new energy vehicle industry, the market for high-purity manganese sulfate, which is a precursor of positive electrode materials for electric vehicle batteries, is also expanding, and the demand for high-purity manganese sulfate will also increase. Therefore, the production process of high-purity manganese sulfate is also in urgent need of improvement. However, in the production process of electrolytic manganese, various impurities in the manganese sulfate solution are difficult to remove, which will cause problems such as reduced quality of downstream products, increased production costs, and difficulty in recycling manganese. Therefore, achieving effective separation of impurities in manganese sulfate production is an important issue that needs to be solved in the preparation of high-purity manganese sulfate in the manganese metallurgical industry. Summary of the invention

[0004] Aiming at the disadvantage of low impurity removal rate in the existing high-purity manganese sulfate preparation process, the present invention provides a method for extracting and producing battery-grade manganese sulfate, which uses a solvent extraction method to simultaneously separate calcium, magnesium, potassium and sodium impurities while removing iron ions and heavy metals from the leachate, and optimizes the extraction process to prepare high-purity manganese sulfate.

[0005] The present invention is achieved through the following technical solutions: A method for extracting and producing battery-grade manganese sulfate comprises the following steps: S1: Take manganese ore, add ferrous sulfate reducing agent, then add sulfuric acid and water to mix, stir evenly at a speed of 100-150r / min in a water bath at 70-90°C, react for 30-50min, filter the mixed solution, and obtain a leachate; The amount of ferrous sulfate added is 1.6-2.4 g / g manganese ore, the amount of sulfuric acid solution added is 0.7-1.0 g / g manganese ore, and the solid-liquid ratio is 6-12 mL / g; S2: Add 1.8 to 2.1 times the mass of barium sulfide crystals to the leaching solution, stir evenly in a constant temperature water bath at 70 to 90°C and react for 40 to 80 minutes, then stand for 4 to 5 hours, filter and obtain a purified solution; S3: Take α-hydroxy-2-ethylhexylphosphinic acid, dissolve it in kerosene to prepare an extractant with a concentration of 150-250 g / L, then add a sodium hydroxide solution with a mass fraction of 30-40% for saponification, and stand to separate the phases until the organic phase: aqueous phase is (1-3): 1, to obtain a sodium soap extractant; S4: Mix the purified liquid with a sodium soap extractant, extract at 25-30° C. for 10-15 minutes, then allow to stand for phase separation, remove the lower aqueous phase and filter to obtain a manganese sulfate solution.

[0006] The invention uses ferrous sulfate as a reducing agent, uses a sulfuric acid solution to leach low-grade manganese oxide ore, then removes heavy metal ions through barium sulfide precipitation, and finally uses alpha-hydroxyalkylphosphinic acid for extraction, extracts manganese sulfate into an organic phase, and extracts magnesium, zinc, etc. into an aqueous phase, thereby achieving the effect of improving the purity of manganese sulfate, and finally preparing high-purity manganese sulfate.

[0007] When ferrous sulfate is used as a reducing agent, the liquid-solid ratio can increase the manganese leaching rate to a certain extent. When the liquid-solid ratio is low, the slurry viscosity is large and filtration is difficult. When the liquid-solid ratio is high, the manganese concentration of the leachate is low. Considering comprehensively, the liquid-solid ratio is selected to be 6-12mL / g manganese ore, at which time the manganese ion concentration of the leachate is the highest. With the increase of sulfuric acid dosage, manganese leaching first increases sharply, and then increases slowly. Excessive sulfuric acid dosage will cause acid waste, and the acidity of the leachate is high, and subsequent neutralization treatment will consume a lot of alkali. Considering comprehensively, the sulfuric acid dosage is selected to be 0.7-1.0g / g manganese ore.

[0008] The amount of barium sulfide affects the precipitation of manganese and iron. The iron precipitation rate increases sharply and linearly with the increase of barium sulfide dosage, while the manganese precipitation rate increases at a lower rate, that is, most of the added barium sulfide is used to precipitate Fe 2+ ; When the amount of barium sulfide reaches a certain amount, the iron is completely precipitated and removed. At this time, continuing to increase the amount of barium sulfide will cause the manganese precipitation rate to rise sharply. In order to make the amount of manganese precipitation small and the amount of iron precipitation large, the amount of barium sulfide is determined to be 1.8 to 2.1 times the leaching solution. As the precipitation temperature increases, the iron precipitation rate gradually increases, and the manganese precipitation rate gradually decreases. The precipitation reaction is an exothermic reaction. As the temperature increases, the precipitation reaction equilibrium moves toward the dissociation direction. At this time, the MnS precipitation equilibrium moves toward the dissociation direction, and the dissociated S 2- and Fe 2+ The reaction generates extremely insoluble FeS precipitate, which leads to an increase in the iron precipitation rate. In order to reduce the volatilization of the solution, the reaction temperature is selected to be 70-90°C.

[0009] During extraction, as the ratio of the organic phase to the aqueous phase increases, the amount of the organic phase increases relative to the aqueous phase, that is, the amount of the extractant increases relative to the manganese and magnesium ions to be extracted, and the extraction rate increases. When α-hydroxy-2-ethylhexylphosphinic acid is used as the extractant, the difference in the extraction rate of manganese and magnesium ions is relatively obvious, and at the same time, the distribution ratio of manganese and magnesium is also significantly different. Manganese is more likely to enter the organic phase, and magnesium is more likely to remain in the aqueous phase, thereby achieving the separation of manganese and magnesium. When the concentration of α-hydroxy-2-ethylhexylphosphinic acid is controlled at 150-250g / L, the distribution ratio of magnesium is very small and is easy to remain in the aqueous phase, and the distribution ratio of manganese is very large and is easy to transfer from the aqueous phase to the organic phase, thereby achieving the maximum extraction rate of both, thereby improving the purity of manganese sulfate in the organic phase.

[0010] As a further improvement of the present invention, the preparation method of the α-hydroxyalkylphosphinic acid is as follows: A1: Heptanal and a 50% by mass hypophosphorous acid aqueous solution are mixed in a molar ratio of (1.2-1.5):1, 1,4-dioxane is added as an organic solvent, and the mixture is heated to condense and reflux in the presence of concentrated hydrochloric acid at a temperature of 70-90° C. and a reaction time of 3-5 h to obtain a mixture; A2: Cool the mixture to room temperature, add 7% sodium hydroxide aqueous solution until the pH of the aqueous phase is greater than 10, separate the liquids and retain the aqueous phase; A3: Add 10% hydrochloric acid solution to the aqueous phase until the pH is less than 3, add an appropriate amount of ethyl acetate to extract three times, and retain the organic phase; A4: The organic phase was washed three times with saturated brine, dried over anhydrous sodium sulfate, and rotary evaporated at 55° C. to obtain α-hydroxy-2-ethylhexylphosphinic acid.

[0011] As a further improvement of the present invention, in step S3, sulfuric acid is used to adjust the pH of the aqueous phase to 3-5.

[0012] As the pH value of the aqueous phase increases, the degree of ionization of the extractant increases, making it easier to form a stable complex with metal ions, increasing the extraction rate of the extractant for metal ions. Under conditions of strong acidity in the aqueous phase, protonation will inhibit the dissociation of the acidic extractant and reduce the extraction rate of metal ions. If the pH value of the solution is too high, the Mn in the aqueous phase will 2+ It will precipitate out, which is not conducive to extraction. Therefore, when the pH of the aqueous phase is controlled at 3-5, the optimal extraction rate of manganese, magnesium and zinc can be achieved.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention adopts ferrous sulfate reduction to leach manganese ore, and then adopts barium sulfide precipitation to remove iron ion impurities, and then further removes impurities such as magnesium and zinc by extraction, so that the purity of manganese sulfate in the organic phase is greatly improved, which provides a technical direction for the production of high-purity manganese sulfate.

[0014] 2. The α-hydroxy-2-ethylhexylphosphinic acid prepared by the present invention has good extraction performance for manganese, magnesium, zinc, etc., and can be returned to the electrolyte after extraction for electrolytic manganese production. The regenerated organic phase can be returned to the extraction process for recycling. Ammonium bicarbonate and ammonia water are added to the raffinate, and the magnesium oxide product is obtained by stirring, heating, heat preservation, filtering and roasting. DETAILED DESCRIPTION

[0015] The present invention is further described below with reference to the embodiments. In the embodiments, unless otherwise specified, the technical means used are all conventional technical means in the art. Example 1

[0016] A method for extracting and producing battery-grade manganese sulfate comprises the following steps: S1: Take manganese ore, add ferrous sulfate reducing agent, then add sulfuric acid and water to mix, stir evenly at a speed of 100r / min in a 70°C water bath, react for 50min, filter the mixed solution to obtain a leachate; The amount of ferrous sulfate added is 1.6 g / g manganese ore, the amount of sulfuric acid solution added is 0.7 g / g manganese ore, and the solid-liquid ratio is 6 mL / g; S2: Add 1.8 times the mass of barium sulfide crystals to the leaching solution, stir evenly in a 70°C constant temperature water bath and react for 40 minutes, then stand for 4-5 hours and filter to obtain a purified solution; S3: Take α-hydroxy-2-ethylhexylphosphinic acid, dissolve it in kerosene to prepare an extractant with a concentration of 250 g / L, then add a 30% mass fraction sodium hydroxide solution for saponification, stand and separate the phases until the organic phase: aqueous phase is 1:1, and obtain a sodium soap extractant; adjust the pH of the aqueous phase to 3 with sulfuric acid; S4: The purified liquid is mixed with a sodium soap extractant, and the mixture is extracted at 25° C. for 10 min. The mixture is then allowed to stand for phase separation, and the lower aqueous phase is taken out for suction filtration to obtain a manganese sulfate solution.

[0017] The preparation method of the α-hydroxyalkylphosphinic acid is as follows: A1: Heptanal and a 50% by mass aqueous solution of hypophosphorous acid are mixed at a molar ratio of 1.2:1, 1,4-dioxane is added as an organic solvent, and the mixture is heated to condense and reflux in the presence of concentrated hydrochloric acid at a heating temperature of 70° C. and a reaction time of 3 h to obtain a mixture; A2: Cool the mixture to room temperature, add 7% sodium hydroxide aqueous solution until the pH of the aqueous phase is greater than 10, separate the liquids and retain the aqueous phase; A3: Add 10% hydrochloric acid solution to the aqueous phase until the pH is less than 3, add an appropriate amount of ethyl acetate to extract three times, and retain the organic phase; A4: The organic phase was washed three times with saturated brine, dried over anhydrous sodium sulfate, and rotary evaporated at 55° C. to obtain α-hydroxy-2-ethylhexylphosphinic acid.

[0018] The organic phase manganese sulfate extraction rate of this embodiment is 99.84%, the magnesium extraction rate in the aqueous phase is 11.21%, and the zinc extraction rate is 10.28%. Example 2

[0019] A method for extracting and producing battery-grade manganese sulfate comprises the following steps: S1: Take manganese ore, add ferrous sulfate reducing agent, then add sulfuric acid and water to mix, stir evenly at a speed of 150r / min in a 70°C water bath, react for 70min, filter the mixed solution to obtain a leachate; The amount of ferrous sulfate added is 2.4 g / g manganese ore, the amount of sulfuric acid solution added is 1.0 g / g manganese ore, and the solid-liquid ratio is 12 mL / g; S2: Add 1.8 times the mass of barium sulfide crystals to the leaching solution, stir evenly in a constant temperature water bath at 70°C and react for 40 minutes, then let stand for 4 hours, filter and obtain a purified solution; S3: Take α-hydroxy-2-ethylhexylphosphinic acid, dissolve it in kerosene to prepare an extractant with a concentration of 150 g / L, then add a 30% mass fraction sodium hydroxide solution for saponification, stand and separate the phases until the organic phase: aqueous phase is 3:1, and obtain a sodium soap extractant; adjust the pH of the aqueous phase to 5 with sulfuric acid; S4: The purified liquid is mixed with a sodium soap extractant, and the mixture is extracted at 30° C. for 15 minutes, and then allowed to stand for phase separation, and the lower aqueous phase is taken out for suction filtration to obtain a manganese sulfate solution.

[0020] The preparation method of the α-hydroxyalkylphosphinic acid is as follows: A1: Heptanal and a 50% by mass aqueous solution of hypophosphorous acid are mixed at a molar ratio of 1.5:1, 1,4-dioxane is added as an organic solvent, and the mixture is heated to reflux under condensation in the presence of concentrated hydrochloric acid at a heating temperature of 90° C. and a reaction time of 5 h to obtain a mixture; A2: Cool the mixture to room temperature, add 7% sodium hydroxide aqueous solution until the pH of the aqueous phase is greater than 10, separate the liquids and retain the aqueous phase; A3: Add 10% hydrochloric acid solution to the aqueous phase until the pH is less than 3, add an appropriate amount of ethyl acetate to extract three times, and retain the organic phase; A4: The organic phase was washed three times with saturated brine, dried over anhydrous sodium sulfate, and rotary evaporated at 55° C. to obtain α-hydroxy-2-ethylhexylphosphinic acid.

[0021] The organic phase manganese sulfate extraction rate of this embodiment is 99.96%, the magnesium extraction rate in the aqueous phase is 10.28%, and the zinc extraction rate is 11.08%. Example 3

[0022] A method for extracting and producing battery-grade manganese sulfate comprises the following steps: S1: Take manganese ore, add ferrous sulfate reducing agent, then add sulfuric acid and water to mix, stir evenly at a speed of 120r / min in a water bath at 80°C, react for 40min, filter the mixed solution to obtain a leachate; The amount of ferrous sulfate added is 2.0 g / g manganese ore, the amount of sulfuric acid solution added is 0.8 g / g manganese ore, and the solid-liquid ratio is 8 mL / g; S2: Add 2.0 times the mass of barium sulfide crystals to the leaching solution, stir evenly in a constant temperature water bath at 80°C and react for 50 minutes, then stand for 4 hours and filter to obtain a purified solution; S3: Take α-hydroxy-2-ethylhexylphosphinic acid, dissolve it in kerosene to prepare an extractant with a concentration of 200 g / L, then add a sodium hydroxide solution with a mass fraction of 30-40% for saponification, stand and separate the phases until the organic phase: aqueous phase is 2:1, and obtain a sodium soap extractant; adjust the pH of the aqueous phase to 4 with sulfuric acid; S4: The purified liquid is mixed with a sodium soap extractant, and the mixture is extracted at 26° C. for 12 minutes, and then allowed to stand for phase separation, and the lower aqueous phase is taken out for suction filtration to obtain a manganese sulfate solution.

[0023] The preparation method of the α-hydroxyalkylphosphinic acid is as follows: A1: Heptanal and a 50% by mass aqueous solution of hypophosphorous acid are mixed at a molar ratio of 1.3:1, 1,4-dioxane is added as an organic solvent, and the mixture is heated to condense and reflux in the presence of concentrated hydrochloric acid at a heating temperature of 80° C. and a reaction time of 4 h to obtain a mixture; A2: Cool the mixture to room temperature, add 7% sodium hydroxide aqueous solution until the pH of the aqueous phase is greater than 10, separate the liquids and retain the aqueous phase; A3: Add 10% hydrochloric acid solution to the aqueous phase until the pH is less than 3, add an appropriate amount of ethyl acetate to extract three times, and retain the organic phase; A4: The organic phase was washed three times with saturated brine, dried over anhydrous sodium sulfate, and rotary evaporated at 55° C. to obtain α-hydroxy-2-ethylhexylphosphinic acid.

[0024] The organic phase manganese sulfate extraction rate of this embodiment is 97.86%, the magnesium extraction rate in the aqueous phase is 12.16%, and the zinc extraction rate is 10.66%. Example 4

[0025] A method for extracting and producing battery-grade manganese sulfate comprises the following steps: S1: Take manganese ore, add ferrous sulfate reducing agent, then add sulfuric acid and water to mix, stir evenly at a speed of 120r / min in a 75°C water bath, react for 65min, filter the mixed solution to obtain a leachate; The amount of ferrous sulfate added is 1.8 g / g manganese ore, the amount of sulfuric acid solution added is 0.9 g / g manganese ore, and the solid-liquid ratio is 10 mL / g; S2: Add 1.9 times the mass of barium sulfide crystals to the leaching solution, stir evenly in a constant temperature water bath at 85°C and react for 50 minutes, then let stand for 4 hours, filter and obtain a purified solution; S3: Take α-hydroxy-2-ethylhexylphosphinic acid, dissolve it in kerosene to prepare an extractant with a concentration of 220 g / L, then add a sodium hydroxide solution with a mass fraction of 30-40% for saponification, let it stand and separate until the organic phase: aqueous phase is 2:1, and a sodium soap extractant is obtained; adjust the pH of the aqueous phase to 4 with sulfuric acid; S4: The purified liquid is mixed with a sodium soap extractant, and the mixture is extracted at 27° C. for 12 minutes, and then allowed to stand for phase separation, and the lower aqueous phase is taken out for suction filtration to obtain a manganese sulfate solution.

[0026] The preparation method of the α-hydroxyalkylphosphinic acid is as follows: A1: Heptanal and a 50% by mass aqueous solution of hypophosphorous acid are mixed at a molar ratio of 1.4:1, 1,4-dioxane is added as an organic solvent, and the mixture is heated to condense and reflux in the presence of concentrated hydrochloric acid at a heating temperature of 75° C. and a reaction time of 3-5 h to obtain a mixture; A2: Cool the mixture to room temperature, add 7% sodium hydroxide aqueous solution until the pH of the aqueous phase is greater than 10, separate the liquids and retain the aqueous phase; A3: Add 10% hydrochloric acid solution to the aqueous phase until the pH is less than 3, add an appropriate amount of ethyl acetate to extract three times, and retain the organic phase; A4: The organic phase was washed three times with saturated brine, dried over anhydrous sodium sulfate, and rotary evaporated at 55° C. to obtain α-hydroxy-2-ethylhexylphosphinic acid.

[0027] The organic phase manganese sulfate extraction rate of this embodiment is 98.92%, the aqueous phase magnesium extraction rate is 10.82%, and the zinc extraction rate is 10.24%.

[0028] The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. A method for extracting and producing battery-grade manganese sulfate, characterized in that: The following steps are involved: S1: Take manganese ore, add ferrous sulfate reducing agent, then add sulfuric acid and water to mix, stir evenly at a speed of 100-150r / min in a water bath at 70-90°C, react for 30-50min, filter the mixed solution, and obtain a leachate; The amount of ferrous sulfate added is 1.6-2.4 g / g manganese ore, the amount of sulfuric acid solution added is 0.7-1.0 g / g manganese ore, and the solid-liquid ratio is 6-12 mL / g; S2: Add 1.8 to 2.1 times the mass of barium sulfide crystals to the leaching solution, stir evenly in a constant temperature water bath at 70 to 90°C and react for 40 to 80 minutes, then let stand for 4 to 4 hours, filter and obtain a purified solution; S3: Take α-hydroxy-2-ethylhexylphosphinic acid, dissolve it in kerosene to prepare an extractant with a concentration of 150-250 g / L, then add a sodium hydroxide solution with a mass fraction of 30-40% for saponification, and stand to separate the phases until the organic phase: aqueous phase is (1-3): 1, to obtain a sodium soap extractant; S4: Mix the purified liquid with a sodium soap extractant, extract at 25-30° C. for 10-15 minutes, then allow to stand for phase separation, remove the lower aqueous phase and filter to obtain a manganese sulfate solution.

2. The method for producing battery-grade manganese sulfate by extraction according to claim 1, characterized in that: The preparation method of the α-hydroxyalkylphosphinic acid is as follows: A1: Heptanal and a 50% by mass hypophosphorous acid aqueous solution are mixed in a molar ratio of (1.2-1.5):1, 1,4-dioxane is added as an organic solvent, and the mixture is heated to condense and reflux in the presence of concentrated hydrochloric acid at a temperature of 70-90° C. and a reaction time of 3-5 hours to obtain a mixture; A2: Cool the mixture to room temperature, add 7% sodium hydroxide aqueous solution until the pH of the aqueous phase is greater than 10, separate the liquids and retain the aqueous phase; A3: Add 10% hydrochloric acid solution to the aqueous phase until the pH is less than 3, add an appropriate amount of ethyl acetate to extract three times, and retain the organic phase; A4: The organic phase was washed three times with saturated brine, dried over anhydrous sodium sulfate, and rotary evaporated at 55° C. to obtain α-hydroxy-2-ethylhexylphosphinic acid.

3. The method for producing battery-grade manganese sulfate by extraction according to claim 1, characterized in that: In step S3, the pH of the aqueous phase is adjusted to 3-5 using sulfuric acid.