A method for preparing high-purity manganese sulfate from low-grade rhodochrosite based on acetic acid and oxalic acid cycle

Abstract

The invention discloses a method for preparing high-purity manganese sulfate from low-grade rhodochrosite based on the cycle of acetic acid and oxalic acid. The invention uses low-grade rhodochrosite as a raw material, adds an acetic acid solution after pretreatment, fully stirs and heats to leach, performs solid-liquid separation after the reaction is completed, obtains a liquid-phase manganese acetate mother liquor and a solid-phase manganese slag; then adds oxalic acid to the manganese acetate mother liquor to generate a manganese oxalate precipitate, regenerates acetic acid, and the acetic acid solution after solid-liquid separation is circulated for leaching manganese ore powder. The manganese oxalate precipitate is put into a sulfuric acid solution for dissolution, and the temperature is simultaneously reduced to obtain a manganese sulfate solution and oxalic acid crystals, and the oxalic acid is circulated for acetic acid regeneration after solid-liquid separation. The invention uses manganese acetate as the first manganese extraction intermediate, can avoid direct contact between sulfuric acid and manganese slag, avoid sulfur in manganese slag, and is beneficial to the subsequent resource utilization of manganese slag; uses manganese oxalate as the second manganese extraction intermediate, can regenerate acetic acid for recycling, and can separate manganese from most heavy metal impurities, and easily obtain a high-purity manganese product.

Description

Technical Field

[0001] The invention relates to a technology for extracting manganese mineral resources, and in particular to a method for preparing high-purity manganese sulfate from low-grade rhodochrosite based on the cycle of acetic acid and oxalic acid, and belongs to the field of metallurgy and mineral processing. Background Art

[0002] With the rapid development of industrial fields such as batteries and alloys, the demand for manganese is increasing. Although low-grade rhodochrosite (manganese content less than 10%) has a low grade and high impurity content, it is gradually becoming an important source of manganese resources due to its abundant reserves. However, traditional extraction methods, such as roasting sulfuric acid leaching, have many problems. In this method, sulfuric acid is in direct contact with manganese ore, resulting in residual sulfuric acid in the tailings. Even if alkaline substances such as lime are used for neutralization, although the tailings do not contain acid, their sulfur content is still at an unsuitable level and cannot directly meet industrial needs such as cement production. In addition, this method has high energy consumption and usually requires high-temperature roasting to volatilize sulfur elements, which increases the difficulty of using tailings. This process not only brings more serious environmental pollution problems, but also significantly increases the cost of development and utilization of manganese resources. At the same time, low-grade manganese ore has a high content of impurities such as calcium, and the purification cost of removing these impurities to obtain high-purity manganese sulfate is also high.

[0003] Under the current industrial development background, the extraction technology of low-grade rhodochrosite faces many challenges, and it is also in urgent need of technological breakthroughs to meet actual needs. In recent years, relevant research has made certain progress in the extraction technology of low-grade rhodochrosite. For example, Chinese invention patent CN106381387B proposes a method for preparing high-purity manganese phosphate from low-grade rhodochrosite leaching solution. The method uses sodium phosphate as a pH regulator and precipitant, and is based on the chemical coupling integrated process design idea, which can effectively improve the purity of the product. However, sodium phosphate has a high cost and large market price fluctuations, which increases the difficulty of cost control on the raw material side, thereby limiting the wide application of this technology in industrial production. Therefore, further developing efficient, energy-saving and environmentally friendly technical methods to meet the requirements of the development and utilization of low-grade rhodochrosite is not only an inevitable requirement for the development of the manganese industry, but also a key way to achieve sustainable development and utilization of manganese ore resources. Summary of the invention

[0004] In view of the technical problems of limited product application range and high energy consumption in the existing low-grade rhodochrosite extraction method, the present invention provides a method for preparing high-purity manganese sulfate from low-grade rhodochrosite based on acetic acid and oxalic acid circulation. Acetic acid and oxalic acid are both organic acids with good acidity and complexing effect, which can effectively dissolve the manganese element in manganese ore, and the generated organic acid salt is easy to separate. Based on this feature, the process of circulating acetic acid and oxalic acid into the reaction system provided by the present invention can not only efficiently leach the manganese resources in the ore, but also simultaneously remove calcium and magnesium impurities in the manganese intermediate product, and finally obtain a high-purity manganese sulfate solution.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A method for preparing high-purity manganese sulfate from low-grade rhodochrosite based on the cycle of acetic acid and oxalic acid, using acetic acid, oxalic acid and sulfuric acid in relay to convert low-grade rhodochrosite into high-purity manganese sulfate solution, acetic acid and oxalic acid are recycled in the process, specifically comprising the following steps:

[0007] S1. A low-grade rhodochrosite ore is used as a raw material, and an acetic acid solution is added thereto after pretreatment to carry out a leaching reaction. The leaching reaction is carried out under stirring and heating conditions. After the reaction is completed, solid-liquid separation is performed to obtain a liquid manganese acetate mother liquor and a solid manganese slag;

[0008] S2. Add oxalic acid to the manganese oxalate mother liquor obtained in S1 to react to generate manganese oxalate precipitate and acetic acid, and obtain acetic acid solution and manganese oxalate precipitate after solid-liquid separation, and the acetic acid solution is circulated for the leaching reaction of S1;

[0009] S3. The manganese oxalate precipitate is put into a sulfuric acid solution for reaction and the temperature is simultaneously reduced to obtain a high-purity manganese sulfate solution and oxalic acid crystals. After solid-liquid separation, the oxalic acid is recycled in S2 to achieve acetic acid regeneration.

[0010] Furthermore, in S1, the manganese content of rhodochrosite is 8wt%-9wt%.

[0011] Furthermore, in S1, the pretreatment is drying and / or crushing, and the crushing is crushing to less than 200 meshes.

[0012] Furthermore, in S1, the concentration of the acetic acid solution is 0.5-2 mol / L, the solid-liquid mass ratio of the mineral powder to the acetic acid solution is 1:2-3.5, the reaction temperature is 40-60°C, the reaction time is 1-2 hours, the pH value is controlled at 4.5-5.5, and the reaction generates manganese acetate, and the manganese element is effectively dissolved into the solution.

[0013] Furthermore, in S2, the ratio of the amount of oxalic acid to manganese acetate is 1.0-1.4, preferably 1.05-1.3, the reaction temperature is 60-80°C, and the reaction time is 1-2 hours. Manganese acetate reacts with oxalic acid to generate manganese oxalate precipitate and acetic acid, the manganese oxalate precipitate is separated in the process, and the acetic acid is recovered into the solution and returned to the ore powder leaching process.

[0014] Furthermore, in S2, the oxalic acid added is solid oxalic acid or an oxalic acid solution with a concentration of 0.5-2 mol / L.

[0015] Further, in S3, the reaction temperature is 5-10°C, the reaction time is 1-2 hours, the sulfuric acid concentration is 1-3 mol / L, and the molar ratio of sulfuric acid to manganese oxalate is 1.0-1.3, preferably 1.0-1.2. The manganese oxalate precipitate reacts with the sulfuric acid solution to generate a manganese sulfate solution and an oxalic acid precipitate. The generated manganese sulfate solution can be evaporated, cooled, etc. to obtain manganese sulfate crystals, and can also be directly used as a raw material for electrolytic manganese dioxide.

[0016] The method uses acetic acid as the first acid to contact and react with rhodochrosite powder to prepare manganese acetate solution as the first manganese extraction intermediate; uses oxalic acid as the second acid to react with the first intermediate manganese acetate, regenerates acetic acid for recycling, and uses manganese oxalate precipitation as the second manganese extraction intermediate to simultaneously remove most of calcium, magnesium and heavy metal impurities; uses sulfuric acid as the third acid to react with manganese oxalate solid, cools down to precipitate oxalic acid solid for recycling, and simultaneously obtains a high-purity manganese sulfate solution product.

[0017] The beneficial effects of the present invention are:

[0018] The present invention uses manganese acetate as the first manganese extraction intermediate, effectively avoiding direct contact between sulfuric acid and manganese slag, thereby preventing the introduction of sulfur in manganese slag, and providing favorable conditions for the subsequent resource utilization of manganese slag; using manganese oxalate as the second manganese extraction intermediate, both acetic acid can be regenerated for recycling, and manganese and most heavy metal impurities can be separated, and high-purity manganese products can be easily obtained. The process reaction conditions are mild, avoiding the energy consumption of traditional high-temperature smelting methods, while reducing the use and discharge of toxic substances, meeting green environmental protection requirements. Acetic acid and oxalic acid can be effectively recovered in the reaction and recycled in the entire process, thereby reducing raw material consumption and reducing production costs. The process flow of the present invention is simple, easy to operate, and suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the reaction principle diagram of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to specific embodiments, but the present invention is not limited thereto. Example 1

[0021] 500g of low-grade rhodochrosite (manganese content of 9wt%) from a certain place was crushed through a 200-mesh sieve, and the resulting ore powder was added to an acetic acid solution with a concentration of 1mol / L for leaching reaction. The solid-liquid mass ratio of the ore powder to the acetic acid solution was 1:2.5, the leaching temperature was 50°C, the leaching time was 1.5 hours, and the pH value was controlled at 4.5. The manganese acetic acid solution obtained by the reaction reacted with an oxalic acid solution with a concentration of 1mol / L, the molar ratio of oxalic acid to manganese acetic acid was 1.3, the reaction temperature was 70°C, the reaction time was 1.5 hours, and manganese oxalate precipitate and acetic acid were generated. Subsequently, the manganese oxalate precipitate was reacted with a sulfuric acid solution with a concentration of 2mol / L, the molar ratio of sulfuric acid to manganese oxalate was 1.2, the reaction temperature was 8°C, and the reaction time was 1.5 hours to obtain a manganese sulfate solution and an oxalic acid precipitate. The manganese sulfate solution was crystallized to obtain a high-purity manganese sulfate product, and the purity was measured to be 99.6%. Example 2

[0022] 500g of low-grade rhodochrosite (manganese content of 8wt%) from a certain place was crushed through a 200-mesh sieve, and the resulting ore powder was added to an acetic acid solution with a concentration of 0.5mol / L for leaching reaction. The solid-liquid mass ratio of the ore powder to the acetic acid solution was 1:2.5, the leaching temperature was 40°C, the leaching time was 2 hours, and the pH value was controlled at 5.0. The manganese acetic acid solution obtained by the reaction reacted with an oxalic acid solution with a concentration of 2mol / L, the molar ratio of oxalic acid to manganese acetic acid was 1.05, the reaction temperature was 80°C, the reaction time was 1 hour, and manganese oxalate precipitate and acetic acid were generated. Subsequently, the manganese oxalate precipitate was reacted with a sulfuric acid solution with a concentration of 1mol / L, the molar ratio of sulfuric acid to manganese oxalate was 1.0, the reaction temperature was 5°C, and the reaction time was 2 hours to obtain a manganese sulfate solution and an oxalic acid precipitate. The manganese sulfate solution was crystallized to obtain a high-purity manganese sulfate product, and the purity was measured to be 99.2%. Example 3

[0023] 500g of low-grade rhodochrosite (manganese content of 8.8wt%) from a certain place was crushed through a 200-mesh sieve, and the resulting ore powder was added to an acetic acid solution with a concentration of 2mol / L for leaching reaction. The solid-liquid mass ratio of the ore powder to the acetic acid solution was 1:3, the leaching temperature was 60°C, the leaching time was 1 hour, and the pH value was controlled at 5.5. The manganese acetic acid solution obtained by the reaction reacted with an oxalic acid solution with a concentration of 2mol / L, the molar ratio of oxalic acid to manganese acetic acid was 1.2, the reaction temperature was 60°C, the reaction time was 2 hours, and manganese oxalate precipitate and acetic acid were generated. Subsequently, the manganese oxalate precipitate was reacted with a sulfuric acid solution with a concentration of 3mol / L, the molar ratio of sulfuric acid to manganese oxalate was 1.3, the reaction temperature was 10°C, and the reaction time was 1 hour to obtain a manganese sulfate solution and an oxalic acid precipitate. The manganese sulfate solution was crystallized to obtain a high-purity manganese sulfate product, and the purity was determined to be 99.4%. Example 4

[0024] 500g of low-grade rhodochrosite (manganese content of 8.7wt%) from a certain place was crushed through a 200-mesh sieve, and the resulting ore powder was added to an acetic acid solution with a concentration of 1.5mol / L for leaching reaction. The solid-liquid mass ratio of the ore powder to the acetic acid solution was 1:3.5, the leaching temperature was 50°C, the leaching time was 2 hours, and the pH value was controlled at 5.0. The manganese acetic acid solution obtained by the reaction reacted with an oxalic acid solution with a concentration of 2mol / L, the molar ratio of oxalic acid to manganese acetic acid was 1.1, the reaction temperature was 70°C, the reaction time was 2 hours, and manganese oxalate precipitate and acetic acid were generated. Subsequently, the manganese oxalate precipitate was reacted with a sulfuric acid solution with a concentration of 1mol / L, the molar ratio of sulfuric acid to manganese oxalate was 1.1, the reaction temperature was 7°C, and the reaction time was 1.5 hours to obtain a manganese sulfate solution and an oxalic acid precipitate. The manganese sulfate solution was crystallized to obtain a high-purity manganese sulfate product, and the purity was measured to be 99.2%. Example 5

[0025] This example uses the acetic acid and oxalic acid recovered multiple times in Example 1 to conduct a circulation experiment to explore the stability of the present invention.

[0026] Repeat all steps in Example 1, and carry out multiple circulation experiments by recovering acetic acid and oxalic acid. Monitor the change of acid solution after each round of reaction, and analyze the manganese concentration in manganese sulfate solution. In the circulation experiment, the recovery rate of acetic acid and oxalic acid reaches more than 90%, and the dissolution rate of manganese after each round of reaction is always maintained at more than 75%. Through multiple circulations, acetic acid and oxalic acid in the reaction system remain stable, no obvious concentration decrease occurs, and the purity of manganese sulfate solution can still reach 99%. This embodiment shows that acetic acid and oxalic acid remain stable in the promotion of reaction during the recycling process, and the utilization efficiency of resources can be effectively improved. Example 6

[0027] This example is a 10 kg scale scale test of Example 1.

[0028] Take 10kg of low-grade rhodochrosite powder sample, dry it and add it to 200L of 1mol / L acetic acid solution, the solid-liquid mass ratio is 1:2.5, the reaction temperature is set to 60°C, the reaction time is 1.5 hours, and the pH value is controlled at 5.0. The obtained manganese acetate solution is mixed with 1mol / L oxalic acid solution, the reaction temperature is 5°C, the leaching time is 2h, and manganese oxalate precipitate is generated, and acetic acid is released into the reaction system. The manganese oxalate precipitate is mixed with 2mol / L sulfuric acid solution, the reaction temperature is 50°C, the reaction time is 2h, a manganese sulfate solution is obtained, and the oxalic acid precipitate is separated. A high-purity manganese sulfate solution is obtained by crystallization, and the purity reaches 99%. The generated acetic acid and oxalic acid solutions are recovered and used again in the next reaction cycle. The process stability is evaluated by monitoring the manganese dissolution rate and the purity of the solution after each round of reaction. In the scale-up experiment, the recovery rate of acetic acid and oxalic acid reached more than 95%, the manganese dissolution rate of manganese sulfate solution was stable at more than 80%, and the purity was maintained at more than 99%. The scale-up experiment verified the feasibility of the process at the pilot scale, with stable process flow, high recycling efficiency and stable product quality. The process can be stably operated at an industrial scale, providing a feasible solution for the efficient utilization of low-grade rhodochrosite ore. Example 7

[0029] This example is a 100 kg pilot test of Example 1.

[0030] Take 100kg low-grade rhodochrosite powder sample, dry it and add 2m 3 The solid-liquid mass ratio was 1:2.5 in a 1mol / L acetic acid solution, the reaction temperature was set to 60°C, the reaction time was 1.5 hours, and the pH value was controlled at 5.0. The obtained manganese acetate solution was mixed with a 1mol / L oxalic acid solution, the reaction temperature was 5°C, the leaching time was 2h, a manganese oxalate precipitate was generated, and acetic acid was released into the reaction system. The manganese oxalate precipitate was mixed with a 2mol / L sulfuric acid solution, the reaction temperature was 50°C, the reaction time was 2h, a manganese sulfate solution was obtained, and the oxalic acid precipitate was separated. A high-purity manganese sulfate solution was obtained by crystallization, and the purity reached 99%. The generated acetic acid and oxalic acid solutions were recovered and used again in the next reaction cycle. The process stability was evaluated by monitoring the manganese dissolution rate and the purity of the solution after each round of reaction. In the scale-up experiment, the recovery rate of acetic acid and oxalic acid reached more than 95%, the manganese dissolution rate of manganese sulfate solution was stable at more than 80%, and the purity was maintained at more than 99%. The scale-up experiment verified the feasibility of the process at the pilot scale, the process flow was stable, the recycling efficiency was high, and the product quality was stable. The process can operate stably on an industrial scale, providing a feasible solution for the efficient utilization of low-grade rhodochrosite.

Claims

1. A method for preparing high-purity manganese sulfate from low-grade rhodochrosite based on the cycle of acetic acid and oxalic acid, characterized in that: The process uses acetic acid, oxalic acid and sulfuric acid to convert low-grade rhodochrosite into high-purity manganese sulfate solution. Acetic acid and oxalic acid are recycled in the process. The specific steps include: S1. A low-grade rhodochrosite with a manganese content of 8wt%-9wt% is used as a raw material, and an acetic acid solution is added thereto after pretreatment to carry out a leaching reaction. The leaching reaction is carried out under stirring and heating conditions, the concentration of the acetic acid solution is 0.5-2mol / L, the solid-liquid mass ratio of the ore powder to the acetic acid solution is 1:2~3.5, the reaction temperature is 40-60 ° C, the reaction time is 1-2 hours, the pH value is controlled at 4.5-5.5, and after the reaction is completed, solid-liquid separation is carried out to obtain a liquid manganese acetate mother liquor and a solid manganese slag; S2. Add oxalic acid to the manganese oxalate mother liquor obtained in S1 to react to generate manganese oxalate precipitate and acetic acid, the molar ratio of oxalic acid to manganese acetate is 1.0 to 1.4, the reaction temperature is 60-80 ° C, the reaction time is 1-2 hours, and after solid-liquid separation, an acetic acid solution and a manganese oxalate precipitate are obtained, and the acetic acid solution is circulated for the leaching reaction of S1; S3. The manganese oxalate precipitate is put into a sulfuric acid solution for reaction and the temperature is simultaneously reduced to obtain a manganese sulfate solution and oxalic acid crystals. After solid-liquid separation, the oxalic acid is recycled in S2 to achieve acetic acid regeneration.

2. The method for preparing high-purity manganese sulfate from low-grade rhodochrosite based on acetic acid and oxalic acid cycle according to claim 1, characterized in that: In S1, the pretreatment is drying and / or crushing, and the crushing is crushed to less than 200 meshes.

3. The method for preparing high-purity manganese sulfate from low-grade rhodochrosite based on acetic acid and oxalic acid cycle according to claim 1, characterized in that: The molar ratio of oxalic acid to manganese acetate is 1.05-1.

3.

4. The method for preparing high-purity manganese sulfate from low-grade rhodochrosite based on acetic acid and oxalic acid cycle according to claim 1, characterized in that: In S2, the oxalic acid added is solid oxalic acid or an oxalic acid solution with a concentration of 0.5-2 mol / L.

5. The method for preparing high-purity manganese sulfate from low-grade rhodochrosite based on acetic acid and oxalic acid cycle according to claim 1, characterized in that: In S3, the reaction temperature is 5-10°C, the reaction time is 1-2 hours, the sulfuric acid concentration is 1-3 mol / L, and the molar ratio of sulfuric acid to manganese oxalate is 1.0-1.

3.

6. The method for preparing high-purity manganese sulfate from low-grade rhodochrosite based on acetic acid and oxalic acid cycle according to claim 1, characterized in that: The molar ratio of sulfuric acid to manganese oxalate is 1.0-1.

2.

7. The method for preparing high-purity manganese sulfate from low-grade rhodochrosite based on acetic acid and oxalic acid cycle according to claim 1, characterized in that: In S3, the generated manganese sulfate solution is evaporated or cooled to obtain manganese sulfate crystals, or is directly used for electrolysis of manganese dioxide raw materials.

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