Method for recovering iron and manganese from wolframite acidolysis wastewater

Abstract

The application belongs to the technical field of hydrometallurgy, and particularly relates to a method for recovering iron and manganese from wolframite acidolysis wastewater, which comprises the following steps: obtaining wolframite acidolysis wastewater containing Fe and Mn, adding a manganese-containing reagent into the wolframite acidolysis wastewater to adjust the pH to 4-4.5, filtering to obtain Fe(OH)3 and a manganese-containing filtrate; and using an ion exchange method, an extraction method or a precipitation method to treat the manganese-containing filtrate to recover manganese and obtain a manganese-containing product. The application prepares a by-product of iron hydroxide by adding a manganese-containing reagent, does not introduce other impurities in the process, and can subsequently enrich and recover the added reagent, reduces the use of additional consumables, and avoids resource waste; the self-made resin has higher exchange capacity and selectivity than traditional cation exchange resins, and improves the purity of the by-product of the manganese sulfate solution; through the graded recovery of iron and manganese, the purity of calcium sulfate generated by subsequent ammonia removal is high, and the calcium sulfate can be sold as a by-product, thereby significantly reducing the solid waste discharge amount of the whole process.

Description

Technical Field

[0001] This application belongs to the field of hydrometallurgical technology, specifically a method for recovering iron and manganese from acid hydrolysis wastewater of wolframite. Background Technology

[0002] The mainstream smelting process for wolframite concentrate is the alkaline process (such as soda ash boiling and alkaline decomposition), which mainly decomposes the mineral under high temperature and high pressure alkaline conditions. However, this process has problems such as long process flow, high energy consumption, large consumption of alkali agents, and potential generation of large amounts of high-salt wastewater pollution. In response, patent CN119351793A proposes a single sulfuric acid low-temperature roasting process to enhance the decomposition of wolframite and achieve efficient tungsten recovery. This method can significantly improve the tungsten conversion rate and leaching rate (>99% and >98%), replace high-priced alkali and high-pressure equipment, reduce solid waste and high-salt wastewater, and lower energy consumption and treatment costs. Patent CN108677037A uses sulfuric acid as the main leaching agent, extracts tungsten from the wolframite decomposition residue with hydrogen peroxide to form peroxytungstic acid, and then decomposes the tungstic acid through heating or SO2, achieving clean extraction without ammonia nitrogen wastewater. However, these existing technologies lack further treatment of the leaching solution and do not completely solve the wastewater discharge problem. The acid decomposition wastewater produced by the acid decomposition process of wolframite concentrate often has an extremely low pH and contains a large amount of heavy metal ions such as iron and manganese. The treatment of this wastewater generally adopts the calcium neutralization precipitation method, which requires the addition of a large amount of calcium oxide. For every ton of APT produced, about 3 to 4 tons of tailings are generated. Moreover, the calcium sulfate residue contains a large amount of iron and manganese solid impurities, so it cannot be used as a gypsum by-product and can only be outsourced for solid waste treatment, resulting in a waste of iron and manganese resources.

[0003] It is evident that if valuable metals in acid decomposition wastewater can be recovered and utilized at a high value while employing acid decomposition technology, it will provide a more efficient and cleaner alternative for the tungsten smelting industry. Summary of the Invention

[0004] To address the aforementioned problems, this application proposes a method for recovering iron and manganese from wollastonite acidolysis wastewater. This method is used to treat wollastonite acidolysis wastewater containing iron and manganese generated during the sulfuric acid decomposition process of wollastonite. This method can significantly reduce the generation of tailings and realize the resource utilization of iron and manganese in the wastewater.

[0005] This application provides a method for recovering iron and manganese from tungsten ore acidolysis wastewater, comprising the following steps: S1. Obtain wollastonite acid hydrolysis wastewater, wherein the wollastonite acid hydrolysis wastewater includes Fe and Mn. Add a manganese-containing reagent to the wollastonite acid hydrolysis wastewater to adjust the pH to 4-5, filter, and obtain Fe(OH)3 precipitate and manganese-containing filtrate. Recover the Fe(OH)3 precipitate. S2. The manganese-containing filtrate is treated by ion exchange, extraction or precipitation to recover manganese, resulting in a manganese-containing product and a manganese-recovered liquid, wherein the manganese-recovered liquid includes an ammonium sulfate solution.

[0006] Furthermore, in step S1, the manganese-containing reagent includes at least one of MnCO3 or Mn(OH)2.

[0007] Furthermore, in step S1, the concentration of Fe in the wolframite acid hydrolysis wastewater is 15~70 g / L, and the concentration of Mn is 20~80 g / L.

[0008] Furthermore, in step S1, the pH of the wolframite acidolysis wastewater is 1~2.5.

[0009] Furthermore, in step S1, the concentration of Fe in the manganese-containing filtrate is <1 mg / L, the recovery rate of Fe is >99.9%, and the purity of Fe(OH)3 is ≥99%.

[0010] Furthermore, in step S2, the specific method for recovering manganese from the manganese-containing filtrate using the ion exchange method is as follows: a. The resin is activated with ammonia water. The resin includes at least one of extraction resin or impregnation resin. The extraction resin is prepared by emulsion suspension polymerization using styrene as monomer, divinylbenzene as crosslinking agent, and P507, Cyanex272 or TBP as extractant. The impregnation resin is prepared using P507, Cyanex272 or TBP as extractant and YKDH-11 macroporous adsorption resin as carrier. b. The activated resin is used to perform ion exchange on the manganese-containing filtrate, and the exchanged solution is collected. The exchanged solution is an ammonium sulfate solution. c. The resin after ion exchange is desorbed using sulfuric acid to obtain the manganese-containing product, which is a manganese sulfate solution.

[0011] Furthermore, in step S2, the extraction method used to process the manganese-containing filtrate to recover manganese specifically involves: i. The manganese-containing filtrate is extracted with an organic solvent treated with ammonia water to obtain a loaded organic phase and a raffinate. The organic solvent includes an extractant, which includes at least one of P507, Cyanex272, TBP or pyridylcalix[4] aromatic hydrocarbons. The concentration of the extractant in the organic solvent is 5 vol% to 25 vol%. The raffinate is an ammonium sulfate solution. ii. The supported organic phase is back-extracted with sulfuric acid to obtain the manganese-containing product, which is a manganese sulfate solution.

[0012] Furthermore, in step S2, the specific method for recovering manganese from the manganese-containing filtrate using the precipitation method is as follows: Ammonium sulfide is added to the manganese-containing filtrate to adjust the pH to 5.5-7, and the mixture is filtered to obtain the manganese-containing product and the liquid after manganese precipitation. The manganese-containing product is manganese sulfide, and the liquid after manganese precipitation is an ammonium sulfate solution.

[0013] Furthermore, in step S2, the concentration of Mn in the ammonium sulfate solution is <1 mg / L, and the recovery rate of Mn is >99.9%.

[0014] Furthermore, after step S2, the method further includes: removing ammonia from the ammonium sulfate solution and adding a calcium-containing reagent to obtain calcium sulfate.

[0015] This application proposes a method for recovering iron and manganese from tungsten ore acidolysis wastewater, which produces the following beneficial effects: Iron hydroxide byproduct is prepared by adding a manganese-containing reagent without introducing other impurities, and the added reagent can be subsequently enriched and recovered, reducing the use of additional consumables and avoiding resource waste; the self-made resin has a higher exchange capacity and selectivity than traditional cation exchange resins, improving the purity of the manganese sulfate solution byproduct; through the graded recovery of iron and manganese, the calcium sulfate produced by subsequent deammoniation has a high purity and can be sold as a byproduct, significantly reducing the solid waste discharge of the entire process. Detailed Implementation

[0016] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0017] This application provides a method for recovering iron and manganese from tungsten ore acidolysis wastewater, comprising the following steps: S1. Obtain the acid hydrolysis wastewater of wolframite, which contains Fe and Mn. Add a manganese-containing reagent to the acid hydrolysis wastewater to adjust the pH to 4-5, filter, and obtain Fe(OH)3 precipitate and manganese-containing filtrate. Recover the Fe(OH)3 precipitate. The wastewater from the acidolysis of wolframite contains Fe concentrations of 15–70 g / L and Mn concentrations of 20–80 g / L; the pH of the wastewater is 1–2.5; the manganese-containing reagents include at least one of MnCO3 or Mn(OH)2; the Fe concentration in the obtained manganese-containing filtrate is <1 mg / L, the calculated Fe recovery rate is >99.9%, and the purity of Fe(OH)3 is ≥99%. Specifically, the Fe concentration in the wolframite acidolysis wastewater can be any one or a range between 15 g / L, 30 g / L, 45 g / L, 60 g / L, and 70 g / L; the Mn concentration can be any one or a range between 20 g / L, 40 g / L, 60 g / L, and 80 g / L; the pH of the wolframite acidolysis wastewater can be any one or a range between 1, 1.5, 2, and 2.5; and a manganese-containing reagent can be added to the wolframite acidolysis wastewater to adjust the pH to any one or a range between 4, 4.2, 4.4, 4.6, 4.8, and 5.0.

[0018] In step S1, the H+ in the scheelite acidolysis wastewater is consumed by adding a manganese-containing reagent. + This process raises the pH, causing the precipitation of high-purity ferric hydroxide, resulting in the production of ferric hydroxide as a byproduct. This process does not introduce other impurities. The resulting manganese-containing filtrate has a pH of 4-5, which is the optimal pH for manganese recovery via ion exchange (or extraction), eliminating the need for further pH adjustment with acid or alkali. Therefore, recovering iron through precipitation by pH control, followed by manganese recovery via ion exchange (or extraction), achieves two benefits simultaneously. If the pH is too low during iron precipitation, incomplete precipitation may occur, resulting in a high iron content in the manganese-containing filtrate and affecting the purity of the manganese product during recovery. Conversely, if the pH of the manganese-containing filtrate is too low when using ion exchange (or extraction) to recover manganese, the recovery rate will also decrease. If the pH is too high during iron precipitation, Fe(OH)3 will form colloids or fine particles, adsorbing other ions in the solution, resulting in impure Fe(OH)3 precipitation. This will also reduce the efficiency of solid-liquid separation and increase the cost of manganese carbonate reagent. In addition, if ion exchange (or extraction) is used to recover manganese, an excessively high pH in the manganese-containing filtrate will reduce the separation coefficient between manganese and other trace impurities in the solution during subsequent separation, affecting the product quality of manganese sulfate solution.

[0019] S2. Manganese-containing filtrate is treated by ion exchange, extraction or precipitation to recover manganese and obtain manganese-containing products. Specifically, the ion exchange method is used to treat manganese-containing filtrate and recover manganese. a. Pre-treat the resin and pack it into a column. The ratio of resin packing height to column diameter is (5~25):1, and the temperature is 20~80℃. Then, activate the resin with ammonia water of concentration 0.5~3mol / L. The flow rate of ammonia water during activation is 0.5~2BV / h. The resin includes at least one of extraction resin or impregnation resin. The extraction resin is prepared by emulsion suspension polymerization using styrene as monomer, divinylbenzene as crosslinking agent, and P507, Cyanex272 or TBP as extractant. The impregnation resin is prepared by using P507, Cyanex272 or TBP as extractant and YKDH-11 macroporous adsorption resin as carrier. b. Ion exchange of manganese-containing filtrate is carried out using activated resin. The flow rate of manganese-containing waste liquid during ion exchange is 0.5~2 BV / h. The post-exchange liquid is collected, which includes ammonium sulfate solution. c. Desorb the resin after ion exchange using 0.5~3 mol / L sulfuric acid. The flow rate of sulfuric acid during desorption is 0.5~2 BV / h, to obtain a manganese-containing product, which is a manganese sulfate solution.

[0020] Specifically, the concentration of ammonia can be any one of 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, or 3 mol / L, or any range between two of these; the concentration of sulfuric acid can be any one of 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, or 3 mol / L, or any range between two of these.

[0021] The extraction method for treating manganese-containing filtrate to recover manganese is as follows: i. The manganese-containing filtrate was extracted for 1 to 300 min by an organic solvent treated with ammonia water at a concentration of 0.5 to 3 mol / L. The volume ratio of the organic phase to the aqueous phase during extraction was (1:10) to (5:1). The loaded organic phase and raffinate were obtained. The organic solvent included an extractant, which included at least one of P507, Cyanex272, TBP or pyridylcalix[4] aromatic hydrocarbons. The concentration of the extractant in the organic solvent was 5 vol% to 25 vol%. The organic solvent also included a diluent or optional phase modifier. The diluent included at least one of kerosene or n-heptane. The phase modifier was a C5 to C10 straight (branched) chain alcohol. The raffinate was an ammonium sulfate solution. ii. The supported organic phase is back-extracted using 0.5~3 mol / L sulfuric acid. The volume ratio of the organic phase to the aqueous phase during back-extraction is (1:10)~(5:1) to obtain a manganese-containing product, which is a manganese sulfate solution.

[0022] Specifically, the concentration of ammonia can be any one or any two of 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, and 3 mol / L; the volume ratio of organic phase to aqueous phase during extraction can be any one or any two of 1:10, 1:1, 2:1, 3:1, 4:1, and 5:1; and the concentration of extractant in organic solvent can be any one or any two of 5%, 10%, 15%, 20%, and 25%. The concentration of sulfuric acid can be any one or any two of 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, and 3 mol / L; and the volume ratio of organic phase to aqueous phase during back-extraction can be any one or any two of 1:10, 1:1, 2:1, 3:1, 4:1, and 5:1.

[0023] The specific steps for recovering manganese from manganese-containing filtrate using the precipitation method are as follows: Ammonium sulfide was added to the manganese-containing filtrate to adjust the pH to 5.5-7. The reaction temperature was 20-60℃. After the reaction was completed, the solution was aged for 6-24 hours. The solution was filtered to obtain the manganese-containing product and the liquid after manganese precipitation. The manganese-containing product was manganese sulfide, and the liquid after manganese precipitation was ammonium sulfate solution.

[0024] In step S2, manganese is recovered from the manganese-containing filtrate by ion exchange, extraction, or precipitation. The concentration of Mn in the resulting ammonium sulfate solution is <1 mg / L, and the calculated Mn recovery rate is >99.9%. The extraction resin or impregnation resin used in the ion exchange method, and the organic solvent used in the extraction method, are all self-made and exhibit high selectivity for manganese. In particular, the self-made extraction resin has a higher exchange capacity and selectivity compared to traditional cation exchange resins, effectively separating manganese from other trace impurity ions (the selectivity of traditional cation exchange resins mainly depends on the ion valence state and hydration radius, and generally has a stronger affinity for ions with high valence and small hydration radius (such as Fe). 3+ >Ca 2+ >Mg 2+ >Mn 2+ ≈K + >Na + Therefore, for Mn 2+ The selectivity of [the extractant] is not prominent; while extraction resins, by solidifying the liquid extractant in a porous polymer, allow the H+ of organophosphorus extractants to [be enhanced] under acidic conditions. + With Mn in solution 2+ An exchange occurs, and simultaneously the phosphate groups in the extractant react with Mn. 2+By forming stable chelates and precisely controlling the acidity of the solution, manganese can be efficiently separated from other impurities. At the same time, optimizing the loading of the extractant during resin preparation can obtain the best exchange capacity. Therefore, the self-made extraction resin has higher selectivity and exchange capacity, resulting in a high purity of the manganese sulfate solution by-product.

[0025] Preferably, after step S2, the method further includes: removing ammonia from the ammonium sulfate solution and adding a calcium-containing reagent to obtain calcium sulfate, wherein the calcium-containing reagent includes calcium oxide; After separating iron and manganese by fractionation, the resulting ammonium sulfate solution contains fewer impurity ions. At this point, the traditional calcium neutralization precipitation method can be used to obtain calcium sulfate with higher purity.

[0026] The technical solution of this application will be further described below with reference to specific embodiments.

[0027] Example 1 500 mL of wollastonite acidolysis wastewater with a pH of 1.7 was obtained, containing 26.85 g / L Fe and 45.17 g / L Mn. MnCO3 solid powder was added to the wastewater and stirred thoroughly until the pH reached 5. The solution was then filtered, yielding 25.5 g of Fe(OH)3 precipitate and 511 mL of manganese-containing filtrate. The Fe(OH)3 precipitate had a purity ≥99% and could be sold as an industrial-grade product. The concentration of Mn in the manganese-containing filtrate was 85.3 g / L, and the concentration of Fe was 0.4 mg / L, resulting in a calculated Fe recovery rate of 99.998%. Manganese was recovered by treating the manganese-containing filtrate using an ion exchange method: CL-Cyanex 272 extraction resin was prepared using emulsion suspension polymerization, and the extraction resin was pretreated... The column was packed with a packing height to column diameter ratio of 10:1 at 25°C. The resin was activated by rinsing the exchange column with 3 mol / L ammonia at a flow rate of 1.2 BV / h. Then, the manganese-containing filtrate was passed through the exchange column at a flow rate of 1.2 BV / h, and 538 mL of the post-exchange solution was collected. The post-exchange solution was an ammonium sulfate solution with a Mn concentration of 0.5 mg / L. The calculated manganese recovery rate was 99.999%. Desorption was performed by passing 430 mL of 2.0 mol / L sulfuric acid solution through the exchange column at a flow rate of 1.2 BV / h to obtain a manganese-containing product, which was a battery-grade manganese sulfate solution (Fe concentration <0.01 ppm). After deammoniation of the ammonium sulfate solution, calcium oxide was added to obtain calcium sulfate as a byproduct.

[0028] Example 2 500 mL of wollastonite acidolysis wastewater with a pH of 1.7 was obtained, containing 26.85 g / L Fe and 45.17 g / L Mn. MnCO3 solid powder was added to the wastewater and stirred thoroughly until the pH reached 5. The solution was then filtered, yielding 25.5 g of Fe(OH)3 precipitate and 511 mL of manganese-containing filtrate. The Fe(OH)3 precipitate had a purity ≥99% and could be sold as an industrial-grade product. The concentration of Mn in the manganese-containing filtrate was 85.3 g / L, and the concentration of Fe was 0.4 mg / L, resulting in a calculated Fe recovery rate of 99.998%. Manganese was recovered from the manganese-containing filtrate using an extraction method: an organic solvent was prepared using Cyanex 272 as the extractant, 2-octanol as the phase modifier, and kerosene as the diluent, with a volume composition of 20% Cyanex 272, 30% octanol, and 2% octanol. 50% octanol and 50% kerosene were used to treat the organic solvent with 3 mol / L ammonia water, achieving a saponification degree of 100%. The manganese-containing filtrate was extracted with the treated organic solvent at 25℃, with an organic phase to aqueous phase volume ratio of 1:1 and an extraction time of 30 min. After extraction, 511 mL of raffinate was collected. The raffinate was an ammonium sulfate solution with a Mn concentration of 0.8 mg / L, and the calculated manganese recovery rate was 99.999%. The loaded organic phase was back-extracted with 2.0 mol / L sulfuric acid at a volume ratio of 1:1. After back-extraction, the back-extraction solution was collected, which was the manganese-containing product. This manganese-containing product was a battery-grade manganese sulfate solution (Fe concentration in the solution <0.01 ppm). After deammoniation of the ammonium sulfate solution, calcium oxide was added to obtain calcium sulfate as a byproduct.

[0029] Example 3 500 mL of wollastonite acidolysis wastewater with a pH of 1.7 was obtained, containing 26.85 g / L Fe and 45.17 g / L Mn. MnCO3 solid powder was added to the wastewater and stirred thoroughly until the pH reached 5. The solution was then filtered to obtain 25.5 g of Fe(OH)3 precipitate and 511 mL of manganese-containing filtrate. The Fe(OH)3 precipitate with a purity ≥99% is suitable for sale as an industrial-grade product. The manganese-containing filtrate contained 85.3 g / L Mn and 0.4 mg / L Fe. The calculated Fe recovery rate was 99.998%. Manganese was recovered from the manganese-containing filtrate using a precipitation method: 54g of ammonium sulfide reagent was added to the manganese-containing filtrate, and the mixture was stirred thoroughly. At this point, the pH of the solution was 6. After the reaction was completed, the solution was aged for 12 hours, and then filtered to obtain a manganese-containing product and 532mL of manganese-precipitated liquid. The manganese-containing product was manganese sulfide, and the manganese-precipitated liquid was ammonium sulfate solution. The concentration of Mn in the ammonium sulfate solution was 0.7mg / L, and the calculated manganese recovery rate was 99.999%. After deammoniation of the ammonium sulfate solution, calcium oxide was added to obtain calcium sulfate as a byproduct.

[0030] Example 4 500 mL of wolframite acidolysis wastewater with pH 1 was obtained, containing 31.65 g / L Fe and 40.78 g / L Mn. MnCO3 solid powder was added to the wastewater and stirred thoroughly until the pH reached 4. The solution was then filtered, yielding 30.28 g of Fe(OH)3 precipitate and 516 mL of manganese-containing filtrate. The Fe(OH)3 precipitate had a purity ≥99% and could be sold as an industrial-grade product. The concentration of Mn in the manganese-containing filtrate was 80.4 g / L, and the concentration of Fe was 0.6 mg / L, resulting in a calculated Fe recovery rate of 99.998%. Manganese was recovered by treating the manganese-containing filtrate using ion exchange. CL-Cyanex 272 extraction resin was prepared using emulsion suspension polymerization, and the extraction resin was pretreated... The column was packed with a packing height to column diameter ratio of 10:1 at 25°C. The resin was activated by rinsing the exchange column with 3 mol / L ammonia at a flow rate of 1.2 BV / h. Then, the manganese-containing filtrate was passed through the exchange column at a flow rate of 1.2 BV / h, and 522 mL of the post-exchange solution was collected. The post-exchange solution was an ammonium sulfate solution with a Mn concentration of 0.9 mg / L. The calculated manganese recovery rate was 99.999%. Desorption was performed by passing 420 mL of 2.0 mol / L sulfuric acid solution through the exchange column at a flow rate of 1.2 BV / h to obtain a manganese-containing product, which was a battery-grade manganese sulfate solution (Fe concentration <0.01 ppm). After deammoniation of the ammonium sulfate solution, calcium oxide was added to obtain calcium sulfate as a byproduct.

[0031] Example 5 500 mL of wollastonite acidolysis wastewater with a pH of 2.5 was obtained, containing 31.66 g / L Fe and 40.69 g / L Mn. MnCO3 solid powder was added to the wastewater and stirred thoroughly until the pH reached 4.2. The solution was then filtered, yielding 30.22 g of Fe(OH)3 precipitate and 515 mL of manganese-containing filtrate. The Fe(OH)3 precipitate had a purity ≥99% and could be sold as an industrial-grade product. The concentration of Mn in the manganese-containing filtrate was 81.6 g / L, and the concentration of Fe was 0.6 mg / L, resulting in a calculated Fe recovery rate of 99.998%. Manganese was recovered from the manganese-containing filtrate using an extraction method: an organic solvent was prepared using Cyanex 272 as the extractant, 2-octanol as the phase modifier, and kerosene as the diluent. The volume composition of the solvent was 20% Cyanex 272, 3% octanol, and 2% octanol. The organic solvent, consisting of 0% 2-octanol and 50% kerosene, was treated with 3 mol / L ammonia water to achieve 100% saponification. The manganese-containing filtrate was then extracted with the treated organic solvent at 25°C. The volume ratio of the organic phase to the aqueous phase was 1:1, and the extraction time was 30 min. After extraction, 519 mL of raffinate was collected. This raffinate was an ammonium sulfate solution with a Mn concentration of 0.8 mg / L, resulting in a manganese recovery rate of 99.999%. The supported organic phase was then back-extracted with 2.0 mol / L sulfuric acid at a volume ratio of 1:1. The back-extract was collected, yielding the manganese-containing product, a battery-grade manganese sulfate solution (Fe concentration <0.01 ppm). After deammoniation of the ammonium sulfate solution, calcium oxide was added to obtain calcium sulfate as a byproduct.

[0032] Comparative Example 1 500 mL of wolframite acidolysis wastewater with a pH of 1.7 was obtained, containing 26.85 g / L Fe and 45.17 g / L Mn. Manganese was recovered from the wolframite acidolysis wastewater using ion exchange. CL-Cyanex 272 extraction resin was prepared using emulsion suspension polymerization. After pretreatment, the resin was packed into a column with a packing height to column diameter ratio of 10:1 at 25°C. The resin was eluted with 3 mol / L ammonia solution at a flow rate of 1.2 BV / h. Activation was performed; then, the acid hydrolysis wastewater from wolframite was passed through an exchange column at a flow rate of 1.2 BV / h, and 498 mL of the post-exchange solution was collected. The concentration of Mn in the post-exchange solution was 20.56 g / L, and the concentration of Fe was 5.37 g / L. The calculated recovery rate of manganese was 54.67%, and the recovery rate of iron was 80.08%. Desorption was performed by passing 430 mL of 2.0 mol / L sulfuric acid solution through the exchange column at a flow rate of 1.2 BV / h, resulting in a mixed solution of iron and manganese sulfate, which could not be sold as a by-product.

[0033] It is evident that the order of iron and manganese recovery is specific. The presence of iron in the acid hydrolysis wastewater of wolframite will affect the purity of manganese sulfate byproducts. Furthermore, the pH of the pre-exchange solution during ion exchange has a significant impact on the manganese recovery rate. In this comparative example, the pH during ion exchange was 1.7, which is not the optimal pH for manganese recovery by ion exchange, and the recovery rates of both iron and manganese were significantly reduced.

[0034] Comparative Example 2 500 mL of wolframite acidolysis wastewater with pH 1.7 was obtained, containing Fe: 26.85 g / L and Mn: 45.17 g / L. Calcium oxide was added to the wolframite acidolysis wastewater to adjust the pH to 10, resulting in the formation of a large amount of precipitate. The precipitate was filtered to obtain a solid mixture of calcium sulfate, ferric hydroxide, and manganese hydroxide, which could not be sold as a byproduct.

[0035] Comparative Example 3 500 mL of wolframite acidolysis wastewater with pH 1.7 was obtained, containing 26.85 g / L Fe and 45.17 g / L Mn. MnCO3 solid powder was added to the wolframite acidolysis wastewater and stirred thoroughly until the pH of the solution reached 6. After filtration, 28.7 g of Fe(OH)3 precipitate and 516 mL of manganese-containing filtrate were obtained. The purity of the obtained Fe(OH)3 precipitate was <99% and it could not be sold as an industrial-grade product. The concentration of Fe in the manganese-containing filtrate was 0.4 mg / L and the concentration of Mn was 82.3 g / L. The Fe recovery rate was 99.998%. Manganese was recovered from manganese-containing filtrate using an ion exchange method: CL-Cyanex 272 extraction resin was prepared by emulsion suspension polymerization. The resin was pretreated and packed into a column with a packing height to column diameter ratio of 10:1 at 25℃. The resin was activated by rinsing the exchange column with 3 mol / L ammonia at a flow rate of 1.2 BV / h. Then, the manganese-containing filtrate was passed through the exchange column at a flow rate of 1.2 BV / h, and 538 mL of the after-exchange solution (ammonium sulfate solution) was collected. The concentration of Mn in the ammonium sulfate solution was 0.8 mg / L, and the calculated manganese recovery rate was 99.998%. Desorption was performed by passing 430 mL of 2.0 mol / L sulfuric acid solution through the exchange column at a flow rate of 1.2 BV / h, yielding a manganese-containing product, which was a manganese sulfate solution. The Fe concentration in the solution was <0.01 ppm, but the impurity contents of Ca, Mg, Co, and Ni were increased. After deammoniation of the ammonium sulfate solution, calcium oxide was added to obtain calcium sulfate as a byproduct.

[0036] It is evident that excessively high pH during iron precipitation will result in a Fe(OH)3 precipitate with a purity below 99%. This is primarily because excessively high pH causes Fe(OH)3 to form colloids or fine particles, which adsorb other ions in the solution, thus exacerbating impurity entrainment. Simultaneously, it reduces solid-liquid separation efficiency and increases the cost of manganese carbonate reagent. Furthermore, excessively high pH in the pre-exchange solution will reduce the separation coefficient between manganese and other trace impurity elements in the solution, affecting the product quality of manganese sulfate solution.

[0037] This application proposes a method for recovering iron and manganese from tungsten ore acidolysis wastewater, which produces the following beneficial effects: Iron hydroxide byproduct is prepared by adding a manganese-containing reagent without introducing other impurities, and the added reagent can be subsequently enriched and recovered, reducing the use of additional consumables and avoiding resource waste; the self-made resin has a higher exchange capacity and selectivity than traditional cation exchange resins, improving the purity of the manganese sulfate solution byproduct; through the graded recovery of iron and manganese, the calcium sulfate produced by subsequent deammoniation has a high purity and can be sold as a byproduct, significantly reducing the solid waste discharge of the entire process.

[0038] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for recovering iron and manganese from acid hydrolysis wastewater of wolframite, characterized in that, Includes the following steps: S1. Obtain wollastonite acid hydrolysis wastewater, wherein the wollastonite acid hydrolysis wastewater includes Fe and Mn. Add a manganese-containing reagent to the wollastonite acid hydrolysis wastewater to adjust the pH to 4-5, filter, and obtain Fe(OH)3 precipitate and manganese-containing filtrate. Recover the Fe(OH)3 precipitate. The manganese-containing reagent includes at least one of MnCO3 or Mn(OH)2; The concentration of Fe in the manganese-containing filtrate is <1 mg / L, the Fe recovery rate is >99.9%, and the purity of Fe(OH)3 is ≥99%. S2. Manganese is recovered by treating the manganese-containing filtrate using ion exchange or precipitation methods to obtain a manganese-containing product. The specific method for recovering manganese from the manganese-containing filtrate using the ion exchange method is as follows: a. The resin is activated with ammonia water. The resin includes at least one of extraction resin or impregnation resin. The extraction resin is prepared by emulsion suspension polymerization using styrene as monomer, divinylbenzene as crosslinking agent, and P507, Cyanex272 or TBP as extractant. The impregnation resin is prepared using P507, Cyanex272 or TBP as extractant and YKDH-11 macroporous adsorption resin as carrier. b. The activated resin is used to perform ion exchange on the manganese-containing filtrate, and the exchanged solution is collected. The exchanged solution is an ammonium sulfate solution. c. Desorb the resin after ion exchange using sulfuric acid to obtain the manganese-containing product, which is a manganese sulfate solution; The specific method for recovering manganese from the manganese-containing filtrate using the precipitation method is as follows: Ammonium sulfide was added to the manganese-containing filtrate to adjust the pH to 5.5-7, and the mixture was filtered to obtain the manganese-containing product and the liquid after manganese precipitation. The manganese-containing product was manganese sulfide, and the liquid after manganese precipitation was an ammonium sulfate solution. The concentration of Mn in the ammonium sulfate solution is <1 mg / L, and the recovery rate of Mn is >99.9%.

2. The method for recovering iron and manganese from wollastonite acidolysis wastewater according to claim 1, characterized in that, In step S1, the concentration of Fe in the wollastonite acid hydrolysis wastewater is 15~70 g / L, and the concentration of Mn is 20~80 g / L.

3. The method for recovering iron and manganese from wollastonite acidolysis wastewater according to claim 1, characterized in that, In step S1, the pH of the wolframite acidolysis wastewater is 1~2.

5.

4. The method for recovering iron and manganese from wollastonite acidolysis wastewater according to claim 1, characterized in that, The step S2 is followed by: removing ammonia from the ammonium sulfate solution and adding a calcium-containing reagent to obtain calcium sulfate.