Multi-treatment method for manganese-based tailings

Abstract

The invention relates to the technical field of manganese-based material recovery, in particular to a manganese-based tailing multi-treatment method, which comprises the following steps: crushing and grinding manganese sulfate tailings to a target particle size, adding a pyrophosphoric acid solution for pretreatment, and performing microwave activation and dissolution to obtain a pretreated leachate; adjusting the pH value, adding amino modified hydroxyethylidene diphosphonic acid for complexing and removing impurities, removing arsenic through barium salt, performing secondary purification through hydrogen peroxide, and removing calcium and magnesium through phosphonate; subsequently, accurately filtering and intercepting impurities through a ceramic membrane, and performing vacuum crystallization, washing and drying to obtain high-purity manganese sulfate. According to the method, a multi-stage synergistic treatment system is constructed through the working procedures of crushing and grinding the manganese sulfate tailings, performing microwave activation and dissolution, complexing amino modified phosphonic acid to remove impurities, performing targeted calcium and magnesium removal through phosphonate, performing precise filtration through a ceramic membrane, performing vacuum crystallization and the like. All links have a synergistic effect to improve the purity of manganese sulfate and the recovery rate of manganese, calcium and magnesium residues are reduced, resource utilization of manganese-based tailings is achieved, and the product can stably adapt to application scenes of battery-grade and pharmaceutical-grade high-purity manganese sulfate.

Description

Technical Field

[0001] This application relates to the field of manganese-based material recycling technology, specifically to a method for multiple treatments of manganese-based tailings. Background Technology

[0002] Manganese sulfate, a core raw material in battery materials, metallurgical additives, and agricultural micro-fertilizers, is currently being prepared in high purity and its solid waste is being utilized as a resource. The manganese-based tailings produced during manganese sulfate production are rich in impurities such as iron, copper, arsenic, calcium, and magnesium. Direct storage of these tailings not only occupies significant land resources but also easily leads to heavy metal leakage, polluting soil and groundwater. Therefore, the harmless disposal and resource recovery of manganese sulfate are urgently needed.

[0003] In existing technologies, the treatment of manganese-based tailings mostly employs a single acid leaching or alkali washing process, supplemented by neutralization and precipitation for impurity removal. In the leaching stage, conventional methods only dissolve manganese through acid and alkali, resulting in a low manganese leaching rate, and heavy metal impurities are simultaneously leached out and difficult to separate. In the impurity removal stage, extensive methods such as lime neutralization and sulfide precipitation are often used, which lack the removal of impurities such as arsenic, calcium, and magnesium, easily leading to insufficient purity of manganese sulfate products, which cannot meet the requirements of high-end applications such as battery-grade products.

[0004] Therefore, in response to the technical bottlenecks of low manganese leaching rate and poor product purity in existing manganese-based tailings treatment processes, developing a multi-stage treatment technology for manganese-based tailings has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] To address the aforementioned problems, this application provides a method for the multi-stage treatment of manganese-based tailings. This invention utilizes a combination of technologies, including pyrophosphate pretreatment-microwave activation synergistic leaching for impurity removal, amino-modified hydroxyethylidene diphosphonic acid ternary chelation for deep removal of heavy metals, barium salt-hydrogen peroxide oxidation precipitation for directional arsenic removal, organophosphonic acid selective coordination for calcium and magnesium removal, and ceramic membrane cross-flow filtration-vacuum crystallization for precise purification, to achieve efficient resource utilization of manganese-based tailings and preparation of high-purity manganese sulfate.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] This application provides a method for multiple treatments of manganese-based tailings, including the following steps:

[0008] Step 1. Add the manganese sulfate tailings to a jaw crusher for crushing, and then grind them into powder using a ball mill; add the ground tailings to a reaction vessel, adjust the pH value, add a pyrophosphate pretreatment agent solution, and stir and pretreat at room temperature to obtain a pretreated mixture; after the pretreatment is completed, activate the pretreated mixture with microwave to obtain an activated mixture; after the activated mixture cools to room temperature, separate it by vacuum filtration to obtain a pretreated leachate;

[0009] Step 2. Add a first sulfuric acid solution or sodium hydroxide solution to the pretreated leachate to adjust the pH value of the system; add amino-modified hydroxyethylidene diphosphonic acid and stir to react. The amino-modified hydroxyethylidene diphosphonic acid is prepared by reacting hydroxyethylidene diphosphonic acid with an amination reagent. After the reaction is completed, let it stand and age, and filter it using a plate and frame filter press to remove the complex precipitate and obtain mixture A.

[0010] Step 3. Add a soluble barium salt solution to the mixture A and stir for the first reaction. After the reaction is complete, filter under vacuum to obtain the filtrate. Add hydrogen peroxide solution to the filtrate and stir for the second reaction. After the reaction is complete, let it stand at room temperature to precipitate, and then filter under vacuum to obtain the mixture B.

[0011] Step 4. Add an organophosphonic acid calcium and magnesium removal agent to the mixture B, adjust the pH of the system with sulfuric acid solution or sodium hydroxide solution, stir the reaction, after the reaction is completed, let it stand and age, and filter to obtain mixture C;

[0012] Step 5. The mixture C is fed into a ceramic membrane filtration system and filtered to obtain mixture D. The mixture D is then fed into a vacuum crystallizer and crystallized at a constant temperature to precipitate crystals. After crystallization, the crystals and mother liquor are separated by centrifugation, the crystals are washed with a second sulfuric acid solution, and the crystals are vacuum dried to obtain high-purity manganese sulfate.

[0013] Step 1 of this application increases the specific surface area of ​​manganese sulfate tailings through crushing and grinding, providing sufficient contact sites for subsequent multiphase reactions. After adding a pyrophosphate pretreatment agent solution under a weakly alkaline environment, the pyrophosphate (P2O7) groups are reduced... 4- Fe in tailings 3+ Cu 2+ Preferred coordination, because Fe 3+ Cu 2+ The complexation stability constant is higher than that of Mn. 2+ , and Fe 3+ Cu has a high charge density and a high charge number, resulting in extremely strong coordination bonds with pyrophosphate. 2+ With its d 9 Electronic configuration and Jahn-Teller distortion can interact with pyrophosphate (P2O7). 4- ) forms a stable five-membered chelate ring, while Mn 2+ For 3D 5 It exhibits a semi-stable configuration and a weak tendency to complex. Microwave activation induces lattice distortion in the tailings through both thermal and non-thermal effects, lowering the ion leaching energy barrier and enhancing the reaction between pyrophosphate and Fe. 3+ Cu 2+ The coordination efficiency of Mn promotes the formation of stable and soluble complexes. 2+ Efficient dissolution from the crystal lattice; solid-liquid separation achieved by vacuum filtration, initially removing Fe.3+ Cu 2+ Impurities.

[0014] Step 2 involves adjusting the pH of the system to a suitable range using a first sulfuric acid or sodium hydroxide solution to provide an optimal chelating environment for the amino-modified hydroxyethylidene diphosphonic acid. This chelating agent is prepared by grafting hydroxyethylidene diphosphonic acid with an amination reagent, constructing a ternary chelate structure containing amino, hydroxyl, and phosphonic acid groups. On one hand, the amino group acts as a strong electron donor, and its lone pair electrons can further fill Fe... 3+ Cu 2+ The empty orbitals enhance the stability constant of the chelate through strengthened σ coordination and back-bonding π bonds; secondly, the introduction of amino groups increases the steric hindrance of the chelating agent molecule to some extent, making it more compatible with Fe. 3+ Cu 2+ The ionic radius and coordination geometry of Mn 2+ The low coordination space fit enhances chelation selectivity at the molecular structure level. Furthermore, the amino group, as a strongly polar hydrophilic group, improves the water solubility and dispersion uniformity of the chelating agent in weakly acidic leachate, ensuring the preservation of trace residual Fe. 3+ Cu 2+ Both can contact the chelating agent efficiently. After the reaction, the mixture is allowed to stand and age to allow the chelated precipitate to fully aggregate. The precipitate is then removed by filtration using a plate and frame filter press, achieving Fe... 3+ Cu 2+ Further removal yields a mixture A with low levels of heavy metal impurities.

[0015] In step 3, a soluble barium salt solution is first added to mixture A. The barium ions react with As in the system through an ion precipitation reaction. 5+ A sparingly soluble barium arsenate precipitate is formed, achieving preliminary removal of arsenic impurities. The precipitate is then separated by vacuum filtration to obtain the filtrate. Subsequently, hydrogen peroxide solution is added, and the hydrogen peroxide removes low-valent As from the filtrate through a redox effect. 3+ Oxidation to higher valence As 5+ The precipitate is further converted into a stable barium arsenate precipitate, while simultaneously oxidizing residual reducing impurities in the system, eliminating their interference with subsequent processes. After the reaction, the oxidized precipitate is allowed to settle fully at room temperature, and then removed by vacuum filtration, effectively removing arsenic impurities and residual reducing heavy metals to obtain mixture B.

[0016] In step 4, an organophosphonic acid calcium and magnesium removal agent is added to mixture B, which reacts with Ca through a selective coordination mechanism of phosphonic acid groups. 2+ Mg 2+ It forms a poorly soluble complex precipitate. The alkyl chain in its molecular structure enhances coordination selectivity through steric hindrance, reducing its interaction with Mn. 2+The system then undergoes competitive coordination; the pH is adjusted to 5.0-6.5 using a first sulfuric acid or sodium hydroxide solution to optimize the coordination reaction conditions and improve precipitation stability and reaction rate. After the reaction, the mixture is allowed to stand and age, causing the calcium-magnesium complex precipitate to agglomerate. The precipitate is then removed by filtration, yielding a mixed solution C with further improved purity.

[0017] In step 5, the mixture C is fed into a ceramic membrane filtration system. Utilizing the membrane's sieving effect, submicron-sized fine impurities are retained in the system. Cross-flow operation suppresses membrane fouling through hydrodynamic effects, maintaining stable filtration flux and separation efficiency, thus achieving deep purification of the system to obtain mixture D. Mixture D is then fed into a vacuum crystallizer, where manganese sulfate crystals are oriented to precipitate through the principle of solution supersaturation. After crystallization, the crystals and mother liquor are separated by centrifugation. A second sulfuric acid is used to remove trace impurity ions adsorbed on the crystal surface through surface adsorption-desorption effects, avoiding the introduction of new impurities. Finally, vacuum drying at low temperature prevents crystal deliquescence and oxidative deterioration, ultimately yielding a high-purity manganese sulfate product.

[0018] Preferably, in step 1, the pyrophosphate pretreatment agent solution includes any one of sodium pyrophosphate solution, potassium pyrophosphate solution, and disodium hydrogen pyrophosphate solution; the mass concentration of the pyrophosphate pretreatment agent solution is 5%-15%; the solid-liquid ratio of the ground tailings to the pyrophosphate pretreatment agent solution is 1:(3-5) (g / mL); and the pH value is 7-9.

[0019] Preferably, in step 1, the jaw crusher crushes the manganese sulfate tailings to a particle size ≤ 5 mm; the powder has a mesh size of 100-200 mesh; the stirring speed of the stirring pretreatment is 200-300 r / min and the stirring time is 30-60 min; the microwave power of the microwave activation is 300-800 W, the temperature is 80-100℃, and the activation time is 5-20 min.

[0020] Preferably, in steps 2 and 4, the mass fraction of the first sulfuric acid solution is 5wt%-10wt%, and the mass fraction of the sodium hydroxide solution is 5wt%-8wt%; in step 2, the pH value is 3.5-5.5; the amination reagent includes any one of ethylenediamine, diethylenetriamine, and triethylenetetramine, and the mass ratio of the pretreatment leachate, the amination reagent, and hydroxyethylidene diphosphonic acid is 100:(0.2−0.6):(0.05−0.2).

[0021] Preferably, in step 2, the stirring speed of the stirring reaction is 150-250 r / min, the temperature is 40-60℃, and the stirring time is 60-90 min; the settling and aging time is 30-50 min.

[0022] Preferably, in step 3, the soluble barium salt solution includes barium chloride solution and barium nitrate solution; the mass fraction of the soluble barium salt solution is 10wt%-20wt%; the mass fraction of the hydrogen peroxide solution is 20wt%-40wt%; and the mass ratio of the mixture A, the soluble barium salt solution and the hydrogen peroxide solution is (80-100):(5-10):(1-3).

[0023] Preferably, in step 3, the stirring speed of the first stirring reaction is 150-200 r / min and the time is 30-40 min; the stirring speed of the second stirring reaction is 200-250 r / min, the temperature is 50-60℃ and the time is 40-60 min; and the settling time at room temperature is 40-60 min.

[0024] Preferably, in step 4, the organophosphonic acid calcium and magnesium removal agent includes any one of dioctyl phosphonate, octylphosphonic acid, and hexylphosphonic acid, and the mass ratio of the mixture B to the organophosphonic acid calcium and magnesium removal agent is 100:(0.1-0.5).

[0025] Preferably, in step 4, the pH value is 5.0-6.5; the stirring speed of the stirring reaction is 200-300 r / min, the stirring temperature is 60-70℃, and the time is 90-120 min; the standing aging time is 40-60 min.

[0026] Preferably, in step 5, the ceramic membrane in the ceramic membrane filtration system has a pore size of 50-200 nm, an operating pressure of 0.2-0.5 MPa, a filtration temperature of 40-50 °C, and a membrane flux of 100-150 L / (m²·h); the isothermal crystallization temperature is 60-70 °C and the time is 2-3 h; the mass fraction of the second sulfuric acid solution is 3wt%-6wt%, and the crystals are washed with the second sulfuric acid 2-3 times; the vacuum drying temperature is 80-100 °C and the time is 4-6 h.

[0027] Preferably, the filtration is cross-flow filtration.

[0028] Compared with the prior art, the beneficial effects of this application are as follows:

[0029] This application provides a method for the multi-stage treatment of manganese-based tailings. In this application, the manganese sulfate tailings are crushed and ground to increase their specific surface area, providing sufficient contact sites for subsequent multiphase reactions. A synergistic system is constructed using a pyrophosphate pretreatment agent and microwave activation. Microwaves induce lattice distortion in the tailings through thermal and non-thermal effects, reducing the ion leaching barrier and disrupting the mineral crystal lattice structure. This, on the one hand, enhances the interaction between pyrophosphate and Fe. 3+ and Cu 2+On the one hand, it improves the coordination efficiency, and on the other hand, it promotes the efficient dissolution of manganese ions from the tailings lattice into the liquid phase through lattice dissociation, thereby improving the manganese leaching recovery rate and achieving preliminary phase separation of impurities. Hydroxyethylidene diphosphonic acid is grafted and modified with an amination reagent to form a ternary chelate structure. This structure, in a suitable pH environment, binds with residual Fe through a chelation effect. 3+ and Cu 2+ It forms a stable chelate ring and selectively coordinates with manganese ions, achieving heavy metal ion removal through synergy with microwave-activated leaching, thus reducing manganese resource loss. Soluble barium salts and hydrogen peroxide optimize impurity removal efficiency through oxidation-precipitation. Barium salts react with arsenic ions via ion precipitation to form insoluble barium arsenate precipitate, while hydrogen peroxide converts low-valent arsenic to high-valent arsenic through redox reactions, improving the thermodynamic stability of the precipitate. Organophosphonic acid removers selectively react with Ca2+ via phosphonic acid groups. 2+ Mg 2+ Coordination forms insoluble complex precipitates, and the alkyl chains in their molecular structure enhance coordination selectivity through steric hindrance, reducing competition for coordination reactions with manganese ions. Through the mechanism coupling effect with a multi-stage impurity removal system, calcium and magnesium ions are removed. Cross-flow filtration of the ceramic membrane traps submicron-sized fine impurities in the system through membrane separation and sieving effects. Cross-flow operation suppresses membrane fouling through hydrodynamic effects, maintaining stable filtration flux and separation efficiency, thus further purifying the system. Subsequent vacuum crystallization achieves the directional precipitation of manganese sulfate crystals through the principle of solution supersaturation. Dilute sulfuric acid removes impurity ions adsorbed on the crystal surface through surface adsorption and desorption. Vacuum drying prevents crystal deliquescence and oxidative deterioration through low-temperature dehydration.

[0030] The entire system is interconnected and synergistically coupled, which improves the recovery rate of manganese resources while achieving the stepwise removal of impurities, ultimately producing high-purity manganese sulfate products. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a method for multiple treatment of manganese-based tailings provided by the present invention. Detailed Implementation

[0032] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the application will be further described in detail below with reference to embodiments. However, this should not be construed as limiting the scope of this application to the following examples. All other embodiments obtained by those skilled in the art without creative effort without departing from the above-described methodological spirit of this application are within the scope of protection of this application.

[0033] In this application, the terminology used is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0034] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.

[0035] The following will describe in detail, with reference to different embodiments, a method for multiple treatment of manganese-based tailings provided by this application.

[0036] Example 1

[0037] like Figure 1 As shown in the figure, this embodiment provides a method for multiple treatments of manganese-based tailings, including the following:

[0038] Step 1. Add manganese sulfate tailings to a jaw crusher and crush to a particle size ≤5mm, then grind to 100 mesh powder using a ball mill; add the ground tailings to a reaction vessel, adjust the pH to 7, add a 5% sodium pyrophosphate solution, the solid-liquid ratio of the ground tailings to the sodium pyrophosphate solution is 1:3 (g / mL), and pretreat by stirring at 200 r / min at room temperature for 30 min to obtain a pretreated mixture. After pretreatment, transfer the pretreated mixture to a microwave activation device and activate it at 300W microwave power and 80℃ for 5 min to obtain an activated mixture. After activation, wait for the activated mixture to cool to room temperature, and then separate it by vacuum filtration to obtain the pretreated leachate.

[0039] Step 2. Adjust the pH of the pretreated leachate to 3.5 using a 5wt% sulfuric acid solution; add amino-modified hydroxyethylidene diphosphonic acid, which is prepared by reacting hydroxyethylidene diphosphonic acid with ethylenediamine. The mass ratio of the pretreated leachate, ethylenediamine, and hydroxyethylidene diphosphonic acid is 100:0.2:0.05. Stir and react for 60 minutes at a stirring speed of 150 r / min and a temperature of 40°C. After the reaction is complete, allow it to stand for 30 minutes and filter it using a plate and frame filter press to remove the complex precipitate, obtaining mixture A.

[0040] Step 3. Slowly add a 10 wt% barium chloride solution to the mixture A, and stir at room temperature for 30 min at 150 r / min. After the reaction is complete, vacuum filter to remove the barium arsenate precipitate and obtain the filtrate. Add a 20 wt% hydrogen peroxide solution to the filtrate. The mass ratio of the mixture A, barium chloride solution and hydrogen peroxide solution is 80:5:1. Stir at 200 r / min and 50°C for 40 min. After the reaction is complete, allow to stand at room temperature for 40 min to precipitate, and then vacuum filter again to remove the secondary complexed precipitate to obtain the mixture B.

[0041] Step 4. Add dioctyl phosphonate to mixture B, wherein the mass ratio of mixture B to dioctyl phosphonate is 100:0.1; then adjust the pH of the system to 5.0 with 5wt% sulfuric acid solution, stir the reaction at 200 r / min and 60℃ for 90 min, after the reaction is completed, let it stand for 40 min, filter to obtain mixture C;

[0042] Step 5. The mixture C is fed into a ceramic membrane filtration system. A ceramic membrane with a pore size of 50 nm is selected. The operating pressure is controlled at 0.2 MPa, the filtration temperature at 40 °C, and the membrane flux at 100 L / (m²·h). Impurities in the system are removed by cross-flow filtration to obtain mixture D. Mixture D is then fed into a vacuum crystallizer and crystallized at 60 °C for 2 hours to precipitate manganese sulfate crystals. After crystallization, the crystals and mother liquor are separated by centrifugation. The crystals are washed twice with a 3 wt% second sulfuric acid solution. The crystals are then vacuum dried at 80 °C for 4 hours to obtain high-purity manganese sulfate.

[0043] Example 2

[0044] like Figure 1 As shown, this embodiment provides a method for multiple treatments of manganese-based tailings, including the following steps:

[0045] Step 1. Add manganese sulfate tailings to a jaw crusher and crush to a particle size ≤5mm, then grind to 150 mesh powder using a ball mill. Add the ground tailings to a reaction vessel, adjust the pH to 8, and add a 10% potassium pyrophosphate solution. The solid-liquid ratio of the ground tailings to the potassium pyrophosphate solution is 1:4 (g / mL). Stir and pretreat at room temperature and 250 r / min for 45 min to obtain a pretreated mixture. After pretreatment, transfer the pretreated mixture to a microwave activation device and activate it at 500W and 90℃ for 15 min to obtain an activated mixture. After activation, allow the activated mixture to cool to room temperature and separate it by vacuum filtration to obtain the pretreated leachate.

[0046] Step 2. Add a 6 wt% sodium hydroxide solution to the pretreated leachate to adjust the pH of the system to 4; add amino-modified hydroxyethylidene diphosphonic acid, which is prepared by reacting hydroxyethylidene diphosphonic acid and diethylenetriamine, with the mass ratio of the pretreated leachate, diethylenetriamine and hydroxyethylidene diphosphonic acid being 100:0.4:0.1. Stir and react at 200 r / min and 50℃ for 75 min. After the reaction is completed, let it stand for 40 min and filter it using a plate and frame filter press to remove the complex precipitate, obtaining mixture A.

[0047] Step 3. Add a 15 wt% barium nitrate solution to the mixture A, and stir at room temperature for 35 min at 170 r / min. After the reaction is complete, vacuum filter to remove the barium arsenate precipitate and obtain the filtrate. Add a 30 wt% hydrogen peroxide solution to the filtrate. The mass ratio of the mixture A, barium nitrate solution and hydrogen peroxide solution is 90:7:2. Stir at 220 r / min and 56°C for 50 min. After the reaction is complete, allow to stand at room temperature for 50 min to precipitate, and then vacuum filter again to remove the secondary complexed precipitate to obtain the mixture B.

[0048] Step 4. Add octylphosphonic acid to mixture B, wherein the mass ratio of mixture B to octylphosphonic acid is 100:0.2; then adjust the pH of the system to 6.0 with 7wt% sodium hydroxide solution, stir the reaction at 250 r / min and 65℃ for 110 min, after the reaction is completed, let it stand and age for 50 min, and filter to obtain mixture C;

[0049] Step 5. The mixture C is fed into a ceramic membrane filtration system. A ceramic membrane with a pore size of 100 nm is selected. The operating pressure is controlled at 0.3 MPa, the filtration temperature at 45 °C, and the membrane flux at 120 L / (m²·h). Impurities in the system are removed by cross-flow filtration to obtain mixture D. Mixture D is then fed into a vacuum crystallizer and crystallized at a constant temperature of 65 °C for 2.5 h to precipitate manganese sulfate crystals. After crystallization, the crystals and mother liquor are separated by centrifugation. The crystals are washed twice with a 4 wt% sulfuric acid solution and then vacuum dried at 90 °C for 5 h to obtain high-purity manganese sulfate.

[0050] Example 3

[0051] like Figure 1 As shown, this embodiment provides a method for multiple treatments of manganese-based tailings, including the following steps:

[0052] Step 1. Add manganese sulfate tailings to a jaw crusher and crush to a particle size ≤5mm, then grind to 200 mesh powder using a ball mill. Add the ground tailings to a reaction vessel, adjust the pH to 9, and add a 15% (w / w) disodium hydrogen pyrophosphate solution. The solid-liquid ratio of the ground tailings to the disodium hydrogen pyrophosphate solution is 1:5 (g / mL). Stir and pretreat at room temperature and 300 r / min for 60 min to obtain a pretreated mixture. After pretreatment, transfer the pretreated mixture to a microwave activation device and microwave activate at 800W and 100℃ for 20 min to obtain an activated mixture. After activation, allow the activated mixture to cool to room temperature and separate by vacuum filtration to obtain the pretreated leachate.

[0053] Step 2. Adjust the pH of the pretreated leachate to 5.5 using an 8wt% sodium hydroxide solution; add amino-modified hydroxyethylidene diphosphonic acid (HEDDI), which is prepared by reacting HEDDI with triethylenetetramine. The mass ratio of the pretreated leachate, triethylenetetramine, and HEDDI is 100:0.6:0.2. Stir the mixture at 250 r / min and 60°C for 90 min. After the reaction, allow it to stand for 50 min and filter using a plate and frame filter press to remove the complex precipitate, obtaining mixture A.

[0054] Step 3. Add a 20 wt% barium chloride solution to the mixture A, and stir at room temperature for 40 min at 200 r / min. After the reaction is complete, vacuum filter to remove the barium arsenate precipitate and obtain the filtrate. Add a 40 wt% hydrogen peroxide solution to the filtrate. The mass ratio of the mixture A, barium chloride solution and hydrogen peroxide solution is 100:10:3. Stir at 250 r / min and 60°C for 60 min. After the reaction is complete, allow to stand at room temperature for 60 min to precipitate, and then vacuum filter again to remove the secondary complexed precipitate and obtain the mixture B.

[0055] Step 4. Add hexylphosphonic acid to mixture B, wherein the mass ratio of mixture B to hexylphosphonic acid is 100:0.5; then adjust the pH of the system to 6.5 with 8wt% sodium hydroxide solution, stir the reaction at 300 r / min and 70℃ for 120 min, after the reaction is completed, let it stand for 60 min, filter to obtain mixture C;

[0056] Step 5. The mixture C is fed into a ceramic membrane filtration system. A ceramic membrane with a pore size of 200 nm is selected. The operating pressure is controlled at 0.5 MPa, the filtration temperature at 50 °C, and the membrane flux at 150 L / (m²·h). Impurities in the system are removed by cross-flow filtration to obtain mixture D. Mixture D is then fed into a vacuum crystallizer and crystallized at 70 °C for 3 hours to precipitate manganese sulfate crystals. After crystallization, the crystals and mother liquor are separated by centrifugation. The crystals are washed three times with a 6 wt% sulfuric acid solution and then vacuum dried at 100 °C for 6 hours to obtain high-purity manganese sulfate.

[0057] Comparative Example 1

[0058] A method for multiple treatment of manganese-based tailings, which differs from Example 3 in that unmodified hydroxyethylidene diphosphonic acid is used in step 2.

[0059] Comparative Example 2

[0060] A method for multiple treatment of manganese-based tailings, which differs from Example 3 in that the microwave activation step is omitted in step 1.

[0061] Comparative Example 3

[0062] A method for multiple treatment of manganese-based tailings, which differs from Example 3 in that step 4 is omitted, i.e., dioctyl phosphonate is not added to remove calcium and magnesium.

[0063] Comparative Example 4

[0064] A method for multiple treatment of manganese-based tailings, which differs from Example 3 in that it adopts the traditional "acid leaching-neutralization precipitation" process for acid leaching. The specific steps are as follows: the ground tailings are leached with a 10% sulfuric acid solution at room temperature, the pH of the leaching solution is adjusted to 7.0 with lime milk or caustic soda to form a precipitate, and after filtration, the filtrate is obtained. The subsequent steps are consistent with steps 3 and 5.

[0065] Performance testing:

[0066] 1. Manganese sulfate purity test: High-purity manganese sulfate obtained in Examples 1-3 and Comparative Examples 1-4 was dissolved in deionized water and filtered through a 0.22 μm filter membrane using a high-performance liquid chromatograph. The peak area of ​​manganese sulfate was determined by external standard method and the purity was calculated using potassium dihydrogen phosphate buffer as the mobile phase.

[0067] 2. Manganese recovery rate test: Using an atomic absorption spectrophotometer, the total manganese content in the raw material tailings of Examples 1-3 and Comparative Examples 1-4 and the manganese content in the final high-purity manganese sulfate were measured respectively. The ratio of the mass of manganese in the product to the total mass of manganese in the raw materials is the manganese recovery rate.

[0068] 3. Total calcium and magnesium residue test: Using an atomic absorption spectrophotometer, the high-purity manganese sulfate samples of Examples 1-3 and Comparative Examples 1-4 were digested with nitric acid using microwave, and the concentrations of calcium and magnesium ions were measured respectively. The sum of the two concentrations is the total calcium and magnesium residue.

[0069] The performance test data analysis is as follows:

[0070] Table 1. Performance test data of high-purity manganese sulfate obtained from Examples 1-3 and Comparative Examples 1-4

[0071]

[0072] Table 1 shows that, through the technical solutions of crushing and grinding, selective pyrophosphate complexation, microwave activation, amino-modified chelation for deep impurity removal, barium salt for arsenic removal, organophosphonic acid for calcium and magnesium removal, precision membrane filtration, and crystallization, the performance of Examples 1-3 showed an increasing trend. Example 3 performed best, with a manganese sulfate purity of up to 99.92%, a manganese recovery rate of 96.2%, and a total calcium and magnesium residue as low as 21 mg / kg, demonstrating high separation selectivity, recovery rate, and purification capability. This is due to the initial effect of pyrophosphate on Fe at pH 10. 3+ Cu 2+ The highly selective coordination and microwave activation synergistically lower the leaching barrier, achieving efficient dissociation of impurities and selective dissolution of manganese. Secondly, amino-modified hydroxyethylidene diphosphonic acid, with its amino-hydroxy-phosphonic acid ternary synergistic chelating structure, achieves deep-targeted removal of residual heavy metal ions. Simultaneously, the precise action of removal agents such as dioctyl phosphonate at optimized pH effectively removes alkaline earth metal impurities. Finally, cross-flow filtration using ceramic membranes and vacuum crystallization ensure the physical purity of the final product. The synergistic effect of each step achieves efficient recovery from tailings to high-purity manganese sulfate.

[0073] Compared to Example 3, Comparative Example 1 used unmodified hydroxyethylidene diphosphonic acid in step 2. The introduction of the missing amino group resulted in the chelating agent molecule losing its strong electron-donating ability and optimized steric hindrance effect, affecting the Fe... 3+ Cu 2+ The chelation selectivity and stability decreased. Residual heavy metal impurities were not completely removed, and the effect on Mn was also reduced. 2+ Increased competitive complexation led to a significant decrease in product purity (99.05%) and manganese recovery rate (89.2%). At the same time, co-precipitation of impurities may introduce more calcium and magnesium, increasing the residual amount to 85 mg / kg.

[0074] Compared to Example 3, Comparative Example 2 omits the microwave activation step in step 1. The lack of both the thermal and non-thermal effects of microwaves prevents the effective induction of lattice distortion in the tailings and the reduction of the ion leaching energy barrier, resulting in a decrease in the efficiency of the crucial first step of selective leaching. Fe 3+ Cu 2+ When impurity ions fail to be fully released and coordinate with pyrophosphate, Mn 2+ The dissolution of the substance was also insufficient, which weakened the separation basis of the entire process. All subsequent purification steps were operated under a higher impurity load, resulting in a final product purity of 98.82%, the lowest manganese recovery rate, and relatively high calcium and magnesium residues of 92 mg / kg.

[0075] Compared to Example 3, Comparative Example 3 completely omitted step 4 (i.e., no organophosphonic acid calcium and magnesium removal agent was added). Although the preceding steps were effective in removing heavy metals, calcium and magnesium ions were not specifically removed and ultimately almost all entered the product. Therefore, the total residual calcium and magnesium content was as high as 526 mg / kg, which directly reduced the product purity. The manganese recovery rate was 90.6%, indicating that the omission of this step had a relatively small direct impact on manganese.

[0076] Compared to Example 3, Comparative Example 4 uses a traditional "acid leaching-neutralization precipitation" process in step 1 instead of the "pyrophosphate pretreatment-microwave activation" of this application. Non-selective strong acid leaching causes all metal ions to dissolve simultaneously, resulting in poor selectivity and low efficiency of subsequent simple neutralization precipitation, and easily leading to co-precipitation loss of manganese. This results in low efficiency of impurity removal and significant manganese loss. Therefore, the purity (98.01%), recovery rate (84.8%), and calcium and magnesium residue (615 mg / kg) are the worst among all examples and comparative examples, highlighting the overall superiority of the multi-selective treatment process of this application.

[0077] In summary, Examples 1-3 achieved high-purity, high-yield, and low-impurity recovery of manganese sulfate from manganese sulfate tailings through multi-stage synergy and process parameter optimization, including enhanced crushing and grinding, selective leaching with pyrophosphate-microwave synergy, deep impurity removal with amino-modified chelating agents, arsenic removal with barium salt gradient, targeted decalcification and magnesium removal with organophosphonic acid, and precision membrane filtration crystallization.

[0078] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A method for multiple treatments of manganese-based tailings, characterized in that, Includes the following steps: Step 1. Add the manganese sulfate tailings to a jaw crusher for crushing, and then grind them into powder using a ball mill; add the ground tailings to a reaction vessel, adjust the pH value, add a pyrophosphate pretreatment agent solution, and stir and pretreat under normal temperature conditions to obtain a pretreated mixture; After pretreatment, the pretreated mixture is activated by microwave to obtain an activated mixture. After the activated mixture is cooled to room temperature, it is separated by vacuum filtration to obtain the pretreated leachate. Step 2. Add a first sulfuric acid solution or sodium hydroxide solution to the pretreated leachate to adjust the pH value of the system; add amino-modified hydroxyethylidene diphosphonic acid and stir to react. The amino-modified hydroxyethylidene diphosphonic acid is prepared by reacting hydroxyethylidene diphosphonic acid with an amination reagent. After the reaction is completed, let it stand and age, and filter it using a plate and frame filter press to remove the complex precipitate and obtain mixture A. Step 3. Add a soluble barium salt solution to the mixture A and stir for the first reaction. After the reaction is complete, filter under vacuum to obtain the filtrate. Add hydrogen peroxide solution to the filtrate and stir for the second reaction. After the reaction is complete, let it stand at room temperature to precipitate, and then filter under vacuum to obtain the mixture B. Step 4. Add an organophosphonic acid calcium and magnesium removal agent to the mixture B, adjust the pH of the system with sulfuric acid solution or sodium hydroxide solution, stir the reaction, after the reaction is completed, let it stand and age, and filter to obtain mixture C; Step 5. The mixture C is fed into a ceramic membrane filtration system and filtered to obtain mixture D. The mixture D is then fed into a vacuum crystallizer and crystallized at a constant temperature to precipitate crystals. After crystallization, the crystals and mother liquor are separated by centrifugation, the crystals are washed with a second sulfuric acid solution, and the crystals are dried under vacuum to obtain high-purity manganese sulfate.

2. The method for multiple treatment of manganese-based tailings according to claim 1, characterized in that, In step 1, the pyrophosphate pretreatment agent solution includes any one of sodium pyrophosphate solution, potassium pyrophosphate solution, and disodium hydrogen pyrophosphate solution; the mass concentration of the pyrophosphate pretreatment agent solution is 5%-15%; the solid-liquid ratio of the ground tailings and the pyrophosphate pretreatment agent solution is 1:(3-5) (g / mL); and the pH value is 7-9.

3. The method for multiple treatment of manganese-based tailings according to claim 1, characterized in that, In step 1, the jaw crusher crushes the manganese sulfate tailings to a particle size ≤ 5 mm; the powder has a mesh size of 100-200 mesh; the stirring speed of the stirring pretreatment is 200-300 r / min and the stirring time is 30-60 min; the microwave activation has a microwave power of 300-800 W, a temperature of 80-100℃, and an activation time of 5-20 min.

4. The method for multiple treatment of manganese-based tailings according to claim 1, characterized in that, In steps 2 and 4, the mass fraction of the first sulfuric acid solution is 5wt%-10wt%, and the mass fraction of the sodium hydroxide solution is 5wt%-8wt%. In step 2, the pH value is 3.5-5.

5. The amination reagent includes any one of ethylenediamine, diethylenetriamine, and triethylenetetramine. The mass ratio of the pretreatment leachate, the amination reagent, and hydroxyethylidene diphosphonic acid is 100:(0.2−0.6):(0.05−0.2).

5. The method for multiple treatment of manganese-based tailings according to claim 1, characterized in that, In step 2, the stirring speed of the stirring reaction is 150-250 r / min, the temperature is 40-60℃, and the stirring time is 60-90 min; the standing and aging time is 30-50 min.

6. The method for multiple treatment of manganese-based tailings according to claim 1, characterized in that, In step 3, the soluble barium salt solution includes barium chloride solution and barium nitrate solution; the mass fraction of the soluble barium salt solution is 10wt%-20wt%; the mass fraction of the hydrogen peroxide solution is 20wt%-40wt%; the mass ratio of the mixture A, the soluble barium salt solution and the hydrogen peroxide solution is (80-100):(5-10):(1-3).

7. The method for multiple treatment of manganese-based tailings according to claim 1, characterized in that, In step 3, the stirring speed of the first stirring reaction is 150-200 r / min and the time is 30-40 min; the stirring speed of the second stirring reaction is 200-250 r / min, the temperature is 50-60℃ and the time is 40-60 min; the settling time at room temperature is 40-60 min.

8. The method for multiple treatment of manganese-based tailings according to claim 1, characterized in that, In step 4, the organophosphonic acid calcium and magnesium removal agent includes any one of dioctyl phosphonate, octylphosphonic acid, and hexylphosphonic acid, and the mass ratio of the mixture B to the organophosphonic acid calcium and magnesium removal agent is 100:(0.1-0.5).

9. The method for multiple treatment of manganese-based tailings according to claim 1, characterized in that, In step 4, the pH value is 5.0-6.5; the stirring speed of the stirring reaction is 200-300 r / min, the stirring temperature is 60-70℃, and the time is 90-120 min; the standing aging time is 40-60 min.

10. The method for multiple treatment of manganese-based tailings according to claim 1, characterized in that, In step 5, the ceramic membrane in the ceramic membrane filtration system has a pore size of 50-200 nm, an operating pressure of 0.2-0.5 MPa, a filtration temperature of 40-50 °C, and a membrane flux of 100-150 L / (m²·h); the isothermal crystallization temperature is 60-70 °C and the time is 2-3 h; the mass fraction of the second sulfuric acid solution is 3wt%-6wt%, and the crystals are washed with the second sulfuric acid solution 2-3 times; the vacuum drying temperature is 80-100 °C and the time is 4-6 h.

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