Method for recycling insoluble manganese in electrolytic manganese residues

Abstract

The invention discloses a method for recycling insoluble manganese in electrolytic manganese residues. The method comprises the steps that the electrolytic manganese residues are crushed and finely ground; mixing the manganese slag with water, stirring and washing, and carrying out solid-liquid separation through filtering equipment; adding a magnetizing agent and an auxiliary agent into the washed filter residue, and carrying out magnetizing roasting; the roasted material is cooled to the room temperature, and then water is added to prepare ore pulp with the concentration being 20%-30%; the ore pulp sequentially passes through a magnetic separation device; a 10%-20% sulfuric acid solution is used as a leaching agent, the magnetic concentrate and the leaching agent are stirred and leached in a reaction kettle, and the solid-to-liquid ratio is 1: 3-1: 5; the leaching liquid and the leaching residues are separated through filtering equipment; an oxidizing agent is added into the leachate, and the pH value of the leachate is adjusted to 4-5; concentrating the leachate, adding ammonium sulfate to form an electrolyte, and feeding the electrolyte into an electrolytic bath for electrolysis; and after electrolysis is finished, a manganese metal product is obtained from the negative plate. And the recovery efficiency and benefits of insoluble manganese in the electrolytic manganese residues are effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical solid waste treatment, and specifically relates to a method for recovering insoluble manganese from electrolytic manganese slag. Background Art

[0002] The electrolytic manganese technology is an industrial production technology for producing metallic manganese from manganese-containing raw materials through an electrochemical method. Utilizing the solubility of manganese compounds in the electrolyte and the law of electron gain and loss of ions on the electrodes during the electrolysis process, under the action of direct current, manganese ions in the solution obtain electrons on the cathode surface and are reduced to metallic manganese, which is deposited on the cathode plate, thereby realizing the separation of manganese from other impurity elements and finally obtaining a metallic manganese product with higher purity. For example, commonly, using a manganese sulfate solution as the electrolyte, in the electrolytic cell, the manganese ions ionized from manganese sulfate move towards the cathode and react at the cathode to achieve the precipitation of metallic manganese.

[0003] A large amount of manganese slag is generated during the production of electrolytic manganese. These manganese slags contain soluble and insoluble manganese compounds. Among them, due to the limitations of the current production process, the acid leaching step in the electrolytic manganese production process cannot completely dissolve the manganese carbonate in the manganese ore. Therefore, a considerable amount of manganese carbonate remains in the electrolytic manganese slag. The insoluble manganese mainly exists in the form of manganese carbonate (MnCO3). Since it is not easily soluble in water, it is difficult to directly recover it through conventional water washing or acid washing methods. Manganese carbonate, as an important part of manganese resources, can be used to produce manganese concentrate powder, electrode materials for lithium-ion batteries, etc., and has high economic value. With the increasing shortage of manganese resources, recovering the residual manganese in manganese slag is also an important topic.

[0004] In the patent with the publication number CN115612845B, a method for the comprehensive component recovery of electrolytic manganese slag is disclosed. In this method, while leaching electrolytic manganese slag with sulfuric acid, calcium sulfate is made into calcium sulfate whiskers. The acid leaching residue is subjected to two-stage alkali leaching with sodium hydroxide, carbonized to prepare white carbon black, and the sodium hydroxide solution is recycled. After removing impurity ions from the acid leaching solution by neutralization precipitation, sulfide precipitation, and fluoride precipitation, manganese hydroxide is precipitated with ammonia water. Manganese hydroxide is dissolved with sulfuric acid to prepare a saturated manganese sulfate solution, and then high-purity manganese sulfate is prepared by heating and crystallization. This method reasonably treats other component impurities in the manganese slag, but there is no reasonable treatment method for manganese carbonate. Therefore, the efficiency and benefit of recovering manganese by the acid leaching method are relatively low. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for recovering insoluble manganese from electrolytic manganese slag to solve the following technical problems raised in the background art:

[0006] In the prior art, there are problems of low efficiency and low benefit when recovering manganese from manganese slag by the acid leaching method.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for recovering insoluble manganese in electrolytic manganese slag, comprising the following steps:

[0009] A1. Crush the electrolytic manganese slag and perform fine grinding; mix the manganese slag with water and stir and wash it, and perform solid-liquid separation through a filtering device.

[0010] A2. Add a magnetization agent and an auxiliary agent to the washed filter residue and mix evenly; magnetically roast the mixed material; cool the roasted material to room temperature, and then add water to adjust it into a pulp with a concentration of 20%-30%; pass the pulp through a magnetic separation device in sequence.

[0011] A3. Use a 10%-20% sulfuric acid solution as a leaching agent, stir and leach the magnetic concentrate and the leaching agent in a reaction kettle, and the solid-liquid ratio is 1:3-1:5; separate the leaching solution and the leaching residue through a filtering device; add an oxidizing agent to the leaching solution, and adjust the pH value of the leaching solution to 4-5; concentrate the leaching solution and add ammonium sulfate to form an electrolyte solution, and send the electrolyte solution into an electrolytic cell for electrolysis; after the electrolysis is completed, obtain a metallic manganese product from the cathode plate.

[0012] Further, in step A1, a jaw crusher is used to crush the electrolytic manganese slag, and the manganese slag particles are controlled to be 5-10 mm; a ball mill is used to finely grind the electrolytic manganese slag, and the particle size of the manganese slag is reduced to 0.044-0.074 mm by using the ball mill.

[0013] Further, in step A1, the manganese slag and water are mixed according to a solid-liquid ratio of 1:3-1:5.

[0014] Further, in step A1, after mixing the manganese slag and water, stir and wash them in a stirring tank, the stirring speed is 100-200 r / min, and the stirring time is 30-60 min.

[0015] Further, in step A2, the magnetization agent is pulverized coal or coke powder; the auxiliary agent is sodium carbonate or calcium carbonate.

[0016] Further, the addition amount of the magnetization agent is 5%-15% of the mass of the manganese slag, and the addition amount of the auxiliary agent is 2%-5% of the mass of the manganese slag.

[0017] Further, in step A2, magnetic roasting is carried out in a rotary kiln or a muffle furnace, the roasting temperature is controlled at 600-800 °C, and the roasting time is 1-3 h.

[0018] Further, in step A2, the magnetic separation device includes a weak magnetic separator and a strong magnetic separator. Among them, the magnetic field intensity of the weak magnetic separator is controlled at 100-300 mT, and the magnetic field intensity of the strong magnetic separator is controlled at 800-1500 mT.

[0019] Further, in step A3, a lead-silver alloy plate is used as the anode of the electrolytic cell, and a stainless steel plate is used as the cathode.

[0020] Further, during the electrolysis process, the cell voltage is controlled at 3 - 5V, the current density is 300 - 500 A / m2, and the electrolysis temperature is 35 - 45°C.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] By crushing and finely grinding the electrolytic manganese slag, the specific surface area of the manganese slag is increased in the present invention, making the insoluble manganese more likely to participate in the reaction during subsequent magnetization roasting and leaching processes, etc., creating favorable conditions for improving the recovery of manganese from the source. After adding a magnetization agent and an auxiliary agent and performing magnetization roasting, the insoluble manganese can be maximally converted into magnetic manganese minerals, and then the manganese is enriched through a magnetic separation device, effectively separating and enriching the manganese from the manganese slag, avoiding the waste of manganese resources, and greatly improving its recovery rate. Using sulfuric acid solution for leaching and subsequent electrolysis operations further ensures that the enriched manganese can be efficiently converted into metallic manganese products, making the entire process more thorough in the recovery of manganese resources.

[0023] In the present invention, elution to remove impurities removes soluble impurities such as sulfates and chlorides in the electrolytic manganese slag, avoiding interference of these impurities in subsequent processes, reducing the possibility of their mixing into the final product, and laying a foundation for obtaining high-purity metallic manganese. Adding an oxidizing agent to the leaching solution and adjusting the pH value to precipitate and remove impurities such as iron ions and aluminum ions further purifies the manganese-containing solution, ensuring the purity of the raw material entering the electrolysis link, and contributing to improving the purity of the final metallic manganese product. Washing and stripping the metallic manganese attached to the cathode plate after electrolysis and further processing can further remove surface impurities and improve the purity of the product.

[0024] In the present invention, operations such as washing to remove impurities and purifying the leaching solution to remove impurities avoid side reactions caused by the presence of impurities during magnetization roasting, leaching, electrolysis, etc., enabling the main reactions to proceed stably as expected, and ensuring the smoothness and operability of the entire recovery process flow. Concentrating and purifying the manganese solution and adding additives such as ammonium sulfate and boric acid to form an electrolyte optimize the conductivity, stability, and other properties of the electrolyte, contributing to maintaining the stability of various parameters during electrolysis, reducing abnormal situations caused by poor electrolyte performance, and improving the stability of the electrolysis link and the entire process flow.

[0025] The overall solution effectively improves the recovery efficiency and benefits of insoluble manganese in electrolytic manganese slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of the present invention;

[0027] Figure 2 One of the schematic structural diagrams of the magnetic separation device of the present invention;

[0028] Figure 3 Another schematic structural diagram of the magnetic separation device of the present invention;

[0029] Figure 4 Schematic internal structural diagram of the magnetic separation device of the present invention;

[0030] Figure 5 Schematic side view of the magnetic separation device of the present invention.

[0031] Markings in the figure: 1 - feed trough, 2 - drive motor, 3 - housing, 4 - discharge port, 5 - discharge chute, 6 - drum, 7 - blanking port, 8 - feed inlet, 9 - communication port, 10 - water supply pipe, 11 - blanking area, 12 - intermediate area, 13 - intermediate port, 14 - magnetic separation area, 15 - magnet, 16 - discharge communication port, 17 - flushing pipe, 18 - spray head, 19 - mounting shaft, 20 - mounting frame, 21 - adjustment motor, 22 - support frame, 23 - limiting rod, 24 - reciprocating lead screw, 25 - driving slider, 26 - driving rack, 27 - driving wheel. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] Embodiment:

[0034] A method for recovering insoluble manganese from electrolytic manganese slag, comprising the following steps:

[0035] A1. Crushing and finely grinding the electrolytic manganese slag; the electrolytic manganese slag usually has a relatively large and uneven particle size, which is not conducive to the full progress of subsequent reactions. Coarse crushing is carried out by equipment such as a jaw crusher, which can initially break the larger lumps of manganese slag into smaller particles, reducing the particle size level of the material; then, fine grinding is carried out by equipment such as a ball mill. Through this step, the specific surface area of the manganese slag can be greatly increased. The increase in the specific surface area means an increase in the contact area between the manganese slag and the subsequent treatment reagents, which can accelerate the reaction rate, improve the reaction efficiency, make the insoluble manganese more likely to participate in the reaction during the subsequent magnetization roasting and leaching processes, and thus improve the recovery efficiency of manganese.

[0036] Mix the manganese slag with water and stir - wash it, then perform solid - liquid separation through a filtration device. There are various soluble impurities in electrolytic manganese slag, such as sulfates, chlorides, etc. If these impurities are not removed, they may cause side reactions during subsequent magnetization roasting and leaching processes, affecting the recovery effect of manganese and may also corrode the equipment. Mixing the manganese slag with water according to a certain solid - liquid ratio and stirring - washing can dissolve the soluble impurities in water, and then realize solid - liquid separation through filtration. This step is simple and effective, and can provide relatively pure raw materials for subsequent processes.

[0037] A2, Add a magnetizing agent and an auxiliary agent to the washed filter residue and mix them evenly. Single roasting cannot effectively convert insoluble manganese into an available form. Adding magnetizing agents such as pulverized coal and coke powder can chemically react with insoluble manganese at high temperatures to convert it into magnetic manganese minerals. Auxiliary agents such as sodium carbonate and calcium carbonate can lower the activation energy of the reaction, promote the reaction, and improve the magnetization effect.

[0038] Perform magnetization roasting on the mixed material; Appropriate roasting temperature and time can maximize the conversion of insoluble manganese into magnetic manganese minerals.

[0039] Cool the roasted material to room temperature, and then add water to adjust it into a slurry with a concentration of 20% - 30%.

[0040] Pass the slurry through a magnetic separation device in sequence; Through the magnetic separation equipment, the manganese minerals can be adsorbed and separated to achieve the enrichment of manganese.

[0041] A3, Use a 10% - 20% sulfuric acid solution as the leaching agent, and stir - leach the magnetic concentrate and the leaching agent in a reaction kettle with a solid - liquid ratio of 1:3 - 1:5. The leaching agent can chemically react with the magnetic manganese minerals to dissolve manganese in the form of ions into the solution. Separate the leaching solution from the leaching residue through a filtration device; Add an oxidant to the leaching solution and adjust the pH value of the leaching solution to 4 - 5. After leaching, the leaching solution contains manganese ions, while the leaching residue is insoluble matter. Separating the two through a filtration device can obtain a pure manganese - containing solution, providing raw materials for subsequent electrolysis. In addition to manganese ions, the leaching solution may also contain impurities such as iron ions and aluminum ions. Add an oxidant to oxidize ferrous ions to ferric ions, and then adjust the pH value to precipitate iron ions, aluminum ions, etc. in the form of hydroxides. It should be noted that in this step, oxidants such as manganese dioxide and potassium permanganate are used as oxidants.

[0042] Specifically, in Embodiment 1, the solid-liquid ratio was fixed at 1:3, and experiments were carried out using sulfuric acid solutions with concentrations of 10%, 12%, 15%, 18%, and 20% respectively. Each time, the same mass of magnetite was accurately weighed and placed into the reaction kettle, and sulfuric acid solutions with corresponding concentrations were added according to the solid-liquid ratio. Stirring leaching reactions were carried out at the same temperature, the same stirring speed (such as 300 revolutions per minute), and the same reaction time. After the reaction ended, the leaching solution and the leaching residue were separated through a filtration device. The experimental results are as follows:

[0043] When the concentration of the sulfuric acid solution was 10%, due to the relatively low concentration, the driving force of the chemical reaction was relatively small. During the 2-hour reaction time, the manganese leaching rate was relatively low, the detected value of the manganese ion concentration in the leaching solution was at a medium level, and the corrosion of the equipment was relatively not serious, with only slight corrosion marks on the equipment surface.

[0044] As the concentration of the sulfuric acid solution increased to 12%, with other conditions being the same, the manganese leaching rate increased, the manganese ion concentration in the leaching solution increased compared with that at a concentration of 10%, and the corrosion degree of the equipment surface also began to become slightly more obvious, with a small number of corrosion spots appearing.

[0045] When the sulfuric acid concentration reached 15%, the manganese leaching rate further increased, and the manganese ion concentration in the leaching solution approached a relatively ideal level. However, the equipment corrosion was also more obvious, and there were obvious corrosion marks in some areas on the inner wall of the equipment, which might affect the service life of the equipment.

[0046] When the concentration was increased to 18%, the manganese leaching rate was relatively high, the manganese ion concentration in the leaching solution was relatively high, which could better meet the requirements for subsequent preparation of the electrolyte, but the equipment corrosion was serious, and there were many corrosion pits on the equipment surface, and the subsequent maintenance cost would inevitably increase.

[0047] When the concentration of the sulfuric acid solution reached 20%, the manganese leaching rate was the highest in this group of experiments, and the manganese ion concentration in the leaching solution was also the highest. However, the equipment faced serious corrosion problems, and it was very likely that the equipment needed to be repaired or replaced in the short term.

[0048] In Embodiment 2, the concentration of the sulfuric acid solution was selected as 15%. Based on the previous experiments, it was found that it was in a relatively appropriate concentration range and was convenient for comparative observation. Experiments were carried out using solid-liquid ratios of 1:3, 1:3.5, 1:4, 1:4.5, and 1:5 respectively. The same amount of magnetite was also weighed and placed into the reaction kettle, and sulfuric acid solution with a concentration of 15% was added to the corresponding solid-liquid ratio. The temperature, stirring speed, and reaction time were kept unchanged, and after the leaching reaction, the leaching solution and the leaching residue were separated.

[0049] When the solid-liquid ratio is 1:3, due to the relatively small amount of solution, the contact with magnetic concentrate is not sufficient, the manganese leaching rate is at an intermediate level, the manganese ion concentration in the leaching solution is relatively low, but the residual leaching solution in the equipment is relatively small, and the corrosion of the equipment is relatively limited.

[0050] When the solid-liquid ratio is adjusted to 1:3.5, the amount of solution increases, the contact between magnetic concentrate and sulfuric acid solution is more sufficient, the manganese leaching rate increases, the manganese ion concentration in the leaching solution rises accordingly, and the equipment corrosion situation is slightly aggravated, mainly due to the increase in the contact area with the solution.

[0051] When the solid-liquid ratio is 1:4, the leaching effect is further improved, the manganese leaching rate is further increased, the manganese ion concentration in the leaching solution can reach a relatively ideal level, and the equipment corrosion degree also increases accordingly, so the maintenance of the equipment needs to be appropriately concerned.

[0052] As the solid-liquid ratio increases to 1:4.5, the manganese leaching rate continues to increase, the manganese ion concentration in the leaching solution is higher, but there is more residual leaching solution in the equipment, the corrosion effect on the equipment is stronger, and the subsequent maintenance cost of the equipment will increase.

[0053] When the solid-liquid ratio reaches 1:5, the manganese leaching rate is the highest in this group of experiments, and the manganese ion concentration in the leaching solution is also the highest. However, the equipment corrosion situation is serious, and due to the large amount of solution, the energy consumption will also increase accordingly when concentrating and processing the leaching solution later, so the cost-benefit factors need to be comprehensively considered.

[0054] Based on the above experimental results, in a most preferred embodiment, the concentration of sulfuric acid solution is selected as 15%, and the solid-liquid ratio is selected as 1:3.5.

[0055] The leaching solution is concentrated and ammonium sulfate is added to form an electrolyte solution, and the electrolyte solution is sent into an electrolytic cell for electrolysis; the leaching solution is concentrated and the manganese ion concentration is adjusted to an appropriate range, and at the same time, additives such as ammonium sulfate and boric acid are added, which can improve the conductivity, stability and other properties of the electrolyte solution, and are beneficial to the smooth progress of the electrolysis process. Under specific conditions of cell voltage, current density and temperature, manganese ions obtain electrons at the cathode and are reduced to metallic manganese and deposited on the cathode plate. By controlling these parameters, the deposition rate and quality of manganese can be controlled.

[0056] After electrolysis, metallic manganese products are obtained from the cathode plate. The metallic manganese obtained by electrolysis adheres to the cathode plate, and metallic manganese products can be obtained through flushing and manganese stripping operations. Further processing can improve its purity and quality to meet different application requirements.

[0057] Finally, the wastewater generated during the electrolysis process and other steps contains heavy metal ions and other harmful substances. If directly discharged, it will cause serious pollution to the environment. Treatment methods such as chemical precipitation and ion exchange can be used to remove these harmful substances. The treated wastewater is recycled as production water, which can reduce water resource consumption, lower production costs, and achieve sustainable utilization of resources.

[0058] In a preferred embodiment, in step A1, a jaw crusher is used to crush the electrolytic manganese slag, and the manganese slag particles are controlled to be 5 - 10 mm; a ball mill is used to finely grind the electrolytic manganese slag, and the particle size of the manganese slag is reduced to 0.044 - 0.074 mm using the ball mill. Crushing the relatively large lumps of electrolytic manganese slag to 5 - 10 mm can make the subsequent fine grinding process of the ball mill smoother. When larger particles are ground in the ball mill, it will not only increase the load of the ball mill, extend the grinding time, but also may lead to uneven grinding. However, the moderate particle size after coarse crushing by the jaw crusher allows the ball mill to grind the manganese slag to the required fineness faster, improving the efficiency of the entire pretreatment stage. Reducing the particle size of the manganese slag to 0.044 - 0.074 mm greatly increases the specific surface area of the manganese slag. In the subsequent magnetization roasting process, a larger specific surface area means a significantly increased contact area between the manganese slag and the magnetizing agent and additives, which can accelerate the rate of the magnetization reaction and make the insoluble manganese more fully converted into magnetic manganese minerals. In the chemical leaching step, it can also make the leaching agent react more effectively with the manganese minerals, promoting the dissolution of the insoluble manganese and further improving the manganese recovery efficiency. The extremely fine particle size makes the insoluble manganese in the manganese slag easier to contact and react with the subsequent treatment reagents. In the magnetization roasting and leaching processes, the fine - grained manganese slag can participate in the reaction more fully, reducing the situation where the internal manganese cannot react due to overly large particles, thereby improving the effect and yield of the entire recovery process.

[0059] In a preferred embodiment, in step A1, the manganese slag and water are mixed at a solid-liquid ratio of 1:3 - 1:5. When the solid-liquid ratio is in the range of 1:3 - 1:5, the amount of water can meet the requirement for dissolving the soluble impurities in the manganese slag. If the solid-liquid ratio is too small, that is, the amount of water is relatively less, then the soluble impurities may not be completely dissolved in the water, resulting in some impurities still remaining in the manganese slag, thus affecting the effects of subsequent magnetization roasting and leaching processes and reducing the recovery efficiency of manganese. A suitable solid-liquid ratio can ensure that there is enough solvent to dissolve the impurities, enabling the impurities to enter the aqueous solution as much as possible. This solid-liquid ratio range makes the mixed slurry have appropriate fluidity and viscosity. If the solid-liquid ratio is too large and the amount of water is excessive, it will increase the difficulty and time cost of subsequent filtration separation, and at the same time increase the burden of wastewater treatment. At a solid-liquid ratio of 1:3 - 1:5, the filtration process can proceed smoothly, improving the efficiency of solid-liquid separation, and can reduce the water entrained in the filter residue, providing a more suitable raw material state for subsequent processes such as magnetization roasting. Adopting this preferred solid-liquid ratio can not only ensure the effect of washing and removing impurities but also avoid waste of water resources. In a preferred embodiment, the manganese slag and water are mixed at a solid-liquid ratio of 1:4. In this embodiment, when the solid-liquid ratio is 1:3, the amount of water is relatively at the lower limit value. Although it can dissolve some soluble impurities, due to the relatively small amount of solvent, for some soluble impurities with slightly higher content or slightly poorer solubility (such as some sulfates, chlorides, etc.), they may not be completely dissolved out of the manganese slag. Since the slurry is relatively viscous, the separation of the filter residue and the filtrate is relatively not so easy, and the filtration speed will be slightly slower, but it is still better than the case with a smaller solid-liquid ratio. The amount of water used is less, and relatively speaking, the waste of water resources is not obvious, and at the same time, the amount of wastewater generated subsequently is also less, which reduces the burden of wastewater treatment to a certain extent. From this perspective, it has certain advantages for environmental protection and cost control. In this embodiment, when the solid-liquid ratio is 1:4, this solid-liquid ratio can better meet the requirement for dissolving soluble impurities, and most common soluble impurities (such as common sulfates, chlorides, etc.) can be relatively fully dissolved in the water. The slurry has appropriate fluidity and viscosity, the filtration process can proceed smoothly, the filtration speed is moderate, the filter residue and the filtrate can be well separated, and the water content entrained in the filter residue is in a relatively suitable range. It not only ensures the good effect of washing and removing impurities but also does not overuse water resources, avoiding unnecessary waste, and at the same time, the amount of wastewater generated is also in a relatively reasonable range, not bringing too much pressure to the wastewater treatment link, achieving a better balance of resource utilization and cost control in the overall production process.In this embodiment, when the solid-liquid ratio is 1:5, the amount of water used is relatively sufficient, which can ensure that almost all soluble impurities are fully dissolved in water. From the perspective of impurity removal, it can make the manganese slag reach a very high purity, with minimal interference to the subsequent magnetization roasting and leaching processes, which is beneficial to improving the recovery efficiency of manganese and can provide a very high-quality raw material basis for the subsequent processes. However, due to the excessive amount of water, the difficulty of filtration separation increases significantly, the filtration time will be prolonged, and the moisture content entrained in the filter residue is relatively high, so more time and energy will be required for subsequent drying treatment. With a large amount of water used, there is a certain degree of water resource waste, and the amount of wastewater generated subsequently is also relatively large, which will bring a greater burden to the wastewater treatment link. Both the collection of wastewater, the operation of the treatment process, and the treatment cost will increase accordingly. Therefore, the selection of the solid-liquid ratio needs to be determined according to the actual situation.

[0060] In a preferred embodiment, in step A1, after mixing the manganese slag with water, stirring and washing are carried out in a stirring tank at a stirring speed of 100-200 r / min for a stirring time of 30-60 min. Within this stirring speed range, a water flow and vortex with appropriate intensity can be formed in the stirring tank. On the one hand, this water flow can continuously scour the surface of the manganese slag particles, breaking the adsorption layer formed by impurities on the particle surface, making it easier for impurities to detach from the manganese slag and enter the water. On the other hand, the vortex helps to accelerate the mixing of water and manganese slag, enabling the water to promptly carry away the dissolved impurities, maintaining the concentration gradient of impurities at the solid-liquid interface, and thus continuously promoting the dissolution process of impurities and improving the dissolution efficiency. If the stirring speed is too fast, exceeding 200 r / min, it may cause the liquid in the stirring tank to splash, resulting in material loss. At the same time, it will also increase the energy consumption and wear of the stirring equipment. Moreover, too high a stirring speed may cause overly violent collisions and frictions between the manganese slag particles, resulting in the fragmentation of some fine manganese slag particles and increasing the difficulty of subsequent filtration separation. If the stirring speed is lower than 100 r / min, the intensity of the water flow and vortex is insufficient, unable to fully drive the effective mixing of manganese slag and water, and the dissolution rate of impurities will be significantly slowed down, affecting the water washing effect and the overall production efficiency. It takes a certain amount of time for most soluble impurities to diffuse from the inside of the manganese slag particles to the surface and dissolve in water. The stirring time of 30-60 min can allow impurities to have enough time to complete the dissolution process, ensuring that most of the soluble impurities in the manganese slag can be removed. After this period of stirring, the dissolved amount of impurities basically reaches a relatively stable level, providing a relatively pure manganese slag raw material for the subsequent processes.

[0061] In a preferred embodiment, in step A2, the magnetizing agent is pulverized coal or coke powder; the auxiliary agent is sodium carbonate or calcium carbonate. Under the high-temperature conditions of magnetizing roasting, the carbon element in the pulverized coal or coke powder can react with the surrounding oxygen, consuming the oxygen in the roasting environment, thereby creating a relatively reducing atmosphere. In this reducing atmosphere, the insoluble manganese in the electrolytic manganese residue (such as high-valent manganese oxides) can obtain electrons and be reduced to magnetic low-valent manganese minerals, such as manganese ferrite spinel. This magnetic manganese mineral can be effectively separated by subsequent magnetic separation processes, greatly improving the recovery efficiency of manganese. The pulverized coal or coke powder will also undergo pyrolysis and other reactions at high temperatures, generating some active intermediate products. These intermediate products can interact with the minerals in the manganese residue, promoting the transformation and recombination of the mineral crystal structure, and converting the originally difficult-to-utilize insoluble manganese into an easily recoverable magnetic form. Sodium carbonate or calcium carbonate can act as a catalyst during the magnetizing roasting process, reducing the activation energy of the chemical reaction of converting insoluble manganese into magnetic manganese minerals. This means that the reaction can occur at a relatively lower temperature or in a shorter time, thus saving energy consumption and improving production efficiency. At the same time, it also reduces the damage to the equipment caused by high temperature and extends the service life of the equipment. The auxiliary agent can also chemically react with some components in the manganese residue, changing the crystal structure and physical properties of the minerals. For example, the gas generated by the decomposition of sodium carbonate or calcium carbonate at high temperatures can make the manganese residue particles more porous and loose, increasing the contact area between the manganese residue and the magnetizing agent, further promoting the magnetizing reaction and improving the magnetizing effect.

[0062] In a preferred embodiment, the addition amount of the magnetizing agent is 5%-15% of the mass of the manganese residue, and the addition amount of the auxiliary agent is 2%-5% of the mass of the manganese residue. When the addition amount of the magnetizing agent is within this range, it can provide a sufficient reducing atmosphere during the magnetizing roasting process. Under high-temperature conditions, the carbon element in the magnetizing agent reacts with oxygen to consume oxygen, making the roasting environment reducing, which helps to reduce insoluble manganese (such as high-valent manganese oxides) to magnetic low-valent manganese minerals, such as manganese ferrite spinel. If the addition amount is less than 5%, the provided reducing ability is insufficient, and the reduction reaction of insoluble manganese is incomplete, resulting in a decrease in the generation amount of magnetic manganese minerals and a reduction in the recovery efficiency of manganese. Within this addition amount range, the auxiliary agent can effectively reduce the activation energy of the magnetizing reaction and promote the conversion of insoluble manganese into magnetic manganese minerals. The auxiliary agent will undergo decomposition and other reactions at high temperatures, and the generated active substances can improve the physical and chemical properties of the manganese residue, making the reaction easier to proceed. When the addition amount is 2%-5%, it can just play its catalytic and promoting roles, improving the reaction rate and magnetizing effect.

[0063] Specifically, in Embodiment 3, the addition amount of the fixing agent is 3% of the mass of the manganese slag. Experiments are carried out with the addition amounts of the magnetizing agent being 0, 5%, 8%, 10%, 12%, and 15% of the mass of the manganese slag respectively. Each time, the same mass of the washed manganese slag is taken, and the magnetizing agent and the fixing agent are accurately weighed according to the set addition amounts, fully mixed with the manganese slag, then put into a roasting device of the same specification, and magnetizing roasting is carried out under the conditions of the same roasting temperature and the same roasting time. After roasting, it is cooled to room temperature, the material is added with water to be modulated into a pulp with a concentration of 25%, and then magnetic separation is carried out through a magnetic separation device, and relevant data is collected for subsequent analysis.

[0064] The experimental results are as follows:

[0065] When no magnetizing agent is added, due to the lack of additional reduction ability, the finally calculated manganese recovery efficiency is about 48.63%.

[0066] When the addition amount of the magnetizing agent is 5% of the mass of the manganese slag, due to the relatively weak reduction ability provided, the calculated manganese recovery efficiency is about 52.75%.

[0067] When the addition amount of the magnetizing agent increases to 8%, the reduction ability is enhanced, and the calculated manganese recovery efficiency is about 54.66%.

[0068] When the addition amount of the magnetizing agent reaches 10%, during the roasting process, the reduction reaction of insoluble manganese proceeds more fully, and the calculated manganese recovery efficiency is about 62.55%.

[0069] When the addition amount of the magnetizing agent is 12%, the reduction ability is further enhanced, and the amount of magnetic manganese minerals generated is relatively large. The calculated manganese recovery efficiency is about 63.93%.

[0070] When the addition amount of the magnetizing agent reaches 15%, the reducing gas is very strong, and the calculated manganese recovery efficiency is about 65.63%.

[0071] In Embodiment 4, the addition amount of the magnetizing agent is selected as 10% of the mass of the manganese slag (based on the discovery in the previous experiment that it is in a relatively appropriate addition amount range and is convenient for comparative observation). Experiments are carried out with the addition amounts of the fixing agent being 0, 2%, 3%, 4%, and 5% of the mass of the manganese slag respectively. Similarly, the same amount of the washed manganese slag is taken, the magnetizing agent and the fixing agent are added according to the set addition amounts, mixed evenly, then magnetizing roasting is carried out at the same roasting temperature and the same roasting time, and subsequent operations such as cooling, pulp modulation, and magnetic separation are carried out, and the corresponding data is collected for analysis. The experimental results are as follows:

[0072] When no fixing agent is added, the calculated manganese recovery efficiency is about 58.74%.

[0073] When the addition amount of the additive is 2% of the mass of the manganese slag, the additive can reduce the activation energy of the magnetization reaction to a certain extent, promote the conversion of insoluble manganese into magnetic manganese minerals, and the calculated manganese recovery efficiency is about 60.55%.

[0074] When the addition amount of the additive increases to 3%, its catalytic and promoting effects are enhanced, and the calculated manganese recovery efficiency is about 61.82%.

[0075] When the addition amount of the additive is 4%, its improvement effect on the reaction is further exerted, and the calculated manganese recovery efficiency is increased to about 43.68%.

[0076] When the addition amount of the additive reaches 5%, the manganese recovery efficiency can reach 65.06%.

[0077] During actual use, it is also necessary to measure the cost to select the appropriate magnetizing agent and the addition amount of the additive. Therefore, it will not be elaborated here.

[0078] In a preferred embodiment, in step A2, magnetization roasting is carried out in a rotary kiln or a muffle furnace, the roasting temperature is controlled at 600 - 800 °C, and the roasting time is 1 - 3 h. In the temperature range of 600 - 800 °C, the chemical reaction between the magnetizing agent (coal powder or coke powder) and insoluble manganese can proceed smoothly. This temperature range provides sufficient energy for the reaction, enabling insoluble manganese to undergo a reduction reaction with the magnetizing agent and be converted into magnetic manganese minerals. If the temperature is too low, the reaction rate is too slow, and the conversion of insoluble manganese is incomplete, which will reduce the manganese recovery efficiency; if the temperature is too high, it may cause other unnecessary phase changes or decomposition reactions of manganese minerals, affecting the formation of magnetic manganese minerals and the subsequent magnetic separation effect. Giving a roasting time of 1 - 3 h is to allow sufficient time for the reaction between insoluble manganese, the magnetizing agent, and the additive to complete. During this time period, the reaction proceeds step by step, and insoluble manganese is continuously converted into magnetic manganese minerals.

[0079] In a preferred embodiment, in step A2, the magnetic separation device includes a low-intensity magnetic separator and a high-intensity magnetic separator. Among them, the magnetic field intensity of the low-intensity magnetic separator is controlled at 100 - 300 mT, and the magnetic field intensity of the high-intensity magnetic separator is controlled at 800 - 1500 mT. When the material that has undergone magnetization roasting, cooling, and is modulated into a slurry with an appropriate concentration is transported to the magnetic separation stage, it first enters the low-intensity magnetic separator. The operator will, through an advanced magnetic field control system, accurately control the magnetic field intensity of the low-intensity magnetic separator within the specific range of 100 - 300 mT. In the separation chamber of the low-intensity magnetic separator, the slurry slowly flows under the combined influence of the magnetic field force and the water flow force. At this time, those minerals with relatively strong magnetism, such as possible iron minerals, etc., will be quickly adsorbed onto the magnetic medium of the magnetic separator under the action of the weak magnetic field, and are carried out of the slurry as the magnetic medium rotates, thus being preliminarily separated from other substances with weaker magnetism. The tailings after the preliminary separation by the low-intensity magnetic separator then enter the high-intensity magnetic separator. Similarly, the operator will carefully adjust the magnetic field parameters of the high-intensity magnetic separator to make the magnetic field intensity stable at 800 - 1500 mT. In the high magnetic field environment, the magnetic manganese minerals in the slurry will overcome the acting forces such as the water flow resistance and their own gravity, and be effectively adsorbed onto the surface of the magnetic medium of the high-intensity magnetic separator. Non-magnetic or minerals with extremely weak magnetism will be discharged as tailings along with the slurry flow. Thus, the further enrichment of the magnetic manganese minerals is achieved, providing high-grade raw materials for the subsequent chemical leaching process. During the entire magnetic separation process, the operator will continuously monitor parameters such as the magnetic field intensity and the slurry flow rate to ensure the stability and reliability of the magnetic separation effect.

[0080] In a preferred embodiment, in step A3, the anode of the electrolytic cell uses a lead-silver alloy plate, and the cathode uses a stainless steel plate; the lead-silver alloy plate has good electrical conductivity, which can enable the current to pass evenly through the anode during electrolysis, ensuring the smooth progress of the electrolysis reaction. At the same time, in the electrolytic environment, it has high chemical stability. In the reaction occurring at the anode, the lead-silver alloy plate can resist the corrosion of the electrolyte and will not easily dissolve or undergo other chemical reactions and be damaged. This ensures that the anode can maintain stable performance during the long-term electrolysis process, extends the service life of the anode, and reduces the frequent replacement and maintenance costs caused by anode damage. The stainless steel plate has good electrical conductivity, which can enable manganese ions to smoothly obtain electrons and be reduced to metallic manganese on the surface of the cathode. At the same time, it has high mechanical strength and hardness, can withstand various physical acting forces during electrolysis, and is not easily deformed or damaged. This ensures the stability of the cathode during electrolysis, enabling manganese to be evenly deposited on the surface of the cathode, which is conducive to obtaining metal manganese products with better quality.

[0081] In a preferred embodiment, during the electrolysis process, the cell voltage is controlled to be 3 - 5V, the current density is 300 - 500 A / m2, and the electrolysis temperature is 35 - 45 °C. At a cell voltage of 3 - 5V, while ensuring the smooth progress of the reaction, it is possible to avoid unnecessary side reactions caused by too high a voltage, such as the discharge of other impurity ions in the electrolyte, thereby improving the purity and electrolysis efficiency of manganese metal. The current density directly determines the deposition rate of manganese ions on the cathode. At a current density of 300 - 500 A / m, manganese ions can obtain electrons and deposit into metallic manganese on the cathode surface at an appropriate speed.

[0082] In a preferred embodiment, the magnetic separation device includes a weak magnetic separator and a strong magnetic separator. The weak magnetic separator and the strong magnetic separator have the same structure, hereinafter referred to as the magnetic separator, such as Figures 2 to 5As shown in the figure, the magnetic separator includes a housing 3, a feed chute 1, a discharge chute 5, a drum 6 and a drive mechanism; among them, the drum 6 is rotatably connected to the housing 3, and the feed chute 1 and the discharge chute 5 are arranged on both sides of the housing 3. An intermediate area 12, a magnetic separation area 14 and a blanking area 11 which are communicated with each other are arranged in the housing 3; among them, the magnetic separation area 14 is located at the top of the intermediate area 12, and the blanking area 11 is located between the magnetic separation area 14 and the intermediate area 12, and the magnetic separation area 14 in it is in contact with the drum 6. A feed port 8 is arranged at the bottom of the feed chute 1, and the feed chute 1 is communicated with the intermediate area 12 through the feed port 8. An intermediate port 13 is arranged between the intermediate area 12 and the magnetic separation area 14, and the intermediate area 12 and the magnetic separation area 14 are communicated through the intermediate port 13. A communication port 9 is arranged between the blanking area 11 and the magnetic separation area 14, and the blanking area 11 and the magnetic separation area 14 are communicated through the communication port 9. A discharge communication port 16 is arranged on one side of the discharge chute 5, and the discharge chute 5 is communicated with the magnetic separation area 14 through the discharge communication port 16, and the position of the discharge communication port 16 is higher than the position of the communication port 9. A blanking port 7 is arranged on one side of the bottom of the blanking area 11, and a discharge port 4 is arranged on one side of the bottom of the discharge chute 5. An installation shaft 19 is fixedly connected to the drum 6, the installation shaft 19 is rotatably connected to the housing 3, an installation frame 20 is rotatably connected to the installation shaft 19, and a magnet 15 is arranged at the bottom of the installation frame 20. The drive mechanism includes a first drive mechanism and a second drive mechanism. The first drive mechanism includes a drive motor 2 and a speed reducer. The drive motor 2 is connected to the installation shaft 19 through the speed reducer. The drive motor 2 is used to drive the installation shaft 19 to rotate, and the installation shaft 19 is used to drive the drum 6 to rotate. The second drive device includes an adjustment motor 21, a support frame 22, a reciprocating lead screw 24, a transmission slider 25, a transmission rack 26 and a transmission wheel 27; among them, the support frame 22 is fixedly connected to the housing 3, the adjustment motor 21 is fixedly connected to the housing 3, a limit rod 23 is fixedly connected to the support frame 22, the reciprocating lead screw 24 is rotatably connected to the support frame 22, the transmission slider 25 is threadedly connected to the reciprocating lead screw 24 and slidably connected to the limit rod 23, the transmission rack is fixedly connected to the transmission slider 25, the transmission wheel 27 is rotatably connected to the installation shaft 19 and connected to the installation frame 20, teeth are arranged on the outer side of the transmission wheel 27, and the transmission rack 26 meshes with the transmission wheel 27. Among them, the adjustment motor 21 is used to drive the reciprocating lead screw 24 to rotate, the reciprocating lead screw 24 is used to drive the transmission slider 25 to reciprocate, the transmission slider 25 will drive the transmission rack 26 to reciprocate when reciprocating, and the transmission rack 26 will drive the transmission wheel 27 to rotate forward and backward reciprocally during the reciprocating movement, further driving the installation frame 20 to swing reciprocally. This design helps to further separate magnetic minerals with weak magnetism or magnetic minerals wrapped by other substances from non-magnetic minerals. Because the reciprocating swing of the magnet 15 will cause the magnetic field strength and direction to change continuously within a certain range, the magnetic force received by the magnetic minerals in this changing magnetic field also changes continuously, so that it is easier to overcome the adhesion force, friction force, etc. between the magnetic minerals and non-magnetic minerals, realizing more accurate separation.Specifically, during use, the pulp enters the feeding tank 1 and flows into the middle area 12 through the feeding port 8. An additional water adding water pipe 10 is provided in the middle area 12. The water adding water pipe 10 is used for adding water and flushing water to prevent sedimentation in the middle area 12. The pulp in the middle area 12 enters the magnetic separation area 14 through the middle port 13 and gradually spreads upward. During this process, the rotating drum 6 cooperates with the magnet 15 to push the magnetic manganese ore towards the position of the discharge connection port 16. An additional flushing water pipe 17 is provided outside the discharge connection port 16. The flushing water pipe 17 is provided with a nozzle 18, and the nozzle 18 can spray water to wash down the manganese ore on the drum 6. In addition, it should be noted that when the manganese ore moves to the position of the discharge connection port 16, it is in a weak magnetic area, so it can be easily washed down. The manganese ore enters the discharge tank 5 through the discharge connection port 16 and finally is discharged from the discharge port 4 at the bottom of the discharge tank 5 for collection. As for the tailings that cannot be attracted by the magnet 15, they enter the blanking area 11 through the connection port 9 and finally are discharged from the blanking port 7 at the bottom of the blanking area 11. In this embodiment, the magnet 15 is reciprocally swung by the second driving mechanism to create a changing magnetic field environment, enabling those magnetic minerals that were originally difficult to be separated due to weak magnetism or being wrapped to have more opportunities to overcome external resistance and be successfully screened out from non-magnetic minerals, effectively avoiding the loss of this part of magnetic minerals, thus significantly improving the overall recovery rate of magnetic minerals, enabling more manganese ore resources to be recycled, and enhancing the economic benefits of the entire recovery process. Under the action of the changing magnetic field, magnetic minerals and non-magnetic minerals can be more accurately separated, reducing the possibility of non-magnetic minerals being mixed into the selected manganese ore products, resulting in a higher purity of the finally collected manganese ore products. The water adding water pipe 10 provided in the middle area 12 can timely supplement water to the middle area 12 and perform flushing operations according to actual conditions, keeping the pulp always in a suitable fluidity, effectively avoiding the problem of sedimentation of the pulp in the middle area 12 due to long-term residence or other reasons. This not only ensures that the pulp can smoothly enter the magnetic separation area 14 from the middle area 12, maintaining the continuity of the entire magnetic separation process, but also reduces the maintenance costs such as equipment blockage and cleaning caused by sedimentation, improving the operation stability and service life of the equipment. The rotation of the drum 6, the cooperation of the magnet 15, and the water spraying of the nozzle 18 of the flushing water pipe 17 together constitute an efficient magnetic separation system. The rotation of the drum 6 continuously stirs the pulp, enabling the magnetic minerals in the pulp to fully contact the magnet 15. The magnetic field generated by the magnet 15 exerts an adsorption effect, and the water spraying of the nozzle 18 can timely wash down the manganese ore adsorbed on the drum 6 to ensure its smooth entry into the discharge tank 5. The entire process cooperates with each other, making the magnetic separation process smoother and more efficient, further improving the efficiency and effect of magnetic separation, shortening the time of magnetic separation operation, and enhancing the overall production efficiency.

[0083] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inner", "front", "center", "both ends", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0084] In the present invention, unless otherwise clearly specified and defined, terms such as "installed", "set", "connected", "fixed", "swivelly connected", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. Unless otherwise clearly defined, for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0085] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for recovering insoluble manganese from electrolytic manganese residue, characterized in that: It includes the following steps: A1. Crush the electrolytic manganese slag and carry out fine grinding; mix the manganese slag with water and stir and wash it, and carry out solid-liquid separation through a filtering device; A2. Add a magnetizing agent and an auxiliary agent to the washed filter residue and mix evenly; magnetically roast the mixed material; cool the roasted material to room temperature, and then add water to prepare a slurry with a concentration of 20%-30%; pass the slurry through a magnetic separation device in sequence; A3. Use a 10%-20% sulfuric acid solution as a leaching agent, stir and leach the magnetic concentrate and the leaching agent in a reaction kettle, and the solid-liquid ratio is 1:3-1:5; separate the leaching solution and the leaching residue through a filtering device; add an oxidant to the leaching solution and adjust the pH value of the leaching solution to 4-5; concentrate the leaching solution and add ammonium sulfate to form an electrolyte solution, and send the electrolyte solution into an electrolytic cell for electrolysis; after the electrolysis is completed, obtain a metallic manganese product from the cathode plate.

2. A method for recovering insoluble manganese in electrolytic manganese residue according to claim 1, characterized in that: In step A1, a jaw crusher is used to crush the electrolytic manganese slag, and the manganese slag particles are controlled to be 5-10 mm; a ball mill is used to finely grind the electrolytic manganese slag, and the ball mill is used to reduce the particle size of the manganese slag to 0.044-0.074 mm.

3. A method for recovering insoluble manganese in electrolytic manganese residue according to claim 1, characterized in that: In step A1, the manganese slag and water are mixed according to a solid-liquid ratio of 1:3-1:

5.

4. A method for recovering insoluble manganese in electrolytic manganese residue according to claim 1, characterized in that: In step A1, after the manganese slag and water are mixed, they are stirred and washed in a stirring tank, the stirring speed is 100-200 r / min, and the stirring time is 30-60 min.

5. A method for recovering insoluble manganese in electrolytic manganese residue according to claim 1, characterized in that: In step A2, the magnetizing agent is pulverized coal or coke powder; the auxiliary agent is sodium carbonate or calcium carbonate.

6. A method for recovering insoluble manganese in electrolytic manganese residue according to claim 5, characterized in that: The addition amount of the magnetizing agent is 5%-15% of the mass of the manganese slag, and the addition amount of the auxiliary agent is 2%-5% of the mass of the manganese slag.

7. A method for recovering insoluble manganese in electrolytic manganese residue according to claim 1, characterized in that: In step A2, a rotary kiln or a muffle furnace is used for magnetic roasting, the roasting temperature is controlled at 600-800 °C, and the roasting time is 1-3 h.

8. A method for recovering insoluble manganese in electrolytic manganese residue according to claim 1, characterized in that: In step A2, the magnetic separation device includes a weak magnetic separator and a strong magnetic separator. Among them, the magnetic field intensity of the weak magnetic separator is controlled at 100-300 mT, and the magnetic field intensity of the strong magnetic separator is controlled at 800-1500 mT.

9. A method for recovering insoluble manganese in electrolytic manganese residue according to claim 1, characterized in that: In step A3, the anode of the electrolytic cell is made of a lead-silver alloy plate, and the cathode is made of a stainless steel plate.

10. A method for recovering insoluble manganese in electrolytic manganese residue according to claim 9, characterized in that: During the electrolysis process, the cell voltage is controlled at 3-5 V, the current density is 300-500 A / m2, and the electrolysis temperature is 35-45 °C.

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