System and method for directional co-production of high-purity manganese sulfate, manganese fluoride and potassium sulfate from blast furnace ferromanganese dust

Abstract

The application discloses a system and method for directional co-production of high-purity manganese sulfate, manganese fluoride and potassium sulfate from blast furnace ferromanganese dust, and the system comprises a reduction leaching unit, an extraction defluorination unit, a deimpurity unit, an extraction demanganese unit, an ammonia recovery and circulation unit and a purification and salt separation unit which are sequentially and serially arranged. According to the characteristics of impurities contained in blast furnace ferromanganese smelting dust washing wastewater, the valuable elements in the ash are extracted and preliminarily deimpurified through reduction leaching, high-value manganese fluoride and manganese sulfate are obtained through extraction defluorination and extraction demanganese recovery, deamination is realized through ammonia recovery, good saponification conditions are provided for manganese extraction, and good prerequisites are created for obtaining high-purity potassium sulfate and sodium chloride through pH adjustment, purification and salt separation. The application can improve the purity of target products at low cost without introducing impurities and causing secondary pollution, the whole process is free of wastewater and waste gas emission, the economic value is high, and the application meets the green and environment-friendly production requirements.

Description

Technical Field

[0001] This invention relates to the treatment of solid waste ash in the steel industry, specifically to a system for the targeted co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust, and a method for using this system to target the co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust. It belongs to the technical field of resource utilization treatment of blast furnace ferromanganese smelting dust in the steel industry. Background Technology

[0002] Ferromanganese is a ferroalloy material with a wide range of applications. Current production processes include the blast furnace method and the electric furnace method. The blast furnace method was the earliest developed and is still widely used in China. The blast furnace ferromanganese production process generates a large amount of dust, which mainly contains iron, manganese, fluorine, and alkali metals.

[0003] Currently, there is no specific technology for treating dust from blast furnace ferromanganese smelting. Some domestic steel plants use ferromanganese dust to produce cold-consolidated agglomerates and then reuse them in the furnace. Although this method is simple and low-cost, it leads to a decrease in the grade of the final ore, as well as the enrichment of fluoride and chloride ions, equipment corrosion, and nodule formation.

[0004] Currently, there are few reported technologies for the disposal of dust from ferromanganese smelting. Chinese patent CN105905925B, "A Method for Comprehensive Recovery of Valuable Metals from Dust and Residue from Ferromanganese Smelting," deals with dust from electric furnace ferromanganese smelting. The method involves water washing, followed by concentration and crystallization of the washing liquid to obtain potassium hydroxide. The washed residue is then leached with concentrated sulfuric acid, with an oxidant added to the leachate, pH adjusted, and a deweighting agent added. After fine filtration, concentration, crystallization, and drying, manganese sulfate is obtained. This process recovers potassium hydroxide, zinc slag, and manganese sulfate, employing a hydrometallurgical approach to recover multiple metals. However, this method treats dust generated from electric furnaces, whose composition differs from that of dust from blast furnace ferromanganese smelting. Studies have shown that blast furnace ferromanganese smelting dust contains large amounts of carbonates and fluoride ions, as well as high levels of sulfite ions in addition to sulfate ions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a system for the targeted co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust, and a method for utilizing this system to achieve the targeted co-production of these products from blast furnace ferromanganese dust. Targeting the characteristics of impurities in the washing wastewater from blast furnace ferromanganese smelting dust, the invention extracts valuable elements from the ash through reduction leaching, achieving preliminary impurity removal. Then, extraction defluorination removes fluorine and prepares high-value manganese fluoride. Further extraction demanganese removal, through the synergistic effect of forward and reverse extraction, yields high-value manganese sulfate. Furthermore, ammonia recovery provides saponification conditions for manganese extraction while simultaneously removing ammonia from the wastewater, creating favorable preconditions for pH adjustment purification and salt separation to obtain high-purity potassium sulfate and sodium chloride. This invention can improve the purity of each target product at low cost without introducing impurities or causing secondary pollution. The entire process generates no wastewater or waste gas emissions, resulting in high economic value and meeting green and environmentally friendly production requirements.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is specifically as follows:

[0007] According to a first embodiment of the present invention, a system for the directional co-production of high-purity manganese sulfate, manganese fluoride and potassium sulfate from blast furnace ferromanganese dust is provided.

[0008] A system for the directional co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust is disclosed. The system comprises a reduction leaching unit, an extraction defluorination unit, a purification unit, an extraction demanganese unit, an ammonia recovery and circulation unit, and a purification and salt separation unit, arranged in series. The reduction leaching unit has a dust conveying device connected to its inlet and a reduction leaching liquid conveying pipeline connected to its inlet. Its exhaust port is connected to the purification unit via a reduction exhaust pipeline. The exhaust port of the ammonia recovery and circulation unit is connected to the purification unit via an ammonia circulation pipeline. The salt outlet of the extraction defluorination unit is connected to a fluoride salt discharge device. The salt outlet of the extraction demanganese unit is connected to a manganese salt discharge device. The potassium salt outlet of the purification and salt separation unit is connected to a potassium salt discharge device, and its sodium salt outlet is connected to a sodium salt discharge device.

[0009] Preferably, the reduction leaching unit includes a reduction leaching tank and a leaching filter press arranged in series. The ash inlet of the reduction leaching tank is connected to a dust removal ash conveying device, its liquid inlet is connected to a reduction leaching liquid conveying pipeline, its exhaust port is connected to a reduction exhaust pipeline, and its discharge port is connected to the feed inlet of the leaching filter press via a conveying pipeline. The discharge port of the filter press is connected to the liquid inlet of the extraction defluorination unit via a conveying pipeline, and its filter cake outlet is connected to a filter cake conveying device.

[0010] Preferably, the extraction and defluorination unit includes a fluorine extraction tank and a fluorine-manganese precipitation tank connected in series. The inlet of the fluorine extraction tank is connected to the outlet of the filter press via a delivery pipe, its extract outlet is connected to the inlet of the fluorine-manganese precipitation tank via a delivery pipe, and its residual extract outlet is connected to the inlet of the impurity removal unit via a delivery pipe. A fluorine extractant addition pipe is connected to the inlet of the fluorine extraction tank. A manganese powder addition device is connected to the inlet of the fluorine-manganese precipitation tank, its salt outlet is connected to a fluoride salt delivery device, and its clear liquid outlet is connected to the inlet of the fluorine extraction tank via a fluorine extractant circulation pipe.

[0011] Preferably, the impurity removal unit includes an iron oxidation removal tank, a gravity and hardening removal tank, a saponification tank, and an impurity removal filter press connected in series. The inlet of the iron oxidation removal tank is connected to the extraction residue outlet of the fluorine extraction tank via a liquid delivery pipeline, and its outlet is connected to the inlet of the gravity and hardening removal tank via a liquid delivery pipeline. The air inlet of the gravity and hardening removal tank is connected to the reduction exhaust pipeline, and a sulfide addition device is connected to its dosing port. Its outlet is connected to the inlet of the saponification tank via a liquid delivery pipeline. The ammonia inlet of the saponification tank is connected to an ammonia circulation pipeline, and its outlet is connected to the inlet of the impurity removal filter press via a liquid delivery pipeline. The outlet of the impurity removal filter press is connected to the inlet of the extraction and manganese removal unit via a liquid delivery pipeline, and its sludge discharge outlet is connected to a sludge discharge device.

[0012] Preferably, the extraction and demanganese unit includes a manganese extraction tank, a back-extraction tank, and a crystallization device connected in series. The inlet of the manganese extraction tank is connected to the outlet of the impurity removal and filtration device via a delivery pipeline. A manganese extractant addition pipeline is connected to its inlet. The extractant outlet is connected to the inlet of the back-extraction tank via a delivery pipeline, and the residual extract outlet is connected to the inlet of the ammonia recovery and circulation unit via a delivery pipeline. The back-extraction tank has a back-extraction liquid addition pipeline connected to its inlet. The back-extraction liquid outlet is connected to the inlet of the crystallization device via a delivery pipeline, and the residual back-extraction liquid outlet is connected to the inlet of the manganese extraction tank via a manganese extractant circulation pipeline. The salt outlet of the crystallization device is connected to a manganese salt delivery device.

[0013] Preferably, the ammonia recovery and circulation unit includes an alkali conditioning tank and an ammonia stripping tower connected in series. The inlet of the alkali conditioning tank is connected to the outlet of the extraction residue from the manganese extraction tank, and a liquid alkali addition pipe is connected to its dosing port. Its outlet is connected to the inlet of the ammonia stripping tower via a delivery pipe. The ammonia outlet of the ammonia stripping tower is connected to the ammonia circulation delivery pipe, and its outlet is connected to the inlet of the purification and salt separation unit.

[0014] Preferably, the purification and salt separation unit includes an oxidative desulfurization tank, a pH adjustment tank, and an evaporative salt separation device connected in series. The inlet of the oxidative desulfurization tank is connected to the outlet of the ammonia stripping tower via a pipeline, and its outlet is connected to the inlet of the pH adjustment tank via a pipeline. A sodium hypochlorite addition device is connected to the pH adjustment tank's dosing port. The inlet of the pH adjustment tank is also directly connected to the outlet of the ammonia stripping tower via a pipeline, and its outlet is connected to the inlet of the evaporative salt separation device via a pipeline. A dilute sulfuric acid addition pipeline is connected to the pH adjustment tank's acid addition port. The potassium salt outlet of the evaporative salt separation device is connected to a potassium salt discharge device, and its sodium salt outlet is connected to a sodium salt discharge device.

[0015] Preferably, the system also includes a pretreatment unit, which comprises a three-stage countercurrent washing device, a two-stage flotation device, a transition degradation tank, a mixed salt sedimentation tank, a redox tank, and a homogenizing sedimentation tank. The ash inlet of the three-stage countercurrent washing device is connected to a dust collection ash conveying device, its water inlet is connected to an industrial water conveying pipeline, its slag outlet is connected to the feed inlet of the two-stage flotation device via a slag conveying mechanism, and its liquid outlet is connected to the liquid inlet of the mixed salt sedimentation tank via a liquid conveying pipeline. The slag outlet of the two-stage flotation device is connected to the feed inlet of the reduction leaching tank via a slag conveying mechanism, and its liquid outlet is connected to the liquid inlet of the transition degradation tank via a liquid conveying pipeline. The chemical dosing port of the transition degradation tank is connected to a degradation agent addition mechanism, and its liquid outlet is connected to the liquid inlet of the redox tank via a liquid conveying pipeline. The mixed salt sedimentation tank has a carbon dioxide inlet pipe connected to its air inlet. Its mixed salt outlet is connected to the inlet of the fluoride extraction tank via a mixed salt conveying mechanism, and its outlet is connected to the inlet of the oxidation-reduction tank via a liquid conveying pipe. The oxidation-reduction tank has an oxidizing and reducing agent addition mechanism connected to its dosing port, and its outlet is connected to the inlet of the homogenizing sedimentation tank via a liquid conveying pipe. The homogenizing sedimentation tank's inlet is also connected to the extraction residue outlet of the manganese extraction tank via a liquid conveying pipe, and its outlet is connected to the inlet of the alkali adjustment tank via a liquid conveying pipe.

[0016] Preferably, the transition degradation tank is also equipped with a salt concentration detection device, and its discharge port is connected to the inlet of the two flotation units via a liquid delivery pipeline. The exhaust port of the pH adjustment tank is connected to the carbon dioxide inlet pipeline via a gas delivery pipeline.

[0017] Preferably, pH probes are installed in the alkali adjustment tank, pH adjustment tank, and homogenization sedimentation tank.

[0018] According to a second embodiment of the present invention, a method for the directional co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust is provided.

[0019] A method for the directional co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust, or a method using the system described in the first embodiment, comprising the following steps:

[0020] 1) Reduction leaching: Sulfuric acid and ferrous sulfate are used as leaching agents to leach blast furnace ferromanganese dust, and the leachate is obtained after solid-liquid separation. The gas generated during the leaching process is sent to step 3) to participate in the heavy and hard removal treatment.

[0021] 2) Defluorination: The leaching solution is extracted using a fluorine extractant to obtain a fluorine-containing extract and a defluorinated residue. Manganese powder is added to the fluorine-containing extract to prepare high-purity manganese fluoride. The defluorinated residue proceeds to the next step.

[0022] 3) Impurity removal: First, an oxidant is used to oxidize and remove iron from the defluorination residue, then sulfides are added for heavy and hard removal, and then ammonia is added for saponification. After solid-liquid separation, the defluorination residue is obtained.

[0023] 4) Manganese Extraction: The defluorination residue is extracted using a manganese extractant to obtain a manganese-containing extract and a manganese extraction residue. Dilute sulfuric acid is added to the manganese-containing extract for back-extraction, and the back-extraction solution is evaporated and crystallized to obtain high-purity manganese sulfate. The back-extraction residue is recycled as a manganese extractant, while the manganese extraction residue proceeds to the next process.

[0024] 5) Ammonia nitrogen removal: First, adjust the residual manganese extraction liquid to a strongly alkaline state and send it to the ammonia removal unit for ammonia removal treatment to obtain ammonia-removed wastewater. The removed ammonia nitrogen is recycled in the form of ammonia water to participate in the saponification treatment in step 3).

[0025] 6) Purification and salt separation: First, sodium hypochlorite solution is used to oxidize the ammonia removal wastewater, then acid is added to restore the wastewater to neutral, and finally, high-purity potassium sulfate and sodium chloride are obtained by temperature-variable evaporation and salt separation.

[0026] Preferably, in step 1), the mass concentration of the sulfuric acid is 0.5-3 mol / L, more preferably 1-1.5 mol / L. The mass of the ferrous sulfate solid is 30-60% of the mass of the blast furnace ferromanganese dust, more preferably 40-50%.

[0027] Preferably, in step 1), the volume-to-mass ratio of sulfuric acid to ferrous sulfate in the leaching agent is 1.5-4:1, more preferably 2-3.5:1.

[0028] Preferably, the volume-to-mass ratio of the leaching agent to the blast furnace ferromanganese dust is 0.8-2.5:1, and more preferably 1-2:1.

[0029] Preferably, in step 2), the fluorine extractant is tertiary amine N235 (trioctyldecyl tertiary amine), and its amount is 2-6 times the total volume of the extract, preferably 3-5 times. The extraction time is 5-25 min, preferably 10-20 min.

[0030] Preferably, in step 3), the iron removal by oxidation is performed using hydrogen peroxide or ozone (preferably hydrogen peroxide), with an addition amount of 0.3-6% of the mass of the defluorination residue, preferably 0.5-4%. The removal of heavy metals and hardness is performed by sulfidation precipitation using one or more of barium sulfide, sodium sulfide, and hydrogen sulfide (preferably sodium sulfide), with an addition amount of 0.2-0.7% of the mass of the defluorination residue, preferably 0.4-0.7%. The saponification treatment involves adjusting the pH of the defluorination residue to 3.5-5.5 using ammonia, preferably 4-5.

[0031] Preferably, in step 4), the manganese extractant is a mixed extractant (V:V, volume ratio) consisting of 30-50% di-(2-ethylhexyl)phosphonic acid P229 and 50-70% sulfonated kerosene. The extraction ratio (O / A) is 1-4:1, preferably 2-3:1. The extraction time is 5-20 min, preferably 8-15 min.

[0032] Preferably, in step 4), the back-extraction is a multi-stage countercurrent back-extraction, preferably 2-3 stages. The concentration of the dilute sulfuric acid is 10-30%, preferably 15-25%. The extraction ratio (O / A) for each stage is 1:2-4, preferably 1:2-3. The back-extraction time for each stage is 8-20 min, preferably 10-15 min.

[0033] Preferably, in step 5), adjusting the residual manganese extraction solution to a strongly alkaline state involves adjusting the pH of the residual manganese extraction solution to 10-14 using liquid alkali, preferably 11-12. The ammonia removal device is a stripping tower or an ammonia stripping tower, preferably an ammonia stripping tower.

[0034] Preferably, in step 6), the mass concentration of the sodium hypochlorite solution is 0.5-3%, preferably 0.8-2%; and the amount added is 0.01-2% of the wastewater mass, preferably 0.05-1.5%. Adding acid to neutralize the wastewater specifically involves adding dilute sulfuric acid to neutralize the wastewater to a pH of 6-7.5, preferably 6.5-7.

[0035] Preferably, the method further includes the following preprocessing steps:

[0036] i) Ash washing: Industrial water is used to wash and leach the dust from blast furnace ferromanganese smelting to obtain washing slag and ash washing wastewater. Carbon dioxide is introduced into the ash washing wastewater to carry out a carbonation reaction. After solid-liquid separation, mixed salt and desalination wastewater are obtained. The mixed salt is combined with the leachate from step 1) and then proceeded to step 2). The washing slag enters step ii), and the desalination wastewater enters step iii).

[0037] ii) Flotation: The washed residue obtained in step i) is subjected to two-stage flotation to recover carbon powder and fluorite, respectively, yielding flotation residue and flotation water. Low-salt flotation water with a salt content below the set salt concentration is recycled for flotation of the washed residue. High-salt flotation water with a salt content above the set salt concentration undergoes COD degradation treatment before entering the wastewater pretreatment process. The flotation residue is then subjected to reduction leaching in step 1).

[0038] iii) Oxidation-reduction: The desalination wastewater obtained in step i) is mixed with the high-salt flotation water after COD degradation obtained in step ii) to obtain mixed wastewater. Potassium permanganate solution is added to the mixed wastewater for oxidation treatment, followed by ferrous salt solution for reduction treatment. Finally, the reduced wastewater and manganese extraction residue are homogenized. The homogenized wastewater enters step 5) for ammonia nitrogen removal. Notably, the wastewater after ammonia nitrogen removal is not oxidized but directly mixed with acid to neutralize the wastewater. The carbon dioxide generated during homogenization and neutralization is recycled back to step i) to participate in the carbonation reaction.

[0039] Preferably, in step i), the water washing and leaching is a three-stage countercurrent water washing. The water-to-ash ratio during water washing is 1-8:1, preferably 2-6:1.

[0040] Preferably, in step ii), the flotation agent used for recovering carbon powder by flotation is kerosene, and the amount added is 0.1-0.8% of the raw material mass, preferably 0.2-0.5%.

[0041] Preferably, in step ii), the collector used for flotation recovery of fluorite is one of oleic acid, oxidized paraffin soap (731), CM-10, or No. 2 oil, with a dosage of 550-1100 g / t, preferably 600-900 g / t. The pH adjuster is sodium carbonate, with the pH value adjusted to 8-10, preferably 9-10. The inhibitor is water glass, with a dosage of 1600-2500 g / t, preferably 1800-2200 g / t.

[0042] Preferably, in step ii), the salt concentration is set to 80-120 g / L, more preferably 90-110 g / L.

[0043] Preferably, in step ii), the COD degradation treatment specifically involves oxidative degradation using hydrogen peroxide or Fenton's reagent.

[0044] Preferably, in step iii), the concentration of the potassium permanganate solution is 15-40%, more preferably 20-30%. The amount added is 2-10% of the total mass of the wastewater, more preferably 3-8%. The oxidation treatment time is 5-50 min, more preferably 10-30 min.

[0045] Preferably, in step iii), the concentration of the ferrous salt solution is 10-30%, more preferably 15-25%. The amount added is 3-10% of the total mass of the wastewater, more preferably 4-8%. The reduction treatment time is 5-50 min, more preferably 10-30 min.

[0046] Preferably, in step iii), the ferrous salt is ferrous sulfate and / or ferrous chloride, with ferrous sulfate being the most preferred.

[0047] Preferably, in step iii), the pH of the homogenized wastewater is 6-8.5, and more preferably 7-8.

[0048] Preferably, the dust from the blast furnace ferromanganese smelting is dust containing iron, manganese, fluorine, alkali metals, carbonate and sulfite generated during ferromanganese smelting using the blast furnace method.

[0049] In existing technologies, the dust generated during blast furnace ferromanganese smelting is complex in composition. Direct discharge of this dust pollutes the environment and wastes valuable resources. However, current treatment methods for this dust are unsatisfactory, lacking a complete processing technology. Achieving efficient resource utilization of blast furnace ferromanganese smelting dust has long been a major challenge for researchers in this field.

[0050] In this invention, in the reduction leaching unit, dilute sulfuric acid and ferrous sulfate are used as leaching agents to reduce and leach dust from blast furnace ferromanganese smelting. Ferromanganese ions in the ash are leached out in the form of manganese sulfate and ferric sulfate. Thiosulfate ions in the ash are acidified and decomposed into elemental sulfur and sulfur dioxide. Elemental sulfur is adsorbed by carbon powder in the ash, while sulfur dioxide is released with the gas. Carbonates in the ash decompose, producing a large amount of carbon dioxide, which is then released. Most of the remaining calcium ions in the slag react with sulfate ions in the leaching agent to form calcium sulfate precipitate. Additionally, the remaining fluoride ions in the slag are also leached into the liquid phase. After leaching, carbon powder and calcium sulfate are recovered by pressure filtration. The clarified leaching solution is used for subsequent recovery to prepare high-purity manganese sulfate, manganese fluoride, and potassium sulfate. Through reduction leaching, valuable elements in the dust from blast furnace ferromanganese smelting are extracted, achieving a preliminary impurity removal effect.

[0051] In this invention, the fluoride ion concentration in the leachate obtained from a typical reduction leaching unit in the extraction and defluorination unit can reach approximately 3 g / L. If not removed, this can easily affect the quality of the subsequently generated potassium and sodium salt products. Therefore, an extraction method is used to remove fluoride and generate high-value manganese fluoride products. This process simultaneously removes fluoride ions and prepares new manganese fluoride products, achieving the goal of turning waste into treasure. A fluoride-containing extraction solution is obtained by using tertiary amine N235 as the fluoride extractant. Manganese powder is then added to the obtained fluoride-containing extraction solution, causing the fluoride to precipitate as manganese fluoride, thus achieving the recovery of high-purity manganese fluoride. The solution after recovering the manganese fluoride can be mixed with the fluoride extractant and recycled.

[0052] In this invention, the wastewater after fluoride ion removal contains numerous impurities, such as iron, magnesium, calcium, and zinc. Therefore, this invention removes these impurities through oxidation iron removal tanks, heavy metal removal and hardening removal tanks, and saponification tanks within the impurity removal unit. This ensures the high quality of the subsequently recovered potassium and sodium salts. Specifically, hydrogen peroxide or ozone is added to the defluorination wastewater to oxidize it, causing ferrous iron to precipitate as ferric iron. Then, a certain amount of sulfides, such as barium sulfide or sodium sulfide, is added to convert heavy metals (zinc) in the wastewater into sulfide precipitates. Simultaneously, carbon dioxide generated during the reduction leaching process is introduced to remove calcium and magnesium hardness from the wastewater. During this process, a reaction occurs where sulfides react with sulfur dioxide to form thiosulfate ions. After the reaction, the pH of the solution is adjusted to approximately 4-5 using ammonia water, providing saponification conditions for manganese extraction. The crystallized clear liquid can be recycled and mixed with the manganese extractant for manganese extraction.

[0053] In this invention, manganese ions are removed from the wastewater solution after impurity removal treatment through forward manganese extraction and multi-stage back-extraction in the extraction and manganese removal unit to obtain high-purity manganese sulfate product. In the manganese extraction tank, a mixed extractant consisting of carboxylic acids, phosphoric acids, and kerosene diluent is used to extract manganese. The resulting manganese ion-containing solution is then back-extracted in the back-extraction tank using dilute sulfuric acid as the back-extraction agent. The resulting manganese sulfate-containing solution is then evaporated and crystallized to recover high-purity manganese sulfate.

[0054] In this invention, the solution after manganese extraction mainly contains ammonia nitrogen, potassium, sodium, sulfate, thiosulfate, chloride, and carbonate. Liquid alkali is used in the alkali adjustment tank to adjust the pH to 11-12, making the ammonia nitrogen in the wastewater volatile. The highly alkaline wastewater is then introduced into a stripping tower or ammonia stripping tower to remove the ammonia nitrogen. The removed ammonia nitrogen is recovered as ammonia water and used as the source of ammonia water for the saponification reaction in the manganese extraction process, thus achieving ammonia recycling within the system. This achieves zero ammonia nitrogen discharge and completes the removal of ammonia nitrogen from the wastewater, laying a solid foundation for the subsequent preparation of high-purity potassium sulfate products.

[0055] In this invention, sodium hypochlorite is added to the wastewater after ammonia nitrogen removal in the purification and salt separation unit. This is primarily used to oxidize the thiosulfate ions formed in the wastewater, converting them into sulfate ions. At this stage, the wastewater still contains carbonate, sulfate, and chloride ions, forming a five-element phase diagram, making salt separation difficult. Therefore, a further pH adjustment tank is used to add dilute sulfuric acid to adjust the solution, mainly to achieve deep removal of carbonate and thiosulfate ions. Finally, in the evaporation and salt separation device, high-value potassium sulfate and sodium chloride products are obtained through temperature-variable evaporation separation and recovery, achieving zero wastewater discharge and resource utilization.

[0056] In this invention, the method for the targeted co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese smelting dust generally follows this process: Step 1: Reduction leaching of blast furnace ferromanganese smelting dust: Using dilute sulfuric acid and ferrous sulfate solution as leaching agents, the blast furnace ferromanganese smelting dust is leached under acidic conditions. The generated gases (mainly carbon dioxide and carbon dioxide) are passed into subsequent wastewater for treatment to avoid environmental pollution from waste gas emissions. The generated solids (mainly carbon powder and calcium sulfate) are transported off-site for disposal (for the recovery of carbon powder and calcium sulfate products), yielding a leachate for subsequent resource recovery. Step 2: Recovery of high-purity manganese fluoride from the leachate: The leachate obtained in Step 1 enters a fluorine extraction device for fluoride extraction and recovery. The obtained fluorine extract is then mixed with manganese powder to recover high-purity manganese fluoride. Step 3: Purification of the Residual Fluoride Solution: The residual fluoride solution is first oxidized to remove iron by adding an oxidant. Then, a certain amount of sodium sulfide is added to the solution, along with the gas generated during the leaching process in Step 1 (carbon dioxide reacts with calcium and magnesium in the wastewater to precipitate, reducing wastewater hardness; sulfides react with sulfur dioxide to form thiosulfate ions, achieving sulfur dioxide elimination). A certain amount of ammonia is then introduced to adjust the wastewater pH (pH 4-5, providing saponification conditions for subsequent manganese extraction). After unified solid-liquid separation, the solids are transported off-site for disposal, while the clarified liquid enters the subsequent process. Step 4: High-Purity Manganese Sulfate Recovery: The solution obtained in Step 3 enters a manganese extraction unit for manganese ion extraction. The resulting manganese extract is back-extracted with dilute sulfuric acid and then evaporated and crystallized to recover high-purity manganese sulfate. The remaining manganese extraction liquid enters the subsequent wastewater treatment system. Step 5: Ammonia Resource Recycling: After treatment in Step 4, liquid alkali is added to adjust the pH value to 11-12. Then, the wastewater enters an ammonia stripping tower or ammonia stripping unit for ammonia nitrogen removal. The removed ammonia nitrogen is recovered as ammonia water and returned to Step 3 for recycling. The wastewater after ammonia removal enters the subsequent treatment unit. Step 6: High-Purity Potassium Sulfate Recovery: Sodium hypochlorite is added to the wastewater after treatment in Step 5 for oxidation (oxidizing the thiosulfate ions formed in the wastewater). Then, dilute sulfuric acid is added to adjust the pH value to about 6-7 (the wastewater also contains carbonate, sulfate, and chloride ions, forming a five-element phase diagram, making salt separation difficult). The wastewater then enters an evaporation concentration and salt separation system for variable-temperature evaporation to recover potassium sulfate and sodium chloride.

[0057] In this invention, the process also includes a pretreatment step, and the entire process flow is as follows: Step 1: Blast furnace ferromanganese smelting dust washing: The dust from blast furnace ferromanganese smelting is fed into a three-stage countercurrent washing system for washing, resulting in washed slag and leaching wastewater. Step 2: Washed slag flotation recovery of carbon powder and fluorite: The washed slag obtained in Step 1 is fed into a first-stage flotation reactor to float carbon powder, and then into a second-stage flotation reactor to float fluorite, finally obtaining flotation slag and flotation water; the flotation water is preferentially recycled. When the salt concentration is high, it enters a COD degradation reaction tank, where hydrogen peroxide or Fenton's reagent is added for oxidation, and then it is treated together with the leaching wastewater from Step 1. Step 3: Carbon dioxide recycling and desalination: Recovered carbon dioxide is introduced into the leaching wastewater obtained in Step 1. The carbon dioxide originates from the carbon dioxide generated during the pH adjustment process in the subsequent step. Then, mixed salt is obtained through precipitation separation for subsequent use. The clarified solution is tested for fluoride ion concentration. Generally, when the fluoride ion concentration is below 500 mg / L, it can proceed to the subsequent reaction device. Step 4: Pre-oxidation coupled with reduction to remove impurities from the washing wastewater: The wastewater obtained in Step 3 enters the oxidation reaction tank, and then potassium permanganate solution is added for oxidation treatment; the oxidized wastewater enters the reduction reaction tank, and ferrous salt solution is added for reduction. Step 5: Reduction leaching of flotation residue: Using dilute sulfuric acid and ferrous sulfate solution as leaching agents, the flotation residue obtained in Step 2 is leached under acidic conditions to obtain flotation residue leachate and residual calcium sulfate. Step Six: Recovery of High-Purity Manganese Sulfate from Leachate: The flotation residue leachate obtained in Step Five and the mixed salt obtained in Step Three are subjected to hardness removal and fluoride dissolution. The filtered and separated solution enters the fluoride extraction unit for fluoride extraction and recovery. The obtained fluoride extract is then mixed with manganese powder to recover manganese fluoride. The fluoride extraction residue is then subjected to oxidation to remove iron, sulfidation to remove heavy metals, and ammonia saponification before entering the manganese extraction unit for manganese ion extraction. The obtained manganese extract is then back-extracted with dilute sulfuric acid and evaporated and crystallized to recover high-purity manganese sulfate. The manganese extraction residue is then sent to the homogenization and equalization tank of the wastewater treatment system. Step Seven: Low-Cost Wastewater and Leachate Co-Purification Technology. The alkaline water washing leaching wastewater and the acidic manganese extraction residue wastewater are homogenized and pH-adjusted to allow the pollutants in the two wastewater streams to interact and synergistically remove pollutants, reducing wastewater treatment costs. Step Eight: Ammonia Recycling Technology. The extraction of manganese sulfate from the leachate requires ammonia saponification, which generates ammonia nitrogen wastewater. By adjusting the alkali of the ammonia nitrogen wastewater, ammonia resources are recovered synergistically, achieving ammonia nitrogen recycling within the system. Step 9: Wastewater conditioning and recovery of potassium sulfate and sodium chloride: The supernatant obtained in step 8 enters the pH adjustment tank, where dilute sulfuric acid is added to adjust the pH value to about 6-7. Then it enters the salt separation system for variable temperature evaporation to recover potassium sulfate and sodium chloride.

[0058] In this invention, industrial water and manganese-iron ash are mixed and stirred in a certain proportion (water-ash ratio 1-7:1). After thorough washing, the easily soluble substances in the manganese-iron ash enter the water. The filter residue is returned to sintering or transported for disposal. The resulting wastewater is strongly alkaline, with a pH > 11. Its cations mainly include iron, manganese, potassium, sodium, and zinc, while its anions mainly include carbonate, sulfite, sulfate, chloride, fluoride, and hydroxide ions.

[0059] In this invention, the dust from blast furnace ferromanganese smelting contains a significant amount of carbon powder and fluorite. These two substances do not leach into the aqueous phase and possess good recovery value, allowing for recovery via flotation. However, there is a risk that the fluorite may dissolve during subsequent acidic leaching, leading to an increase in fluoride ions in the leachate. Carbon powder and fluorite are recovered through a two-stage flotation process. Kerosene is used as a recoverant to achieve carbon powder separation; oleic acid, 731, CM-10, or No. 2 oil is used as a recoverant, sodium carbonate as a pH adjuster, and water glass as a depressant to achieve fluorite separation.

[0060] In this invention, because the wastewater contains a large amount of carbonate ions, a large amount of carbon dioxide is generated during the pH adjustment process. The released carbon dioxide is returned to the washing stage, where it undergoes a carbonation reaction with potassium carbonate and sodium hydroxide in the washing solution, converting potassium carbonate into potassium bicarbonate, which has lower solubility and precipitates out. Furthermore, as the concentration of potassium carbonate in the solution increases (due to the continuous enrichment of potassium ions through circulating washing and leaching), a common ion effect occurs, causing potassium fluoride in the solution to precipitate. The precipitated potassium bicarbonate and potassium fluoride are discharged from the system, thus reducing impurities and salt content at the wastewater source. Potassium bicarbonate can be used as an alkali adjuster in saponification reactions with ammonia.

[0061] In this invention, analysis shows that the leaching wastewater contains a large amount of sulfite ions, which, if not removed, will reduce the purity of the recovered potassium sulfate. Strong oxidizing potassium permanganate is used to oxidize it to sulfate ions. The potassium introduced by the potassium permanganate will not affect the water quality, and the introduced manganese will be removed in subsequent processes. Furthermore, the oxidation process can be combined with the flotation water to remove COD. Studies have shown that the leaching wastewater contains high-valence manganese and iron, which can exist stably in highly alkaline solutions. Reducing ferrous salts are used to reduce the high-valence manganese and iron ions to divalent manganese ions and trivalent iron ions, and then the high alkalinity of the wastewater is utilized to achieve deep purification of manganese and iron in the wastewater. It should be noted that when the system or process of this invention has a pretreatment unit or process, the wastewater after treatment by the ammonia recovery recycling unit or after the ammonia nitrogen removal process does not need to undergo a sodium hypochlorite oxidation step; the pH can be directly adjusted to neutral to facilitate temperature-dependent salt separation.

[0062] In this invention, dilute sulfuric acid and ferrous sulfate are used as leaching agents to reductively leach the flotation residue. The manganese and ferric ions in the residue are leached out as manganese sulfate and ferric sulfate, respectively. Most of the remaining calcium ions in the residue react with sulfate ions in the leaching agent to form calcium sulfate precipitate. Additionally, the remaining fluoride ions in the residue are also leached into the liquid phase. Because of the two-stage treatment of water washing and flotation, the concentration of fluoride ions in the leachate will not be too high, which helps to reduce corrosion of the leaching tank.

[0063] In this invention, the pH of the flotation residue leachate is generally around 2-3, and in addition to manganese sulfate, it mainly contains fluoride ions, calcium, magnesium, iron, aluminum, zinc, etc. First, potassium bicarbonate and potassium fluoride recovered from the carbonation of the wastewater are co-mixed with the leachate, and the pH of the solution is adjusted using potassium bicarbonate. Simultaneously, potassium fluoride dissolves into the leachate and is subsequently recycled. Then, fluoride removal is performed using an extraction method, with tertiary amine N235 as the extractant to obtain a fluoride ion solution. Manganese powder is added to the fluoride extract to precipitate manganese fluoride. Next, the wastewater after extraction is oxidized by adding hydrogen peroxide or ozone, causing the ferrous iron in the wastewater to precipitate as ferric iron. At the same time, a certain amount of sulfides, such as barium sulfide or sodium sulfide, is added to precipitate the heavy metals in the wastewater as sulfide precipitates. Finally, ammonia water is added to the wastewater after metal ion removal to adjust the pH of the solution to 4-5. At the same time, carboxylic acid and phosphoric acid extractants and kerosene diluent are added to extract manganese. The manganese extract is then back-extracted with dilute sulfuric acid. The resulting solution is then evaporated and crystallized to recover high-purity manganese sulfate.

[0064] In this invention, the washing wastewater after carbonation and redox treatment is alkaline and contains not only sulfate, potassium, sodium, and carbonate ions that can be recycled, but also a high concentration of zinc ions. The leaching wastewater after manganese extraction is acidic and contains a certain concentration of calcium, magnesium, aluminum, and zinc ions. By mixing these two wastewater streams and adjusting the pH of the resulting solution to 6-8, zinc and aluminum ions precipitate under these pH conditions during mixing, while calcium and magnesium ions react with carbonate ions in the wastewater and are removed.

[0065] In this invention, after homogenization, the wastewater undergoes initial sedimentation and solid-liquid separation. The pH value is then adjusted to 11-12 using liquid alkali, making the ammonia nitrogen in the wastewater volatile. The wastewater is then introduced into a stripping tower or ammonia stripping tower to remove the ammonia nitrogen. The removed ammonia nitrogen is recovered as ammonia water and used as the source of ammonia water for the saponification reaction in the manganese extraction process, thus realizing the circulation of ammonia in the system.

[0066] In this invention, after salt purification and impurity removal, the leaching wastewater contains carbonate, sulfate, and chloride ions, forming a five-element phase diagram, making salt separation difficult. During pH adjustment, dilute sulfuric acid is added to acidify the carbonate ions. This converts the anions in the wastewater into sulfate and chloride ions, reducing the difficulty of evaporation and salt separation.

[0067] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0068] 1. The system of the present invention targets the characteristics of dust from blast furnace ferromanganese smelting. It extracts and enriches valuable elements in the ash through a reduction leaching unit, which plays a preliminary role in removing impurities. Then, through the synergistic coupling of an extraction defluorination unit, an impurity removal unit, an extraction demanganese unit, an ammonia recovery and recycling unit, and a purification and salt separation unit, high-value manganese fluoride, manganese sulfate, potassium sulfate, and sodium chloride products are recovered respectively. At the same time, the wastewater and waste gas generated inside the system can be digested internally, achieving a technical effect of 1+1 greater than 2.

[0069] 2: The method of this invention is based on the characteristics of dust from blast furnace ferromanganese smelting. It is the first to propose a technical concept of using water washing to recover high-purity manganese sulfate, manganese fluoride, potassium sulfate, and sodium chloride from dust from blast furnace ferromanganese smelting. By combining reduction leaching, defluorination, heavy metal removal, hardening removal, manganese removal, ammonia nitrogen removal, temperature-controlled salt separation, and pretreatment such as water washing, flotation, oxidation, reduction, salt precipitation, and sedimentation, the wastewater is purified and impurities are removed in stages. This maximizes the removal of impurities and turns waste into treasure by recovering high-value byproducts.

[0070] 3. This invention is specifically designed based on the water quality of leaching wastewater. It can remove key pollutants that affect the quality of by-products at low cost without introducing impurities or causing secondary pollution. At the same time, it optimizes the separation and precipitation process of heavy metals such as carbonate, sulfate, fluoride, and high-valence iron and manganese, simplifies the complex multi-phase diagram, greatly reduces the difficulty of salt separation, recovers a variety of high-value salt products, and achieves zero emissions of wastewater and exhaust gas. Attached Figure Description

[0071] Figure 1 This is a simplified structural diagram of the system for the directional co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust according to the present invention.

[0072] Figure 2 This is a schematic diagram of the overall structure of the system for the directional co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust of the present invention.

[0073] Figure 3 This is a schematic diagram of the overall structure of the system for the directional co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust of the present invention, with a pretreatment unit.

[0074] Figure 4 This is a flowchart of the method for the directional co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust according to the present invention.

[0075] Figure 5The flowchart of the method for the directional co-production of high-purity manganese sulfate, manganese fluoride and potassium sulfate from blast furnace ferromanganese dust of the present invention includes a pretreatment process.

[0076] Reference numerals: 1: Reduction leaching unit; 101: Reduction leaching tank; 102: Leaching filter press; 103: Filter cake conveying device; 2: Extraction and defluorination unit; 201: Fluorine extraction tank; 202: Fluorine-manganese precipitation tank; 203: Fluorine extract liquid addition pipeline; 204: Manganese powder addition device; 205: Fluorine extract liquid circulation pipeline; 3: Impurity removal unit; 301: Oxidation and iron removal tank; 302: Gravity and hardness removal tank; 303: Saponification tank; 304: Impurity removal and filter press device; 305: Sulfide addition device; 306: Sludge discharge device; 4: Extraction and manganese removal unit; 401: Manganese extraction tank; 402: Back-extraction tank; 403: Crystallization device; 404: Manganese extract liquid addition pipeline; 405: Back-extraction liquid addition pipeline; 406: Manganese extract liquid circulation pipeline; 5: Ammonia recovery and circulation unit; 501: Alkali adjustment tank; 502: Ammonia stripping tower; 503: Liquid alkali addition pipeline; 6: Pure 601: Oxidative desulfurization tank; 602: pH adjustment tank; 603: Evaporation and salt separation device; 604: Sodium hypochlorite addition device; 605: Dilute sulfuric acid addition pipeline; 7: Pretreatment unit; 701: Three-stage countercurrent water washing device; 702: Two-stage flotation device; 703: Transition degradation tank; 704: Mixed salt sedimentation tank; 705: Oxidation-reduction tank; 706: Homogenization sedimentation tank; 707: Degradation agent addition mechanism; 708: Carbon dioxide inlet pipeline; 709: Oxidation and reduction agent addition mechanism; 710: Salt concentration detection device; 8: pH probe; S1: Dust removal ash conveying device; S2: Reduction leaching solution conveying pipeline; S3: Reduction exhaust pipeline; S4: Ammonia circulation conveying pipeline; S5: Fluoride salt discharge device; S6: Manganese salt discharge device; S7: Potassium salt discharge device; S8: Sodium salt discharge device; S9: Industrial water conveying pipeline. Detailed Implementation

[0077] The technical solution of the present invention will be illustrated below with examples. The scope of protection sought by the present invention includes, but is not limited to, the following embodiments.

[0078] A system for the directional co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust is disclosed. The system comprises a reduction leaching unit 1, an extraction defluorination unit 2, a purification unit 3, an extraction demanganese unit 4, an ammonia recovery and circulation unit 5, and a purification and salt separation unit 6, arranged in series. The ash inlet of the reduction leaching unit 1 is connected to a dust conveying device S1, and its liquid inlet is connected to a reduction leaching liquid conveying pipe S2. Its exhaust port is connected to the purification unit 3 via a reduction exhaust pipe S3. The exhaust port of the ammonia recovery and circulation unit 5 is connected to the purification unit 3 via an ammonia circulation conveying pipe S4. The salt outlet of the extraction defluorination unit 2 is connected to a fluoride salt discharge device S5. The salt outlet of the extraction demanganese unit 4 is connected to a manganese salt discharge device S6. The potassium salt outlet of the purification and salt separation unit 6 is connected to a potassium salt discharge device S7, and its sodium salt outlet is connected to a sodium salt discharge device S8.

[0079] Preferably, the reduction leaching unit 1 includes a reduction leaching tank 101 and a leaching filter press 102 arranged in series. The ash inlet of the reduction leaching tank 101 is connected to the dust removal ash conveying device S1, its liquid inlet is connected to the reduction leaching liquid conveying pipe S2, its exhaust port is connected to the reduction exhaust pipe S3, and its discharge port is connected to the feed inlet of the leaching filter press 102 through a conveying pipe. The liquid outlet of the filter press 102 is connected to the liquid inlet of the extraction defluorination unit 2 through a conveying pipe, and its filter cake outlet is connected to the filter cake conveying device 103.

[0080] Preferably, the extraction and defluorination unit 2 includes a fluorine extraction tank 201 and a fluorine-manganese precipitation tank 202 connected in series. The inlet of the fluorine extraction tank 201 is connected to the outlet of the filter press 102 via a delivery pipe, its extract outlet is connected to the inlet of the fluorine-manganese precipitation tank 202 via a delivery pipe, and its residual extract outlet is connected to the inlet of the impurity removal unit 3 via a delivery pipe. A fluorine extractant addition pipe 203 is connected to the inlet of the fluorine extraction tank 201. A manganese powder addition device 204 is connected to the inlet of the fluorine-manganese precipitation tank 202, its salt outlet is connected to the fluoride salt discharge device S5, and its clear liquid outlet is connected to the inlet of the fluorine extraction tank 201 via a fluorine extractant circulation pipe 205.

[0081] Preferably, the impurity removal unit 3 includes an iron oxidation removal tank 301, a gravity and hardening removal tank 302, a saponification tank 303, and an impurity removal pressure filter 304 connected in series. The inlet of the iron oxidation removal tank 301 is connected to the extraction residue outlet of the fluorine extraction tank 201 via a liquid delivery pipe, and its outlet is connected to the inlet of the gravity and hardening removal tank 302 via a liquid delivery pipe. The air inlet of the gravity and hardening removal tank 302 is connected to the reduction exhaust pipe S3, and a sulfide addition device 305 is connected to its dosing port. Its outlet is connected to the inlet of the saponification tank 303 via a liquid delivery pipe. The ammonia inlet of the saponification tank 303 is connected to the ammonia circulation conveying pipe S4, and its outlet is connected to the inlet of the impurity removal pressure filter 304 via a liquid delivery pipe. The drain port of the impurity removal and pressure filtration device 304 is connected to the inlet of the extraction and demanganese removal unit 4 through a liquid delivery pipeline, and its sewage outlet is connected to the sludge discharge device 306.

[0082] Preferably, the extraction and demanganese removal unit 4 includes a manganese extraction tank 401, a back-extraction tank 402, and a crystallization device 403 connected in series. The inlet of the manganese extraction tank 401 is connected to the outlet of the impurity removal and pressure filtration device 304 via a delivery pipe. A manganese extractant addition pipe 404 is connected to its inlet. The extractant outlet is connected to the inlet of the back-extraction tank 402 via a delivery pipe, and the residual extract outlet is connected to the inlet of the ammonia recovery and circulation unit 5 via a delivery pipe. The back-extraction tank 402 has a back-extraction liquid addition pipe 405 connected to its inlet. The back-extraction liquid outlet is connected to the inlet of the crystallization device 403 via a delivery pipe, and the residual extract outlet is connected to the inlet of the manganese extraction tank 401 via a manganese extractant circulation pipe 406. The salt outlet of the crystallization device 403 is connected to the manganese salt delivery device S6.

[0083] Preferably, the ammonia recovery and circulation unit 5 includes an alkali conditioning tank 501 and an ammonia stripping tower 502 connected in series. The inlet of the alkali conditioning tank 501 is connected to the extraction residue outlet of the manganese extraction tank 401, and its dosing port is connected to a liquid alkali addition pipe 503. Its outlet is connected to the inlet of the ammonia stripping tower 502 via a liquid delivery pipe. The ammonia outlet of the ammonia stripping tower 502 is connected to the ammonia circulation conveying pipe S4, and its outlet is connected to the inlet of the purification and salt separation unit 6.

[0084] Preferably, the purification and salt separation unit 6 includes an oxidative desulfurization tank 601, a pH adjustment tank 602, and an evaporative salt separation device 603 connected in series. The inlet of the oxidative desulfurization tank 601 is connected to the outlet of the ammonia stripping tower 502 via a delivery pipeline, and its outlet is connected to the inlet of the pH adjustment tank 602 via a delivery pipeline. A sodium hypochlorite addition device 604 is connected to its dosing port. The inlet of the pH adjustment tank 602 is also directly connected to the outlet of the ammonia stripping tower 502 via a delivery pipeline, and its outlet is connected to the inlet of the evaporative salt separation device 603 via a delivery pipeline. A dilute sulfuric acid addition pipeline 605 is connected to its acid addition port. The potassium salt outlet of the evaporative salt separation device 603 is connected to a potassium salt discharge device S7, and its sodium salt outlet is connected to a sodium salt discharge device S8.

[0085] Preferably, the system further includes a pretreatment unit 7, which comprises a three-stage countercurrent washing device 701, a two-stage flotation device 702, a transition degradation tank 703, a mixed salt sedimentation tank 704, a redox tank 705, and a homogenizing sedimentation tank 706. The ash inlet of the three-stage countercurrent washing device 701 is connected to the dust removal ash conveying device S1, its water inlet is connected to the industrial water conveying pipeline S9, its slag outlet is connected to the feed inlet of the two-stage flotation device 702 via a slag conveying mechanism, and its liquid outlet is connected to the liquid inlet of the mixed salt sedimentation tank 704 via a liquid conveying pipeline. The slag outlet of the two-stage flotation device 702 is connected to the feed inlet of the reductive leaching tank 101 via a slag conveying mechanism, and its liquid outlet is connected to the liquid inlet of the transition degradation tank 703 via a liquid conveying pipeline. A degradation agent addition mechanism 707 is connected to the dosing port of the transition degradation tank 703, and its discharge port is connected to the inlet of the oxidation-reduction tank 705 via a delivery pipeline. A carbon dioxide inlet pipeline 708 is connected to the air inlet of the mixed salt sedimentation tank 704, and its mixed salt outlet is connected to the inlet of the fluoride extraction tank 201 via a mixed salt conveying mechanism. Its discharge port is connected to the inlet of the oxidation-reduction tank 705 via a delivery pipeline. An oxidation and reduction agent addition mechanism 709 is connected to the dosing port of the oxidation-reduction tank 705, and its discharge port is connected to the inlet of the homogenizing sedimentation tank 706 via a delivery pipeline. The inlet of the homogenizing sedimentation tank 706 is also connected to the extraction residue discharge port of the manganese extraction tank 401 via a delivery pipeline, and its discharge port is connected to the inlet of the alkali adjustment tank 501 via a delivery pipeline.

[0086] Preferably, the transition degradation tank 703 is also equipped with a salt concentration detection device 710, and its discharge port is connected to the inlet of the two-stage flotation device 702 through a liquid delivery pipeline. The exhaust port of the pH adjustment tank 602 is connected to the carbon dioxide inlet pipeline 708 through a gas delivery pipeline.

[0087] Preferably, pH probes 8 are installed in the alkali adjustment tank 501, pH adjustment tank 602, and homogenization sedimentation tank 706.

[0088] Example 1

[0089] like Figure 1-3 As shown, a system for the directional co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust is disclosed. The system comprises a reduction leaching unit 1, an extraction defluorination unit 2, a purification unit 3, an extraction demanganese unit 4, an ammonia recovery and circulation unit 5, and a purification and salt separation unit 6, arranged in series. The ash inlet of the reduction leaching unit 1 is connected to a dust conveying device S1, and its liquid inlet is connected to a reduction leaching liquid conveying pipe S2. Its exhaust port is connected to the purification unit 3 via a reduction exhaust pipe S3. The exhaust port of the ammonia recovery and circulation unit 5 is connected to the purification unit 3 via an ammonia circulation conveying pipe S4. The salt outlet of the extraction defluorination unit 2 is connected to a fluoride salt discharge device S5. The salt outlet of the extraction demanganese unit 4 is connected to a manganese salt discharge device S6. The potassium salt outlet of the purification and salt separation unit 6 is connected to a potassium salt discharge device S7, and its sodium salt outlet is connected to a sodium salt discharge device S8.

[0090] Example 2

[0091] The embodiment 1 is repeated, except that the reduction leaching unit 1 includes a reduction leaching tank 101 and a leaching filter press 102 arranged in series. The ash inlet of the reduction leaching tank 101 is connected to the dust removal ash conveying device S1, its liquid inlet is connected to the reduction leaching liquid conveying pipe S2, its exhaust port is connected to the reduction exhaust pipe S3, and its discharge port is connected to the feed inlet of the leaching filter press 102 through a conveying pipe. The liquid outlet of the filter press 102 is connected to the liquid inlet of the extraction defluorination unit 2 through a conveying pipe, and its filter cake outlet is connected to the filter cake conveying device 103.

[0092] Example 3

[0093] The embodiment 2 is repeated, except that the extraction and defluorination unit 2 includes a fluorine extraction tank 201 and a fluorine-manganese precipitation tank 202 connected in series. The inlet of the fluorine extraction tank 201 is connected to the outlet of the filter press 102 via a liquid delivery pipe, its extract outlet is connected to the inlet of the fluorine-manganese precipitation tank 202 via a liquid delivery pipe, and its residual extract outlet is connected to the inlet of the impurity removal unit 3 via a liquid delivery pipe. A fluorine extractant addition pipe 203 is connected to the inlet of the fluorine extraction tank 201. A manganese powder addition device 204 is connected to the inlet of the fluorine-manganese precipitation tank 202, its salt outlet is connected to the fluoride salt discharge device S5, and its clear liquid outlet is connected to the inlet of the fluorine extraction tank 201 via a fluorine extractant circulation pipe 205.

[0094] Example 4

[0095] The embodiment 3 is repeated, except that the impurity removal unit 3 includes an iron oxidation removal tank 301, a gravity and hardening removal tank 302, a saponification tank 303, and an impurity removal pressure filter device 304 connected in series. The inlet of the iron oxidation removal tank 301 is connected to the extraction residue outlet of the fluorine extraction tank 201 via a liquid delivery pipe, and its outlet is connected to the inlet of the gravity and hardening removal tank 302 via a liquid delivery pipe. The air inlet of the gravity and hardening removal tank 302 is connected to the reduction exhaust pipe S3, and a sulfide addition device 305 is connected to its dosing port. Its outlet is connected to the inlet of the saponification tank 303 via a liquid delivery pipe. The ammonia inlet of the saponification tank 303 is connected to the ammonia circulation conveying pipe S4, and its outlet is connected to the inlet of the impurity removal pressure filter device 304 via a liquid delivery pipe. The drain port of the impurity removal and pressure filtration device 304 is connected to the inlet of the extraction and demanganese removal unit 4 through a liquid delivery pipeline, and its sewage outlet is connected to the sludge discharge device 306.

[0096] Example 5

[0097] The process repeats Example 4, except that the extraction and demanganese removal unit 4 includes a manganese extraction tank 401, a back-extraction tank 402, and a crystallization device 403 connected in series. The inlet of the manganese extraction tank 401 is connected to the outlet of the impurity removal and pressure filtration device 304 via a delivery pipe. A manganese extractant addition pipe 404 is connected to its inlet. The extractant outlet is connected to the inlet of the back-extraction tank 402 via a delivery pipe, and the residual extract outlet is connected to the inlet of the ammonia recovery and circulation unit 5 via a delivery pipe. A back-extraction liquid addition pipe 405 is connected to the inlet of the back-extraction tank 402. The back-extraction liquid outlet is connected to the inlet of the crystallization device 403 via a delivery pipe, and the residual extract outlet is connected to the inlet of the manganese extraction tank 401 via a manganese extractant circulation pipe 406. The salt outlet of the crystallization device 403 is connected to the manganese salt delivery device S6.

[0098] Example 6

[0099] The process repeats Example 5, except that the ammonia recovery and circulation unit 5 includes an alkali conditioning tank 501 and an ammonia stripping tower 502 connected in series. The inlet of the alkali conditioning tank 501 is connected to the extraction residue outlet of the manganese extraction tank 401, and its dosing port is connected to a liquid alkali addition pipe 503. Its outlet is connected to the inlet of the ammonia stripping tower 502 via a liquid delivery pipe. The ammonia outlet of the ammonia stripping tower 502 is connected to the ammonia circulation conveying pipe S4, and its outlet is connected to the inlet of the purification and salt separation unit 6.

[0100] Example 7

[0101] The process repeats Example 6, except that the purification and salt separation unit 6 includes an oxidative desulfurization tank 601, a pH adjustment tank 602, and an evaporative salt separation device 603 connected in series. The inlet of the oxidative desulfurization tank 601 is connected to the outlet of the ammonia stripping tower 502 via a delivery pipeline, and its outlet is connected to the inlet of the pH adjustment tank 602 via a delivery pipeline. A sodium hypochlorite addition device 604 is connected to its dosing port. The inlet of the pH adjustment tank 602 is also directly connected to the outlet of the ammonia stripping tower 502 via a delivery pipeline, and its outlet is connected to the inlet of the evaporative salt separation device 603 via a delivery pipeline. A dilute sulfuric acid addition pipeline 605 is connected to its acid addition port. The potassium salt outlet of the evaporative salt separation device 603 is connected to the potassium salt discharge device S7, and its sodium salt outlet is connected to the sodium salt discharge device S8.

[0102] Example 8

[0103] The system repeats Example 7, except that it also includes a pretreatment unit 7. The pretreatment unit 7 comprises a three-stage countercurrent washing device 701, a two-stage flotation device 702, a transition degradation tank 703, a mixed salt sedimentation tank 704, a redox tank 705, and a homogenizing sedimentation tank 706. The ash inlet of the three-stage countercurrent washing device 701 is connected to the dust removal ash conveying device S1, its water inlet is connected to the industrial water conveying pipeline S9, its slag outlet is connected to the feed inlet of the two-stage flotation device 702 via a slag conveying mechanism, and its liquid outlet is connected to the liquid inlet of the mixed salt sedimentation tank 704 via a liquid conveying pipeline. The slag outlet of the two-stage flotation device 702 is connected to the feed inlet of the reductive leaching tank 101 via a slag conveying mechanism, and its liquid outlet is connected to the liquid inlet of the transition degradation tank 703 via a liquid conveying pipeline. A degradation agent addition mechanism 707 is connected to the dosing port of the transition degradation tank 703, and its discharge port is connected to the inlet of the oxidation-reduction tank 705 via a delivery pipeline. A carbon dioxide inlet pipeline 708 is connected to the air inlet of the mixed salt sedimentation tank 704, and its mixed salt outlet is connected to the inlet of the fluoride extraction tank 201 via a mixed salt conveying mechanism. Its discharge port is connected to the inlet of the oxidation-reduction tank 705 via a delivery pipeline. An oxidation and reduction agent addition mechanism 709 is connected to the dosing port of the oxidation-reduction tank 705, and its discharge port is connected to the inlet of the homogenizing sedimentation tank 706 via a delivery pipeline. The inlet of the homogenizing sedimentation tank 706 is also connected to the extraction residue discharge port of the manganese extraction tank 401 via a delivery pipeline, and its discharge port is connected to the inlet of the alkali adjustment tank 501 via a delivery pipeline.

[0104] Example 9

[0105] Example 8 is repeated, except that a salt concentration detection device 710 is also installed in the transition degradation tank 703, and its discharge port is connected to the inlet of the two-stage flotation device 702 through a liquid delivery pipe. The exhaust port of the pH adjustment tank 602 is connected to the carbon dioxide inlet pipe 708 through a gas delivery pipe.

[0106] Example 10

[0107] Example 9 is repeated, except that pH probes 8 are installed in the alkali adjustment tank 501, pH adjustment tank 602, and homogenization sedimentation tank 706.

[0108] Example 11

[0109] A method for the directional co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust, the method comprising the following steps:

[0110] 1) Reduction leaching: Sulfuric acid and ferrous sulfate are used as leaching agents to leach blast furnace ferromanganese dust, and the leachate is obtained after solid-liquid separation. The gas generated during the leaching process is sent to step 3) to participate in the heavy and hard removal treatment.

[0111] 2) Defluorination: The leaching solution is extracted using a fluorine extractant to obtain a fluorine-containing extract and a defluorinated residue. Manganese powder is added to the fluorine-containing extract to prepare high-purity manganese fluoride. The defluorinated residue proceeds to the next step.

[0112] 3) Impurity removal: First, an oxidant is used to oxidize and remove iron from the defluorination residue, then sulfides are added for heavy and hard removal, and then ammonia is added for saponification. After solid-liquid separation, the defluorination residue is obtained.

[0113] 4) Manganese Extraction: The defluorination residue is extracted using a manganese extractant to obtain a manganese-containing extract and a manganese extraction residue. Dilute sulfuric acid is added to the manganese-containing extract for back-extraction, and the back-extraction solution is evaporated and crystallized to obtain high-purity manganese sulfate. The back-extraction residue is recycled as a manganese extractant, while the manganese extraction residue proceeds to the next process.

[0114] 5) Ammonia nitrogen removal: First, adjust the residual manganese extraction liquid to a strongly alkaline state and send it to the ammonia removal unit for ammonia removal treatment to obtain ammonia-removed wastewater. The removed ammonia nitrogen is recycled in the form of ammonia water to participate in the saponification treatment in step 3).

[0115] 6) Purification and salt separation: First, sodium hypochlorite solution is used to oxidize the ammonia removal wastewater, then acid is added to restore the wastewater to neutral, and finally, high-purity potassium sulfate and sodium chloride are obtained by temperature-variable evaporation and salt separation.

[0116] Example 12

[0117] 1) Ash washing: Industrial water is used to wash and leach the dust from blast furnace ferromanganese smelting to obtain washing slag and ash washing wastewater. Carbon dioxide is introduced into the ash washing wastewater to carry out a carbonation reaction. After solid-liquid separation, mixed salt and desalination wastewater are obtained. The mixed salt is combined with the flotation slag leachate from step 4) and then proceeded to step 5). The washing slag enters step 2), and the desalination wastewater enters step 3).

[0118] 2) Flotation: The washed residue obtained in step 1) is subjected to two-stage flotation to recover carbon powder and fluorite, respectively, yielding flotation residue and flotation water. Low-salt flotation water with a salt content below the set salt concentration is recycled for flotation of the washed residue. High-salt flotation water with a salt content above the set salt concentration undergoes COD degradation treatment before entering the wastewater pretreatment process. The flotation residue is then subjected to reduction leaching in step 4).

[0119] 3) Oxidation-reduction: The desalination wastewater obtained in step 1) is mixed with the high-salt flotation water after COD degradation obtained in step 2) to obtain mixed wastewater. Potassium permanganate solution is added to the mixed wastewater for oxidation treatment, followed by ferrous salt solution for reduction treatment. Finally, the reduced wastewater and manganese extraction residue are homogenized. The homogenized wastewater enters step 8) for ammonia nitrogen removal. Notably, the wastewater after ammonia nitrogen removal is not oxidized but directly mixed with acid to neutralize the wastewater. The carbon dioxide generated during homogenization and neutralization is recycled back to step 1) to participate in the carbonation reaction.

[0120] 4) Reduction leaching: Sulfuric acid and ferrous sulfate are used as leaching agents to leach the flotation residue, and the flotation residue leachate is obtained after solid-liquid separation.

[0121] 5) Defluorination: The flotation residue leaching solution is extracted using a fluorine extractant to obtain a fluorine-containing extract and a defluorinated residue. Manganese powder is added to the fluorine-containing extract to prepare high-purity manganese fluoride. The defluorinated residue proceeds to the next process.

[0122] 6) Impurity removal: First, an oxidant is used to oxidize and remove iron from the defluorination residue, then sulfides are added for heavy and hard removal, and then ammonia is added for saponification. After solid-liquid separation, the defluorination residue is obtained.

[0123] 7) Manganese Extraction: The defluorination residue is extracted using a manganese extractant to obtain a manganese-containing extract and a manganese extraction residue. Dilute sulfuric acid is added to the manganese-containing extract for back-extraction, and the back-extraction solution is evaporated and crystallized to obtain high-purity manganese sulfate. The back-extraction residue is recycled as a manganese extractant, while the manganese extraction residue is combined with the wastewater after reduction treatment in step 3) and homogenized.

[0124] 8) Ammonia nitrogen removal: The homogenized wastewater is first adjusted to a strongly alkaline state and then sent to an ammonia removal unit for ammonia removal treatment to obtain ammonia-removed wastewater. The removed ammonia nitrogen is recycled in the form of ammonia water to participate in the saponification treatment in step 6).

[0125] 9) Purification and salt separation: First, acid is used to restore the ammonia removal wastewater to neutral, and finally, high-purity potassium sulfate and sodium chloride are obtained by temperature-variable evaporation and salt separation.

[0126] Application Example 1

[0127] Using the system described in Example 7 and the method described in Example 11, high-purity manganese sulfate, manganese fluoride, and potassium sulfate are produced in a directional manner from blast furnace ferromanganese dust.

[0128] A mixed leachate (composed of 2 mol / L dilute sulfuric acid and solid ferrous sulfate in a volume-to-mass ratio of 2:1) was used to reduce and leach the dust from blast furnace ferromanganese smelting. The leachate was then obtained by pressure filtration. Meanwhile, the waste gas generated during the reduction and leaching process was recycled to participate in the subsequent sulfidation precipitation treatment.

[0129] Then, tertiary amine N235 was used as the fluorine extractant (3 times the volume of the leaching liquid) to extract the leaching liquid for 25 min, obtaining a fluorine-containing extract and a defluorinated residue. Manganese powder was added to the separated fluorine-containing extract to react, and after solid-liquid separation, manganese fluoride product (purity 98.47%) was obtained. Then, hydrogen peroxide (3.5% of the mass of the defluorinated residue) was added to the defluorinated residue for oxidation treatment for 15 min, sodium sulfide (0.5% of the mass of the defluorinated residue) was added for precipitation treatment for 12 min, and ammonia was added to adjust the pH of the defluorinated residue to 4 for saponification treatment for 15 min. After saponification, manganese extractant (composed of 40% di-(2-ethylhexyl)phosphonic acid P229 and 60% sulfonated kerosene by volume) was added to the defluorination residue at a ratio of 3:1 and extracted for 15 min to obtain manganese-containing extract and manganese-containing residue. Dilute sulfuric acid was added to the manganese-containing extract at a ratio of 1:3 for back-extraction for 15 min, and the manganese-containing back-extraction was evaporated, concentrated and crystallized to obtain manganese sulfate product (purity of 99.37%).

[0130] Sodium hydroxide solution was added to the manganese extraction residue to adjust the pH to 12. The strongly alkaline manganese extraction residue was then sent to an ammonia stripping tower for deammoniation treatment to obtain ammonia water (recycled for saponification) and ammonia-removed wastewater. The ammonia-removed wastewater was then oxidized for 15 minutes using sodium hypochlorite solution (1% by mass, added at 0.5% of the total mass of the ammonia-removed wastewater). Dilute sulfuric acid was then added to the ammonia-removed wastewater to adjust the pH of the desalination mother liquor to 6.5. The neutralized ammonia-removed wastewater was then evaporated and desalinated to obtain potassium sulfate (94.29% purity) and sodium chloride (92.34% purity). This embodiment of the process produces no wastewater or exhaust gas emissions.

[0131] Application Example 12

[0132] Using the system described in Example 10 and the method described in Example 12, high-purity manganese sulfate, manganese fluoride, and potassium sulfate are produced in a directional manner from blast furnace ferromanganese dust.

[0133] A three-stage countercurrent water washing and leaching process was used to extract dust from blast furnace ferromanganese smelting using industrial water at a water-to-ash ratio of 1:6.5. The resulting ash was then subjected to pressure filtration to obtain washed slag and washing wastewater (pH > 11). Carbon dioxide was introduced into the washing wastewater for carbonation, followed by solid-liquid separation to obtain mixed salt (which was then mixed with subsequent flotation slag leachate for defluorination) and desalination wastewater. Kerosene was used as a flotation agent (0.4% of the washed slag mass) to feed the washed slag into a primary flotation reactor for flotation to obtain carbon powder. Then, oleic acid was used as a collector (700 g / t), sodium carbonate as a pH adjuster (to adjust pH to 9), and water glass as a depressant (1900 g / t) to feed the decarbonized washed slag into a secondary flotation reactor for flotation to obtain fluorite. The salt concentration in the flotation wastewater was found to be approximately 107 g / L (the set value is 100 g / L). This portion of the flotation wastewater was then treated with hydrogen peroxide for oxidation and degradation before being mixed with the desalination wastewater for further oxidation treatment.

[0134] Dilute sulfuric acid and ferrous salt (composed of 2 mol / L dilute sulfuric acid and solid ferrous sulfate in a volume-to-mass ratio of 2:1) were used as leaching agents to reduce and leach the flotation residue after two stages of flotation for 40 min. After leaching, solid-liquid separation was performed to obtain calcium sulfate product and leachate. Then, tertiary amine N235 was used as a fluoride extractant (3 times the volume of the leachate) to extract the flotation residue leachate (containing mixed salts) for 25 min, obtaining fluoride-containing extract and defluorination residue. Manganese powder was added to the separated fluoride-containing extract for reaction, and manganese fluoride product (purity 97.53%) was obtained after solid-liquid separation. Finally, hydrogen peroxide (3.5% of the mass of the first extraction residue) was added to the defluorination residue for oxidation treatment for 15 min, sodium sulfide (0.45% of the mass of the defluorination residue) was added for precipitation treatment for 12 min, and ammonia was added to adjust the pH of the defluorination residue to 4 for saponification treatment for 10 min. After saponification, manganese extractant (composed of 40% di-(2-ethylhexyl)phosphonic acid P229 and 60% sulfonated kerosene by volume) was added to the primary extraction residue at a ratio of 3:1 and extracted for 15 min to obtain a manganese-containing extract and a manganese-containing residual liquid. Dilute sulfuric acid was added to the manganese-containing extract at a ratio of 1:3 for back-extraction for 15 min, and the manganese-containing back-extraction liquid was evaporated, concentrated, and crystallized to obtain manganese sulfate product (purity of 99.42%).

[0135] The flotation wastewater after oxidation and degradation treatment was mixed with desalination wastewater, and then 5% (by weight of the total mixed wastewater) of a 25% potassium permanganate solution was added, followed by stirring and oxidation treatment for 35 minutes. Then, 7% (by weight of the total ash washing wastewater) of a 20% ferrous sulfate solution was added to the oxidized wastewater, and the mixture was stirred and reduced for 35 minutes. After the treatment was completed, solid-liquid separation was performed to obtain pretreated wastewater.

[0136] The pretreated wastewater and manganese extraction residue were mixed and homogenized. After solid-liquid separation, sodium hydroxide solution was added to the filtrate wastewater to adjust the pH to 12. The strongly alkaline wastewater was then sent to an ammonia stripping tower for ammonia removal treatment to obtain ammonia water (recycled for chemical treatment) and ammonia-removed wastewater. Dilute sulfuric acid was added to the ammonia-removed wastewater to adjust its pH back to 6.5. The neutralized ammonia-removed wastewater was then subjected to evaporation and salt separation treatment to obtain potassium sulfate (95.05% purity) and sodium chloride (94.44% purity). The carbon dioxide generated during homogenization and pH adjustment was recycled for carbonation treatment. This embodiment of the process has no wastewater or exhaust gas emissions.

Claims

1. A system for the directional co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust, characterized in that: The system includes a reduction leaching unit (1), an extraction defluorination unit (2), a purification unit (3), an extraction demanganese unit (4), an ammonia recovery and circulation unit (5), and a purification and salt separation unit (6) arranged in series. The ash inlet of the reduction leaching unit (1) is connected to a dust removal ash conveying device (S1), the liquid inlet is connected to a reduction leaching liquid conveying pipe (S2), and the exhaust port is connected to the purification unit (3) through a reduction exhaust pipe (S3). The exhaust port of the ammonia recovery and circulation unit (5) is connected to the purification unit (3) through an ammonia circulation conveying pipe (S4). The salt outlet of the extraction defluorination unit (2) is connected to a fluoride salt discharge device (S5). The salt outlet of the extraction demanganese unit (4) is connected to a manganese salt discharge device (S6). The potassium salt outlet of the purification and salt separation unit (6) is connected to a potassium salt discharge device (S7), and its sodium salt outlet is connected to a sodium salt discharge device (S8).

2. The system according to claim 1, characterized in that: The reduction leaching unit (1) includes a reduction leaching tank (101) and a leaching filter press (102) arranged in series. The ash inlet of the reduction leaching tank (101) is connected to the dust removal ash conveying device (S1), its liquid inlet is connected to the reduction leaching liquid conveying pipeline (S2), its exhaust port is connected to the reduction exhaust pipeline (S3), and its discharge port is connected to the feed inlet of the leaching filter press (102) through a conveying pipeline. The liquid outlet of the filter press (102) is connected to the liquid inlet of the extraction defluorination unit (2) through a conveying pipeline, and its filter residue outlet is connected to the filter cake conveying device (103). The extraction and defluorination unit (2) includes a fluorine extraction tank (201) and a fluorine-manganese precipitation tank (202) connected in series. The inlet of the fluorine extraction tank (201) is connected to the outlet of the filter press (102) through a liquid delivery pipe. Its extract outlet is connected to the inlet of the fluorine-manganese precipitation tank (202) through a liquid delivery pipe. Its residual extract outlet is connected to the inlet of the impurity removal unit (3) through a liquid delivery pipe. A fluorine extract addition pipe (203) is connected to the liquid inlet of the fluorine extraction tank (201). A manganese powder addition device (204) is connected to the feed inlet of the fluorine-manganese precipitation tank (202). Its salt outlet is connected to the fluorine salt discharge device (S5). Its clear liquid outlet is connected to the liquid inlet of the fluorine extraction tank (201) through a fluorine extract circulation pipe (205).

3. The system according to claim 2, characterized in that: The impurity removal unit (3) includes an iron oxidation removal tank (301), a gravimetric and hardening removal tank (302), a saponification tank (303), and an impurity removal filter press (304) connected in series. The inlet of the iron oxidation removal tank (301) is connected to the extraction residue outlet of the fluorine extraction tank (201) via a liquid delivery pipe, and its outlet is connected to the inlet of the gravimetric and hardening removal tank (302) via a liquid delivery pipe. The air inlet of the gravimetric and hardening removal tank (302) is connected to the reduction exhaust pipe (S3), and its chemical dosing port is connected to the gravimetric and hardening removal tank (302). The upper part is connected to a sulfide addition device (305), whose outlet is connected to the inlet of the saponification tank (303) through a liquid conveying pipe; the ammonia inlet of the saponification tank (303) is connected to the ammonia circulation conveying pipe (S4), and its outlet is connected to the inlet of the impurity removal filter press (304) through a liquid conveying pipe; the outlet of the impurity removal filter press (304) is connected to the inlet of the extraction and demanganese removal unit (4) through a liquid conveying pipe, and its sludge discharge outlet is connected to the sludge discharge device (306); and / or The extraction and demanganese unit (4) includes a manganese extraction tank (401), a back-extraction tank (402), and a crystallization device (403) connected in series. The inlet of the manganese extraction tank (401) is connected to the outlet of the impurity removal and pressure filtration device (304) through a liquid delivery pipe. A manganese extract liquid addition pipe (404) is connected to its inlet. The outlet of the extract liquid is connected to the inlet of the back-extraction tank (402) through a liquid delivery pipe. The outlet of the residual extract liquid is connected to the inlet of the back-extraction tank (402) through a liquid delivery pipe. The pipeline is connected to the inlet of the ammonia recovery circulation unit (5); the inlet of the back-extraction tank (402) is connected to the back-extraction liquid addition pipeline (405), the back-extraction liquid outlet is connected to the inlet of the crystallization device (403) through the liquid delivery pipeline, and the back-extraction residual liquid outlet is connected to the inlet of the manganese extraction tank (401) through the manganese extraction liquid circulation pipeline (406); the salt outlet of the crystallization device (403) is connected to the manganese salt discharge device (S6).

4. The system according to claim 3, characterized in that: The ammonia recovery and circulation unit (5) includes an alkali conditioning tank (501) and an ammonia stripping tower (502) connected in series. The inlet of the alkali conditioning tank (501) is connected to the outlet of the extraction residue of the manganese extraction tank (401), and a liquid alkali addition pipe (503) is connected to its dosing port. Its outlet is connected to the inlet of the ammonia stripping tower (502) through a liquid delivery pipe. The ammonia outlet of the ammonia stripping tower (502) is connected to the ammonia circulation and delivery pipe (S4), and its outlet is connected to the inlet of the purification and salt separation unit (6). The purification and salt separation unit (6) includes an oxidative desulfurization tank (601), a pH adjustment tank (602), and an evaporative salt separation device (603) connected in series. The inlet of the oxidative desulfurization tank (601) is connected to the outlet of the ammonia stripping tower (502) through a liquid delivery pipeline. Its outlet is connected to the inlet of the pH adjustment tank (602) through a liquid delivery pipeline. A sodium hypochlorite addition device (604) is connected to its dosing port. The inlet of the pH adjustment tank (602) is also directly connected to the outlet of the ammonia stripping tower (502) through a liquid delivery pipeline. Its outlet is connected to the inlet of the evaporative salt separation device (603) through a liquid delivery pipeline. A dilute sulfuric acid addition pipeline (605) is connected to its acid addition port. The potassium salt outlet of the evaporative salt separation device (603) is connected to the potassium salt discharge device (S7), and its sodium salt outlet is connected to the sodium salt discharge device (S8).

5. The system according to claim 4, characterized in that: The system also includes a pretreatment unit (7), which includes a three-stage countercurrent water washing device (701), a two-stage flotation device (702), a transition degradation tank (703), a mixed salt sedimentation tank (704), a redox tank (705), and a homogenizing sedimentation tank (706). The ash inlet of the three-stage countercurrent water washing device (701) is connected to a dust removal ash conveying device (S1), its water inlet is connected to an industrial water conveying pipeline (S9), its slag outlet is connected to the feed inlet of the two-stage flotation device (702) via a slag conveying mechanism, and its liquid outlet is connected to the liquid inlet of the mixed salt sedimentation tank (704) via a liquid conveying pipeline. The slag outlet of the two-stage flotation device (702) is connected to the feed inlet of the reduction leaching tank (101) via a slag conveying mechanism, and its liquid outlet is connected to the liquid inlet of the transition degradation tank (703) via a liquid conveying pipeline. The degradation tank (703) is connected to a degradation agent addition mechanism (707) at the dosing port, and its discharge port is connected to the inlet of the oxidation-reduction tank (705) through a liquid conveying pipe; the mixed salt sedimentation tank (704) is connected to a carbon dioxide inlet pipe (708) at the air inlet, and its mixed salt outlet is connected to the feed inlet of the fluorine extraction tank (201) through a mixed salt conveying mechanism, and its discharge port is connected to the inlet of the oxidation-reduction tank (705) through a liquid conveying pipe; the oxidation-reduction tank (705) is connected to an oxidation and reduction agent addition mechanism (709) at the dosing port, and its discharge port is connected to the inlet of the homogenizing sedimentation tank (706) through a liquid conveying pipe; the inlet of the homogenizing sedimentation tank (706) is also connected to the extraction residue discharge port of the manganese extraction tank (401) through a liquid conveying pipe, and its discharge port is connected to the inlet of the alkali adjustment tank (501) through a liquid conveying pipe.

6. The system according to claim 5, characterized in that: The transition degradation tank (703) is also equipped with a salt concentration detection device (710), and its discharge port is connected to the inlet of the two-stage flotation unit (702) via a liquid delivery pipeline; the exhaust port of the pH adjustment tank (602) is connected to the carbon dioxide inlet pipeline (708) via a gas delivery pipeline; and / or pH probes (8) are installed in the alkali adjustment tank (501), pH adjustment tank (602), and homogenization sedimentation tank (706).

7. A method for the directional co-production of high-purity manganese sulfate, manganese fluoride, and potassium sulfate from blast furnace ferromanganese dust, characterized in that: The method includes the following steps: 1) Reduction leaching: Sulfuric acid and ferrous sulfate are used as leaching agents to leach blast furnace ferromanganese dust, and the leachate is obtained after solid-liquid separation; wherein, the gas generated during the leaching process is sent to step 3) to participate in the heavy removal and hardening treatment. 2) Defluorination: The leaching solution is extracted with a fluorine extractant to obtain a fluorine-containing extract and a defluorinated residue; manganese powder is added to the fluorine-containing extract to prepare high-purity manganese fluoride; the defluorinated residue is then proceeded to the next step. 3) Impurity removal: First, an oxidant is used to oxidize and remove iron from the defluorination residue, then sulfides are added for heavy and hard removal, then ammonia is added for saponification, and the defluorination residue is obtained after solid-liquid separation. 4) Manganese extraction: The defluorination residue is extracted with a manganese extractant to obtain a manganese-containing extract and a manganese extraction residue; dilute sulfuric acid is added to the manganese-containing extract for back-extraction, and the back-extraction solution is evaporated and crystallized to obtain high-purity manganese sulfate; the back-extraction residue is recycled as a manganese extractant, while the manganese extraction residue enters the next process. 5) Removal of ammonia nitrogen: First, adjust the residual manganese extraction liquid to strong alkalinity and send it to the ammonia removal device for ammonia removal treatment to obtain ammonia-removed wastewater; the removed ammonia nitrogen is recycled in the form of ammonia water to participate in the saponification treatment in step 3). 6) Purification and salt separation: First, sodium hypochlorite solution is used to oxidize the ammonia removal wastewater, then acid is added to restore the wastewater to neutral, and finally, high-purity potassium sulfate and sodium chloride are obtained by temperature-variable evaporation and salt separation.

8. The method according to claim 7, characterized in that: In step 1), the mass concentration of the sulfuric acid is 0.5-3 mol / L; the mass of the ferrous sulfate solid is 30-60% of the mass of the blast furnace ferromanganese dust; and / or In step 1), the volume-to-mass ratio of sulfuric acid to ferrous sulfate in the leaching agent is 1.5-4:

1.

9. The method according to claim 8, characterized in that: In step 1), the mass concentration of the sulfuric acid is 1-1.5 mol / L; the mass of the ferrous sulfate solid is 40-50% of the mass of the blast furnace ferromanganese dust; and / or In step 1), the volume-to-mass ratio of sulfuric acid to ferrous sulfate in the leaching agent is 2-3.5:

1.

10. The method according to claim 8, characterized in that: The volume-to-mass ratio of the leaching agent to the blast furnace ferromanganese dust is 0.8-2.5:

1.

11. The method according to claim 10, characterized in that: The volume-to-mass ratio of the leaching agent to the blast furnace ferromanganese dust is 1-2:

1.

12. The method according to claim 7, characterized in that: In step 2), the fluorine extractant is tertiary amine N235, and its dosage is 2-6 times the total volume of the leaching solution; the extraction time is 5-25 min; and / or In step 3), the iron removal by oxidation is carried out using hydrogen peroxide or ozone, with an addition amount of 0.3-6% of the mass of the defluorination residue; the removal of heavy metals and hardness is carried out by sulfide precipitation treatment using one or more of barium sulfide, sodium sulfide, and hydrogen sulfide, with an addition amount of 0.2-0.7% of the mass of the defluorination residue; the saponification treatment is carried out by adjusting the pH of the defluorination residue to 3.5-5.5 using ammonia.

13. The method according to claim 12, characterized in that: In step 2), the amount of fluorine extractant used is 3-5 times the total volume of the leaching solution; the extraction time is 10-20 min; and / or In step 3), the amount of iron removal by oxidation is 0.5-4% of the mass of the defluorination residue; the amount of heavy metal removal and hardening removal is 0.4-0.7% of the mass of the defluorination residue; and the saponification treatment involves adjusting the pH of the defluorination residue to 4-5 using ammonia.

14. The method according to claim 7, characterized in that: In step 4), the manganese extractant is a mixed extractant composed of 30-50% di-(2-ethylhexyl)phosphonic acid P229 and 50-70% sulfonated kerosene; the extraction ratio is 1-4:1; the extraction time is 5-20 min; and / or In step 4), the back-extraction is a multi-stage countercurrent back-extraction; the concentration of the dilute sulfuric acid is 10-30%; the extraction ratio of each stage is 1:2-4; and the back-extraction time of each stage is 8-20 min.

15. The method according to claim 14, characterized in that: In step 4), the extraction ratio is 2-3:1; the extraction time is 8-15 min; and / or In step 4), the back-extraction is a 2-3 stage countercurrent back-extraction; the concentration of the dilute sulfuric acid is 15-25%; the extraction ratio of each stage is 1:2-3; and the back-extraction time of each stage is 10-15 min.

16. The method according to claim 7, characterized in that: In step 5), adjusting the residual manganese extraction liquor to a strongly alkaline state involves adjusting the pH of the residual manganese extraction liquor to 10-14 using liquid alkali; the ammonia removal device is a stripping tower or an ammonia stripping tower; and / or In step 6), the mass concentration of the sodium hypochlorite solution is 0.5-3%; the amount added is 0.01-2% of the wastewater mass; the addition of acid to neutralize the wastewater specifically involves adding dilute sulfuric acid to neutralize the pH of the wastewater to 6-7.

5.

17. The method according to claim 16, characterized in that: In step 5), adjusting the residual manganese extraction solution to a strongly alkaline state involves adjusting the pH of the residual manganese extraction solution to 11-12 using liquid alkali; and / or In step 6), the mass concentration of the sodium hypochlorite solution is 0.8-2%; the amount added is 0.05-1.5% of the wastewater mass; the addition of acid to neutralize the wastewater specifically involves adding dilute sulfuric acid to neutralize the pH of the wastewater to 6.5-7.

18. The method according to any one of claims 7-17, characterized in that: The method also includes the following preprocessing steps: i) Washing ash: Industrial water is used to wash and leach the dust from the blast furnace ferromanganese removal process to obtain washing slag and washing ash wastewater. Carbon dioxide is introduced into the washing ash wastewater to carry out a carbonation reaction. After solid-liquid separation, mixed salt and desalination wastewater are obtained. The mixed salt is combined with the leachate from step 1) and then proceeded to step 2). The washing slag enters step ii), and the desalination wastewater enters step iii). ii) Flotation: The water washing residue obtained in step i) is subjected to two-stage flotation to recover carbon powder and fluorite respectively, and flotation residue and flotation water are obtained; the low-salt flotation water with a salt content lower than the salt concentration set value is recycled to participate in the flotation of the water washing residue, and the high-salt flotation water with a salt content higher than the salt concentration set value is subjected to COD degradation treatment and then enters the wastewater pretreatment; the flotation residue enters step 1) for reduction leaching; iii) Oxidation-reduction: The desalination wastewater obtained in step i) is mixed with the high-salt flotation water after COD degradation obtained in step ii) to obtain mixed wastewater. Potassium permanganate solution is added to the mixed wastewater for oxidation treatment, followed by ferrous salt solution for reduction treatment. Finally, the wastewater after reduction treatment is homogenized with the manganese extraction residue. The homogenized wastewater enters step 5) for ammonia nitrogen removal. The wastewater after ammonia nitrogen removal is not oxidized but is directly added to the acid backwash wastewater to neutrality. The carbon dioxide generated during homogenization and backwashing is recycled to step i) to participate in the carbonation reaction.

19. The method according to claim 18, characterized in that: In step i), the water washing and leaching is a three-stage countercurrent water washing; the water-to-cement ratio during water washing is 1-8:1; and / or In step ii), the flotation agent used for recovering carbon powder is kerosene, and its dosage is 0.1-0.8% of the raw material mass; and / or In step ii), the collector used for flotation recovery of fluorite is one of oleic acid, oxidized paraffin soap, CM-10, and No. 2 oil, with a dosage of 550-1100 g / t; the pH adjuster is sodium carbonate, with the pH value adjusted to 8-10; and the inhibitor is water glass, with a dosage of 1600-2500 g / t.

20. The method according to claim 19, characterized in that: In step i), the water-to-cement ratio during washing is 1-8:1; and / or In step ii), the amount of flotation reagent added during the flotation recovery of carbon powder is 0.2-0.5% of the raw material mass; and / or In step ii), the amount of collector added during flotation recovery of fluorite is 600-900 g / t; the pH value is adjusted to 9-10; and the amount of inhibitor added is 1800-2200 g / t.

21. The method according to claim 18, characterized in that: The salt concentration is set at 80-120 g / L; and / or The COD degradation treatment specifically involves oxidative degradation using hydrogen peroxide or Fenton's reagent.

22. The method according to claim 21, characterized in that: The salt concentration is set at 90-110 g / L.

23. The method according to claim 19, characterized in that: In step iii), the concentration of the potassium permanganate solution is 15-40%; its addition amount is 2-10% of the total mass of the wastewater; the oxidation treatment time is 5-50 min; and / or In step iii), the concentration of the ferrous salt solution is 10-30%; the amount added is 3-10% of the total mass of the wastewater; and the reduction treatment time is 5-50 min.

24. The method according to claim 23, characterized in that: In step iii), the concentration of the potassium permanganate solution is 20-30%; its addition amount is 3-8% of the total mass of the wastewater; the oxidation treatment time is 10-30 min; and / or In step iii), the concentration of the ferrous salt solution is 15-25%; the amount added is 4-8% of the total mass of the wastewater; and the reduction treatment time is 10-30 min.

25. The method according to claim 23, characterized in that: The ferrous salt is ferrous sulfate and / or ferrous chloride; and / or The pH of the homogenized wastewater is 6-8.

5.

26. The method according to claim 25, characterized in that: The pH of the homogenized wastewater is 7-8.

27. The method according to any one of claims 7-17 and 19-26, characterized in that: The dust collected during the blast furnace ferromanganese smelting process is dust containing iron, manganese, fluorine, alkali metals, carbonate, and sulfite.

Images