Method and system for recycling dust of blast furnace ferromanganese smelting

Abstract

The application discloses a method and system for recycling dust removal ash of blast furnace manganese iron smelting, and first proposes a technical route for recycling carbon powder, fluorite, manganese fluoride, manganese sulfate, potassium bicarbonate, potassium sulfate, sodium chloride and other valuable resources by water washing of the dust removal ash of blast furnace manganese iron smelting. The water washing slag and washing wastewater of the dust removal ash of blast furnace manganese iron smelting are simultaneously treated in a cooperative manner, the process can be designed according to the characteristics of the washing wastewater and the water washing slag, the multistage recovery of the valuable resources is realized, new impurities are not introduced, and the added value of the recovered resources is improved. In addition, the whole process does not discharge wastewater and waste gas, has high economic value and 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 method and system for the resource utilization of dust from blast furnace ferromanganese smelting, belonging to the technical field of solid waste ash resource utilization treatment 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 from electric furnaces, whose composition differs from that of dust from blast furnace ferromanganese smelting. Research shows 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. Furthermore, existing technologies directly transport the washed residue for disposal without proper resource recovery, resulting in a waste of valuable resources. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes for the first time a technical approach that utilizes blast furnace ferromanganese smelting dust ash washing to recover various valuable resources such as carbon powder, fluorite, manganese fluoride, manganese sulfate, potassium bicarbonate, potassium sulfate, and sodium chloride. This invention addresses the unique characteristics of ash washing wastewater and slag washing by employing a pre-oxidation coupled with reduction purification process to efficiently remove sulfite and high-valent iron and manganese from the wastewater without introducing new impurities. It also utilizes two-stage flotation to recover carbon powder and fluorite, and further achieves resource recovery of fluorine and manganese through reduction leaching and multi-stage extraction. Specifically designed to remove sulfite and high-valent manganese and iron from the wastewater without introducing impurities, this process significantly improves the purity of the recovered potassium salts. Furthermore, by coupling low-cost pre-treated wastewater with leaching residue for co-purification and ammonia recycling, pollutants are synergistically removed, reducing wastewater treatment costs and enabling ammonia nitrogen recycling within the system. Finally, addressing the challenges and complexities of separating carbonate, sulfate, and chloride ions, and considering the carbon dioxide consumption required for potassium bicarbonate preparation, this invention employs acid hydrolysis of carbonates to recover carbon dioxide, recycle carbon, and regulate the liquid-phase anion composition. This co-produces high-purity potassium bicarbonate and potassium sulfate, reducing bicarbonate recovery costs and simplifying salt separation. The entire process is wastewater and gas-free, offering high economic value and meeting green environmental protection 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 method for resource utilization of dust from blast furnace ferromanganese smelting is provided.

[0008] A method for resource utilization of dust from blast furnace ferromanganese smelting, the method comprising the following steps:

[0009] 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.

[0010] 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. The flotation water is divided into high-salt flotation water and low-salt flotation water based on whether the salt concentration exceeds a set value. The low-salt flotation water is recycled for flotation of the washed residue, while the high-salt flotation water undergoes COD degradation treatment before entering the wastewater pretreatment process.

[0011] 3) Wastewater pretreatment: The ash washing wastewater obtained in step 1) is mixed with the high-salt flotation water obtained after COD degradation in step 2) to obtain mixed wastewater. An oxidant is first added to the mixed wastewater for oxidation treatment. Then, a reducing agent is added to the oxidized wastewater for reduction treatment. After solid-liquid separation, pretreated wastewater is obtained.

[0012] 4) Reduction leaching: Dilute sulfuric acid and ferrous salt are used as leaching agents to leach the flotation residue obtained in step 2). After leaching, solid-liquid separation is performed to obtain calcium sulfate product and leaching solution.

[0013] 5) Multi-stage extraction: First, the leachate obtained in step 4) is extracted using a fluorine extractant to obtain a fluorine extract and a primary extraction residue. Manganese powder is added to the fluorine extract to prepare manganese fluoride. Then, the primary extraction residue is sequentially treated with oxidation to remove iron, sulfidation to remove heavy metals, and saponification before being extracted with a manganese extractant to obtain a manganese extract and a secondary extraction residue. Dilute sulfuric acid is added to the manganese extract for back-extraction and evaporation crystallization to obtain manganese sulfate. Finally, the secondary extraction residue is homogenized with the pretreated wastewater obtained in step 3), and after solid-liquid separation, sludge and a mixed clear liquid are obtained. The sludge is transported for disposal, and the mixed clear liquid enters the alkali adjustment and ammonia removal step.

[0014] 6) Alkalinity Adjustment and Ammonia Removal: First, adjust the mixed clear liquid obtained in step 5) to a weakly alkaline state using alkali to precipitate and remove zinc. Then, adjust the zinc-removed wastewater to a strongly alkaline state using alkali and send it to the ammonia removal unit for ammonia removal treatment, obtaining ammonia-removed wastewater for the next process.

[0015] 7) Concentration to produce potassium bicarbonate: The ammonia-removing wastewater obtained in step 6) is concentrated, and then carbon dioxide is introduced into the concentrated wastewater to carry out a carbonation reaction. After solid-liquid separation, high-purity potassium bicarbonate and desalination mother liquor are obtained.

[0016] 8) Circulating evaporation and salt separation: Based on whether the sulfate ion concentration in the desalination mother liquor exceeds the set sulfate concentration value, the desalination mother liquor is divided into high-sulfur mother liquor and low-sulfur mother liquor. The low-sulfur mother liquor is returned and combined with the ammonia removal wastewater for step 7). The high-sulfur mother liquor is adjusted to neutral by adding acid, and then high-purity potassium sulfate and sodium chloride are recovered through temperature-controlled evaporation and salt separation.

[0017] Preferably, the method further includes the following steps:

[0018] 9) The carbon dioxide generated during the process of adding acid to adjust the high-sulfur mother liquor to neutrality in step 8) is recycled to step 7) for carbonation reaction. The ammonia gas removed in step 6) is recovered as ammonia water and recycled to step 5) for saponification treatment and / or the potassium bicarbonate obtained in step 7) is used in step 5) for saponification treatment.

[0019] 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.

[0020] Preferably, in step 1), the water washing is a three-stage countercurrent water washing. The water-to-ash ratio during water washing is 1-7:1, preferably 2-5:1.

[0021] Preferably, in step 1), the ash washing wastewater is strongly alkaline wastewater, preferably wastewater with a pH > 11.

[0022] Preferably, in step 2), the flotation agent used for recovering carbon powder is kerosene, and the amount added is 0.1-0.8% of the raw material mass, preferably 0.2-0.5%.

[0023] Preferably, in step 2), 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 500-1000 g / t, preferably 600-800 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 1800-2500 g / t, preferably 2000-2400 g / t.

[0024] Preferably, in step 2), the salt concentration is set to 80-120 g / L, more preferably 90-110 g / L.

[0025] Preferably, in step 2), the COD degradation treatment specifically involves oxidation treatment using hydrogen peroxide or Fenton's reagent.

[0026] Preferably, in step 3), the oxidant is a potassium permanganate solution. The concentration (mass concentration) of the potassium permanganate solution is 15-40%, preferably 20-30%.

[0027] Preferably, in step 3), the amount of oxidant added is 2-8% of the total mass of the wastewater, more preferably 3-5%. The oxidation treatment time is 5-50 min, more preferably 10-30 min.

[0028] Preferably, in step 3), the reducing agent is a soluble ferrous salt solution. The concentration (mass concentration) of the soluble ferrous salt solution is 10-30%, preferably 15-25%. Preferably, the soluble ferrous salt is ferrous sulfate and / or ferrous chloride, preferably ferrous sulfate. The amount of reducing agent added is 3-9% of the total mass of the wastewater, preferably 4-6%. The reduction treatment time is 5-50 min, preferably 10-30 min.

[0029] Preferably, in step 4), the ferrous salt is one of elemental iron powder, ferrous chloride, and ferrous sulfate, with ferrous sulfate being the most preferred.

[0030] Preferably, in step 4), the pH of the leaching solution is 1-4, more preferably 2-3. The volume-to-mass ratio of sulfuric acid to ferrous sulfate in the leaching solution is 1.5-4:1, more preferably 2-3.5:1.

[0031] Preferably, in step 5), the fluorine extractant is tertiary amine N235 (trioctyldecyl tertiary amine), and its amount is 2-5 times the total volume of the extract, preferably 2-4 times. The extraction time is 5-30 min, preferably 10-20 min.

[0032] Preferably, in step 5), the iron removal by oxidation is performed using hydrogen peroxide or ozone (preferably hydrogen peroxide), with an addition amount of 0.5-5% of the mass of the primary extraction residue, preferably 0.8-4%. The weight removal by sulfidation is performed using one or more of barium sulfide, sodium sulfide, and hydrogen sulfide (preferably barium sulfide) for sulfidation precipitation, with an addition amount of 0.2-0.8% of the mass of the primary extraction residue, preferably 0.3-0.5%. The saponification treatment involves adjusting the pH of the primary extraction residue to 3.5-5.5 using ammonia and / or potassium bicarbonate, preferably to 4-5.

[0033] Preferably, in step 5), 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. The saponification rate of the extractant is 30-65%, preferably 35-60%.

[0034] Preferably, in step 5), the back-extraction is a multi-stage countercurrent back-extraction, preferably 2-3 stages. The concentration (mass 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 is 8-20 min, preferably 10-15 min.

[0035] Preferably, in step 6), the alkali is sodium hydroxide and / or potassium hydroxide. Adjusting to weak alkalinity means adjusting the pH of the wastewater to 7.5-8.5, preferably 7.8-8.3. Adjusting to strong alkalinity means adjusting the pH of the wastewater to greater than 10, preferably 11-12.

[0036] Preferably, in step 6), the ammonia removal device is a stripping tower or an ammonia stripping device, preferably an ammonia stripping device.

[0037] Preferably, in step 7), the concentration factor of the ammonia-removing wastewater is 2-7 times, and more preferably 3-5 times.

[0038] Preferably, in step 8), the sulfate concentration is set to 130-180 g / L, more preferably 140-160 g / L.

[0039] Preferably, in step 8), the addition of acid to adjust to neutral specifically involves adding dilute sulfuric acid to adjust the pH of the wastewater to 6-7, preferably 6.5-7.

[0040] According to a second embodiment of the present invention, a system for the resource utilization of dust from blast furnace ferromanganese smelting is provided.

[0041] A system for the resource utilization of dust from blast furnace ferromanganese smelting, or a system for the method described in the first embodiment, is disclosed. The system includes a three-stage countercurrent water washing device, a wastewater treatment unit for ash washing, and a slag treatment unit for water washing. The wastewater treatment unit includes, in series, an oxidation-reduction tank, a homogenization tank, an ammonia stripping device, an evaporation and concentration device, a carbonation reaction tank, a first transition tank, a setback tank, and an evaporation and salt separation device. The slag treatment unit includes, in series, a two-stage flotation device, a reduction leaching tank, an extraction and defluorination tank, a purification tank, a saponification and manganese extraction tank, and a reverse extraction and crystallization tank for manganese extraction.

[0042] Preferably, the ash inlet of the three-stage countercurrent washing device is connected to a manganese iron ash conveying mechanism, and its water inlet is connected to an industrial water conveying pipeline. The drain outlet of the three-stage countercurrent washing device is connected to the water inlet of the oxidation-reduction tank through a water conveying pipeline, and its slag discharge outlet is connected to two-stage flotation devices through a slag conveying mechanism.

[0043] Preferably, the inlet of the carbonation reaction tank is connected to a carbon dioxide delivery pipeline. A sulfate ion sampling and detection meter is installed in the first transition tank, and its outlet is connected to the inlet of the evaporation and concentration device via a first circulating water pipeline. The residual liquid outlet of the saponification manganese extraction tank is connected to the inlet of the homogenization tank via a water pipeline.

[0044] Preferably, the system also includes a second transition tank and a COD degradation tank. The outlets of the two flotation stages are connected to the inlet of the second transition tank via water supply pipes. The outlet of the second transition tank is connected to the inlet of the COD degradation tank via a water supply pipe, and the outlet of the COD degradation tank is connected to the inlet of the oxidation-reduction tank via a water supply pipe. A salt concentration meter is installed in the second transition tank, and the outlet of the second transition tank is also connected to the inlet of the two flotation stages via a second circulating water supply pipe.

[0045] Preferably, the redox tank is equipped with a potassium permanganate addition mechanism and a ferrous salt addition mechanism. The ammonia stripping device is connected to a liquid alkali addition pipe, and a first pH probe is installed inside the pipe. The settling tank is equipped with a first acid addition mechanism, and a second pH probe is installed inside the settling tank.

[0046] Preferably, the reduction leaching tank is equipped with a mixed leaching agent addition mechanism. The extraction and defluorination tank is equipped with a fluorine extractant addition pipe. The impurity removal tank is equipped with an oxidant addition mechanism and a reducing agent addition mechanism. The saponification manganese extraction tank is equipped with a manganese extractant addition pipe and a saponification agent addition pipe. The reverse extraction manganese crystallization tank is equipped with a back-extraction agent addition pipe. The COD degradation tank is equipped with a degradation agent addition pipe.

[0047] Preferably, the system also includes a manganese fluoride preparation tank. The outlet of the extract from the defluorination tank is connected to the inlet of the manganese fluoride preparation tank via a water pipeline. The manganese fluoride preparation tank is equipped with a manganese addition mechanism.

[0048] Preferably, the exhaust port of the return tank is connected to the carbon dioxide delivery pipeline via a carbon dioxide circulation pipeline. The ammonia outlet of the ammonia stripping unit is connected to the inlet of the saponifying agent addition pipeline via an ammonia delivery pipeline, and / or the salt outlet of the carbonation reaction tank is connected to the inlet of the saponifying agent addition pipeline via a salt delivery mechanism.

[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] This invention proposes for the first time a technical concept for the resource-based treatment and recovery of carbon powder, fluorite, manganese fluoride, manganese sulfate, potassium bicarbonate, potassium sulfate, and sodium chloride from blast furnace ferromanganese smelting dust. The process flow is as follows: 1) Washing of blast furnace ferromanganese smelting dust: The blast furnace ferromanganese smelting dust is conveyed into a three-stage countercurrent washing system for washing, resulting in washed slag and leaching wastewater (ash washing wastewater). 2) Two-stage flotation recovery of carbon powder and fluorite: The washed slag is first fed into a first-stage flotation reactor for flotation recovery of carbon powder, and then the washed slag after carbon powder recovery is fed into a second-stage flotation reactor for flotation recovery of fluorite, finally yielding flotation slag and flotation water. The flotation water is preferentially recycled for flotation use, and when the salt concentration of the flotation water is high, it enters a COD degradation reaction tank, where hydrogen peroxide or Fenton's reagent is added for oxidation before being disposed of together with the leaching wastewater. 3) Reduction leaching of flotation residue to recover calcium sulfate: Using dilute sulfuric acid and ferrous sulfate solution as a mixed leaching agent, the flotation residue is reduced and leached under acidic conditions to obtain flotation residue leachate and calcium sulfate product. 4) Multi-stage extraction of leachate to recover fluorine and manganese: The flotation residue leachate is sent to the first-stage extraction unit for fluoride extraction and recovery. The obtained fluorine extract is added with manganese powder to recover manganese fluoride product. The fluorine extraction residue is successively subjected to oxidation to remove iron, sulfidation to remove heavy metals, and alkaline saponification, and then enters the second-stage extraction unit for manganese ion extraction. The obtained manganese extract is added with dilute sulfuric acid for back-extraction, and then evaporated and crystallized to recover high-purity manganese sulfate product. The obtained manganese extraction residue is sent to the homogenization and equalization tank of the ash washing wastewater treatment system. 5) Pre-oxidation coupled with reduction to remove impurities from ash washing wastewater: The leached ash washing wastewater and high-salinity flotation water are sent together to the oxidation reaction tank, and then potassium permanganate solution is added for oxidation treatment. Then the oxidized wastewater is sent to the reduction reaction tank, and soluble ferrous salt solution is added for reduction. 6) Low-cost co-purification of reduction wastewater and leaching residue and ammonia resource recycling: The reduced washing wastewater and manganese extraction residue are mixed, and the pH of the mixed solution is adjusted to about 8 using liquid alkali. The precipitate generated during the mixing process is separated into solid and liquid, and the sludge is transported off-site for disposal. The wastewater enters the alkali adjustment reaction tank, and liquid alkali is added to adjust the pH value to 11-12. The wastewater adjusted to strong alkalinity enters the ammonia nitrogen stripping tower or ammonia stripping unit for ammonia nitrogen removal. The removed ammonia nitrogen is recovered as ammonia water and returned to the alkaline saponification step for recycling (alkalinity adjustment). The ammonia-removed wastewater enters the subsequent treatment device.7) Co-production of potassium bicarbonate and potassium sulfate: The ammonia-removed wastewater is fed into an evaporation and concentration unit for concentration. After concentration, the wastewater enters a carbonation reaction tank where carbon dioxide is introduced for carbonation. The carbonated wastewater is then centrifuged to separate potassium bicarbonate and desalination mother liquor. The desalination mother liquor is preferentially returned to the evaporation and concentration section for recycling. When the sulfate concentration in the mother liquor is high, it is fed into a pH adjustment tank for pH adjustment (preferably by adding dilute sulfuric acid to adjust the pH to around 6-7). The adjusted wastewater is then fed into a salt separation system for variable-temperature evaporation to recover potassium sulfate and sodium chloride. Simultaneously, the carbon dioxide generated during pH adjustment is recycled for the carbonation reaction, promoting the precipitation of potassium bicarbonate. The precipitated potassium bicarbonate can be recycled for the alkaline saponification step (alkalinity adjustment).

[0051] In this invention, the dust from blast furnace ferromanganese smelting is the dust generated during ferromanganese smelting using the blast furnace method. It is treated by mixing and washing industrial water with the dust in a certain ratio (e.g., a water-to-ash ratio of 1-7:1). After thorough washing and leaching, the easily soluble substances in the dust are released into the water. The filter residue is returned to sintering or transported for disposal. The resulting wastewater is strongly alkaline (generally pH > 11). The cations in the wastewater mainly include iron, manganese, potassium, sodium, and zinc, while the anions mainly include carbonate, sulfite, sulfate, chloride, fluoride, and hydroxide ions.

[0052] In this invention, the dust from blast furnace ferromanganese smelting contains a significant amount of carbon powder and fluorite. These two substances will not be leached into the aqueous phase by water washing and possess good recovery value, allowing for recovery through a two-stage flotation process. Furthermore, the presence of fluorite poses a risk of increased fluoride ions in the leachate due to subsequent acidic reduction leaching. The carbon powder and fluorite are recovered separately through a two-stage flotation process. Kerosene is used as the collector to achieve carbon powder separation; oleic acid or 731 (oxidized paraffin soap), CM-10, or No. 2 oil are used as collectors, sodium carbonate as a pH adjuster, and water glass as a depressant to achieve fluorite separation.

[0053] In this invention, the flotation residue after two-stage flotation to recover carbon powder and fluorite is subjected to reduction leaching using dilute sulfuric acid and ferrous sulfate (or other soluble salts containing ferrous ions or iron powder) as a mixed leaching agent. The manganese and ferric ions in the flotation residue are leached out in the form of manganese sulfate and ferric sulfate, and most of the remaining calcium ions in the residue form calcium sulfate precipitate with sulfate ions in the leaching agent. In addition, the remaining fluoride ions in the residue are also leached into the liquid phase, which facilitates the subsequent resource recovery of fluoride.

[0054] In this invention, the pH of the reducing leachate from flotation residue is generally around 2-3. Besides manganese sulfate, it mainly contains fluoride ions, calcium, magnesium, iron, aluminum, zinc, etc. The leachate is first defluorinated using an extraction method, specifically using tertiary amine N235 as the fluoride extractant to obtain a fluoride-containing solution. Manganese powder is then added to the fluoride-containing extract to react with the manganese ions, forming manganese fluoride precipitate for recovery. Secondly, the wastewater after fluoride extraction is oxidized by adding hydrogen peroxide or ozone, causing the ferrous iron in the wastewater to convert to ferric iron and precipitate. Simultaneously, a certain amount of sulfides, such as barium sulfide or sodium sulfide, is added to cause the heavy metals in the wastewater to be removed as sulfide precipitates. Finally, the pH of the wastewater after metal ion removal is adjusted to 4-5 by adding ammonia or carbonate (e.g., potassium bicarbonate). At the same time, carboxylic acid, phosphoric acid extractants and kerosene diluent are added for manganese extraction. The manganese extract is then back-extracted with dilute sulfuric acid, and the back-extracted solution is evaporated and crystallized to recover high-purity manganese sulfate.

[0055] In this invention, the pretreatment and impurity removal of ash washing wastewater mainly includes four stages: oxidation, reduction, homogenization, and ammonia removal. ① Oxidation: Analysis shows that ash washing 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 potassium permanganate will not affect the water quality, and the introduced manganese will be removed in the subsequent reduction process. In addition, the oxidation process can also oxidize and treat the flotation water together, further reducing the COD in the flotation water. ② Reduction: Studies have shown that ash washing wastewater after oxidation treatment contains high-valence manganese and iron, which can exist stably in highly alkaline solutions. Reducing ferrous salts can reduce high-valence manganese and iron ions to divalent manganese ions and trivalent iron ions, and then utilize the high alkalinity of the wastewater to achieve deep purification of manganese and iron in the wastewater. ③ Homogenization: Because the ash washing wastewater after oxidation and reduction treatment is alkaline, in addition to sulfate, potassium, sodium, and carbonate ions, it also contains high concentrations of fluoride and zinc ions. The extraction residue wastewater after manganese extraction is acidic and contains a certain concentration of magnesium, aluminum, and zinc ions. Considering the strong complementarity of the two wastewater streams, they are mixed and homogenized, and the pH of the mixed solution is adjusted to around 8. During mixing, fluoride in the washing wastewater undergoes an adsorption reaction with aluminum in the extraction residue, achieving efficient removal. Simultaneously, zinc ions precipitate under this pH condition, and calcium and magnesium in the extraction residue react with carbonate ions in the washing wastewater, resulting in precipitation and removal. ④ Ammonia removal: After initial sedimentation and solid-liquid separation, the homogenized wastewater is further adjusted to a pH of 11-12 using liquid alkali, 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 ammonia nitrogen. The removed ammonia nitrogen is recovered as ammonia water and used as an alkaline regulator for the saponification reaction in the manganese extraction process, realizing the circulation of ammonia in the system.

[0056] In this invention, after pretreatment and ammonia removal, the ash washing wastewater is fed into an evaporation system for concentration. Carbon dioxide is then introduced into the concentrated wastewater to produce potassium bicarbonate. Taking advantage of the lower solubility of potassium bicarbonate compared to potassium carbonate, the potassium bicarbonate is separated and recovered. The recovered mother liquor is tested for sulfate concentration. When the sulfate concentration in the wastewater is below a set value (e.g., 150 g / L), this portion is returned to the evaporation system for further concentration. Conversely, when the sulfate concentration is above the set value (e.g., 150 g / L), dilute sulfuric acid is added to adjust the pH to 6-7. Then, high-value potassium sulfate and sodium chloride products are separated and recovered through variable-temperature evaporation, achieving zero wastewater discharge and resource recovery.

[0057] In this invention, the wastewater after evaporation, concentration, and separation of potassium bicarbonate contains a large amount of carbonate, sulfate, and chloride ions, forming a five-membered phase diagram, making salt separation difficult. Therefore, dilute sulfuric acid is added to adjust the pH of the wastewater to 6-7, causing acid hydrolysis of the carbonate ions. This converts the anions in the wastewater into sulfate and chloride ions, reducing the difficulty of evaporation and salt separation.

[0058] In this invention, pH adjustment achieves the purification of potassium bicarbonate and reduces the difficulty of separating potassium sulfate and sodium chloride. Simultaneously, due to the large amount of carbonate ions in the wastewater, a significant amount of carbon dioxide is generated during the pH adjustment process. This released carbon dioxide is used for the carbonation reaction of potassium carbonate, promoting the precipitation of potassium bicarbonate. This saves production costs and achieves zero emissions of wastewater and waste gas. Furthermore, potassium bicarbonate can also serve as a source of alkaline regulator for the saponification reaction in the manganese extraction process, enabling internal recycling within the system and further reducing production costs.

[0059] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0060] 1. This invention, based on the characteristics of dust from blast furnace ferromanganese smelting, proposes for the first time a technical concept for recovering carbon powder, fluorite, manganese fluoride, manganese sulfate, potassium bicarbonate, potassium sulfate, and sodium chloride from blast furnace ferromanganese smelting dust through water washing. It achieves the synergistic treatment and resource utilization of waste residue and wastewater through water washing, flotation, leaching, multi-stage extraction, oxidation, reduction, deammoniation, and recirculation. The recycling of carbon dioxide through recirculation promotes the recovery of high-purity potassium bicarbonate and significantly reduces the difficulty of obtaining high-value potassium sulfate and sodium chloride products through temperature-controlled evaporation separation. Furthermore, ammonia recycling ensures the efficient and comprehensive utilization of the washed residue.

[0061] 2. This invention is specifically designed for the water quality of ash washing wastewater, enabling the low-cost removal of key pollutants affecting the quality of by-products without introducing impurities or causing secondary pollution. Simultaneously, the separation process for carbonate, sulfate, and chloride ions is optimized, simplifying the complex multi-phase diagram, significantly reducing the difficulty of salt separation, and recovering various high-value salt products while achieving zero emissions of wastewater and exhaust gas.

[0062] 3: This invention addresses the characteristics of water washing slag by employing a specially designed process route to achieve solid-phase recovery of various valuable resources. Simultaneously, the flotation waste liquid and extraction residue generated during the water washing slag treatment process can synergistically participate in the resource utilization process of ash washing wastewater. This achieves organic coupling of multiple process ports within the system, satisfying internal disposal needs while significantly improving the efficiency of internal waste resource utilization, resulting in a technical effect greater than 1+1>2. Attached Figure Description

[0063] Figure 1 This is a flowchart of the method for resource utilization of dust from blast furnace ferromanganese smelting according to the present invention.

[0064] Figure 2 This is a simplified structural diagram of the blast furnace manganese ferrometallurgical dust removal and ash resource utilization system of the present invention.

[0065] Figure 3 This is a schematic diagram of the overall structure of the blast furnace manganese ferrometallurgical dust removal and ash resource utilization system of the present invention.

[0066] Figure labels: 1: Three-stage countercurrent water washing device; 101: Manganese iron ash conveying mechanism; 102: Industrial water conveying pipeline; 2: Oxidation-reduction tank; 201: Potassium permanganate adding mechanism; 202: Ferrous salt adding mechanism; 3: Homogenizing tank; 4: Ammonia stripping device; 401: Liquid alkali adding pipeline; 402: First pH probe; 403: Ammonia conveying pipeline; 5: Evaporation and concentration device; 6: Carbonation reaction tank; 601: Carbon dioxide conveying pipeline; 602: Salt conveying mechanism; 7: First transition tank; 701: Sulfate ion sampling and detection meter; 702: First circulating water pipeline; 8: Adjustment tank; 801: First acid adding mechanism; 802: Second pH probe; 803: Carbon dioxide circulating pipeline; 9: 10: Evaporation and salt separation device; 11: Two-stage flotation device; 12: Reduction leaching tank; 13: Mixed leaching agent addition mechanism; 14: Extraction and defluorination tank; 15: Fluorine extractant addition pipeline; 16: Impurity removal tank; 17: Oxidant addition mechanism; 18: Reducing agent addition mechanism; 19: Saponification and manganese extraction tank; 10: Manganese extractant addition pipeline; 11: Saponification agent addition pipeline; 12: Reverse extraction and crystallization tank; 13: Back-extractant addition pipeline; 14: Second transition tank; 15: Salt concentration detector; 16: Second circulating water pipeline; 17: COD degradation tank; 18: Degradant addition pipeline; 19: Manganese fluoride preparation tank; 10: Manganese addition mechanism. Detailed Implementation

[0067] 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.

[0068] A system for the resource utilization of dust from blast furnace ferromanganese smelting includes a three-stage countercurrent water washing device 1, a wastewater treatment unit for ash washing, and a slag washing treatment unit. The wastewater treatment unit comprises, in series, an oxidation-reduction tank 2, a homogenization tank 3, an ammonia stripping device 4, an evaporation and concentration device 5, a carbonation reaction tank 6, a first transition tank 7, a return tank 8, and an evaporation and salt separation device 9. The slag washing treatment unit comprises, in series, a two-stage flotation device 10, a reduction leaching tank 11, an extraction and defluorination tank 12, an impurity removal tank 13, a saponification and manganese extraction tank 14, and a reverse extraction and crystallization tank 15.

[0069] Preferably, the ash inlet of the three-stage countercurrent washing device 1 is connected to a manganese iron ash conveying mechanism 101, and its water inlet is connected to an industrial water conveying pipeline 102. The drain outlet of the three-stage countercurrent washing device 1 is connected to the water inlet of the oxidation-reduction tank 2 through a water conveying pipeline, and its slag discharge outlet is connected to the two-stage flotation device 10 through a slag conveying mechanism.

[0070] Preferably, the inlet of the carbonation reaction tank 6 is connected to a carbon dioxide delivery pipe 601. A sulfate ion detector 701 is installed in the first transition tank 7, and its outlet is connected to the inlet of the evaporation and concentration device 5 via a first circulating water pipe 702. The residual liquid outlet of the saponification manganese extraction tank 14 is connected to the inlet of the homogenization tank 3 via a water delivery pipe.

[0071] Preferably, the system also includes a second transition tank 16 and a COD degradation tank 17. The drain outlets of the two flotation devices 10 are connected to the inlet of the second transition tank 16 via water supply pipes. The drain outlet of the second transition tank 16 is connected to the inlet of the COD degradation tank 17 via water supply pipes. The drain outlet of the COD degradation tank 17 is connected to the inlet of the oxidation-reduction tank 2 via water supply pipes. A salt concentration detector 1601 is installed in the second transition tank 16. The drain outlet of the second transition tank 16 is also connected to the inlet of the two flotation devices 10 via a second circulating water supply pipe 1602.

[0072] Preferably, the redox tank 2 is equipped with a potassium permanganate addition mechanism 201 and a ferrous salt addition mechanism 202. The ammonia stripping device 4 is connected to a liquid alkali addition pipe 401, which contains a first pH probe 402. The setback tank 8 is equipped with a first acid addition mechanism 801, which contains a second pH probe 802.

[0073] Preferably, the reduction leaching tank 11 is equipped with a mixed leaching agent addition mechanism 1101. The extraction and defluorination tank 12 is equipped with a fluorine extractant addition pipe 1201. The impurity removal tank 13 is equipped with an oxidant addition mechanism 1301 and a reducing agent addition mechanism 1302. The saponification manganese extraction tank 14 is equipped with a manganese extractant addition pipe 1401 and a saponification agent addition pipe 1402. The reverse extraction manganese crystallization tank 15 is equipped with a back-extraction agent addition pipe 1501. The COD degradation tank 17 is equipped with a degradation agent addition pipe 1701.

[0074] Preferably, the system also includes a manganese fluoride preparation tank 18. The extract outlet of the extraction and defluorination tank 12 is connected to the inlet of the manganese fluoride preparation tank 18 via a water supply pipe. The manganese fluoride preparation tank 18 is equipped with a manganese addition mechanism 1801.

[0075] Preferably, the exhaust port of the return tank 8 is connected to the carbon dioxide conveying pipe 601 via the carbon dioxide circulation pipe 803. The ammonia outlet of the ammonia stripping device 4 is connected to the inlet of the saponifying agent addition pipe 1402 via the ammonia conveying pipe 403 and / or the salt outlet of the carbonation reaction tank 6 is connected to the inlet of the saponifying agent addition pipe 1402 via the salt conveying mechanism 602.

[0076] Example 1

[0077] like Figure 2-3 As shown, a system for the resource utilization of dust from blast furnace ferromanganese smelting includes a three-stage countercurrent water washing device 1, a wastewater treatment unit for ash washing, and a slag washing treatment unit. The wastewater treatment unit includes, in series, an oxidation-reduction tank 2, a homogenization tank 3, an ammonia stripping device 4, an evaporation and concentration device 5, a carbonation reaction tank 6, a first transition tank 7, a return tank 8, and an evaporation and salt separation device 9. The slag washing treatment unit includes, in series, a two-stage flotation device 10, a reduction leaching tank 11, an extraction and defluorination tank 12, an impurity removal tank 13, a saponification and manganese extraction tank 14, and a reverse extraction and crystallization tank 15.

[0078] Example 2

[0079] The embodiment 1 is repeated, except that the ash inlet of the three-stage countercurrent washing device 1 is connected to the manganese iron ash conveying mechanism 101, and its water inlet is connected to the industrial water conveying pipeline 102. The drain outlet of the three-stage countercurrent washing device 1 is connected to the water inlet of the oxidation-reduction tank 2 through a water conveying pipeline, and its slag discharge outlet is connected to the two-stage flotation device 10 through a slag conveying mechanism.

[0080] Example 3

[0081] Example 2 is repeated, except that the inlet of the carbonation reaction tank 6 is connected to a carbon dioxide delivery pipe 601. A sulfate ion detector 701 is installed in the first transition tank 7, and its outlet is connected to the inlet of the evaporation and concentration device 5 via a first circulating water pipe 702. The residual liquid outlet of the saponification manganese extraction tank 14 is connected to the inlet of the homogenization tank 3 via a water delivery pipe.

[0082] Example 4

[0083] The system repeats Example 3, except that it also includes a second transition tank 16 and a COD degradation tank 17. The outlets of the two flotation units 10 are connected to the inlet of the second transition tank 16 via water supply pipes. The outlet of the second transition tank 16 is connected to the inlet of the COD degradation tank 17 via water supply pipes. The outlet of the COD degradation tank 17 is connected to the inlet of the oxidation-reduction tank 2 via water supply pipes. A salt concentration detector 1601 is installed in the second transition tank 16. The outlet of the second transition tank 16 is also connected to the inlet of the two flotation units 10 via a second circulating water supply pipe 1602.

[0084] Example 5

[0085] Example 4 is repeated, except that the redox tank 2 is equipped with a potassium permanganate addition mechanism 201 and a ferrous salt addition mechanism 202. The ammonia stripping device 4 is connected to a liquid alkali addition pipe 401, which is equipped with a first pH probe 402. The setback tank 8 is equipped with a first acid addition mechanism 801, which is equipped with a second pH probe 802.

[0086] Example 6

[0087] Example 5 is repeated, except that a mixed leaching agent addition mechanism 1101 is provided on the reduction leaching tank 11. A fluorine extractant addition pipe 1201 is provided on the extraction defluorination tank 12. An oxidant addition mechanism 1301 and a reducing agent addition mechanism 1302 are provided on the impurity removal tank 13. A manganese extractant addition pipe 1401 and a saponification agent addition pipe 1402 are provided on the saponification manganese extraction tank 14. A back-extraction agent addition pipe 1501 is provided on the reverse extraction manganese crystallization tank 15. A degradation agent addition pipe 1701 is provided on the COD degradation tank 17.

[0088] Example 7

[0089] The system repeats Example 6, except that it also includes a manganese fluoride preparation tank 18. The outlet of the extract from the defluorination tank 12 is connected to the inlet of the manganese fluoride preparation tank 18 via a water pipeline. The manganese fluoride preparation tank 18 is equipped with a manganese addition mechanism 1801.

[0090] Example 8

[0091] Example 7 is repeated, except that the exhaust port of the return tank 8 is connected to the carbon dioxide conveying pipe 601 via the carbon dioxide circulation pipe 803. The ammonia outlet of the ammonia stripping device 4 is connected to the inlet of the saponifying agent addition pipe 1402 via the ammonia conveying pipe 403, and the salt outlet of the carbonation reaction tank 6 is connected to the inlet of the saponifying agent addition pipe 1402 via the salt conveying mechanism 602.

[0092] Example 9

[0093] A method for resource utilization of dust from blast furnace ferromanganese smelting, the method comprising the following steps:

[0094] 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.

[0095] 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. The flotation water is divided into high-salt flotation water and low-salt flotation water based on whether the salt concentration exceeds a set value. The low-salt flotation water is recycled for flotation of the washed residue, while the high-salt flotation water undergoes COD degradation treatment before entering the wastewater pretreatment process.

[0096] 3) Wastewater pretreatment: The ash washing wastewater obtained in step 1) is mixed with the high-salt flotation water obtained after COD degradation in step 2) to obtain mixed wastewater. An oxidant is first added to the mixed wastewater for oxidation treatment. Then, a reducing agent is added to the oxidized wastewater for reduction treatment. After solid-liquid separation, pretreated wastewater is obtained.

[0097] 4) Reduction leaching: Dilute sulfuric acid and ferrous salt are used as leaching agents to leach the flotation residue obtained in step 2). After leaching, solid-liquid separation is performed to obtain calcium sulfate product and leaching solution.

[0098] 5) Multi-stage extraction: First, the leachate obtained in step 4) is extracted using a fluorine extractant to obtain a fluorine extract and a primary extraction residue. Manganese powder is added to the fluorine extract to prepare manganese fluoride. Then, the primary extraction residue is sequentially treated with oxidation to remove iron, sulfidation to remove heavy metals, and saponification before being extracted with a manganese extractant to obtain a manganese extract and a secondary extraction residue. Dilute sulfuric acid is added to the manganese extract for back-extraction and evaporation crystallization to obtain manganese sulfate. Finally, the secondary extraction residue is homogenized with the pretreated wastewater obtained in step 3), and after solid-liquid separation, sludge and a mixed clear liquid are obtained. The sludge is transported for disposal, and the mixed clear liquid enters the alkali adjustment and ammonia removal step.

[0099] 6) Alkalinity Adjustment and Ammonia Removal: First, adjust the mixed clear liquid obtained in step 5) to a weakly alkaline state using alkali to precipitate and remove zinc. Then, adjust the zinc-removed wastewater to a strongly alkaline state using alkali and send it to the ammonia removal unit for ammonia removal treatment, obtaining ammonia-removed wastewater for the next process.

[0100] 7) Concentration to produce potassium bicarbonate: The ammonia-removing wastewater obtained in step 6) is concentrated, and then carbon dioxide is introduced into the concentrated wastewater to carry out a carbonation reaction. After solid-liquid separation, high-purity potassium bicarbonate and desalination mother liquor are obtained.

[0101] 8) Circulating evaporation and salt separation: Based on whether the sulfate ion concentration in the desalination mother liquor exceeds the set sulfate concentration value, the desalination mother liquor is divided into high-sulfur mother liquor and low-sulfur mother liquor. The low-sulfur mother liquor is returned and combined with the ammonia removal wastewater for step 7). The high-sulfur mother liquor is adjusted to neutral by adding acid, and then high-purity potassium sulfate and sodium chloride are recovered through temperature-controlled evaporation and salt separation.

[0102] Example 10

[0103] A method for resource utilization of dust from blast furnace ferromanganese smelting, the method comprising the following steps:

[0104] 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.

[0105] 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. The flotation water is divided into high-salt flotation water and low-salt flotation water based on whether the salt concentration exceeds a set value. The low-salt flotation water is recycled for flotation of the washed residue, while the high-salt flotation water undergoes COD degradation treatment before entering the wastewater pretreatment process.

[0106] 3) Wastewater pretreatment: The ash washing wastewater obtained in step 1) is mixed with the high-salt flotation water obtained after COD degradation in step 2) to obtain mixed wastewater. An oxidant is first added to the mixed wastewater for oxidation treatment. Then, a reducing agent is added to the oxidized wastewater for reduction treatment. After solid-liquid separation, pretreated wastewater is obtained.

[0107] 4) Reduction leaching: Dilute sulfuric acid and ferrous salt are used as leaching agents to leach the flotation residue obtained in step 2). After leaching, solid-liquid separation is performed to obtain calcium sulfate product and leaching solution.

[0108] 5) Multi-stage extraction: First, the leachate obtained in step 4) is extracted using a fluorine extractant to obtain a fluorine extract and a primary extraction residue. Manganese powder is added to the fluorine extract to prepare manganese fluoride. Then, the primary extraction residue is sequentially treated with oxidation to remove iron, sulfidation to remove heavy metals, and saponification before being extracted with a manganese extractant to obtain a manganese extract and a secondary extraction residue. Dilute sulfuric acid is added to the manganese extract for back-extraction and evaporation crystallization to obtain manganese sulfate. Finally, the secondary extraction residue is homogenized with the pretreated wastewater obtained in step 3), and after solid-liquid separation, sludge and a mixed clear liquid are obtained. The sludge is transported for disposal, and the mixed clear liquid enters the alkali adjustment and ammonia removal step.

[0109] 6) Alkalinity Adjustment and Ammonia Removal: First, adjust the mixed clear liquid obtained in step 5) to a weakly alkaline state using alkali to precipitate and remove zinc. Then, adjust the zinc-removed wastewater to a strongly alkaline state using alkali and send it to the ammonia removal unit for ammonia removal treatment, obtaining ammonia-removed wastewater for the next process.

[0110] 7) Concentration to produce potassium bicarbonate: The ammonia-removing wastewater obtained in step 6) is concentrated, and then carbon dioxide is introduced into the concentrated wastewater to carry out a carbonation reaction. After solid-liquid separation, high-purity potassium bicarbonate and desalination mother liquor are obtained.

[0111] 8) Circulating evaporation and salt separation: Based on whether the sulfate ion concentration in the desalination mother liquor exceeds the set sulfate concentration value, the desalination mother liquor is divided into high-sulfur mother liquor and low-sulfur mother liquor. The low-sulfur mother liquor is returned and combined with the ammonia removal wastewater for step 7). The high-sulfur mother liquor is adjusted to neutral by adding acid, and then high-purity potassium sulfate and sodium chloride are recovered through temperature-controlled evaporation and salt separation.

[0112] Preferably, the method further includes the following steps:

[0113] 9) The carbon dioxide generated during the process of adding acid to adjust the high-sulfur mother liquor to neutrality in step 8) is recycled to step 7) for carbonation reaction. The ammonia gas removed in step 6) is recovered as ammonia water and recycled to step 5) for saponification treatment, and the potassium bicarbonate obtained in step 7) is used in step 5) for saponification treatment.

[0114] Example 11

[0115] Repeat Example 10, except that in step 2), the salt concentration is set to 100 g / L.

[0116] Example 12

[0117] Repeat Example 11, except that in step 3), the oxidizing agent is potassium permanganate solution.

[0118] Example 13

[0119] Repeat Example 12, except that in step 3), the reducing agent is a ferrous sulfate solution.

[0120] Example 14

[0121] Repeat Example 13, except that in step 4), the ferrous salt is ferrous sulfate.

[0122] Example 15

[0123] Repeat Example 14, except that in step 5), the base is sodium hydroxide.

[0124] Example 16

[0125] Repeat Example 15, except that in step 6), the ammonia removal device is an ammonia stripping device.

[0126] Example 17

[0127] Repeat Example 16, except that in step 8), the sulfate ion concentration is set to 150 g / L.

[0128] Application Example 1

[0129] The dust generated during blast furnace ferromanganese smelting using the system described in Example 8 and the method described in Example 17 will be recycled. The specific process is as follows:

[0130] The dust from blast furnace ferromanganese smelting was subjected to a three-stage water washing and leaching process using industrial water at a water-to-ash ratio of 1:6.5. The resulting ash was then filtered to obtain washed slag and washing wastewater (pH > 11). Kerosene was used as a flotation agent (0.3% of the washed slag mass) to float the slag in a primary flotation reactor to obtain carbon powder. Then, oleic acid was used as a collector (600 g / t), sodium carbonate as a pH adjuster (to adjust pH to 9), and water glass as a depressant (2000 g / t) to float the decarbonized washed slag in a secondary flotation reactor to obtain fluorite. The salt concentration in the flotation wastewater was found to be approximately 19 g / L; this portion of the wastewater was recycled for further flotation in the two-stage flotation process.

[0131] 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 leach the flotation residue after two stages of flotation for 45 min. After leaching, solid-liquid separation was performed to obtain calcium sulfate product and leaching solution. Then, tertiary amine N235 was used as a fluorine extractant (3 times the volume of leaching solution) to extract the leaching solution for 20 min, obtaining a fluorine-containing extract and a primary extraction residue. Manganese powder was added to the separated fluorine-containing extract to react, and after solid-liquid separation, manganese fluoride product (purity 98.6%) was obtained. Finally, hydrogen peroxide (3.5% of the mass of the primary extraction residue) was added to the primary extraction residue for oxidation treatment for 10 min, barium sulfide (0.4% of the mass of the primary extraction residue) was added for precipitation treatment for 10 min, and ammonia was added to adjust the pH of the leaching solution 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 10 min to obtain a manganese-containing extract and a secondary extraction residue. Dilute sulfuric acid was added to the manganese-containing extract at a ratio of 1:3 for back-extraction for 10 min, and the manganese-containing back-extraction was evaporated, concentrated, and crystallized to obtain manganese sulfate product (purity of 99.4%).

[0132] Add 5% (by weight of the total ash washing wastewater) of a 25% potassium permanganate solution to the ash washing wastewater and stir for 30 minutes for oxidation treatment. Then add 7% (by weight of the total ash washing wastewater) of a 20% ferrous sulfate solution to the oxidized wastewater and stir for reduction treatment for 30 minutes. After the treatment is completed, perform solid-liquid separation to obtain pretreated wastewater.

[0133] The pretreated wastewater is mixed with the secondary extraction residue, and then sodium hydroxide solution is added to the mixed wastewater to adjust the pH of the mixed wastewater to 8 (maintain this state) for precipitation treatment for 15 minutes. Then, sodium hydroxide solution is added to the supernatant to adjust the pH of the supernatant to 12, and the supernatant adjusted to strong alkalinity is sent to the ammonia stripping unit for ammonia removal treatment to obtain ammonia water (recycled for chemical treatment) and ammonia-removed wastewater.

[0134] The ammonia removal wastewater was concentrated until the potassium carbonate concentration in the solution reached approximately 310 g / L. Then, carbon dioxide was introduced into the concentrated wastewater to initiate a carbonation reaction for 1.5 hours. After the reaction, solid-liquid separation was performed to obtain high-purity potassium bicarbonate (99.20% purity, which can be recycled to the saponification process as an alkali adjuster) and desalination mother liquor. The concentration of sulfate ions in the desalination mother liquor was detected to be 86.12 g / L. This desalination mother liquor was then returned to be mixed with the impurity removal wastewater for further concentration and recycling. Simultaneously, the carbon dioxide generated during the alkali adjustment of the pretreated wastewater was used in the carbonation reaction of the concentrated wastewater. In this embodiment, the entire process produces no wastewater or exhaust gas emissions.

[0135] Application Example 2

[0136] The dust generated during blast furnace ferromanganese smelting using the system described in Example 8 and the method described in Example 17 will be recycled. The specific process is as follows:

[0137] The dust from blast furnace ferromanganese smelting was subjected to a three-stage water washing and leaching process using industrial water at a water-to-ash ratio of 1:5.5. The resulting ash was then filtered to obtain washed slag and washing wastewater (pH > 11). Kerosene was used as a flotation agent (0.35% of the washed slag mass) to float the slag in a primary flotation reactor to obtain carbon powder. Then, oleic acid was used as a collector (600 g / t), sodium carbonate as a pH adjuster (to adjust pH to 9), and water glass as a depressant (2000 g / t) to float the decarbonized washed slag in a secondary flotation reactor to obtain fluorite. The salt concentration in the flotation wastewater was found to be approximately 115 g / L. This portion of the flotation wastewater was mixed with the washing wastewater and subjected to oxidation treatment.

[0138] 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 leach the flotation residue after two stages of flotation for 45 min. After leaching, solid-liquid separation was performed to obtain calcium sulfate product and leaching solution. Then, tertiary amine N235 was used as a fluorine extractant (3 times the volume of leaching solution) to extract the leaching solution for 20 min, obtaining a fluorine-containing extract and a primary extraction residue. Manganese powder was added to the separated fluorine-containing extract to react, and after solid-liquid separation, manganese fluoride product (purity 97.7%) was obtained. Finally, hydrogen peroxide (4% of the mass of the primary extraction residue) was added to the primary extraction residue for oxidation treatment for 10 min, barium sulfide (0.45% of the mass of the primary extraction residue) was added for precipitation treatment for 10 min, and ammonia was added to adjust the pH of the leaching solution 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 10 min to obtain a manganese-containing extract and a secondary extraction residue. Dilute sulfuric acid was added to the manganese-containing extract at a ratio of 1:3 for back-extraction for 10 min, and the manganese-containing back-extraction was evaporated, concentrated, and crystallized to obtain manganese sulfate product (purity of 99.60%).

[0139] After mixing flotation wastewater and ash washing wastewater, add 5% (by weight of the total mixed wastewater) of a 25% potassium permanganate solution and stir for oxidation treatment for 30 minutes. Then, add 7% (by weight of the total ash washing wastewater) of a 20% ferrous sulfate solution to the oxidized wastewater and stir for reduction treatment for 30 minutes. After the treatment is completed, perform solid-liquid separation to obtain pretreated wastewater.

[0140] The pretreated wastewater is mixed with the secondary extraction residue, and then sodium hydroxide solution is added to the mixed wastewater to adjust the pH of the mixed wastewater to 8 (maintain this state) for precipitation treatment for 15 minutes. Then, sodium hydroxide solution is added to the supernatant to adjust the pH of the supernatant to 12, and the supernatant adjusted to strong alkalinity is sent to the ammonia stripping unit for ammonia removal treatment to obtain ammonia water (recycled for chemical treatment) and ammonia-removed wastewater.

[0141] The ammonia removal wastewater was concentrated until the potassium carbonate concentration in the solution reached approximately 300 g / L. Carbon dioxide was then introduced into the concentrated wastewater to initiate a carbonation reaction for 2 hours. After the reaction, solid-liquid separation was performed to obtain high-purity potassium bicarbonate (99.35% purity, which can be recycled for saponification as an alkali adjuster) and desalination mother liquor. The sulfate ion concentration in the desalination mother liquor was detected to be 190.9 g / L. Dilute sulfuric acid was added to adjust the pH of the desalination mother liquor to 6.5. The neutralized desalination mother liquor was then evaporated and desalinated to obtain potassium sulfate (90.70% purity) and sodium chloride (92.51% purity). Simultaneously, the carbon dioxide generated during the neutralization process of the desalination mother liquor was used for the carbonation reaction of the concentrated wastewater. This entire process produced no wastewater or exhaust gas emissions.

Claims

1. A method for resource utilization of dust collected in smelting of blast furnace ferromanganese, characterized in that: The method includes the following steps: 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. 2) Flotation: The water-washed residue obtained in step 1) is subjected to two-stage flotation to recover carbon powder and fluorite respectively, and flotation residue and flotation water are obtained. The flotation water is divided into high-salt flotation water and low-salt flotation water according to whether the salt concentration in the flotation water exceeds the set salt concentration value. The low-salt flotation water is recycled to participate in the flotation of the water-washed residue, while the high-salt flotation water is treated for COD degradation and then enters the wastewater pretreatment. 3) Wastewater pretreatment: The ash washing wastewater obtained in step 1) is mixed with the high-salt flotation water after COD degradation obtained in step 2) to obtain mixed wastewater; first, an oxidant is added to the mixed wastewater for oxidation treatment; then, a reducing agent is added to the oxidized wastewater for reduction treatment, and the pretreated wastewater is obtained after solid-liquid separation. 4) Reduction leaching: Dilute sulfuric acid and ferrous salt are used as leaching agents to leach the flotation residue obtained in step 2). After leaching, solid-liquid separation is performed to obtain calcium sulfate product and leaching solution. 5) Multi-stage extraction: First, the leaching solution obtained in step 4) is extracted with a fluorine extractant to obtain a fluorine extract and a primary extraction residue; manganese powder is added to the fluorine extract to prepare manganese fluoride product; then, the primary extraction residue is successively subjected to oxidation to remove iron, sulfidation to remove heavy metals, and saponification treatment, and then extracted with a manganese extractant to obtain a manganese extract and a secondary extraction residue; dilute sulfuric acid is added to the manganese extract for back-extraction and evaporation crystallization treatment to obtain manganese sulfate product; finally, the secondary extraction residue is homogenized with the pretreated wastewater obtained in step 3), and after solid-liquid separation, sludge and mixed clear liquid are obtained. The sludge is transported off-site for disposal, and the mixed clear liquid enters the alkali adjustment and ammonia removal step; 6) Alkalinity adjustment and ammonia removal: First, adjust the mixed clear liquid obtained in step 5) to weak alkalinity with alkali to precipitate and remove zinc; then adjust the zinc-removed wastewater to strong alkalinity with alkali and send it to the ammonia removal device for ammonia removal treatment to obtain ammonia-removed wastewater for the next process. 7) Concentration to produce potassium bicarbonate: The ammonia-removing wastewater obtained in step 6) is concentrated, and then carbon dioxide is introduced into the concentrated wastewater to carry out a carbonation reaction. After solid-liquid separation, high-purity potassium bicarbonate and desalination mother liquor are obtained. 8) Circulating evaporation and salt separation: Based on whether the sulfate ion concentration in the desalination mother liquor exceeds the set value of sulfate concentration, the desalination mother liquor is divided into high-sulfur mother liquor and low-sulfur mother liquor; the low-sulfur mother liquor is returned and combined with the ammonia removal wastewater for step 7); the high-sulfur mother liquor is adjusted to neutral by adding acid, and then high-purity potassium sulfate and sodium chloride are recovered by temperature-variable evaporation and salt separation.

2. The method of claim 1, wherein: The method also includes the following steps: 9) The carbon dioxide generated during the process of adding acid to adjust the high-sulfur mother liquor to neutrality in step 8) is recycled to step 7) for carbonation reaction; the ammonia gas removed in step 6) is recovered as ammonia water and recycled to step 5) to participate in saponification treatment and / or the potassium bicarbonate obtained in step 7) is used in step 5) to participate in saponification treatment.

3. The method according to claim 1 or 2, characterized in that: The dust collected during blast furnace ferromanganese smelting is dust containing iron, manganese, fluorine, alkali metals, carbonate, and sulfite generated during blast furnace ferromanganese smelting.

4. The method of claim 1 or 2, wherein: In step 1), the water washing is a three-stage countercurrent water washing; the water-to-ash ratio during water washing is 1-7:1; The ash washing wastewater is a highly alkaline wastewater.

5. The method of claim 4, wherein: In step 1), the water-to-cement ratio during washing is 2-5:1; The ash washing wastewater has a pH > 11.

6. The method of claim 1 or 2, wherein: In step 2), the flotation agent used for recovering carbon powder is kerosene, and its dosage is 0.1-0.8% of the raw material mass. The collector used in the flotation recovery of fluorite is one of oleic acid, oxidized paraffin soap, CM-10, or No. 2 oil, with a dosage of 500-1000 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 1800-2500 g / t.

7. The method of claim 6, wherein: In step 2), the amount of flotation agent added during the flotation recovery of carbon powder is 0.2-0.5% of the raw material mass; The collector dosage for flotation recovery of fluorite is 600-800 g / t; the pH value is adjusted to 9-10; and the inhibitor dosage is 2000-2400 g / t.

8. The method of claim 1 or 2, wherein: The salt concentration is set at 80-120 g / L; and / or The COD degradation treatment specifically involves oxidation using hydrogen peroxide or Fenton's reagent.

9. The method of claim 6, wherein: The salt concentration is set at 90-110 g / L.

10. The method of claim 1 or 2, wherein: In step 3), the oxidant is a potassium permanganate solution; the concentration of the potassium permanganate solution is 15-40%; and / or In step 3), the reducing agent is a soluble ferrous salt solution; the concentration of the soluble ferrous salt solution is 10-30%.

11. The method according to claim 10, characterized in that: In step 3), the concentration of the potassium permanganate solution is 20-30%; and / or In step 3), the concentration of the soluble ferrous salt solution is 15-25%.

12. The method of claim 10, wherein: The amount of oxidant added is 2-8% of the total mass of wastewater; the oxidation treatment time is 5-50 min; and / or The soluble ferrous salt is ferrous sulfate and / or ferrous chloride; the amount of reducing agent added is 3-9% of the total mass of wastewater; the reduction treatment time is 5-50 min.

13. The method of claim 12, wherein: The amount of oxidant added is 3-5% of the total mass of wastewater; the oxidation treatment time is 10-30 min; and / or The amount of reducing agent added is 4-6% of the total mass of wastewater; the reduction treatment time is 10-30 minutes.

14. The method of claim 1 or 2, wherein: In step 4), the ferrous salt is one of ferrous chloride and ferrous sulfate; and / or The pH of the extract is 1-4.

15. The method of claim 14, wherein: In step 4), the pH of the extract is 2-3.

16. The method of claim 1 or 2, wherein: In step 5), the fluorine extractant is tertiary amine N235, and its amount is 2-5 times the total volume of the leaching solution; the extraction time is 5-30 min; and / or In step 5), the iron removal by oxidation is performed using hydrogen peroxide or ozone, with an addition amount of 0.5-5% of the mass of the primary extraction residue; the weight removal by sulfidation is performed using one or more of barium sulfide, sodium sulfide, and hydrogen sulfide, with an addition amount of 0.2-0.8% of the mass of the primary extraction residue; and the saponification treatment is performed by adjusting the pH of the primary extraction residue to 3.5-5.5 using ammonia and / or potassium bicarbonate.

17. The method of claim 16, wherein: In step 5), the amount of fluorine extractant used is 2-4 times the total volume of the leaching solution; the extraction time is 10-20 min; and / or In step 5), the amount of iron removal by oxidation is 0.8-4% of the mass of the primary extraction residue; the amount of weight removal by sulfidation is 0.3-0.5% of the mass of the primary extraction residue; and the saponification treatment involves adjusting the pH of the primary extraction residue to 4-5 using ammonia and / or potassium bicarbonate.

18. The method according to claim 1 or 2, characterized in that: In step 5), 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; the saponification rate of the extractant is 30-65%; and / or In step 5), 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 is 8-20 min.

19. The method of claim 18, wherein: In step 5), the extraction ratio is 2-3:1; the extraction time is 8-15 min; the saponification rate of the extractant is 35-60%; and / or In step 5), 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 is 10-15 min.

20. The method of claim 1 or 2, wherein: In step 6), the alkali is sodium hydroxide and / or potassium hydroxide; adjusting to weak alkalinity means adjusting the pH of the wastewater to 7.5-8.5; adjusting to strong alkalinity means adjusting the pH of the wastewater to greater than 10.

21. The method of claim 20, wherein: In step 6), adjusting to weak alkalinity means adjusting the pH of the wastewater to 7.8-8.3; adjusting to strong alkalinity means adjusting the pH of the wastewater to 11-12.

22. The method of claim 1 or 2, wherein: The ammonia removal device is a stripping tower or an ammonia stripping device.

23. The method of claim 1 or 2, wherein: In step 7), the concentration factor of the ammonia removal wastewater is 2-7 times; and / or In step 8), the sulfate concentration is set to 130-180 g / L; and / or In step 8), the addition of acid to adjust to neutral specifically involves adding dilute sulfuric acid to adjust the pH of the wastewater to 6-7.

24. The method of claim 23, wherein: In step 7), the concentration factor of the ammonia removal wastewater is 3-5 times; and / or In step 8), the sulfate concentration is set to 140-160 g / L; and / or In step 8), the addition of acid to adjust to neutral specifically involves adding dilute sulfuric acid to adjust the pH of the wastewater to 6.5-7.

25. A system for use in the method of any one of claims 1-24, characterized by: The system includes a three-stage countercurrent water washing device (1), a ash washing wastewater treatment unit, and a water washing slag treatment unit; the ash wastewater treatment unit includes an oxidation-reduction tank (2), a homogenization tank (3), an ammonia stripping device (4), an evaporation and concentration device (5), a carbonation reaction tank (6), a first transition tank (7), a return tank (8), and an evaporation and salt separation device (9) arranged in series; the water washing slag treatment unit includes a two-stage flotation device (10), a reduction leaching tank (11), an extraction and defluorination tank (12), a purification tank (13), a saponification and manganese extraction tank (14), and a reverse extraction and manganese crystallization tank (15) arranged in series. The ash inlet of the three-stage countercurrent washing device (1) is connected to the manganese iron ash conveying mechanism (101), and its water inlet is connected to the industrial water conveying pipeline (102); the drain outlet of the three-stage countercurrent washing device (1) is connected to the water inlet of the oxidation-reduction tank (2) through the water conveying pipeline, and its slag outlet is connected to the two-stage flotation device (10) through the slag conveying mechanism. The inlet of the carbonation reaction tank (6) is connected to a carbon dioxide delivery pipe (601); the first transition tank (7) is equipped with a sulfate ion sampling and detection meter (701), and its outlet is connected to the inlet of the evaporation and concentration device (5) through the first circulating water pipeline (702); the residual liquid outlet of the saponification manganese extraction tank (14) is connected to the inlet of the homogenization tank (3) through a water delivery pipe.

26. The system of claim 25, wherein: The system also includes a second transition tank (16) and a COD degradation tank (17); the outlets of the two flotation devices (10) are connected to the inlet of the second transition tank (16) via water supply pipes, the outlets of the second transition tank (16) are connected to the inlet of the COD degradation tank (17) via water supply pipes, and the outlets of the COD degradation tank (17) are connected to the inlet of the oxidation-reduction tank (2) via water supply pipes; a salt concentration detector (1601) is installed in the second transition tank (16), and the outlet of the second transition tank (16) is also connected to the inlet of the two flotation devices (10) via a second circulating water supply pipe (1602).

27. The system according to claim 25 or 26, characterized in that: The oxidation-reduction tank (2) is equipped with a potassium permanganate addition mechanism (201) and a ferrous salt addition mechanism (202); the ammonia stripping device (4) is connected to a liquid alkali addition pipe (401), which is equipped with a first pH probe (402); the setback tank (8) is equipped with a first acid addition mechanism (801), which is equipped with a second pH probe (802); and / or The reduction leaching tank (11) is equipped with a mixed leaching agent addition mechanism (1101); the extraction defluorination tank (12) is equipped with a fluorine extractant addition pipe (1201); the impurity removal tank (13) is equipped with an oxidant addition mechanism (1301) and a reducing agent addition mechanism (1302); the saponification manganese extraction tank (14) is equipped with a manganese extractant addition pipe (1401) and a saponification agent addition pipe (1402); the reverse extraction manganese crystallization tank (15) is equipped with a reverse extractant addition pipe (1501); and the COD degradation tank (17) is equipped with a degradation agent addition pipe (1701).

28. The system of claim 27, wherein: The system also includes a manganese fluoride preparation tank (18); the extract outlet of the extraction defluorination tank (12) is connected to the inlet of the manganese fluoride preparation tank (18) through a water supply pipe; and a manganese addition mechanism (1801) is provided on the manganese fluoride preparation tank (18).

29. The system of claim 28, wherein: The exhaust port of the return tank (8) is connected to the carbon dioxide conveying pipe (601) through the carbon dioxide circulation pipe (803); the ammonia water outlet of the ammonia stripping device (4) is connected to the inlet of the saponifying agent addition pipe (1402) through the ammonia conveying pipe (403) and / or the salt outlet of the carbonation reaction tank (6) is connected to the inlet of the saponifying agent addition pipe (1402) through the salt conveying mechanism (602).

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