Method for compounding and activating inert zinc ferrite in steelmaking furnace dust through calcification-chlorination of waste incineration fly ash and volatilizing and enriching zinc, lead, potassium and sodium

Abstract

The invention relates to the technical field of harmless disposal of hazardous wastes and comprehensive utilization of resources, in particular to a method for activating inert zinc ferrite in steel-making furnace dust through calcification-chlorination of waste incineration fly ash and volatilizing and enriching zinc, lead, potassium and sodium, which comprises the following steps: S100, carrying out raw material compatibility according to mineral phase composition of the waste incineration fly ash and the steel-making furnace dust to obtain a mixture; s200, the obtained mixture is supplemented with inert gas flow, and the mixture is fed into a high-temperature area to be roasted; s300, after calcification-chlorination composite activation high-temperature roasting, an activated phase rich in zinc, lead, potassium and sodium is generated and brought into a low-temperature area by airflow for desublimation and enrichment; and S400, the obtained enriched phase is subjected to step-by-step deposition enrichment, and zinc, lead and potassium sodium enriched products are obtained. In order to solve the problems that the zinc-containing steel-making furnace dust is difficult to utilize and the generation amount of the waste incineration fly ash is gradually increased over years, the method is provided for activating inert-phase zinc ferrite in the zinc-containing steel-making furnace dust through composite calcification-chlorination of the waste incineration fly ash to obtain a valuable-metal-enriched volatile phase, and step-by-step deposition separation is carried out.

Description

Technical Field

[0001] The invention relates to the technical field of harmless disposal of hazardous waste and comprehensive utilization of resources, and specifically to a method for calcifying and chlorinating waste incineration fly ash to compositely activate inert zinc ferrite in steelmaking furnace dust and volatilize and enrich zinc, lead, potassium and sodium. Background Art

[0002] With my country's rapid industrialization, crude steel production reached 1.019 billion tons in 2023, accounting for 54.2% of global crude steel production. With the continued expansion of steel applications and the implementation of the dual-carbon policy, the reuse of scrap steel after its service life will be a smelting trend now and in the future. Currently, due to the large-scale use of zinc for steel corrosion protection, galvanized scrap steel produced after smelting in electric arc furnaces or converters produces a large amount of zinc-containing steelmaking dust. my country produces approximately 10 million tons of converter dust and 1.5 million tons of electric furnace dust annually. Due to its high heavy metal zinc content, it is classified as hazardous waste and urgently needs to be properly disposed of. Furthermore, because zinc and iron form stable compounds, neither can be recycled, resulting in a waste of resources.

[0003] Also classified as hazardous solid waste is waste incineration fly ash, whose generation has been steadily increasing in recent years. With the development of industrialization and urbanization, the amount of municipal waste generated has been increasing year by year. According to statistics, my country produces 10 million tons of waste incineration fly ash annually. Its disposal methods mainly include landfill and incineration. In recent years, due to the use of waste incineration for power generation, the incineration of municipal waste has increased to over 80% of the total. This has led to the massive generation of waste incineration fly ash, which contains various heavy metals (such as lead, cadmium, and zinc) and dioxins, known as the "poison of the century." These ash poses a significant threat to the environment and urgently needs to be disposed of.

[0004] Currently, the main methods for treating zinc-containing steelmaking dust are carbon thermal reduction in pyrometallurgy and strong acid leaching in hydrometallurgy. The carbon thermal reduction method mainly reduces zinc oxide or zinc ferrite by adding a reducing agent, carbon, so that the reduced product zinc volatilizes under high temperature conditions, thereby achieving the purpose of separation. Although this method is simple and efficient, it will produce greenhouse gas CO2, which is not conducive to environmental sustainability. For strong acid leaching, it adds an acidic solution to leach the target element, followed by neutralization, replacement, and electrolytic deposition. Although this method reduces carbon emissions, the process is lengthy and requires the use of large amounts of acid and alkali reagents. Improper handling will cause great harm to the environment.

[0005] For waste incineration fly ash, which contains a large amount of calcium-containing inorganics and chlorine-containing organics, this invention, based on the calcification and chlorination during the pyrometallurgical treatment of zinc-containing steelmaking dust, can take advantage of the complementarity of the two hazardous solid waste resources for comprehensive hazardous waste disposal. The present invention can comprehensively utilize waste incineration fly ash and zinc-containing steelmaking dust to perform a composite calcification-chlorination activation treatment to treat the inert component zinc ferrite in the steelmaking dust. This method synergistically treats the two hazardous wastes, achieving self-contained harmlessness and resource reuse. Summary of the Invention

[0006] To address these issues, the present invention provides a method for the combined activation of inert zinc ferrite in steelmaking dust through calcification and chlorination of waste incineration fly ash, and for the volatilization and enrichment of zinc, lead, potassium, and sodium. This method addresses the difficulties in recycling zinc-containing steelmaking dust and the growing difficulty in treating waste incineration fly ash. Drawing on existing calcification and chlorination treatment methods in pyrometallurgy, this method proposes a one-step, synergistic, combined calcification and chlorination method for the activation of inert zinc ferrite in zinc-containing steelmaking dust using calcium and chlorine in waste incineration fly ash.

[0007] The method for calcifying and chlorinating waste incineration fly ash to activate inert zinc ferrite in steelmaking furnace dust and volatilize and enrich zinc, lead, potassium and sodium comprises the following steps:

[0008] S100 raw material preparation: The raw materials are prepared according to the mineral composition of the waste incineration fly ash and steelmaking dust to obtain a uniform mixture; the particle size d50 of the steelmaking dust is ≤150μm to ensure effective mixing with the waste incineration fly ash particles;

[0009] S200 high temperature calcination: the obtained mixture is supplemented with an inert gas flow and sent to a high temperature zone for calcination; the inert gas flow is nitrogen or argon, and the gas flow speed is controlled at 0.5-1.0 m / s. The inert gas flow is preferably argon to more effectively inhibit the secondary oxidation of the metal oxide;

[0010] S300 desublimation enrichment: After calcification-chlorination composite activation and high-temperature roasting, an activated zinc-lead-potassium-sodium rich phase is produced, which is carried by the air flow into the low-temperature zone for desublimation enrichment;

[0011] S400 step-by-step deposition: The obtained enriched phase is subjected to step-by-step deposition and enrichment to obtain zinc, lead, potassium and sodium enriched products.

[0012] The above-mentioned method provided by the present invention first mixes and granulates the waste incineration fly ash with steelmaking dust, wherein the steelmaking dust includes converter ash and electric arc furnace ash. The waste incineration fly ash mainly serves as a calcium source and a chlorine source, which can effectively composite and activate the inert phase zinc ferrite to produce a volatile phase zinc oxide, efficiently recover heavy metal zinc, and the remaining iron oxides can be returned to the ironmaking process. The present invention uses waste incineration fly ash and zinc-containing steelmaking dust for composite reuse, making hazardous waste harmless and resource-based; in addition, the present invention also allows the valuable elements potassium and sodium in the waste incineration fly ash to be recycled, avoiding the waste of non-ferrous metal resources and improving the economic benefits of the process.

[0013] Optionally, step S100 is specifically as follows: (1) mixing waste incineration fly ash and steelmaking furnace dust uniformly at a ratio of 2-6:1; and (2) granulating the uniform mixture into particles with a radius of about 100 μm.

[0014] Optionally, the steelmaking dust in step (1) is a dust material obtained by mixing converter ash and electric arc furnace ash in a certain proportion.

[0015] Optionally, the granulation in step (2) can be performed using a disc granulator, with water added as a binder; the mass ratio of deionized water to the dust mixture is 1:10-12.

[0016] Preferably, the particle diameter in step (2) should be less than 200 μm and the proportion of particles with a particle size in the range of 50-150 μm should be greater than 80%. Since the reaction is a solid-solid reaction, in order to improve its reaction efficiency, it needs to be granulated in advance.

[0017] Optionally, the granulator described in step (2) can be a disc granulator. When the disc diameter is 80 cm, the disc inclination angle can be selected from 45 to 60 degrees, and the rotation speed can be selected from 10 to 30 r / min.

[0018] Optionally, step S200 is specifically as follows: (3) before the mixture is sent into the high temperature zone, the temperature of the high temperature zone needs to be controlled to 1000-1250°C; (4) a plasma torch array is set in the high temperature zone, including a DC arc plasma torch (power 8-10kW, working gas is argon) and a radio frequency induction plasma torch (power 10-15kW, working gas is argon hydrogen mixed gas, hydrogen accounts for 10-20vol%), and the two plasma torches work alternately, with a working cycle of 10-12 minutes / time; at the same time, a mechanical vibration treatment is set in the roasting equipment, the vibration frequency is 40-50 times / minute, the vibration force is 8-12N, and finally ZnCl2, PbCl2, KCl, and NaCl volatile phases are generated; (5) the generated volatile phase will be carried by the inert gas flow to the low temperature zone for condensation and enrichment. The DC arc plasma torch produces a high-energy-density plasma jet (temperature can reach 5000-10000K), which is used to quickly heat the material and initiate the initial reaction; the radio frequency induction plasma torch provides gentle and continuous energy input to maintain the active atmosphere in the reaction area (such as hydrogen free radicals and chlorine free radicals). The two plasma torches work alternately to form periodic energy pulses, promote the cyclic heating and cooling of the material particles, generate thermal stress to break the particles, and increase the reaction specific surface area. Its working principle is to use the complementary characteristics of different plasma modes to solve the problems of uneven energy distribution of a single plasma source and sintering caused by local overheating, and to achieve efficient and uniform reaction excitation; the mechanical vibration device can effectively prevent the material from sticking and accumulating on the inner wall and components of the roasting equipment through periodic vibration, ensure that the material is evenly heated and fully reacts, and avoid inadequate reaction and equipment blockage caused by material agglomeration or adhesion.

[0019] Alternatively, the selected heating device only needs to contain a heating portion and a ventilation or cooling portion.

[0020] Preferably, the high temperature zone preheating in step (3) is specifically to heat the high temperature zone to 1000-1100° C. in advance and then place the sample to reduce the generation of side reactions during the heating process.

[0021] Preferably, the inert atmosphere in steps (4) and (5) can effectively inhibit the dense phase generated by the waste incineration fly ash under high temperature roasting by promoting the decomposition of CaSO4: 10 The generation of (SiO4)3(SO4)3Cl2 effectively promotes the separation of the volatile phase and the forward progress of the reaction.

[0022] Optionally, step S400 is specifically as follows: (7) dissolving the obtained chloride-enriched phase in water; (8) controlling the pH of the solution to perform step-by-step precipitation, and controlling the pH to about 10 to precipitate Zn and Pb in the form of hydroxides; adjusting with NaOH or KOH; (9) dissolving the obtained hydroxide precipitate with sulfuric acid, wherein Pb will form a precipitate and continue to be preserved in the solid phase, and a zinc sulfate solution can be obtained, controlling the sulfuric acid concentration to 1-2 mol / L and the reaction temperature to 60-70°C, so that zinc hydroxide is dissolved and lead hydroxide is converted into lead sulfate precipitate; (10) the remaining NaCl and KCl can be separated by an industrial multi-effect evaporation crystallization process.

[0023] Optionally, the partial deposition method in step (8) may adopt carbonation precipitation to deposit Zn and Pb in the form of carbonates.

[0024] Preferably, NaOH is used to precipitate Zn and Pb in step (8), which can obtain Zn and Pb hydroxide precipitates with better separation effect.

[0025] Preferably, the crystallization method in step (8) is high-temperature evaporation crystallization. Since the potassium and sodium salts in the volatile matter mainly exist in the form of chloride salts, and the solubility of chloride salts does not change significantly with temperature, the production efficiency of high-temperature evaporation crystallization is higher than that of cooling crystallization.

[0026] Beneficial effects:

[0027] This invention innovatively combines waste incineration fly ash with zinc-containing steelmaking dust, utilizing the calcium and chlorine sources in the fly ash as natural composite activators. This process, without the need for additional chemical reagents, decomposes the inert zinc ferrite structure in the steelmaking dust through a dual calcification-chlorination process, converting it into volatile chlorides such as ZnCl2 and PbCl2 while simultaneously releasing iron oxides. This process not only avoids the drawbacks of traditional pyrometallurgical processes requiring the addition of carbon reducing agents or the large amounts of acid and alkali required by wet processes, but also significantly improves activation efficiency through optimized mass transfer through solid-solid reactions (particle size ≤ 200μm). The resulting iron-containing tailings can be directly reused in the ironmaking process, achieving a closed-loop "hazardous waste-to-raw material" cycle.

[0028] Through the synergistic effect of temperature control and inert gas flow, valuable elements such as Zn, Pb, K, and Na are volatilized and enriched in the form of chlorides (volatility rate > 95%), and directional separation is achieved through a step-by-step deposition process:

[0029] Zinc and lead separation: Adjust pH to 10 to make Zn 2+ , Pb 2+ The zinc and lead are separated efficiently by hydroxide precipitation and sulfuric acid dissolution, with a Zn recovery rate of 92%-94% and a Pb recovery rate of 90%-92%. The zinc sulfate solution can be directly used for electrolytic zinc extraction, and the lead sulfate solid phase can be further used to recover lead metal.

[0030] Potassium and sodium separation: Multi-effect high-temperature evaporation crystallization is adopted, and the solubility characteristics of chloride salts are utilized to achieve step-by-step crystallization of NaCl and KCl. The total recovery rate is greater than 91%, and the obtained crystals can be used as industrial-grade salt raw materials.

[0031] Compared with the traditional single treatment process, the comprehensive metal recovery rate of the present invention is significantly improved, which significantly improves the economic benefits of hazardous waste resource utilization.

[0032] Figures in the specification

[0033] Figure 1 This is the XRD pattern of valuable element enriched ash. DETAILED DESCRIPTION

[0034] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] The present invention provides a method for calcifying and chlorinating waste incineration fly ash to activate inert zinc ferrite in steelmaking furnace dust and volatilize and enrich zinc, lead, potassium and sodium, comprising the following steps:

[0036] Raw material combination: Based on the mineral phase composition of waste incineration fly ash and steelmaking dust, the waste incineration fly ash: steelmaking dust is uniformly mixed in a mass ratio of 2-6:1, deionized water is added as a binder (the mass ratio of deionized water to the mixture is 1:10-12), and microparticles with a particle size of ≤200 μm are formed in a disc granulator to form a uniform mixture. The steelmaking dust includes metallurgical hazardous waste such as converter ash and electric arc furnace ash containing zinc ferrite, zinc oxide, lead oxide and alkali metal oxides, and has a particle size d50 ≤150 μm. The mass ratio is such that the waste incineration fly ash is in excess relative to the steelmaking dust to provide the calcium source (CaO from the fly ash) and chlorine source (CaClOH from the fly ash) required for calcification-chlorination composite activation. The micronization treatment improves solid-solid reaction mass transfer by reducing the particle size to ≤200 μm.

[0037] High temperature calcination: The homogeneous mixture is sent into a high temperature zone controlled at 1000-1250°C in an inert gas flow environment for calcination. The inert gas flow is nitrogen or argon, and the gas flow speed is controlled at 0.5-1.0m / s. The inert atmosphere promotes the decomposition of CaSO4 and inhibits the formation of dense phase Ca 10(SiO4)3(SO4)3Cl2 is generated, and a plasma torch array is set in the high temperature zone, including a DC arc plasma torch (power 8-10kW, working gas is argon) and a radio frequency induction plasma torch (power 10-15kW, working gas is argon-hydrogen mixed gas, hydrogen accounts for 10-20vol%), and the two plasma torches work alternately, with a working cycle of 10-12 minutes / time; at the same time, a mechanical vibration treatment is set in the roasting equipment, the vibration frequency is 40-50 times / minute, and the vibration force is 8-12N, and finally ZnCl2, PbCl2, KCl, and NaCl volatile phases are generated; the oxygen content of the inert gas flow environment is ≤0.5%, and the secondary oxidation of metal oxides is suppressed by maintaining a low oxygen atmosphere, preferably argon, so as to more effectively suppress the secondary oxidation of metal oxides.

[0038] Condensation and enrichment: The volatile phase is carried by an inert gas flow into a low-temperature zone (controlled at 300-500°C). The volatile phase is condensed in different areas of the furnace wall by gradient cooling, and condenses when encountering cold at the furnace wall to form chloride salt enrichment.

[0039] Stepwise deposition: After dissolving the chloride salt enrichment in water, NaOH or KOH is used to adjust the pH value of the solution to 10, and no impurity ions are introduced during the adjustment process, so that Zn and Pb are precipitated in the form of hydroxides; the obtained hydroxide precipitate is acid-dissolved with sulfuric acid (sulfuric acid concentration is 1-2 mol / L, reaction temperature is 60-70°C), so that zinc hydroxide is dissolved and lead hydroxide is converted into lead sulfate precipitate, and zinc sulfate solution and lead-containing solid phase are separated; the remaining NaCl and KCl mixed solution is separated by a multi-effect evaporation crystallization process (evaporation temperature is controlled at 100-120°C), and NaCl and KCl are crystallized step by step through the salting-out effect to obtain zinc, lead and potassium and sodium enriched products.

[0040] The treatment method provided by the present invention achieves the harmlessness and resource utilization of hazardous waste through the synergistic composite activation of waste incineration fly ash and steelmaking furnace dust, and efficiently recovers valuable metals such as zinc, lead, potassium, and sodium, with significant environmental benefits.

[0041] The following are specific embodiments:

[0042] Example 1

[0043] Raw material combination

[0044] Waste incineration fly ash: steelmaking dust (converter ash, d50 = 120 μm) = 2:1 (mass ratio);

[0045] Deionized water was added (mixture:deionized water=10:1, mass ratio), and microparticles with a particle size of ≤200 μm (50-150 μm particles accounted for 85%) were prepared in a disc granulator.

[0046] High temperature roasting

[0047] High temperature zone temperature: 1000℃;

[0048] Calcination: A plasma torch array is set up in the high-temperature zone, including a DC arc plasma torch (power 8kW, working gas is argon) and a radio frequency induction plasma torch (power 10kW, working gas is an argon-hydrogen mixture gas, hydrogen accounts for 10 vol%). The two plasma torches work alternately with a working cycle of 10 minutes / time; at the same time, a mechanical vibration treatment is set in the roasting equipment, with a vibration frequency of 40 times / minute and a vibration force of 8N, and finally ZnCl2, PbCl2, KCl, and NaCl volatile phases are generated;

[0049] Inert gas flow: nitrogen, flow rate 0.5m / s, oxygen content ≤0.5%;

[0050] Calcination time: 2h;

[0051] Condensation and enrichment

[0052] Low temperature zone temperature: 300-400℃, gradient cooling and segmented desublimation;

[0053] step-by-step deposition

[0054] pH adjustment: adjust the NaOH solution to pH = 10, and filter to obtain Zn(OH)2 and Pb(OH)2 precipitates;

[0055] Sulfuric acid dissolution: Sulfuric acid concentration 1 mol / L, temperature 60°C, separation to obtain zinc sulfate solution and lead sulfate solid phase;

[0056] Evaporation crystallization: Multi-effect evaporation temperature is 100℃ to obtain NaCl and KCl crystals.

[0057] Example 2

[0058] Raw material combination

[0059] Waste incineration fly ash: steelmaking dust (arc furnace dust, d50 = 150 μm) = 3:1 (mass ratio);

[0060] Deionized water was added (mixture:deionized water=12:1, mass ratio), and granulation was performed to a particle size of ≤200 μm (50-150 μm particles accounted for 82%).

[0061] High temperature roasting

[0062] High temperature zone temperature: 1100℃;

[0063] Calcination: A plasma torch array is set up in the high-temperature zone, including a DC arc plasma torch (power 9kW, working gas is argon) and a radio frequency induction plasma torch (power 12kW, working gas is an argon-hydrogen mixture gas, hydrogen accounts for 16vol%). The two plasma torches work alternately with a working cycle of 10-12 minutes per time; at the same time, a mechanical vibration treatment is set in the roasting equipment, with a vibration frequency of 45 times / minute and a vibration force of 10N, and finally ZnCl2, PbCl2, KCl, and NaCl volatile phases are generated;

[0064] Inert gas flow: argon, flow rate 1.0m / s, oxygen content ≤0.5%;

[0065] Firing time: 1.5h

[0066] Condensation and enrichment

[0067] Low temperature zone temperature: 400-500℃, gradient cooling and segmented desublimation;

[0068] step-by-step deposition

[0069] pH adjustment: KOH solution was adjusted to pH = 10, and Zn(OH)2 and Pb(OH)2 precipitates were obtained by filtration;

[0070] Sulfuric acid dissolution: Sulfuric acid concentration 2 mol / L, temperature 70°C, separation to obtain zinc sulfate solution and lead sulfate solid phase;

[0071] Evaporation crystallization: Multi-effect evaporation temperature is 120℃ to obtain NaCl and KCl crystals.

[0072] Example 3

[0073] Raw material combination

[0074] Waste incineration fly ash: steelmaking dust (converter ash + electric arc furnace ash, mass ratio 1:1, d50 = 130μm) = 6:1 (mass ratio);

[0075] Deionized water was added (mixture:deionized water=11:1, mass ratio), and granulation was performed to a particle size of ≤200 μm (50-150 μm particles accounted for 88%).

[0076] High temperature roasting

[0077] High temperature zone temperature: 1250℃;

[0078] Calcination: A plasma torch array is set up in the high-temperature zone, including a DC arc plasma torch (power 10kW, working gas is argon) and a radio frequency induction plasma torch (power 15kW, working gas is an argon-hydrogen mixture gas, hydrogen accounts for 20vol%). The two plasma torches work alternately with a working cycle of 12 minutes per time; at the same time, a mechanical vibration treatment is set in the roasting equipment, with a vibration frequency of 50 times / minute and a vibration force of 12N, and finally ZnCl2, PbCl2, KCl, and NaCl volatile phases are generated;

[0079] Inert gas flow: nitrogen, flow rate 0.8m / s, oxygen content ≤0.5%;

[0080] Calcination time: 2h;

[0081] Condensation and enrichment

[0082] Low temperature zone temperature: 350-450℃, gradient cooling and segmented desublimation;

[0083] step-by-step deposition

[0084] pH adjustment: adjust the NaOH solution to pH = 10, and filter to obtain Zn(OH)2 and Pb(OH)2 precipitates;

[0085] Sulfuric acid dissolution: Sulfuric acid concentration 1.5 mol / L, temperature 65°C, separation to obtain zinc sulfate solution and lead sulfate solid phase;

[0086] Evaporation crystallization: Multi-effect evaporation temperature is 110℃ to obtain NaCl and KCl crystals.

[0087] Control group 1: Steelmaking dust treated with carbothermal reduction alone (without waste incineration fly ash)

[0088] Process: Carbon powder and steelmaking dust are mixed in a ratio of 1:5, roasted at 1250℃ for 3h, and Zn is recovered by water leaching. 2+ .

[0089] Control group 2: The difference from Example 1 is that the plasma torch array is not provided in the high temperature zone.

[0090] The metal recovery rate of the embodiment and the control group method was tested:

[0091] Detection method

[0092] Zinc and lead content: atomic absorption spectrometry (AAS)

[0093] Potassium and sodium content: flame photometry

[0094] Test results:

[0095] Table 1

[0096]

[0097]

[0098] As can be seen from Table 1, the method of the present invention has a high recovery rate for Zn, Pb, K and Na.

[0099] according to Figure 1 It can be seen that after the composite calcification-chlorination activation of waste incineration fly ash, zinc ferrite in zinc-containing steelmaking dust is decomposed to form volatile matter Zn, K, Na, etc., effectively achieving the purpose of harmless treatment of hazardous waste and resource utilization of valuable metals.

[0100] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. The preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification.

Claims

1. A method for calcifying and chlorinating waste incineration fly ash to activate inert zinc ferrite in steelmaking dust and volatilize and enrich zinc, lead, potassium and sodium, characterized in that: The following steps are involved: Raw material composition: Based on the mineral composition of waste incineration fly ash and steelmaking dust, mix them evenly at a mass ratio of waste incineration fly ash: steelmaking dust = 2-6:1, add deionized water as a binder, and use a disc granulator to produce particles with a particle size of ≤200μm to form a uniform mixture; the mass ratio of deionized water to the mixture is 1:10-12; High-temperature roasting: the homogeneous mixture is sent into a high-temperature zone controlled at a temperature of 1000-1250°C in an inert gas flow environment for roasting, and a plasma torch array is set in the high-temperature zone, including a DC arc plasma torch (power 8-10kW, working gas is argon) and a radio frequency induction plasma torch (power 10-15kW, working gas is argon-hydrogen mixed gas, hydrogen accounts for 10-20vol%), and the two plasma torches work alternately with a working cycle of 10-12 minutes / time; at the same time, a mechanical vibration treatment is set in the roasting equipment, the vibration frequency is 40-50 times / minute, and the vibration force is 8-12N, and finally ZnCl2, PbCl2, KCl, and NaCl volatile phases are generated; Condensation and enrichment: The volatile phase is carried by the inert gas flow into the low temperature zone, and sublimates when encountering cold at the furnace wall to form chloride salt enrichment; Stepwise deposition: After dissolving the chloride salt enrichment in water, the pH of the solution is adjusted to 10 to precipitate Zn and Pb in the form of hydroxides. The precipitate is separated by sulfuric acid dissolution to obtain a zinc sulfate solution and a lead-containing solid phase. The remaining NaCl and KCl mixed solution is separated by a multi-effect evaporation crystallization process to obtain zinc, lead and potassium and sodium enriched products.

2. The method according to claim 1, wherein: In the raw material matching step, the mass ratio makes the waste incineration fly ash excessive relative to the steelmaking dust to provide the calcium source and chlorine source required for the calcification-chlorination composite activation, and the micronization treatment improves the solid-solid reaction mass transfer by reducing the particle size to ≤200μm.

3. The method according to claim 2, wherein: The chlorine source required for the calcification-chlorination composite activation includes CaClOH in waste incineration fly ash.

4. The method according to claim 1, wherein: In the high temperature calcination step, the inert gas flow is nitrogen or argon, and the gas flow speed is controlled to be 0.5-1.0 m / s. The inert atmosphere promotes the decomposition of CaSO4 and inhibits the formation of dense phase Ca 10 (SiO4)3(SO4)3Cl2 is produced.

5. The method according to claim 4, characterized in that: The inert gas flow environment is preferably argon, and the argon atmosphere suppresses the secondary oxidation of metal oxides.

6. The method according to claim 1, wherein: In the desublimation and enrichment step, the temperature of the low temperature zone is controlled at 300-500° C., and the volatile phase is desublimated in different areas of the furnace wall in sections by gradient cooling.

7. The method according to claim 1, wherein: In the stepwise deposition step, NaOH or KOH is used to adjust the pH value of the solution to 10, and no impurity ions are introduced during the regulation process.

8. The method according to claim 1, wherein: During the sulfuric acid dissolution process, the sulfuric acid concentration is controlled to be 1-2 mol / L and the reaction temperature is 60-70° C., so that the zinc hydroxide is dissolved and the lead hydroxide is converted into lead sulfate precipitation.

9. The method according to claim 1, wherein: The evaporation temperature of the multi-effect evaporation crystallization process is controlled at 100-120° C., and the fractional crystallization of NaCl and KCl is achieved through the salting-out effect.

10. The method according to claim 1, wherein: The steelmaking dust includes metallurgical hazardous wastes such as converter ash and electric arc furnace ash containing zinc ferrite, zinc oxide, lead oxide and alkali metal oxides, and its particle size d50 is ≤150μm.

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