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

Abstract

The present application relates to the field of hazardous waste harmless disposal and resource comprehensive utilization, and particularly relates to a method for calcification-chlorination composite activation of inert zinc ferrite in garbage incineration fly ash and steel furnace dust, and volatilization and enrichment of zinc, lead, potassium and sodium, comprising the following steps: S100: raw material compatibility is performed according to the mineral phase composition of garbage incineration fly ash and steel furnace dust to obtain a mixture; S200: the obtained mixture is sent into a high-temperature zone for roasting with the aid of an inert gas flow; S300: after calcification-chlorination composite activation high-temperature roasting, an activated zinc, lead, potassium and sodium-rich phase is generated and is brought into a low-temperature zone by the gas flow to condense and enrich; S400: the obtained enriched phase is subjected to step-by-step deposition and enrichment to obtain zinc, lead and potassium and sodium enrichment products. The method is aimed at the problem that zinc-containing steel furnace dust is difficult to utilize and the problem that the amount of garbage incineration fly ash is increasing year by year, and proposes to utilize garbage incineration fly ash to composite calcification-chlorination activation of inert zinc ferrite in zinc-containing steel furnace dust to obtain a valuable metal enrichment volatilization phase, and to perform step-by-step deposition and separation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hazardous waste harmless disposal and resource comprehensive utilization, in particular to a method for calcification-chlorination composite activation of inert zinc ferrite in waste incineration fly ash and volatilization and enrichment of zinc, lead, potassium and sodium. BACKGROUND

[0002] With the rapid development of industrialization in China, the crude steel output in China in 2023 is 10.19 million tons, accounting for 54.2% of the global crude steel output. With the continuous expansion of the application field of steel materials and the implementation of the double carbon policy, the recycling of waste steel after the service period will be the smelting trend today and in the future. Nowadays, due to the large-scale use of zinc for steel corrosion protection, a large amount of zinc-containing steelmaking dust will be produced after the galvanized waste steel undergoes electric arc furnace smelting or converter smelting. China produces about 10 million tons of converter dust and 1.5 million tons of electric furnace dust per year. Due to its high zinc content, it is classified as hazardous waste and needs to be properly disposed of. And because of the stable compound of zinc and iron, both of them cannot be recycled, causing resource waste.

[0003] Also belonging to hazardous solid waste is the waste incineration fly ash whose generation has been increasing in recent years. With the development of industrialization and urbanization, the amount of urban waste produced is increasing year by year. According to statistics, China produces 10 million tons of waste incineration fly ash per year. The main disposal methods are landfill and incineration. In recent years, due to the use of waste incineration for power generation, the method of incinerating municipal waste has grown to more than 80% of the total. This has led to the large-scale production of waste incineration fly ash, and the various heavy metals (such as lead, cadmium, zinc) and dioxins, known as "the century's poison", have caused great harm to the environment and need to be disposed of.

[0004] The main disposal methods for zinc-containing steelmaking dust today are the carbon thermal reduction method in pyrometallurgy and the strong acid leaching method in hydrometallurgy. The carbon thermal reduction method mainly adds a reducing agent, carbon, to reduce zinc oxide or zinc ferrite, so that the reduced product zinc can be volatilized under high temperature conditions to achieve separation. Although this method is simple and efficient, it will produce greenhouse gas CO2, which is not conducive to environmental sustainable development. For strong acid leaching, the target element is leached by adding an acidic solution, followed by neutralization, displacement and electrolytic deposition. Although this method reduces carbon emissions, the process is long and requires the use of a large amount of acid and base reagents, which can cause great harm to the environment if not properly handled.

[0005] For the fly ash of waste incineration, which contains a large amount of calcium-containing inorganic substances and chlorine-containing organic substances, the present application is based on the calcification and chlorination in the pyroprocessing of zinc-containing steelmaking dust, and can utilize the complementarity of the two hazardous solid waste resources for comprehensive disposal of hazardous waste. The present application can comprehensively utilize the fly ash of waste incineration and zinc-containing steelmaking dust to perform complex calcification-chlorination activation treatment on the inert ingredient zinc ferrite in the steelmaking dust. This method cooperatively processes the two hazardous wastes, and realizes self-carrying harmless treatment of hazardous waste and resource recycling. SUMMARY

[0006] In view of the above problems, the present application provides a method for calcification-chlorination complex activation of inert zinc ferrite in steelmaking dust and volatilization and enrichment of zinc, lead, potassium and sodium from fly ash of waste incineration. The method is aimed at the problem that zinc-containing steelmaking dust is difficult to recycle, and the problem that fly ash of waste incineration is difficult to dispose year by year. By associating with the existing calcification and chlorination treatment methods in pyroprocessing, the method is proposed to utilize calcium and chlorine in fly ash of waste incineration to perform one-step synergistic complex calcification-chlorination activation on inert phase zinc ferrite in zinc-containing steelmaking dust.

[0007] The method for calcification-chlorination complex activation of inert zinc ferrite in steelmaking dust and volatilization and enrichment of zinc, lead, potassium and sodium from fly ash of waste incineration comprises the following steps:

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

[0009] S200 High-temperature roasting: The obtained mixture is sent into a high-temperature zone for roasting with the aid of an inert gas stream; the inert gas stream is nitrogen or argon, and the gas stream speed is controlled to be 0.5-1.0 m / s; the inert gas stream is preferably argon to more effectively inhibit the secondary oxidation of metal oxides;

[0010] S300 Condensation enrichment: After the calcification-chlorination complex activation high-temperature roasting, activated zinc, lead, potassium and sodium phases are produced and are brought into a low-temperature zone by the gas stream for condensation enrichment;

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

[0012] The method provided by the application comprises the following steps: firstly, mixing and granulating waste incineration fly ash and steelmaking furnace dust, wherein the steelmaking furnace dust comprises converter dust and electric arc furnace dust; the waste incineration fly ash mainly serves as a calcium source and a chlorine source, can effectively activate inert zinc ferrite, make the zinc ferrite generate volatile zinc oxide, and recycle the zinc in a high efficiency; and the residual iron oxide can be recycled to the iron smelting process. The waste incineration fly ash and the zinc-containing steelmaking furnace dust are recycled in combination, so that the hazardous waste is harmless and recycled; in addition, the valuable potassium and sodium elements in the waste incineration fly ash can be recycled, the waste of non-ferrous metal resources is avoided, and the economic benefit of the process is improved.

[0013] Optionally, the step S100 specifically comprises the following steps: (1) mixing the waste incineration fly ash and the steelmaking furnace dust in a ratio of 2-6:1; and (2) granulating the mixture into particles with a radius of about 100 microns.

[0014] Optionally, the steelmaking furnace dust in the step (1) is converter dust and electric arc furnace dust, and the dust materials are mixed in a certain ratio.

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

[0016] Preferably, the particle diameter in the step (2) is less than 200 microns, and the proportion of particles with a particle size in the range of 50-150 microns is greater than 80%. Since the reaction is a solid-solid reaction, the granulation treatment is required in advance to improve the reaction efficiency.

[0017] Optionally, the granulator in the step (2) can be a disc granulator, when the disc diameter is 80 cm, the disc inclination angle is selected from 45-60°, and the rotating speed is selected from 10-30 r / min.

[0018] Optionally, step S200 is specifically: (3) the temperature of the high-temperature zone is controlled to 1000-1250℃ before the mixture is sent into the high-temperature zone; (4) a plasma torch array is arranged in the high-temperature zone, including a direct current 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%), the two plasma torches work alternately, and the working cycle is 10-12 minutes / time; at the same time, a mechanical vibration treatment is arranged in the calcination equipment, the vibration frequency is 40-50 times / minute, and the vibration force is 8-12N, finally generating ZnCl2, PbCl2, KCl and NaCl volatile phases; (5) the generated volatile phases are carried to the low-temperature zone by the inert gas flow and sublimate and enrich. The direct current arc plasma torch generates a high-energy density plasma jet (temperature up to 5000-10000K) for rapidly heating the materials and initiating the initial reaction; the radio frequency induction plasma torch provides a mild and continuous energy input to maintain the active atmosphere (such as hydrogen radicals and chlorine radicals) of the reaction area. The two plasma torches work alternately to form a periodic energy pulse, promote the cyclic heating and cooling of the material particles, produce thermal stress to break the particles, and increase the reaction specific surface area. The principle is to use the complementary characteristics of different plasma modes to solve the problem of uneven energy distribution and local overheating caused by sintering of a single plasma source, and realize efficient and uniform reaction excitation; the mechanical vibration device can effectively prevent the materials from sticking and accumulating on the inner wall and parts of the calcination equipment through periodic vibration, ensure uniform heating and sufficient reaction of the materials, and avoid the problems of insufficient reaction and equipment blockage caused by material agglomeration or adhesion

[0019] Optionally, the selected heating equipment only needs to contain a heating part and a ventilation or cooling part.

[0020] Preferably, the preheating of the high-temperature zone in step (3) is specifically that the high-temperature zone is heated to 1000-1100℃ in advance, and then the sample is put in to reduce the generation of side reactions in the heating process.

[0021] Preferably, the inert atmosphere in steps (4) and (5) can promote the decomposition of CaSO4, thereby effectively inhibiting the generation of dense phases: Ca 10 (SiO4)3(SO4)3Cl2, thereby effectively promoting the separation of the volatile phase and the forward progress of the reaction.

[0022] Optionally, step S400 is specifically: (7) dissolving the obtained chloride-rich phase in water; (8) controlling the pH of the solution to carry out step-by-step deposition, and the Zn and Pb can be deposited in the form of hydroxides by controlling the pH to about 10; NaOH or KOH is used for adjustment; (9) using sulfuric acid to acid-dissolve the obtained hydroxide precipitate, wherein the Pb will form a precipitate and be kept in the solid phase, and a zinc sulfate solution can be obtained, the concentration of sulfuric acid is controlled to be 1-2 mol / L, and the reaction temperature is controlled to be 60-70 DEG C, so that the zinc hydroxide is dissolved and the lead hydroxide is converted into lead sulfate precipitate; (10) the remaining NaCl and KCl can be separated by using a multi-effect evaporation crystallization process for industrial application.

[0023] Optionally, the step-by-step deposition method in step (8) can use carbonation deposition to deposit the Zn and Pb in the form of carbonates.

[0024] Preferably, the NaOH is used to precipitate the Zn and Pb in step (8), and the Zn and Pb hydroxide precipitates obtained have better separation effect.

[0025] Preferably, the crystallization mode in step (8) is high-temperature evaporation crystallization. Since the potassium and sodium salts in the volatile components mainly exist in the form of chlorides, and the solubility of chlorides does not change obviously with temperature, the production efficiency of high-temperature evaporation crystallization is higher than that of temperature reduction crystallization.

[0026] Beneficial effects:

[0027] The application breaks through the coordination of waste incineration fly ash and zinc-containing steelmaking furnace dust, uses calcium source and chlorine source in fly ash as a natural composite activator, without additional chemical reagents, decomposes the inert zinc ferrite structure in the steelmaking furnace dust through the double effects of calcification-chlorination, converts it into volatile chlorides such as ZnCl2 and PbCl2, and releases iron oxides. This process not only avoids the drawbacks of traditional fire method needing external carbon reducing agent or wet method needing a large amount of acid and alkali, but also optimizes the mass transfer (particle size ≤200 μm) through solid-solid reaction, so that the activation efficiency is obviously improved, and the finally formed iron-containing tailings can be directly used for ironmaking process, realizing the closed loop circulation of "hazardous waste-raw material".

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

[0029] Zinc-lead separation: adjusting the pH to 10 to make Zn 2+ , Pb 2+ hydroxide precipitate, and then realizing high-efficiency separation of zinc and lead by sulfuric acid acid-dissolution, the recovery rate of Zn is 92%-94%, the recovery rate of Pb is 90%-92%, the zinc sulfate solution can be directly used for electrolytic zinc extraction, and the lead sulfate solid phase can be further used for lead metal recovery;

[0030] Potassium-sodium separation: multi-effect high-temperature evaporation crystallization is adopted, NaCl and KCl are step-by-step crystallized by using the solubility characteristics of chloride salt, and the total recovery rate is >91%, and the obtained crystals can be used as industrial-grade salt raw materials.

[0031] Compared with the traditional single treatment process, the metal comprehensive recovery rate of the application is obviously improved, and the economic benefit of hazardous waste resource utilization is significantly improved.

[0032] Drawings of the specification

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

[0034] The technical solutions in the embodiments of the application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0035] The application provides a method for calcification-chlorination composite activation of inert zinc ferrite in waste incineration fly ash and volatilization and enrichment of zinc, lead, potassium and sodium in steelmaking furnace dust, comprising the following steps:

[0036] Raw material compatibility: according to the mineral phase composition of waste incineration fly ash and steelmaking furnace dust, the waste incineration fly ash and the steelmaking furnace dust are mixed uniformly at 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 prepared in a disc granulator to form a uniform mixture; the steelmaking furnace dust includes converter dust, electric arc furnace dust and other metallurgical hazardous wastes containing zinc ferrite, zinc oxide, lead oxide and alkali metal oxides, and the particle size d50 is ≤150 μm; the mass ratio makes the waste incineration fly ash excessive relative to the steelmaking furnace dust to provide the required calcium source (CaO from the fly ash) and chlorine source (CaClOH from the fly ash) for calcification-chlorination composite activation, and the microparticle treatment improves the solid-solid reaction mass transfer by reducing the particle size to ≤200 μm.

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

[0038] Desublimation enrichment: the volatile phase is carried into a low temperature zone (temperature control is 300-500 DEG C) by an inert gas flow, and the volatile phase is desublimated in different regions of the furnace wall in stages by gradient cooling, and the desublimation at the furnace wall forms a chlorides enrichment.

[0039] Step-by-step deposition: after the chlorides enrichment is dissolved in water, the pH value of the solution is adjusted to 10 by using NaOH or KOH, no impurity ions are introduced in the adjustment process, and Zn and Pb are precipitated in the form of hydroxides; the obtained hydroxide precipitate is acid-dissolved by using sulfuric acid (sulfuric acid concentration is 1-2 mol / L, and reaction temperature is 60-70 DEG C), so that the zinc hydroxide is dissolved and the lead hydroxide is converted into lead sulfate precipitate, and zinc sulfate solution and a lead-containing solid phase are separated; the remaining NaCl and KCl mixed solution is separated by using a multi-effect evaporation crystallization process (evaporation temperature control is 100-120 DEG C), and step-by-step crystallization of NaCl and KCl is realized through salting-out effect, so that zinc, lead and potassium-sodium enrichment products are obtained.

[0040] The treatment method provided by the application realizes harmless treatment and resource utilization of hazardous waste by synergistic and composite activation of waste incineration fly ash and steelmaking furnace dust, and efficiently recovers valuable metals such as zinc, lead, potassium and sodium, and has remarkable environmental protection benefits.

[0041] The following is a specific embodiment:

[0042] Embodiment 1

[0043] Raw material compatibility

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

[0045] Deionized water is added (mixture: deionized water = 10:1, mass ratio), and microparticles (50-150 μm particles account for 85 %) with a particle size of less than or equal to 200 μm are prepared in a disc granulator.

[0046] High-temperature calcination

[0047] High temperature zone temperature: 1000℃;

[0048] Roasting: Set up a plasma torch array in the high temperature zone, including a direct current arc plasma torch (power 8kW, working gas argon) and a radio frequency induction plasma torch (power 10kW, working gas argon-hydrogen mixed gas, hydrogen accounting for 10vol%), the two plasma torches work alternately, the working cycle is 10 minutes / time; At the same time, mechanical vibration treatment is set up in the roasting equipment, the vibration frequency is 40 times / minute, the vibration force is 8N, finally the volatile phase of ZnCl2, PbCl2, KCl, NaCl is generated;

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

[0050] Roasting time: 2h;

[0051] Condensation enrichment

[0052] Low temperature zone temperature: 300-400℃, gradient cooling sublimation;

[0053] Step-by-step deposition

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

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

[0056] Evaporation crystallization: multi-effect evaporation temperature 100℃, obtain NaCl and KCl crystals.

[0057] Example 2

[0058] Raw material compatibility

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

[0060] Add deionized water(mixture: deionized water = 12:1, mass ratio), granulate to particle size ≤200μm(50-150μm particles accounting for 82%).

[0061] High temperature roasting

[0062] High temperature zone temperature: 1100℃;

[0063] Roasting: Set up plasma torch array in high temperature zone, including direct current arc plasma torch (power 9 kW, working gas argon) and radio frequency induction plasma torch (power 12 kW, working gas argon-hydrogen mixture, hydrogen content 16 vol%), two plasma torches work alternately, working cycle 10-12 minutes / time; At the same time, set up mechanical vibration treatment in the roasting equipment, vibration frequency 45 times / min, vibration force 10 N, finally generate ZnCl2, PbCl2, KCl, NaCl volatile phase;

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

[0065] Roasting time: 1.5 h

[0066] Deposition of sublimation

[0067] Low temperature zone temperature: 400-500℃, gradient cooling sublimation;

[0068] Step-by-step deposition

[0069] pH adjustment: adjust to pH=10 with KOH solution, filter to obtain Zn(OH)2 and Pb(OH)2 precipitate;

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

[0071] Evaporation crystallization: multi-effect evaporation temperature 120℃, obtain NaCl and KCl crystals.

[0072] Example 3

[0073] Raw material compatibility

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

[0075] Add deionized water (mixture: deionized water = 11:1, mass ratio), granulate to particle size ≤200μm (50-150μm particles account for 88%).

[0076] High temperature roasting

[0077] High temperature zone temperature: 1250℃;

[0078] Roasting: In the high temperature zone, an array of plasma torches is set, including a direct current arc plasma torch (power 10 kW, working gas argon) and a radio frequency induction plasma torch (power 15 kW, working gas argon-hydrogen mixture, hydrogen content 20 vol%). The two plasma torches work alternately, with a working cycle of 12 minutes per time. At the same time, a mechanical shaking treatment is set in the roasting equipment, with a shaking frequency of 50 times per minute and a shaking force of 12 N. Finally, ZnCl2, PbCl2, KCl, and NaCl volatile phases are generated.

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

[0080] Roasting time: 2 h;

[0081] Deposition by sublimation

[0082] Low temperature zone temperature: 350-450℃, gradient cooling sublimation in sections;

[0083] Step-by-step deposition

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

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

[0086] Evaporation crystallization: multi-effect evaporation temperature 110℃, and obtain NaCl and KCl crystals.

[0087] Control group 1: only use carbon thermal reduction method to treat steelmaking furnace dust (without adding waste incineration fly ash)

[0088] Process: mix carbon powder with steelmaking furnace dust at a ratio of 1:5, roast at 1250℃ for 3 h, and recover Zn by water immersion 2+ .

[0089] Control group 2: the difference from Example 1 is that no plasma torch array is set in the high temperature zone.

[0090] Metal recovery rate detection of the example and control group methods:

[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 shown in Table 1, the method has high recovery rates of Zn, Pb, K and Na.

[0099] According to Figure 1 It can be seen that, after the composite calcification-chlorination activation of the waste incineration fly ash, the zinc ferrite in the zinc-containing steelmaking dust is broken down to form volatile Zn, K, Na and other components, thereby efficiently achieving the harmless treatment of hazardous waste and the resource utilization of valuable metal.

[0100] The above disclosed preferred embodiments of the present application are only used to help illustrate the present application. The preferred embodiments do not describe all the details and do not limit the present application to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of the present application.

Claims

1. A method for the calcification-chlorination composite activation of inert zinc ferrite in waste incineration fly ash and the volatilization enrichment of zinc, lead, potassium, and sodium in steelmaking furnace dust, characterized in that, Includes the following steps: Raw material compatibility: Based on the mineral phase composition of waste incineration fly ash and steelmaking furnace dust, the fly ash and steelmaking furnace dust are mixed evenly at a mass ratio of 2-6:

1. Deionized water is added as a binder, and the mixture is made into microparticles with a particle size ≤200μm in a disc granulator to form a homogeneous mixture. The mass ratio of deionized water to the mixture is 1:10-12. High-temperature calcination: The homogeneous mixture is fed into a high-temperature zone with a temperature controlled at 1000-1250℃ in an inert gas flow environment for calcination. A plasma torch array is set up in the high-temperature zone, including a DC arc plasma torch with a power of 8-10kW and argon as the working gas, and a radio frequency induction plasma torch with a power of 10-15kW and an argon-hydrogen mixture as the working gas with a hydrogen content of 10-20 vol%. The two plasma torches work alternately, with a working cycle of 10-12 minutes / cycle. At the same time, mechanical rapping is set up in the calcination equipment, with a rapping frequency of 40-50 times / minute and a rapping force of 8-12N. Finally, volatile phases of ZnCl2, PbCl2, KCl, and NaCl are generated. Sublimation enrichment: The volatile phase is carried into the low-temperature zone by the inert gas flow and condenses upon cooling 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 zinc sulfate solution and lead-containing solid phase. The remaining NaCl and KCl mixed solution is separated by multi-effect evaporation crystallization process to obtain zinc, lead and potassium sodium enriched products.

2. The method according to claim 1, characterized in that: In the raw material formulation step, the mass ratio makes the waste incineration fly ash in excess relative to the steelmaking furnace dust, so as to provide the calcium and chlorine sources required for calcification-chlorination composite activation. The micronization treatment improves solid-solid reaction mass transfer by reducing the particle size to ≤200μm.

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

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

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

6. The method according to claim 1, characterized in that: In the deposition and enrichment step, the temperature in the low-temperature zone is controlled at 300-500℃, and the volatile phase is deposited in different areas of the furnace wall in stages by gradient cooling.

7. The method according to claim 1, characterized in that: In the stepwise deposition process, the pH of the solution is adjusted to 10 using NaOH or KOH, and no impurity ions are introduced during the adjustment process.

8. The method according to claim 1, characterized in that: During the sulfuric acid dissolution process, the sulfuric acid concentration is controlled at 1-2 mol / L and the reaction temperature is 60-70℃, so that zinc hydroxide dissolves and lead hydroxide is converted into lead sulfate precipitate.

9. The method according to claim 1, characterized in that: The evaporation temperature of the multi-effect evaporation crystallization process is controlled at 100-120℃, and the stepwise crystallization of NaCl and KCl is achieved through the salting-out effect.

10. The method according to claim 1, characterized in that: The steelmaking furnace dust includes converter ash containing zinc ferrite, zinc oxide, lead oxide and alkali metal oxides, and electric arc furnace ash containing zinc ferrite, zinc oxide, lead oxide and alkali metal oxides, with a particle size d50≤150μm.

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