Comprehensive utilization method for dezincification rotary kiln to cooperatively process electric furnace fly ash

Abstract

The invention relates to a comprehensive utilization method for dezincification rotary kiln cooperative treatment of electric furnace fly ash. The comprehensive utilization method comprises the following steps that the electric furnace fly ash and blast furnace zinc-containing fly ash are sampled respectively; screening to remove large impurities larger than the aperture of a screen in the electric furnace fly ash, performing magnetic separation pretreatment on the blast furnace zinc-containing fly ash, and preliminarily separating part of ferromagnetic substances; then, the two kinds of dust are subjected to drying treatment; on the basis of a detection result in the step 2, weighing the electric furnace fly ash and the blast furnace zinc-containing fly ash according to a certain mass ratio, and then uniformly mixing the fly ash and the blast furnace zinc-containing fly ash; the evenly-mixed materials are fed into a dezincification rotary kiln through a constant feeder, the dezincification rotary kiln is at least divided into two sections with the temperature difference, the front section is a relative low-temperature area, the rear section is a relative high-temperature area, and the difference between the temperature of an outlet of the front section and the temperature of an inlet of the rear section is smaller than or equal to 50 DEG C; zinc-containing flue gas generated by calcination is collected and condensed, and then reacts with oxygen in the air to generate secondary zinc oxide. The method has the advantages of high zinc recovery rate and high purity of secondary zinc oxide.

Description

Technical Field

[0001] This invention relates to the field of co-recycling technology of electric furnace dust and dezincification rotary kiln, and more particularly to a comprehensive utilization method for co-processing electric furnace dust in a dezincification rotary kiln. Background Technology

[0002] Electric arc furnace (EAF) dust is the flue gas dust collected by the dust removal system during the EAF steelmaking process. One ton of EAF steel typically produces 10-20 kg of EAF dust. Its composition is complex and fluctuates greatly, with iron and zinc as the main valuable elements, while also containing harmful impurities including chloride ions, heavy metals, and alkali metals. It has extremely fine particle size, low carbon calorific value, is easily airborne, and has poor flowability, classifying it as HW23 hazardous waste in the National Hazardous Waste List. Heavy metals such as Zn, Pb, and Cd in EAF dust have high leaching toxicity. If open-air storage or simple landfill is used, heavy metals will seep into the soil and groundwater with rainwater, leading to excessive heavy metal levels in the soil and groundwater pollution, harming the ecosystem and human health. In traditional treatment processes (such as single rotary kilns and landfill), dioxins are easily generated under low-temperature conditions, far exceeding the limits of the National Standard for Pollution Control of Hazardous Waste Incineration, causing persistent organic pollution through atmospheric diffusion. If untreated electric arc furnace dust is directly returned to the sintering process, the chloride ions and alkali metals in it will accumulate in the blast furnace, causing blockages in the blast furnace flue gas system, corrosion of refractory materials, and shortening the blast furnace's lifespan. If low-calorific-value electric arc furnace dust is treated separately in a rotary kiln, additional fuel is required, significantly increasing the energy costs for steel companies. Furthermore, equipment blockages necessitate frequent kiln shutdowns for cleaning, reducing production efficiency.

[0003] Although it is hazardous waste, it contains high-value zinc and iron resources. The potential value of zinc in 1 ton of electric furnace dust is about 300-600 yuan, and iron can be used as a raw material for ironmaking, thus possessing the potential to transform hazardous waste into resources.

[0004] Existing publicly available patent documents, such as CN113122727A "A Method for Treating Steel Dust," employ a rotary kiln for primary reduction dezincification and a rotary hearth furnace for secondary reduction iron extraction. However, this method requires the addition of an extra carbon source, and the rotary hearth furnace process increases equipment investment and energy consumption. Furthermore, it lacks specific control measures for dioxin emissions and is only applicable to steel dust with a chlorine content ≤4%, resulting in limited raw material adaptability. Existing publicly available patent documents, such as CN109536729A "A Method for Utilizing Dust from Steel Smelting," involve classified treatment and recycling through different processes. Alkali metal dust is treated with water leaching, concentration, and crystallization to recover KCl / NaCl, with the leaching residue reused in sintering. Low-harm dust is directly returned to sintering. However, the water leaching process for high-alkali metal dust generates wastewater, requiring an additional wastewater treatment system. The roasting of high-zinc dust requires external heating, leading to high energy consumption. Moreover, the classified treatment process is complex, requiring multiple sets of equipment to work together, resulting in high investment costs. Summary of the Invention

[0005] In response to the aforementioned technical problems, a comprehensive utilization method for co-processing electric furnace dust in a dezincification rotary kiln is provided.

[0006] The technical means employed in this invention are as follows: A comprehensive utilization method for co-processing electric furnace dust from a zinc stripping rotary kiln includes the following steps: Step 1: Take samples of electric furnace dust and zinc-containing blast furnace dust separately, and test the contents of at least zinc, iron and chloride ions to determine the subsequent batching ratio of electric furnace dust and zinc-containing blast furnace dust. Step 2: Use sieving to remove large impurities from the pre-set electric furnace dust that are larger than the screen mesh size; perform magnetic separation pretreatment on the zinc-containing dust from the blast furnace to initially separate some ferromagnetic substances; then, dry both types of dust. Step 3: Based on the test results of Step 2, weigh the electric furnace dust and the blast furnace zinc-containing dust at a certain mass ratio, and then mix them thoroughly. Step 4: Feed the mixed material into the dezincification rotary kiln through a quantitative feeder. The dezincification rotary kiln is divided into at least two sections with different temperatures. The front section is a relatively low temperature zone and the rear section is a relatively high temperature zone. The temperature difference between the outlet temperature of the front section and the inlet temperature of the rear section is ≤50℃. Step 5: Collect the zinc-containing flue gas generated during calcination, condense it, and react it with oxygen in the air to generate secondary zinc oxide. At the same time, recover and treat the impurities and tail gas in the flue gas.

[0007] Furthermore, the saturated steam generated in step 4 is connected to the drying device in step 2.

[0008] Furthermore, in step 4, the high-temperature kiln slag discharged from the rotary kiln is connected to a water quenching cooler to crush the qualified kiln slag to a particle size of ≤5mm. The slag is then conveyed to the sintering batching system of the steel plant via a belt and added to the sintering mixture at a ratio of 5% to 8% to replace part of the iron ore powder.

[0009] Furthermore, the sieve in step 2 is a 100-200 mesh sieve.

[0010] Furthermore, in step 2, the two types of dust are dried. Specifically, the two types of dust are sent into a hot air dryer. The temperature of the hot air dryer is 60~80℃ and the wind speed is 1.2~1.5m / s. After drying for a certain period of time, the moisture content of the dried material is finally controlled to be ≤5%.

[0011] Furthermore, in step 3, the mass ratio of blast furnace dust and electric furnace dust is (8~9):(1~2). The actual mass ratio is adjusted based on the sampling results in step 1. The purpose of sampling is to test the carbon calorific value, Zn content, and Fe content of the two types of dust to ensure that the calorific value of the mixed material is stable at 1600~2000kcal / kg, which meets the self-sustaining combustion requirements without the need for external fuel during subsequent calcination.

[0012] Furthermore, in step 3, a composite additive of CaCl2 and Fe2O3, accounting for 0.5 to 1.5% of the total mass of the mixture, is added during the mixing process.

[0013] Furthermore, the temperature of the first low-temperature zone is controlled at 800~1000℃, the calcination time is greater than 60min, the kiln rotation speed is 0.8~1.2r / min, and the volume fraction of oxygen supplementation during the calcination process is 4%~5%; the temperature of the second high-temperature zone is controlled at 1100~1250℃, the calcination time is greater than 30min, the kiln rotation speed is 0.5~0.8r / min, and the volume fraction of oxygen supplementation during the calcination process is 3%~4%.

[0014] Furthermore, step 5 specifically includes the following steps: The zinc-containing flue gas produced by calcination first enters the waste heat boiler and is cooled to 300~350℃. Then it enters the cyclone dust collector to remove coarse dust particles from the flue gas. The cooled flue gas is sent to the bag filter dust collector, where zinc vapor condenses on the surface of the filter bag and reacts with oxygen in the air to generate secondary zinc oxide. The secondary zinc oxide product is obtained by pulse cleaning. The exhaust gas from the bag filter outlet first enters the activated carbon adsorption tower to adsorb residual dioxins and heavy metals, and then passes through the desulfurization tower to remove SO2.

[0015] Compared with existing technologies, this invention has the following advantages: This invention treats and recovers zinc and iron resources from electric furnace dust and zinc-containing blast furnace dust, achieving a high zinc recovery rate and high purity of secondary zinc oxide, which can be directly used as raw material for zinc smelting without further purification. This invention eliminates the need for additional equipment such as rotary hearth furnaces, water immersion tanks, and crystallization equipment. Through a single rotary kiln and gradient control, the calcination of mixed dust can be achieved without additional equipment, reducing energy consumption and cost per ton of processing, resulting in significant annual cost savings. This invention utilizes the high calorific value of blast furnace ash to achieve self-sustaining combustion, eliminating the need for external carbon sources, and requiring only a single rotary kiln to complete zinc removal and iron extraction, resulting in low equipment investment. Through multiple processes and the addition of a certain amount of composite additives, the generation and collection of various pollutants, including dioxins, are reduced, minimizing environmental pollution and achieving a reliable conversion of solid waste into usable resources. Furthermore, this invention employs a dry treatment process throughout, generating no wastewater and reducing wastewater treatment costs. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0022] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0023] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0024] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0025] like Figure 1 As shown in the figure, this invention discloses a method for the comprehensive utilization of electric furnace dust collected in conjunction with the dezincification rotary kiln, comprising the following steps: Step 1: Take samples of electric furnace dust and zinc-containing blast furnace dust separately, and test the contents of at least zinc, iron and chloride ions to determine the subsequent batching ratio of electric furnace dust and zinc-containing blast furnace dust. Among them, electric furnace dust has a low calorific value, with a carbon calorific value ≤200kcal / kg and a Zn content of about 15%~20%, while blast furnace zinc-containing dust has a high calorific value, with a carbon calorific value ≥2500kcal / kg and a Zn content of about 5%~8%.

[0026] Step 2: Use sieving to remove large impurities from the pre-set electric furnace dust that are larger than the screen mesh size; perform magnetic separation pretreatment on the zinc-containing dust from the blast furnace to initially separate some ferromagnetic substances; then, dry both types of dust. The sieve used in step 2 is a 100-200 mesh sieve.

[0027] In step 2, the two types of dust are dried. Specifically, the two types of dust are sent into a hot air dryer. The temperature of the hot air dryer is 60~80℃ and the wind speed is 1.2~1.5m / s. After drying for a certain period of time, the moisture content of the dried material is finally controlled to be ≤5%.

[0028] Step 3: Based on the test results of Step 2, weigh the electric furnace dust and the blast furnace zinc-containing dust at a certain mass ratio, and then mix them thoroughly. In step 3, the mass ratio of blast furnace dust and electric furnace dust is (8~9):(1~2). The actual mass ratio is adjusted based on the sampling results in step 1. The purpose of sampling is to test the carbon calorific value, Zn content, and Fe content of the two types of dust to ensure that the calorific value of the mixed material is stable at 1600~2000kcal / kg, which meets the self-sustaining combustion requirements without the need for external fuel during subsequent calcination.

[0029] Specifically, if the calorific value of electric furnace dust is too low, such as <150 kcal / kg, the blast furnace ash ratio can be adjusted upwards from 8:2 to 9:1 based on sampling data. This ensures that the calorific value of the mixed material remains stable at 1600~2000 kcal / kg, meeting the self-sustaining combustion requirements of subsequent gradient calcination without the need for additional fuel. Of course, if the Zn content in the furnace dust is too high, its ratio can be appropriately reduced after sampling to avoid excessive Zn enrichment in the kiln leading to secondary solidification. If the calorific value of the electric furnace dust is very low, even after proportioning, it still does not meet the standard, so a small amount of high-calorific-value auxiliary fuel, including pulverized coal, can be added. However, actual production has shown that the relatively fixed raw material sources, production processes, and dust removal systems of the electric furnace steelmaking plant determine the stability of the dust composition. The Zn, Fe, and chloride ions in the electric furnace dust mainly originate from scrap steel; stable raw materials result in a stable dust composition. Within the same plant area, the smelting power, smelting cycle, and slag-forming agent addition are relatively uniform, which will not lead to significant changes in the alkali metal and Fe oxide content in the dust collector ash. While the composition of the dust collector ash from electric furnaces within a plant area may fluctuate, the changes will not be substantial and will remain within a controllable range. These fluctuations mainly stem from minor adjustments to scrap steel batches and changes in smelting steel grades, but the fluctuation range is limited and can be assessed using the aforementioned sampling procedures. If the plant temporarily switches to smelting high-zinc steel grades, the Zn content in the electric furnace dust collector ash will exceed the normal value. By increasing the sampling frequency and adjusting the blast furnace ash ratio in a timely manner, the Zn content after mixing can be ensured to be compatible with the process, but this value generally will not exceed the aforementioned 8:2 ratio.

[0030] In step 3, a composite additive of CaCl2 and Fe2O3, comprising 0.5-1.5% of the total mass of the mixture, is added during the mixing process. In this embodiment, the mass ratio of CaCl2 to Fe2O3 is 1:2. The additive is first premixed with a small amount of blast furnace dust to form a masterbatch, and then fed into the mixer along with the remaining materials to ensure that the additive is evenly dispersed in the mixture and to avoid excessively high local concentrations that could lead to ring formation in the kiln.

[0031] Among them, CaCl2 can lower the reduction temperature of zinc compounds and promote the early volatilization of zinc in the relatively low-temperature zone. Fe2O3 acts as an oxygen carrier to regulate the oxygen content in the kiln and forms a stable compound with the harmful element Pb to inhibit its volatilization pollution. At the same time, the two work together to destroy the formation structure of dioxins and reduce the emission concentration.

[0032] Similarly, the purpose of collecting chloride ion content during the above sampling process is to ensure that excessive chloride ion content will lead to corrosion and accelerated ring formation of rotary kiln refractory materials. After confirming that the chloride ion content is within the preset range, corrosion is inhibited by composite additives. If the chloride ion content exceeds the preset range, other pretreatment measures need to be taken in advance to remove the chloride ions.

[0033] Of course, the sampling in step 1 may also include the analysis of heavy metals such as Pb. The sampling data can guide the adjustment of the amount of Fe2O3 added. Fe2O3 forms a stable compound with Pb, thus avoiding secondary pollution caused by the volatilization of Pb with flue gas.

[0034] Step 4: The mixed material is fed into the dezincification rotary kiln through a quantitative feeder. The dezincification rotary kiln is divided into at least two sections with different temperatures. The front section is a relatively low temperature zone and the rear section is a relatively high temperature zone. The temperature difference between the outlet of the front section and the inlet of the rear section is ≤50℃. During the entire heating process, the pressure inside the kiln is maintained at -10~-20Pa to ensure that zinc vapor flows towards the kiln head to avoid reverse diffusion that could lead to zinc loss.

[0035] The temperature of the initial low-temperature zone is controlled at 800~1000℃, the calcination time is greater than 60min, the kiln rotation speed is 0.8~1.2r / min, and the volume fraction of oxygen supplementation during calcination is 4%~5%; the initial outlet temperature refers to the actual temperature of the material after being heated in the initial low-temperature zone for ≥60min and leaving the initial zone, about to enter the subsequent zone. This temperature needs to be close to the upper limit of the initial zone to ensure that the volatile zinc compounds have been fully pre-removed; The temperature in the high-temperature zone of the rear section is controlled at 1100~1250℃, the calcination time is greater than 30 minutes, the kiln rotation speed is 0.5~0.8 r / min, and the volume fraction of oxygen supplementation during calcination is 3%~4%. The inlet temperature of the rear section refers to the initial temperature of the material when it first enters the rear section, and this temperature needs to be based on the outlet temperature of the front section. After the material enters the rear section, it is gradually heated to the target range of 1100~1250℃ through the heating system of the rotary kiln. The heating process of the material in the low-temperature zone of the front section is a gradual increase in temperature, from the initial feed temperature to 800~1000℃, and stabilizes at a temperature close to the upper limit of the front section at the end of the front section, just before entering the rear section. At this time, the pre-removal rate of volatile zinc compounds has reached more than 70%. Because a rotary kiln is a continuously operating cylindrical device with no physical separation between the front and rear sections, the temperature of the material entering from the front end to the rear end will not drop or rise abruptly. If the outlet temperature of the front section is 1000℃, the inlet temperature of the rear section can be maintained at 1000~1050℃ through the transition heating section of the kiln body, with a temperature difference of ≤50℃, avoiding thermal shock caused by sudden temperature changes in the material. This temperature difference control can effectively prevent low-melting-point substances in the material from suddenly melting and adhering to the kiln wall due to a sudden temperature rise. Specifically, if the temperature fluctuation is too large, SiO2 and CaO in the material are prone to form low-melting-point glass, which adheres to the kiln wall and forms a ring, making subsequent processing very troublesome. Even with the above measures, ring formation may still occur. As an extended implementation method, the kiln wall can be sprayed with an anti-ring coating to extend the service life of the equipment.

[0036] In this embodiment, the zinc stripping rotary kiln has a diameter of 3.0m, a length of 35m, and a kiln body inclination of 5°. The front section accounts for 2 / 3 of the total kiln length and is heated by hot air from the kiln tail. The rear section accounts for 1 / 3 of the total kiln length and is heated by natural gas burners at the kiln head. The burner power is adjusted in real time through a temperature control system to ensure that the temperature difference between the outlet temperature of the front section and the inlet temperature of the rear section is ≤50℃.

[0037] The gradient heating design of this invention not only meets the requirements for zinc removal but also effectively prevents ring formation on the equipment.

[0038] The core function of the first low-temperature zone is pre-zinc removal, which targets volatile zinc compounds in electric furnace dust, such as ZnCl2 and simple ZnO, and achieves initial volatilization within this temperature range, while preventing low-melting-point substances, such as CaO-SiO2-ZnO, from premature melting and ring formation. The core function of the second high-temperature zone is deep zinc removal, which targets difficult-to-reduce zinc compounds and completely reduces and volatilizes them through higher temperatures.

[0039] During the calcination process described above, samples can be taken at any time to test the proportion of Zn in the form of ZnO and ZnFe2O4, as well as the type of Fe oxide. If the sample shows that the proportion of ZnFe2O4 exceeds 70%, it indicates that the reduction is relatively difficult, and the content of CaCl2 auxiliary agent should be adjusted accordingly.

[0040] The saturated steam generated in step 4 is connected to the drying device in step 2, thus utilizing one instance of waste heat. If the plant is connected to a power generation system, the pipeline can be modified to send the saturated steam into a steam turbine generator set.

[0041] As another material utilization, the high-temperature kiln slag discharged from the rotary kiln in step 4 is connected to a water quenching cooler to crush the qualified kiln slag to a particle size of ≤5mm. It is then conveyed to the sintering batching system of the steel plant via a belt and added to the sintering mixture at a ratio of 5% to 8% to replace part of the iron ore powder.

[0042] Step 5: Collect the zinc-containing flue gas generated during calcination, condense it, and react it with oxygen in the air to generate secondary zinc oxide. At the same time, recover and treat the impurities and tail gas in the flue gas.

[0043] Step 5 specifically includes the following steps: The zinc-containing flue gas generated during calcination first enters a waste heat boiler, where it is cooled to 300-350°C to recover a certain amount of waste heat. Then, it enters a cyclone dust collector to remove coarse dust particles from the flue gas. The cooled flue gas is then sent to a bag filter dust collector, where zinc vapor condenses on the surface of the filter bags and reacts with oxygen in the air to generate secondary zinc oxide. The secondary zinc oxide product is collected by pulse cleaning. In this embodiment, the ZnO obtained according to the above process is ≥65%, which meets the industrial-grade zinc oxide raw material standard. The exhaust gas from the bag filter outlet first enters the activated carbon adsorption tower to adsorb residual dioxins and heavy metals, and then passes through the desulfurization tower to remove SO2.

[0044] Example 1 Raw material parameters: Electric furnace dust, Zn 19.8%, Fe 29.7%, Cl⁻ 2.1%, carbon calorific value 180 kcal / kg; Blast furnace zinc-containing dust, Zn 5.2%, Fe 23.5%, Cl⁻ 0.3%, carbon calorific value 2600 kcal / kg). Batching ratio: Blast furnace dust: Electric furnace dust = 9:1, with 1.0% composite additive (CaCl2:Fe2O3 = 1:2). Rotary kiln parameters: front section temperature 950℃, time 60min, rotation speed 1.0r / min, oxygen content 4%; rear section temperature 1200℃, time 30min, rotation speed 0.8r / min, oxygen content 3.5%; kiln pressure -15Pa. Zinc recovery rate: 89.7%; Zinc oxide quality: ZnO 68.3% Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A comprehensive utilization method for the co-processing of electric furnace dust from a zinc stripping rotary kiln, characterized in that, Includes the following steps: Step 1: Take samples of electric furnace dust and zinc-containing blast furnace dust separately, and test the contents of at least zinc, iron and chloride ions to determine the subsequent batching ratio of electric furnace dust and zinc-containing blast furnace dust. Step 2: Use sieving to remove large impurities from the pre-set electric furnace dust that are larger than the screen mesh size; perform magnetic separation pretreatment on the zinc-containing dust from the blast furnace to initially separate some ferromagnetic substances; then, dry both types of dust. Step 3: Based on the test results of Step 2, weigh the electric furnace dust and the blast furnace zinc-containing dust at a certain mass ratio, and then mix them thoroughly. Step 4: Feed the mixed material into the dezincification rotary kiln through a quantitative feeder. The dezincification rotary kiln is divided into at least two sections with different temperatures. The front section is a relatively low temperature zone and the rear section is a relatively high temperature zone. The temperature difference between the outlet temperature of the front section and the inlet temperature of the rear section is ≤50℃. Step 5: Collect the zinc-containing flue gas generated during calcination, condense it, and react it with oxygen in the air to generate secondary zinc oxide. At the same time, recover and treat the impurities and tail gas in the flue gas.

2. The method according to claim 1, characterized in that, The saturated steam generated in step 4 is connected to the drying device in step 2.

3. The method according to claim 1, characterized in that, In step 4, the high-temperature kiln slag discharged from the rotary kiln is connected to a water quenching cooler to crush the qualified kiln slag to a particle size of ≤5mm. The slag is then conveyed to the sintering batching system of the steel plant via a belt and added to the sintering mixture at a ratio of 5% to 8% to replace part of the iron ore powder.

4. The method according to claim 1, characterized in that, The sieve used in step 2 is a 100-200 mesh sieve.

5. The method according to claim 1, characterized in that, In step 2, the two types of dust are dried. Specifically, the two types of dust are sent into a hot air dryer. The temperature of the hot air dryer is 60~80℃ and the wind speed is 1.2~1.5m / s. After drying for a certain period of time, the moisture content of the dried material is finally controlled to be ≤5%.

6. The method according to claim 1, characterized in that, In step 3, the mass ratio of blast furnace dust and electric furnace dust is (8~9):(1~2). The actual mass ratio is adjusted based on the sampling results in step 1. The purpose of sampling is to test the carbon calorific value, Zn content, and Fe content of the two types of dust to ensure that the calorific value of the mixed material is stable at 1600~2000kcal / kg, which meets the self-sustaining combustion requirements without the need for external fuel during subsequent calcination.

7. The method according to claim 1, characterized in that, In step 3, a composite additive of CaCl2 and Fe2O3, accounting for 0.5 to 1.5% of the total mass of the mixture, is added during the mixing process.

8. The method according to claim 1, characterized in that, The temperature in the initial low-temperature zone is controlled at 800~1000℃, the calcination time is greater than 60min, the kiln rotation speed is 0.8~1.2r / min, and the volume fraction of oxygen supplementation during calcination is 4%~5%; the temperature in the subsequent high-temperature zone is controlled at 1100~1250℃, the calcination time is greater than 30min, the kiln rotation speed is 0.5~0.8r / min, and the volume fraction of oxygen supplementation during calcination is 3%~4%.

9. The method according to claim 1, characterized in that, Step 5 specifically includes the following steps: The zinc-containing flue gas produced by calcination first enters the waste heat boiler and is cooled to 300~350℃. Then it enters the cyclone dust collector to remove coarse dust particles from the flue gas. The cooled flue gas is sent to the bag filter dust collector, where zinc vapor condenses on the surface of the filter bag and reacts with oxygen in the air to generate secondary zinc oxide. The secondary zinc oxide product is obtained by pulse cleaning. The exhaust gas from the bag filter outlet first enters the activated carbon adsorption tower to adsorb residual dioxins and heavy metals, and then passes through the desulfurization tower to remove SO2.

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