Method for treating zinc-containing dust by layered material pre-reduction sintering

Abstract

The application provides a method for treating zinc-containing dust by layered distribution of raw materials for pre-reduction sintering, which comprises distributing carbon-containing high-zinc dust pellets to the lower part of a sintering trolley through a distribution device, distributing low-zinc dust pellets to the upper part of the sintering trolley after mixing with sintering matrix materials, and sintering by air draft, so that sinter is prepared in the upper layer and pre-reduction furnace materials are prepared in the lower layer by zinc removal through reduction. In the application, the high-zinc dust and the low-zinc dust are distributed in different sintering mixture layers, so that temperature control and partition reaction are realized, sinter is prepared in the upper layer at the same time, deep reduction and zinc removal of the high-zinc dust are realized in the lower layer, qualified sinter and low-zinc pre-reduction furnace materials are obtained at last, the collaborative treatment of zinc-containing dust is effectively realized, the quality of the sinter and the pre-reduction efficiency are improved, and high-quality low-carbon furnace materials are provided for blast furnace smelting.

Description

Technical Field

[0001] This invention belongs to the field of sintering technology in iron and steel metallurgy, and particularly relates to a method for the co-processing of zinc-containing dust by layered pre-reduction sintering, which is applicable to the resource utilization of zinc-containing dust, the improvement of sinter quality, and the control of zinc emissions. Background Technology

[0002] In the steel production process, a large amount of zinc-containing dust (such as blast furnace dust and converter dust) is generated. High-zinc dust has a high zinc content, and direct treatment can easily cause environmental pollution and resource waste. Although low-zinc dust can be partially recovered, the uniform mixing of materials in traditional sintering processes leads to problems such as poor air permeability and low zinc removal efficiency. At the same time, although there are attempts at pre-reduction sintering in existing technologies, they have not achieved layered material distribution to coordinate the treatment of dust with different properties, and cannot optimize the material layer structure, fuel distribution and flue gas emissions, thus limiting sintering efficiency and product quality.

[0003] Therefore, there is an urgent need for an efficient layered sintering method to achieve the synergistic treatment of high-zinc dust reduction and removal and low-zinc dust sintering. Summary of the Invention

[0004] The main objective of this invention is to provide a method for the co-processing of zinc-containing dust in layered pre-reduction sintering, in order to solve the problems of poor air permeability, incomplete zinc removal, and low fuel utilization caused by the mixing of dust with different properties, thereby realizing the resource utilization of dust, improving the quality of sinter and pre-reduction furnace feed, and achieving the simultaneous utilization of high-zinc and low-zinc dust.

[0005] To achieve the above objectives, the present invention provides a method for the co-processing of zinc-containing dust by layered fabric pre-reduction sintering, comprising the following steps: S1. Material preparation: Prepare high-zinc dust internal carbon pellets, low-zinc dust pellets, and sintering base material respectively; S2. Fabric distribution: A layered fabric distribution device is adopted, in which high-zinc dust carbon-containing pellets are distributed in the lower layer of the sintering trolley, and low-zinc dust pellets are mixed with the sintering base material and distributed in the upper layer of the sintering trolley. S3. Sintering: The upper and lower material layers in the layered feeding device are ignited and sintered from top to bottom to obtain the upper layer of sintered ore and the lower layer of low-zinc pre-reduction furnace charge.

[0006] Furthermore, the zinc content of the carbon-containing pellets in the high-zinc dust is 5-40% of the mass of the carbon-containing pellets in the high-zinc dust, and the amount of carbon is 10-20% of the mass of the carbon-containing pellets in the high-zinc dust; The zinc content of the low-zinc dust pellets is 0.01 to 5% of the mass of the low-zinc dust pellets.

[0007] Furthermore, in step S2, the mass ratio of low-zinc dust pellets to sintered base material is (0.05~0.3):1.

[0008] Further, in step S2, the basicity of the high-zinc dust with carbon-containing pellets is 0-1; the basicity of the low-zinc dust pellets is 0-1; and the sputtering of the sintering base material is 1.5-2.5.

[0009] Furthermore, in step S3, the total height of the upper and lower material layers is 300-1000mm, and the height ratio of the upper material layer to the lower material layer is 1:(2-0.1).

[0010] Furthermore, the feeding layer also contains fuel, and the fuel content in the feeding layer is 2 to 5% of the total mass of the low-zinc dust pellets and sintered base material.

[0011] Furthermore, the moisture content of the feed layer is 4-12% of the total mass of the low-zinc dust pellets and sintered base material; The moisture content of the feed layer is 4-15% of the mass of the carbon pellets in the high-zinc dust.

[0012] Furthermore, in step S3, the ignition temperature is 1050–1100℃, the ignition time is 60–90s, the sintering negative pressure is 6–20kPa, and the sintering machine speed is 1–4m / min.

[0013] Furthermore, the particle size of the carbon pellets in the high-zinc dust is 5-50 mm; The particle size of the low-zinc dust pellets is 6–14 mm.

[0014] Furthermore, the layered fabric distribution device also includes a height sensor and an automatic control system, which are used to adjust the thickness ratio of the upper and lower layers in real time, with the thickness accuracy controlled within ±5mm.

[0015] The beneficial effects of this invention are as follows: Optimized air permeability: The layered material distribution device (double-layer structure) distributes high-zinc dust with carbon pellets in the lower layer of the sintering trolley, utilizing the heat storage effect of sintering to promote its pre-reduction, while effectively improving the air permeability of the overall material layer, increasing the air permeability by 20-35%.

[0016] Highly efficient zinc removal: The zinc reduction rate of the high-zinc dust in the feed layer with carbon pellets is over 98%, and the zinc removal rate is greater than 92%, achieving highly efficient separation of zinc and iron.

[0017] Improving product quality: The drum strength of the sinter obtained from the sintering of the upper layer is greater than 65%; the metallization rate of the pre-reduced furnace charge obtained from the pyrolysis reduction of the lower layer is increased by 5-20% compared with the traditional process, providing high-quality furnace charge for the blast furnace, and the utilization rate of high zinc dust reaches more than 95%, which significantly reduces the emission of metallurgical solid waste and realizes the recycling of resources and environmental protection.

[0018] This invention employs a synergistic treatment of low-zinc dust sintering and high-zinc dust pre-reduction. Utilizing the high-carbon heat storage effect of carbon pellets within the bottom layer of high-zinc dust, harmful elements such as lead and zinc in the dust are fully reduced and volatilized, while effectively decreasing the carbon content of the sintered matrix material. This significantly reduces solid fuel consumption during sintering and lowers production costs. The invention also features a matching layered material distribution device to improve distribution accuracy, and combined with automated control, reduces human error, ensuring process stability and repeatability. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0021] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0022] This invention provides a method for co-processing zinc-containing dust using layered fabric pre-reduction sintering, comprising the following steps: S1. Material preparation: Prepare high-zinc dust carbon pellets, low-zinc dust pellets, and sintering base material respectively.

[0023] In this invention, the zinc content of the carbon-coated high-zinc dust pellets is 5-40% of the mass of the high-zinc dust-coated high-zinc dust pellets. This allows the lower layer of high-zinc dust-coated high-zinc pellets to achieve a higher zinc removal rate and a higher metallization rate of the pre-reduced furnace charge, ensuring the consolidation quality of the upper sintered ore. Simultaneously, it leverages the heat storage and energy saving advantages of the lower layer, achieving an optimal balance between zinc removal efficiency, product quality, and cost. If the zinc content is too high (>40%), the reduction of the lower layer of high-zinc dust-coated high-zinc pellets requires a large amount of carbon and heat, and excessive heat absorption can easily lead to "overcooling" of the material layer and incomplete reduction reaction, resulting in a significant decrease in the zinc removal rate and the metallization rate of the pre-reduced furnace charge. This also damages the consolidation quality of the upper sintered ore, causing process failure. If the zinc content is too low (<5%), direct mixing and sintering can meet the zinc removal requirements. Using the complex processes of layered material distribution and separate pelletizing as described in this invention would increase equipment and operating costs, losing economic rationality and failing to leverage the heat storage and energy saving advantages of the lower layer of high-carbon pellets.

[0024] In this invention, the amount of internally added carbon in the high-zinc dust internally added carbon pellets is 10-20% of the mass of the high-zinc dust internally added carbon pellets, mainly used to control the strength of the reducing atmosphere and heat supply. If the internally added carbon content is too high, energy consumption will increase and the residual carbon in the pre-reduction furnace charge will be high; if the internally added carbon content is too low, the reduction will be incomplete, resulting in a significant decrease in the zinc removal rate. The internally added carbon here refers to the carbon reducing agent or carbon-containing material mentioned below.

[0025] The zinc content of the low-zinc dust pellets is 0.01-5% of the mass of the low-zinc dust pellets, which can ensure the low-zinc quality of the upper sintered ore products.

[0026] In some embodiments of the present invention, the high-zinc dust internally carbonized pellets are prepared by mixing high-zinc dust, carbon reducing agent (i.e., the internally added carbon mentioned above), and a first binder, adding water to bring the moisture content of the mixture to 4-15%, then feeding it into a strong mixing device for uniform mixing, and then feeding it into a briquetting machine to produce pellets with a particle size of 5-50 mm under conditions of pressure of 20-28 t, rotation speed of 10-15 r / min, and roller gap distance of 3-8 mm. In the present invention, if the particle size of the high-zinc pellets (i.e., high-zinc dust internally carbonized pellets) is too large, it will lead to incomplete reduction and a decrease in the zinc removal rate; if the particle size of the high-zinc pellets is too small, it will lead to a decrease in air permeability and an increase in airflow resistance, thereby affecting the zinc removal rate, sinter quality, and other properties.

[0027] The high-zinc dust has a zinc oxide content >10%, a static sphericity index K >0.6, and an average particle size >1mm, ensuring good sphericity. When distributed in the lower layer of the sintering trolley, it forms a stable porous structure, improving the permeability of the lower layer and ensuring a high zinc removal rate and metallization rate. The carbon reducing agent is a carbon-containing material, added at 10-20% of the mass of the carbon pellets in the high-zinc dust. Preferably, the carbon reducing agent is coke powder with a particle size less than 1mm. The first binder is added at 1.25-2.5% of the mass of the carbon pellets in the high-zinc dust. Preferably, the first binder is bentonite, added at 1.5%.

[0028] In some embodiments of the present invention, the low-zinc dust pellets are prepared by mixing a first iron-containing raw material, low-zinc dust, fuel powder, and a second binder, and then rolling them three times at a rolling pressure of 2.0–4.0 N / mm. 2 The mixture is then thoroughly mixed in a strong mixer and finally fed into a pelletizing pan. Water is added until the moisture content of the mixture is 7-10%. Granulation is carried out at an inclination angle of 40°-50° and a rotation speed of 8Hz for 12-16 minutes, producing pellets with a particle size of 6-14mm. In this invention, if the particle size of the low-zinc dust pellets is too large, it will cause uneven sinter structure; if the particle size of the low-zinc dust pellets is too small, it will easily pulverize and affect the upper layer consolidation. Therefore, controlling the particle size of both the high-zinc dust internally carbonized pellets and the low-zinc dust pellets can ensure good air permeability and efficient reaction during the processing of this invention.

[0029] The low-zinc dust has a zinc oxide content of <3.0% and an average particle size of <0.6mm, ensuring a low zinc content in the low-zinc dust pellets and thus avoiding affecting the quality of the sinter. The amount of low-zinc dust added is 10-20% of the mass of the low-zinc dust pellets, preferably 15%; the amount of fuel powder added is 1.0-6.0% of the mass of the low-zinc dust pellets, preferably coke powder with a particle size of less than 0.075mm; the amount of the second binder added is 1.0-2.0% of the mass of the low-zinc dust pellets, preferably bentonite, with an addition amount of 1.5%.

[0030] Preparation of sintering base material: By mass, 60-80 parts of the second iron-containing raw material, 10-30 parts of return ore, 2-8 parts of dolomite, 2-8 parts of quicklime, and 3-5 parts of coke powder (or other fuels) are mixed. Water is added to adjust the moisture content of the mixture to 6-10%, preferably 8%. The mixture is then fed into a cylindrical mixer for granulation for 3-8 minutes, preferably 5 minutes, to obtain the sintering base material. The coke powder has a fixed carbon content of 82.75% and a particle size <0.075 mm; the basicity of the sintering base material is 1.5-2.5, preferably 2.0.

[0031] In this invention, the fuel content in the upper layer (referring to the sum of fuel fines in the low-zinc dust pellets and coke powder in the sintering base material) is 2-5% of the total mass of the low-zinc dust pellets and the sintering base material, ensuring that the upper layer of sinter receives a sufficient oxidizing atmosphere and liquid phase. Insufficient fuel will lead to insufficient sinter strength, while excessive fuel will cause overmelting and decreased reducibility. Preferably, the fuel is coke powder with a content of 4 wt% and a particle size <0.075 mm.

[0032] In this invention, the basicity of the sintering matrix is ​​1.5–2.5, the basicity of the high-zinc dust-coated carbon pellets is 0–1, and the basicity of the low-zinc dust pellets is 0–1. These differences in basicity are beneficial to forming a composite structure of “high-basicity, easily solidified matrix material in the upper layer + low-basicity, overmelting resistant pellets”. The higher basicity of the sintering matrix is ​​conducive to the reaction of CaO with iron oxides, SiO2, etc., to form an appropriate amount of calcium ferrite and silicate liquid phase, thereby improving the bonding strength and yield of the upper sintered ore. The lower basicity of the high-zinc dust-coated carbon pellets and the low-zinc dust pellets can prevent the pellets from forming a low-melting-point liquid phase too early in the initial stage of sintering, which would lead to the collapse of the pellet structure. This is beneficial to maintaining the pore structure of the pellets, the reducing atmosphere, and the zinc vapor discharge channels.

[0033] If the basicity of the sintering base material is too low, insufficient liquid phase generation will occur, leading to a decrease in the consolidation strength of the upper sinter. If the basicity of the sintering base material is too high, excessive liquid phase will easily cause overmelting, reduced permeability of the material layer, and affect the discharge of zinc vapor from the lower layer. If the basicity of high-zinc dust with carbon-containing pellets or low-zinc dust pellets is too high, the pellets are prone to premature softening and melting, causing pore blockage and reducing the zinc removal rate and pre-reduction effect. If the basicity of the pellets is too low, insufficient liquid bonding between the pellets and the surrounding sintering base material may reduce the overall strength of the sinter. Therefore, this invention achieves both upper sinter consolidation and lower layer reduction dezincification through the above-mentioned basicity matching.

[0034] In some embodiments of the present invention, the first iron-containing raw material and the second iron-containing raw material have the same composition, both being iron concentrate. Preferably, the iron concentrate is selected from Canadian iron concentrate, pelletized iron concentrate and Tiangao iron concentrate in a mass ratio of 6.9:5.9:7.1.

[0035] S2. Material distribution: A layered material distribution device is adopted, in which high-zinc dust carbon-containing pellets are distributed in the lower layer of the sintering trolley, and low-zinc dust pellets are mixed with the sintering base material and distributed in the upper layer of the sintering trolley.

[0036] In some embodiments of this invention, the mass ratio of low-zinc dust pellets to sintering base material is 0.05–0.3:1. If too many low-zinc dust pellets are added, the enrichment of harmful elements such as zinc will lead to a decrease in the quality of the sinter (excessive ZnO, reduced strength); if too few low-zinc dust pellets are added, the dust cannot be effectively absorbed, the synergistic treatment is lost, and the permeability of the upper layer may deteriorate. Therefore, this invention needs to control the mass ratio within the range of 0.05–0.3:1 to balance sinter performance and dust treatment capacity.

[0037] In this invention, the layered material distribution device includes a lower layer material distribution device and an upper layer material distribution device, ensuring that the materials in the upper and lower layers do not mix and are evenly distributed. In actual operation, the material distribution method uses a circular roller to ensure that the layers do not mix and are evenly distributed.

[0038] S3. Sintering: The upper and lower material layers (i.e., upper material layer + lower material layer) of the layered material feeding device are ignited and sintered from top to bottom. The upper mixed material is solidified and formed under a high-temperature oxidizing atmosphere to generate sinter with qualified strength. The lower high-zinc dust mixed with carbon pellets undergoes pyrolysis reduction reaction under the high temperature of sintering and the reducing atmosphere generated by the carbonaceous reducing agent. Zinc and its oxides are reduced to zinc vapor and removed with the flue gas, and a pre-reduced furnace charge with a high degree of metallization is obtained simultaneously. During the sintering process, the temperature gradient and atmosphere difference from top to bottom of the material layer are used to achieve the coordinated sintering and solidification of the upper layer and the reduction and dezincification of the lower layer. The flue gas is treated by dust collection to recover the zinc component. After sintering, qualified sinter and low-zinc pre-reduced furnace charge are obtained respectively.

[0039] In this invention, "temperature gradient" refers to the temperature distribution that decreases sequentially from the upper to the lower material layer: the upper ignition zone has the highest temperature (1200-1300℃, which is the peak temperature that the upper sintering liquid phase generation zone can reach when the combustion zone passes through the upper material after ignition), which is conducive to the generation and solidification of the sintered ore liquid phase. The lower layer has a lower temperature (approximately 1000-1100℃) due to the heat absorption of the reduction reaction and its distance from the ignition source, which just meets the requirements for the reduction and removal of zinc oxides. "Atmosphere difference" refers to the fact that the upper layer is in an oxidizing atmosphere (sufficient O2) formed by the intake of air, which promotes the oxidation of iron oxides to hematite and the formation of sintered ore. The lower layer has a reducing atmosphere (high CO / CO2) formed by the combustion and reduction reaction of internal carbon, which reduces ZnO to Zn vapor and is discharged with the flue gas. The two work together to achieve the simultaneous occurrence of upper-layer sintering and lower-layer reduction and dezincification.

[0040] In this invention, the total height of the upper and lower material layers is 300–1000 mm, and the height ratio of the upper to lower material layers is 1:(2–0.1) to ensure the synergistic effect of high-quality sinter in the upper layer and efficient dezincification in the lower layer. If the total height of the upper and lower material layers is less than 300 mm, it will lead to insufficient heat storage and incomplete reduction; if the total height is greater than 1000 mm, the permeability will deteriorate and sintering will be difficult. In this invention, if the proportion of the lower material layer is too high, it will lower the material temperature due to excessive heat absorption; if the proportion is too low, the amount of high-zinc dust to be processed will be small, and the reducing atmosphere in the lower layer will be easily destroyed.

[0041] In this invention, the moisture content of the upper layer is 4-12% of the total mass of low-zinc dust pellets and sintered base material; the moisture content of the lower layer is 4-15% of the mass of high-zinc dust carbon-coated pellets.

[0042] The moisture content here refers to the percentage by mass of water added during pelleting or mixing of the raw materials. If the moisture content is too low, the pellets will lack strength, easily pulverize, and the permeability of the material layer will deteriorate, while also affecting the rate of liquid phase formation and reduction reaction. If the moisture content is too high, it will severely hinder ventilation, preventing the sintering process from proceeding normally, and may even cause "flameout." This invention controls the moisture content of the upper layer at 4–12% and the lower layer at 4–15% to ensure good pellet strength, suitable permeability of the material layer, and stable sintering and reduction reactions.

[0043] In this invention, the ignition temperature is 1050–1150℃, the ignition time is 60–90s, the sintering negative pressure (i.e., the exhaust negative pressure) is 6–20kPa, and the sintering machine speed is 1–4m / min. This ensures that the upper layer obtains qualified sintered ore while simultaneously guaranteeing efficient zinc removal in the lower layer. In this invention, if the sintering negative pressure is too low, it will lead to insufficient exhaust, a decrease in the reduction zinc removal rate, and a reduction in output; if the sintering negative pressure is too high, the upper layer of sintered ore will cool too quickly, resulting in decreased strength, and will also affect zinc vapor recovery.

[0044] In this invention, the layered fabric distribution device also includes a height sensor and an automatic control system, which are used to adjust the thickness ratio of the upper and lower layers in real time, with the thickness accuracy controlled within ±5mm.

[0045] In this invention, the chemical composition of the sintered ore product includes: TFe content of 56.0-58.5%, FeO content of 8.0-9.5%, SiO2 content of 5.5-5.8%, Al2O3 content of 1.8-1.9%, CaO content of 10.8-11.8%, MgO content of 1.6-2.0%, K2O content of 0.03-0.05%, Na2O content of 0.05-0.07%, P content of 0.06-0.08%, S content of 0.01-0.03%, Pb content <0.0001%, and Zn content of 0.02-0.05%. This indicates that by using the low-zinc dust sintering-high-zinc dust pre-reduction synergistic treatment method, the upper layer material after sintering (i.e., low-zinc sintered material) can obtain high-grade, high-strength, high-reducibility, and excellent impurity control quality sintered ore, which is suitable for blast furnace production.

[0046] The method for co-processing zinc-containing dust by layered fabric pre-reduction sintering according to the present invention will be described below with reference to specific embodiments.

[0047] The main chemical composition, particle size distribution, and distribution of the dust (i.e., high-zinc dust and low-zinc dust) used in this invention are shown in Tables 1 and 2 below.

[0048] Table 1. Main chemical components of dust collector dust (%) Table 1. Main chemical components of dust (continued) / % Table 2. Particle size composition and distribution of dust collector ash / % The main chemical components of the iron concentrate and recycled ore used in this invention are shown in Table 3 below.

[0049] Table 3. Main chemical components of iron concentrate and return ore / % The main chemical components of the solvents (dolomite and quicklime) used in this invention are shown in Table 4 below.

[0050] Table 4. Main chemical components of the solvent / % The physical properties of the bentonite used in this invention are shown in Table 5 below.

[0051] Table 5 Physical properties of bentonite Example 1 A method for co-processing zinc-containing dust through layered fabric pre-reduction sintering is as follows: S1. Material preparation: Prepare high-zinc dust with carbon pellets (zinc content of 10%) with an average particle size of 20mm, low-zinc dust pellets (zinc content of 3%) with a particle size of 6-8mm, and sintering base material.

[0052] Preparation of low-zinc dust pellets: By mass percentage, 73.5% mixed iron concentrate (composed of Canadian concentrate, pelletizing concentrate and Tiangao concentrate in a mass ratio of 6.9:5.9:7.1), 15% low-zinc dust (hexa-gravity ash and electrical steel ash in a mass ratio of 2.48:1), 3% coke powder (fixed carbon 82.75%, particle size <0.075mm) and 1.5% bentonite were mixed, rolled three times, and then mixed evenly in a strong mixer. Finally, the mixture was fed into a pelletizing pan, and water was added until the moisture content of the mixture was 7%. Granulation was carried out at an inclination angle of 45° and a rotation speed of 8Hz for 12 minutes to produce pellets with a particle size of 6-8mm and an alkalinity of 0.1.

[0053] Preparation of high-zinc dust with internal carbonized pellets: 70.5% high-zinc dust (converter ash and zinc-containing ash in a mass ratio of 94.59:5.41), 15% coke powder (fixed carbon 82.75%, particle size <0.075mm) and 1.5% bentonite were mixed by mass percentage. Water was added until the moisture content of the mixture was 13%. The mixture was then fed into a strong mixing device for uniform mixing, and then fed into a briquetting machine. Under the conditions of pressure of 24t, rotation speed of 11r / min and roller gap of 5mm, pellets with an average particle size of 20mm and an alkalinity of 0.15 were produced.

[0054] Preparation of sintering base material: 68.5 parts iron ore, 15 parts recycled ore, 5 parts dolomite, 8 parts quicklime, and 3.5 parts coke powder were mixed by dry weight; wherein the coke powder had a fixed carbon content of 82.75% and a particle size <0.075mm. Water, accounting for 8% of the total dry weight of the sintering base material, was then added, and the mixture was granulated after thorough mixing to obtain the sintering base material with a basicity of 2.0.

[0055] S2. Material distribution: A layered material distribution device is adopted, in which 100kg of high zinc dust mixed with carbon pellets is distributed in the lower layer of the sintering trolley at a height of 200mm; 28kg of low zinc dust pellets and 172kg of sintering base material are mixed and distributed in the upper layer of the sintering trolley at a height of 600mm, that is, the height ratio of the lower layer material to the upper layer material is 1:3.

[0056] S3. Sintering: The upper and lower material layers after the material is fed in the layered feeding device are ignited and sintered from top to bottom. The ignition time is 90s, the negative pressure of the exhaust is 10kPa, the ignition temperature is 1100℃, and the sintering machine speed is 3m / min, to obtain the upper layer of sintered ore and the lower layer of low zinc pre-reduction furnace material.

[0057] Tests showed that the sinter contained 58% TFe, <0.5% ZnO, and 66.63% drum strength; the zinc removal rate in the low-zinc pre-reduction furnace charge was 90%, and the metallization rate was 95%.

[0058] Example 2 Unlike Example 1, in Example 2, the total height of the upper and lower layers is 500mm, and the height ratio of the lower layer to the upper layer is 1:3.

[0059] Tests showed that the sinter contained 58.3% TFe, <1.0% ZnO, and 57.83% drum strength; the zinc removal rate in the low-zinc pre-reduction furnace charge was 85%, and the metallization rate was 82%.

[0060] Example 3 Unlike Example 1, the height ratio of the lower layer material to the upper layer material in Example 3 is 1:1.

[0061] Tests showed that the sinter contained 57.6% TFe, 1.5% ZnO, and 55.92% drum strength; the zinc removal rate in the low-zinc pre-reduction furnace charge was 82%, and the metallization rate was 78%.

[0062] Comparative Example 1 (Traditional Hybrid Sintering) Unlike Example 1, this comparative example does not use the layered fabric distribution device of the present invention; instead, it directly mixes and sintersperses high-zinc dust with carbon-containing pellets and low-zinc dust pellets uniformly.

[0063] Tests showed that the obtained sinter contained 56% TFe, 3% ZnO, and 49.2% drum strength; the zinc removal rate was 60%, and the metallization rate was 40%.

[0064] Comparative Example 2 (reduced fuel ratio) Unlike Example 1, the content of internal carbon (i.e. coke powder with 82.75% fixed carbon and a particle size of <0.075mm) in the high-zinc dust internal carbon pellets in this comparative example is reduced to 15%.

[0065] Tests showed that the obtained sinter contained 41% TFe, 5% ZnO, and 50.3% drum strength; the zinc removal rate was 30%, and the metallization rate was 30%.

[0066] Comparative Example 3 (High zinc content in carbon pellets mixed with high zinc dust) Unlike Example 1, this comparative example increases the zinc content in the carbon-coated pellets within the high-zinc dust to 43%, while the remaining conditions are the same as in Example 1.

[0067] The obtained sinter contained 52.5% TFe, 2.8% ZnO, and 53.6% drum strength; the zinc removal rate was 58%, and the metallization rate was 55%.

[0068] Comparative Example 4 (excessive zinc content in low-zinc dust pellets) Unlike Example 1, the zinc content in the low-zinc dust pellets in this comparative example is increased to 5%, while the other conditions are the same as in Example 1.

[0069] The obtained sinter contained 54.8% TFe, 1.8% ZnO, and 55.1% drum strength; the zinc removal rate was 83%, and the metallization rate was 80%.

[0070] The test results of Example 1 and Comparative Example 1 show that if the layered material is not used, and instead the high-zinc dust carbon pellets, low-zinc dust pellets and sintering base are directly mixed and sintered, it is impossible to form a zoned reaction environment where the upper layer is sintered and consolidated and the lower layer is reduced and dezincified. This results in an increase in the ZnO content in the sintered ore, and a significant decrease in drum strength, zinc removal rate and metallization rate.

[0071] The test results of Example 1 and Comparative Example 2 show that if the amount of carbon in the carbon-containing pellets of high zinc dust is too low, the reducing atmosphere in the lower layer is insufficient, and ZnO is difficult to be fully reduced into zinc vapor and discharged with the flue gas, resulting in a significant reduction in zinc removal rate and metallization rate.

[0072] The test results of Example 1 and Comparative Example 3 show that if the zinc content in the carbon pellets in the high zinc dust is too high, the heat required for zinc reduction and the consumption of reducing agent will increase significantly, which will easily cause insufficient reduction reaction in the lower layer and affect the consolidation quality of the upper layer sinter.

[0073] The test results of Example 1 and Comparative Example 4 show that if the zinc content in the low-zinc dust pellets is too high, the zinc residue in the upper sinter will increase, leading to an increase in the ZnO content of the sinter and a decrease in the sinter drum strength.

[0074] Therefore, only by controlling the zinc content of high-zinc dust internally carbonized pellets, the zinc content of low-zinc dust pellets, and the internal carbon content in high-zinc dust internally carbonized pellets within the limits defined in this invention can we simultaneously obtain higher sinter strength, lower sinter ZnO content, higher zinc removal rate, and higher metallization rate.

[0075] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for co-processing zinc-containing dust using layered fabric pre-reduction sintering, characterized in that, Includes the following steps: S1. Material preparation: Prepare high-zinc dust internal carbon pellets, low-zinc dust pellets, and sintering base material respectively; S2. Material distribution: A layered material distribution device is used to distribute high-zinc dust carbon-containing pellets in the lower layer of the sintering trolley to obtain the lower layer material; low-zinc dust pellets and sintering base material are mixed and distributed in the upper layer of the sintering trolley to obtain the upper layer material. S3. Sintering: The upper and lower material layers after the material is fed in the layered feeding device are ignited and sintered from top to bottom to obtain the upper layer of sintered ore and the lower layer of low zinc pre-reduction furnace charge.

2. The method for co-processing zinc-containing dust by pre-reduction sintering of layered fabric according to claim 1, characterized in that, The zinc content of the high-zinc dust with carbon-added pellets is 5-40% of the mass of the high-zinc dust with carbon-added pellets, and the amount of carbon added is 10-20% of the mass of the high-zinc dust with carbon-added pellets. The zinc content of the low-zinc dust pellets is 0.01 to 5% of the mass of the low-zinc dust pellets.

3. The method for co-processing zinc-containing dust by pre-reduction sintering of layered fabric according to claim 1, characterized in that, The alkalinity of the carbon pellets in the high-zinc dust is 0-1; The alkalinity of the low-zinc dust pellets is 0-1; The basicity of the sintering base material is 1.5 to 2.

5.

4. The method for co-processing zinc-containing dust by pre-reduction sintering of layered fabric according to claim 1, characterized in that, In step S2, the mass ratio of low-zinc dust pellets to sintered base material is (0.05~0.3):

1.

5. The method for co-processing zinc-containing dust by pre-reduction sintering of layered fabric according to claim 1, characterized in that, In step S3, the total height of the upper and lower material layers is 300-1000mm, and the height ratio of the upper material layer to the lower material layer is 1:(2-0.1).

6. The method for co-processing zinc-containing dust by pre-reduction sintering of layered fabric according to claim 5, characterized in that, The feed layer also contains fuel, and the fuel content of the feed layer is 2 to 5% of the total mass of the low-zinc dust pellets and sintered base material.

7. The method for co-processing zinc-containing dust by pre-reduction sintering of layered fabric according to claim 5 or 6, characterized in that, The moisture content of the feed layer is 4-12% of the total mass of the low-zinc dust pellets and sintered base material. The moisture content of the feed layer is 4-15% of the mass of the carbon pellets in the high-zinc dust.

8. The method for co-processing zinc-containing dust by pre-reduction sintering of layered fabric according to claim 1, characterized in that, In step S3, the ignition temperature is 1050-1150℃, the ignition time is 60-90s, the sintering negative pressure is 6-20kPa, and the sintering machine speed is 1-4m / min.

9. The method for co-processing zinc-containing dust by pre-reduction sintering of layered fabric according to any one of claims 1-3, characterized in that, The particle size of the carbon pellets in the high-zinc dust is 5-50 mm; The particle size of the low-zinc dust pellets is 6–14 mm.

10. The method for co-processing zinc-containing dust by pre-reduction sintering of layered fabric according to claim 1, characterized in that, The layered fabric distribution device also includes a height sensor and an automatic control system, which are used to adjust the thickness ratio of the upper and lower layers in real time, with the thickness accuracy controlled within ±5mm.

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