Zinc-containing dust mud ore blending method based on multi-target comprehensive control of chemical components, soft melting characteristic, balling property and reducibility

Abstract

The invention discloses a zinc-containing dust mud ore blending method based on multi-target comprehensive control of chemical components, soft melting characteristics, balling property and reducibility, which comprises the following steps: S1, carrying out chemical component analysis on a zinc-containing material, and calculating theoretical components of a mixture by combining the output proportion of the zinc-containing material; s2, analyzing the phase equilibrium composition and liquid phase generation thermodynamics of a CaO-SiO2-Al2O3-MgO-FeO-K2O / Na2O multi-element system in combination with the theoretical components of the mixture, and reversely optimizing the mixture ratio to obtain a plurality of groups of reasonable zinc-containing dust mud ore blending schemes; s3, carrying out soft melting performance test on the zinc-containing dust and mud mixture of different ore blending schemes to obtain the deformation temperature DT, the softening starting temperature ST, the hemisphere temperature HT and the flowing temperature FT of the zinc-containing dust and mud mixture; s4, pelletizing under the same condition according to the zinc-containing dust and mud mixtures of different ore blending schemes; s5, carrying out static reduction roasting on the dried zinc-containing dust and mud pellets with different ore blending schemes; and S6, determining an optimized zinc-containing dust mud ore blending scheme by comprehensively considering the chemical components, the softening and melting characteristics, the balling property and the reducibility of the zinc-containing material under the ore blending condition.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical solid waste resource utilization technology, and relates to a zinc-containing dust and sludge blending method based on multi-objective comprehensive control of chemical composition, softening characteristics, pelletizing and reducing properties, and particularly relates to a zinc-containing dust and sludge blending method for controlling the risk of ring formation in rotary kilns or material caking in rotary hearth furnaces. Background Technology

[0002] In the iron and steel metallurgical production process, secondary resources such as zinc-containing dust, blast furnace ash, converter ash, and electrostatic precipitator ash contain volatile harmful elements such as Zn and Pb. If not properly treated, they will not only cause environmental pollution but also lead to a large loss of metal resources. Although the traditional rotary kiln reduction dezincification process is widely used, it is prone to ring formation during the high-temperature treatment of zinc-containing dust. This causes localized hard lumps to form in the kiln body, severely interfering with material movement and thermal regimes, and even leading to kiln lining damage, reduced production capacity, or even furnace shutdown. This has become one of the core bottlenecks restricting the resource utilization of dust.

[0003] Current reduction dezincification processes often rely on empirical ore blending to determine raw material selection. Efficiency and control of rotary kiln ring formation are improved by adjusting dust / sludge ratios, carbon powder content, or heating regimes. However, this approach generally suffers from two key shortcomings: First, the system fails to consider the softening temperature range (ST-HT-FT) of the raw materials and its impact on the formation of low-melting phases. Second, it lacks analysis of the phase stability of the raw materials in the CaO-SiO2-Al2O3-MgO-FeO multi-component system, making it impossible to accurately predict changes in liquid phase formation characteristics and softening properties. This leads to a higher risk of pellet softening, collapse, agglomeration, and aggregation in the high-temperature zone. Furthermore, the particle size structure and composition of dust, sintering ash, and converter ash from different sources vary significantly, resulting in marked differences in their individual ore pelletizing properties (drop strength, compressive strength, bursting temperature, etc.). Traditional mixed ore blending fails to infer contributions based on individual ore properties, often leading to difficulties in pelletizing, loose structure, and high green pellet bursting rates during the pelletizing stage. This further amplifies the risk of ring formation in the subsequent high-temperature zone (e.g., Figure 1 (As shown). Summary of the Invention

[0004] To address the aforementioned issues, this invention constructs a rotary kiln ore blending optimization and ring formation suppression technology path based on "soft melting characteristics, phase evolution, pelletizing performance, and thermal reduction behavior." This method takes a multi-dimensional approach. First, it introduces FactSage thermodynamic software to predict the liquid phase formation range of a multi-component slag system composed of CaO-SiO2-Al2O3-MgO-FeO. By calculating the types of low-melting phases, the amount of liquid phase, and the melting initiation temperature under different blending conditions, it accurately delineates the "low-melting zone risk band," providing a theoretical boundary for the ore blending safety window.

[0005] Secondly, the high-temperature bonding tendency of ash and slag dust is determined by combining the soft melting characteristics test results (ST-HT-FT) to ensure that the liquid phase does not exceed the limit and the molten phase does not aggregate within the reduction temperature range. Then, the particle size distribution, chemical composition and pelletizing behavior (including drop strength, compressive strength and bursting temperature) of secondary raw materials from different sources are combined with the single ore index contribution analysis method to determine the optimal ratio of each raw material in the compound system, so as to achieve the three-in-one pellet performance regulation of "strength matching-structural stability-thermal control".

[0006] Furthermore, at the process implementation level, a seven-step cyclical optimization path—"single ore evaluation, combined proportioning, melt phase prediction, pelletizing experiment, softening verification, ring formation assessment, and reduction test"—is used to construct a comprehensive evaluation system for the entire process of ore blending, pelletizing, drying, and reduction. In the rotary kiln application stage, temperature gradient control and atmosphere zoning adjustment strategies (such as front-stage reduction, mid-stage preheating, and rear-stage cooling) are implemented to further reduce the probability of agglomeration during the reduction process and significantly improve zinc volatilization rate and system stability.

[0007] This invention comprehensively considers the phase diagram characteristics, material softening behavior, and distribution of major chemical components of the CaO-SiO2-Al2O3-MgO-FeO multi-component system. Based on FactSage thermodynamic simulation, it analyzes the liquid phase formation temperature and content to guide raw material proportioning and process design. By enhancing pellet formation through single-ore pelletizing and controlling the reaction path through an internal carbon reduction roasting regime, it achieves efficient dezincification and stable reduction treatment of metallurgical secondary resources such as high-zinc dust, sintering ash, converter ash, and electrostatic precipitator ash, significantly inhibiting ring formation. This method is applicable to industrial applications of typical volatilization reduction equipment such as rotary kilns in steel enterprises, possessing good engineering adaptability and promising prospects for widespread application.

[0008] To effectively suppress ring formation during the rotary kiln treatment of zinc-containing dust and sludge, and to ensure the high-temperature structural stability of the pellets and the efficient removal of harmful elements, this invention provides a zinc-containing dust and sludge blending method based on multi-objective comprehensive control of chemical composition, softening characteristics, pelletizing properties, and reducing properties, comprising:

[0009] S1. Perform chemical composition analysis on zinc-containing materials and calculate the theoretical composition of the mixture based on its output ratio;

[0010] S2. Based on the theoretical composition of the mixture, analyze the phase equilibrium composition and liquid phase generation thermodynamics of the CaO-SiO2-Al2O3-MgO-FeO-K2O / Na2O multi-component system, optimize the mixture ratio in reverse, and obtain several reasonable zinc-containing dust and sludge ore blending schemes.

[0011] S3. For zinc-containing dust and sludge mixtures with different ore blending schemes, conduct softening performance tests to obtain their deformation temperature DT, softening initiation temperature ST, hemispherical temperature HT and flow temperature FT, and establish a systematic softening behavior database to support the scientific formulation of ore blending schemes and the precise control of process windows.

[0012] S4. For zinc-containing dust and sludge mixtures with different ore blending schemes, pelletizing is carried out under the same conditions. The compressive strength, drop strength, anti-bursting performance and drying pulverization rate are systematically evaluated. The pelletizing performance and thermal stability under different material conditions are compared to obtain zinc-containing dust and sludge pellets.

[0013] S5. Static reduction roasting is carried out on zinc-containing dust and sludge pellets with different ore blending schemes after drying to reduce iron oxides to metallic iron.

[0014] S6. Taking into account the chemical composition, softening characteristics, pelletizing properties and reducing properties of zinc-containing materials under the ore blending conditions, determine the optimized zinc-containing dust and sludge blending scheme.

[0015] In a preferred embodiment, in step S1, the zinc-containing material includes one or more of the following: zinc-containing dust and sludge mixed ore, return material, bag filter ash, electrostatic precipitator ash, blast furnace ash, and steelmaking ash from iron and steel metallurgical enterprises.

[0016] The chemical composition analysis of zinc-containing materials includes, but is not limited to, total iron content, FeO, CaO, SiO2, Al2O3, MgO, K2O, Na2O, Zn, Pb, carbon content, and loss on ignition. Combined with the production ratio of zinc-containing materials, the theoretical composition of the mixture is calculated.

[0017] In the preferred embodiment, in step S2, during phase diagram analysis, the phase equilibrium thermodynamics of the CaO-SiO2-Al2O3-MgO-FeO-K2O / Na2O multi-component system at 1000~1250℃ and under different atmospheres (air, CO atmosphere) is analyzed using FactSage software. The multi-component phase diagram of the main components is drawn, and based on the chemical composition of the mixture, the phase equilibrium zone it is in and the liquid phase generation range and main mineral phase transformation path that it may experience during the heating process are determined. It is judged whether it forms a structural environment that is conducive to improving the softening performance and dezincification efficiency, and then the raw material ratio is adjusted in reverse to avoid the risk of rotary kiln ring formation caused by the low temperature and low viscosity liquid phase generation.

[0018] In the preferred scheme, in step S3, the carbon content of the zinc-containing dust and sludge mixture is controlled to be 10%~25% by its own carbon content and added carbon. The deformation temperature DT (the tip of the ash cone begins to round or bend), softening initiation temperature ST (the height of the ash cone drops to 1 / 2 of its original height), hemispherical temperature HT (the ash cone melts into a hemispherical shape, with height ≈ width) and flow temperature FT (the ash cone completely melts and spreads into a thin layer) are obtained. The risk level of ring formation is comprehensively evaluated to achieve full-process control of the structure-behavior-performance of the ore blending scheme.

[0019] In the preferred embodiment, in step S3, based on the establishment of a database of the system's softening behavior, a reverse model is constructed to evaluate the contribution of each raw material to the overall performance of the mixed pellets; a multi-objective optimization method is adopted to achieve coordinated matching of pelletizing properties, thermal stability, and softening window, so as to avoid problems such as local liquid phase enrichment and early structural collapse caused by mismatch of softening intervals between raw materials.

[0020] During model optimization, recycled materials or sludge with both thermal stability and structural strengthening capabilities are prioritized as the main material, supplemented by conditioning raw materials with good pelletizing properties and a high melting point tendency (such as high-Al and high-Mg materials) to achieve a synergistic improvement in structural homogenization and anti-ringing ability. The final formulation ensures controlled liquid phase formation while possessing high pelletizing rate, strength, and thermal structural integrity, providing a material guarantee for the high-temperature reduction stability of the internally formulated carbon pellets.

[0021] In the preferred embodiment, during step S4, the binder used in the pelletizing process is bentonite or bentonite-based composite binder, with a binder dosage of 1.0% to 3.0% and a moisture content of 15% to 20%.

[0022] In the preferred embodiment, in step S4, the green pellets are dried and dehydrated at 200~350℃ and wind speed of 0.6~1.0m / s to reduce the moisture content to less than 1% and the compressive strength of the dried pellets to greater than 200N / P.

[0023] In the preferred embodiment, in step S5, the reduction temperature is 1100~1200℃, the reduction time is 20~90min, the removal rate of Zn and Pb is not less than 90%, and the metallization rate of Fe is stably above 70%, and the mass fraction of +10mm pellets is higher than 80%.

[0024] In the preferred embodiment, in step S5, the liquid phase content is controlled to be below 15% to prevent excessive liquid phase formation and reduce the risk of ring formation in the rotary kiln or material caking in the rotary hearth furnace.

[0025] The zinc-containing dust and sludge blending method described in this invention can be applied to reduction dezincification processes in coal-based rotary kilns, rotary hearth furnaces, etc., and has broad industrial adaptability and resource integration potential.

[0026] This invention aims to provide an optimized ore blending method for zinc-containing dust and sludge based on chemical composition analysis, phase diagram technology, softening properties, and the regulation of single-ore pelletizing and reduction roasting behavior. This method addresses the ring formation problem in rotary kiln processing, achieving efficient removal of harmful elements, efficient recovery of iron resources, and structural stability of pellets during high-temperature processing. Existing rotary kiln methods for treating zinc-containing dust and sludge largely rely on empirical ore blending, lacking the ability to calculate the content of major components using phase diagrams, identify the low-melting-point eutectic formation range, and employ a systematic design driven by quantitative softening data and raw material property data. This makes it difficult to control the formation of low-melting phases and the risk of ring formation from the source. This invention establishes a raw material softening property database, introduces single-ore pelletizing performance to back-calculate ore blending, and optimizes the internal carbon reduction process, forming a quantifiable control system for the entire process of ore blending, pelletizing, drying, and roasting.

[0027] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0028] (1) Suppress ring formation from the source: Based on the "soft melting database-driven ore blending and classification + multi-element phase diagram analysis", the formation of low melting phase is accurately predicted. By controlling the amount of liquid phase and the soft melting window of the CaO-SiO2-Al2O3-MgO-FeO system, the agglomeration tendency of pellets in the 1100~1250℃ reduction zone is effectively weakened, the ring strength and occurrence frequency of rotary kiln are significantly reduced, and the continuous operation cycle is significantly extended.

[0029] (2) Balancing efficient removal of Zn and Pb with high metallization rate of Fe to improve resource utilization efficiency: By using "internal carbon sequential reduction + drying and roasting integrated control", the best synergy between Zn and Pb volatilization and Fe phase reduction is achieved. The pellets can quickly cross the FeO phase stable zone, promote the generation of metallic iron, and maintain the compactness and strength of the pellet structure.

[0030] (3) Achieving parameterization, replicability, and iterative optimization of ore blending schemes: By "back-engineering of single-ore pelletizing performance + coupled evaluation of multiple indicators of softening and thermal stability", a quantifiable contribution model is constructed, so that ore blending no longer depends on manual experience. This technical route has the characteristics of database and parameterization, and can be quickly adapted and automatically iterated according to the dust and sludge composition of different steel plants, thereby improving the reliability and promotion value of industrial applications. Attached Figure Description

[0031] Figure 1 A schematic diagram illustrating the traditional treatment path and existing problems of zinc-containing dust and sludge;

[0032] Figure 2 The diagram shows the quaternary phase system of CaO-SiO2-Al2O3-5wt% MgO (red dots represent the initial composition, and other marked dots represent the liquid phase composition after optimizing the mixture composition).

[0033] Figure 3 The effect of binary basicity (CaO / SiO2) on the theoretical liquid phase formation amount of the CaO-SiO2-Al2O3-MgO quaternary system;

[0034] Figure 4 The effect of FeO content on the liquid phase formation of the CaO-SiO2-Al2O3 ternary system;

[0035] (a-5% FeO; b-10% FeO; c-15% FeO; d-20% FeO; e-25% FeO; f-30% FeO)

[0036] Figure 5 The effect of FeO content on the theoretical liquid phase formation amount of the CaO-SiO2-Al2O3-MgO quaternary system;

[0037] Figure 6 The effect of Na2O content on the liquid phase formation of the CaO-SiO2-FeO ternary system;

[0038] Figure 7 This is a test diagram of the softening and melting properties of zinc-containing materials;

[0039] Figure 8 This is a schematic diagram illustrating the optimized zinc-containing dust and sludge treatment path and its advantages according to the present invention. Detailed Implementation

[0040] The present invention will be described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited to the following embodiments;

[0041] The present invention will be further described below with reference to specific embodiments and accompanying drawings:

[0042] Example 1

[0043] A method for blending zinc-containing dust and sludge based on multi-objective comprehensive control of chemical composition, softening properties, pelletizing properties, and reducibility includes the following steps:

[0044] S1. A zinc-containing dust and sludge mixture, return material, blast furnace ash, and steelmaking ash from a steel plant were selected as raw materials. The chemical composition of the zinc-containing materials was analyzed. The total iron content, FeO, CaO, SiO2, Al2O3, MgO, K2O, Na2O, Zn, Pb, carbon content, and loss on ignition of each raw material were analyzed. The theoretical composition of the mixture was calculated based on its production ratio, as shown in Table 1. The theoretical carbon content of the mixture is approximately 20%.

[0045] Table 1 Theoretical composition of the mixture / wt%

[0046]

[0047] S2. Based on the theoretical composition of the mixture, during phase diagram analysis, the phase equilibrium thermodynamics of the CaO-SiO2-Al2O3-MgO-FeO-K2O / Na2O multi-component system at 1000~1250℃ and under different atmospheres is analyzed using FactSage software. Multi-component phase diagrams of the main components are drawn, and the phase equilibrium zone in which the mixture is located and the liquid phase generation range and main mineral phase transformation path that may be experienced during the heating process are determined according to the chemical composition of the mixture.

[0048] For the CaO-SiO2-Al2O3-MgO quaternary system, the total content of the four components in Table 1, converted to 100%, is 46.25%, 35.97%, 12.46%, and 5.32%, respectively, with a binary basicity of 1.3; combined with the phase diagram of the CaO-SiO2-Al2O3-5wt% MgO quaternary system (… Figure 2 It can be seen that the initial liquid phase composition is close to the low melting point liquid phase region. Increasing the binary basicity (CaO / SiO2) will help increase the liquid phase formation temperature, which is beneficial for suppressing ring formation in the rotary kiln. According to Figure 3 The effect of alkalinity on the theoretical amount of liquid phase formation is shown. A suitable CaO / SiO2 ratio is recommended to be no less than 1.5, because the FeO and alkali metal (K2O+Na2O) components in the mixture both promote liquid phase formation. Figures 4-6 As shown, the alkali metal content in the mixture should be controlled to be as low as 2%, and the high-temperature rapid reduction of FeO should be ensured under thermal conditions to reduce the stable liquid phase region.

[0049] Three ore blending schemes (AC) were thus formulated, as shown in Table 2.

[0050] Table 2. Baseline and 3 Optimization Schemes

[0051]

[0052] S3. By controlling the carbon content of the zinc-containing dust and sludge mixture to 20% through its own carbon content and added carbon, and referring to GB / T 219 or ASTM D1857 coal ash cone softening performance test method, obtain its deformation temperature DT (the tip of the ash cone begins to round or bend), softening initiation temperature ST (the height of the ash cone drops to 1 / 2 of its original height), hemispherical temperature HT (the ash cone melts into a hemispherical shape, height ≈ width), and flow temperature FT (the ash cone completely melts and spreads into a thin layer). Comprehensively assess the ring formation risk level to achieve full-process control of the structure-behavior-performance of the ore blending scheme. Establish a systematic softening behavior database to support the scientific formulation of ore blending schemes and precise control of process windows, such as... Figure 7 As shown;

[0053] Based on the establishment of a database of softening behavior, a reverse model is constructed to evaluate the contribution of each raw material to the overall performance of the mixed pellets. A multi-objective optimization method is adopted to achieve coordinated matching of pelletizing properties, thermal stability and softening window, so as to avoid problems such as local liquid phase enrichment and early structural collapse caused by mismatch of softening intervals between raw materials.

[0054] Table 3. Softening properties of mixtures with different ore blending schemes

[0055]

[0056] S4. For zinc-containing dust and sludge mixtures with different ore blending schemes, pelletizing was carried out under the same conditions. During the pelletizing process, bentonite (1.2% dosage) was used as the binder, and the moisture content was 18%. The green pellets were dried and dehydrated at 300℃ and an air velocity of 0.8m / s to reduce the moisture content to below 1%, and the compressive strength of the dried pellets was greater than 200N / P. The compressive strength, drop strength, anti-burst performance, and drying pulverization rate were systematically evaluated. The pelletizing performance and thermal stability under different material conditions were compared. Some implementation examples are shown in Table 4. The results show that all proportions can produce qualified green pellets, but the compressive strength of the dry pellets in Scheme C is greater than 200N / P, which helps to reduce the pulverization rate after entering the kiln.

[0057] Table 4. Pelletizing performance of different ore blending schemes

[0058]

[0059] S5. Static reduction roasting was performed on zinc-containing dust pellets with different pre-dried ore blending schemes. The reduction temperature was 1150℃, and the reduction time was 75 min. The removal rates of Zn and Pb were not less than 90%, while the metallization rate of Fe was stably above 70%, and the mass fraction of +10mm pellets was above 80%. The liquid phase content was controlled to be below 15% to prevent excessive liquid phase formation. The results are shown in Table 5. Compared with the baseline scheme, schemes A and C with adjusted compositions all achieved good indicators, but scheme C was better.

[0060] Table 5. Reduction and dezincification effects of zinc-containing pellets under different ore blending schemes

[0061]

[0062] S6. Taking into account the chemical composition, softening properties, pelletizing properties, and reducibility of zinc-containing dust and sludge, the optimized ore blending scheme for zinc-containing dust and sludge is determined as follows: 43.8% zinc-containing dust and sludge blended ore, 19.5% blast furnace ash, 29.3% steelmaking ash, and 4.9% recycled material, with the addition of 1% carbide slag and 1.5% high-magnesium powder, so that the binary basicity (CaO / SiO2) of the pellets reaches 1.5, the MgO / SiO2 mass ratio is ≥0.45, and the alkali metal (K2O+Na2O) content is <2.0%.

[0063] Therefore, this invention provides a ore blending method that comprehensively considers the softening properties of raw materials, single-ore pelletizing behavior, thermal stability, and dezincification efficiency. It clarifies the low-melting phase formation behavior of the multi-component system through FactSage thermodynamic calculations, and combines softening characteristic testing with single-ore pelletizing performance. This allows for controllable regulation of the entire process from raw material classification and proportioning design to pelletizing-drying-reduction. It achieves a multi-coupled regulatory effect, reducing low-melting phases at the source, blocking liquid phase aggregation during the process, and improving the thermal stability of the pellets through structural enhancement. This effectively suppresses the risk of ring formation in rotary kilns, improves dezincification efficiency and production line continuity, and provides an engineered and highly adaptable ore blending solution for the resource utilization of steel dust and sludge. Figure 8 As shown.

[0064] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for blending zinc-bearing dust and sludge based on multi-objective comprehensive control of chemical composition, softening properties, pelletizing properties, and reducing properties, characterized in that: include: S1. Perform chemical composition analysis on zinc-containing materials and calculate the theoretical composition of the mixture based on its output ratio; S2. Based on the theoretical composition of the mixture, analyze the phase equilibrium composition and liquid phase generation thermodynamics of the CaO-SiO2-Al2O3-MgO-FeO-K2O / Na2O multi-component system, optimize the mixture ratio in reverse, and obtain several reasonable zinc-containing dust and sludge ore blending schemes. S3. For zinc-containing dust and sludge mixtures with different ore blending schemes, conduct softening performance tests to obtain their deformation temperature DT, softening initiation temperature ST, hemispherical temperature HT and flow temperature FT, and establish a systematic softening behavior database to support the scientific formulation of ore blending schemes and the precise control of process windows. S4. For zinc-containing dust and sludge mixtures with different ore blending schemes, pelletizing is carried out under the same conditions. The compressive strength, drop strength, anti-bursting performance and drying pulverization rate are systematically evaluated. The pelletizing performance and thermal stability under different material conditions are compared. After drying and dehydration treatment, dried zinc-containing dust and sludge pellets are obtained. S5. For zinc-containing dust and sludge pellets with different ore blending schemes, static reduction roasting is carried out to reduce iron oxides to metallic iron. S6. Taking into account the chemical composition, softening characteristics, pelletizing properties and reducing properties of zinc-containing materials under the ore blending conditions, determine the optimized zinc-containing dust and sludge blending scheme.

2. The method according to claim 1, characterized in that, In step S1, the zinc-containing material includes one or more of the following: zinc-containing dust and sludge mixed ore, return material, bag filter ash, electrostatic precipitator ash, blast furnace ash, and steelmaking ash; The chemical composition analysis of zinc-containing materials includes, but is not limited to, total iron content, FeO, CaO, SiO2, Al2O3, MgO, K2O, Na2O, Zn, Pb, carbon content, and loss on ignition. Combined with the production ratio of zinc-containing materials, the theoretical composition of the mixture is calculated.

3. The method according to claim 1, characterized in that, In step S2, during phase diagram analysis, the phase equilibrium thermodynamics of the CaO-SiO2-Al2O3-MgO-FeO-K2O / Na2O multi-component system at 1000~1250℃ and under different atmospheres is analyzed using FactSage software. The multi-component phase diagram of the main components is drawn, and based on the chemical composition of the mixture, the phase equilibrium zone it is in, the liquid phase generation range it may experience during the heating process, and the main mineral phase transformation path are determined. It is judged whether a structural environment conducive to improving softening performance and dezincification efficiency is formed. Then, the raw material ratio is adjusted in reverse to avoid the risk of rotary kiln ring formation caused by the formation of low-temperature, low-viscosity liquid phase.

4. The method according to claim 1, characterized in that, In step S3, the carbon content of the zinc-containing dust and sludge mixture is controlled to be 10%~25% by its own carbon content and added carbon, and its deformation temperature DT, softening initiation temperature ST, hemispherical temperature HT and flow temperature FT are obtained to comprehensively assess the risk level of ring formation.

5. The method according to claim 1, characterized in that, In step S4, during the pelletizing process, bentonite or bentonite-based composite binder is used as the binder, with a binder dosage of 1.0% to 3.0% and a moisture content of 15% to 20%.

6. The method according to claim 1, characterized in that, In step S4, the green pellets are dried and dehydrated at 200~350℃ and wind speed of 0.6~1.0m / s to reduce the moisture content to less than 1% and the compressive strength of the dried pellets to be greater than 200N / P.

7. The method according to claim 1, characterized in that, In step S5, the reduction temperature is 1100~1200℃, the reduction time is 20~90min, the removal rate of Zn and Pb is not less than 90%, and the metallization rate of Fe is stably above 70%, and the mass fraction of +10mm pellets is above 80%; the liquid phase content is controlled to be below 15% to prevent excessive liquid phase generation and reduce the risk of ring formation in rotary kiln or material caking in rotary hearth furnace.

8. The application of the method according to any one of claims 1 to 7, characterized in that, It is applied to reduction dezincification processes such as coal-based rotary kilns and rotary hearth furnaces.

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