Basic Research On Synergistic Reduction And Efficient Separation Of Zinc Dust

Zinc dust produced in the process of iron and steel production is a secondary resource that needs effective development and utilization for iron and steel enterprises.In this thesis,two kinds of zinc-containing dust from blast furnace dust and converter ash are used as raw materials to study the reduction mechanism of two kinds of zinc-containing dust.Based on the types and quantities of binary and multivariate iron-containing minerals in zinc-containing dust,this thesis analyzes the evolution of mineral phases in the reduction process under different systems and clarifies the reaction mechanism of the reduction process.The research results are as follows:（1）When the reduction temperature is 1200°C,the reduction time is 90 min,the FC/O（carbon oxygen ratio）is 2.0,and the ratio of converter dust to blast furnace dust is 7:3,the removal rate of zinc reaches 98.36%,and the metallization degree of iron reaches 90.56%.（2）As an intermediate,（ZnO）_x（Fe O）_1-xplays an important role in the formation of Zn-Fe-C alloys.Part of（ZnO）_x（Fe O）_1-xis obtained by the phase transformation and reduction reaction of Zn_xFe_1-xAl₂O₄to Ca Al₂O₄and Zn_xFe_2-xSiO₄to Ca₂SiO₄,and the other part is from the reduction of Zn_xFe_3-xO₄in zinc-containing dust.The Fe²⁺ions in Fe_xZn_1-xO act as a catalyst to reduce the activation energy required for ZnO reaction,thereby reducing the reduction temperature of ZnO.（3）In the binary ZnO-Fe₂O₃\Fe₃O₄system,the metallization rate and dezincification rate of various reduction product samples increase with the increase of reduction temperature.During the reduction process,Zn Fe₂O₄is first decomposed into ZnO and Fe₂O₃and then reduced.As a limiting step in the reduction process,the formation of Fe_yZn_1-yO phase can effectively promote the reduction of ZnO.（4）In the ternary reduction system of ZnO-CaO-Fe₂O₃,calcium ion Ca²⁺replaces zinc in zinc ferrite,which promotes the separation of zinc and iron.In the ternary reduction system of ZnO-Fe₂O₃-SiO₂,zinc silicate Zn₂SiO₄will gradually change to fayalite Fe₂SiO₄during the reduction process,and the intermediate product fayalite Fe₂SiO₄will be generated from the iron ore Fe O and quartz SiO₂,and then reduced to Fe and molten SiO₂,mainly divided into synthesis and reduction reactions:SiO₂+2Fe O→Fe₂SiO₄and Fe₂SiO₄+C→CO₂+SiO₂.（5）In the quaternary reduction system of ZnO-Fe₂O₃-CaO-SiO₂,the final phase of the sample after reduction is mainly Fe,calcium ferrite and silicate.Some free iron ions are easily combined with CaO to form Fe_xCa_1-xO phase,and the other part of divalent iron ions are combined with free zinc ions to form ZnFeSiO₄.