Optimization Of Utilization Rate Of Iron And Zinc In The Process Of Materialization Of Zinc-bearing Dust

Grouping materialization of Fe and Zn in zinc dust by wet chemical methods has the advantages of short process and sustainable resources.It is a promising research direction in the field of high value-added utilization of zinc-bearing dust and sludge.However,up to now,there are few systematic studies on the optimization of leaching rate of Fe and Zn aimed at their simultaneous leaching for high zinc-bearing dust.This paper is divided into two parts to carry out research work.Firstly,the site investigation on the types,annual output,composition characteristics and comprehensive utilization of zinc dust in Ma Steel Company is carried out,providing reliable data and information for the high value-added use of zinc-bearing dust.Secondly,the suitable types of zinc-bearing dust are determined based on the design of grouping materialization of Fe and Zn in zinc-bearing dust,and the optimum parameters of the dust pretreatment and acid hydrolysis process are obtained through systematic experimental studies on the optimization of the leaching rate of Fe and Zn in the acid hydrolysis process.The results show that the zinc-bearing dust and sludge generated from the process of iron and steel metallurgy of Ma Steel Company mainly includes blast furnace dust?BF dust?,electric arc furnace dust?EAF dust?,blast furnace gas sludge,converter OG sludge and phosphate sludge in steel metallurgical production.The total annual production of zinc-bearing dust is more than 350,000 tons.At present,the rotary hearth furnace and rotary kiln process are the main methods for the comprehensive utilization of zinc-bearing dust in Ma Steel Company.Their capacity to treat zinc-bearing dust reaches 400,000 tons/a,and the comprehensive utilization rate of zinc-bearing dust lies in top of the industry.In order to increase the added value of comprehensive utilization of zinc-bearing dust and establish a new model for efficiently reusing zinc-bearing dust in a large-volume and multi-channel route,the enterprise has an urgent need for the technology of recycling zinc-bearing dust in high added value.Among all kinds of zinc-bearing dust,the content of Fe and Zn in BF dust and EAF dust is relatively high.Their highest contents of Fe₂O₃ and ZnO can reach 33.57%,10.06%and 67.33%,16.83%,respectively.They have high resource endowments and significant materialization values,and are suitable objects for grouping materialization of Fe and Zn in the solid wastes.The acid leaching rate of Fe and Zn in the EAF dust was experimentally studied and optimized.Analysis results of XRF,XRD and XPS show that the mass percentages of Fe and Zn?measured by their respective oxides?in the EAF dust are67.33%and 16.83%,respectively.Its phase is dominated by spinel phase?ZnFe₂O₄,Fe₃O₄?and hematite phase?Fe₂O₃?.Zn mainly present as ZnFe₂O₄ and ZnO phases.Fe mainly present as Fe₃O₄,Fe₂O₃ and ZnFe₂O₄,and Fe²⁺and Fe³⁺coexist in the EAF dust.The orthogonal test method is used to investigate the effects of the factors of dust calcination temperature,acid hydrolysis temperature and acid hydrolysis time on the leaching rate of iron and zinc.Optimal process parameters are obtained by evaluating the significance of each factor through range analysis and variance analysis of the orthogonal test results.The experimental results are summarized as follows.For the leaching rate of iron ion,the significance order of the three factors is acidolysis temperature>calcination temperature>acidolysis time.For the leaching rate of zinc ion,the significance order of the three factors is acidolysis temperature>acidolysis time>calcination temperature.The optimum solution is determined as:calcination temperature 450°C,acidolysis temperature 90°C,acid leaching time 8 h.The leaching rates of Fe and Zn based on this scheme are 99.77%and 97.27%,respectively.Taking BF dust as the research object,the effects of reduction roasting and acid hydrolysis on the leaching rate of Fe and Zn in BF dust are investigated,and the process parameters are optimized.Analysis results of XRF and XRD show that the proportion of iron and zinc?measured by their respective oxides?in the BF dust used in the experiment was 43.5%and 22.12%?mass%?,respectively.Fe mainly exists in the phase of Fe₂O₃,ZnFe₂O₄ and Fe₃O₄,and Zn mainly exists in the form of ZnFe₂O₄and ZnO.The effects of calcination temperature,acidolysis temperature and acidolysis time are investigated by orthogonal test method with the leaching rate of iron and zinc as evaluating indicator.The experimental results are summarized as follows.Taking into overall consideration on leaching rate of Fe and Zn,the significant order of the three factors is:acidolysis temperature>calcination temperature>acidolysis time.The optimal solution is ascertained as follows:calcination temperature 650°C,acidolysis temperature 90°C,acidolysis time 4 h.The leaching rates Fe and Zn of this scheme are 95.92%and 95.34%,respectively.