Research On Smelting Desulfurization Of Lead And Zinc Mixed Concentrate By Oxygen Injection

With the rapid development of lead and zinc industry in our country,there are fewer and fewer high-grade lead-zinc mines in our country and more attention has been paid to the utilization of refractory lead and zinc mixed concentrates.However,it is difficult for the present beneficiation process to separate the lead and zinc mixed concentrate into a single lead concentrate and zinc concentrate.Moreover,the ISP(Imperial Smelting Process)method that can deal with the lead and zinc mixed concentrate directly has the technical problems of high energy consumption and large environmental pollution.In order to achieve the cleaning smelting of lead and zinc mixed concentrate,a new method of cleaning metallurgy for oxygen injection smelting oxidation desulfurization of lead-zinc mixed sulfide concentrate-C/CO injection to reduct the slag was proposed by our group and Enfi Corporation.In this paper,The basic scientific problems of the smelting desulfurization process of lead and zinc mixed concentrate by oxygen injection were studied.Firstly,the feasibility of this method is confirmed by analyzing the dirgrams of predominant area.The distribution law of the main metals in phases and thermodynamic properties of the smelting system were calculated by FactSage Equilibrium,the phase diagrams of the smelting desulfurization slag system was also calculated by FactSage Phase Dirgram.It provides a theoretical basis for the smelting oxidation desulfurization experiment.Secondly,the single-factor experiment was designed to study the process of smelting desulfurization of lead and zinc mixed concentrate by oxygen injection systematically.The results showed that the maximum sulfur content in the slag was only 0485%,which is lower than the industrial smelting requirements.The XRD patterns showed that the main pahses in the air-cooled slag was Zn2SiO4 and ZnFe2O4.There were PbS,Pb and Fe3O4 phases detected in XRD patterns of air-cooled slag,when temperature is low,oxygen lance heght is high,oxygen flow rate is low and reaction time is short.Also,the law of the volatilization rate of lead and zinc was studied.The results indicated that the temperature was the dominant factor to the volatilization rate of lead.Molten slag can reduce the volatilization rate of zinc significantly.The volatilization of lead and zinc were in the form of sulfide mainly.The sulfides were oxided to the sulfate at low temperature.Thirdly,the law of the enrichment rate of copper in the form of lead matte was studied.The results illustrated that oxygen partial pressure of system was the dominant factor to the enrichment rate of copper.The high enrichment rate of copper and the low sulfur content in slag can be achived simultaneously under some conditions.When temperature was 1523 K,Fe/SiO2 was 0.5,CaO/SiO2 was 0.6,oxygen flow rate was 80 L/h,oxygen lance height was 3.0 cm and reaction time was 30 min,the enrichment rate of copper can be reached to 46.98%,the sulfur content in slag was only 0.145%.Finally,through the research on the law of volatilization of lead and zinc in the process of smelting desulfurization of lead and zinc mixed concentrate,A new method of separation of PbS with vacuum distillation in lead and zinc mixed concentrate was proposed.The feasibility of it was studied.The results of vaccum distillation showed that the volatilization rate of lead and zinc were 87.72%and 1.41%,respectively,when temperature was 1423 K,distillation time was 1.0 h.The zinc and iron sulfides in residues occurred to reconstruct the mineral phases Zn0.825Fe0.175S and Zn0.721Fe0.279S which has good crystallinity.