Study On The Process And Mechanism Of Recovering Valuable Components From Lead Smelting Water Quench Slag

Lead slag mainly refers to the waste slag produced in the process of pyrometallurgical lead production,including blast furnace slag and fuming furnace waste slag.With weathering and rainfall,the toxic elements in lead slag may seep into the soil and groundwater and cause environmental pollution.Lead slag contains a lot of valuable metals such as lead,zinc,copper,silver and iron,which can be reused as secondary resources.For this reason,the resource utilization and harmless treatment of lead smelting waste residue is the only way for the sustainable development of lead and zinc industry in the future.Because lead slag is a complex system,a single technology can not solve all the problems.Therefore,the metal recovery technology should be combined according to the physical and chemical properties of all kinds of lead slag.In this paper,taking the lead smelting water quenching slag produced by a smelter in Baiyin as the research object,the new process of direct reduction roasting-flotationmagnetic separation is used to recover valuable elements such as copper,iron,zinc and so on.Through direct reduction roasting,zinc in the water-quenched slag is volatilized in the form of metal vapor and separated from other components,iron is reduced to metal iron and recovered by magnetic separation,and some copper and metal iron form copper-iron alloy to be recovered by magnetic separation.The other part of copper is recovered by flotation.The whole process open circuit test can obtain an iron concentrate with a zinc volatilization rate of 99.36%,an iron grade of 92.64% and a recovery of 91.33%.The grade and recovery of copper in the iron concentrate are 1.83% and 29.54%,respectively.The copper grade is 20.07% and the copper recovery is 34.20%.The copper concentrate with a copper grade of 18.24% and a copper recovery of 56.22% can be obtained by closed-circuit test;the iron grade of 92.85%,the iron recovery of 90.79%,the copper grade of 1.92% and the copper recovery of 33.76% can be obtained from the copper flotation tailings by magnetic separation.The comprehensive recovery of copper is 89.98%.Through the thermodynamic analysis of minerals by thermodynamic reaction equation,the behavior changes of minerals under different roasting conditions were analyzed by X-ray diffraction(XRD)and scanning electron microscope(SEM),the phase change law of water-quenched slag minerals was revealed,and the automatic analysis system of mineral dissociation degree(MLA)was used to study the process mineralogy of copper-bearing minerals before and after roasting.The results show that the volatilization of zinc in water-quenched slag is mainly affected by temperature.In metallic iron,some Cu elements overlap with Fe elements,showing a close symbiotic relationship.This part of the metal iron is a copper-iron alloy containing some copper,so the recovery rate of copper in the iron concentrate is about 34%.When the target grade of chalcopyrite is reached after roasting,the theoretical recovery rate of chalcopyrite is 22.05% higher than that before roasting.