Strengthen Lead Sulfide Concentrates Sinter Roasting Technology And Mechanism

The sintering of lead sulphide concentrate is one of the most important procedures in lead extraction by pyrometallurgy. The qualities of lead sinter present important effects on the reduction smelting and the recovery of lead.In the paper, focusing on the problems existing the updraught sintering of lead concentrate, such as low bed permeability, low productivity and low qualities of product lead sinter and desulphurization, the enforcing sintering techniques were systematically investigated by using lead concentrate from Zhuzhou metallurgy plant.It was found that the improvement of permeability of the bed, qualities of lead sinter and desulphurization could be achieved by using additive, strengthening granulating, hot blast firing and adjusting the parameters for sintering.For a mixed feed of 65% return, 10% mixed lead concentrate, 7% leaching residue, 4% pyrite residue, 3.8% limestone and 14% Baoshan lead concentrate and 0.5% F-additive, the improvement of desulphurization from 60.86% to 73.37%~76.16%, the reduction of sulphur content in product lead sinter from 2.15% to 1.51%~1.64%, the increase of ISO tumbler index from 49.93% to 54.79%~55.44% and production coefficient from 16.70t/(d.m2) to 18.00 t/(d.m2)~20.00 t/(d.m2) were obtained under conditions of 4.0% moisture of return, 6.8% moisture of blend, 2min blend time, 2min granulating time, 365mm height of sinterbed and 4000Pa updraught pressure.Effective granulation is the formation of granular structure with return as core and concentrate fines as adhering layer. Binders contribute to improvement of surface waterability of returns and fines, and to linkage of fines by adsorbing on surface of fines and returns. High permeability helps to increase oxygen diffusion rate through inner pores, and dolomite acts as additive elevating fluid formation temperature, which results in longer time of desulfurization process. Therefore, desulfurization is enhanced by effective granular structure, high permeability, and dolomite as additive.Mineralogy composition and microstructure of product lead sinterwere studied. It was shown that the strengthening techniques result in increase in cohesion among components in lead sinter and decrease in porosity as well as improvement of microstructure strength. Furthermore, more compounds containing Mg, such as Ca-Fe olivine and Mg-Fe olivine are formed and free CaO and SiO2 are decreased. Therefore, the degradation index of lead sinter is decreased and the qualities are increased remarkably by the strengthening techniques.