Research On Zinc Removal From Metallurgy Dust Containing Iron

Iron-bearing dust, as a by-product of iron-making, always contains a considerableamount of valuable metals. From the view of environmental protection, dusts should beutilized as the raw material of iron sintering process, but treating improperly willinfluence the quality. Therefore, recycling the dust is becoming more and more important.The current process of dust recycle is sintering, stacking and roasting, but there exists notenough in-depth study, so the objective of this paper is to treat dust by direct reduction.Zinc-removal effects of dust are different in different conditions. Results show that thezinc removal rate can reach as high as95%.Through analysis, the dusts contain carbon as the basis for the reduction. Zinc can beremoved from original dust containing iron by heating to high temperature. At the basisof thermodynamics and kinetics of reduction, the calculation reduction kinetics wasexplored systematically. Pelletized dusts’ property parameters are carbon content, dryingtemperature. The reduction parameters include temperature, reduction time, granularityand thickness of material layer. The pelletizing conditions are for adding10%of water,respectively4%and2%of the binder, without adding carbon, and drying of1h at180℃.Appropriate reduction conditions of dust pellet are temperature of1370K within90minutes, particle size in the range of8~10mm, and zinc removal rate can reach95%.Suitable roasting reduction conditions of coarse dust are temperature of1300K within60minutes, particle size of8~10mm, and zinc removal rate can reach90%.Based on the dynamics theory, in order to enhance utilization rate of iron containingdust and reduce the zinc content, metallurgy principle knowledge is introduced to zincremoval for laboratory study on reduction of the dust pellet and coarse dust, throughvarious stages of analysis, the early and later stages of restrictive factors are CO reaction,interfacial reaction and gas diffusion. Equations are respectivelyln(1f(t))20866.49e150900/RTt,1(1f(t))1/3965.813e117120/RTt,12/3f(t)(1f(t))2/3362.056e93660/RTt. The experimental results show that furtherreducing the temperature and time is benefit to improve zinc removal effect.Figure32; Table9; Reference78...