| Blast furnace dust as one of the major solid waste which is produced by iron andsteel enterprises as main components are iron and carbon, at the same time it includesa few elements as silicon, aluminum, calcium, magnesium and so on. In addition to itcontains harmful elements such as zinc, lead and alkali mental. Most domestic plantshave not effectively used Blast furnace dust, which generally used by returningsintering plant as mixture of sinters in the past. But the easy volatilization elements asZn in Blast furnace dust will recycle and concentrate in Blast furnace, resulting inupper of Blast furnace heeling, gas pipe blocking, therefor Blast furnace cannotnormally operate. Minority palnts obtain secondary dusts containing Zn and chargecontaining Fe by separation or hydrometallurgy process. But the technologicalprocess is long and the process scale is small with extremely low recovery rate.Therefore, it was of great significance to the recycling use of secongdly metallurgicalresources that investigating the green environmental protection technology, whichcould recover the iron, carbon and valuable metals effectively in blast furnace andreduce the environmental pollution.Firstly, Factsage thermodynamic software is adopted to calculated the reductionprocess of zinc oxide,which set the atmosphere as the air and the carton content(nc:nZnO) of1:1,1:1.5,1:2. Calculation results show that of zinc oxide reduction can bedivided into four stages under the air condition: carbon oxidation, carbon gasificationreaction, ZnO+C=Zn+CO and CO+ZnO=Zn+CO2.Also, zinc oxide can be restored onthe condition of temperature higher than1000℃and nc:nZnO=1:1.5. Under laboratory conditions, using simultaneous thermal analyzer and with thepure Fe2O3,ZnO and graphite as raw material, the reduction process of maincomposition on the blast furnace dust are simulation and the reaction machanism areanalyzed. Results show that the C reduction ZnO and Fe2O3at the same time, thecorresponding maximum reaction temperature is1122.8℃,which is between1200.4℃and1106.2℃in the separate reductio of ZnO and Fe2O3; also, when the content ofZnO increases by10%, beginning temperature and the maximum reaction rate of thecorresponding temperature would lag about20℃, reason about the lag is that thespinel solid solution ZnFe2O4which is generated in early stage of the reaction hinderthe reaction.also, lattice of ZnFe2O4is stable and Fe and zinc element is difficult to berestored, which cause that ZnO and Fe2O3produces mutual inhibition in the reductionprocess.On the basis of analysis the physical and chemical performance, using theequilipments such as resistance furnance and XRD, the high temperature reductionfurnace are conducted after pelletizing of blast furnace dust from some steel plant.reduction roasting experiments of pellets containing carbon is conducted with additionof converter dust slime in blast furnace dust to study the impact of reductiontemperature, atmosphere, time and the C/O on dezincification rate and metallizationrate of pellets. Results show that reduction effect is very satisfactory when carbon inblast furnace dust is used as reductant. Dezincing rate more than95%andmetallization rate more than85%can be obtained under the best reduction roastingtechnological conditions： pellet C/O is1.1, reduction temperature at1250℃,reduction time is40min.The effect of the atmosphere on the dust has little difference,and the reduction effect of air condition slightly below the one of N2and O2atmosphere. |
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