Reaserch On Extracting Zn From Dust Dried In BF By Vacuum Carbothermic Reduction

Zinc is a trace element in BF, which mainly exists in the oxide and sulfide form. Thecycle of zinc in BF is mainly the small circulation in BF and the large circulation betweensintering and BF. When the Zinc quantity in BF is higher, it can do harm to BF output andreduce the quality of molten iron. Besides, it can reduce the service life of BF. Nano zincoxide is a kind of multi-functional inorganic material. Compared with the traditional ZincOxide, nano Zinc Oxide has larger specific surface area and higher chemical activity.Recently, it has shown many special function in catalysis, optical, magnetism, mechanicsand so on.Using BF dust of Zhongtian Iron and Steel Planta as raw material, Zinc was recoveredby vacuum carbothermic reduction, and the reduction residues in which Fe and C wereenriched could be recycled as the raw materials for ironmaking. The influence of themorphologies of the product is investigated with EDS、SEM and XRD detection means.The kinetics of Zn reducing from pellet made of dust dried in BF by vacuum carbothermicreduction was approached using the shrinking unreacted core model and theory of diffusion.The influences of pressure of system, pellet diameter and reaction temperature on thereduction ratio of Zn were investigated in detail. Finally, the processes and conditions forpreparation of nano-Zinc oxide by washing, vacuum distillation, liguation and vacuumoxidation were researched.The results show that the Zinc reduction rate is93.19%at1173K and1KPa for45min by vacuum carbothermic reduction. The apparent activation energy of the carbongasification or that of interface reaction is small by contrast with that of the gas diffusion ofZinc vapor and CO which can be demonstrated that the carbon gasification or interfacereaction has a lesser effect, but the gas diffusion of Zn vapor and CO has a very importanteffect on the reduction reaction. The internal diffusion is the rate limiting step of overall Znreduction. The apparent reaction progression is1, and the apparent activation energy iscalculated to be172.39kJ/mol within the selected temperature range from1023K to1173K.KCl and NaCl in the condensation can be removed by washing. Zn, Pb, Cu, Al andsome other impurities are separated by vacuum distillation. C in the condensation isremoved by liguation and the spelter is recovered. Using spelter as raw material, nano-zincoxide is prepared by vacuum oxidation, and the purity of nano-zinc oxide exceeds99.8%.The nano-zinc oxide has a hexagonal wurtzite structure, almost uniform needle shape, and the high ratio of length to diameter. The whole process of Zn recovery rate is up to81.43%.