Quantitative Zn speciation in zinc-containing steelmaking wastes by X-ray absorption spectroscopy

摘要

To prevent improper handling of zinc-containing steelmaking wastes and find better solutions for recycling these materials, synchrotron induced X-ray absorption spectroscopy (XAS) was used to determine the chemical form of zinc quantitatively at the atomic scale. Five types of zinc-containing steelmaking wastes generated during the production of carbon steel in blast furnace, basic oxygen furnace and blast furnace were collected. In dust collected from the gas-cleaning system of electric arc furnace (EAFD) and basic oxygen furnace developed by Lurgi and Thyssen companies (BOF LT), zinc existed predominantly as franklinite phase (ZnFe_2O_4). The presence of Zn-O, Zn-Fe, Zn-Zn bonds in the nearest two coordination shells were observed. In off gas sludge generated in basic oxygen furnace (BOF OG), three main types of zinc species were identified: Zn_5(CO_3)_2(OH)_6, ZnFe_2O_4 and ZnSO_4·7H_2O. Zn-O and Zn-Zn bonds occurred in the nearest two coordination shells. Blast furnace dust (BFD) comprised about 39% soluble phase in the form of ZnCl_2 and 61% insoluble phase in the form of ZnFe_2O_4. In blast furnace sludge (BFS), ZnCl_2 was also obtained as the soluble phase and the insoluble phase was zinc silicate possibly in the form of ZnSiO_3. These findings deepened our understanding of zinc speciation contained in zinc-containing steelmaking wastes and provided the fundamental information for better dealing with this kind of metallurgical residues.