Evaluation of trace element availability from secondary metallurgical slag generated in steelmaking by sequential chemical extraction

During carbon steel manufacture, slag residues are generated to remove material impurities from liquid metal and thus control the quality of carbon steel. As the utilization of secondary metallurgical slags is not as effi- cient as those of primary slags, a comprehensive charac- terization of steel ladle slag was performed. Pseudo-total concentrations of a wide range of elements were deter- mined during a 6-week sampling period with relevant physical and chemical properties, sequential extraction of trace elements, and parallel mineralogical characterization of extraction residues from a representative combined sample. According to the results, only Cr and V occurred in elevated concentrations with respective 6-week mean val- ues of 198 and 310 mg kg ^-1 (d.w.). The residual standard deviation of the weekly pseudo-total concentration values of the aforementioned elements (24 and 31 %, respec- tively) indicated that significant variation in the concen- tration of trace elements can occur due to fluctuation in process conditions and/or slag characteristics. The sequential extraction procedure suggested potential phyto- availability of V (123 mg kg ^-1 , d.w., amounting to 41 % of the respective pseudo-total concentration) through, e.g., changes in prevailing redox conditions. Although the analytical approach was validated by the analysis of a certified reference material and the calculation of extrac- tion recoveries, the mineralogical characterization of par- allel extraction residues indicated non-selectivity of the procedure coupled with potential redistribution phenomena during extraction with hydrogen peroxide and ammonium acetate,

Keywords
Certified reference material; Fractionation; Ladle slag; X-ray diffraction