Separation of valuable elements from steel making slag by chlorination

•Fe, Ti and a part of Mg were volatilized by chlorination of slag at 1000 °C for 60 mn.•Remarkable volatilization of Fe, Ti and P was observed during carbo-chlorination.•Selective separation of P was possible by carbo-chlorination of chlorination-residue.•Fe, Ti, and P can be separated by combination of chlorination and carbo-chlorination. Herein, we investigated the volatilization behavior of slag elements during chlorination of converter slag and Kambara reactor slag to develop a method for recycling steelmaking slag. Then, the effects of holding time and carbon addition (carbon reduction) (denoted as a combination of carbon reduction/chlorination) on volatilization were examined in detail. Most of the Fe in the slag was volatilized by chlorination up to 1000 °C, independently from the type of slag. Moreover, it was possible to volatilize most of the Ti and approximately 40% of the Mg by chlorination at 1000 °C for 60 min. That is, Fe and Ti were completely separated from the slag by chlorination. Fe was volatilized below 1000 °C during carbon reduction/chlorination, and remarkable volatilization (40–90%) of Ti and P was also observed until 1000 °C. Therefore, the separation of each element using the volatilization kinetics of Fe, Ti, and P was difficult during the carbon reduction/chlorination. In contrast, when carbon was added to the chlorination residue obtained at 1000 °C for 60 min and then subjected to a carbon reduction/chlorination treatment, most of the Mg, Si, Al, and Ca remained in the solid phase up to 1000 °C, and P was the only element volatilized. The volatilization temperature (>1000 °C) and the proportion of P were lower than those of the conventional carbon reduction method of slag. Therefore, it was found that the combination of chlorination and carbon reduction/chlorination methods is effective for the separation of Fe, Ti, and P from slag. [Display omitted]