Phosphorus (P) is an essential element not only for human life but also for crop growth and for the production of functional materials. On the other hand, P is classified as a depleted element. Therefore, developing methods to recover P from secondary P resources is important. This study aimed to selectively recover of P from steelmaking slag by combining chlorination, steam reforming, and carbon reduction. First, detailed conditions were investigated to prepare Fe-free chlorinated residue by chlorination of the slag. Subsequently, the chlorinated residue was dechlorinated via steam reforming, and then selective volatilization of P were investigated by carbon reduction of the dechlorinated residue. Although chlorination of slag up to 1000°C enabled selective removal of Fe, selective separation of P was difficult during carbon reduction of this chlorinated residue. This was considered due to the residual chlorine in the chlorinated residue. Therefore, de-chlorination of the chlorinated residue via steam treatment was investigated. The results showed that heating at 1000°C could almost completely remove chlorine from the solid phase. Subsequent carbon reduction of this steam-modified chlorinated residue allowed only P to volatilize. These findings demonstrate that combining chlorination, steam reforming, and carbon reduction processes on steelmaking slag enables the selective, highly efficient volatilization, separation, and recovery of P alone.
Liu et al. (Thu,) studied this question.