Selective stabilization of chromium and sustainable treatment of stainless steel slags

Selective stabilization of chromium and sustainable treatment of industrial stainless steel electric arc furnace slags was investigated. The crystallization and phase distribution of stainless steel slags after equilibration at 1500 °C with varying basicity between 1.8 and 1.0 using quartz sand were studied. Results showed chromium in the slag can be fully stabilized into the Cr-spinel phase, which accumulate at the crucible bottom under the influence of gravity at a basicity of 1.2. The top liquid portion corresponding to about 72 % of the total slag can be quenched to an amorphous phase after a slag discharge treatment with the bottom residual solid portion in the form of a Cr-spinel enriched slag. The leaching experiments of the two separated slags were implemented according to the standard HJ/T 301–2007, and the Cr leaching concentrations were 0.059 mg/L and 0.136 mg/L, respectively. This was within the national comprehensive utilization standard of Cr-bearing solid wastes. Furthermore, the feasibility analysis of operation and potential application to the stainless steel industry was also addressed to provide the fundamentals for industrial scale utilization of stainless steel slags.