Detoxification and comprehensive recovery of stainless steel dust and chromium containing slag: Synergistic reduction mechanism and process parameter optimization

Abstract

Stainless steel dust and chromium containing slag are representative harmful solid wastes produced in modern iron and steel metallurgy industry. Based on the study of stainless steel dust reduction, the direct reduction process with low energy consumption and high efficiency was obtained by changing the addition amount of chromium containing slag and the conditions of reduction process system. The results show that with the addition of chromium containing slag, the basicity of raw materials decreases, the recovery of metal is improved, and the self-pulverization effect of reducing slag is improved. The optimum process conditions are as follows: the mixing ratio of stainless steel dust to chromium containing slag is 94%: 6%, the reduction temperature is 1400 °C, the reduction time is 25 min, the FC/O is 0.9, the recoveries of Fe, Cr and Ni in the reduction products are 90.5%, 90.6% and 91.2%, respectively, the grades of Fe, Cr and Ni in Fe-Cr-Ni-C alloy are 61.3%, 19.9% and 3.7%, respectively, and the contents of harmful components such as S and P are very low. The self-pulverization rate of reduction slag can reach 92.8%, and the residues of metal Fe, Cr and Ni in reduction slag are 134 ppm, 96 ppm and 129 ppm, respectively.