Carbothermal Reduction of Stainless Steel Dust and Laterite Nickel Ore: Slag Phase Behavior Regulation and Self-pulverization Control Mechanism

Abstract

Stainless steel dust is a type of high basicity iron containing solid waste from the iron and steel smelting industry. In this study, the carbon-containing composite briquettes were prepared by adding low basicity laterite nickel ore and stainless steel dust, and the valuable metals Fe, Cr, and Ni were recovered by carbothermal reduction. The results show that the addition of laterite nickel ore into CBSL (carbon containing composite briquette of stainless steel dust and laterite nickel ore) effectively improves the recovery of metal Fe, Cr and Ni and the self-pulverization rate of reduction slag. The reduction temperature is 1450°C, the reduction time is 30 min, the FC/O (molar ratio of fixed carbon to oxygen) is 1.0, and the laterite nickel ore addition is 6%, the recoveries of metal Fe, Cr and Ni are 92.1%, 90.1% and 91.6%, respectively, and the self-pulverization rate of the reduction slag reaches 91.5%. The Ca2SiO4 phase content of the reduced slag at high temperature is 71.8%, and the reduced slag system is located in the orthosilicate Ca2SiO4 region of the phase diagram, which effectively improves metal recovery, enables efficient separation of the reduced product and reduces energy consumption for subsequent processing.