Silicate slag system in carbothermal reduction of stainless steel dust: Strengthening mechanism and stable regulation

Abstract

The crystalline transition of the silicate Ca2SiO4 formed during stainless steel dust carbothermal reduction cooling is the key to the efficient separation of the reduced metal and slag. With stainless steel dust as the raw material and low basicity laterite nickel ore as an additive, the self-pulverization rate, the self-pulverization slag content and the phase transition of the reduced slag for different basicity conditions were studied. Meanwhile, the production and control mechanism of the silicate Ca2SiO4 has been elucidated in conjunction with thermodynamic calculations. It was shown that with 6% laterite nickel ore was added to the stainless steel dust, the basicity of the reduced slag system was reduced to 2.1, the self-pulverization rate of the reduced slag reached 90.35% and the self-pulverization slag content reached 88.65%. The dominant phase in the self-pulverization slag system is Ca2SiO4, which effectively enhances the silicate Ca2SiO4 system of the reduced slag and enables efficient separation of the reduced slag of stainless steel dust from the reduced metal. Non-toxic and harmless high-efficiency reduced slag can be used as a high-quality raw material for ceramics and cement, enabling a comprehensive application and sustainable development of solid waste materials for stainless steel dust.