A novel sulfur‐emission free route for preparing ultrafine MoSi₂ powder by silicothermic reduction of MoS₂

Abstract

The extraction of metal from sulfide mineral is usually accompanied by the emission of sulfur-containing gas (e.g., SO 2 ), which will cause serious pollution to the environment. In this work, a sulfur-emission free route for preparing ultrafine molybdenum disilicide (MoSi 2 ) powder by silicothermic reduction of MoS 2 with the desulfurization agent of lime was proposed. The internal MoS 2 -Si mixture is wrapped in an external desulfurization layer composed of lime. After the reaction is completed, the prepared MoSi 2 can be easily separated from the desulfurization layer by using a non-chemical method. In addition, when the reaction temperature is higher than 1000°C, almost all S in MoS 2 is transformed to sulfurcontaining gas SiS, which can be fully captured by lime to generate CaS, Si, and CaSiO 3 . For the raw material with a MoS 2 :Si molar ratio of 1:4, after reacting at 1000, 1100, and 1200°C for 2 h, the average grain sizes of the obtained MoSi 2 powder are approximately 100, 300, and 800 nm, respectively. Moreover, when the reaction time is prolonged from 2 to 6 h at 1000°C, the average grain size of the acquired MoSi 2 powder is about 200 nm, and the residual sulfur content is about 0.12%. This work provides a new insight to extract metals or metal compounds from sulfide ores without releasing sulfur-containing gas.