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

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AbstractThe extraction of metal from sulfide mineral is usually accompanied by the emission of sulfur‐containing gas (e.g., SO2), which will cause serious pollution to the environment. In this work, a sulfur‐emission free route for preparing ultrafine molybdenum disilicide (MoSi2) powder by silicothermic reduction of MoS2 with the desulfurization agent of lime was proposed. The internal MoS2‐Si mixture is wrapped in an external desulfurization layer composed of lime. After the reaction is completed, the prepared MoSi2 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 MoS2 is transformed to sulfur‐containing gas SiS, which can be fully captured by lime to generate CaS, Si, and CaSiO3. For the raw material with a MoS2:Si molar ratio of 1:4, after reacting at 1000, 1100, and 1200°C for 2 h, the average grain sizes of the obtained MoSi2 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 MoSi2 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.