A clean process for preparing ferrosilicon alloy from coal gasification fine slag by carbothermal reduction processing

The unreasonable treatment method of coal gasification fine slag (CGFS) in the industry has led to a serious waste of resources and environmental pollution, so it is of great significance to solve the problem. In this study, ferrosilicon alloy was successfully prepared from CGFS by carbothermal reduction processing, and the transformation of powdered CGFS to SiC-(Al2O3-CaO-SiO2) composite material was realized by the high-temperature vitrification process. The highest yield of ferrosilicon alloy was 35.23 % and the main compositions of the alloy were Si: 32.10 wt%, Fe: 60.52 wt%, Al: 1.93 wt%, Ca: 0.87 wt%, Ti: 2.56 wt% under the optimal smelting parameters: smelting temperature: 1800 °C; carbon content: 80 % of the theoretical value; holding time: 15 min. The final product slag was a mixed glass phase of SiC and Al2O3-CaO-SiO2, which can be used as raw material in ceramic materials preparation. Whether SiC is generated in large quantities has an important influence on the smelting process because the melted oxide will adhere to the SiC whiskers and limit the carbothermal reduction reaction. This work provides a theoretical foundation for the large-scale and high-value utilization of CGFS.