CO2-Minimized Ferrochrome Production Utilizing Silicon Wafer Cutting Slurry as an Alternative Reductant

Direct emissions due to the use of carbon-based fossil-reducing agents contribute to the overall CO2 emissions of pyrometallurgical production processes. This study investigated the replacement of fossil coke by silicon-rich cutting waste from the solar wafer cutting process to produce ferrochrome in an electric arc furnace. Laboratory test work and thermochemical simulation were carried out to examine the product quality at various additions of cutting waste and lime. The experimental trials resulted in products in accord with international standards, however, adjusting the slag composition by the addition of lime was necessary, otherwise high silicon contents in the alloys were obtained. Due to the highly exothermic reaction of silicon with iron- and chromium oxides, the silicothermic reduction results in a decreased specific electric energy consumption compared to the carbothermic reduction according to the thermochemical simulation. Low phosphorus and sulfur contents in the alloy might result in premium prices, aiding the economic viability of the process.

Automated summary

This study investigates the replacement of fossil coke with silicon-rich cutting waste to produce ferrochrome, resulting in products that meet international standards. Adjusting the slag composition with lime is necessary to control silicon levels in the alloys. Thermochemical simulation shows that silicothermic reduction decreases specific electric energy consumption compared to carbothermic reduction.