Chrome ore mineralogy and the furnace mass and energy balance

The effect of ore mineralogy on ferroalloy smelter operation is not sufficiently understood. The ore mineralogy can influence energy and reductant requirements, melting and reaction rates, and effectiveness of prereduction. These are all important factors to consider for furnace design, warranting a deeper study of the effect of ore mineralogy on ferroalloy production processes. This work focuses on smelting furnace mass and energy balances. Furnace mass and energy balances are among the most fundamental calculations done on a regular basis, from the project feasibility stage right through to everyday operations. Whether the energy balance is calculated by a tried and tested spreadsheet calculation, or by applying thermodynamic fundamentals using tools such as FactSage or EMSIM, most engineers simply use a chemical analysis of the raw materials. This ignores the potential effect of the ore's true mineralogical composition and may cause errors, the magnitude of which are not fully understood. In this paper we present the results of mineralogical analyses of South African, Zimbabwean, and Khazakstan chrome ores and compare energy balance results based on standard chemical assays to results based on mineralogical information.