Effect of basicity on beneficiated chromite sand smelting process using submerged arc furnace

Abstract

Ferrochrome is an important alloy in stainless steel making due to its contribution to high strength and corrosion resistance. In this present study, ferrochrome was derived from Indonesian chromite sand with low-grade Cr/Fe ratio. In order to improve the ratio, beneficiation process such as pre-magnetic separation and reduction process at 1000°C for 60 minutes was required. The process followed by another magnetic separation, thus the Cr/Fe ratio was increased from 0.9 to 1.6. The reduction process used coconut shell charcoal as reductant and limestone as an additive. The beneficiated sand chromite was briquette using bentonite as a binder in 2 wt.% before it was smelted in a submerged electric arc furnace to produce ferrochrome. Basicity was controlled by the addition of limestone and it was varied from 0.4-1.6. Furthermore, the composition of ferrochrome was analyzed by using X-Ray Fluorescence. From this experiment, the result showed that chromium recovery and specific energy was decreased with the increasing of slag basicity.