Separation of Iron and Calcium from a BSSF Steelmaking Slag Through Acid Leaching

Considering the BSSF steelmaking slag generated in a Brazilian steelwork, this study aimed to separate iron and calcium from it to increase its iron content or produce Fe2O3 and CaO by selective precipitation. The methodology involved acid leaching of an industrial sample using different concentrations of hydrochloric acid (HCl). The results showed that leaching with a 2 mol.L-1 HCl solution extracted 63.6% of the CaO from the slag, increasing the Fe content from 27.4 to 37.1 wt%. Further leaching with a 5 mol.L-1 HCl solution resulted in an impressive transfer of 86.8% of iron and 90.7% of CaO to the liquid solution. Subsequently, iron and calcium were separated by selective precipitation; Fe(OH)3 was precipitated by adding ammonia and calcinated to produce Fe2O3, while calcium carbonate (CaCO3) was obtained by adding sodium carbonate and calcinating it to produce CaO. This process presents a viable approach to valorize BSSF steelmaking slag, yielding valuable materials for in-house production at steel plants.