Selective Precipitation of Titanium, Magnesium, and Aluminum from the Steelmaking Slag Leach Liquor

Abstract

In this study, a separation process for the selective precipitation of titanium, magnesium, and aluminum from the steelmaking slag leach liquor is developed. This process involves hydroxide precipitation using a single precipitant (NaOH) to selectively recover these elements in a sulfate system without the use of other precipitants, stabilizing agents, or oxidizing/reducing agents. The systematic investigation is carried out to study the effect of several operating parameters, namely precipitation pH level, reaction temperature, stabilization time, and precipitant reagent type, on the metal recovery and product purity. After the process optimization, 83% titanium precipitate purity with 85% recovery alongside >90% magnesium and aluminum precipitate purity with 100% recovery are achieved. The quantification and characterization of the product solids and liquors are carried out to ensure the feasibility and profitability of the developed process. For the industrial-scale operation, the mass balance of the process at a large scale is estimated. The developed process proves to be a promising technique to produce several value-added solid products including TiO2, Al(OH)3, and Mg(OH)2 from the steelmaking slag leach liquor and in turn, help close the material's life cycle.