A novel approach to prepare high-purity Si and Si/TiSi2 materials simultaneously using Ti-bearing blast furnace slag

Abstract

A new approach was proposed to prepare multi-products, high-purity Si powders, bulk Si, and Si/TiSi2 materials (eutectic Si-Ti), simultaneously using inexpensive low-purity Si (99.3%) and metallurgical waste—Ti-bearing blast furnace slag. TiO2 in Ti-bearing blast furnace slag was first reduced by Si to form a Si-Ti alloy which was then separated into high-purity bulk Si (99.97%) and Si/TiSi2 materials (99.4%) using directional solidification. The bulk Si could be repeatedly recycled as a reductant, or further upgraded to prepare super-pure Si powders (99.995%) after acid leaching. The new approach shows many sustainable and economic benefits, such as no carbon gas emission, low acid consumption and Si loss, recyclable Si reductant, widely-used multi-products employing one approach, and rapid consumption of accumulated Ti-bearing blast furnace slag.