Enrichment of low grade reduced titanium slag by H₃PO₄ activation roasting and acid leaching

Titanium-containing slag produced by coal-based DR-EAF smelting was used and enriched by H₃PO₄ activation roasting and acid leaching, the phase components in the slag included anosovite, pyroxene (glass), Taki stone and spinel. The crystalline transformation of the slag during the roasting process was studied at different roasting temperatures and times, and H₃PO₄ mass content. The effects of acid leaching temperature, sulfuric acid concentration, mass ratio of liquid to solid and leaching time on the leaching rate of main impurities such as Ca, Mg, Al and Si were examined. The optimal conditions obtained were: roasting temperature 1273 K, roasting time 100 min, H₃PO₄ content 7.1%, acid leaching temperature 110°C, sulfuric acid concentration 5%, mass ratio of liquid to solid 10:1 and leaching time 120 min. Under the optimal conditions, the content of TiO₂ in the slag was raised from 52.54% to 68.31%.