Selective leaching behavior and kinetics of wasteful Titanium-bearing blast furnace slag via low concentration hydrochloric acid

Titanium-bearing blast furnace slag (TBFS) is rich in metallic resources but poses considerable environmental risks during long-term storage. Conventional selective extraction methods are limited by high acid consumption, prolonged processing time, and excessive energy requirements. This study developed a thermodynamically controlled selective leaching approach using low-concentration hydrochloric acid (HCl) to enhance elemental recovery and reduce environmental impact. We established a leaching system using 3.0 mol/L HCl at 373 K for 120 min, leveraging the temperature-dependent dissolution behavior of perovskite (> 353 K). The leaching efficiencies of Ca, Mg, and Al reached 93.5 %, 95.2 %, and 95.3 %, respectively, while Ti and Si exhibited minimal dissolution at 2.3 % and 1.7 %, respectively. Consequently, the TiO₂ content increased from 18.5 % to 38.2 %, enabling effective Ti enrichment and providing a basis for high-value product synthesis. Kinetics analysis indicated that the process was controlled by internal diffusion, with Ti and Si undergoing dissolution-reprecipitation and ultimately forming solid surface layers on the residual particles. These findings support the efficient extraction of valuable elements from TBFS while promoting industrial circularity and environmental sustainability.