Slag to product: Unlocking titanium-bearing slag value via selective leaching of amorphous titanium phase

• Revealing selective leaching mechanism for amorphous titanium-bearing phases. • Identifying leaching and co-precipitation effect of oxalate acid as leaching reagent. • Partial dissolution of TBFS yielded a commercial grade product with 44.29% TiO 2 . • Leachates used for synthesis high purity zeolites as by-products. Titanium-bearing blast furnace slag (TBFS) is a valuable solid waste produced during ironmaking using titanium-bearing iron ores. However, its complex chemical composition and limited pre-processing methods restrict the efficient utilization of TBFS, especially under increasingly stringent environmental, social, and governance (ESG) requirements. In this study, we assess organic acid activation combined with commonly-used HCl and NaOH leaching processes to partially dissolve the slag with a medium grade of 23.5% TiO 2 , which is upgraded to 44.3% TiO 2 in the leaching residue. The results revealed that the amorphous titanium-bearing glass phase was preferentially dissolved during leaching, while the crystalline perovskite structure was retained due to its chemical stability. In addition, the alkaline wash liquor is almost pure silicon solution which can be used as feed for producing high purity zeolites as commercial products. This Slag to Product strategy can almost utilize all leaching liquor and leaching residue which provide the closed-loop direction for utilization of TBFS for high valued products.