A Sustainable Method for Ti, Al and Mg Recovery from Titanium-Bearing Blast Furnace Slag Coupled with CO2 Sequestration by Leaching Residue

A sustainable method for Ti, Al, and Mg recovery from titanium-bearing blast furnace slag (TBBFS) coupled with CO2 sequestration by leaching residue is proposed. The results show that the original mineral phase of the TBBFS could be destroyed by ammonium sulfate roasting, in which the valuable metals were converted to sulfates. Subsequently, Ti, Al, and Mg in the roasting slag were effectively extracted with dilute sulfuric acid leaching. The Ti, Al, and Mg in the solution could be separated and recovered by the stepwise hydrolysis method. The leaching residue was used for CO2 sequestration through the carbonation reaction. Under optimal conditions, the fractional conversion of calcium sulfate reached 98.83%, while an ammonium sulfate product was obtained. The proposed process achieves not only the recovery of Ti, Al, and Mg from the TBBFS but also the recycling of ammonia and sulfur based on the carbonation reaction of the leaching residue.