Abstract
	Upgrading of a low-grade titanium slag (~55% TiO2) with high silica, calcia,  magnesia and iron contents has been studied using sulphation roasting technique followed by acid leaching. XRD analysis of the sulphated slag reveals the presence of kennedyite (Fe2O3. MgO. 3TiO2), rutile (TiO2), calcium sulphate (CaSO4) and calcium silicate phases (3CaO.SiO2). The residue after leaching contains mainly kennedyite and rutile phases and free silica (SiO2) with traces of calcium silicate phase (CaO.SiO2). Removal of 80% calcium, 37% magnesium and 20% iron is achieved for sample treated at 800 oC for 60 min. Above this temperature the surface of the slag pellet becomes compact and retards the diffusion of the sulphating gas mixture into the pellet core and consequently the sulphation extent decreases. The upgraded slag contains about 72% TiO2. Acid leaching of this slag prior to sulphation roasting process is necessary to remove most of the iron in the ferrous state. This pre-leaching step enhances the break down of the slag structure and promotes its sulphation extent and helps removal of about 40% calcium, 20% magnesium and 40% iron. Synthetic rutile that has about 83% TiO2 can be produced via process described in this work. Thermodynamic calculations give rational explanations of the obtained results and the suggested reactions.