Experimental study on roast-leaching of scandium and titanium from a clay mine in Sichuan

For the scandium-, titanium- and rare earths-bearing clay ore from southern Sichuan, preliminary experiments of sodium salt roasting-acid leaching, direct leaching, sulfatizing roasting-water leaching, and blank roasting-acid leaching were conducted. Results showed that the recovery of scandium and titanium by direct leaching and and blank roasting-acid leaching was unsatisfactory. The recovery of titanium by sulfatizing roasting-water leaching was high, but the recovery of scandium was relatively low. Experiment results of sodium salt roasting-acid leaching showed that under roasting conditions of Na2CO3 dosage 80%, roasting temperature 800^oC, roasting time 1h, and under leaching conditions of sulfuric acid concentration 10 vol. %, liquid to solid ratio 20:1, leaching temperature 60^oC, agitation leaching time 2h, the leaching rates of scandium and titanium were 89.98% and 80.55%, respectively. Liquid to solid ratio has a significant effect on the leaching rates of scandium and titanium, and increasing liquid to solid ratio can temporarily solve the poor filterability problem caused by silicic acid.