Purification and Removal of Hematite from Talc by Acid Leaching Assisted by Chlorination Techniques

Abstract

Talc is an important industrial commodity due to its wide-ranging intrinsic properties; however, the presence of iron oxide hinders its industrial utilization. Herein, we report the purification of Pakistani talc through acid leaching assisted by chlorination techniques. Among various acids (i.e., HF, HCl, H 2 SO 4 , HNO 3 , H 3 PO 4 , Aqua Regia, H 3 BO 3 , and CH 3 COOH), HF was the most effectual, removing up to 67% of iron oxide at optimized conditions of temperature, 90-95 °C; time, 120 min; HF concentration of 5%; and at a pH of 1. In the second step, chlorination of the talc sample was performed separately by both wet chlorination and dry chlorination. Wet chlorination was carried out using KMnO 4 and HCl in slurry phase which shown about 52% removal of iron oxide, whereas dry chlorination with CaCl 2 at high temperature attained about 48% removal of iron oxide from talc sample. Further, the wet chlorination of HF leached samples was also performed under optimized conditions which showed up to 87% iron oxide removal. The original and treated talc samples were characterized by EDX and XRD analysis to monitor the changes in the elemental and mineralogical composition of the talc. It can be concluded that HF leaching followed by wet chlorination is an effective method for the upgradation of low-grade Pakistani talc ores.