A hydrometallurgical process was developed for the preparation of commercial grade antimony trioxide (Sb2O3) from indigenous antimony ore. The developed process includes oxidative chlorination leaching of stibnite (Sb2S3) concentrate assaying 64.86% Sb prepared from indigenous low-grade ore containing 20.16% Sb using ferric chloride (FeCl3) solution in acidic medium as lixiviant followed by purification, precipitation and crystallization of antimony trioxide as end product. An effort was made to investigate the effect of all the important variables encountered in leaching of metallic sulphide minerals in order to establish the best process conditions for the extraction of antimony and subsequent preparation of antimony trioxide. The experiments were carried out on laboratory scale and the effect of various process variables on the dissolution of antimony from stibnite concentrate was studied by single factor variation method arranged in a sequential manner. An industrial grade antimony trioxide having 99.70% purity with 90.72% yield has been prepared. The developed process is technically feasible and environmentally friendly.

Muhammad Arif Bhatti, Ahmad Adnan, Abdul Ahad, Kamran Raza Kazmi and Adnan Akram