Ozonation leaching of a complex sulfidic antimony ore in hydrochloric acid solution

• An ozonation leaching process for a complex sulfidic antimony ore is reported.
• High antimony extraction and low iron dissolution are obtained in the HCl solution.
• Decomposition of stibnite is easier than pyrite in the ozonation leaching.
• The Eh-pH diagram of antimony and iron is used for the analysis of results.
• The solubility of antimony in the HCl concentration is discussed.

Selective dissolution of stibnite from a complex sulfidic antimony ore containing pyrite by ozonation leaching in hydrochloric acid solution has been studied in the paper. Effects of hydrochloric acid concentration, leaching time, temperature, gas (ozone and oxygen mixture) flow rate and liquid/solid ratio on antimony extraction and iron dissolution have been examined. The results show that the leaching efficiency (%) of antimony increases with the temperature (from 35 °C to 65 °C) and hydrochloric acid concentration (from 3.0 mol/L to 4.5 mol/L). In comparison, the iron dissolution remains constant in these ranges. In addition, it is noted that the decomposition of stibnite is easier than that of pyrite. High antimony extraction (94.3%) with low iron dissolution (2.3%) is achieved under the following leaching conditions: 4.5 mol/L hydrochloric acid concentration, 2.0 L/min gas flow rate and 8:1 of the L/S ratio, leaching for 4.0 h at 65 °C. These results reveal that ozonation leaching of the complex sulfidic antimony ore in hydrochloric acid solution is a promising technology.