Study of alkaline hydrometallurgical process for stibnite flotation tailings reprocessing: Semi-pilot antimony leaching

Nowadays, tailings management and scarcity of raw materials are both topics that are much discussed in the mining sector. Recycling is therefore a sustainable method of extracting metals from secondary resources for tailings management and the supply of critical metals such as antimony. Alkaline leaching was carried out using mixture of sodium sulfide (Na₂S) and sodium hydroxide (NaOH). Optimisation tests at laboratory scale allow the optimum parameters to be set at 25 % pulp density, 0.97 M Na₂S, 2.5 M NaOH, 70 °C, 300 rpm for 60 min. The antimony dissolution rates were 99.13 % and 97.00 % at bench and semi-pilot scale, respectively. On the other hand, hydrogen peroxide (H₂O₂) was used to precipitate antimony from the leach solution. About 99 % of Sb precipitation efficiency was achieved under 5/1 Pregnant Leach Solution (PLS)/Hydrogen peroxide (H₂O₂) ratio, 30 °C, 300 rpm for 90 min.