Optimisation de la consommation d’acide sulfurique à la lixiviation des rejets de Kingamyambo

This work focuses on optimizing the consumption of sulfuric acid in the leaching of Kingamyambo waste. In fact, the Kingamyambo rejects are old rejects treated by flotation at the Kolwezi Concentrator and still containing copper and cobalt in considerable proportions. These rejects grade on average 1% Cu and 0.3% Co and also contain calcite, magnesite, dolomite, and talc. Although feasibility studies initiated by the Générale des Carrières et des Mines reported excessive acid consumption of around 257 kg/acid per ton of ore, magnetic separation was proposed to eliminate a portion of the gangue responsible for this excess consumption prior to acid leaching of the concentrate. Pilot-scale magnetic separation tests at Kamfundwa produced a final concentrate averaging 2.2% copper and 0.6% cobalt, with recovery rates of 59.2% for copper and 36% for cobalt. Acid leaching tests on the concentrate under optimal conditions (60 g/L acidity, 30% solid percentage, and 90 minutes of leaching) achieved metallurgical performances of 84.41% and 49.8% for copper and cobalt leaching yields, respectively, with a total acid consumption of 216.67 kg per ton of concentrate. The results indicate that it is feasible to retreat the Kingamyambo rejects through magnetic separation followed by acid leaching with acceptable acid consumption.