Investigating the role of Orfom® D8 in the depression of chalcopyrite in its separation from molybdenite – application to water types

Molybdenite commonly coexists with chalcopyrite in porphyry copper deposits, necessitating the efficient separation of these minerals through froth flotation. Depressants play a crucial role in achieving effective metal separation during flotation. While conventional inorganic depressants such as sodium hydrosulfide (NaHS) offer satisfactory metallurgical performance, they pose significant drawbacks, including strong odour, toxicity, and inconsistent grades. Globally, there has been a shift towards environmental sustainability with emphasis on freshwater conservation. Some studies have shown a beneficial effect of seawater flotation, while others have shown a deleterious effect of Ca and Mg ions on the flotation of copper and molybdenum. This study investigated the performance of Disodium Carboxymethyl Trithiocarbonate (Orfom® D8) as an organic depressant in the separation of chalcopyrite from a bulk Cu-Mo concentrate. Additionally, the effect of different water chemistries on their flotation performance was investigated. Response surface methodology (RSM) using a central composite design (CCD) was employed to optimize flotation conditions. The independent variables included depressant dosage, collector dosage, conditioning time, and pulp pH. The model showed strong agreement with experimental data, identifying optimal conditions at a depressant dosage of 5000 g/t, a collector dosage of 10 g/t, a pH of 8.5, and a conditioning time of 1 min. These conditions were then used to evaluate metallurgical performance across different water types. The results revealed a significant impact of water chemistry on flotation performance. Overall, this study offers valuable insights into improving the separation of chalcopyrite from molybdenite and can serve as a guide for industrial plant practice.