Effect of sodium hypochlorite as a depressant for copper species in Cu-Mo flotation separation

• Published in: Minerals engineering 2023-10, Vol.201, p.108166, Article 108166
• Main Authors: Montoya, Arait, Reyes, Juan L., Reyes, Iván A., Cruz, Roel, Lázaro, Isabel, Rodríguez, Israel
• Format: Article
• Language: English
• Subjects: Chalcopyrite; Depressant; Molybdenite; Separation; Sodium hypochlorite
• ISSN: 0892-6875; 1872-9444
• DOI: 10.1016/j.mineng.2023.108166

•The effect of sodium hypochlorite as an oxidizing agent depressed chalcopyrite in flotation.•A decrease in the recovery of chalcopyrite was observed as the NaClO dosage increased.•Mixed potential measurements were made to confirm the best NaClO concentration.•Molybdenite recovery remained almost constant at different NaClO dosages.•The formation of soluble species was observed upon molybdenite floatability due to oxidation. One alternative to replace conventional depressants in Cu-Mo separation is using oxidizing agents to promote the formation of products on chalcopyrite that render its surface hydrophilic and thus favor its depression. This work provides a study to understand how sodium hypochlorite can act as a depressor for chalcopyrite in Cu-Mo flotation separation. The effect of NaClO in flotation tests was evaluated by means of electrochemical techniques, scanning electron microscopy (SEM), Fourier transform infrared analysis and contact angle measurements. The flotation results showed a selective depressant effect at a dosage of 1,020 g/t NaClO, conditioning time of 5 min, and pH 7. The mixed potential showed that the oxidation of chalcopyrite and molybdenite is possible through the addition of NaClO. The SEM observations showed changes in oxidized chalcopyrite morphology, which is supported by the decreasing contact angle change; no morphological changes were observed on molybdenite. FTIR analyses showed the characteristic peaks of the OH group after chalcopyrite was treated with NaClO; when molybdenite was treated with NaClO, the FTIR spectrum did not show changes. A scheme is proposed for the formation of oxidation species.