Electrochemical mechanism and flotation of chalcopyrite and galena in the presence of sodium silicate and sodium sulfite
(1. School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China;
3. Hunan Research Institute for Nonferrous Metals, Changsha 410100, China)
2. Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China;
3. Hunan Research Institute for Nonferrous Metals, Changsha 410100, China)
Abstract: The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate, respectively, as a single depressant and their mixture as a combined depressant. Flotation tests revealed that the floatability of chalcopyrite was unaffected by depressants and its recovery remained constant (>80%) within the studied dosage range. Galena flotation was severely depressed with descending depressing order as follows: combined depressant ？ sodium silicate ？ sodium sulfite. Electrochemical analysis confirmed the high affinity of depressants on the galena surface, resulting in the formation of hydrophilic species, such as lead sulfite, lead sulfate, and lead orthosilicate. The oxidation of chalcopyrite surface and depressants did not exhibit any signals; conversely, the self-oxidation of chalcopyrite was depressed. The results of cyclic voltammograms well agreed with flotation results, demonstrating that chalcopyrite primarily reacted with the collector O-isopropyl-N-ethyl thionocarbamate and that galena mostly reacted with depressants.
Key words: flotation electrochemistry; chalcopyrite; galena; sodium sulfite; sodium silicate