The effect of tartrate on the mild leaching of low-grade polymetallic complex chalcopyrite ore in acidic ferric chloride solution

• Published in: New journal of chemistry Vol. 47; no. 27; pp. 12934 - 12943
• Main Authors: Liu, Xin-Jie, Liao, Yalong, Liu, Qingfeng, Wu, Min
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 10.07.2023
• Subjects: Anodic dissolution; Chalcopyrite; Charge transfer; Dissolution; Electrode polarization; Ferric chloride; Leaching
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d3nj01998e

The mild leaching of low-grade polymetallic complex chalcopyrite ore (LPCCO) is of great significance, but is limited by the passive film. In this work, the leaching of LPCCO at atmospheric pressure and 298-358 K in the ferric chloride solutions (pH = 0) without and with tartrate was studied. The reasons why tartrate improves the leaching/dissolution were further investigated by electrochemical characterizations and surface analyses. Results showed that in 15 h and 358 K, the Cu extraction rate increased to 95.2% from 81.6% after the addition of tartrate. The electrochemical study results indicated that tartrate had significant effects on OCP, the anodic peak (A 1 ) of LPCCO dissolution, current crossing loop related to oscillation/re-activation, resistances of charge transfer (CT) across solution-film and film-LPCCO interfaces, measure of the non-ideality of capacitor related to the roughness of passive film, and polarization current. XPS results suggested that tartrate decreased Cu 2+ and Pb( ii ) contents and increased S 0 content in residues. Additionally, SEM-EDS signified severer LPCCO dissolution when the tartrate was present. A mechanism of LPCCO dissolution was proposed. Tartrate/tartaric captures metal ions by complexation of two -COO − , which facilitate CT, and possibly, incidentally takes S 0 away by the organic terminal (-CH) attacking S 0 . As the tartrate complex departs from the surface, S 0 is pushed away by the resetting of -OH. The released S 0 is forced to deposit on the adjacent point and heaps together. This work provides insights into the leaching behavior of LPCCO and the great potential of tartrate. The mild leaching of low-grade polymetallic complex chalcopyrite ore (LPCCO) is of great significance, but is limited by the passive film.