Abstract:Flotation reagents have a complex behaviour in the beneficiation of base minerals in clayey ores. Interaction effects of reagents on the efficiency of copper flotation for a highly clayey low-grade sulphide ore were investigated using a central composite design. Preliminary results showed that sodium-isopropyl-xanthate (SIPX) and O-isopropyl-N-ethyl-thionocarbamate (IPETC) were found to be the most efficient collectors in the presence of lime as the pH regulator. The effects of dosage of collectors (SIPX and IPETC) and the dosage of methyl-isobutyl-carbonyl (MIBC) as frother on the separation efficiency were evaluated at different pH levels. Based on the analysis of variance (ANOVA), the interaction effects of the collector-pH and collector-frother were significant for the separation efficiency. At the low level of collector dosage, increasing pH from 9 to 11 enhanced copper separation efficiency from 81% to 86% for IPETC and from 77% to 86% for SIPX. Results of ANOVA showed that the maximum copper separation efficiency (88.7%) was obtained at the dosages of 8.6 g/t SIPX, 7 g/t IPETC and 20 g/t MIBC at pH 11. Finally, it was concluded that a mixture of SIPX and IPETC collectors was more suitable to treat highly clayey sulphide ores.

Key words: flotation; copper sulphide; reagent; interaction effect; reject ore