BENEFICIATION STUDIES ON LEAN GRADE COPPER ORE BY SELECTIVE FLOCCULATION AND FLOTATION TECHNIQUES

摘要

Low grade copper ore from Mpanda Mineral Field (MMF) was subjected to selective dispersion-flocculation and flotation processes to benef iciate chalcopyrite. The mineralogical characterization indicated that chalcopyrite, pyrite and quartz were the main minerals. The adsorption of acacia gum (AG) on chalcopyrite exhibited an L2 type isotherm of the Giles classification, with the maximum adsorption at pH 2.3, while its adsorption on silica was negligible. The FTIR spectroscopic investigations indicated that hydrogen bonding and chemical interaction forces were responsible for the adsorption of AG on chalcopyrite. The ground MMF ore was subjected to selective dispersion-flocculation using 30 ppm of sodium trisilicate (STS) and 120 ppm of AG yielding the chalcopyrite grade of 11.5 % after three desliming stages. The flotation of the flocculated fraction was carried out using potassium amyl xanthate and potassium ethyl xanthate (1:1) 30 g/t, Na_2S 40 g/t as the sulphidising agent, pH 10.3,2.5 min as the flotation time and methyl isobutyl carbinol (MIBC) as the'frother yielding the copper grade and recovery of 21.3 and 93.3 % respectively while that of silica was 5.3 and 4.8 % respectively in the rougher concentrate. The cleaner flotation of the rougher concentrate yielded the copper grade and recovery of 27.3 and 87.2 % respectively, while that of silica was 1.2 and 0.5 % respectively in the cleaner concentrate.