Batch and Pilot Plant Flotation studies on Khetri copper ore

Abstract

Comprehensive Laboratory and Pilot Plant studies have been made on the flotation of a low grade copper ore from Khetri, Rajasthan. The sample assayed 0.80% Cu, 18.63% Fe, 3.08% S, 54.65% SiO2, 9.62% Al2O3, 4.54% MgO, 0.13 dwt./ton Au and 2.37 dwt./ton Ag. Quartz, chlorite and garnet formed the major transparent gangue in the sample whereas pyrrhotite and magnetite were the chief opaque gangue followed by pyrite-mercasite and traces of pentlandite. Batch flotation studies employing potassium ethyl xanthate as collector for chalcopyrite and lime as a department for other sulphide gangue indicated that the optimum grind was 62.5 to 73.3% passing through 200 mesh. Two cleanings of the rougher float with recirculation of the middlings after regarding to -200 mesh yielded final recoveries of 81.4 and 81.7 % Cu for a concentrate grade of 22 and 24.5% Cu. Higher Xanthate Aerofloat 238 gave slightly better results. Flotation of copper tailings after acidification to a pH of 5.5 and using potassium amyl xanthate yielded a final pyrrhotite-pyrite concentrate weighing 5.6% with an assay of only 30.0% S. Continuous pilot plant studies more or less confirmed the results obtained on a batch scale. Regarding of the entire refloat concentrate to get good copper concentrate was found to be unnecessary.