Column flotation to recover molybdenite from Rakha Copper Concentrate - Part I: Conventional rougher flotation of molybdenite with sodium hydrogen sulphide

Rakha Copper Concentrator near Ghatsila, Bihar, India, produces 40 TPD bene ficiated copper concentrate containing 24-25% Cu and 0.25% Mo. The in-house R&D of Indian Copper Complex at Ghatsila developed a flowsheet to recover molybdenite from the rakha copper concentrate which consists of dewatering rougher flotation, followed by 9 stage cleaning with two intermediate grind ing stages to produce concentrate containing SOR Mo with 80% recovery. In a n endeavor to simplify the flowsheet detailed studies were carried out on t he copper concentrate to optimize the molybdenite rougher flotation and to size the: cells needed for the commercial plant. Molybdenite present in the copper concentrate was found to be fast floating. In presence of sodium hy drogen sulphide as depressant, nearly 98% of the weight rejection was achie ved in 5 minutes of batch flotation. Conditioning with NaHS at 40% solids a nd flotation at around 35% solids in presence of 15 ml/l NaHS a rougher Mol ybdenite concentrate containing 4% Mo with around 90% recovery could be ach ieved. The aspects related to sizing of the rougher flotation cells needed for the commercial circuit are also discussed.