Low Energy Process Development for Chibuluma Copper Tailings

Copper froth flotation tailings containing 1.19 and 0.97 wt% total and acid-soluble copper, respectively, from Chibuluma mines in the Copperbelt province of Zambia were characterized by SEM and XRD techniques. The major phases in the feed material were malachite, chrysocolla, pseudo malachite, chalcocite, quartz, biotite, orthoclase, calcite, etc. Screen analysis revealed that the tailings were coarse as only 9.17 wt% were less than 0.075 mm. With the purpose of establishing a low energy processing route, gravity concentration, froth flotation, and flotation–leach tests were carried out on the material. Gravity concentration upgraded copper up to 15.32 wt% at a cumulative recovery of 59.6%. On the other hand, a concentrate grade of 21.59 wt% was obtained via froth flotation but recovery was lower (49.68%). Therefore, the tailings from froth flotation were leached out and a leach efficiency of 97.92% was obtained such that the final tailings only had 0.02 wt%. As a result, it was concluded that the tailings should be processed via flotation–leach process to ensure maximum recovery of copper (both sulphide and oxide).