Modified-three-product column (3PC) flotation of copper–gold particles in a rougher feed and tailings

Results of copper–gold rougher-flash flotation in a three-product column (3PC) are presented, and separation parameters are compared with results of an existing industrial small mill (rougher–scavenger–cleaner treating 100–120 t/day). This 3PC cell yielded 2%–5% richer Cu and Au concentrate grades at higher recoveries (5% RCu and 15% RAu, respectively) while consuming only 5% of the circuit energy and occupying 10% of the actual footprint. The flotation of the fresh tailings from the same industrial circuit was also successful in recovering more than 40% of the copper losses and 25% of the gold losses with concentrate grades that were high enough to permit recycling of the recovered copper and gold. The cleaning action of the cell is due to the selective separation of the third product (froth drop-back), which corresponded to a low-grade material amenable for discard. This third product is primarily composed of misplaced (entrained) gangue particles, and the mass recoveries were found to be a function of froth height with an optimal value varying from 40 to 60 cm. Results are discussed in terms of the high potential of this 3PC cell and the positive impact on the design of a more simplified and efficient flotation flowsheet.