Characterization of an industrial flotation column at division Andina, Codelco-Chile

The copper cleaner flotation circuit at Divisiَn Andina Codelco-Chile consists of two rectangular flotation columns, 2x65m in side and 14 m height, operating in parallel. The columns have a distinctive characteristic because they operate at very high superficial air rate (3 cm/s) and wash water rate (0.5 cm/s). Under these extreme conditions a minimum froth depth of 100 cm was required to achieve the target copper grade (30%). The observation of the froth zone as a distributed system, by measurement of grade profiles of copper and insolubles, clearly showed the significant impact the froth depth has upon the froth internal contamination. At a shallow froth depth, 60 cm, the froth became almost fully contaminated with insolubles. In all cases the pulp/froth interface becomes diffuse. Experience with tracer tests showed that despite the high superficial air rate, no entrainment of pulp water into the concentrate was observed, because of the strong addition of wash water. Finally, the column optimal working zone was explored in terms of the main manipulated variables. It was found that by keeping a proper ratio between the superficial gas and wash water rates, it was possible to decrease the consumption of air and wash water by almost a half, for the same concentrate copper grade and recovery.