Copper recovery improvement in an industrial flotation circuit: A case study of Sarcheshmeh copper mine

Obtaining high recovery in copper flotation plants has been always under investigation in recent years. Misreported copper into tailing dramatically declines copper recovery. This study aims to find the possible reasons of copper loss to tailing and present the methods to improve the performance of the Sarcheshmeh copper plant flotation circuit. This work was performed in two phases. In the first stage, two surveys were carried out in an industrial plant for evaluation of floatability of two different types of copper ore (sulfide and mixed copper ores comprising sulfide and oxide minerals) and investigation of misreported copper into tailing. In the second stage, influence of particle size distribution in different levels, the collector (Z11 + R407), and sulfidisation agent (NaHS) dosages were investigated on the floatability of mixed copper ore, and possible improvement of copper recovery ores was evaluated by a series of batch flotation experiments.

Almost 95% of overall copper loss in final tailing took place in the rougher circuit. The overall recovery of mixed copper ores was obtained 8% less than the other survey. It was found that an important factor of recovery reduction was due to increasing oxide copper proportion in rougher feed. Results of size-by-size recovery analysis showed that the highest sulfide copper loss occurred in coarse particles (>74 µm) and the highest oxide copper loss happened in fine particles (<9 µm). From batch flotation experiments, it was found that the ultimate recovery increased to a certain value with increasing the collector dosage (50 g/t) and thereafter reduced. Increasing the NaHS dosage to 800 g/t resulted in 4.5% increase in recovery from 79.3% to 83.8% with a significant increase in grade. It is observed that size reduction of coarse particles (>74 μm) of rougher tailing and then their flotation have significant effect on increasing overall recovery from 79.3% to 82.2%. Experimental studies showed that the use of the proposed methods with considering the optimized conditions in the plant can be led to an increase in copper recovery from 79% to 87% without any decrease in grade.