Capricorn Copper Mine (CCM) is an underground copper mining operation located 125 km northwest of Mt Isa in North West Queensland, Australia. The plant restarted operations in late 2017 after being in care and maintenance for a number of years. After plant start-up in early 2018, copper recovery was well below the study expectation. Plant data confirms that the copper recovery is affected by the proportion of pyrite in the ore. This led to an investigation being carried out that found a significant amount of liberated ultrafine copper sulphides in the tailings and liberated pyrite in the final concentrate which called attention to a recovery improvement opportunity.
A comprehensive investigation was completed in 2019; it consisted of a full plant survey followed by ToF-SIMS, mineralogy and size-by-size analysis of key streams. In addition, batch flotation test work were carried out testing various assumptions for the mode of copper losses into tailings. Plant surveys of pH, pulp potential (Eh), Dissolved Oxygen (DO) and EDTA extraction were also performed investigating the effect of pulp chemistry on metallurgical performance. This paper demonstrates the power of combining process mineralogy and surface chemistry analysis to optimise and troubleshoot flotation circuit performance. The results are discussed in terms of improving the copper sulphides recovery and depressing pyrite flotation.