JOHANNESBURG (miningweekly.com) - JSE- and ASX-listed minerals exploration company Orion Minerals has successfully completed the development of a mineral flowsheet for the treatment of sulphide zinc/copper mineralisation at the Prieska project, in the Northern Cape.
The derived mineral processing flowsheet achieves high zinc and copper recoveries into separated product streams from which the production of high-quality, differentiated zinc and copper concentrates can be yielded.
The company on Thursday said in a release that the processing flowsheet has been tested with notable success on all the mineralised zones of the Prieska deposit that are targeted in the bankable feasibility study (BFS) that is under way.
The deposit is zoned for metallurgical testing by the degree of oxidation (shallow supergene and deep hypogene zones), while the internal variation in zinc and copper grades relative to each other across the deposit was also considered (zinc-dominant and copper-dominant zones).
Representative core samples for the testwork were collected from holes drilled by Orion across these different grade and oxidation zones, as noted in a release in November last year.
Most significantly, effective zinc and copper separation has now been achieved from samples collected within the supergene horizon of the deposit, while maintaining acceptable metal yields from both the copper and zinc circuits for differentiated concentrates.
This, the company commented, is a notable improvement on the metallurgical performance achieved by historical mining operations and from earlier testwork.
Results of the successful completion of Phase 1 were reported in November 2017, confirming that the targeted mineralisation at the Prieska deposit was amenable to processing by froth flotation.
The results achieved from Phase 2 testwork, reported on Thursday, are indicative of how the derived flowsheet performs with respect to recovering and separating targeted metals, the company said.
However, ongoing optimisation aims to improve the resultant concentrate qualities to equal or better the metallurgical performance that was reported to have been achieved during historical mining operations.
Over the 20-year mine life, metal recoveries averaged 85% for both zinc and copper into concentrates that had concentrate grades ranging between 28% to 30% for copper (in the copper concentrates) and 51% to 53% for zinc (in the zinc concentrates).
The company further elaborated that the metallurgical testwork results achieved to date confirm that the Prieska deposit is amenable to efficient treatment applying widely-used, well-understood mineral processing techniques and using standard, widely available reagents.
"The Phase 2 metallurgical testwork results have yet again met all our expectations and are an important advance within the BFS studies. The importance of achieving effective metal separation as a precursor to locked cycle testwork to optimise concentrate qualities is significant. The suitability of the openpit supergene target to the same process routes and concentrate sales strategies is particularly important," said Orion MD and CEO Errol Smart.