Orion Prieska
Orion Minerals' Prieska copper zinc project

ASX-listed Orion Minerals announced that the development of a mineral processing flowsheet, for treatment of sulphide zinc-copper mineralisation at the Prieska zinc copper project has been successfully completed.

South Africa –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 processing flowsheet has been tested with notable success on all the mineralised zones of the Prieska project deposit that are targeted in the Bankable Feasibility Study (BFS) currently underway.

The deposit is zoned for metallurgical testing, by the degree of oxidation.

The internal variation in zinc and copper grades relative to each other across the deposit was also considered.

Representative core samples for the test work were collected from holes drilled by Orion Minerals across these different grade and oxidation zones.

Most significantly, effective zinc and copper separation has now been achieved from samples collected within the supergene horizon of the deposit, whilst maintaining acceptable metal yields from both the copper and zinc circuits for differentiated concentrates.

This is a notable improvement on the metallurgical performance achieved by historical mining operations and from earlier test work.

The derived flowsheet, when applied to samples collected from the supergene horizon, achieved maximum metal recoveries of 88% zinc within the zinc circuit and 74% copper within the copper circuit.

Samples collected from the hypogene horizon attained maximum metal recoveries of 85% for zinc within the zinc circuit and 88% for copper within copper circuit.

These metal recoveries, were achieved using only open-circuit testing, and compare very well to metal recoveries reported to have been achieved during historical mining operations1.

Further improvements in metal recovery and the production of optimised, premium quality concentrates can be expected during the follow-up locked-cycle testing that is currently underway.

Locked-cycle testing better simulates the continuous operating conditions of a mineral processing plant and so more accurately defines design metal recoveries and metal concentrate qualities.

Locked-cycle test results will form the basis of assumptions to be incorporated into the BFS which is targeted for completion in Q4 2018.

Metallurgical Test Work Approach

Metallurgical studies on Orion Minerals’ Prieska project deposit are being conducted in three defined phases as part of the BFS, these being:

Phase 1– flotation amenability scouting: to determine whether froth flotation is a mineral processing technique that can continue to be used to recover and concentrate zinc and copper sulphides from the dip and strike extensions of the Prieska deposit that is targeted for future mining;

Phase 2 – flowsheet development: to derive a froth flotation-based processing route, able to produce separated zinc and copper concentrates, within targeted quality ranges and achieve high metal recoveries from all metallurgical zones of the deposit, including open pitable supergene sulphides and;

Phase 3 – optimisation and detailed design: being the final stage of metallurgical design, which aims to optimise, validate and then conclude a detailed design of the ore processing plant, to enable production scheduling and accurate costing.