QMines Limited announced the results of its updated metallurgical testwork from its Mt Chalmers copper and gold project. Mt Chalmers is the Company's project, located 17km north-east of Rockhampton in Queensland. This study was undertaken by Mark Hargreaves, a senior Process Engineer from Como Engineers in Western Australia (Como).

The testwork was designed to maximise gold recovery whilst achieving a grind and reagent regime suitable to produce a clean copper concentrate (containing gold and silver). It was also designed to upgrade the copper float tail to one or more saleable concentrates containing zinc, lead, gold and silver. These results build on earlier testwork, announced in March 2022¹, which established a preliminary flowsheet and determined working recovery grades for stringer and massive sulphide concentrates from Mt Chalmers.

Ongoing metallurgical testwork is being undertaken to progress a Feasibility Study on the Mt Chalmers deposit and deliver a maiden Ore Reserve statement. The Mt Chalmers mineralisation comprises a stringer zone (Cu-Au) and a massive sulphide (Cu- Pb-Zn-Au-Ag) zone. Metallurgical testwork on the stringer zone, the dominant mineralisation style, is almost complete with only further grind testing to be completed.

Further testwork is planned for the massive sulphide mineralisation which aims to maximise recoveries of all marketable metals. Half drillcore samples from drill hole MCDD017 have been used in the study, together with new material from drillhole MCDD044, as the former material becomes depleted. The objectives of the testwork was to maximise gold recovery into a flotation product, achieve a reagent regime suitable to produce copper concentrates containing gold and either a combined lead and zinc concentrate or separate lead and zinc concentrates, while maximising sulphide recovery.

Initial testwork of the stringer mineralisation, from a half core composite sample from drill hole MCDD017, produced a 12.3% copper concentrate with 97% recovery. This updated trestwork on grind size and laboratory flotation method has produced considerably better grades including 23% copper in concentrate with 98% recovery. Each of the tests produced a potentially marketable copper product with significant gold credits.

The lead, zinc and silver grade in the stringer composite were low and were thus excluded from the flowsheet to simplify the circuit. A coarse grind of 150 microns produced an 87% copper recovery and a 64% gold recovery while a finer grind of 75 microns produced 96-98% copper recovery and 60-82% gold recovery. Additional tests on an intermediate grind size of 106 microns will seek to increase the minimum copper recovery to above 90%, in order to maximise copper and gold recovery at the coarsest grind size possible.