Meteoric Resources NL (ASX:MEI) has confirmed gold recoveries above 96% in recent metallurgical test-work on Butchers Creek deposit, the centrepiece of the wholly-owned Palm Springs Project in Western Australia.
This work was designed as a series of sighter tests to gauge the complexity required to recover gold from Butchers Creek using standard sulphide ore screening techniques.
The most encouraging result was obtained from the 'whole of ore' leach tests, which produced a recovery of 96.4% after a leach time of only 24 hours.
Promisingly, the Butchers Creek ore is deemed amenable to a low-cost processing route incorporating a standard CIL cyanide leach plant.
“Outstanding result”
Meteoric managing director Dr Andrew Tunks said: “These initial metallurgical test results of Composite #1 from Butchers Creek have produced an outstanding result in that a low-cost simple 'whole of ore' flowsheet using CIL only is indicated as being suitable for our project.
“Excellent cyanide leach recoveries in excess of 96%, with the potential to improve on this result, were achieved without the added complication, capital and operating cost imposed by either gravity recovery or flotation.
"The most important outcome from this test-work is the high leach recovery achieved on straight 'whole of ore' leaching, which indicates the gold is well liberated and not locked up or influenced by the presence of moderate amounts of sulphides.
“Such a high recovery number will feed directly into the current scoping study and will have a substantial impact on mine design and capital and operating cost estimates. The outcomes from the scoping study will drive the xompany’s Halls Creek strategy in 2022 and will be released in the first quarter of 2022."
Metallurgical test program
At the outset, each composite was formulated at ALS Laboratories in Perth from half HQ core sent from site and all test-work was done under the supervision of Trinol Pty Ltd in Perth.
Prior to compositing, half-core samples were set aside to measure the physical characteristics - UCS, Crushing Index (CWi) and Ball Milling Index (BBMi).
After that, head samples were examined by XRD to gauge the extent of sulphide minerals present, then subjected to the following standard test regime:
- Grind establishment;
- Gravity followed by direct cyanide leach;
- Gravity recovery followed by flotation, ultra-fine grinding to 10 microns of the concentrate and leaching of the tailings; and
- Whole of ore leaching.
Composite properties
The XRD analyses for Composite #1 confirms moderately sulphidic ore containing just over 1% combined sulphides.
In addition, the ore also contains calcite and carbonate, ~4% by mass, which will assist with moderating potentially acid-forming properties of the tailings and reduce lime consumption in the process.
Notably, the composited sample exhibited straightforward non-refractory metallurgical characteristics.
The measured physical properties indicated a weak to moderate hardness for the ore which would not pose issues in terms of the design or selection of conventional crushing and grinding equipment.
Forward plan
Composite #2 test-work is being completed at ALS and the results are expected next month.
These results will be incorporated with Composite test #1 and fed into the scoping study that is underway with independent consultants, Auralia Mining Consulting. Results from the studies will be available in the March quarter of 2022.
From these results, a simplified flowsheet presents a potential low-cost treatment facility and ore which is amenable to toll treatment.