Vancouver, October 23, 2018 – John Cumming, President and Chief Executive Officer of Stellar AfricaGold Inc., (TSX-V: SPX) (“Stellar” or the “Company”) announces:
Balandougou Gravity Mill Bulk Sampling Update
Notwithstanding the recent upgrades and adjustments to the Balandougou gravity mill and concentrators the gold recovery remained below expectations with daily gold recoveries in the 0.2 to 0.3 g/p/t range with only a few exceptional days in the 1.0 to 2.25 g/p/t range.
The original metallurgical bench tests conducted by SGS South Africa concluded that a 66% gold recovery over four-stages of gravity separation was possible. Those tests were under optimal laboratory conditions and Stellar’s Balandougou gold mill has not been able to replicate those rates of recovery with larger scale commercial equipment.
After resuming bulk sample milling operations in September, the Company conducted a systematic sampling program to evaluate the post-upgrade operating efficiency of the gravity mill. Input grades were determined by sampling all loads of mineralized material dumped into the mill, and time-scheduled samples of the rejects from the Knelson concentrators were taken. This sampling program was conducted over several days to obtain a sufficiently large number of samples to provide an accurate representative average grade of the processed material.
This sampling program revealed that during the time of the feed grade monitoring exercise the input grade of the processed material was an average of 2.0 g/p/t gold. At the tailings end, for the same period, the material rejected from the concentrators was sampled every 30 minutes and the average grade of those tailings was 1.73 g/p/t gold. Overall, only approximately 10 to 20% of the 2.0 g/p/t gold within the feed material was recovered during the milling and concentrating process with approximately 80-90% of the gold remaining in the concentrators’ tailings. Additionally, from beginning of the gravity test operation, the tailings were periodically visually inspected by experienced local gold workers and no significant gold was detected. Comparing the Balandougou gold mill operating results with the original SGS Screening and Grading analysis, the conclusion is that the gravity plant is recovering only gold grains larger than 300 microns (0.3 millimeter) representing only approximately 20% of all the gold contained in the B3 zone material and that the high recovery days were the results of processing pockets of high-grade course gold mineralization.
Consequently, milling operations have been temporarily shut down while the Company undertakes further metallurgical analysis of the Balandougou mill feed; however, the preliminary conclusions are that the grade of the gold mineralization processed from the B3 Zone is, as was anticipated, approximately2.0 g/p/t and that a large percentage of the gold grains are too fine to be captured by gravity methods on a large scale operation. The Company is currently considering the viability and economics of various alternatives for adding a cyanide recovery circuit to the existing mill which could increase gold recovery to approximately 96% as was reported by SGS South Africa in its 2016 report on cyanidation testing of the tailings of the gravity tests.
