Pinnacle Silver and Gold Corp (TSX.V PINN, OTC: PSGCF) has released results from the preliminary scoping metallurgical tests for the high-grade El Potrero gold-silver project in Durango, Mexico.
Among the highlights from these results were gold recoveries running up to 96.79% and averaging 95.09%.
Three samples from the mineralized zone in the Pinos Cuates underground mine were sent to the SGS Lab in Durango, Mexico for grinding, bottle roll cyanide leach and gravity tests.
Initial grind calibration tests in a ball milling application achieved a target grind of 80% passing 270 mesh, or 53 micron, particle size.
The bottle roll cyanide leach tests resulted in consistently high gold recoveries of 92.81%, 95.68% and 96.79%, albeit that silver recoveries were lower and more variable, at 41.41%, 73.53% and 49.11%, with an average of 54.68%.
This indicates the presence of a complex mineralogy and a need for further test work, perhaps to encompass extended leach times.
Reagent consumption was within expected ranges for a preliminary test.
“We are very pleased with the results from this preliminary round of metallurgical tests, especially for gold recoveries, and considering that there were only three samples from one of the three historic mines,” said Robert Archer, Pinnacle’s chief executive.
“These tests were run using simple baseline parameters and without any optimization. The results indicate that we need to conduct mineralogical tests on the mineralization to determine the nature of the gold and silver occurrences. While it is likely that gold occurs either as free particles or in electrum, silver can occur in electrum, silver sulphides or silver sulphosalts. Once this has been established, further testing will be able to fine tune the metallurgical processes in order to increase recoveries, particularly for silver. Metallurgical testing is an iterative process, and it is expected that sampling of the other mines on the property will result in further variations. However, this is the whole point of the testing as we aim to maximize recoveries and streamline the flow sheet prior to rebuilding the plant.”
View from Vox
With gold still running at higher than US$3,900 an ounce, it’s not a bad time to be telling the market about excellent gold recoveries. That Pinnacle ought to be able to get the silver recoveries up too, in due time, is also worthy of note. The ore at El Potrero begins to look very attractive. The key questions to follow up on now are: how much of it is there, and how much will it cost to get it out of the ground? Drilling will take us close to the answers.