Apr 12 2017
GMV Minerals Inc. is pleased to announce the results of its large scale (1 metre in diameter by 6 metres in height column) testing of material from a low-grade portion of the Mexican Hat gold resource. The test was designed to estimate gold recoveries from marginal-grade mineralization at Mexican Hat and its suitability for potential Run of Mine (ROM) heap leach processing.
Results from screening analysis confirmed gold mineralization is generally confined to fracture planes. Thus, more heavily fractured rock within the gold zone carries higher grades and the rock will preferentially break along these fractures. Unfractured rock does not contain significant gold values, and is not as friable as the more heavily fractured, higher grade, sections of the gold zones. As a result, there is a strong positive correlation between gold grades and particle size, with the coarser material being significantly lower grade than the finer particles. Feed to the column graded 0.282 grams of gold per tonne (reconciled grades). Feed coarser than 2" represented 33.4% of the total mass tested, yet contained only 20% of the gold. Material finer than 2" represented 66.6% of the feed and contained 80% of the gold. The minus 2-inch material had a calculated head grade of 0.34 gpt gold and yielded 78% recovery of the gold. The plus 2-inch material had a calculated head grade of 0.17 gpt gold (less than cut-off grade) and yielded a 39% gold recovery for an overall recovery of 70% on 0.28 gpt feed.
Ian Klassen, President of the Company reported, "These gold recoveries of 78% for our minus 2-inch low-grade mineralization confirms ROM leaching would be a viable recovery process. It is also of great importance that no clay or refractory issues were observed during testing. Previous testing of 2.4 tonnes of higher-grade material (crushed to 2 inches) at 0.5 gpt and 1.5 gpt returned 91.6% and 96.6% recoveries on the minus 3/4-inch component after 90 days and 80-90% overall recovery. It is very encouraging that the mineralization can be upgraded significantly simply by size and thereby offers potential for upgrading gold recovery in a mining scenario simply by concentrating the blast matrix. Further testing will be carried out to optimize metallurgical recoveries with a low-cost flowsheet as we continue to add tonnage and ounces by drill testing the Mexican Hat."
Mr. John Fox, P. Eng., the Company's metallurgist reported, "these results together with more comprehensive bottle roll testing have confirmed that no significant differences or issues exist from all known mineralized rock-types from the property. This demonstrates substantial potential for a low cost ROM or ROM plus screening and single stage crush operation for the property. The results are materially better than average results for ROM testing, when compared to currently operating open pit heap leach operations in the world, thus confirming that this low-cost recovery method presents a viable option for the gold recovery of the deposit's lower-grade material."
These test results are from a 20-tonne sample of low grade mineralization from Mexican Hat. The Company tested 7.0 tonnes in the 6m column at nominal minus 6-inch crush to determine ROM heap leach potential in a 135 day leach.
Recovery curves reveal better leach results from finer-grained material with the minus 2-inch material grading twice that of the plus 2-inch material. Bottle roll testing of different mineralized rock types run during this program also confirmed excellent gold recoveries from all units identified on the property at all sample depths. Column testing was consistent, confirming 80% plus recoveries in all units with an appropriate crush with no apparent clay or refractory issues.
Cyanide and lime consumption was 0.46 kg/t and 1.61 kg/t respectively after 135 days of leaching.
All testing was conducted at Bureau Veritas Laboratories in Richmond, BC under the supervision of Dr. A. Shi and Mr. John Fox. Mr. John Fox, P.Eng. is the Q.P. for this release within the meaning of NI43-101 and has reviewed the technical content of this release and has approved its content.
Five drill holes on the Hernandez Hill epithermal target intersected weak to moderate silicification in four areas. Three of these holes confirmed elevated to very elevated gold pathfinder elements including silver and gold, however no economic values were obtained. The target remains highly prospective and further exploration is planned.
Lastly, pursuant to GMV's recently completed winter RC drill program, the Company is in the midst of modeling the results to determine: (a) how this will further enhance a revised resource calculation and NI43-101 expected later this year, and (b) assist the Company in the next phase of drilling to futher expand the known gold resource at the Mexican Hat. The Company is now permitting this next phase of drilling.
Source: https://www.gmvminerals.com/news/2017/gmv-minerals-inc-reports-excellent-gold-recoveries-on-large-scale-metallurgical-tests-confirms-rom-positive-potential/