Carmax Mining Corp. ("Carmax") is pleased to announce results from preliminary grindability and flotation testing on Carmax Mining Corporation's Eaglehead copper-gold-molybdenum project, located in northwest British Columbia. Test work was completed by SGS Mineral Services ("SGS").
- All copper is present as copper sulphides - primarily as chalcopyrite with lesser amounts of bornite.
- The final copper/molybdenite bulk concentrate from lock cycle testing assayed 29.6% Cu, 2.72% Mo, 28.2 g/t Au, and 175.9 g/t Ag.
- Metal recoveries of 89.9% copper, 71.1% molybdenite, 78.6% gold, and 78.1% silver were achieved in locked cycle tests.
- Low concentrations of arsenic, selenium, and tin were recorded in the concentrate.
- Tests to upgrade molybdenum recovery in a separate molybdenum cleaner circuit were not completed.
Mr. Jevin Werbes, President of Carmax, stated, "We are very pleased with these results, which were an extension of the 2015 test work. Locked cycle tests produced a clean copper concentrate with significant by-product credits. As a result, SGS has recommended more analytical work focusing on a comprehensive testing program, including a significant number of locked cycle tests."
Summary of Test Work:
Four representative flotation samples, with weights ranging from 17.0 to 43.6 kg, were sent to SGS. Additionally, fifteen grindability samples, with weights ranging from 8.8 to 36.9 kg were also submitted.
A master composite was prepared from four sub-composites. Head assays of the major elements from the master composite and the four sub-composites are summarized below.
Head Assays of Master Composite and Sub-Composites
QEMSCAN analysis on the sub-composite samples show that chalcopyrite and bornite are the dominant copper sulphides, with low pyrite concentrations ranging from 0.03-0.17%. Gangue minerals include dominantly plagioclase and quartz along with sericite/muscovite, K-feldspar, and carbonates.
Bond Ball Mill Work Index (BWI) testing was performed on nine samples. The indices varied from 16.9 to 20.6 kWh/t, with an average of 18.6 kWh/t. Bond Abrasion Index (AI) testing was performed on six samples and indices ranged from 0.211 g to 0.554 g, with an average Ai of 0.381 g. These samples were categorized as hard and very hard with medium to abrasive Abrasion indices.
Locked Cycle Tests:
All samples responded well to conventional copper-molybdenite flotation. Test work employed four stages of roughing. This was followed by regrind and three stages of cleaning with a primary grind size K80 of approximately 150 μm and a regrind size K80 of 21 μm. The final copper/molybdenite bulk concentrate assayed 29.6% Cu, 2.72% Mo, 28.2 g/t Au, and 175.9 g/t Ag at recoveries of 89.9% copper, 71.1% molybdenite, 78.6% gold, and 78.1% silver.
SGS made the following recommendation for further test work on the copper mineralization:
- further copper-molybdenite separation and flotation optimization, investigating the effect of primary grind size on flotation
- copper-molybdenite separation testing to estimate the final molybdenite concentrate metallurgy (grade and recovery)
- flotation optimization, such as the effect of primary grind size.
Sample Preparation and Test Work Parameters:
The flotation samples were stage-crushed to -10 mesh, homogenized, rotary-split into 2 kg charges, and freezer-stored for test work.
The flotation test procedure involved grinding a 2 kg test charge at 65% solids in a laboratory ball mill to target grind size. After grinding, the density of the pulp was adjusted to 33% solids in a Denver D1 flotation cell. The collectors were then added, conditioned, and finally the frother added. Regrinding of the rougher concentrate for cleaner tests was conducted using ceramic grinding media in a ceramic mill. Cleaning was conducted using a 250 g cell using the same procedures. All products were filtered, dried, weighed, and assayed.
Flotation times were 14 minutes and four stages of rougher were employed for all tests. Initial grind calibrations were performed followed by rougher kinetic, batch cleaner and locked cycle tests.
Nine samples (samples weight ranged from 8.8 to 36.9 kg) were subjected to Bond Ball Mill Work Index (BWI) testing. Each sample was stage-crushed to -6 mesh and homogenized. The test was performed at 80 mesh of grind (180 μm). Six samples were subjected to Abrasion Index (Ai) testing. Each sample was stage-crushed to -3/4 inch and homogenized.
Chris M. Healey, P.Geo., a Director of Carmax, is a qualified person as defined in NI 43-101, and has reviewed and approved the technical information contained in this news release.
About The Eaglehead Project:
The Eaglehead property hosts an NI 43-101 Inferred Mineral Resource estimated to total 102.5 million tonnes at an average grade of 0.29% Cu, 0.010% Mo and 0.08 g/t Au. The NI-43-101 Technical Report was prepared by RPA Inc. (see Carmax news release dated May 16, 2012), by Barry McDonough, P.Geo., and David W. Rennie, P.Eng. both Qualified Persons. The report is filed on Sedar at www.sedar.com.