Dec 4 2014
Copper Fox Metals Inc. and its wholly owned subsidiary Desert Fox Copper Inc. are pleased to announce the preliminary results of the in-situ leaching tests completed on samples of the oxide copper mineralization from the Van Dyke oxide copper project.
The main objective of the test work was to evaluate copper dissolution kinetics, total soluble copper extraction, acid consumption and to simulate the underground hydraulic pressure in an in-situ leaching process over a 120 day leach period.
Highlights:
- Calculated total copper grades ranged from 0.35% to 2.03% and averaged 0.76%,
- Approximately 89% of the copper contained in the samples reports as soluble copper,
- Gangue acid consumption ranged from 0.72 kg/kg copper to 23.69 kg/kg copper and averaged 7.72 kg/kg copper,
- Copper extractions ranged from approximately 87% to 24% and averaged 63%, and
- The relative difference between the percentage copper extractions and the percentage of soluble copper (acid soluble copper and cyanide soluble copper) reported could be due to lack of solution diffusion, lack of ferric iron generation, mass transfer or solution channeling in the test vessels used to complete the tests.
Mr. Stewart, President of Copper Fox stated, "We are pleased with the preliminary in-situ leach test work results for the Van Dyke oxide copper deposit. The high percentage of soluble copper in the test samples combined with the reported acid consumption is very encouraging and considered a significant milestone in the advancement of the project. These results combined with the resource estimation that is currently underway will be used to determine the next phase of work to be completed at the Van Dyke project."
Van Dyke Project:
The 1,100 acre Van Dyke project is located in the Globe-Miami Mining District, 90 miles east of Phoenix, Arizona. This district hosts the Pinto Valley, Carlota, Miami-East and Miami-Inspiration copper projects and the mined-out Copper Cities and Old Dominion copper deposits. The Van Dyke oxide copper deposit is located immediately adjacent to the Miami-East and Miami-Inspiration copper projects (see the Company's news release dated April 12, 2013 for further detail with respect to the historical work completed on the Van Dyke oxide copper deposit).
Moose Mountain Technical Services is working toward completion of a resource estimate on the Van Dyke oxide copper deposit. The estimate will incorporate results of the 2014 verification drilling program and those elements of the historical data base that are applicable (see the Company's news release dated October 28, 2014 for further details with respect to the resource estimate).
In-Situ Leach Results:
The In-Situ Copper Leaching Simulation Study (the "Study") was completed by SGS E&S Engineering Solutions Inc. ("SGS") located in Tucson, Arizona. The Study was completed on eight samples selected from five of the six confirmation diamond drill holes completed on the Van Dyke project in 2014. These samples were subjected to leaching under a nominal pressure of 120 pounds per square inch ("psi") to maintain carbonates in solution over 120 days of a locked cycle type of leaching regime to simulate the underground hydraulic pressure in the in-situ leaching process. The combination of acid soluble and cyanide soluble copper are used to determine the total soluble copper in the samples.
Sample PRT-03 yielded the lowest (approximately 24%) copper extraction of all samples tested. This sample returned the lowest solubility in sulfuric acid and the highest solubility in cyanide indicating that the main copper mineralization could be chalcocite and covellite. This sample also demonstrated the highest acid consumption of all samples tested. SGS suggests that ferric iron generation will be required for dissolving the cyanide soluble copper contained in this sample.
A mineralogical examination on the test samples showed that chrysocolla and malachite are the primary copper bearing minerals. Native copper, azurite and chalcocite are present in minor concentrations.
Recommendations:
SGS has recommended additional test work on samples from the Van Dyke project to evaluate:
- the effect of ferric iron addition on dissolution of the secondary copper mineralization (cyanide soluble copper), and
- the effect of the surfactant addition to modify the surface tension of the lixiviant which may help on the dissolution of the un-leachable soluble copper,
In-Situ Leach Test Work:
The samples of the oxide copper mineralization from the Van Dyke deposit were cut into 60 centimeter long sections, wrapped and inside a stainless steel vessel, sealed with paraffin wax and subjected to pressure leach testing. A 1,000 gram sub-sample of each sample was crushed and submitted for mineralogical examination. On completion of the 120 day leach cycle, each sample (referred to as residue) was dried, crushed and subjected to sequential copper analysis. The soluble copper in the residue combined with the copper extracted during the leach cycle were added to obtain the calculated head grade for each sample. The mineralogical examination was completed at the Center for Advanced Mineral and Metallurgical Processing of the University of Montana. The chemical analysis for all samples was completed by SGS using Induced Couple Plasma ("ICP").
Source: http://www.copperfoxmetals.com/