Curis extracts up to 89% copper from Florence 2012-10-11 08:37 ET - News Release
Mr. Michael McPhie reports
CURIS REPORTS UPDATED COPPER RECOVERY RESULTS AT FLORENCE COPPER
Curis Resources Ltd. has released updated results for laboratory testwork performed on metallurgical samples from the Florence copper property in Arizona.
Highlights of these in situ recovery (ISR) tests include the following:
- Sixteen ISR tests have been completed, with copper extraction ranging from 33 per cent to 89 per cent and an average copper extraction of over 61 per cent.
- Optimal copper test extractions of over 70 per cent were achieved by using mid-range (10 grams per litre) sulphuric acid (H2SO4) concentrations, consistent with earlier testwork by both Curis and BHP Copper.
The economic model presented in the September, 2010, preliminary economic assessment (PEA) for the Florence copper project used average total copper recoveries of 49 per cent.
"We are very pleased with the outcome of this next phase of critically important metallurgical testwork at Florence Copper," stated Dan Johnson, vice-president, technical services and environment, Curis. "These results further confirm that there is tremendous potential to improve on the copper recoveries from historical estimates, and on the overall robust economics indicated in the PEA for this world-class in situ copper recovery project."
The goal of the continuing ISR test program is to represent a cross-section through a typical mineralized block in the deposit, and simulate in situ treatment of the Florence mineralized resource by allowing recovery solutions to flow horizontally through intact pieces of drill core using a specially designed laboratory apparatus. The test program was designed by metallurgical specialist Dr. Terry McNulty.
Dr. McNulty stated: "I remain convinced that the core box approach toward ISR simulation is more realistic than the vertical column method that has been used in the past, and that it will enable a reliable projection of well field performance."
The next step in the metallurgical testing program will be to have these results incorporated into an overall assessment of predicted ultimate copper recoveries.
Background
Metallurgical testing to confirm and improve on historical copper recovery estimates for the Florence copper project began in June, 2011, at Metcon Research of Tucson, Ariz. Bottle-roll test results on 16 initial samples from a 2011 core drilling program, along with laboratory-scale ISR test results for four of these samples, were reported in a Curis press release dated Feb. 23, 2012. The results compared favourably with work completed by BHP Copper in the mid-1990s, as summarized in Curis's September, 2010, PEA. Test results for the remaining 12 ISR tests have now been received and are summarized herein along with the four ISR tests that were reported earlier.
Detailed ISR test results
The accompanying table provides details from the 16 ISR samples tested.
ISR LABORATORY TEST RESULTS Feed Leach Rinse Calculated CumulativeTest No. H2SO4 cycle cycle head assay extraction (g/L) (days) (days) (% Cu) (% Cu)Box 1 5 152 43 0.46 47.47Box 5 5 158 38 1.22 44.76Box 9 5 186 46 0.77 63.51Box 13 5 176 37 0.26 32.94Box 2 10 151 77 1.00 88.72Box 3 10 152 43 0.58 81.32Box 6 10 151 77 0.32 71.68Box 7 10 154 42 0.52 59.79Box 10 10 134 78 0.36 63.54Box 11 10 186 46 0.87 84.26Box 14 10 134 78 0.42 47.79Box 15 10 219 8 0.44 68.48Box 4 20 152 78 0.49 34.74Box 8 20 154 78 0.74 77.01Box 12 20 176 37 0.45 48.30Box 16 20 218 8 0.17 66.95
"These results suggest a mid-range sulphuric acid feed of between eight to 10 grams per litre is likely to be optimal for the Florence copper project to achieve maximum possible recoveries," commented Mr. Johnson.
ISR TEST RESULTS BY H2SO4 CONCENTRATIONAverage feed H2SO4 Average extraction(g/L) (% Cu)5 47.1710 70.7020 56.75
The metallurgical test program is being supervised by Dr. Terry McNulty, PE, of T.P. McNulty and Associates Inc. of Tucson, Ariz., who is a qualified person as defined in National Instrument 43-101 and has reviewed this disclosure.