Curis Resources unveils preliminary metallurgical results from Florence copper project

Curis Resources (TSE:CUV) unveiled late Thursday preliminary results from lab test work done on metallurgical samples taken from a summer 2011 drilling program at the company's Florence copper project in Arizona.
The company, which is focused on bringing its Florence project to production, started metallurgical testing in June of last year to confirm and improve on historical copper recovery estimates, it said.
Bottle roll testing was done on 16 initial samples from the 2011 drilling, with results comparing "favourably" to work completed by BHP Copper in the mid 1990s, Curis said.
Today, the company released results from the bottle roll tests, as well as four laboratory-scale in-situ copper recovery tests, with 12 in-situ tests still ongoing and expected to be completed in the second quarter.
"We are very pleased with the preliminary results from our extensive metallurgical test program which is being overseen by Dr. Terry McNulty. of T. P. McNulty and Associates, Inc. and Dr. Dave Dixon of the University of British Columbia," said Curis' VP of environment and technical services, Dan Johnson.
"The results of these tests indicate that there are significant opportunities to improve on historical estimates of copper recovery at Florence Copper and, ultimately, the overall positive economics of this project."
The bottle roll testing program saw sections of core taken from four summer 2011 drill holes, which were then selected to make up 16 samples, with four samples from each of the four holes. A total of 16 bottle roll tests were each run for 72 hours while maintaining constant acid concentrations.
On average, the acid-soluble copper head grades represented 68 percent of the total copper present, versus the 67 percent assumed in the six-year recovery model used for the preliminary economic assessment (PEA) in September 2010.
At the nominal concentration of 10 grams/liter (g/l) sulfuric acid for extraction testing purposes, the average acid-soluble copper extraction was 90 percent versus the 86 percent extraction that was assumed in the PEA and in BHP's prefeasibility study, Curis said.
Samples were also submitted for mineralogical characterization at Montana Tech of the University of Montana, which confirmed chrysocolla as the dominant copper mineral, also consistent with the PEA results.
Meanwhile, the in-situ recovery program was done to simulate in-situ treatment of the Florence copper resource by allowing recovery solutions to flow horizontally through intact pieces of drill core, using a special lab apparatus.
To date, four of 16 in-situ recovery tests have been completed with copper extraction ranging from 45 to 81 percent, as compared to a recovery of 49 percent reported in the PEA.
Of these, the tests that were run using 5 g/l sulfuric acid solution averaged 46 percent copper recovery, while the tests run at 10 g/l sulfuric acid averaged 71 percent copper recovery.
Curis said that historical in-situ lab simulations relied on columns that simulated vertical flow, rather than horizontal flow, and also did not keep the core intact without the use of stabilizing agents. The company said it therefore believes the current program is "much more representative" of actual in-ground conditions expected at the Florence project.
Terry McNulty, of TP McNulty and Associates, which is overseeing the metallurgical test program, said: "I believe that the ISR simulation protocol that has been developed by Curis and Metcon staff is the most realistic approach that has been taken to resolving this difficult technical challenge.
"The tests have proceeded smoothly and I feel very positive about the physical conditions of the leached core, the leaching kinetics, and the percentage of copper that dissolved during the leaching."