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
"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
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
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.
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
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."