Curis Resources (TSE:CUV) has taken another step toward enhancing the value of its Florence copper project in Arizona with another round of large scale metallurgical test work that was completed in advance of the prefeasibility study for the asset.
The company said Tuesday that in-situ recovery tests 17-22 have now been completed, with copper extraction ranging from 51 to 90 per cent, and averaging 69 per cent.
When all the copper extraction results are incorporated with recent sweep efficiency modelling, Curis said that preliminary indications show overall copper recovery of about 70 percent from a typical mineralized block.
The September 2010 preliminary economic assessment on the project used an average total copper recovery rate of just 49 per cent, which means the property's economics stand to improve considerably.
Shares of Curis rose almost 3 per cent on the back of the news this morning, to 70 cents.
In October, the company released results from the first 16 in-situ tests, showing an average copper recovery rate of 61 per cent, with copper extraction from these prior tests ranging from 33 to 89 per cent.
In the 1-16 in-situ metallurgical test series, optimal copper test extractions of over 70 per cent were reached by using mid-range (10 g/l) H2SO4 concentrations, which is consistent with earlier test work by both the company and prior owner, BHP Copper.
"The results from this final set of metallurgical test work clearly demonstrate the potential for improved copper recovery rates at Florence Copper," said VP of technical services and environment for the company, Dan Johnson.
"Our objective now is to integrate these results into a new financial and engineering model for Florence Copper that is scheduled for release in Q1 2013 in the form of a pre-feasibility study (PFS)."
The goal of the ongoing in-situ recovery test program has been to represent a cross-section of the property through a typical mineralized block in the deposit, and to simulate in-situ treatment of the Florence ore body by allowing recovery solutions to flow horizontally through intact pieces of drill core assembled as a mineralized block.
The in-situ recovery process requires no movement of rock or overburden, and there is therefore a substantially smaller footprint, with much less of an environmental impact on the surrounding area than with more traditional open pit mining operations.
The technique also requires substantially less mechanical energy in the form of trucks and explosives, and therefore generates significantly lower operating and capital costs.
"Improved copper recoveries, combined with a revised mineral extraction plan and updated capital and operating cost estimates, are expected to further confirm Florence Copper as having the potential to be one the lowest cost near term copper producers in the world," continued Johnson.
Metallurgical testing to improve copper recovery began in June 2011 at Florence. The laboratory scale tests were based on samples taken from a core drilling program in 2011.
For every percentage increase of copper recovery, higher revenues stand to be generated from the project, which now has an estimated after-tax net present value of $360 million at a 7.5 per cent discount rate and a $2.50 per pound copper price.
The company in late September received the Aquifer Protection Permit from the State of Arizona's Department of Environmental Quality (ADEQ), which applies to the design, operation and closure of its phase 1 operations at the site.
The permit received authorizes the construction, operation and closure of a 24-well in-situ copper recovery operation - phase 1 - at the project in Florence, Arizona.
The recovery operation will be accompanied by an art solvent extraction/electrowinning facility that is designed to produce 99.999% pure copper cathode sheets, Curis said.
According to the latest timeline, the company could begin full commercial production by early 2015, after which it expects to produce between 55 and 84 million pounds of copper per year.
Dr. Terry McNulty, the metallurgical expert overseeing the in-situ tests for the company, added: "I continue to believe that the laboratory technique being employed by Metcon is much more realistic than earlier methods of projecting non-sulfide copper extraction by in-situ leaching.
"Also, ongoing mineralogical characterization of leached residues is improving our understanding of the behavior of host rock constituents and copper minerals during these tests."v
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