Mr. Michael McPhie reports
CURIS UPDATES METALLURGICAL RECOVERY TEST WORK AT FLORENCE COPPER
Curis Resources Ltd. has released the results for recently completed continuing
large-scale metallurgical testwork in advance of finalization of the
prefeasibility study on its 100-per-cent-owned Florence copper project in
Arizona.
Highlights of the in situ recovery (ISR) test results shown in the table include the following:
- ISR tests 17 to 22 have now been completed with copper extraction ranging
from 51 per cent to 90 per cent. All tests in this most recent series were run as previously described in
the Curis press release dated Oct. 11, 2012.
- When all the copper extraction results are incorporated with recent
sweep efficiency modelling, preliminary indications are that overall copper recovery of approximately 70 per cent will be achieved from a
typical mineralized block.
"The results from this final set of metallurgical testwork clearly
demonstrate the potential for improved copper recovery rates at
Florence copper," stated Dan Johnson, vice-president of technical services and environment
with Curis. "Our objective now is to integrate these results into a new financial and
engineering model for Florence copper that is scheduled for release in
first quarter 2013 in the form of a prefeasibility study (PFS). 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. We are very happy with the results of our work over the past year in
refining our development plans and confirming our engineering
assumptions for Florence copper."
Background
Averaging 69-per-cent copper extraction, the ISR test 17 to 22 series
results compare favourably with the 70-per-cent average extraction rates
previously reported for boxes within the ISR test one to 16 series (see
Curis press release on Oct. 11, 2012). The economic model presented
in the September, 2010, preliminary economic assessment (PEA) for the
Florence copper project utilized an average total copper recovery of 49
per cent.
The next step in the metallurgical testing program is to incorporate
these results into an overall assessment of predicted ultimate copper
recoveries for inclusion in the prefeasibility study which is expected
to be released in first quarter 2013.
The goal of the continuing ISR test program has been to represent a
cross-section through a typical mineralized block in the deposit and
to simulate in situ treatment of the Florence copper orebody by
allowing recovery solutions to flow horizontally through intact pieces
of drill core assembled as a mineralized block using a specially
designed laboratory apparatus. This successful physical simulation and
test program was designed by Curis and Metcon Laboratories of Tucson,
Ariz., with oversight and direction from acknowledged world
metallurgical expert, Dr. Terry McNulty.
Dr. McNulty stated: "I continue to believe that the laboratory technique being employed by
Metcon is much more realistic than earlier methods of projecting
non-sulphide copper extraction by in situ leaching. Also, ongoing
mineralogical characterization of leached residues is improving our
understanding of the behaviour of host rock constituents and copper
minerals during these tests."
Metallurgical testing to confirm and improve on historical copper
recovery estimates for the Florence copper property began in June, 2011,
at Metcon. Bottle roll and laboratory-scale ISR test results on 16
initial samples from a 2011 core drilling program were reported in
previous Curis press releases dated Feb. 23 and Oct. 11, 2012.
The results compared favourably with work completed by BHP Copper in the mid-1990s, as summarized in Curis's September, 2010, PEA.
Laboratory-scale ISR test results for six additional samples from the
2011 core drilling program have now been received and are summarized
in the table.
Detailed in situ recovery test results
The table provides details from ISR tests 17 to 22.
ISR LABORATORY TEST RESULTS FOR BOXES 17 TO 22
Test Calculated Cumulative
head assay extraction
(% Cu) (% Cu)
Box 17 0.44 62.58
Box 18 0.25 51.26
Box 19 0.36 70.45
Box 20 0.44 57.96
Box 21 0.59 90.46
Box 22 0.49 80.88
The metallurgical test program is being supervised by Dr. Terry McNulty,
PE, of TP McNulty and Associates Inc. of Tucson, Ariz., qualified person as defined by National Instrument 43-101, who has reviewed this
disclosure.
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