La Mancha's VMS Project Returns Promising Metallurgical Test Results
April 08 2010 - 6:33AM
Marketwired Canada
La Mancha Resources Inc. (TSX:LMA)
HIGHLIGHTS
-- 73% gold recovery and 87% copper recovery from the supergene material
-- 38% gold recovery and 85% copper recovery from the primary material
La Mancha Resources Inc. (TSX:LMA) (hereinafter "La Mancha" or the "Company") is
pleased to report that metallurgical test work conducted on samples from its
2008-2009 Volcanogenic Massive Sulfide ("VMS") exploration program at the Hassai
pit on its Hassai property in Northeast Sudan suggests that the supergene and
primary zone materials respond well to flotation and produce high-grade
concentrates. Results from the Hadal Awatib composite are not yet available.
In preparation for the upcoming Preliminary Economic Assessment ("PEA") for the
VMS project, La Mancha retained the services of SGS Canada Inc. of Lakefield,
Ontario, Canada ("SGS") to conduct Bench Scale and Locked-Cycle Flotation test
work, and mandated AMEC Minproc to prepare the PEA based on the metallurgical
test work results.
Table 1, as shown below, highlights the initial results for SGS's metallurgical
test work. Due to the different Hassai pit material, a Supergene composite
(based on the copper-enriched zone) and a Primary composite (based on the bulk
of the resource) were developed from samples sent to SGS in May, 2009.
Table 1:
---------------------------------------------------------------------------
Final Concentrate Final Concentrate
Hassai pit samples Head Grade Grade Recovery
---------------------------------------------------------------------------
Cu, % Au, g/t Cu, % Au, g/t Cu, % Au, %
---------------------------------------------------------------------------
Supergene composite 7.31 7.26 30.2 25.1 87.3 73.1
---------------------------------------------------------------------------
Primary composite 1.90 1.95 25.1 11.6 84.9 38.3
---------------------------------------------------------------------------
The flotation test work shows good metal recoveries, creating a saleable copper
concentrate. Additional test work was performed on the flotation tailings to
enhance gold recovery. The results were very positive, giving overall gold
recovery (including the copper concentrate above) of 92% for the Hassai pit
Supergene composite and 75% for the Hassai pit Primary composite. Further
analyses are currently underway to see if this process can be economically
achieved. More details on the mineralogy, flotation test work and gold
extraction from flotation tailings tests performed by SGS are provided in the
Technical Note section.
Although it is too early to draw any conclusions from these results and the
impact they will have on the outcome of the PEA, Dominique Delorme, President
and CEO of La Mancha, stated that he was very pleased: "The 48 million tonnes
43-101 inferred resource estimate announced in September and November 2009 had
already established that our VMS resource was of an impressive size.(1) Today,
we have taken another step in the right direction, with metallurgical test
results suggesting that the material responds favorably to traditional copper
flotation concentration and gold leaching processes. Copper concentration to
over 25% copper at a copper recovery rate of up to 90% is very encouraging."
(1) On November 4th, 2009, the Company announced a first 43-101 inferred
resource estimate for the VMS project of 48.48 million tonnes at an average
grade of 1.33 g/t Au and 1.23% Cu representing 2.08 million ounces of gold (0.83
million ounces attributable to La Mancha) and 576,000 tonnes of copper (230,400
tonnes attributable to La Mancha).
In preparing the PEA for La Mancha's VMS project, AMEC Minproc used the
metallurgical test work results to develop assumptions on the recovery rates to
be expected for gold and copper in the various parts of both deposits. The test
results were adapted to the resource grades and applied to the concentrator mass
balance model being used for the PEA. Based on the currently understood material
variability, three types are expected for the concentrator feed: Hassai South
Supergene, Hassai South Primary and Hadal Awatib. Tests have not been conducted
on Hadal Awatib, but the mineralogy is expected to be similar. Test results have
been extrapolated to the three material types, and then modeled to give
concentrate grades and metal recoveries as shown below in Table 2. Metal
recovery assumptions in Table 2 vary compared to the Locked-Cycle test-work
results in Table 1. Material grade differences and batch flotation test results
were considered by AMEC Minproc when making the assumptions.
Estimated results for flotation concentration are shown for three material types
defined in the Inferred resource announced on November 4, 2009:
Table 2: AMEC Minproc Flotation Concentration Estimation Results
---------------------------------------------------------------------------
Material average Concentrate Final Concentrate
grade grades Recovery
---------------------------------------------------------------------------
Cu, % Au, g/t Cu, % Au, g/t Cu, % Au, %
---------------------------------------------------------------------------
Hassai Supergene 2.75% 2.29 32% 22.0 81% 67%
---------------------------------------------------------------------------
Hassai Primary 1.37% 1.49 25% 11.0 90% 36%
---------------------------------------------------------------------------
Hadal Awatib 0.99% 1.18 25% 10.0 85% 29%
---------------------------------------------------------------------------
Bill Plyley, COO of La Mancha Resources, commented: "The assumptions in Table 2
that will form the basis for the copper concentrator design in the upcoming PEA
compare favorably with similar VMS projects. Test work by SGS on leaching the
tailings from the concentrator to recover additional gold was also encouraging
and, while it was not included in these assumptions, it could further improve
the gold recovery."
An initial review of the VMS resource suggested treatment by conventional
flotation concentration followed by cyanide leaching (CIL) of the tailing
products to increase gold recovery. Production of a copper concentrate (also
containing gold) to be sold to a secondary processor was envisioned. In
addition, concentrator tailings were expected to be leached to produce gold
bullion from a conventional CIL plant. Test work results to date confirm these
hypotheses.
NEXT STEPS
Over the next two months, the Company will continue to assist AMEC Minproc in
the preparation of a PEA for the Hassai VMS project. Results of this PEA are now
expected at the beginning of the third quarter. The main objective of this PEA
is to provide a first look at the economic viability of a VMS project at the
Hassai property on the basis of a series of assumptions that include operating
and development costs, and to provide a recommendation for the future of the
project.
TECHNICAL NOTE
Mineralogy
A sub-sample of the Hassai Supergene composite and Primary composite, at a grind
size of 80% passing 100 micrometers, was submitted for high-definition
mineralogical characterization. The predominant sulfide minerals in the Hassai
Supergene composite were pyrite (55%) and chalcopyrite (23%), accounting for 78%
of the mineral mass. As for Hassai Primary composite, pyrite and chalcopyrite
were the predominant sulfide minerals accounting for 80% and 6% of the mineral
mass respectively. The most abundant non-sulfide gangue mineral type was
silicates, which accounted for 7% of the mineral mass.
Flotation Test Work
A total of thirteen rougher kinetics and batch cleaner flotation tests were
performed on the Hassai Supergene zone composite and Primary zone composite. In
addition, a locked-cycle test was performed on each of the two composites. The
test work explored the effect of primary grinding, pulp pH, collector dosage and
re-circulating loads. The locked-cycle tests are designed to emulate the
metallurgical response in the concentrator plant. The test results are used as a
basis for preliminary plant design. As reported in table 1, the final copper
recovery for Hassai Primary composite in the locked cycle test was 84.9%
following an average open circuit rougher copper recovery of 87%. However, in
identical roughing stages in batch tests (with the same sample) the rougher
copper recoveries ranged from 93% to 95%. On this basis it has been assumed that
the locked cycle recoveries are underestimated due to poor roughing stage
performance.
A final concentrate from locked-cycle tests (Cycle F) for each of the Hassai
Supergene composite and Primary composite was submitted for detailed concentrate
analysis. For the Hassai Supergene composite, the final concentrate copper grade
was 30.2% with 25.1 g/t gold. As for the Hassai Primary composite, copper was
graded 25.1% with 11.6 g/t gold. No deleterious elements were present in either
final concentrate, indicating that the concentrate should be readily saleable.
Gold Extraction from Concentrator Tailings
Gold extraction from a series of flotation test products was evaluated at a
scoping level. Pyrite scavenger concentrate and 1st cleaner scavenger tailing
representing both the Supergene and Primary zone materials were tested. These
products were generated in locked-cycle tests. The initial pair of tests, one on
each composite, was conducted on pyrite scavenger concentrate generated in
smaller-scale batch tests. The primary purpose of these tests was to
approximately determine the potential for gold recovery. Parameters evaluated in
these tests included leach retention time, feed particle size and cyanide
concentration.
Gold leach processing of the concentrator tailings is still being modeled by
AMEC Minproc, and the results are not yet available.
QUALIFIED PERSONS
Metallurgical test work was conducted by SGS Canada Inc. in Lakefield, Ontario,
Canada, and was under the direct supervision of James MacDonald, Senior
Metallurgist. James has 25 years experience in the mineral processing field and
is currently a senior metallurgist/project manager within the SGS Canada,
Metallurgical Operations, Gold Group.
The PEA is being prepared by AMEC Minproc in Perth, Western Australia, under the
supervision of Dean David, Process Consultant. Dean has 27 years experience in
mineral processing research, operations, management and consulting. His
expertise covers most aspects of mineral processing technology. He has a
Bachelor of Applied Science (Metallurgy) from the South Australian Institute of
Technology SA, Australia. Dean was Manager Process at AMEC Minproc for two years
and since mid 2005 has been Process Consultant. He participated in the majority
of mineral processing studies and projects conducted by Minproc in the past six
years, typically in a reviewing and consulting role.
Bill Plyley, COO of La Mancha acts as project coordinator of the project. Mr.
Plyley is a seasoned mining veteran, with more than 35 years management and
hands-on experience in international mining industries. Mr. Plyley holds a BSc.
in Metallurgical Engineering from the Mackay School of Mines, University of
Nevada, Reno.
Dean David and Bill Plyley are Qualified Persons as defined by National
Instrument 43-101. They have read National Instrument 43-101 of the Canadian
Securities Administrators ("NI 43-101") and have ensured that this press release
is in compliance with it.
The 43-101 resource figures quoted in the text of this press release were
disclosed in press releases issued on September 10, 2009, and November 4, 2009,
and are detailed in two technical reports dated October 26 and December 21,
2009.
ABOUT LA MANCHA RESOURCES INC AND THE VMS PROJECT:
La Mancha Resources Inc. is an international gold producer based in Canada with
operations, development projects and exploration activities in Africa, Australia
and Argentina. La Mancha's shares trade on the Toronto (TSX) under the symbol
"LMA". For more information on the Company, visit its website at
http://www.lamancha.ca/.
The Hassai mine is located in the Red Sea Hills desert of northeastern Sudan,
some 450 km from Khartoum. Inaugurated in 1992, it is Sudan's first and only
gold mine in production. Twelve pits have been mined over the years, generating
a cumulative production of more than 2.1 million ounces of gold. La Mancha owns
40% of the mine through a subsidiary and is the mine operator. The Hassai
exploration licenses effectively encompass the entire geological district that
extends over 24,000 square kilometres. In late 2009, La Mancha reported the
first 43-101 Inferred VMS resource for the Hassai property.
CAUTION CONCERNING FORWARD-LOOKING STATEMENTS
This press release contains certain "forward-looking statements", including, but
not limited to the statements regarding the Company's strategic plans, future
commercial production and profitability, development and construction of mine
and production targets and timetables; statements regarding the Company's
ability to reproduce the recoveries obtained by SGS in their lab testing on an
industrial basis; statements regarding the possibility to economically
re-process the concentrator's tailings to improve gold recoveries; statements
regarding the Company's ability to deliver a Preliminary Economic Assessment on
the VMS project during the third quarter of 2010; Forward-looking statements
express, as at the date of this press release, the Company's plans, estimates,
forecasts, projections, expectations or beliefs as to future events and results.
Forward-looking statements involve a number of risks and uncertainties, and
there can be no assurance that such statements will prove to be accurate.
Therefore, actual results and future events could differ materially from those
anticipated in such statements. Risks and uncertainties that could cause results
or future events to differ materially from current expectations expressed or
implied by the forward-looking statements include, but are not limited to,
factors associated with fluctuations in the market price of precious metals,
mining industry risks, exploration risks, risks associated with foreign
operations, environmental risks and hazards, uncertainty as to calculation of
mineral reserves, requirement of additional financing or additional permits,
authorizations or licenses, risks of delays in construction and production and
other risks referred to in La Mancha's 2009 Annual Information Form filed with
the Securities Commissions, as well as the Toronto Stock Exchange.
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