Xtierra Inc.: Final Steps for Bilbao Feasibility Study
08 6월 2012 - 5:41AM
Marketwired Canada
Xtierra Inc. (TSX VENTURE:XAG) ("Xtierra" or the "Company"), is pleased to
report that at the Annual Meeting held in Toronto on June 6, 2012, shareholders
were provided with an update on the progress of the Feasibility Study at the
Company's Bilbao project, which is anticipated to be completed in the third
quarter of 2012.
Bilbao Feasibility Study
In 2010, Xtierra retained DRA Americas, a consulting engineering firm with
expertise in process engineering, to oversee and complete the Bilbao Feasibility
Study. DRA is involved in oversight of all of the component parts of the
Feasibility Study as well as managing all the metallurgical test work. The
Feasibility Study is comprised of metallurgical test work on the oxide, mixed
and sulphide mineralization, geotechnical studies, hydrogeological studies,
topographic surveys, mine planning and engineering studies, capital and
operating costs and environmental and permitting studies.
During Q1 2012, work was conducted in developing a detailed mine plan for the
underground areas, including evaluation of underground mining methods and design
of an access ramp and necessary stope development. Xtierra has retained Golder
Associates to advise on tailings disposal and related plant design work. In
order to optimize water consumption, reduce and simplify the design of the
tailings disposal impoundment infrastructure and generate material for back
filling the underground stopes, production of paste tailings is being
considered.
Geotechnical, hydrogeology and electrical power distribution infrastructure
studies have been completed and are under review by DRA.
Based on the metallurgical results received to date it is expected that the
Feasibility Study will recommend the initial development of an underground mine
and the processing of the sulphide and transition resources. The development of
the open pit mine and processing of the oxide ore would be deferred and would
occur later in the mine life, subject to further metallurgical optimization of
the oxide process flow sheet and open pit resource optimization.
Items to be completed in the Feasibility Study include final optimization of the
sulphide and transition ore process flow sheet to possibly include the
production of a copper concentrate in addition to lead and zinc concentrates,
completion of underground mine plans and schedules, completion of tailing
disposal plans, completion of a final EIA, securing surface and water rights,
and finalization of operating and capital cost estimates.
Metallurgical Testing and Studies
Because the mineralization at Bilbao comprises both oxide and sulphide material,
together with some mixed transitional mineralization, much of the Company's
efforts has focused on developing metallurgical approaches to economically
recover the various mineralized types and this has involved multiple stages of
metallurgical testing and design.
The first reported metallurgical studies were carried out during 1994-1995, by
Lakefield Research as part of a consulting consortium consisting of Watts
Griffis & McOuat and Kilborn Engineering. The results of those studies presented
a case for open-pit mining with differing scenarios for metallurgical processing
and metal recovery. At that time Lakefield investigated gravity, flotation and
leaching with thio-urea and cyanide without satisfactory recovery of lead or
silver. Copper and zinc would be recovered by leaching with sulphuric acid and
use of solvent extraction with electrolytic precipitation of the copper and
zinc.
Additional metallurgical test work was carried out by Xtierra in 2008/2009 at
the Metallurgical Institute of the University of San Luis Potosi using a process
of wet high intensity magnetic separation (WHIMS) and acid leaching on oxide
mineralization.
Based on the WHIMS results a decision was made to proceed with a pilot plant
test program to confirm the process flow sheet and enable the design of a
processing plant to treat the oxide mineralization. Four composite samples were
extracted from two underground levels (historic workings) and from near surface,
representing the majority of the oxide resource. A pilot plant sized crusher,
ball mill and WHIMS were set up at the Bilbao project site to prepare and
produce a pre-concentrate, which was shipped for processing to the SGS
laboratories in Durango, Mexico and Lakefield, Ontario. The initial test results
indicated only moderate recoveries, particularly for lead, from the oxide ore.
Since 2010, DRA has been overseeing the ongoing metallurgical test work. DRA
recommended that further open circuit bench scale laboratory test work be
concluded on both pre-concentrated and whole ore (no pre-concentration) prior to
conducting a closed circuit or locked cycle test programme. This test work was
initially performed at the SGS Laboratory in Durango, Mexico and subsequently at
the SGS Laboratory in Lakefield, Ontario.
After numerous tests conducted on optimizing the pre-concentration process for
oxide ores by means of wet high intensity magnetic separation it was concluded
that there was no appreciable benefit in reducing overall acid consumption
relative to processing whole ore. It was also concluded that there is no
meaningful benefit in including the WHIMS pre-concentration process in the
flow-sheet for the treatment of the oxide ore.
The results of the test-work on the oxide ore completed to date indicates that
while it is possible to achieve acceptable recovery levels the costs involved in
doing so, particularly for the amounts of reagent consumption required, would be
expensive. Further metallurgical test work on the oxides to optimize economic
metal recoveries, including the recovery of lead by means of gravity separation,
has shown some promise and additional metallurgical test-work will be continued
at a later date.
In 2011, DRA recommended a final phase of metallurgical test work on the
sulphide and mixed transition ores, including locked cycle test work. Two drill
holes were completed in the Q3 2011 for metallurgical sample purposes,
generating material for flotation test work as well as grinding determinations.
The flotation test work, conducted at SGS laboratories in Lakefield, Ontario,
began in November 2011 and completed in Q2 2012, was carried out on both
sulphide and transition ores and included locked cycle testing with good results
indicated. Testing of the effects of co-mingling the mixed transition ores with
the sulphide ore was also conducted.
It is anticipated that the remaining planned metallurgical test work will be
completed and the final metallurgical reports will be received by the end of Q2
2012 and incorporated into the Feasibility Study.
Bilbao Mineral Resources
The Bilbao deposit is a replacement-style deposit with a skarn overprint and is
located adjacent to the La Blanca granodiorite. The Bilbao mineralization forms
zones dipping at shallow angles ranging up to about 45 degrees. The
mineralization has been oxidized to a depth of about 70m below the surface,
below which there is an irregular zone of mixed oxide-sulphide mineralization
varying between 20 - 100m in thickness. The sulphides continue to a depth of
about 230m.
Between 2006 and 2009 the Company carried out a series of exploration drilling
programs as a result of which the size of the deposit was increased from the
original historical estimate of about 3.45 million tonnes to about 6.0 million
tonnes. Subsequent drilling in 2010 and 2011 further expanded the resources to
the current level of 10.6 million tonnes and the deposit remains open,
particularly to the south where recent exploration drilling has identified two
silver targets immediately to the south of the Bilbao deposit. Further infill
drilling is currently being carried out on the deposit.
An independent resource estimate was prepared in April 2011 by R.T.G. Parker,
C.Eng., an independent consulting mining geologist and a 'Qualified Person'
within the meaning of NI 43-101 - Standards of Disclosure for Mineral Projects
of the Canadian Securities Administrators. The resource estimate was calculated
using a 3% zinc equivalent cut off and includes sulphide, oxide and mixed ore
categories and is summarized in the table below.
Resource Category Tonnes Lead Copper Zinc Silver
(millions) (%) (%) (%) (gpt)
----------------------------------------------------------------------------
Indicated Resources 10.62 2.00 0.19 2.13 53.81
Inferred Resources 0.43 1.73 0.18 1.44 46.39
Technical Report dated April, 2011 entitled "Geology and revised Minerals
resources of the Bilbao Silver-Lead-Zinc Deposit - State of Zacatecas, Mexico"
by RTG Parker, Consulting Geologist.
The resource, comprising the current Bilbao deposit, is made up of primary
sulphide mineralization below approximately 70 metres depth (50% of the
resource) and oxide mineralization which extends from surface to a depth of
about 70 metres (35% of the resource). There is a narrow but irregular zone of
transition mixed mineralization between these two categories comprising 15% of
the resource.
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BILBAO INDICATED RESOURCES AT 3% ZNEQ CUTOFF (APRIL 2011 RTG PARKER -
INDEPENDENT QUALIFIED PERSON)
----------------------------------------------------------------------------
ORE TONNES
TYPE (000's) GRADE TONNES METAL
----------------------------------------------------------------------------
Cu Pb Zn Ag Zneq Cu Pb Zn Ag Zneq
% % % g/t %
----------------------------------------------------------------------------
OXIDE 3,735 0.20 2.16 1.94 48.41 6.35 7,470 80,671 72,454 181 237,158
----------------------------------------------------------------------------
MIXED 1,584 0.16 2.06 2.35 53.43 6.66 2,535 32,634 37,228 85 105,534
----------------------------------------------------------------------------
SULPHIDE 5,299 0.19 1.86 2.19 57.72 6.52 10,068 98,561 116,047 306 345,566
----------------------------------------------------------------------------
TOTAL 10,618 0.19 2.00 2.13 53.81 6.48 20,072 211,865 225,730 571 688,258
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Qualified Person
Information of a scientific or technical nature contained in this release has
been prepared by or under the supervision of Terence N. McKillen, P.Geo., Chief
Executive Officer, Gerald J. Gauthier, P.Eng., Chief Operating Officer and Dr.
Anthony C. Gallon, C.Eng., Chief Geologist, all 'Qualified Persons' within the
meaning of National Instrument 43-101 - Standards of Disclosure for Mineral
Projects of the Canadian Securities Administrators.
About Xtierra Inc.
Xtierra Inc. is a Toronto based exploration and development company listed on
the TSX Venture Exchange under the symbol "XAG". There are 103,272,142 shares
issued and outstanding. The Company is completing a feasibility study on its
Bilbao silver-zinc-lead-copper project in Zacatecas, Mexico. Xtierra's objective
is to become a mid-tier producer of precious and base metals through the
development of its Bilbao project as well as through exploration, organic growth
and M & A opportunities.
For further information visit www.xtierra.ca.
Xtierra (TSXV:XAG)
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