Trading Symbol: PAX.TSX-V
VANCOUVER, Feb. 13 /CNW/ - Pacifica Resources Ltd. (PAX.TSX-V) reports on
positive results from gravity separation testwork on samples from Anniv,
Brodel and XY deposits at their Howard's Pass project. The recent
metallurgical program was designed to evaluate the specific gravity
characteristics of the zinc-lead mineralization at the Howard's Pass property.
Samples were collected from Anniv, Brodel and XY zones and are considered to
be representative of the Run-of-Mine (ROM) ore feed. The separation of dense
(zinc and lead) mineralization from less dense (gangue) waste provides an
effective pre-concentration before milling.
In April, 1977 US Steel Corporation conducted a similar study of gravity
testwork on mineralization from Howard's Pass which gave positive results.
Their testing showed a mineral (zinc-lead) content upgrade of over 200% with a
rejection of 70% of the run-of-mine (ROM) material. The combined lead/zinc
grades went from 10.9% to 29.2% with a lead and zinc recovery of 87% and 76%
respectively.
Highlights:
- Gravity separation testwork by Pacifica demonstrated rejection of
39.4% to 45.87% of the ROM material, which provided an upgrade of mill
feed material to 140% to 150% for zinc and 150% to 160% for lead.
- Testwork confirms high recoveries previously obtained in US Steel's
1977 testwork and in preliminary testwork undertaken by Pacifica in
2004. (see July 21, 2005 news release).
Mineralization at Howard's Pass consists of banded zinc-lead
mineralization intercalated with barren to weakly mineralized shale beds.
Specific gravity of the banded zinc-lead mineralization varies from 4.0 to 7.6
compared to the less dense gangue zones that range from 2.0 to 2.8. The ROM
has an overall specific gravity range of 2.8 to 3.0 reflecting a high
proportion of waste in the ROM.
The laboratory testwork was completed at SGS Lakefield Research under the
supervision of Pacifica's metallurgical consultant Godfrey McDonald. Further
metallurgical testwork (flotation) on products from the gravity study is
currently in progress. Mr. McDonald is the Qualified Person within the meaning
of NI 43-101.
The laboratory evaluation was done on samples (15 kilograms each) using
Heavy Liquid Separation (HLS) for the separation at designated specific
gravities of 2.6, 2.8 and 3.0. These laboratory results can be extrapolated
for design and operation of a production sized DMS plant. DMS uses cyclones
and heavy media to effect the gravity separation of materials based on the
contrast of specific gravity of materials.
Samples for HLS testing consisted of diamond-drill core from the Anniv (2
holes) and Brodel (1 hole) deposits and a fourth sample obtained from the
surface muck piles which were part of the underground mining done on the XY
deposit in late 1970's. Samples were collected to represent ROM ore ranging
from 5 to 10% combined zinc and lead.
Each sample was crushed to minus 1/2 inch. The crushed samples were "wet"
screened on a 14 mesh screen cloth to remove fines that could affect the HLS
and/or DMS processes. These fines contain mineral values so they by-pass the
specific gravity separation and are included in the final mill feed. The plus
14 mesh screen product is placed in a bath of heavy liquid at specific gravity
3.0. The "Float" portion is scooped out of the bath for subsequent processing.
The "Sink" portion is removed from the bath, washed to remove the heavy liquid
from it's surfaces, dried, weighed and prepared for assaying.
The "Float" (specific gravity 3.0) is placed in the second bath with
specific gravity 2.8 and the process repeated. The process is again repeated
with "Float" portion at density 2.8 processed in a bath with specific gravity
of 2.6. The original screen fines are part of the final mill feed. The "Float"
product at specific gravity 3.0, 2.8 and 2.6 are considered to be process
"reject" at the respective, specific gravity of the mass balance calculation.
The following tables show the average material balance at an extrapolated
specific gravity of 2.7 for the following drill hole samples and from
underground samples from the XY deposits. The previously reported results are
included in the lower part of the table.
<<
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Anniv - DD Hole 75 Assays Recoveries
-------------------------------------
Weight % %Pb %Zn %Pb %Zn
-------------------------------------------------------------------------
Float 45.87 0.34 1.56 12.91 18.29
Mill Feed 54.13 1.93 5.90 87.09 81.71
ROM 100 1.20 3.91 100 100
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Anniv - DD Hole 76 Assays Recoveries
-------------------------------------
Weight % %Pb %Zn %Pb %Zn
-------------------------------------------------------------------------
Float 43.10 0.61 2.51 15.49 21.17
Mill Feed 56.90 2.55 7.11 84.51 78.83
ROM 100 1.71 5.13 100 100
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Brodel - DD Hole 2 Assays Recoveries
-------------------------------------
Weight % %Pb %Zn %Pb %Zn
-------------------------------------------------------------------------
Float Mill 45.39 0.26 1.11 11.91 16.70
Feed 54.61 1.63 4.58 88.09 83.30
ROM 100 1.01 3.01 100 100
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XY Grab Samples 2005 Assays Recoveries
-------------------------------------
Weight % %Pb %Zn %Pb %Zn
-------------------------------------------------------------------------
Float Mill 39.4 0.39 1.87 5.40 10.3
Feed 60.6 4.47 10.58 94.60 89.7
ROM 100 2.86 7.15 100 100
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XY Grab Samples 2004(x) Assays Recoveries
-------------------------------------
Weight % %Zn+Pb %Pb %Zn
-------------------------------------------------------------------------
Mill Feed 72.0 29.0 98 97
ROM 100 21.8 100 100
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US Steel 1977(x) Assays Recoveries
-------------------------------------
Weight % %Zn+Pb %Pb %Zn
-------------------------------------------------------------------------
Mill Feed 28.0 29.2 87 76
ROM 100 10.9 100 100
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(x) Results reported in July 21, 2005 news release
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The diamond drill core increment samples (Anniv and Brodel) were sawed
"quarter" core increments that were crushed to minus 1/2 inch. Crushing of
this material resulted in non-representative breakage of mineralization and
gangue material which likely contributed to loss of some zinc and lead with
"Float" reject particles.
The grab samples from the XY underground development muck piles were made-
up of bigger lump sized ROM ore. The crushing to minus 1/2 inch for this
material results in more natural breakage that is more indicative of expected
breakage to the natural "grain, boundaries" such that the "Float" reject is
higher in weight percent and metal mineral losses are lower. It is suggested
that the results for the samples from muck piles of XY mineralization better
represents the likely outcome of what could be expected from DMS testwork.
The positive, preliminary testwork results illustrate the potential for
pre-concentration of mineralization from a wide range of run-of-mine (ROM)
grades in the Howard's Pass deposits. The potential successful application of
DMS technology reflects the unique character of the mineralization and the
strong contrast in specific gravity of mineralization and waste. The
pre-concentration of the ROM material has significant benefits to milling
process, with potential higher metal throughput, and significantly lower
operating and capital cost. Test work will continue to evaluate and refine
application of gravity technology on the Selwyn Project.
Pacifica's main focus is the exploration of its properties in the
Howard's Pass District, Yukon that hosts large tonnages of zinc-lead
mineralization. The known deposits have the potential for large scale
production of zinc and lead, at a time when world zinc mine supply is in
deficit and there are few new mines under development. As follow-up to the
successful 2005 exploration program, Pacifica is planning an $8 million
exploration program in 2006 to continue definition drilling of the XY, Anniv,
and Brodel deposits. Drilling is also planned to test the large areas of the
basin that have not previously been drilled to determine the extent and grade
of mineralization in this large mineralized system that currently has a strike
length of at least 30 kilometres.
This press release may contain forward-looking statements based on
assumptions and judgments of management regarding future events or results
that may prove to be inaccurate as a result of exploration and other risk
factors beyond its control and actual results may differ materially from the
expected results.
THE TSX VENTURE EXCHANGE HAS NOT REVIEWED AND DOES NOT ACCEPT
RESPONSIBILITY FOR THE ADEQUACY OF THIS NEWS RELEASE.
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