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Canadian Zinc Reports Positive Metallurgical Test Results for
Prairie Creek Mine
On Thursday June 4, 2009, 3:17 pm EDT
Buzz up! Print.VANCOUVER, BRITISH COLUMBIA--(MARKET WIRE)--Jun 4,
2009 -- Canadian Zinc Corporation (Toronto:CZN.TO - News)(OTC
BB:CZICF.OB - News) reports recent positive results from ongoing
(Phase 5) metallurgical testing relating to its planned Prairie
Creek zinc/lead/silver mine in the Northwest Territories of
Canada.
In late 2008 a 530 kg representative rock sample of mineralized
vein material was extracted from multiple headings within the
underground workings at the Prairie Creek Mine. The sample was
composited at SGS Lakefield Research for large scale locked cycle
testing with the objective of producing representative
concentrates, tailings and process effluents using the actual
proposed process flow sheet for the Prairie Creek Mine. This flow
sheet has been presented in the Project Description Report, dated
May 2008, submitted as part of the applications for operating
permits, which are presently the subject of Environmental
Assessment being carried out by the Mackenzie Valley Environmental
Impact Review Board ("MVEIRB").
In addition, a large volume of representative mine water was also
collected at that time and shipped to SGS Lakefield for use in the
same locked cycle tests to better simulate actual site operating
conditions.
Metallurgical Test Results:
Heavy Liquid Separation:
Previous metallurgical studies incorporated a Heavy Liquid
Separation ("HLS") process applied to the Run of Mine (ROM) feed to
optimize the existing mill at the Prairie Creek Mine by enhancing
the metal grade entering into the flotation process, and thus
reducing the amount of waste being needlessly processed. HLS is
used in the laboratory to simulate the process of Dense Media
Separation ("DMS") which will be undertaken on a commercial
scale.
A composite ROM sample was stage crushed to a nominal 1/2 inch
size. The composite was then screened at 14 mesh with the minus 1/2
inch and plus 14 mesh processed through a HLS plant. This resulted
in 41% of the ROM composite being rejected as waste with a loss of
only 2.5% total lead and 4.4% total zinc metal values. Waste
rejection from the previous DMS studies averaged -30%. The higher
number in this recent case is a significant improvement but may
relate to the inherent variability of dilution in the mining of
mineralized vein structures to collect the bulk sample. The HLS
test result is consistent with the previous studies in that it
demonstrated that a significant increase in mill throughput and
grade can be achieved with a minimal loss of economic metals of
less than 5%.
The results of the HLS (DMS) test work are presented in the
following table:
----------------------------------------------------------------------------
Product Weight Assays % % Distribution
% Pb Zn Pb Zn g/t Pb Zn Pb Zn
(T) (T) (ox) (ox) Ag (T) (T) (ox) (ox) Ag
----------------------------------------------------------------------------
Minus 1/2"
+14m HLS
Sink 31.9 28.3 26.9 6.44 4.48 453 73.27 57.13 49.95 42.04 59.52
Minus 14m 27.1 11.0 21.3 6.81 5.64 339 24.23 38.49 44.95 45.03
37.90
Minus 1/2"
+14m HLS
Float 41.0 0.75 1.6 0.51 1.07 15.2 2.50 4.38 5.10 12.93 2.57
----------------------------------------------------------------------------
ROM comp
head
(calc) 100 12.31 15.00 4.11 3.40 242 100 100 100 100 100
----------------------------------------------------------------------------
Mill Feed
after HLS 59.0 20.35 24.33 6.61 5.01 401 97.5 95.6 94.9 87.1
97.4
----------------------------------------------------------------------------
T equals total sulphide and oxideThe HLS enhanced plant mill feed
was then combined, mixed, and crushed to 10 mesh in preparation for
the locked cycle flotation test work.
Locked Cycle Flotation Tests:
After crushing and grinding the HLS enhanced mill feed was
delivered into a locked cycle flotation test where concentrates of
lead sulphide, zinc sulphide and lead oxide were generated. No
separate zinc oxide flotation was completed since previous
metallurgical studies indicated low concentrate grades and low
recoveries for zinc oxide.
The locked cycle tests were designed to produce concentrates,
tailings and effluent for engineering, marketing and environmental
studies and in using active means. The reagent scheme used in the
locked cycle tests was developed from previous studies and slightly
modified for use with the actual mine water. Small scale batch
tests were run prior to the locked cycle tests with the objective
of optimizing selectivity between lead and zinc.
Three large-scale locked cycle tests were performed.
The test results indicate that the overall grade of the blended
lead sulphide / oxide concentrate assayed 67% lead, with a 82%
recovery of total lead in the plant feed, and the zinc sulphide
graded 58% Zn with a 74% recovery of the total zinc in the plant
feed. An average of 92.7% of the total silver values in the plant
feed was recovered within the lead and zinc concentrates.
"The recent metallurgical tests generated very satisfactory
simulated results of anticipated actual operations in the
production mineral concentrates at the Prairie Creek Mine," said
Alan Taylor, Chief Operating Officer of Canadian Zinc.
"The Phase 5 test results showed concentrate grades and recoveries
similar to results of previous locked cycle tests, allowing for
variations within the individual bulk samples, and confirmed
anticipated concentrate grades and recoveries under simulated
actual proposed milling operations and using representative actual
mine water." Mr. Taylor added.
The generated by-products of HLS reject and flotation tailings from
the Phase 5 metallurgical tests are currently undergoing further
study and characterization by Golder Paste Technology Ltd., of
Sudbury, Ontario to assist in developing a new plan for the
permanent disposal of paste tailings underground. Similarly CEMI
Labs of Burnaby are further testing various water treatment options
on the process effluent generated from this phase of metallurgical
testing to ensure a sound treatment scheme during the operation of
the Prairie Creek mine. Further study directed towards reducing the
amount of certain deleterious elements within the concentrates,
(eg. mercury, antimony and arsenic) to enhance payability, is also
being examined.
The results of the test work will be used in pursuing marketing and
treatment alternatives for the Prairie Creek concentrates and will
also be incorporated into the Developers Assessment Report to be
submitted to the Mackenzie Valley Environmental Impact Review Board
later this year once Final Terms of Reference for the environmental
assessment are issued. The MVEIRB issued Draft Terms of Reference
for comments to be submitted by June 12, 2009 and finalization
shortly thereafter.
Proposed Operations at Prairie Creek Mine:
The proposed new operation at Prairie Creek utilizes the existing
infrastructure and facilities that were built in the 1980s and
which will be upgraded and enhanced to meet current-day
environmental standards.
The Mill, which is already constructed on site but never operated,
will process 600-1,000 tonnes per day. Ore will be crushed to a
gravel-size and passed through a new DMS plant. The lighter,
uneconomic "gangue" minerals will create a waste rock aggregate.
The more dense material will be processed further by grinding and
flotation to produce concentrates of lead sulphide, zinc sulphide
and lead oxide. No hazardous chemicals will be used in the
process.
The existing large pond facility, originally intended in 1980 for
tailings disposal, will be reconfigured, relined and recertified to
form a two-celled Water Storage Pond.
Underground Tailings Disposal:
In recognition of concerns about tailings disposal, and following
extensive research, Canadian Zinc has developed a new tailings
management plan. The Company proposes to place all mill tailings
permanently underground as paste backfill, together with
approximately three quarters of the DMS waste rock and a cement
binder. The mix will solidify after placement into a form of
concrete. In this manner all mill flotation tailings will be
backfilled into the voids in the underground mine with the waste
rock aggregate. The flotation tailings are expected to be non-acid
generating with low sulphide content and excess buffering
capacity.
The benefits of this new tailings management plan are that all
tailings will be placed underground and there will be no permanent
disposal of tailings on surface.
Qualified Person:
Alan Taylor, P.Geo., Chief Operating Officer & Vice President
Exploration and a Director of Canadian Zinc Corporation, is the
Company's non-independent Qualified Person for the purposes of NI
43-101 and has approved this press release.
The Prairie Creek Mine:
A major underground tunneling and diamond drilling program led to
the completion, in October 2007, of a Technical Report (the
"Report") to National Instrument ("NI") 43-101 standards, which
estimates that the Prairie Creek Property hosts total Measured and
Indicated Resources of 5,840,329 tonnes grading 10.71% zinc, 9.90%
lead, 161.12 grams silver per tonne and 0.326% copper. In addition,
the Report confirms a large Inferred Resource of 5,541,576 tonnes
grading 13.53% zinc, 11.43% lead, 215 grams per tonne silver and
0.514% copper and additional exploration potential.
The Measured
and Indicated Resource is capable of supporting a mine life in
excess of ten years at the planned 1,000 tonnes per day mining
rate.
gute Kurse
supertai