Metallurgical Tests Indicates 87% Gold Recovery in Gravity
Testwork from the Waste Stockpile, and 96% Recovery of Gold in
Cyanide Leach Testwork from the Low Grade Tailings.
TORONTO,
April 23, 2013 /CNW/ - Laurion
Mineral Exploration Inc. (TSX.V: LME; OTCQX: LMEFF)
("Laurion") is pleased to announce that NI 43-101 Measured
and Indicated resource estimates have been prepared by Laurion's
consultants GeoVector Management Inc. ("GeoVector") for
Laurion's Ishkoday Property, located approximately 28km northeast
of Beardmore, Ontario. The
resource estimates are for the low grade stockpile accumulated
during mining operations of the old Sturgeon River Gold mine on the
Ishkoday property from 1936 to 1942, and for the low grade tailings
area associated with the processing of ore feed from the mine.
The resource estimate for the low grade
stockpile is 144,070 tonnes grading 1.59 g/t gold for 7,383
contained ounces of gold in the Indicated category. The resource
estimate for the low grade tails is 137,501 tonnes grading 0.67 g/t
gold for 2,944 contained ounces of gold in the Indicated
category. Total Indicated mineral resources for both deposits
totals 281,571 tonnes grading 1.14 g/t gold for 10,327
contained ounces of gold.
Cynthia Le
Sueur-Aquin, Laurion's President and CEO commented,
"Initially, the broad objective of evaluating the low grade
stockpile and the tailings area was to prove the encouraging extent
and grade of the host rock mineralization between high grade quartz
veins.
Ore mined between the years 1936-42, was hand
sorted at surface, extracting the higher grade quartz vein
material. The lower grade vein selvages were placed on the low
grade stockpile. The sampling and resource estimation indicates
that this material contains significant gold. We fully anticipate
that the base of the low grade stockpile and tailings area may well
contain higher gold grade values, as a result of percolation of
gold fines over the 70 years of weathering. The highest grade
sample in the low grade stockpile was 32 g/t Au. That gold
mineralization occurs outside the traditionally mined veins was
further confirmed in 2010, with the discovery of 7 new gold zones
reported in the assay results of the 3,511 m drill program below
the shaft workings. This mineralizing style appears to be
indicative of a larger lower grade gold environment and potential
to explore a mining opportunity in an around the historical shaft
area.
The Ishkoday property continues to surprise
and deliver encouraging results. The resource estimates of 7,383
ounces gold contained in the low grade stockpile and 2,944 ounces
gold in the low grade tailings is a bonus to the comprehensive
sampling program, and is currently being evaluated for potential
economic recovery and revenue generation".
LOW GRADE STOCKPILE
MINERAL RESOURCE ESTIMATE of the LOW GRADE
STOCKPILE
The resource estimate for the low grade stockpile is 144,070 tonnes
grading 1.59 g/t gold for 7,383 contained ounces of gold in
the Indicated category for all material in the stockpile. A
10g/t cut on all top assay values was applied. As the resource is
for a broken stockpile no cut-off grade was applied to the reported
resource, as any practical recovery will require processing of all
material in the pile. Results at various gold cut-off grades for
the low grade stockpile are tabulated below:
MINERAL RESOURCE TABLE of the LOW GRADE
STOCKPILE
Cut-off
Au g/t |
Tonnes |
Au (g/t) |
Grade (g/t) |
Grams (Contained) |
Ozs (Contained) |
<0.1 |
144,070 |
1.59 |
229,619 |
7,383 |
0.1 |
140,688 |
1.63 |
229,619 |
7,383 |
0.2 |
139,821 |
1.64 |
229,456 |
7,378 |
0.3 |
138,555 |
1.65 |
229,111 |
7,367 |
0.4 |
133,684 |
1.70 |
227,435 |
7,313 |
0.5 |
128,603 |
1.75 |
225,141 |
7,239 |
1.0 |
96,518 |
2.08 |
200,794 |
6,456 |
The resource estimate was based on a
comprehensive program commissioned by Laurion in 2010 to accurately
determine the location and volume of the low grade stockpile, and
to sample the stockpile using an excavator. The excavator dug pits
to acquire representative samples throughout the pile. This
information was used to calculate a 43-101 compliant resource
estimate.
The survey of the waste pile was carried out by
TBT Engineering Consulting Group ("TBTE") of Thunder Bay, using a Trimble R8 RTK GPS with
an accuracy of approximately 1 cm. The excavations were also
carried out by TBTE with hole locations determined using the
Trimble GPS. Depth of the excavated pits was determined using a
tape measure to 10 cm scale accuracy. A total of 30 pits were
excavated and 46 samples were collected, with deeper pits (maximum
5.2 metres deep) providing 2 or 3 samples at successively deeper
levels.
Sampling of the excavated material was carried
out by GeoVector to acquire samples that were representative of
rock type and broken rock size. Samples were collected in 20 litre
pails and delivered to Overburden Drilling Management ("ODM") in
Ottawa, Ontario. Individual sample
weights were between 20.8-30.7 kg and total sample weight tested
was 1.22 tonne. ODM sorted the individual samples into 4 fractions
of >63mm, 63-16mm, 16-2mm and <2mm. This separation tested an
assumption that the finer fraction material contains more gold as
the mine operators during its 1936-1942 production period had
sorted coarse quartz vein material for milling, and the finer high
grade material would have gone to the waste pile.
The size fractions from the samples were sent by
ODM to Actlabs and they were analyzed by fire assay with AA finish.
Any high grade samples over 3000 ppb gold were further treated to
fire assay with gravimetric finish to determine a final gold
grade. Summary results of the assaying included:
Size Fraction |
Minimum Grade (Au
g/t) |
Maximum Grade (Au
g/t) |
Average Grade (Au
g/t) |
>63 mm |
Nil |
32.00 |
0.97 |
63mm-16 mm |
0.02 |
7.16 |
0.77 |
16mm-2mm |
0.05 |
4.84 |
0.98 |
< 2mm |
1.77 |
14.3 |
6.20 |
As indicated by the above table the smallest
size fraction (< 2mm) had the highest grade material (6.20 g/t
Au average), and all samples in this size fraction had assays
greater than 1.75 g/t. The coarsest fraction (> 63 mm) had
erratic high values reflecting occasional quartz cobbles, and also
contained the highest grade sample (32 g/t Au). These assay results
and the survey data were incorporated into an ore resource estimate
by GeoVector.
The mineral resource model was constructed in
Gemcom GEMS 6.4. The model is based on the survey data. A block
model with the origin at 444120E, 5511110N, 347m elevation was
constructed using 4 x 4 x 0.5 metre blocks in the x, y, and z
direction respectively. Grades for gold were interpolated into the
blocks by the inverse distance squared method using between two and
six composites to generate block grades. The size of the search
ellipse was set at 50 x 50 x 10 metres in the X, Y, Z direction
respectively for the indicated resource. The Principal and
Intermediate azimuths create a circular ellipse and the Principal
dip is oriented at 0°. An average SG value of 2.00, appropriate for
broken run of mine material, was applied to all blocks within the
block model.
METALLURGICAL TEST RESULTS of LOW GRADE
STOCKPILE SAMPLES
Following the assaying of the sample fractions from the low grade
stockpile a composite sample was carefully selected from the
remaining reject. The composite sample totalled 78.3 kilograms and
was designed to be representative of the average grade of material
within the stockpile block model. Assayed head grade for the sample
was 1.75 g/t gold.
The tests included gravity concentration using a
Knelson Concentrator and cyanidation. The results of the gravity
recovery test indicate that at a fine grind of 97% passing -75μm
87.58% of the gold in the sample is able to be recovered by gravity
concentration, which indicates an ore exceptionally amenable to
Gravity Concentration methods. The cyanidation tests indicated that
a grind of 97% -75 μm provided extractions of 92-93%. The
combination of Knelson Concentration with cyanidation of the
gravity tailings gave a combined recovery & extraction of
98.5%.
TAILINGS
MINERAL RESOURCE ESTIMATE of the TAILINGS
AREA
The resource estimate for the tailings is 137,501 tonnes grading
0.67 g/t gold for 2,944 contained ounces of gold in the Indicated
category for all material in the tailings. A 10g/t cut on all
top assay values was applied. As the resource is for a tailings
deposition no cut-off grade was applied to the reported resource,
as any practical recovery will require processing of all material.
Results at various gold cut-off grades for the low grade stockpile
are tabulated below:
MINERAL RESOURCE TABLE of the TAILINGS AREA
Cut-off Au
g/t |
Tonnes |
Au (g/t) |
Grade (g/t)
(Contained) |
Grams
(Contained) |
Ozs
(Contained) |
<0.1 |
137,501 |
0.67 |
91,545 |
2,944 |
0.2 |
137,190 |
0.67 |
91,489 |
2,942 |
0.3 |
130,454 |
0.69 |
89,701 |
2,884 |
0.5 |
78,150 |
0.87 |
68,326 |
2,197 |
As with the waste stockpile Laurion commissioned
a comprehensive program to accurately determine the location and
volume of the tailings and to sample the tailings pile. An
overburden drill was used to acquire representative samples
throughout the tailings containment area. This information was used
to calculate a 43-101 compliant resource estimate.
The survey of the tailings area was carried out
by TBT Engineering Consulting Group ("TBTE") of Thunder Bay, using a Trimble R8 RTK GPS with
an accuracy of approximately 1 cm. The overburden drilling was also
carried out by TBTE with hole locations determined using the
Trimble R8 RTK GPS. Holes were planned on a diamond grid with 20
metre hole spacing. A total of 93 drill collars were spotted and 87
were drilled. Six holes were not drilled as they appeared to be off
the tailing area, or were inaccessible. A total of 376 samples were
collected, ranging from 0.10 metres to 1.10 metres, with an average
thickness of 0.42 metres. Tailings thickness intersected in the
drilling ranged from 0.60 metres to 3.90 metres. Most drill holes
penetrated through the tailings into the underlying organics, which
were also sampled.
Sampling of the overburden drilling was carried
out by TBTE with supervision by GeoVector. The samples were sent
Actlabs and they were analyzed by fire assay with AA finish. Any
high grade samples over 3000 ppb gold were further treated to fire
assay with gravimetric finish to determine a final gold grade.
Individual assay results ranged from nil Au to 21.50 g/t Au. The Au
grade was consistently higher in the lower intervals of the
tailings intersections. Drill intersections through the total
tailings thickness ranged from a low of 0.13 g/t over 1.0 metre to
9.65 g/t over 0.90 metres. Some of the higher grade drill hole
intersections were:
Hole Number |
From (m) |
To (m) |
Average Grade (Au g/t) |
BH64 |
0 |
0.90 |
9.65 |
BH76 |
0 |
0.60 |
6.47 |
BH73 |
0 |
1.20 |
2.99 |
BH74 |
0 |
1.10 |
2.30 |
BH84 |
0 |
1.70 |
2.28 |
These assay results and the survey data were
incorporated into a mineral resource estimate by GeoVector.
All samples from the 2010 waste pile program
were delivered by GeoVector Management Inc. personnel to the
Activation Laboratories ("Actlabs") facility in Geraldton. Actlabs is an ISO/IEC 17025
accredited analytical laboratory.
The mineral resource model was constructed in
Gemcom GEMS 6.4. The model is based on the survey data. A block
model with the origin at 444120E, 5511110N, 330m elevation was
constructed using 4 x 4 x 0.3 metre blocks in the x, y, and z
direction respectively. Grades for gold were interpolated into the
blocks by the inverse distance squared method using between two and
twelve composites to generate block grades. The size of the search
ellipse was set at 40 x 40 x 5 metres in the X, Y, Z direction
respectively for the indicated resource. The Principal and
Intermediate azimuths create a circular ellipse and the Principal
dip is oriented at 0°. An average SG value of 2.20, appropriate for
compacted ground tailings, was applied to all blocks within the
block model.
METALLURGICAL TEST RESULTS of TAILINGS
SAMPLES
Following the assaying of the tailings samples composite samples
were prepared from all remaining from the remaining sample reject.
The composites formed two populations, the sand to silt size
tailings, and the organic layer beneath the tailings. Averaged
assayed head grade for the tailing sample was 0.42 g/t gold. The
organics had an averaged assayed head grade of 1.57 g/t gold. The
organics samples required ashing prior to metallurgical testing to
reduce preg-robbing effects of the organic carbon and the ashed
organics had an averaged assayed head grade of 3.31 g/t gold.
The tests included gravity concentration using a
Knelson Concentrator and cyanidation. The gravity concentration
tests indicated that the ash samples were not amenable to gravity
concentration (less than 1% recovery). Likewise the gravity
tests on the tailings sample using the Knelson Concentrator had
relatively poor results with only recovered 22% of the gold.
The cyanidation tests indicated that a
tailings/ash composite had dissolution of over 96% of the gold and
required leaching time of less than 12 hours. The tailings alone
required longer (48 hours) leaching times and the maximum
dissolution achieved was 67-72%. Test results indicate that the low
grade tailings resource would be amenable to gold recovery using
cyanide. In all cases the cyanide and lime consumptions were fairly
low.
About the Ishkoday Project
The Ishkoday reported a historical production of 73,322 ounces
of gold and 15,929 ounces of silver from 145,123 tons taken
primarily from # 3 Vein during 1936 to 1942, but also from the # 10
Vein and the M Vein that were encountered at the lower depths of
the mine in the later years of mine life. During mine life the mine
development material was hand sorted at surface and stockpiled next
to the mine shaft and mill locations. The higher grade quartz veins
were milled with tailings placed in a natural depression next to
the mill site. Both the low grade stockpile and tailings areas have
been largely undisturbed since the mine closed during World War II
due to manpower shortages.
QUALIFIED PERSON
Joe Campbell, B.Sc. P. Geo., a
director of Laurion Mineral Exploration Inc., is the Qualified
Person, as defined by NI 43-101, for the Ishkoday Project and has
reviewed the technical information in this release.
The Indicated mineral resource estimate has been
prepared in compliance with the standards of NI 43-101 by Dr.
A. Armitage, P. Geo. Mr. Armitage is
independent of the Corporation under NI 43-101. A NI 43-101 report
will be finalized and filed on SEDAR within 45 days of the date of
this news release.
About Laurion Minerals Exploration
Inc.
Laurion Mineral Exploration Inc. is a junior
mining company focusing on the upside of its 100%-owned Ishkoday
Property, a high impact VMS project, having a primary focus on gold
and base metals.
With proven ability to develop early stage projects and create
shareholder value by monetizing its discoveries and assets, Laurion
has realized a total of $6.35 million
in the last two years from monetization of its assets.
The Corporation's current emphasis is on resource development at
the Ishkoday Property, located in Beardmore, Ontario, approximately 220 km
northeast of Thunder Bay.
Neither TSX Venture Exchange nor its
Regulation Services Provider (as that term is defined in the
policies of the TSX Venture Exchange) accepts responsibility for
the adequacy or accuracy of this release.
This news release includes certain
forward-looking statements concerning the future performance of
Laurion's business, operations and financial performance and
condition, as well as management's objectives, strategies, beliefs
and intentions. Such statements include, but are not limited to,
statements concerning the approval of Laurion's application to
trade its common shares over the facilities of the OTCQX and the
commencement of such trading. Forward-looking statements are
frequently identified by such words as "may", "will", "plan",
"expect", "anticipate", "estimate", "intend" and similar words
referring to future events and results. Forward-looking statements
are based on the current opinions and expectations of management.
All forward-looking information is inherently uncertain and subject
to a variety of assumptions, risks and uncertainties, including the
speculative nature of mineral exploration and development,
fluctuating commodity prices, competitive risks and the
availability of financing, as described in more detail in our
recent securities filings available at www.sedar.com. Actual events
or results may differ materially from those projected in the
forward-looking statements and Laurion cautions against placing
undue reliance thereon. Laurion and its management assume no
obligation to revise or update these forward looking
statements.
SOURCE Laurion Mineral Exploration Inc.