Kaminak Validates Heap Leach Process at Coffee Gold Project
Oxide Gold Recoveries of Greater Than 90% in 40 Days on 1 Inch
Crushed Material
VANCOUVER, BRITISH COLUMBIA--(Marketwired - Dec 2, 2013) -
Kaminak Gold Corporation (TSX-VENTURE:KAM) today announced the
results of the first phase of a comprehensive metallurgical test
work program at the Coffee Gold Project, Yukon, that will provide
process input data for the updated NI 43-101 Mineral Resource
Estimate scheduled for completion in the 1st Quarter of 2014, which
will in turn lead into the initiation of a Preliminary Economic
Assessment ('PEA'). The primary objectives of the 2013
metallurgical program were to test the potential for heap leach
processing of Oxide and Transitional facies at Supremo and Latte,
two of the largest deposits discovered to date at Coffee, at
variable crush sizes (0.5", 1.0" and 6") and to establish
representative gold recovery rates from cyanide soluble gold
assaying for Oxide, Transitional and Sulphide facies mineralization
at various depth profiles across the Coffee deposits.
Highlights from this work include:
- Column leach gold recoveries of 90% to 92% on 1"crushed
material from drill core composites of representative Oxide
material from each of Latte and Supremo were achieved within 40
days.
- All of the samples leached very rapidly with 81.6% and 81.0%
gold recovery after ten days leaching of the 1 inch Oxide crushed
material from Latte and Supremo respectively.
- Column leach test work was conducted under simulated cold
climate conditions by Kappes, Cassiday and Associates, industry
leading experts in heap leach processing. Agglomeration was not
required and low reagent consumption was reported.
- Bottle roll gold recoveries were not substantially increased
compared to the column leach tests indicating that heap leaching is
a more attractive option than agitation leaching at this stage of
the project.
- Results from cyanide soluble gold assaying of representative
samples from throughout the Coffee deposit compare favorably with
results from column leach testing of the same sample set (see Table
4) and is being considered as a potentially quantitative method for
measuring recoverable gold across all mineralized zones and to
depth.
- A preliminary analysis of cyanide soluble data returned from
the testing of historical drilling pulps increased the proportion
of the resource classified as Oxide at Supremo from a previous
visual estimate of 55% to almost 70%, with a further 20% reporting
as Upper Transitional Facies. The quantity of Latte Oxide Facies is
similar to the previous visual estimation of 25%, with a further
15% reporting as Upper Transitional Facies.
Fred Lightner, Director Mine Development, stated:
"The metallurgical testing results illustrate the
amenability of the Coffee deposit to heap leaching, which is
typically lower in capital and operating costs than other gold
recovery methods. The rapid leaching kinetics, low reagent
consumption, lack of agglomeration and the excellent oxide
recoveries are most encouraging especially when combined with a
requirement for minimal crushing. The results of our 2013
metallurgical program will provide valuable input for the
Preliminary Economic Assessment."
Eira Thomas, Kaminak President and CEO commented:
"This is an important milestone for our project. Not only
have we demonstrated that heap leaching represents a viable gold
recovery option at Coffee, the cyanide soluble leach assay data
will allow us to better map and quantify recoverable gold in the
resource block model, which is in the process of being updated,
incorporating the results from more than 55,000 metres of new
drilling completed in 2013. Kaminak expects to complete and
announce an updated NI 43-101 Mineral Resource Estimate early in
Q1, 2014".
2013 Coffee Gold Project Metallurgical Test Work Program
Results of the column leach tests conducted by Kappes, Cassiday
and Associates ("KCA") are summarized below in Table 1.
Table 1 Simulated Cold Climate (4 Degrees Centigrade)
Column Leach Test Results |
Sample Description |
Crush Size* inches |
Head Grade g/t Au |
Extracted Grade g/t Au |
Gold Recovery % |
Days Leached |
Consumption NaCN kg/t |
Supremo Oxide |
1.0 |
1.57 |
1.46 |
92% |
40 |
0.17 |
Supremo Oxide |
0.5 |
1.44 |
1.34 |
94% |
40 |
0.28 |
Supremo Oxide |
0.5 |
1.55 |
1.47 |
95% |
42 |
0.52 |
Supremo Upper Transition |
0.5 |
1.49 |
1.08 |
73% |
40 |
0.31 |
Supremo Lower Transition |
0.5 |
1.67 |
0.80 |
48% |
40 |
0.38 |
Latte Oxide |
1.0 |
1.62 |
1.46 |
90% |
40 |
0.19 |
Latte Oxide |
0.5 |
1.54 |
1.38 |
90% |
40 |
0.27 |
Latte Upper Transition |
0.5 |
1.54 |
0.72 |
47% |
40 |
0.46 |
Latte Lower Transition |
0.5 |
1.42 |
0.41 |
29% |
40 |
0.64 |
Latte Sulphide |
0.5 |
2.37 |
0.13 |
5% |
42 |
0.46 |
*Drill core composites crushed to 31.5 mm (80% passing 1 inch)
and 16 mm (80% passing 1/2 inch) |
**22 degree centigrade test performed at ambient lab
temperature |
In the oxide samples, the recoveries of 90% and above were
obtained at both a crush size of 0.5 and 1 inch material.
Additional test work is currently ongoing to investigate a nominal
6 inch crush size (80% passing 150 mm) for the oxide mineralization
at both Supremo and Latte.
Preliminary test work reported no percolation problems;
therefore, the use of cement agglomeration was not required. The
column leach tests were performed at a temperature of 4 degrees
Centigrade to simulate cold climate leaching, with the exception of
one test at ambient lab temperature (22 degrees C) as a test
control. The gold recovery difference between ambient and cold
climate temperature is negligible at 1% (95% versus 94% gold
recovery respectively).
All of the samples leached very rapidly with 81.0% and 81.6%
gold recovery from Supremo and Latte respectively within ten days
leaching of the 1 inch Oxide columns. Low cyanide consumption was
reported from all leach columns.
To view Figure 1, visit the following link:
http://media3.marketwire.com/docs/KAM_1201_fig1.jpg
Further images from the 2013 metallurgical test work program can
be found on the Kaminak website:
http://kaminak.com/projects/sections_and_maps/metallurgical_data/2013
Comparative Bottle Roll Test Work
Results from bottle roll test work undertaken on splits of the
same composites utilized for column leaching are detailed below in
Table 2. The bottle roll leach tests are somewhat comparable to the
column leach tests. By using a fine grind, recoveries were not
substantially increased over the column leach tests, indicating
that heap leaching will most probably be economically more
attractive than agitation leaching.
Table 2 Results of Bottle Roll Leach Tests |
Description |
Target p80 Size mm |
Head Grade g/t Au |
Extracted Grade g/t Au |
Gold Recovery % |
Leach Time hours |
Supremo Oxide |
0.075 |
1.44 |
1.36 |
94% |
96 |
Supremo Upper Transition |
0.075 |
1.45 |
1.13 |
78% |
96 |
Supremo Lower Transition |
0.075 |
1.64 |
0.87 |
53% |
96 |
Latte Oxide |
0.075 |
1.57 |
1.45 |
92% |
96 |
Latte Upper Transition |
0.075 |
1.37 |
0.70 |
51% |
96 |
Latte Lower Transition |
0.075 |
1.46 |
0.55 |
38% |
96 |
Latte Sulphide |
0.075 |
2.46 |
0.32 |
13% |
96 |
Sample Composite Selection for the 2013 Metallurgical Test
Program
All of the samples used for the column leach tests were
composited from drill core consisting of a wide distribution of
different drill holes and individual intervals to give a
representative sample of each deposit area. Composites were
selected at a head grade (see Table 1) close to the global average
grade of 1.56g/t Au (base case cut-off) for the 2012 NI 43-101
Coffee Inferred Mineral Resource Estimate. Details of the
metallurgical test work composite selection are provided in Table
3.
Table 3 Metallurgical Composite Selection |
Sample Description |
Avg. % Fresh Rock |
|
Sample Type |
Core length (m) |
Number of samples |
Number of holes sampled |
Supremo, Oxide |
3 |
|
1/2 core |
150 |
151 |
16 |
Supremo, Upper Transition |
27 |
|
1/4 core |
127 |
130 |
12 |
Supremo, Lower Transition |
71 |
|
1/4 core |
112 |
112 |
8 |
Latte, Oxide |
2 |
|
1/2 core |
127 |
128 |
15 |
Latte, Upper Transition |
35 |
|
1/4 core |
101 |
97 |
8 |
Latte, Lower Transition |
71 |
|
1/4 core |
95.5 |
96 |
7 |
Latte, Sulphide |
99 |
|
1/4 core |
73 |
72 |
8 |
Cyanide Soluble Gold Test Work
Categorization of oxidation facies has in the past been
undertaken via visual estimation of the proportion of Oxide and
Sulphide, followed by the manual interpretation of surfaces and the
assignment of oxide facies within the resource block model
dependent on whether a block is above or below a certain oxidation
surface. The oxidation profile at Coffee is variable, being
controlled by the percolation of meteoric water from surface
downwards and along the mineralized structures. Thus, the manual
interpretation method is unlikely to be detailed enough to
accurately assess the quantity and distribution of oxidation
facies. In particular, the internal variability within Transitional
facies material, which represents a continuum from 5% to 95%
oxidized material, is not able to be modelled via the visual
method. Presently, the Transitional facies is simply divided into
an 'Upper' and 'Lower' zone based on ≥50% oxidized material and
≤50% oxidized material respectively.
In order to better evaluate the amenability and variability of
Transitional material to metallurgical cyanide leach recovery, over
8,000 samples representing 70% of all samples above a fire assay
value of 0.3g/t Au within mineralized intercepts drilled from the
initial drilling year of 2010 up to and including 2013, have been
subjected to a cyanide soluble assay. The cyanide soluble assays
were performed by ALS Laboratories (Au-AA13 method).
The difference between the cyanide soluble assay and the
original fire assay, on an individual assay by assay basis, or
across composites made up of equivalent samples, may be utilized to
provide an indication of the gold within the sample that is
amenable to cyanide leach. By extension, it also indicates the
amount of oxidation of the sample. The cyanide soluble proxy gold
recovery is the percentage of the fire assay value actually
reporting to the leach solution.
A comparison of the column leach test recoveries at the 0.5 inch
crush size from the KCA testing program, and the cyanide soluble
assays from the same samples as used in the testing composites, is
presented in Table 4 below.
Table 4 Cyanide soluble gold recovery versus column
leach gold recovery |
Sample Description |
Column Recovery, % Au |
Cyanide Soluble Recovery |
Ratio of Column Recovery to Cyanide Soluble Recovery |
Supremo, Oxide |
94% |
98.4% |
0.96 |
Supremo, Upper Transition |
73% |
78.2% |
0.93 |
Supremo, Lower Transition |
48% |
51.2% |
0.94 |
Latte, Oxide |
90% |
91.2% |
0.99 |
Latte, Upper Transition |
47% |
46.5% |
1.00 |
Latte, Lower Transition |
29% |
32.5% |
0.89 |
The strong correlation of the cyanide soluble recovery and the
actual column leach test recovery indicates that cyanide soluble
recovery may be a reliable method to map the metallurgical recovery
throughout the Oxide, Transitional and Sulphide zones of the Coffee
Deposit. Work is ongoing to test the potential for applying this
methodology in future iterations of the Coffee Mineral Resource
Estimate.
The oxidation profile at Coffee is generally deep, sometimes in
excess of 300 meters. Furthermore, all of the mineralization at
Coffee currently remains open to depth. From preliminary
mineralogical examination of Transitional material at Supremo and
Latte, it appears that remnant sulphide mineralization within the
Supremo Transitional material has been more efficiently oxidized,
and hence, gold extractions from Transitional material at Supremo
are comparatively better than those at Latte.
A preliminary comparison of the cyanide soluble assay data
against the 2012 NI 43-101 Coffee Inferred Mineral Resource
Estimate suggests an increase in the proportion of the Supremo
deposit classified as Oxide facies, from a previous visual estimate
of 55% to close to 70%, and with a further 20% reporting as Upper
Transitional facies. The preliminary analysis suggests the
proportion of the Latte deposit classified as Oxide facies is
similar to the previously modelled 25%, with a further 15%
reporting as Upper Transitional Facies.
Sulphide Flotation Testing
In addition to the cyanide leaching test program, KCA also
conducted four preliminary rougher flotation tests on the Latte
Sulphide sample. Although reagents, grind size and flotation time
have not been optimized, gold recoveries varied from 58% to 72% of
the gold reporting to a rougher flotation concentrate. Additional
work will depend on the future delineation and quantification of
sulphide resources.
Kaminak's disclosure of metallurgical data in this press release
has been reviewed and approved by Fred Lightner, P.Eng., Director
Mine Development of Kaminak Gold Corporation, who serves as a
Qualified Person under the definition of National Instrument
43-101. Disclosure of additional technical or scientific
information in this press release has been reviewed and approved by
Tim Smith, P.Geo., Vice President Exploration of Kaminak Gold
Corporation, who serves as a Qualified Person under the definition
of National Instrument 43-101.
On behalf of the Board of Directors of Kaminak
Eira Thomas, President and CEO
Kaminak Gold Corporation
For further information about Kaminak Gold Corporation or this
news release, please visit our website at www.kaminak.com.
Neither the 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.
Caution Concerning Forward-Looking Statements
Certain disclosures in this release, including management's
assessment of the future potential of the Coffee Project and future
exploration programs, constitute forward-looking statements that
are subject to numerous risks, uncertainties and other factors
relating to Kaminak's operations as a mineral exploration company
that may cause future results to differ materially from those
expressed or implied in such forward-looking statements, including
risks as to the completion of the plans and projects. Readers are
cautioned not to place undue reliance on forward-looking
statements. Except as required by law, Kaminak expressly disclaims
any intention or obligation to update or revise any forward-looking
statements, whether as a result of new information, future events,
or otherwise.
The Company has not made a production decision and the Company's
strategic plan to develop a stand-alone heap leach operation is
subject to the results of its Feasibility Study. Further, if and
when the Company makes any production decision, it will disclose
the basis of such decision in accordance with the requirements of
National Instrument 43-101 Standards of Disclosure for Mineral
Projects ("NI 43-101").
Cautionary Note concerning estimates of Inferred Resources:
This news release uses the term "inferred resources". Inferred
resources have a great amount of uncertainty as to their existence,
and great uncertainty as to their economic and legal feasibility.
It cannot be assumed that all or any part of an Inferred Mineral
Resource will ever be upgraded to a higher category. Under Canadian
rules, estimates of Inferred Resources may not form the basis of
feasibility or other economic studies. Kaminak advises U.S.
investors that while this term is recognized and required by
Canadian regulations, the U.S. Securities and Exchange Commission
do not recognize it. U.S. investors are cautioned not to assume
that part or all of an inferred resource exists, or is economically
or legally minable.
Kaminak Gold CorporationTony RedaVice President of Corporate
DevelopmentToll Free: 1.888.331.2269 or Direct:
604.646.4534604.646.4526info@kaminak.comwww.kaminak.com
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