Western Exploration Reports Positive Gravel Creek Metallurgical Results, Including Gold Recovery of 94.8% to Combined Gravity and Flotation Concentrate
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Figure 1: Location of 2023 PQ Oriented core holes at
Highlights from the work include:
- Locked-cycle flotation tests indicate recoveries of 94.8% for gold and 89.8% for silver in a combined gravity and flotation concentrate.
- The combined gravity and flotation concentrate were 10.9% of the feed weight and averaged 57.1 g/t Au, 1,725 g/t Ag.
- The flotation concentrate averaged 29.1% sulphide sulphur.
- Gravity concentration before rougher flotation concentration (from the gravity tailings) recovered 22.4% of the Gold and 4.4% of the silver in 0.16% of the total feed weight with a gold grade of 920 g/t and a silver grade of 5,750 g/t.
2024 Flotation Metallurgy Sample Locations
Flotation test work was conducted on a gold and silver bearing diamond drill composite from core holes WG456 and WG457, drilled in 2023 in the
-
Hole WG456, located 250 meters northeast of the
Gravel Creek resource area, reported individual assays up to 34.9 g/t Au and 2800.0 g/t Ag as reported in a Company news release datedNovember 21, 2023 . -
Hole WG457, located 140 meters northeast of the
Gravel Creek resource area, reported individual assays up to 257.0 g/t Au and 1655.0 g/t Ag as reported in a Company news release datedJanuary 8, 2024 . - The composite was comprised of sulphide mineralization collected from samples ranging in downhole depths of 316 meters to 731 meters in WG456 and WG457.
Flotation Program and Results
All test work was completed by
Composite assays showed that it contained 6.14 g/t Au, 206 g/t Ag and 2.71% sulphide sulphur. Cyanide shake analysis showed that the sample had cyanide soluble to fire assay ratios (CN/FA) of 53.4% for gold and 36.8% for silver. The composite contained negligible amounts (<0.1%) carbon. A preg-rob assay showed that it was not preg-robbing.
Initially, six rougher flotation tests were conducted at feed sizes ranging from 80%-150 micron to 80%-45 micron. A typical bulk sulphide flotation collector reagent suite was employed for all tests. Following grind optimization testing, a bulk rougher concentrate was produced and used for preliminary cleaner flotation testing. The objectives for the testing were to maximize gold and silver recovery and concentrate grades. Sulphide sulphur recoveries were also tracked during testing. Variability in flotation tail grade caused significant variability in flotation gold recoveries.
Flotation testing showed that the
Table 1. - Flotation Concentration Test Results, Test F-5, Gravel Creek Composite 4991-001, 80%-75-micron Feed Size |
||||||||||||||||||||||
Wt. |
Cum. Wt. |
Assay |
Au Distribution |
Ag Distribution |
S= Distribution |
|||||||||||||||||
Product |
% |
% |
Au g/t |
Ag g/t |
% S= |
% |
Cum. % |
% |
Cum. % |
% |
Cum. % |
|||||||||||
Ro. Conc. Stg. 1 (0-2 min) |
4.1 |
4.1 |
95.5 |
3,360 |
28.07 |
57.0 |
57.0 |
64.0 |
64.0 |
42.9 |
42.9 |
|||||||||||
Ro. Conc. Stg. 1 (2-5 min) |
2.3 |
6.4 |
54.1 |
1,480 |
28.96 |
18.1 |
75.1 |
15.8 |
79.8 |
24.8 |
67.7 |
|||||||||||
Ro. Conc. Stg. 2 |
2.3 |
8.7 |
47.4 |
1,010 |
22.17 |
15.8 |
90.9 |
10.8 |
90.6 |
19.0 |
86.7 |
|||||||||||
Ro. Conc. Stg. 3 |
0.9 |
9.6 |
22.2 |
546 |
12.73 |
2.9 |
93.8 |
2.3 |
92.9 |
4.3 |
91.0 |
|||||||||||
Ro. Conc. Stg. 4 |
0.6 |
10.2 |
12.4 |
306 |
7.42 |
1.1 |
94.9 |
0.9 |
93.8 |
1.7 |
92.7 |
|||||||||||
Ro. Conc. Stg. 5 |
0.4 |
10.6 |
7.0 |
206 |
3.81* |
0.4 |
95.3 |
0.4 |
94.2 |
0.6 |
93.3 |
|||||||||||
Ro. Tail |
89.4 |
100.0 |
0.36 |
14 |
0.20 |
4.7 |
100.0 |
5.8 |
100.0 |
6.7 |
100.0 |
|||||||||||
Composite |
100.0 |
|
6.87 |
215 |
2.68 |
100.0 |
|
100.0 |
|
100.0 |
|
|||||||||||
* Insufficient sample was available for sulphide assay. The average of the adjacent product grades was used. |
Preliminary cleaner flotation testing showed that it was possible to significantly increase concentrate grades by cleaning. Cleaner concentrate grades of as high as >70 g/t Au, >3,900 g/t Ag and 41% sulphide sulphur were achieved.
Regrinding the rougher concentrate for as much as 90 minutes resulted in production of a cleaner concentrate that was 3.2% of the ore weight, assayed 72.4 g/t Au, 3,920 g/t Ag and 41.07% sulphide sulphur and represented recoveries of 35.9% gold, 59.6% silver and 49.2% sulphide sulphur. The corresponding cleaner tail was another 7.4% of the feed weight, assayed 40.6 g/t Au, 898 g/t Ag and 16.04% sulphide sulphur and represented additional recoveries of 46.5% gold, 31.5% silver and 44.4% sulphide sulphur, Table 2.
Table 2. - Rougher/Cleaner Flotation Concentration Test Results, Gravel Creek Composite 4991-001, 4991 F-6 Rougher Concentrate, 90 min Regrind of Ro. Conc. |
||||||||||||||||||||||
|
Wt. |
|
Cum. Wt. |
|
Assay |
|
Au Distribution |
|
Ag Distribution |
|
S= Distribution |
|||||||||||
Product |
% |
|
% |
|
Au g/t |
|
Ag g/t |
|
% S= |
|
% |
|
Cum. % |
|
% |
|
Cum. % |
|
% |
|
Cum. % |
|
Cl. Conc. |
3.2 |
|
3.2 |
|
72.4 |
|
3,920 |
|
41.07 |
|
35.9 |
|
35.9 |
|
59.6 |
|
59.6 |
|
49.2 |
|
49.2 |
|
Cl. Tail |
7.4 |
|
10.6 |
|
40.6 |
|
898 |
|
16.04 |
|
46.5 |
|
82.4 |
|
31.5 |
|
91.1 |
|
44.4 |
|
93.6 |
|
Ro. Tail |
89.4 |
|
100.0 |
|
1.27 |
|
21 |
|
0.19 |
|
17.6 |
|
100.0 |
|
8.9 |
|
100.0 |
|
6.4 |
|
100.0 |
|
Composite |
100.0 |
|
|
|
6.46 |
|
211 |
|
2.67 |
|
100.0 |
|
|
|
100.0 |
|
|
|
100.0 |
|
|
A gravity concentration test was conducted on tailings from one of the flotation tests to evaluate causes for variability in flotation tail grade. Results showed that most (77%) of the gold contained in the flotation rougher tail sample was gravity recoverable. The gravity concentrate produced was 0.07% of the flotation tail weight, assayed 2,250 g/t Au and represented 77.0% of the gold contained in the flotation tailing.
Follow up locked-cycle flotation test work was conducted at an 80%-150 micron grind size on gravity tails generated from the sample composite. Test results showed that the combined gravity and flotation concentrate was 10.9% of the feed weight, assayed 57.1 g/t Au and 1,725 g/t Ag. Recoveries reporting to this combined concentrate were 94.8% gold and 89.8% silver of the values contained in the whole feed. The combined concentrate described above included a gravity cleaner concentrate and flotation rougher concentrate (from locked-cycle testing on the gravity tailing). The gravity concentrate was 0.16% of the feed weight, assayed 920 g/t Au and 5,750 g/t Ag and represented gold and silver recoveries of 22.4% and 4.4% respectively. The gravity concentrate was not assayed for sulphide sulphur. The flotation concentrate was 10.74% of the whole feed weight, assayed 44.3 g/t Au, 1,665 g/t Ag and 21.9% sulphide sulphur and represented gold and silver recoveries of 72.4% and 85.4% respectively of values contained in the whole feed weight.
Table 3. – Gravity/Flotation Test, Gravel Creek Composite 4991-001, 80%-212-micron (Gravity Test G-2)/80%-150 micron Regrind (Locked Cycle Flotation Test F-9, average of Cycles 5&6) |
||||||||||||||||||||||
Wt. |
Cum. Wt. |
Assay |
Au Distribution |
Ag Distribution |
S= Distribution |
|||||||||||||||||
Product |
% |
% |
Au g/t |
Ag g/t |
% S= |
% |
Cum. % |
% |
Cum. % |
% |
Cum. % |
|||||||||||
Grav. Cl. Conc. |
0.16 |
0.16 |
920 |
5750 |
N/A* |
22.4 |
22.4 |
4.4 |
4.4 |
N/A |
N/A |
|||||||||||
Flotation Ro. Conc. |
10.74 |
10.90 |
44.3 |
1665 |
21.9 |
72.4 |
94.8 |
85.4 |
89.8 |
95.3 |
95.3 |
|||||||||||
Flotation Ro. Tail |
89.10 |
100.00 |
0.38 |
24 |
0.13 |
5.2 |
100.0 |
10.2 |
100.0 |
4.7 |
100.0 |
|||||||||||
Composite |
100.00 |
|
6.56 |
209 |
2.46 |
100.0 |
|
100.0 |
|
100.0 |
|
|||||||||||
*N/A denotes Not Available |
About the
The 6,000-hectare
In addition, the
Table 4. Mineral resource estimates for the |
||||||||||||||
MINERAL RESOURCE(1) |
||||||||||||||
|
Indicated |
Inferred |
||||||||||||
|
Tonnes |
Au
|
Au
|
Ag
|
Ag
|
AuEq
|
AuEq
|
Tonnes |
Au
|
Au
|
Ag
|
Ag
|
AuEq
|
AuEq
|
|
12,922,000 |
0.98 |
407,000 |
- |
- |
0.98 |
407,000 |
4,999,000 |
0.73 |
118,000 |
- |
- |
0.73 |
118,000 |
Wood Gulch(3) |
- |
- |
- |
- |
- |
- |
- |
4,359,000 |
0.66 |
93,000 |
5.80 |
808,000 |
0.74 |
104,543 |
|
1,315,000 |
4.73 |
200,000 |
75.0 |
3,169,000 |
5.81 |
245,271 |
2,744,000 |
4.16 |
367,000 |
60.20 |
5,307,000 |
5.02 |
442,814 |
TOTAL |
14,237,000 |
1.33 |
607,000 |
75.0 |
3,169,000 |
1.43 |
652,271 |
12,102,000 |
1.48 |
578,000 |
15.74 |
6,115,000 |
1.71 |
665,357 |
Notes: | ||
(1) |
Au equivalent oz assumes |
|
(2) |
Pit constrained 0.2 g/t AuEq cutoff for oxide, 0.4 g/t Au cutoff for mixed and 1.4 g/t Au cutoff for unoxidized. |
|
(3) |
Pit constrained 0.2 g/t AuEq cutoff. |
|
(4) |
3.0 g/t Au cutoff. |
|
See "Cautionary Statements Regarding Estimates of Mineral Resources" below. |
About
Additional information regarding
Qualified Person Approval
The scientific and technical information in this news release has been reviewed and approved by
Quality Assurance / Quality Control
Exploration program design, Quality Assurance/Quality Control ("QA/QC") and the interpretation of results is performed by qualified persons employing a QA/QC program consistent with NI 43-101 and industry best practices. For
Metallurgical Test Work
Interval Preparation and Assay: A total of 28 drill interval samples, from the
The entire composite was stage crushed to just passing 1.7mm in size. The -1.7mm composite was thoroughly blended and split to obtain multiple 1.0 kg samples for testing and triplicate 0.25 kg samples for head assay.
The composite was assayed directly in triplicate, using conventional fire assay fusion procedures, to determine gold and silver content. A single cyanide shake analysis was conducted, with and without a “gold spike” leach solution (preg-rob test series).
Flotation Testing
A total of six rougher flotation tests were conducted on composite 4991-001, at feed sizes ranging from 80%-150µm to 80%-45µm, to evaluate response to flotation and to optimize flotation feed size. The tests were conducted using a bulk sulphide flotation reagent scheme, designed to maximize recoveries of sulphide minerals, gold and silver.
Initially, a scouter rougher flotation test was conducted on a 1 kg sample at an 80%-75µm feed size, to obtain preliminary information concerning response of the ore to flotation treatment. Based on those results, a series of three additional rougher flotation tests (1 kg each) were conducted at feed sizes of 80%-150µm, 80%-106µm and 80%-45µm to optimize feed size. Based on those test results, the 75µm feed size was selected for further testing. A kinetic rougher flotation test was conducted at the 75µm feed size, to establish the relationships between flotation time, mass pull, rougher concentrate grade and recovery. A bulk flotation test (16 kg) was conducted at the 75µm feed size to generate rougher concentrate for cleaner flotation testing. Cleaner flotation tests (3) were conducted on the resulting bulk rougher concentrate to evaluate the potential for increasing concentrate grade by regrinding and cleaner flotation.
The same reagent suite was used for all rougher flotation tests. Flotation was conducted using a
Flotation was conducted in 5 stages with incremental additions of 0.005 kg/mt ore of PAX (potassium amyl xanthate) and 0.010 kg/mt AERO 208 (dithiophosphate) collectors at each stage. Respective total addition of each reagent was 0.025 and 0.050 kg/mt ore. AEROFROTH 65 was used as frother. The pulp was floated at natural pH. For all rougher flotation tests, except for the kinetic test, the 5 stages of concentrate were combined into a rougher concentrate. Those rougher concentrates were dried, weighed and assayed directly to determine gold, silver and sulphide sulphur content.
The five staged rougher concentrate samples generated from the kinetic flotation test (F-5) were each dried, weighed and assayed separately for the same constituents.
In the case of the bulk (16 kg) rougher flotation test (F-6), rougher flotation was conducted in two 8 kg lots, using a larger flotation machine. The rougher concentrates produced from those two tests were combined, dried, weighed and split to obtain three 0.5 kg samples for cleaner flotation testing and 0.2 kg for assay. The combined rougher concentrate was assayed directly to determine gold, silver and sulphide sulphur content. The rougher tails from each 8 kg lot were dried, weighed and assayed separately, in triplicate to determine gold silver and sulphide sulphur content (one sulphide sulphur assay per 8 kg lot). Results presented for rougher flotation test F-6 are based on the average of assay results from the two 8 kg lots (designated F-6A and F-6B).
Cleaner flotation tests (3) were conducted on the rougher concentrate generated from the bulk flotation test (F-6). The tests were conducted on 0.5 kg splits of rougher concentrate after regrinds of 1 minute (polish grind), 45 minutes and 90 minutes. Cleaner flotation was conducted without additional collector or promoter. Frother was added as required. The resulting cleaner concentrates and cleaner tails were dried, weighed and assayed to determine gold, silver and sulphide sulphur content.
For additional information on the
Cautionary Statements Regarding Estimates of Mineral Resources
This news release uses the terms measured mineral resources, indicated mineral resources, and inferred mineral resources as a relative measure of the level of confidence in the resource estimate. Readers are cautioned that mineral resources are not mineral reserves and that the economic viability of mineral resources that are not mineral reserves has not been demonstrated. The mineral resource estimate disclosed in this news release may be materially affected by geology, environmental, permitting, legal, title, socio-political, marketing, or other relevant issues. It cannot be assumed that all or any part of the inferred mineral resources will ever be upgraded to the category of indicated mineral resource or measured mineral resource. The mineral resource estimate is classified in accordance with the
Inferred mineral resources have a great amount of uncertainty as to their existence and as to whether they can be mined legally or economically. On
Cautionary Note Regarding Forward-Looking Information
This news release may contain "forward-looking information" and "forward-looking statements" within the meaning of the applicable Canadian and
For additional information with respect to these and other factors and assumptions underlying the forward-looking statements and forward-looking information made in this news release concerning
Neither the
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Telephone: (775) 329-8119
Email: dmarud@westernexploration.com
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