Discovery Silver Corp. (TSX-V: DSV, OTCQX: DSVSF)
(“Discovery” or the “Company”) is pleased to announce results from
its metallurgical test program on representative samples from the
Cordero deposit. This program represents the most comprehensive
test work completed on Cordero to date. Tests were completed at the
Blue Coast Research Ltd. (“Blue Coast”) laboratory located in
Parksville, BC, Canada. Highlights from the test work include:
Sulphide flotation test
work
- Silver
recoveries of 80-89%, lead recoveries of 83-91% and zinc recoveries
of 81-90% from locked cycle tests.
- Test work
completed on all major rock types at Cordero.
- Higher
recoveries were achieved at coarser grind sizes.
- Saleable
concentrate grades confirmed and levels of penalty elements for
concentrates were insignificant.
Oxide & transition cyanidation test
work
- Silver
recoveries of 54-80% & gold recoveries of 61-75% at coarse
crush / grind sizes from coarse bottle roll testing.
- Results
represent the first indication that a heap leach on the oxide &
transition material at Cordero may be economic.
- Follow-up column
leach test work is currently underway.
Taj Singh, President and CEO, states: “The
results from this metallurgical test work program represent a major
de-risking step for Cordero. All major rock types hosting sulphide
ore returned excellent recoveries via conventional flotation
processes to generate clean, highly saleable concentrates.
In addition, there were two new positive
developments that also emerged from the test work. Firstly, the
highest recoveries were achieved at coarse grind sizes of 175-200
microns, which should help reduce capital and operating costs for
the project. Secondly, mineralized oxide and mixed oxide-sulphide
(transition) “pre-strip” material that sits at surface above the
large sulphide ore body responded very well to cyanidation
introducing the potential to heap leach this material at the start
of the mine life. Both developments should have a positive impact
on the overall project economics that will be outlined in our PEA
due for release next quarter.”
SULPHIDE FLOTATION:
Differential lead-zinc flotation test work was
completed on medium-grade sulphide samples representing the four
different rock types at Cordero. Samples were sourced from across
the deposit in both the North and South Corridor. Test work
confirmed excellent recoveries for silver, lead and zinc via
conventional flotation processes to generate separate lead and zinc
concentrates. Saleable concentrate grades were achieved and levels
of penalty elements for both concentrates were insignificant.
Significantly, close to 90% of the recovered silver reports to the
lead concentrate where the highest payabilities are applicable.
Test |
Rock Type |
Head Grade |
Lead + Zinc Circuit |
Recovery to Concentrate |
Ag |
Au |
Pb |
Zn |
AgEq |
Ag |
Au |
Pb |
Zn |
(g/t) |
(g/t) |
(%) |
(%) |
(g/t) |
(%) |
(%) |
(%) |
(%) |
LCT-1 |
Breccia - Volcanic |
35 |
0.23 |
0.55 |
0.83 |
108 |
89 |
19 |
91 |
90 |
LCT-2 |
Breccia - Sedimentary |
37 |
0.21 |
0.46 |
0.55 |
93 |
84 |
16 |
89 |
86 |
LCT-3 |
Volcanic |
34 |
0.11 |
0.43 |
0.67 |
86 |
83 |
19 |
85 |
81 |
LCT-4 |
Sedimentary |
27 |
0.12 |
0.43 |
0.73 |
82 |
80 |
18 |
83 |
89 |
Sample selection:
- Samples of the
four major rock types were sourced from locations spatially
throughout the entire deposit including the Pozo de Plata and NE
Extension zones in the North Corridor and from along the central
and southwest parts of the South Corridor.
- Given the low
variability in the rougher test results based on sample location
master composites were created based on the four rock types for
cleaner and locked cycle tests.
Comminution:
- Bond abrasion
index (Ai) ranged from 0.142 to 0.351 g for each rock type; this
corresponds to a categorization of Slightly Abrasive to
Medium.
- Bond ball work
index (BWI) ranged from 17.6 to 19.5 kWh/tonne (metric); this
corresponds to a categorization of a Hard ore.
- Higher
recoveries were achieved at coarser grind sizes; a targeted coarse
grind size of 80% passing 175-200 microns will be assumed for
process design purposes.
Locked cycle tests:
- Locked cycle
tests were completed on each of the four major rock types at a
targeted grind size of 200 microns.
- Excellent
recoveries were achieved for silver (80-89%), lead (83-91%) and
zinc (81-90%).
- Close to 90% of
silver reports to the lead concentrate - this is highly significant
to the potential economics of an operation at Cordero, as the
highest silver payability is received for silver in the lead
concentrate.
- Low recoveries
for gold were in-line with previous test work; the majority of gold
is associated with pyrite that gets rejected during the concentrate
cleaning process.
Test |
Lead Circuit |
Zinc Circuit |
Recovery to Conc. |
Concentrate Grade |
Recovery to Conc. |
Concentrate Grade |
Ag |
Au |
Pb |
Ag |
Au |
Pb |
Ag |
Au |
Zn |
Ag |
Au |
Zn |
(%) |
(%) |
(%) |
(g/t) |
(g/t) |
(%) |
(%) |
(%) |
(%) |
(g/t) |
(g/t) |
(%) |
LCT-1 |
79 |
13 |
91 |
2,923 |
3.1 |
53.0 |
11 |
7 |
90 |
237 |
1.0 |
46.3 |
LCT-2 |
75 |
12 |
89 |
3,774 |
3.4 |
55.7 |
9 |
4 |
86 |
397 |
0.9 |
54.6 |
LCT-3 |
70 |
13 |
85 |
3,318 |
1.9 |
50.1 |
13 |
6 |
81 |
400 |
0.7 |
50.9 |
LCT-4 |
70 |
13 |
83 |
2,886 |
2.3 |
54.0 |
10 |
5 |
89 |
213 |
0.4 |
51.4 |
Concentrate analysis:
- Saleable
concentrate grades for both lead and zinc concentrates were readily
achieved as highlighted in the table above
- Level of penalty
elements was low confirming excellent saleability of both
concentrates as outlined in the table below
Element |
Average Grade1 |
Penalty Threshold2 |
Lead Concentrate: |
As |
0.38% |
0.50% |
Sb |
0.54% |
0.50% |
Hg |
11 ppm |
100 ppm |
F |
50 ppm |
500 ppm |
Zinc Concentrate: |
As |
0.21% |
0.30% |
Fe |
8.87% |
8.00% |
Cd |
0.48% |
0.30% |
SiO2 |
1.32% |
3.50% |
Hg |
15 ppm |
100 ppm |
F+Cl |
300 ppm |
500 ppm |
Se |
22 ppm |
300 ppm |
Mn |
0.91% |
0.50% |
1Average grade was calculated as an arithmetic
average of the concentrates from the four locked cycle tests
2 Penalty thresholds vary between smelters; the
thresholds listed above are representative of common thresholds
typically applied on lead and zinc concentrates
Planned additional test
work:
- Testing of
low-grade sulphide material representative of potential stockpile
material recently commenced and is ongoing; results are expected to
be incorporated in the upcoming preliminary economic assessment
(“PEA”) of the Cordero project scheduled for completion in 4Q
2021
TESTWORK ON
OXIDE/TRANSITION:
Cyanidation test work was completed on the oxide
and mixed oxide-sulphide (“transition”) material at Cordero. The
oxide and transition material in aggregate represents approximately
5-10% of the total ore body. Test work consisted of coarse bottle
roll test work at different crush / grind sizes. Based on the
excellent results from these initial tests, column leach test work
commenced in July 2021 with McClelland Laboratories, Inc.
(“McClelland”) based in Reno, Nevada. This will be the first column
leach test work conducted on oxide and transition material and if
successful, it offers the potential that a commercial heap leach
operation could be included in the processing plan in the early
years of the project life. Such a heap leach operation would
recover silver and gold from “pre-strip” material that would
typically be regarded as waste rock. Preliminary results from the
column leach test work are expected to be received in 4Q 2021, in
time to be included in the upcoming PEA.
Coarse Bottle Roll tests:
- Oxide and
transition samples were selected from widespread locations in both
the North and South Corridor. The level of oxidation in the
transition samples varied from 20% to 80%.
- Tests were
completed at different crush / grind sizes on both oxide and
transition material.
- Results
confirmed the potential for oxide / transition material to be
recovered via heap leach processing.
Crush / Grind Size |
Material |
Head Grade |
Recoveries |
Ag |
Au |
Ag |
Au |
(g/t) |
(g/t) |
(%) |
(%) |
0.15 mm (150 microns) |
Oxide |
44 |
0.07 |
80 |
63 |
0.30 mm (300 microns) |
Oxide |
44 |
0.07 |
77 |
62 |
3.4 mm (1/8 in) |
Oxide |
44 |
0.07 |
65 |
61 |
6.7 mm (1/4 in) |
Oxide |
58 |
0.10 |
59 |
71 |
12.7 mm (1/2 in) |
Oxide |
44 |
0.07 |
54 |
61 |
6.7 mm (1/4 in) |
Transition |
52 |
0.07 |
63 |
75 |
12.7 mm (1/2 in) |
Transition |
52 |
0.07 |
54 |
72 |
1All crush and grind size test work was
completed by Blue Coast at a target NaCN dosage of 1.0 g/L except
for the ¼ inch oxide sample which was completed by McClelland at
NaCN dosages of 1.0 g/L and 2.0 g/L (the average of these two test
results is shown in the table)
Planned test work
- Agglomeration,
load-permeability and column leach test work has recently commenced
with McClelland;
- If results from
this test work are positive, a commercial heap leach operation will
be included in the upcoming PEA
About Discovery
Discovery’s flagship project is its 100%-owned
Cordero project, one of the few silver projects globally that
offers margin, size and scaleability. Cordero is located close to
infrastructure in a prolific mining belt in Chihuahua State,
Mexico, and is supported by an industry leading balance sheet with
over C$80 million available for aggressive exploration, resource
expansion and future development. Discovery was a recipient of the
2020 TSX Venture 50 award and the 2021 OTCQX Best 50
award. On Behalf of the Board of Directors,
Taj Singh, M.Eng, P.Eng, CPA, President, Chief
Executive Officer and Director
For further information contact:
Forbes Gemmell, CFAVP Corporate
Development & Investor RelationsPhone: 416-613-9410Email:
forbes.gemmell@discoverysilver.comWebsite:
www.discoverysilver.com
Qualified
PersonThe scientific and technical content of this
press release was reviewed and approved by Tommaso Roberto Raponi,
P.Eng. who is a "Qualified Person" as defined by National
Instrument 43-101 - Standards of Disclosure for Mineral Projects
("NI 43-101"). Data verification consisted of ensuring that the
samples selected came from within the area where the Mineral
Resource was estimated. The QP checked that the sampling protocol
used was applicable for the planned test work. In the QP’s opinion,
the test work conducted was completed by a reputable metallurgical
testing facility and used industry-standard methods. Mr. Raponi is
a consultant to Ausenco Engineering Canada Inc. (“Ausenco”) and is
considered to be “independent” of Discovery for purposes of section
1.5 of NI 43-101.
About Ausenco
Ausenco is a global diversified engineering,
construction and project management company providing consulting,
project delivery and asset management solutions to the resources,
energy and infrastructure sectors. Ausenco’s experience in gold
projects ranges from conceptual, pre-feasibility and feasibility
studies for new project developments to project execution with EPCM
and EPC delivery.
About Blue Coast
Blue Coast, founded in 2009, owns and operates a
12,000 square-foot laboratory in Parksville, BC, Canada, and has a
team of minerals engineers, scientists and technicians with
experience that spans decades. Blue Coast provides high-quality
metallurgical testing, analytical services, flowsheet development,
consulting and operational support and are a well-known and trusted
partner in the global minerals industry.
TECHNICAL NOTES & FORWARD-LOOKING
STATEMENTS:
The most recent technical report for the Cordero
Project is the 2018 Preliminary Economic Assessment (PEA) authored
by M3 Engineering and Technology Corp and includes the most recent
resource estimate, completed by Independent Mining Consultants,
Inc. It is available on Discovery’s website and on SEDAR under
Levon Resources Ltd, a wholly owned subsidiary of Discovery.
Neither TSX Venture Exchange nor its Regulation Services
Provider (as that term is defined in policies of the TSX Venture
Exchange) accepts responsibility for the adequacy or accuracy of
this release.
This news release is not for distribution to United States
newswire services or for dissemination in the United States.
This news release does not constitute an offer
to sell or a solicitation of an offer to buy nor shall there be any
sale of any of the securities in any jurisdiction in which such
offer, solicitation or sale would be unlawful, including any of the
securities in the United States of America. The securities have not
been and will not be registered under the United States Securities
Act of 1933, as amended (the “1933 Act”) or any state securities
laws and may not be offered or sold within the United States or to,
or for account or benefit of, U.S. Persons (as defined in
Regulation S under the 1933 Act) unless registered under the 1933
Act and applicable state securities laws, or an exemption from such
registration requirements is available.
Cautionary Note Regarding Forward-Looking
Statements
This news release may include forward-looking
statements that are subject to inherent risks and uncertainties.
All statements within this news release, other than statements of
historical fact, are to be considered forward looking. Although
Discovery believes the expectations expressed in such
forward-looking statements are based on reasonable assumptions,
such statements are not guarantees of future performance and actual
results or developments may differ materially from those described
in forward-looking statements. Factors that could cause actual
results to differ materially from those described in
forward-looking statements include fluctuations in market prices,
including metal prices, continued availability of capital and
financing, and general economic, market or business conditions.
There can be no assurances that such statements will prove accurate
and, therefore, readers are advised to rely on their own evaluation
of such uncertainties. There can be no assurance that the Private
Placement will close on the announced terms. Discovery does not
assume any obligation to update any forward-looking statements
except as required under applicable laws.
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