Discovery Reports Exceptional Results from its Pre-Feasibility Study Metallurgical Test Program
Discovery Reports Exceptional Results from its Pre-Feasibility
Study Metallurgical Test Program
August 29 , 2022, Toronto, Ontario - Discovery Silver Corp. (TSX-V: DSV, OTCQX:
DSVSF) (“Discovery” or the “Company”) is pleased to announce results from its Pre-Feasibility
Study (“PFS”) metallurgical test program on representative samples from its Cordero project
(“Cordero” or “the Project”) located in Chihuahua State, Mexico. This program represents the
most comprehensive test work completed on Cordero to date. Highlights from the locked-cycle
flotation test work include:
• Silver recoveries of 94-98%, lead recoveries of 89-97% and zinc recoveries of 92-96% on
high grade samples of all major rock types.
• Silver recoveries of 83-92%, lead recoveries of 85-92% and zinc recoveries of 81-89% on
medium grade samples of blended rock types.
• O xide-sulphide blend testwork establish oxide-specific recoveries of ~60% for silver, ~40%
for lead and ~85% for zinc via flotation ; co-processing oxide mineralized material via
flotation eliminates the need for heap leach processing at Cordero.
• Test work overall confirmed higher recoveries than what was assumed in the 2021
Preliminary Economic Assessment (“PEA”).
• All tests were completed at a coarse grind size of p80 passing ~210 micron and
demonstrated significantly lower reagent consumption than assumed in the PEA.
• Saleable concentrate grades confirmed and levels of penalty elements for concentrates
were insignificant.
Tony Makuch, Interim CEO, states: “ Our PFS metallurgical test results demonstrate the
exceptional metallurgical properties of our Cordero deposit. Recoveries typically ranged from
85-95% at an extremely coarse grind size of ~2 10 micron. On average sulphide recoveries
came in higher than what was assumed in our PEA and were achieved at significantly reduced
reagent consumption highlighting the potential for reduced operating costs for our PFS.
“In addition, our first ever flotation testwork of an oxide-sulphide blend returned very positive
results with economic recoveries for oxide mineralization for silver, lead and zinc through
flotation. These results allow for the elimination of the heap leach circuit in our PFS; this will
streamline the crushing/grinding circuit, reduc e upfront capital expenditures and simplif y the
permitting process.”
NEWS RELEASE
PFS METALLURGICAL TEST PROGRAM
Summary: the PFS metallurgical test program was designed to supplement the detailed
metallurgical test program completed in 2021 and included the Company’s first ever testing of
rock type blends, high-grade samples (+100 g/t AgEq) and oxide-sulphide blends. Test work
was also focused on optimizing reagent usage. All test work was completed at a coarse grind
size of ~210 micron.
Results from the 14 locked cycle tests are summarized in the table below. Recoveries from
these tests were higher than the recoveries assumed in the 2021 PEA and were achieved at
lower reagent consumptions. Further details including recoveries broken out by concentrate
type and head grade vs recovery plots for both our PEA and PFS metallurgical test programs
can be found in the appendices. The testwork was conducted by Blue Coast Research Ltd.
(“Blue Coast”), an independent third party, with oversight from Libertas Metallurgy Ltd.
(“Libertas”) and Ausenco Engineering Canada Inc. (“Ausenco”).
Test Type Rock Type /
Sample Location
Head Grade Lead + Zinc Circuit
Recovery to Concentrate
Ag Pb Zn AgEq Ag Pb Zn
(g/t) (%) (%) (g/t) (%) (%) (%)
High-Grade
Breccia 252 3.8 2.6 462 97 96 93
Volcanic 71 1.9 5.1 319 98 97 92
Volcanic 46 0.9 2.1 151 94 93 96
Sedimentary 41 0.8 1.6 128 94 89 93
Rock Type
Blend
Starter Pit 37 0.6 0.6 76 92 92 89
NE Extension 29 0.5 0.7 70 90 90 84
South Corridor 33 0.4 0.8 76 83 85 85
Run of Mine 33 0.5 0.8 76 87 89 81
Low-Grade Volcanic 10 0.1 0.2 21 43 64 62
Breccia 30 0.3 0.1 44 76 87 64
10% Oxide
/ 90%
Sulphide
Blend
Starter Pit 40 0.5 0.5 76 86 84 89
NE Extension 29 0.5 0.6 66 87 86 88
South Corridor 33 0.4 0.7 71 81 80 88
Run of Mine 35 0.5 0.7 74 84 84 88
High-grade samples: four locked cycle tests were completed on high-grade samples (+100
g/t AgEq) of the major rock types. Recoveries averaged 95% for silver, 94% for lead and 94%
for zinc. These recoveries were on average approximately 7% higher than the recoveries for
the medium-grade samples (50-100 g/t AgEq) confirming a positive relationship between head
grade and recovery.
Rock type blends: four locked cycle tests were completed on a blend of the major rock types
at Cordero (volcanic, breccia & sedimentary rocks). The blend ratios were based on the
expected proportions of mill feed from different parts of the deposit. Three of the four tests
returned higher than expected recoveries confirming the potential for positive synergies
through blending of the different rock types. Further testwork will be completed on
understanding and quantifying these synergies in more detail as part of the Company’s
feasibility study test program.
Oxide-sulphide blends: four locked cycle tests of oxide-sulphide blends (~10% oxides / ~90%
sulphides) returned implied average recoveries for oxide mineralization through flotation of
approximately 60% for Ag, 40% for Pb and 85% for Zn. These recoveries can most likely be
attributed to the presence of sulphide mineralization (galena and sphalerite) in the oxide layer
as identified by preliminary mineralogical analysis.
Based on these results the PFS will assume blending of oxides with sulphides in the flotation
circuit. This is a very positive development as it will reduce upfront capital expenditures through
the complete elimination of the heap leach circuit as well as simplify the process design through
reducing the crushing circuit from three stages to a single stage. It is also expected to
streamline the permitting process as it eliminates the use of cyanide at the Project.
Comminution:
The below comminution testwork was completed as part of the PFS test program. Results were
mostly consistent with the comminution results from the PEA test program.
• Bond ball work index (BWI) ranged from 14.3 to 23.1 kWh/tonne across 33 samples with
an overall average of 19.0 kWh/tonne (metric)
• Bond rod mill grindability (RWI) ranged from 1 2.6 to 16.0 kWh/tonne across ten samples
with an overall average of 14.4 kWh/tonne (metric)
• Bond abrasion index (Ai) ranged from 0.17 to 0.97 g across ten samples with an overall
average of 0.57 g
Concentrate analysis:
Saleable concentrate grades for both lead (>40% lead and >1,500 g/t silver) and zinc (>50%
zinc) concentrates were readily achieved while the level of penalty elements was low (see table
directly below) confirming excellent saleability of both concentrates.
Element Median Grade1 Penalty Threshold2
Lead Concentrate:
As 0.31% 0.50%
Sb 0.43% 0.50%
Hg 12 ppm 100 ppm
Cl+F 200 ppm 500 ppm
Zinc Concentrate:
As 0.14% 0.30%
Fe 7.00% 8.00%
Cd 0.50% 0.30%
SiO2 3.15% 3.50%
Hg 15 ppm 100 ppm
Cl+F 300 ppm 500 ppm
Mn 0.95% 0.50%
1Median grade was calculated as the median of the concentrates from the 14 locked cycle tests in the PFS test program and the
four locked cycle tests from the PEA test program
2 Penalty thresholds vary between smelters; the thresholds listed above are representative of common thresholds typically applied
on lead and zinc concentrates
PROCESS DESIGN
The process design for the PFS will incorporate staged expansions. The first phase will
incorporate single stage semi -autogenous (“SAG”) milling consisting of a single primary
gyratory crusher, single SAG mill and flotation circuit. This configuration is a common design
with the advantages of being capital efficient and providing expansion flexibility. The planned
throughput rate of this initial phase is expected to be approximately 25,000 tonnes per day
(“tpd”).
The second phase of the mill expansion will include the addition of a ball mill and parallel
flotation circuit. The planned throughput rate of this expanded phase is expected to be
approximately 50,000 tpd.
The proposed process design for the PFS is much simpler and significantly more streamlined
in comparison to the process design assumed in the PEA with the elimination of the heap leach
circuit and the secondary and tertiary crushing circuits. A proposed flowsheet of the updated
process design can be found in Figure D in the appendices.
About Discovery
Discovery’s flagship project is its 100%-owned Cordero project, one of the world’s largest silver
deposits. The PEA completed in November 2021 demonstrates that Cordero has the potential
to be developed into a highly capital efficient mine that offers the combination of margin, size
and scalability. Cordero is located close to infrastructure in a prolific mining belt in Chihuahua
State, Mexico. Continued exploration and project development at Cordero is supported by a
strong balance sheet with cash of approximately C$60 million.
On Behalf of the Board of Directors,
Tony Makuch
Interim Chief Executive Officer and Director
For further information contact:
Forbes Gemmell, CFA
VP Corporate Development
Phone: 416-613-9410
Email: [email protected]
Website: www.discoverysilver.com
Qualified Person
Gernot Wober, P.Geo, VP Exploration, Discovery Silver Corp., is the Company's designated
Qualified Person for this news release within the meaning of National Instrument 43 -101
Standards of Disclosure for Mineral Projects (“NI 43-101”) and has reviewed and validated that
the information contained in this news release is accurate.
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 statements. Forward-looking
statements including, but not limited to Discovery’s future plans and objectives regarding the Cordero Project and the prospect of
further discoveries there, which constitute forward looking information that involve various risks and uncertainties . 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. Discovery does not assume
any obligation to update any forward-looking statements except as required under applicable laws.
APPENDICES
TABLE 1 – PFS Locked Cycle Test Results
Test Type Rock Type /
Sample Location
Head Grade
Lead Circuit Zinc Circuit
Recovery to
Concentrate
Concentrate
Grade
Recovery to
Concentrate
Concentrate
Grade
Ag Pb Zn AgEq Ag Pb Ag Pb Ag Zn Ag Zn
(g/t) (%) (%) (g/t) (%) (%) (g/t) (%) (%) (%) (g/t) (%)
High-Grade
Breccia 252 3.8 2.6 462 93 96 4,634 73 4 93 219 52
Volcanic 71 1.9 5.1 319 91 97 2,518 72 6 92 55 57
Volcanic 46 0.9 2.1 151 86 93 3,270 69 8 96 100 56
Sedimentary 41 0.8 1.6 128 81 89 2,395 53 13 96 182 53
Rock Type
Blend
Starter Pit 37 0.6 0.6 76 85 92 3,516 57 7 89 287 53
NE Extension 29 0.5 0.7 70 81 90 3,085 61 10 84 249 51
South Corridor 33 0.4 0.8 76 65 85 2,868 44 18 85 446 53
Run of Mine 33 0.5 0.8 76 75 89 3,643 62 12 81 385 59
Low-Grade Volcanic 10 0.1 0.2 21 26 64 712 19 17 62 550 34
Breccia 30 0.3 0.1 44 69 87 4,277 52 7 64 1,042 46
10% Oxide /
90% Sulphide
Blend
Starter Pit 40 0.5 0.5 76 78 84 3,694 57 7 89 321 52
NE Extension 29 0.5 0.6 66 78 86 3,250 61 9 87 255 54
South Corridor 33 0.4 0.7 71 65 80 3,369 49 16 88 434 52
Run of Mine 35 0.5 0.7 74 73 84 3,506 54 11 88 335 51
FIGURE A – Global Ag Recovery vs Ag Head Grade
FIGURE B – Pb Recovery vs Pb Head Grade
75
80
85
90
95
100
20 30 40 50 60 70 80
Ag Recovery to Pb+Zn con (%)
Ag Head Grade (g/t)
PFS Sulphide Test
PFS Oxide/Sulphide
Blend Test
PEA Sulphide Test
60
65
70
75
80
85
90
95
100
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
Pb Recovery to Pb con (%)
Pb Head Grade (%)
PFS Sulphide Test
PFS Oxide/Sulphide
Blend Test
PEA Sulphide Test
FIGURE C – Zn Recovery vs Zn Head Grade
60
65
70
75
80
85
90
95
100
0.00 0.50 1.00 1.50 2.00 2.50 3.00
Zn Recovery to Zn con (%)
Zn Head Grade (%)
PFS Sulphide Test
PFS Oxide/Sulphide
Blend Test
PEA Sulphide Test