Bonterra Achieves up to 99.4% Gold Recoveries from Preliminary Metallurgical Studies, Including up to 76.1% from the Gravity Circuit
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Bonterra Achieves up to 99.4% Gold Recoveries from Preliminary
Metallurgical Studies, Including up to 76.1% from the Gravity Circuit
Vancouver, BC – April 17, 2018: Bonterra Resources Inc. (TSX-V: BTR, OTCQX: BONXF,
FSE: 9BR1) (the “Company” or “Bonterra”) is pleased to announce that it has received highly
positive results for its preliminary metallurgical testwork, wh ich forms part of its ongoing
Resource Development Program at its 100% controlled Gladiator G old Deposit in Quebec,
Canada. Results to date show total gold recoveries of up to 99.4%, including 76.1% from the
Gravity circuit.
“The outstanding metallurgical resu lts, when compared to the overall average lower recoveries
within our industry peer group, ar e a significant milestone for th e Gladiator Gold Deposit. The
exceptional gravity recovery rates of up to 76.1% , combined with a simple flotation circuit, may
reduce capital requirements related to a future potential milling operation,” commented Nav
Dhaliwal, CEO of Bonterra. “Potentially not requiring a cyanide leaching circuit minimizes the
environmental footprint of any future mining operation and could also improve potential future
process economics of the project.”
Highlights and Observations:
The combination of gravity and gravity-cyanide tests resulted in significant gold recoveries
of 99.0% to 99.4%.
The combination of gravity and gravity-tail flotation tests res ulted in significant gold
recoveries of 96.8% to 97.3%.
Excellent gravity concentrate recoveries, ranging from 68.3% to 76.1%, are well above
the average of Bonterra’s industry peers and confirm the presence of a significant
amount of free gold in the mineralized system.
Average >70% of the gold reported to the Gravity circuit at all grinding test sizes,
indicating substantial potential capital and operating savings in the grinding circuits.
A cyanide leaching circuit may not be required, noting the high recovery of the gold
from the gravity and gravity-tail flotation tests.
Head assay results from the metallurgical testing ranged from 8.0 g/t Au to 10.0 g/t Au and
showed excellent grade reconciliation with initial drill hole assays.
“As expected, preliminary metallurgical test re sults confirmed excellent gold recoveries. On
average, greater than 70% of the gold reports to th e gravity circuit at all grinding sizes, which
potentially contributes to substantial capital re ductions in the grinding circuits, potential lower
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reagent consumption, and highlights an opportunity for significant savings in the future processing
parameters at Gladiator,” commented Peter A. Ball, VP Operations. “The simple metallurgy,
consisting of potentially only a crushing and grinding circuit to achieve 76.1% recovery, provides
a low CapEx/OpEx process to pour gold bullion on site. Adding a flotation circuit could yield up
to 97.3% recovery and deliver a very high grade gold concentr ate, making material very
compatible and easily transported to a local or a centralized standard milling facility.”
Metallurgical Program Review
ALS Metallurgy (“ ALS”) of Kamloops, British Columbia , was contracted to complete Gr avity
Concentration, Flotation and Cyanide leach testing for the Glad iator Gold Deposit. The studies
included grind optimization, grav ity separation, flotation, and cyanide leach testing, and were
intended to provide an initial l ook at the characteristics of m ineralization to help guide future
optimization test work and processing flow sheet specifications.
Overall, the metallurgical testing and microscopic analysis ind icate that the mineralization is
relatively simple with no deleterious elements, and pre-concentration could potentially be achieved
by a low capital intensive processing sequence, which will like ly include crush ing, grinding,
gravity concentration and flotation. The process is a relatively benign one, and also offers potential
environmental permitting advantages, as well as significant savings in transportation costs. These
results are part of an ongoing c omprehensive metallurgical program designed to define
the processing parameters, establish grade-recovery relationships and optimize gold recovery for
a potential future Gladiator milling facility.
ALS completed testing on approximately 35 kg of composite sample from the Main Zone with an
average head grade of 9.0 g/t Au from two wide diameter holes M T-18-01 and MT-18-02. The
composite sample was selected to be representative of the depos it mineralization based on
mineralogy, grade and location. Head assay results from the metallurgical testing ranged from 8.0
g/t Au to 10.0 g/t Au and showed excellent grade reconciliation with initial drill hole assays.
Four kg of the sample, at three different grind sizings, were submitted for gravity separation using
a Knelson concentrator. Gold recovery by the Knelson gravity se paration was followed by hand
panning to produce a final gravity concentrate mass that is more representative of plant operation.
The pan concentrate, pan tailings, and Knelson concentrator tai ls were assayed for gold and
determined that gold in the samples were highly amenable to gravity recovery.
Results of the Gravity concentration gold recovery tests are summarized below:
Test Size
Feed Grade
(g/t Au)
Knelson Tails
(%)
Pan Tails
(%)
Pan Concentrate
(%)
Pan Concentrate
(g/t Au)
1 169 m K80 9.19 20.0 11.7 68.3 3,627
2 136 m K80 9.86 13.6 11.9 74.5 4,437
3 83 m K80 8.70 13.0 10.8 76.1 6,461
Results of the Flotation concentration gold recovery tests are summarized below:
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Test Size
Feed
Grade
(g/t Au)
Gravity Recovery
Distribution %
Rougher Recovery
Distribution %
Total Recovery -
Distribution %
Au S Au S Au S
4 169 m K80 10.0 73.0 18.8 23.5 72.0 96.5 90.8
5 136 m K80 8.00 70.9 17.1 26.0 73.9 96.8 91.0
6 83 m K80 8.28 73.8 13.0 23.5 78.5 97.3 88.2
Results of the Cyanide concentration gold recovery tests are summarized below:
Test Size
Leach Feed
(Gravity Tails)
Au Recovery
Gravity
(%)
Leach
Extraction
(%)
Au Recovery
Gravity Tails
(%)
Au Recovery
Total
(%)
7 169 m K80 Test 1 68.3 30.7 30.7 99.0
8 136 m K80 Test 2 74.5 24.9 24.9 99.4
9 83 m K80 Test 3 76.1 23.1 23.1 99.2
A kinetic rougher test was included in each flotation feed sizing. This test determined that gold in
the samples is highly amenable to recovery using a standard froth flotation circuit.
Gravity plus cyanidation leach tests were completed, and it was determined that gold in the samples
responded excellent to conventional leaching. Three of the tests were conducted on the samples at
each grind sizing, and three of the tests were conducted on the rougher flotation tailings.
Bonterra is currently completing a Resource Development Program in 2018 at the Gladiator Gold
Deposit, including approximately 70,000 m of drilling, metallur gical studies, and a Mineral
Resource update.
Bonterra Resources Quick Facts:
Well financed with approximately $60 million raised in past 14 months.
Strong Shareholder Base including: Eric Sprott, Van Eck, Kirkland Lake Gold
Gladiator Gold Deposit:
o Deposit extension and resource expansion underway with 60,000 m completed in 2017
and 70,000 m planned for 2018.
o Advancing to the completion of an updated NI 43-101 Mineral Res ource Estimate in
the second half of 2018.
o Drilled dimensions of the Gladiator Gold Deposit are currently outlined to a depth of
1,000 m below surface, and a strike length of 1,200 m.
o Gladiator remains open in all directions, where at least six di stinct sub-parallel zones
or mineralized horizons have been identified.
o Drilling is currently focused on the continued expansion of Gla diator Gold Deposit
and exploration targets within the 10,541-hectare Urban-Barry property.
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Larder Lake Gold Property:
o 100% controlled 2,221-hectare in the Cadillac-Larder Break camp in Ontario (refer to
March 17, 2016 news release highlighting historical gold resource).
o Excellent access to three high grade gold deposits between Kirk land Lake and
Virginiatown.
Robert Gagnon, P.Geo., has approved the information contained i n this release. Mr. Gagnon is a
director of Bonterra and is a Qualified Person as defined by NI 43-101.
ON BEHALF OF THE BOARD OF DIRECTORS,
Nav Dhaliwal, President & CEO
Bonterra Resources Inc.
For further information on Bonterra, contact Investor Relations
Telephone: 1 844 233 2034
Email: [email protected]
Website: www.bonterraresources.com
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forecasts and projections. This forward-looking information includes, among other things, statements with respect to
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factors include, but are not limited to: uncertainties related exploration and development; the ability to raise sufficient
capital to fund exploration and development; changes in economic conditions or financial markets; increases in input
costs; litigation, legislative, environmental and other judicial, regulat ory, political and comp etitive developments;
technological or operational difficulties or inability to obtain permits encountered in connection with exploration
activities; and labour relations matters. This list is not exhau stive of the factors that may affect our forward-looking
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