Rockhaven Reports Excellent Pre-Concentration Results for the Klaza Deposit, Yukon Bulk sample test work ~doubles potential grade by rejecting >50% of the initial feed
510 – 1100 Melville Street
Vancouver, BC V6E 4A6
604-687-2522
www.rockhavenresources.com
1 See Rockhaven news release dated June 21, 2018 for more information on the mineral resource estimate for the Klaza deposit.
Rockhaven Reports Excellent Pre-Concentration Results for the Klaza
Deposit, Yukon
Bulk sample test work ~doubles potential grade by rejecting >50% of the initial feed
September 12, 2023 - Rockhaven Resources Ltd. (TSX-V:RK) (“Rockhaven”) is pleased to
announce encouraging results from comprehensive pre-concentration (sorting) test work on bulk
samples of material selected from within the mineral resources at its 100% owned Klaza Au-Ag-
Pb-Zn d eposit, Yukon 1. The test work results demonstrate the potential effectiveness of pre-
concentration of Klaza mineralisation at a coarse crush size , by doubling the grade of material
entering the mill and reducing the mill feed tonnage by over 50%, with only minor losses in metal.
Positive impacts on potential future operations that may result from the use of pre -concentration
include a material reduction in the amount of flotation tails, a significantly smaller grinding and
flotation circuit and, potentially, lower overall capital and operating costs for such an operation .
Once trade-off studies are completed, the revised flow sheet and cost estimates that result from the
use of pre-concentration may also be employed to help in the determination of cut-off grades for
the pending updated mineral resource estimation, as well as for the economics of the upcoming
pre-feasibility study.
Highlights
• Crushing to a top size of 63mm , pre-concentration has been conducted on bulk
samples with grades representative of the Klaza and BRX mineral resources.
• The pre-concentration:
o rejected greater than half of the initial feed material , while maintaining
average recoveries of 93% for Au, 94% for Ag, 96% for Pb and 92% for Zn.
o led to an approximate doubling of the grade of the potential feed to a mill for
all metals of economic interest (Au, Ag, Pb and Zn).
• It is expected that the adoption of pre-concentration could lead to significantly
smaller grinding and flotation circuits, with lower overall capital and operating
costs.
• Positive environmental impacts could be expected to result from the adoption of
pre-concentration due to the significant reduction in the amount of flotation tails.
• Incorporating pre-concentration into a process circuit could potentially lower the
cut-off grades for future mineral resource estimates.
• Testing of a composite of material below the assumed cut-off grade for the mineral
resource yielded a significant increase in grade by eliminating 65% of the feed
material, while still recovering 80% of the gold and 93% of the silver. This could
result in material previously assumed to be below future cut-off grades having
potential value and being incorporated into the planned pre-feasibility study.
Statement from Rockhaven’s President and CEO, Matt Turner:
DRAFT
2
“With high recoveries, low mass pulls and a substantial increase in the grade of the material going
to a future mill, the pre-concentration results demonstrate a potentially positive shift in several
economic inputs, which could significantly reduce capital and operating costs of a potential future
mining operation at Klaza . Beyond cost-efficiencies related to milling fewer tonnes for similar
contained metals, other advantages of using this technology may include a significant reduction
in the amount of flotation tails, less haulage of material from underground operations, and lower
mining cut-off grades by upgrading material that was previously expected to fall below future
economic cut-off grades. Trade-off studies will begin shortly to optimize the degree to which pre-
concentration could be adopted, which will help to set the stage for the upcoming mineral resource
estimate and pre-feasibility study.
Pre-concentration Technology
The pre-concentration (commonly referred to as “ore sorting”) production-scale test work was
done at the Saskatchewan Research Council Geoanalytical Laboratories (SRC) facility in
Saskatoon and utilized TOMRA X-Ray Transmission (XRT) sensor based sorting technology to
concentrate high-density sulphide minerals which are associated with gold-silver-lead-zinc
mineralization at Klaza. Rocks are individually scanned while they move along a conveyor belt,
and compressed air jets selectively eject mineralized material at specified densities. The low
density ‘waste’ material is further subjected to additional ‘cascade’ tests to determine the mass
pulls at subsequent lower density settings . The ejected material (“accepts”) from each density
setting is weighed, crushed and assayed, as well as the waste material from the final run. Once the
results are compiled and interpreted, the optimal density settings are determined.
Pre-concentration Test Work and Results
Phase I began with scanning 300 mineralized and unmineralized rock pieces using TOMRA XRT
detection technology from split drill core samples collected at Klaza. Detection information from
the XRT indicated that there was good contrast between particles which could lead to a high
recovery and low yield on a bulk scale. About a third of the scanned pieces were individually
assayed, and these results further confirmed the ability of the detection technology to sort
mineralised material from waste.
In the second phase, some 480 kg of coarse drill core material from the Klaza and BRX zones ,
with mean grades designed to reasonably represent potential mill feed grades from each deposit,
was gathered from site. These were split into two “life-of-mine” feed grade composites (from
Klaza and BRX) and one “Low Grade” composite. The Low-Grade composite included a mix of
lower grade material from the BRX and Klaza Zones and assayed below the cut-off grades used
in the current Klaza Deposit mineral resource estimate (see news release dated June 21, 2018) .
The grades of all three composites are shown below:
Table 1: Feed Composite Assays:
Composite assays
Au, g/t Ag, g/t Pb, % Zn, %
BRX 2.31 88 0.87 1.04
Klaza 2.45 63 0.67 0.85
Low Grade 0.35 29 0.17 0.21
DRAFT
3
Each of the three composites was crushed to less than 63mm in size. The crusher product was
screened at 9.5mm . The coarse r fraction comprising the bulk of the tonnage was subjected to
sorting. A subsample of the -9.5mm material was screened again at 1.2mm and the coarser fraction
subjected to gravity separation testwork; the -1.2mm fines were kept aside. In practice the finest
material would be delivered directly to the mill.
For each composite, a production scale TOMRA COM 1200 Tertiary XRT sorting machine was
used to complete the pre -concentration of the coars e fraction, while heavy liquids were used to
simulate gravity concentration of the mid -size fraction. For each composite, the resulting pre-
concentrate comprised the sorting “accepts”, the heavy liquid concentrate and the sub -1.2mm
fines.
Pre-concentration of the BRX and Klaza composite samples recovered, on average, 93% of the
gold, 94% of the silver, 96% of the lead and 92% of the zinc, to a product comprising 47% of the
original sample mass. The results are tabulated below.
Table 2: Pre-concentrate assays and Recovery of Metals to Pre-concentrate
Pre-concentrate Assays Recovery
Mass % Au Ag Pb Zn Au Ag Pb Zn
g/t g/t % % % % % %
BRX 48 4.29 169 1.71 1.99 92 94 97 92
Klaza 46 4.94 130 1.40 1.70 93 94 95 91
Low Grade 35 0.79 77 0.43 0.49 80 93 89 85
The objective of the test work on the low-grade composite was to establish if sufficient upgrading
was achieved to convert below cut -off grade material to material that would potentially be
economic for further processing. This potential will be assessed through both the updated mineral
resource estimation and ongoing economic studies, but the more than doubling of all metal grades
at high metal recovery, with just a 35% mass pull, is encouraging.
Qualified Persons
Technical information related to the metallurgical test program were provided and approved by
Chris Martin, C.Eng. an independent consultant and qualified person for the purpose of National
Instrument 43-101. All other technical information related to this news release has been approved
by Matthew R. Dumala, P.Eng., a geological engineer with Archer, Cathro & Associates (1981)
Limited and qualified person for the purpose of National Instrument 43-101.
About Rockhaven
Rockhaven Resources Ltd. is focused on advancing its 100%-owned, camp-scale Klaza Property,
which hosts the Klaza Deposit and numerous lightly explored exploration targets. Rockhaven has
completed a mineral resource estimate and a preliminary economic assessment on the Klaza
deposit (see Klaza Property Technical Report with an effective date of July 10, 2020 and titled,
“Technical Report and Preliminary Economic Assessment Update for the Klaza Property, Yukon,
Canada.” which can be viewed at www.sedar.com under the Rockhaven profile or on the
Rockhaven website at www.rockhavenresources.com). Rockhaven anticipates the release of a Pre-
feasibility study for Klaza in the first half of 2024.
DRAFT
4
Matthew Turner
President, CEO and Director
Rockhaven Resources Ltd.
T:604-687-2522
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.
Forward Looking Statements
Information contained in this news release contains forward-looking statements. These statements
reflect management ’s current estimates, beliefs, intentions and expectations; they are not
guarantees of future performance. Forward-looking statements are statements that are not
historical facts and are generally, but not always, identified by the words “potential”, “objective”,
“encouraging”, “expect”, “future’, “positive”, “high”, “comprehensive”, “significant”, “positive”
“planned”, “optimize”, “interpreted” , “anticipates”, variations of su ch words and similar
expressions, or that events or conditions “could”, “may”, “would” or “will” occur. Rockhaven
cautions that all forward-looking statements are inherently uncertain, and that actual performance
may be affected by a number of material factors, many of which are beyond the control of
Rockhaven. Such factors include, among other things: risks and uncertainties relating to
exploration and development and the results there of, including the results of completed drill
programs; the impact on mineral resource estimates and existing economic studies of such
completed and planned work; the potential for new discoveries ; and the results of planned
metallurgical and geotechnical programs including the potential benefits of pre -concentration on
higher and lower grade material; the advancement of exploration targets through future
exploration; the outcome of the planned mineral resource estimate update and the prefeasibility
study, including the impacts of pre-concentration and whether or not such is incorporated into the
estimate and the study; the ability of Rockhaven to obtain additional financing; the need to comply
with environmental and governmental regulations ; fluctuations in the prices of commodities ;
operating hazards and risks ; competition; and other risks and uncertainties, including those
described in Rockhaven’s financial statements available under the Rockhaven profile at
www.sedar.com. Accordingly, actual and future events, conditions and results may differ
materially from the estimates, beliefs, intentions and expectations expressed or implied in the
forward-looking information. Except as required under applicable securities legislation,
Rockhaven undertakes no obligation to publicly update or revise forward-looking information.