Mr. Matthew Turner reports

ROCKHAVEN REPORTS EXCELLENT PRE-CONCENTRATION RESULTS FOR THE KLAZA DEPOSIT, YUKON

Rockhaven Resources Ltd. has released encouraging results from comprehensive preconcentration (sorting) testwork on bulk samples of material selected from within the mineral resources at its 100-per-cent-owned Klaza gold-silver-lead-zinc deposit, Yukon. The testwork results demonstrate the potential effectiveness of preconcentration of Klaza mineralization at a coarse crush size, by doubling the grade of material entering the mill and reducing the mill feed tonnage by over 50 per cent, with only minor losses in metal. Positive impacts on potential future operations that may result from the use of preconcentration 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 preconcentration 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 coming prefeasibility study.

Highlights:

• Crushing to a top size of 63 millimetres, preconcentration has been conducted on bulk samples with grades representative of the Klaza and BRX mineral resources.
• The preconcentration:
  • Rejected greater than half of the initial feed material, while maintaining average recoveries of 93 per cent for gold, 94 per cent for silver, 96 per cent for lead and 92 per cent for zinc;
  • 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 preconcentration 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 preconcentration due to the significant reduction in the amount of flotation tails.
• Incorporating preconcentration 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 per cent of the feed material, while still recovering 80 per cent of the gold and 93 per cent 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 prefeasibility study.

Rockhaven's president and chief executive officer, Matt Turner, stated: "With high recoveries, low mass pulls and a substantial increase in the grade of the material going to a future mill, the preconcentration 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 preconcentration could be adopted, which will help to set the stage for the coming mineral resource estimate and prefeasibility study.

Preconcentration technology

The preconcentration (commonly referred to as ore sorting) production-scale testwork 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.

Preconcentration testwork and results

Phase 1 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 was individually assayed, and these results further confirmed the ability of the detection technology to sort mineralized material from waste.

In the second phase, about 480 kilograms 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 in an attached table.

Each of the three composites was crushed to fewer than 63 millimetres in size. The crusher product was screened at 9.5 mm. The coarser fraction comprising the bulk of the tonnage was subjected to sorting. A subsample of the minus-9.5-millimetre material was screened again at 1.2 mm, and the coarser fraction was subjected to gravity separation testwork. The minus-1.2-millimetre 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 preconcentration of the coarse fraction, while heavy liquids were used to simulate gravity concentration of the mid-size fraction. For each composite, the resulting preconcentrate comprised the sorting accepts, the heavy liquid concentrate and the sub-1.2-millimetre fines.

Preconcentration of the BRX and Klaza composite samples recovered, on average, 93 per cent of the gold, 94 per cent of the silver, 96 per cent of the lead and 92 per cent of the zinc to a product comprising 47 per cent of the original sample mass. The results are tabulated.

The objective of the testwork 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 continuing economic studies, but the more than doubling of all metal grades at high metal recovery, with just a 35-per-cent mass pull, is encouraging.

Qualified persons

Technical information related to the metallurgical test program was provided and approved by Chris Martin, CEng, 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, PEng, a geological engineer with Archer, Cathro & Associates (1981) Ltd. and a qualified person for the purpose of National Instrument 43-101.

About Rockhaven Resources Ltd.

Rockhaven is focused on advancing its 100-per-cent-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 SEDAR+ under the Rockhaven profile or on the Rockhaven website. Rockhaven anticipates the release of a prefeasibility study for Klaza in the first half of 2024.

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