The Klaza Project 2017 Technical Report presents an updated mineral resource estimate and a modified metallurgical treatment scheme for the Klaza property in Yukon, Canada.
Report context
The report describes updated diamond drilling, metallurgical testing, and mineral resources for the Klaza Property, Yukon, Canada. It was prepared for Rockhaven Resources Ltd. and includes an update to the previous preliminary economic assessment (PEA) technical report from February 2016. The updated report incorporates 2016 and 2017 drilling results and additional metallurgical studies, though it notes that the PEA studies have not yet been updated to consider the new mineral resource model or the modified metallurgical treatment scheme.
Processing route
Proposed flowsheet overview
The currently perceived flowsheet remains largely consistent with the 2016 PEA, except for the potential option of directly selling sulphide concentrate. The proposed process includes crushing, gravity pre-concentration, grinding, sequential flotation, and alternative treatment routes depending on the material source and concentrate destination.
Crushing and gravity pre-concentration
Since the 2016 PEA, gravity pre-concentration has been added to reduce the tonnage feeding the grinding and flotation circuits by approximately 50%. Run-of-mine material from Western, Central, and Eastern BRX, as well as Central Klaza, would be crushed to 9.5 mm. Fines would be screened out at 1.4 mm. Gravity pre-concentration, potentially using jigging or dense media separation, would be applied to the coarse fraction. This would generate a high-grade concentrate to be blended with the fines and fed to the grinding circuit. Pre-concentration tails, a desulphurized crusher product sized at 1.4–9.5 mm and comprising roughly 50% of run-of-mine tonnage, would be stored.
Grinding and flotation
After primary grinding, sequential rougher and cleaner flotation would produce a gold-rich lead concentrate and a zinc product. The lead concentrate would undergo intensive leaching to extract most of the gold before shipment to market, with the extracted gold upgraded to doré. The zinc product, being poorer in gold, would be shipped directly without further processing.
The zinc circuit tails would be subjected to flotation of gold-bearing sulphides, comprising a blend of pyrite and arsenopyrite. The precise mix would depend on whether the concentrate was to be processed on-site using pressure hydrometallurgy or sold to a third party.
Eastern BRX processing
Material from Eastern BRX would be treated separately using a process that integrates flotation with concentrate direct cyanidation. With the exception of a single regrind mill, this process would use equipment already in place for the rest of the project. No pressure hydrometallurgy would be required for Eastern BRX material, and only doré would be produced for sale.
Tailings management
Final flotation tails, comprising about 40% of the original mill feed, would be stored in a tailings impoundment. Two tailings streams requiring disposal would be produced: hydromet residue and flotation tailings. These would be managed separately based on geochemical properties.
The Hydromet Residue Storage Facility would be positioned adjacent to the plant and hydromet residues, expected to be relatively stable but high in arsenic, would be contained within a lined engineered containment.
Flotation tailings would be deposited by gravity around the facility perimeter through sequential discharge using subaerial and subaqueous deposition techniques. The facility would be situated downgradient from the plant. Embankment construction would use the downstream method, staged in two-year increments with three elevation stages, ultimately reaching 1,211 m in Year 4.
The Stage 3 embankment would be roughly 25 m high and 1 km long, with total fill volume estimated at 952,000 m³. Waste rock would be used for most construction. Open pits Klaza 1 and Klaza 2 would be used for tailings storage starting in Year 7, with the pits filled to the rim and capped with waste rock and overburden at closure.
Water management
Key facilities include open pits, underground mine dewatering, the mill, tailings storage facility, diversion structures, and fresh water supply. The strategy would maximize internal water use, with no surface water discharge from tailings facilities during operations. Under average conditions the site would operate in water deficit, requiring additional makeup water from the Klaza River at 685 m³/day.
Average annual runoff into the hydromet and flotation tailings facilities would be approximately 67,000 m³, pit runoff and dewatering would contribute 60,000 m³, and mine dewatering would provide approximately 50,000 m³ annually. Water retained in tailings voids, about 250,000 m³ annually, would require replacement from river pumping.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Crush size | 9.5 mm | Proposed design |
| Fines screen size | 1.4 mm | Proposed design |
| Tonnage reduction from gravity pre-concentration | ~50% | Proposed design |
| Pre-concentration tails as % of ROM | ~50% | Proposed design |
| Final flotation tails as % of mill feed | ~40% | Proposed design |
| Embankment slopes | 2.5H:1V upstream and downstream | Conceptual design |
| Stage 1 embankment elevation | 1,203 m | Design |
| Stage 2 embankment elevation | 1,207 m | Design |
| Stage 3 embankment elevation | 1,211 m | Design |
| Stage 3 embankment height | ~25 m | Design |
| Stage 3 embankment length | 1 km | Design |
| Stage 3 fill volume | 952,000 m³ | Design estimate |
| Lined facility area | 65,000 m² | Design |
| Klaza 1 pit storage capacity | 670,000 m³ (871,000 t) | Historical evaluation |
| Klaza 2 pit storage capacity | 2,100,000 m³ (2,730,000 t) | Historical evaluation |
| Average annual runoff to tailings facilities | ~67,000 m³ | Water balance modelling |
| Average annual pit runoff/dewatering | ~60,000 m³ | Water balance modelling |
| Annual mine dewatering contribution | ~50,000 m³ | Water balance modelling |
| Annual water retained in tailings voids | ~250,000 m³ | Water balance modelling |
| River makeup pumping rate | 685 m³/d | Water balance modelling |
| Potable water demand | ~7,000 m³ annually | Conceptual design |
| Road watering demand (summer) | ~14,000 m³ annually | Conceptual design |
| Underground water consumption | ~38,000 m³ annually | Conceptual design |
Project website: https://www.rockhavenresources.com/projects/klaza-project
Technical qualifications
The 2017 report discloses results of an updated mineral resource estimate incorporating 2016 and 2017 drilling results, along with additional metallurgical studies. It serves as an update to mineral resources and metallurgical results previously reported in the PEA technical report prepared in February 2016. The 2016 PEA results described in this report are based on the earlier mineral resource model, and the studies related to the PEA have not yet been updated to consider the new mineral resource model or the modified metallurgical treatment scheme.
The tailings management section was taken directly from the NI 43-101 technical report dated 26 February 2016 and remains unchanged, included for completeness and continuity.
Source: *Technical Report Describing Updated Diamond Drilling, Metallurgical Testing and Mineral Resources on the Klaza Property, Yukon, Canada*, Rockhaven Resources Ltd., 718018, amcconsultants.com, Section 17.
