This Preliminary Economic Assessment describes a low-risk, proven flowsheet for diamond recovery from the CH-6 and CH-7 kimberlite bodies, designed for the Arctic operating environment.
The Chidliak Project Preliminary Economic Assessment (PEA) details a process design for diamond extraction largely based on current Northern Canadian kimberlite processing techniques, as limited metallurgical data for the CH-6 and CH-7 kimberlite material had been developed at the time of the study. The flowsheet’s primary purpose is to maximize diamond liberation and economic recovery while minimizing the building footprint, energy requirements, and operational complexity in an Arctic setting. The design criteria specify a plant throughput of 2,000 tonnes per day, corresponding to 730,000 tonnes per year, supporting a potential mine life of up to 13 years based on an indicated mineable resource of 9.5 million tonnes.
The process design is built on the operational experience of similar Canadian diamond plants, including Ekati, Diavik, Snap Lake, and Jericho. This approach is intended to reduce training and operational ramp-up times, improve start-up and production stability, and allow for the use of existing vendor support. Standardized equipment sizes are used to reduce on-site spares holdings. Given the climatic constraints, minimizing material impact breakage is a key design criterion; therefore, primary crusher gap settings of greater than 30 mm are specified, and drop heights and transport velocities are minimized to protect diamonds. The process is designed to treat a nominal upper size of 30 mm and a lower size of 1 mm. The plant’s process water is not heated, drawing on existing Northern operations' experience that shows no advantage in doing so.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Plant Throughput | 2,000 | t/d | Design criteria |
| Plant Throughput | 730,000 | t/a | Design criteria |
| Crushing Section Utilization | 65 | % | Design criteria |
| Crushing Section Throughput | 130 | t/h | Design criteria |
| Kimberlite UCS : CH-6 | 60-140 | MPa | Peregrine |
| Kimberlite UCS : CH-7 | 40-145 | MPa | Peregrine |
| Process Plant Utilization | 85 | % | Design criteria |
| Plant Throughput | 100 | t/h | Design criteria |
| Processing Power Consumption | 14 | kWh/t | Design criteria |
| DMS Feed Rate | 150 | t/h | Design criteria |
| DMS Feed Bin Stockpile Capacity | 4,000 | t | Approximately 2-days plant feed capacity |
| Plant Make-up Water Requirement | 50 to 80 | m³/h | 15% of total process water |
Overview
The PEA for the Chidliak Project establishes a preliminary, simplified diamond processing flowsheet. Because of the lack of ore dressing studies and limited metallurgical data on the CH-6 and CH-7 kimberlite material, the design relies on well-established Canadian kimberlite processing techniques suitable for an Arctic environment. The process design aims to maximize diamond liberation and value recovery while being robust and energy-efficient, minimizing both the building footprint and the associated heating requirements. The plant is designed to operate at a nominal throughput of 2,000 t/d, processing a potential mineable resource of 9.5 Mt over a LOM of up to 13 years.
Key Process Stages
The process plant begins with a crushing section enclosed to protect equipment from the Arctic climate, with heating controls maintaining an operating temperature of approximately 0°C during the sub-zero winter months. Front-end loaders feed the run-of-mine (ROM) material from stockpiles into the crushing plant, allowing for pre-sorting of large oversize and waste rock, as well as feed blending. The crushing plant's major equipment includes a primary jaw crusher and secondary cone crusher. The crusher product is delivered to a crushed ore stockpile, which provides approximately 4,000 t of covered storage, equivalent to two days of plant feed capacity.
From the stockpile, material is fed by a front-end loader via a static grizzly and feed hopper into the process plant. Ferrous tramp metal is removed at the discharge of the plant feed conveyor. Initial sample processing data indicates that the expected amount of clay in the plant feed is very low, even for weathered kimberlite. The plant feed is sized and washed on horizontal deck and banana type vibrating screens. The -1 mm fines report to the fines pumpbox, while the -75 + 30 mm size fraction is conveyed to an HPGR feed bin. A drum scrubber may be used depending on additional metallurgical data, but its location in the flowsheet is pending further study. The crushed stockpile material is fed to the process plant via a belt weigh feeder.
The -75 + 30 mm material from the feed preparation stage is fed to the HPGR, which is used ahead of the Dense Media Separation (DMS) plant to maximize fines generation and reduce downstream treatment capacity requirements. The HPGR product is then fed to the DMS plant. A single size fraction DMS plant has been proposed to minimize the overall plant footprint and reduce DMS plant capacity redundancy. The proposed DMS plant, designed for 150 t/h, will use three 420 mm diameter pump-fed cyclones. Material is mixed with ferrosilicon (FeSi) medium in a feed mixing box to the correct density. The DMS concentrate discharges into a secured Recovery Plant feed surge bin, monitored by CCTV.
DMS cyclone float material is sized on a double deck drain and rinse screen, with the -30 + 8 mm oversize fraction returning to the HPGR feed bin. The DMS concentrate reports to the recovery plant, which consists of a simplified wet X-ray and grease table plant. The recovery plant flowsheet requires further development pending additional metallurgical and equipment vendor data. The plant's process water is not heated. Thickener overflow gravitates to the process water tank for reuse, and a reclaim water pump located in the fine tailings impoundment returns raw water to the plant process water tank.
Additional Interesting Data and Summary
The process plant design includes several features to reduce operational costs and complexity. High process energy efficiency is achieved by keeping material elevations to a minimum, reducing circulating loads, and using high-efficiency comminution like the HPGR and wet X-ray treatment to reduce drying costs. The use of pump-fed cyclones for the DMS plant reduces the material conveying and elevation required for gravity-fed cyclones. Diamond valuation cycles are expected to be conducted on a four to six-week basis. The overall flowsheet is designed to be a balance of proven technology and design efficiency, with a clear focus on the specific constraints of the Arctic environment and the geological characteristics of the kimberlite.
Key Processes
- Crushing: Conventional primary jaw and secondary cone crushing.
- Comminution: HPGR to maximize fines generation and reduce DMS feed.
- Screening: Horizontal deck and banana type vibrating screens for sizing and washing.
- Dense Media Separation: Single size fraction DMS using 420 mm pump-fed cyclones with FeSi medium.
- Recovery: Simplified wet X-ray and grease table plant.
- Tailings: Process water is recovered from a thickener and a fine tailings impoundment for reuse.
Source: Chidliak Project , PEA Technical Report, Unknown.
Project website: Chidliak Project, PEA Technical Report
