Davidson Project: Underground Molybdenum Processing at 10,000 tpd

Source: Unnamed_Company_75 (2026)
Website: https://moonrivermoly.com/projects/davidson-project/

Critical Data

Overview

The Davidson Project, operated by Moon River Moly Ltd., proposes a groundbreaking 10,000 tonnes per day (tpd) processing facility built entirely underground, located above the main mineralized zones at the 1,420 Level elevation near Smithers, British Columbia. This innovative approach, detailed in a NI 43-101 technical report with an effective date of December 23, 2025, significantly reduces the surface footprint and visual impact while eliminating the need to transport ore to an external plant. The underground mill also provides a ready source of backfill material for mined-out stopes by utilizing tailings as cemented paste backfill. The process flowsheet integrates three-stage crushing, rod mill/ball mill grinding, and a comprehensive flotation circuit for primary molybdenum recovery, with byproduct recovery of copper and tungsten. The molybdenum flotation circuit includes rougher cells, an IsaMill for regrinding, and column cells for cleaning. Copper is recovered via a dedicated flotation stage, while tungsten is concentrated using gravity methods—centrifugal concentrators and shaking tables. The facility is designed to operate 24 hours per day, 7 days a week, with an estimated annual operating expense of $40.56 million (CAD 2025) or $11.11 per tonne. This underground processing strategy represents a significant advancement in sustainable mining, reducing surface disturbance and optimizing material handling.

Key Process Stages

• Stage 1: Three-Stage Crushing – Primary crushing uses two jaw crushers each treating 300 tph, discharging onto 0.76 m wide conveyors feeding a 13,000 tonne coarse ore bin (17 m × 17 m × 30 m). Secondary crushing employs a single 670 kW cone crusher in open circuit, with undersize passing a 3 m × 6.1 m double-deck vibrating screen (urethane media) into a 10,000 tonne fine ore bin (15 m × 15 m × 30 m). Oversize reports to a single 670 kW tertiary cone crusher in closed circuit, with discharge returning to the screen feed conveyor.
• Stage 2: Rod Mill/Ball Mill Grinding – Two parallel grinding lines each consist of a 3.8 m diameter by 4.6 m long rod mill and a similarly sized ball mill, each powered by 1120 kW motors. Belt feeders charge the rod mill, and combined mill discharge is pumped (150 kW duty/standby pumps) to a trio of 700 mm diameter hydrocyclones (2 duty, 1 standby per line). Cyclone underflow returns to the ball mill, while overflow gravitates to molybdenum rougher flotation.
• Stage 3: Molybdenum Flotation – Cyclone overflow feeds 14 × 30 m³ tank flotation cells per grinding line: the first seven cells perform molybdenum rougher flotation, and the remaining seven serve pyrite flotation for tungsten feed preparation. Rougher concentrate is classified, with underflow reground in an open-circuit M1000 IsaMill. Cleaner flotation uses two parallel 2.44 m diameter × 12 m tall first cleaner column cells, followed by a scavenger bank of four 30 m³ cells. Scavenger tails report to copper recovery; first cleaner concentrate undergoes three additional cleaning stages in 2.44 m × 12 m columns. Final concentrate is thickened in a 4 m diameter thickener, pressure-filtered, and bagged.
• Stage 4: Copper Flotation – Copper byproduct recovery from molybdenum cleaner scavenger tails uses two 5 m³ tank cells for rougher flotation and a single 2.44 m diameter column for upgrading. Column tails recirculate to copper rougher feed. Copper circuit tails report to final mill tails, while concentrate is thickened in a 4 m diameter thickener and pressure-filtered. This flowsheet is subject to further optimization in subsequent studies.
• Stage 5: Tungsten Gravity Recovery – Pyrite flotation tails from the molybdenum circuit are combined and fed to four batch centrifugal concentrators operating in parallel on an 11-minute cycle (three processing, one discharging). Primary concentrate passes a 106 µm vibrating slurry screen; oversize goes to two shaking tables, undersize to two additional shaking tables. All table concentrates are filtered and bagged for sale, while table tails recirculate to centrifuge feed.

Additional Interesting Data and Summary

The Davidson Project’s underground concentrator incorporates several notable technical features. The crushing circuit includes a 13,000-tonne coarse ore bin (17 m × 17 m × 30 m) and a 10,000-tonne fine ore bin (15 m × 15 m × 30 m). Secondary and tertiary cone crushers are each rated at 670 kW. The grinding circuit uses two parallel lines, each with a 3.8 m × 4.6 m rod mill and ball mill (1120 kW each), with cyclone classification. Molybdenum flotation employs 30 m³ tank cells (14 per line) for rougher and pyrite flotation, and column cells (2.44 m diameter × 12 m tall) for cleaning, complemented by an M1000 IsaMill for regrind. Copper flotation uses 5 m³ rougher cells and a single column. Tungsten recovery relies on four batch centrifugal concentrators operating on an 11-minute cycle, followed by 106 µm screening and four shaking tables. An XRF slurry analyser is budgeted for online grade estimation. Environmental considerations are central: the underground location minimizes surface footprint, and tailings are designed for 100% use as cemented paste backfill at approximately 75% solids. This is achieved by pressure filtering a portion of final tails to 80–85% solids and blending with the remaining thickener underflow. When underground voids are unavailable, thickened tailings are pumped to surface for filtration and dry stacking. Potential design risks include the need for smaller equipment due to drift size constraints, possible radioactive materials in the mineralization, and acid generation potential from sulphide oxidation. These risks are to be addressed in future prefeasibility and feasibility studies. The annual operating cost is estimated at $40.56 million CAD (2025), with major contributors being mill liners and media ($10.17M), maintenance consumables ($8.55M), manpower ($7.46M), and reagents ($6.86M). Manpower totals 55 personnel per shift across management, operations, and maintenance. The project’s economic significance lies in its multi-commodity recovery (molybdenum, copper, tungsten) and innovative underground processing that reduces haulage costs and environmental impact. Future development hinges on detailed engineering design, pilot-plant testing for tungsten recovery, and confirmation of geotechnical and geochemical characteristics.

Key Processes: Flotation, Gravity Separation, Ball Mill, Crushing

Target Commodities: Copper