McIlvenna Bay Copper-Zinc Flotation: 4,900 tpd Recovery

Source: Eldorado Gold Corporation (2026)
Website: https://www.eldoradogold.com/assets/growth-projects/mcilvenna-bay-canada

Critical Data

Overview

Eldorado Gold Corporation operates the McIlvenna Bay Project, a proposed copper-zinc mine located in Saskatchewan, Canada. The project’s recovery methods are based on a conventional metallurgical flowsheet designed to treat 4,900 tonnes per day (1.789 million tonnes per annum) of ore from two primary mineralization zones: the CS Zone (copper sulphide stringer textures) and the MS Zone (higher zinc grades). The process plant, which is at an advanced design stage, incorporates a comminution circuit followed by sequential copper and zinc flotation to produce two saleable concentrates. A pyrite flotation circuit ensures tailings desulphurization, with non-sulphide tailings dewatered and filtered for paste backfill and surface stacking. This integrated approach maximizes metal recovery while minimizing environmental impact through water recycling and underground tailings storage. The plant’s significance lies in its ability to handle variable ore hardness—blending harder CS ore with softer MS ore—through a flexible grinding circuit that includes a SAG mill, pebble crusher, and ball mill. Copper and zinc rougher concentrates undergo regrinding in horizontal IsaMills to achieve fine particle sizes (P80 of 25 µm for copper, 20 µm for zinc) before multi-stage cleaning. Final concentrates are dewatered to 9% moisture using thickeners and pressure filters, ready for toll smelting. The recovery methods at McIlvenna Bay exemplify modern, environmentally responsible mineral processing tailored to complex polymetallic orebodies.

Key Process Stages

• Stage 1: Primary Crushing and Ore Storage – Run-of-mine ore is crushed to 100% passing 245 mm (P80 125 mm) using a jaw crusher. Crushed material is conveyed to a 2,500-t capacity ore bin providing 12 hours of live storage. Metal detection and dust collection systems ensure feed quality and safety.
• Stage 2: Grinding Circuit – A SAG mill (7.32 m diameter × 3.38 m EGL, 3,500 kW) in closed circuit with a pebble crusher and a ball mill (5.03 m × 7.85 m EGL, 3,500 kW) grinds ore to a cyclone overflow P80 of 75 µm. The SAG mill operates at 75% solids with 125 mm steel balls; the ball mill uses 50 mm balls at 31-35% charge. Circulating load is 300-350% of fresh feed.
• Stage 3: Copper Flotation and Regrind – Cyclone overflow enters agitated conditioning tanks before reporting to four 50 m³ tank cells for copper rougher flotation. Rougher concentrate is reground in a 500 kW IsaMill (M1000) to P80 25 µm, then cleaned in three stages (six 11.4 m³ cells for first cleaner, two for second, two for third). Final copper concentrate is pumped to dewatering.
• Stage 4: Zinc Flotation and Regrind – Copper flotation tailings feed the zinc circuit. After pH conditioning in two tanks, slurry passes through four 50 m³ rougher cells. Rougher concentrate is reground in two 500 kW IsaMills (M1000) to P80 20 µm, then cleaned in three stages (four 10 m³ first cleaner cells, three second, two third). Final zinc concentrate reports to dewatering.
• Stage 5: Concentrate Dewatering and Pyrite Flotation – Copper and zinc concentrates are thickened (6 m and 7 m diameter thickeners) to 55% solids, then filtered to 9% moisture using dedicated pressure filters. Filter cake is loaded into trucks for transport. Zinc rougher tailings undergo pyrite flotation (Jameson cell plus three tank cells) to recover sulphides for paste backfill. Non-sulphide tailings are thickened, filtered (15% moisture), and stacked at the surface facility.

Additional Interesting Data and Summary

The McIlvenna Bay recovery plant incorporates detailed design criteria that ensure robust operation across variable ore types. The SAG mill (7.32 m × 3.38 m EGL) operates with a steel charge of 125 mm balls at 7.6-16% volume and total load of 25%, using a variable-speed drive for flexibility. The ball mill (5.03 m × 7.85 m EGL) is rubber-lined with a 300% circulating load. Regrind circuits use horizontal IsaMills (M1000, 500 kW each) to achieve ultra-fine grinds—P80 25 µm for copper and 20 µm for zinc. Flotation equipment includes tank cells: four 50 m³ copper roughers (75 kW each), six 11.4 m³ copper cleaners (22 kW), four 50 m³ zinc roughers (75 kW), and four 10 m³ zinc cleaners (22 kW). The pyrite circuit employs one Jameson cell followed by three conventional tank cells, with a mass pull of 34%. For dewatering, copper and zinc concentrates are thickened in 6 m and 7 m high-rate thickeners respectively, underflow at 55% solids, then filtered to 9% moisture via dedicated pressure filters. The paste plant handles 47% of mill feed (non-sulphide tailings), producing filter cake at 15% moisture for surface stacking. Environmental considerations are central: tailings desulphurization minimizes acid rock drainage, and paste backfill reduces surface footprint. Water is recycled from thickeners and filter filtrate, with makeup from filtered process water. Economic impact is significant—two saleable concentrates (copper and zinc) are produced for toll smelting, with surge capacities of 10.5 hours (copper) and 8.4 hours (zinc). Sustainability initiatives include low-energy IsaMills, closed water circuits, and dust collection systems. The project is in the feasibility/engineering stage, with a flowsheet that can blend ore types (62% CS, 38% MS) to maintain consistent feed grades. Future outlook includes potential optimization of regrind circuits and reagent dosages based on on-stream analyzer feedback (Cu, Zn, Fe). Overall, the recovery methods demonstrate a modern, integrated approach to polymetallic sulphide processing with strong environmental stewardship.

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

Target Commodities: Gold, Copper, Zinc