The Mount Polley Mine employs a conventional mineral processing circuit designed for the production of copper-gold concentrate. The mill, commissioned in June 1997, integrates crushing, grinding, flotation, and dewatering stages with a throughput capacity ranging between 17,800 to 22,000 tonnes per day (tpd), contingent on ore hardness.
Processing and Recovery Methods:
1. Crushing Circuit:
– Three-stage crushing (primary, secondary, tertiary) reduces ore to 16 mm for grinding.
– Equipment:
– Primary: 1 × 42” x 65” gyratory crusher.
– Secondary: 1 × 7’ standard cone crusher.
– Tertiary: 3 × short-head cone crushers + 4 screen decks.
– Ore Handling: Crushed product stored in a 15,000 t stockpile; pebble mill feed held in a 2,000 t surge pile.
2. Grinding Circuit:
– Rod mills process crusher product at 915 t/h, reducing feed size for subsequent ball mills.
– Ball and pebble mills further grind material to 65% passing 200 mesh (flotation feed size).
– Classification: Hydrocyclones and pumps optimize particle size distribution.
– Power & Water:
– Electricity sourced via a 69 kV line from Soda Creek substation (70 km).
– Water reclaimed from tailings pond.
3. Flotation Circuit:
– Hybrid system combining column and mechanical cells for rougher/scavenger concentrate recovery.
– Regrinding and cleaning stages enhance concentrate grade.
– Flexibility: Designed to handle variations in ore head grade and oxidation.
– Reagents:
– Potassium amyl xanthate (15 g/t) – Collector.
– POLYFROTH® W22C (20 g/t) – Frother.
– Flocculant (0.13 g/t) and Lime (90 g/t) – pH control and settling aid.
4. Concentrate Dewatering:
– Thickening: Concentrate stored in surge tanks.
– Filtration: Two Larox pressure filters reduce moisture to 8% for transport.
– Storage: Conveyor system loads filtered concentrate into trucks.
5. Instrumentation & Control:
– Centralized PLC system with remote I/O stations for real-time monitoring.
– On-Stream Analyzer (OSA): X-ray spectrometer assays five process streams for metallurgical control, reducing manual sampling needs.
– Human-Machine Interface (HMI): Displays grinding/flotation circuit data for operator adjustments.
6. Concentrate Transport:
– Trucked to Port of Vancouver via Arrow Transportation Systems.
– Shipped to Asian smelters; sales contracts negotiated dynamically.
Key Technical Specifications & Innovations:
– Pebble Mill Integration: Unique use of pebble milling post-ball milling for finer grind.
– Hybrid Flotation: Combines column/mechanical cells for improved recovery flexibility.
– OSA Integration: Automated assay feedback optimizes flotation performance.
Throughput & Efficiency:
– Design Capacity: 17,800–22,000 tpd (ore hardness-dependent).
– Grinding Rate: ~915 t/h in rod mills.
– Final Concentrate Moisture: 8% (achieved via Larox filters).
Challenges & Solutions:
– Ore Variability: Circuit designed to adapt to head grade/oxidation changes via flexible flotation.
– Tailings Management: Temporary deposition in Springer Pit (permit-limited); long-term storage in TSF post-2016.
The Mount Polley circuit exemplifies a robust, conventional flowsheet with targeted innovations (OSA, hybrid flotation) to enhance operational efficiency and adaptability.
Technical report and processing history
The following archived source profiles have been consolidated here to preserve the project’s processing history and study context.
Mount Polley — 2016 Technical Report
Mount Polley — 2016 Technical Report
| Company | Mount Polley Mining Corp |
| Date | 2016 |
| Region | British Columbia, Canada |
| Commodities | Copper, Gold |
Executive Summary
The Mount Polley mill was commissioned in June 1997 and utilizes a conventional rod and ball mill circuit with flotation and dewatering to produce copper and gold concentrates. The facility has a processing capacity ranging from 17,800 to 22,000 tonnes per day depending on ore hardness. Concentrates are trucked to the Port of Vancouver for shipment to overseas smelters.
The crushing circuit operates in three stages to produce a 16 mm product for the grinding circuit, stored in a 15,000 t stockpile. Equipment includes a 42 x 65 gyratory crusher, standard and short head cone crushers, and screen decks. Grinding involves rod mills, ball mills, and a pebble mill, reducing ore to 65% passing 200 mesh for flotation.
Flotation utilizes a combination of column and mechanical cells to recover rougher and scavenger concentrates, which are cleaned to produce high-grade products. Reagents include potassium amyl xanthate, POLYFROTH W22C, flocculant, and lime. Final concentrate is dewatered using pressure filters to 8% moisture before shipment.
Reports
Website: https://imperialmetals.com/our-operations/mount-polley-mine
Report Date: 2016
Region: British Columbia, Canada
Project Status:
Commodity: Copper, Gold
Throughput:
Mine Life:
Mine Type:
Ore type:
Mount Polley Mine: Copper/Gold Flotation Processing Circuit
Overview
The Mount Polley mill is a conventional copper/gold processing facility commissioned in June 1997. The plant features a comprehensive crushing, grinding, flotation, and dewatering circuit capable of processing 17,800 to 22,000 tonnes per day (tpd) of ore. Final concentrate is trucked to Vancouver for overseas shipment to smelters.
Key Process Stages
- Crushing Circuit: Three-stage crushing system producing 16mm feed (42″x65″ gyratory crusher, 7′ standard cone, three short-head cones, four screen decks)
- Grinding Circuit: Rod mill (915 tph capacity) feeding ball mills and pebble mill to achieve 65% passing 200 mesh
- Flotation Circuit: Combination of column and mechanical cells for rougher/scavenger concentration with regrind and cleaning stages
- Dewatering: Thickeners and two pressure filters producing concentrate at 8% moisture content
- Control System: Central PLC with remote I/O stations and on-stream X-ray analyzer for five process streams
Critical Data
| Parameter | Value |
|---|---|
| Design Throughput | 17,800-22,000 tpd |
| Rod Mill Capacity | 915 tph |
| Final Grind Size | 65% passing 200 mesh |
| Concentrate Moisture | 8% |
| Crushed Ore Storage | 15,000 t stockpile |
| Pebble Feed Storage | 2,000 t surge pile |
Process Reagents
| Reagent | Dosage |
|---|---|
| Potassium amyl xanthate | 15 g/t |
| POLYFROTH® W22C | 20 g/t |
| Flocculant | 0.13 g/t |
| Lime | 90 g/t |
Infrastructure
The plant receives power via a dedicated 70km, 69kV line from Soda Creek station. Process water is reclaimed from tailings ponds. Concentrate is transported to Vancouver by truck for overseas shipment.
