The Brunswick Processing Plant processes antimony and gold-rich sulphide ore through a conventional comminution and flotation concentrator. Operational since 2007 and under Mandalay Resources since 2009, the plant has undergone upgrades to achieve a current throughput of ~13,000 dry metric tonnes (dmt)/month.
Processing and Recovery Methods:
1. Crushing & Screening Circuit:
– Equipment: Two diesel-powered Finlay I-130RS mobile impact crushers (duty + standby) in closed circuit with a 12 mm vibrating screen.
– Output: Crushed ore (≤12 mm) is stored in two 120-tonne fine ore bins.
– Throughput: 13,000 dmt/month (peak: 14,000 dmt/month).
– Upgrades: A third Finlay I-140RS crusher (planned for 2022) will transition crushing to a two-stage operation.
2. Milling Circuit:
– Configuration: Two ball mills in series (primary and secondary), both closed-circuit.
– Primary Mill: Operates with a Dutch State Mines (DSM) screen; oversize returns for regrinding, undersize feeds a centrifugal gravity concentrator.
– Gravity Recovery:
– Recovers high-grade gold concentrate (40–55% recovery from Youle ore).
– Upgraded via shaking table and sold directly to refineries.
– Target Grind: P80 of 60 µm.
– Secondary Mill: Cyclone underflow regrinds material, while overflow feeds flotation.
3. Flotation Circuit:
– Feed: Cyclone overflow conditioned with lead nitrate (activator) and potassium amyl xanthate (PAX, collector).
– Equipment:
– Two 48-inch StackCell® roughers + two rougher tank cells (series).
– Original Denver DR100 (8 cells for rougher/scavenger) and DR15 (6 cells for cleaning).
– Two Eriez CavTube® columns (added April 2021) for low-grade Sb-Au recovery.
– Process Flow:
– Rougher/scavenger concentrates report to cleaners; tailings go to thickeners.
– CavTube® columns process scavenger tailings, improving recovery.
4. Concentrate Handling:
– Thickening: Two concentrate thickeners (primary + CavTube® product).
– Filtration: Plate-and-frame pressure filter dewaters concentrate; filtrate recycled.
– Product: Bagged Sb-Au concentrate shipped overseas; gold concentrate sold separately.
5. Tailings Management:
– Thickened tailings pumped to two TSFs (east and north of plant).
– Water recovery: Thickener overflow and TSF decant recycled.
Key Metrics:
– Throughput: 12,500–13,000 dmt/month (avg.), peaking at 14,000 dmt/month.
– Recoveries (2021):
– Antimony (Sb): 94.6%
– Gold (Au): 93%
– LoM Forecast (2022): 94.1% Sb, 92.7% Au.
Innovations & Upgrades:
– StackCell® and CavTube® Flotation: Enhanced recovery (commissioned 2021).
– Water Management: Reverse osmosis (RO) plant (2 ML/day) + aquifer recharge trials.
– Power Optimization: Consolidated electrical supply (2019) with backup generation.
Challenges & Solutions:
– Feed Variability: Adjusted recovery algorithms for Youle ore (post-2021 data).
– Capacity Constraints: Crusher upgrades (2022) to mitigate wet-season bottlenecks.
– Filtration Redundancy: Second filter press planned for 2022.
The plant’s robust design and incremental upgrades ensure efficient processing of Costerfield’s remaining ore reserves, supported by 14+ years of operational data.
