The Brunswick processing plant is the concentrator for Alkane Resources’ Costerfield gold-antimony operation in central Victoria, Australia. It is not a separate Brunswick mine. The plant receives high-grade underground ore from deposits in the Costerfield district and uses crushing, two-stage ball milling, gravity concentration and sulphide flotation to produce separate gold and antimony-gold concentrate products. This profile consolidates MillMatters’ duplicated Brunswick plant pages and distinguishes the historical 2021–22 operating data from current owner information.
| Owner | Alkane Resources, 100%, following its August 2025 merger with Mandalay Resources |
|---|---|
| Operation | Costerfield gold-antimony operation |
| Location | Central Victoria, Australia; approximately 50 km east of Bendigo |
| Feed sources | Underground deposits in the Costerfield district, including Augusta, Cuffley, Brunswick, Youle and Shepherd |
| Commodities | Gold and antimony |
| Plant route | Crushing and screening, two-stage ball milling, gravity gold recovery, antimony-gold sulphide flotation, concentrate filtration and tailings storage |
| Current owner-stated plant capacity | 140,000 t/a |
| Profile last reviewed | August 30, 2026 |
Brunswick processing flowsheet
Costerfield ore is narrow-vein, high-grade material containing gold and antimony-bearing sulphides. The plant first removes liberated gravity gold, then floats the remaining antimony-gold sulphide minerals into a saleable concentrate. This split route is important: the gravity product is sold directly to a refinery, whereas the flotation product is thickened, filtered and shipped as concentrate.
1. Crushing, screening and fine-ore storage
Historical plant descriptions identify two diesel-powered Finlay I-130RS mobile impact crushers in duty-and-standby service, operating in closed circuit with a 12 mm vibrating screen. Crushed material is stored in two fine-ore bins of approximately 120 t each before milling. Earlier planning described a third Finlay I-140RS crusher to create a two-stage crushing configuration; this is retained here as historical upgrade context rather than assumed current equipment status.
2. Two-stage ball milling and gravity recovery
Two ball mills operate in series with classification. The primary mill uses a Dutch State Mines screen: screen oversize returns for additional grinding and the undersize feeds centrifugal gravity concentration. Historical reports identify gravity recovery of approximately 40–55% of gold from Youle ore, followed by upgrading on a shaking table. The secondary mill operates with cyclones and produces flotation feed near a P80 of 60 µm.
3. Antimony-gold flotation
Cyclone overflow is conditioned with lead nitrate and potassium amyl xanthate (PAX) before rougher and scavenger flotation. The circuit includes two 48-inch StackCell roughers, two rougher tank cells, Denver DR100 rougher/scavenger cells and DR15 cleaner cells. Two Eriez CavTube columns commissioned in 2021 treat a lower-grade stream or scavenger tailings to recover additional antimony-gold sulphide concentrate.
4. Concentrate handling
Flotation products are thickened and dewatered in a plate-and-frame pressure filter. Filter cake is bagged for export, while filtrate returns to the process-water circuit. Gold-rich gravity concentrate is handled separately and sold directly to a refinery.
Principal equipment and historical operating data
| Area | Equipment or parameter | Reported value or configuration |
|---|---|---|
| Current plant capacity | Alkane operation profile | 140,000 t/a |
| Historical plant rate | 2021–22 report basis | Approximately 12,500–13,000 dry t/month; peaks near 14,000 dry t/month |
| Crushing | Mobile impact crushers and screen | Two Finlay I-130RS units, duty and standby; 12 mm screen |
| Fine-ore storage | Bins | Two × approximately 120 t |
| Primary milling | Ball mill with DSM screening | Gravity recovery from screen undersize |
| Secondary milling | Ball mill and cyclones | Flotation feed target P80 approximately 60 µm |
| Gravity | Centrifugal concentrator and shaking table | Historical Youle recovery approximately 40–55% of gold to gravity |
| Flotation | StackCell, conventional cells and CavTube columns | Antimony-gold sulphide recovery and cleaning |
| Water treatment | Reverse-osmosis plant | Historical description cites approximately 2 ML/d capacity |
The historical monthly-rate and recovery values are not current plant guidance. They are retained to explain the original circuit and its ore-specific performance.
Gold and antimony products
The circuit produces two distinct saleable streams. Free or readily liberated gold recovered by the gravity circuit is upgraded on a shaking table and sold as high-grade gold concentrate. The flotation circuit produces an antimony-gold sulphide concentrate that is dewatered, bagged and marketed to third parties. This process arrangement is why Costerfield can recover both a precious metal and a critical mineral from the same narrow-vein ore system.
Tailings and water management
Thickened flotation tailings are pumped to the Brunswick and Bombay tailings-storage facilities. Process-water recovery comes from thickener overflow and tailings decant, while underground dewatering provides a significant additional water source. Historical operating material also describes reverse-osmosis treatment and evaporation management for surplus or affected water. These systems remain integral to sustaining the small, high-grade plant rather than being separate ancillary facilities.
How to read the capacity and recovery figures
The former duplicate pages mixed several reporting periods. Their 12,500–13,000 dry-t/month and 2021 recovery values describe a historical operating basis; the reported 2022 crusher and filter upgrades were plans, not evidence that all equipment had been installed. Alkane’s current Costerfield profile, published after its merger with Mandalay, identifies the operating Brunswick plant at 140,000 t/a. The two capacity figures should therefore be treated as different reporting bases rather than simultaneous guarantees.
Similarly, Costerfield production and guidance belong to the overall mine operation, not necessarily to one plant campaign. Alkane reports 2024 production of 43,300 oz gold and 1,300 t antimony from Costerfield, with FY2026 guidance of 40,000–45,000 oz gold and 800–900 t antimony. Ore sequencing, grade and the mix of Youle and Shepherd feed can change these outcomes without altering the basic gravity-plus-flotation route.
Technical-report library and sources
| Source period | How it is used in this profile |
|---|---|
| Historical 2021–22 plant descriptions | Crushing, milling, gravity, flotation, filtration, water-treatment configuration and ore-specific recovery context |
| Mandalay 2024/2025 technical-report materials | Costerfield reserves, operating context and plant-capital program before the merger |
| Alkane Resources 2025 annual report and current Costerfield profile | Current ownership, 140,000 t/a plant capacity, district feed sources and current production/guidance context |
Additional resources and industry links
- Alkane Resources: Costerfield operation profile
- Mandalay Resources 2024 Annual Information Form (PDF)
- MillMatters: Gravity concentration equipment and circuit guide
- MillMatters: Dewatering equipment and circuit guide
- MillMatters: Mine tailings management guide
