This profile describes Fosterville Gold Mine in Victoria, Australia. The former article titled “Mineral Processing Circuit of Kirkland Lake” described Fosterville’s plant, not a separate mine at Kirkland Lake; its processing information is consolidated here.
Processing circuit
The source records describe crushing and SAG milling, gravity recovery, flotation, concentrate regrinding, biological oxidation, neutralization and washing, followed by carbon-in-leach and heated-leach treatment. Gold is recovered through carbon elution, electrowinning and smelting.
Equipment reported in the historical sources
The records identify a 760 × 1,372 mm jaw crusher, a 6.1 m diameter SAG mill rated at 3,500 kW, six biological-oxidation reactors, and six 190 m³ CIL tanks. Flotation concentrate is reground to approximately 20 µm before oxidation. Heated leaching addresses preg-robbing behavior.
How to read the recovery figures
These source descriptions include data from different years and individual process stages. Gravity, flotation and biological-oxidation performance percentages are not interchangeable with overall plant gold recovery. The historical records are preserved below with their original context; they do not establish present-day plant performance.
Dated source records
The original source descriptions are retained for traceability. Where figures differ, use the reporting period and measurement basis described above.
Mineral Processing Circuit of Fosterville Mine
Processing and Recovery Methods
The Fosterville Gold Mine employs a comprehensive and multi-stage processing circuit designed to maximize gold recovery from sulfide-bearing ores. The plant, commissioned in 2004, integrates crushing, grinding, gravity recovery, flotation, bio-oxidation (BIOX®), leaching, and specialized heated leach circuits.
1. Crushing and Milling
– Primary Crushing: ROM ore is crushed via a 760mm x 1,372mm single-toggle jaw crusher (90mm product size) with dust suppression systems.
– SAG Milling: A 3,500kW SAG mill (6.1m diameter x 6.1m length) grinds ore to P80 of 75µm in closed circuit with hydrocyclones. Design throughput: 120 dry tph (24/7 operation).
– Gravity Circuit: Recovers coarse gold from the grinding circuit recirculating load using Knelson concentrators and Gemini shaking tables.
2. Flotation
– Circuit Design: Rougher-scavenger-cleaner configuration to produce a gold-bearing sulfide concentrate (~8–10% of feed mass, grading ~20% S₂).
– Reagents: Copper sulfate (activator), potassium amyl xanthate (PAX, collector), and frother.
– Regrind: Concentrate is reground to 80% passing 20µm before thickening and feeding to BIOX®.
3. Gravity Recoverable Gold (GRG) Circuit
– Added in 2016 to target visible gold, with upgrades in 2018.
– Primary: Knelson concentrators process 100% of regrind recirculating load.
– Secondary/Tertiary: Gemini GT1000 and GT250 tables refine concentrates, with final product calcined and smelted.
4. Bio-Oxidation (BIOX®)
– Process: Oxidizes sulfide minerals to liberate gold via bacterial action (pH 1.0–1.6, 43°C).
– Key Features:
– Six reactors with cooling coils and medium-pressure aeration.
– Nutrient control: Nitrogen (N), potassium (K), phosphorous (P).
– Material Handling: SAF 2205 stainless steel used due to corrosive slurry.
– CCD Circuit: Three-stage counter-current decantation (wash ratio 4.0) removes solubilized arsenic/acid.
5. Leaching (CIL & Heated Leach)
– CIL Circuit: Six 190m³ tanks (48-hour residence, 30% pulp density) with 20–30g/L activated carbon.
– Heated Leach (HL): Unique to Fosterville, uses steam/caustic to combat preg-robbing (six 75m³ tanks, 8–12 hours).
– Recovery Rates:
– CIL recovery: 86–97% (2018 peak).
– Overall plant recovery: 85–97.3% (2018).
6. Elution and Smelting
– Pressure Zadra Elution: Strips gold from carbon; electrowinning and smelting produce doré bars.
Technical Specifications & Equipment
– SAG Mill: 3,500kW, 6.1m x 6.1m.
– Flotation Regrind Mill: 8ft x 13ft ball mill.
– BIOX® Reactors: 48-hour surge capacity, chloride tolerance <1,000ppm.
– Neutralization: Ground limestone/lime slurry for gypsum/ferric arsenate precipitation.
Throughput & Capacity
– Nominal Capacity: 830,000 tpa (2018: 456,909 tonnes milled).
– Expansion Potential: Space for doubling throughput via duplicate facilities.
Innovations & Challenges
– Heated Leach: Addresses preg-robbing by native carbon (in-house technology).
– Gravity Circuit Upgrades: Improved recovery of coarse gold (2016–2018).
– BIOX® Optimization: Strict chloride/cyanide management to protect bacterial culture.
Key Challenges & Solutions
– Preg-Robbing: Mitigated via HL circuit.
– BIOX® Sensitivity: Controlled water quality and separate reagent streams.
– Tailings Management: Dual residue streams (flotation/CIL) with in-pit storage for cost efficiency.
Recovery Performance (2018 Highlights)
– Overall Plant Recovery: 97.3% (up from 85% in 2009).
– Gold Produced: 356,230 oz (2018, vs. 102,336 oz in 2009).
The Fosterville circuit combines conventional and innovative methods to achieve industry-leading recoveries, supported by scalable infrastructure and rigorous process controls.
Technical report and processing history
The following archived source profiles have been consolidated here to preserve the project’s processing history and study context.
Fosterville Gold Mine — 2018 Technical Report
Fosterville Gold Mine — 2018 Technical Report
| Company | Kirkland Lake Gold |
| Date | 2018 |
| Region | Australia |
| Commodities | Gold |
| Mine Type | Underground |
| Throughput | 120 dry tph |
| Status | Operating |
Executive Summary
The Fosterville Gold Mine processing plant has been operational since commissioning in 2004, with all processing models based on actual plant performance data. The processing budget accounts for the mining schedule, including ore source location, tonnes to be mined, gold grade, and predicted sulfur grades. Recovery data from 2009 to 2018 demonstrates consistent operational stability with improving recovery rates over time.
The process plant incorporates a comprehensive suite of unit operations designed to treat sulphide ore. Key stages include single stage crushing with a primary jaw crusher, semi-autogenous grinding (SAG) milling, and a flotation circuit to produce a gold-bearing sulfide concentrate. The concentrate undergoes gravity concentration, bio-oxidation (BIOX®), and carbon-in-leach (CIL) processing. A unique Heated Leach (HL) circuit is utilized to combat preg-robbing capabilities of non-carbonaceous carbon present in the orebody.
Performance metrics from 2009 to 2018 show a significant increase in overall plant recovery, rising from 85.0% to 97.3%. Throughput varied annually, with 2018 recording 456,909 tonnes milled. The plant layout allows for future capacity expansion, including space for additional tank farms and equipment to double throughput if required. No processing factors or deleterious elements are anticipated to significantly affect economic extraction.
Reports
Website: https://www.agnicoeagle.com/English/operations-and-projects/global-operations-and-development-projects/fosterville/default.aspx
Report Date: 2018
Region: Australia
Project Status: Operating
Commodity: Gold
Throughput: 120 dry tph
Mine Life:
Mine Type: Underground
Ore type:
Fosterville Gold Mine — 2017 Technical Report
Fosterville Gold Mine — 2017 Technical Report
| Company | Kirkland Lake Gold |
| Mine | Fosterville Gold Mine |
| Date | December 2017 |
| Region | Victoria, Australia |
| Commodities | Gold |
| Mine Type | Underground |
| Throughput | 2,880 tpd (120 tph) |
| Mine Life | Not stated in report |
| Annual Production | 263,845 oz (2017) |
| Status | Operating |
Executive Summary
The Fosterville Gold Mine is a refractory gold operation located in Victoria, Australia. The processing plant was commissioned in November 2004 with first gold production in Q1 2005. The mine employs a complex flowsheet incorporating crushing, grinding, flotation, bio-oxidation (BIOX®), carbon-in-leach (CIL) leaching, and heated leach circuits to recover gold from sulfide ores. The plant has a design throughput of up to 120 dry tph, processing ore through a single-stage jaw crusher, SAG mill, and flotation circuit to produce a gold-bearing sulfide concentrate. The BIOX® circuit oxidizes the concentrate to release gold from the sulfide matrix, followed by CIL and heated leach for final gold recovery. Production has increased significantly, with 263,845 oz of gold produced in 2017 at an overall plant recovery of 95.0%.
Operational Details
Processing Profile
- Crushing: Single toggle jaw crusher (760mm x 1,372mm), 80% design availability
- Milling: 6.1m x 6.1m SAG mill (3,500kW), P80 of 75µm
- Flotation: Rougher-scavenger cleaner circuit, produces 8-10% concentrate
- Regrind: 8ft diameter x 13ft length mill, P80 of 20µm
- Gravity: Knelson concentrator, Gemini GT1000 and GT250 tables
- Oxidation: BIOX® bio-oxidation reactors
- CCD: Three-stage CCD, wash ratio 4.0
- Neutralization: Limestone grinding (wet ball mill), six neutralization tanks
- Leaching: CIL (six 190m³ tanks, 48 hours residence), Heated Leach (six 75m³ tanks)
- Elution: Pressure Zadra elution (3.5t), electro-winning, smelting to doré
Recovery Data (2017)
- Flotation Recovery: 98.6%
- Gravity Recovery: 27.6%
- BIOX® Recovery: 98.7%
- Sulfide Oxidation: 97.3%
- CIL Recovery: 93.9%
- Heated Leach Recovery: 2.4%
- Overall Leach Recovery: 96.2%
- Overall Plant Recovery: 95.0%
Reports
Website: https://www.agnicoeagle.com/English/operations-and-projects/global-operations-and-development-projects/fosterville/default.aspx
Report Date: December 2017
Region: Victoria, Australia
Project Status: Operating
Commodity: Gold
Throughput: 2,880 tpd (120 tph)
Mine Life: Not stated in report
Mine Type: Underground
Ore type:
Fosterville Gold Mine — 2015 Technical Report
Fosterville Gold Mine — 2015 Technical Report
| Company | Newmarket Gold |
| Mine | Fosterville Gold Mine |
| Date | 2015 |
| Region | Victoria, Australia |
| Commodities | Gold |
Executive Summary
The Fosterville Gold Mine, operated by Newmarket Gold, utilizes a complex processing circuit designed to handle refractory sulphide ores. Since commissioning in 2004, the plant has undergone various upgrades, including the implementation of specialized Bio-oxidation (BIOX) and Heated Leach circuits to manage gold recovery from complex mineral matrices and mitigate preg-robbing characteristics of the mill feed.
The processing plant achieves gold recovery through a combination of traditional comminution and flotation followed by advanced hydrometallurgical techniques. Key operational success is attributed to the BIOX circuit, which oxidizes the sulphide mineral matrix, and the subsequent Carbon-in-Leach (CIL) and Heated Leach circuits, which maximize gold extraction efficiency from both fresh ore and previously retreated leach tails.
Website: https://en.wikipedia.org/wiki/Fosterville_Gold_Mine
Report Date: 2015
Region: Victoria, Australia
Project Status:
Commodity: Gold
Throughput:
Mine Life:
Mine Type:
Ore type:
Mineral Processing Circuit of Kirkland Lake
1. Processing and Recovery Methods
The Fosterville Gold Mine employs a sophisticated processing circuit combining gravity recovery, flotation, bio-oxidation (BIOX®), carbon-in-leach (CIL), and heated leach (HL) to maximize gold recovery from refractory sulfide ores.
2. Key Unit Operations & Technical Specifications
– Crushing & Milling:
– Primary Jaw Crusher: 760mm x 1,372mm, producing 90mm crushed ore.
– SAG Mill: 6.1m diameter x 6.1m length (3,500 kW), grinding to P80 of 75µm in closed circuit with hydrocyclones.
– Throughput: Up to 120 dry tph, operating 24/7.
– Gravity Recovery:
– Knelson Concentrators: Installed in 2016 to recover coarse gold from SAG mill recirculating load.
– Shaking Tables (Holman 8000, Gemini GT1000/GT250): Upgrade in 2018 improved gravity recovery.
– Recovery Rates: Gravity recovery ranged from 12.9% (2017) to 99.2% (2018) depending on ore type.
– Flotation Circuit:
– Rougher-Scavenger-Cleaner setup producing a gold-bearing sulfide concentrate (8–10% of feed mass, ~20% S₂ grade).
– Regrind Mill: 8ft x 13ft, regrinding concentrate to 80% passing 20µm.
– Reagents: Copper sulfate (activator), potassium amyl xanthate (PAX, collector), and frother.
– Flotation Recovery: Consistently 95–97% (2014–2018).
– Bio-Oxidation (BIOX®):
– Oxidation of sulfide concentrate to liberate gold.
– 6 BIOX® reactors (pH 1.0–1.6, temp ~43°C, SAF 2205 stainless steel construction).
– Oxygen & Cooling: Medium-pressure air injection and cooling coils maintain optimal conditions.
– Sulfide Oxidation Efficiency: 93.9–98.8% (2017–2018).
– CCD & Neutralization:
– 3-stage Counter-Current Decantation (CCD) with wash ratio of 4.0 to remove solubilized arsenic/acid.
– Neutralization Circuit: Uses limestone/lime to precipitate gypsum and ferric arsenate.
– Leaching (CIL & Heated Leach):
– CIL Circuit: Six 190m³ tanks (48h residence time, 30% pulp density, 20–30g/L carbon).
– Heated Leach (HL): Six 75m³ tanks (8–12h residence, steam injection) to combat preg-robbing.
– Overall Leach Recovery: 95–97.3% (2017–2018).
– Elution & Smelting:
– Pressure Zadra Elution: 3.5t capacity, acid wash + stainless steel columns.
– Electrowinning & Smelting: Produces doré bars (refined at ABC Refinery, NSW).
3. Recovery Rates & Efficiencies (2009–2018)
– Overall Plant Recovery: Improved from 85% (2009) to 97.3% (2018) due to circuit optimizations.
– BIOX® Recovery: Consistently >97% post-2014.
– Heated Leach Contribution: Added 2–7.1% recovery (critical for preg-robbing ores).
4. Notable Innovations
– Heated Leach Circuit (2009): Proprietary in-house technology to address carbonaceous ore challenges.
– Gravity Circuit Upgrades (2016–2018): Enhanced coarse gold recovery via Knelson concentrators and shaking tables.
– In-Pit Tailings Storage: Reduced environmental footprint and costs.
5. Capacity & Throughput
– Nominal Capacity: 830,000 tpa (plant designed for expansion to double throughput).
– Actual Milling (2018): 456,909 tonnes at 24.93 g/t Au feed grade.
6. Key Challenges & Solutions
– Preg-Robbing Ore: Mitigated via heated leach circuit.
– BIOX® Sensitivity: Strict control of chlorides (<1,000ppm) and cyanide to protect bacteria.
– Tailings Management: Segregation of flotation/CIL residues and use of lined storage facilities.
—
Conclusion
The Fosterville processing circuit is a high-efficiency, multi-stage system integrating crushing, grinding, flotation, bio-oxidation, and advanced leaching to achieve >97% gold recovery. Innovations like the heated leach and gravity upgrades have significantly enhanced performance, while modular plant design allows future expansion.
