Company: AngloGold Ashanti
Effective Date: 31 December 2025
Report Type: Pre-Feasibility Study
Location: Nevada, USA
Executive Summary
The Arthur Gold Project, centered on the Merlin deposit, is a gold-silver project located in Nevada, USA. The project employs a dual-processing strategy utilizing both conventional milling with carbon-in-leach (CIL) cyanidation and heap leaching with carbon-in-column (CIC) technology. The processing methods were selected based on ore characteristics, with higher-grade materials routed to the milling circuit and lower-grade materials processed via heap leach. The Merlin ore is strongly oxidised with gold recoveries increasing with decreasing feed size. Significant gravity-recoverable gold is present in higher-grade zones, with gravity circuit testwork indicating recovery of up to 50% of contained gold.
The mill process plant is designed for 7,000,000 t/a throughput, utilizing a three-stage crushing circuit (Gyratory-Cone-HPGR) followed by a single large ball mill (8.28 m diameter x 12.8 m EGL, 18,400 kW) operating in closed circuit with hydrocyclones. The grinding circuit produces a P80 of 106µm. The CIL circuit consists of 16 tanks across two parallel trains with carbon concentration maintained at 15g/L. Gold and silver are recovered through pressure Zadra elution, electrowinning, and smelting to produce doré bars. The heap leach operation processes 5,500,000 t/a through similar crushing, with ore agglomerated using cement before stacking on a lined pad. Pregnant solution is processed through vertical CIC units before transfer to the centralized ADR plant.
Processing Details
Mill Process Plant (7 Mt/a)
- Crushing: Three-stage (Gyratory-Cone-HPGR)
- Primary: 42×65 gyratory crusher (373 kW)
- Secondary: MP1000 cone crusher (746 kW)
- Tertiary: HRC2000e HPGR (4,040 kW)
- Grinding: Single ball mill (8.28m x 12.8m EGL, 18,400 kW) with hydrocyclones
- Gravity: Centrifugal concentrators with intensive leach reactor (ILR)
- Leaching: 16-tank CIL circuit (2 parallel trains)
- Elution: Pressure Zadra process
- Gold Recovery: Electrowinning and smelting to doré
Heap Leach Operation (5.5 Mt/a)
- Crushing: Three-stage (Gyratory-Cone-HPGR)
- Agglomeration: Drum agglomerator with cement
- Leaching: 65-day average leach cycle
- Adsorption: Vertical CIC units
- Solution Application: Drip emitters on lined heap pad
Key Parameters
- Mill Throughput: 19,178 t/d (design)
- Heap Leach Throughput: 15,068 t/d
- Mine Life: LOM production of 4,526,000 oz Au and 1,466,000 oz Ag
- Tailings: Filtered and dry-stacked (filtered TSF)
References
- NI 43-101 Technical Report, Effective Date: 31 December 2025
Website: https://www.anglogoldashanti.com/portfolio/americas/united-states-projects/
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