Based on the June 12, 2020 NI 43-101 Preliminary Economic Assessment for Viva Gold Corp, this profile describes the conceptual processing route for the Tonopah gold project in Nye County, Nevada.
Report context
The 2020 Preliminary Economic Assessment (PEA) for the Tonopah Property, prepared by Gustavson Associates with an effective date of April 29, 2020, presents a conceptual process flowsheet for treating gold-bearing mineralized material from the project. The project encompasses 444 unpatented lode claims covering 8,762 acres approximately 20 miles northeast of Tonopah, Nevada. Process design and recovery estimates are based primarily on scoping-level metallurgical test work performed by McClelland Laboratories in 2019, as reported in “Report on Bottle Roll and Column Leach Testing – Midway Drill Core Composites, McClelland Laboratories, Inc. December 20, 2019.” The processing route described remains at a conceptual stage; the report recommends a detailed metallurgical program be undertaken before a prefeasibility study.
Processing route
Crushing and agglomeration
The conceptual process flowsheet involves three-stage crushing to produce a nominal product size of 80% passing 10 mesh. The crushed material will be agglomerated prior to placement on the leach pad. Conveyor transport will move the agglomerated material from the crushing plant to the stacking area, where a radial stacker will place it on the heap leach pad.
Heap leaching and solution recovery
The agglomerated, crushed material will be stacked and subjected to conventional heap leaching. The pregnant solution from the leach pad will be processed in an adsorption-desorption-refining (ADR) plant using a carbon-in-column (CIC) circuit to recover gold and silver.
Processing capacities
The planned processing capacity for the crushing and heap leach operation is 7,000 tonnes per day, equivalent to 2.5 million tonnes per year. The planned CIC circuit has a solution processing capacity of 400 cubic meters per hour and is equipped with a 2-tonne carbon strip circuit.
Reagent consumption projections
Reagent consumption estimates derived from the 2019 test work include:
- Cement consumption: 4.4 kg per tonne of material
- Sodium cyanide (NaCN) consumption: 0.42 kg per tonne, based on 60% of the consumption measured in column tests, weighted by material type
Key reported parameters
| Parameter | Value | Unit | Basis |
|---|---|---|---|
| Crushing product size | 80% passing 10 mesh | , | Proposed design specification |
| Crushing stages | 3 | , | Conceptual flowsheet |
| Crushing and heap leach feed rate | 7,000 | tonnes per day | Proposed design capacity |
| Annual feed rate | 2.5 | million tonnes per year | Proposed design capacity |
| CIC circuit solution processing capacity | 400 | cubic meters per hour | Proposed design capacity |
| Carbon strip circuit capacity | 2 | tonnes | Proposed design specification |
| Gold recovery , argillite | 83 | % | From column leach testing (2019); leaching still ongoing at termination |
| Gold recovery , volcanics | 58 | % | From column leach testing (2019); leaching still ongoing at termination |
| Blended recovery (50% argillite) | ~71 | % | Calculated estimate, not used as PEA design basis |
| Cement consumption | 4.4 | kg/t | Projected from test work |
| NaCN consumption | 0.42 | kg/t | Based on 60% of column test consumption, weighted by material type |
Project website: https://vivagoldcorp.com/projects/about-tonopah/
Project website: https://americanbatterytechnology.com/projects/tonopah-flats/
Note: Gold recovery projections have not been discounted from column results because gold leaching was still ongoing when the laboratory column test work was terminated. For the PEA, argillite and volcanic mineralized material are tracked separately with the anticipated recovery applied to each material type.
Technical qualifications
The processing information presented is derived from a Preliminary Economic Assessment (PEA) that is conceptual in nature and does not constitute a feasibility study or prefeasibility study. The metallurgical test work supporting the flowsheet and recovery projections is scoping-level, conducted on drill core composites from the Midway area. The report explicitly recommends that a more detailed metallurgical program be undertaken for any future prefeasibility study, including obtaining PQ core for column testing, crushing tests to produce feed for columns, column tests on each material type and blended material, evaluation of gold recovery as a function of particle size, and testing of high-pressure grinding rolls (HPGR) for the third crushing stage. All recovery, reagent consumption, and design parameters are based on the 2019 McClelland test work and PEA assumptions; they represent proposed or projected values, not demonstrated operational results. The PEA effective date is April 29, 2020, and the report date is June 12, 2020.
Source: *NI 43-101 Technical Report Preliminary Economic Assessment Tonopah Project, Nye County, Nevada*, prepared for Viva Gold Corp by Gustavson Associates, LLC, Project Number GU-1309723.003, effective date April 29, 2020, report date June 12, 2020. Relevant sections: 1.1–1.3 (property, ownership, geology), 17.1–17.5 (Recovery Methods).
