Hochschild’s Volcan Mining Project located in northern Chile is a new play with 389.7 million tonnes of Measured and Indicated resources grading 0.709 g/tonne of gold, containing 8.88 million ounces of gold. The site, located high in the Andes mountains has limited water available. Because of its remote location, water conveyance to the site is very problematic and economically unattractive. As the traditional method of extracting gold from bulk ore by heap leaching requires substantial quantities of water with significant water losses occurring through evaporation, Hochschild seeks an alternative process.
Hochschild is interested in developing processes to extract gold ore that are cost-effective and eliminate, or at least minimize, the dependency on water.
Since none of the ore has been mined yet, this project is a “clean slate” opportunity to propose novel methods for gold extraction.
See Table 1 for typical characteristics of the Volcan ore. Composition of the ore in the play varies by location, but this table defines characteristic ranges for composition. The ore has about 0.7 g of gold per tonne, with gold particles ranging from 5 to 15 µm. About 75% of the gold present is trapped within a quartz matrix.
Table 1. Mineralogical Composition of Volcan Ores. Columns represent samples from different locations.
The pre-feasibility study of the project states:
“Gold-copper mineralization at Volcan is related to the intensely developed hydrothermal alteration that gave rise to the native sulphur deposits. The hydrothermal system was a consequence of the sub-volcanic intrusion of dacitic to microdioritic porphyry into a complex of domes and lava flows of dacitic composition.
[Mineral] occurrences are associated with [...] subvolcanic intrusive events [that] are responsible for the extensive and widespread [...] high sulphidation epithermal style alteration and mineralization.”
Compaction tests show a general amenability to percolation even when loaded.
Bond Work Index grindability tests resulted in a ball mill work index of 17.4 kWh/tonne (relatively high) at 100 mesh. Pre-feasibility tests indicate that tertiary crushing would be required to liberate the gold.
Anticipated Project Phases or Project Plan
Phase 0 – Proposed method review
- Propose or describe a method of gold extraction that meets the technical objectives of this RFP, providing supporting evidence or reason to believe the process may be feasible. Describe your assessment for potential success and any potential limitations. Hochschild will evaluate submissions and select all promising approaches for proof of concept engagement, to be negotiated as warranted.
Phase 1 – Proof of concept
- Demonstrate proposed process at lab scale. As needed, 10 kg ore samples from the Volcan mine will be made available to those offering a potentially promising path forward to test their process on the target ore body composition. Based on lab scale results, promising methods will be supported for scale up investigations. Site visit as warranted.
Phase 2 – Engineering co-development, under appropriate agreements negotiated between the parties. With the assistance of Hochschild technical staff,
- Assess economic feasibility of approach
- Optimize process parameters
- Develop a scalable pilot process for 2-3 tons/day
All proposals submitted in response to this Request for Proposal do not constitute an offer. Any proposals selected to move to each of the project phases will not be deemed as a Hochschild acceptance of such proposal nor an agreement (nor a commitment to enter into an agreement) with any solution provider. Hochschild’s only commitments under this RFP will exclusively derive from the execution of a definitive agreement between Hochschild and the solution provider.