Andean Precious Metals Corporation (APM) has confirmed the launch of an Expansion Study on its San Bartolomé mine, an important step in its strategic plan to prolong mine-life, which could include the production of tin.
The San Bartolomé project, situated in Potosi, Bolivia, is owned and operated by APM. Predominantly a silver mine, this project has produced an average of over five million ounces of silver per year since 2008.
The $2 million Expansion Study will be split into three parts: an updated Mineral Resource Estimate (MRE), a Scoping Study, and a Tailings Evaluation.
Over the 13 years of operations, fine material (<2.5mm) was screened out before it could be processed and was subsequently stockpiled in the mine’s Fines Disposal Facility (FDF). The FDF now contains some ten million tonnes of this material. Not only is some silver still present in the fines, but APM believes that this is a potential source of tin, having been mined from deposits in Cerro Rico that are known to carry significant tin grades.
Andean has already almost completed all the drilling required to produce an MRE for the FDF and aims to release the statement in January 2022.
The Scoping Study will evaluate the tin processing options of the stockpiled material. The choice between a gravity circuit upgrade to the current plant or a new stand-alone plant is dependent on optimum tin recovery. The testing of the physical properties of stockpiled material for this evaluation is ongoing and is set to be released Q1 2022.
A further opportunity for tin production is the dry stack tailings facility (DSF), which contains 18 million tonnes of material. These tailings have previously been processed for silver, but not for tin. Drilling has commenced on the tailings to evaluate the quantity and grades of tin but will not be included in the updated MRE. APM expect to release results from this drilling campaign in Q1 2022 separately.
Our view: APM’s San Bartolomé project represents a near-market opportunity for tin production based on the low CAPEX, low development nature of similar greyfield projects. In a previous Investor Presentation, the tailings alone were estimated to contains some 10 million tonnes of material at 0.25% Sn (25,000 tonnes tin). Having already been crushed, APM believes that both stockpiles (the FDF and DSF) could be amenable to low-cost hydraulic mining methods.