TSX-V-listed silver, gold and copper explorer and developer Silver Bullet Mines (SBMI) is progressing with the construction of a 125 t/d modular pilot plant in Arizona, in the US, and is on track to start commissioning of the plant in the first quarter of this year.
Currently, over 90% of the necessary equipment is on site and being assembled, while the remainder is in a container in Long Beach, California, waiting to be off-loaded, on a timeline beyond the company’s control.
In addition, some small items are still to be bought, as required.
The plant is designed to increase the recovery of both gold and silver, although its modular nature means it can be adjusted to recover other metals.
Because of its modular design, the plant’s size may also be expanded should the need arise.
The plant is being built on SBMI-owned private property about 12.8 km from Globe, Arizona, and is near its Buckeye silver mine.
SBMI CEO John Carter says that, despite ongoing supply chain issues and exorbitant material and transportation cost increases, the company remains on track to start commissioning before the end of March.
“In anticipation of that commissioning, [SBMI] has about 1 000 t of material already stockpiled for feed.”
The plant comprises a coarse ore feed bin, a fine ore bin, two-stage crushing and screening and a variable speed computer-controlled feed belt that leads to a grinding circuit. The grinding circuit is a ball mill in closed-circuit with a bank of cyclones.
The plan is for product from the ball mill to be pumped directly to a pair of Falcon concentrators. The product from the concentrators is then fed by gravity to a full-size Diester concentrating table.
Tailings from the concentrators and from the table are returned to the grinding circuit.
After this, the cyclones then split the feed with the oversize material going back to the ball mill, while the undersize material goes to the tailings thickener.
Processed material of the appropriate size is then sent to the bullion furnace where dore bars are poured. SBMI notes that it is in discussions with various groups concerning the purchase of both the dore and the concentrates.
All tailings are dewatered and all available water is recycled.
In addition to owning its own processing plant, SBMI owns an on-site assay facility which can provide assay results in less than a day.
The company also owns its own two-boom jumbo load-haul-dumper, a large skid steer and various other equipment.
Owning all this equipment enables SBMI to process feed material quickly, efficiently and economically, as well as to generate revenue, without debt payments draining cash.
Meanwhile, SBMI reports that it does not intend to spend capital on a third-party resource estimate or preliminary economic analysis (PEA) for the Buckeye silver mine because the company regards a PEA as being “prohibitively expensive” to have written without actually advancing its knowledge of Buckeye.
In addition to this, SBMI says the nature of the known mineralisation, the extensive historical third-party documentation and the leadership team's direct experience at Buckeye also drove the decision to not conduct a third-party resource estimate or PEA.
“This is old school mining, and for this project, it is the right way,” says Carter.
He adds that producing from 1.8-m-wide silver veins is not a standard mining opportunity, which means it requires a non-standard approach. “Here, we believe the right approach is to carry out our own internal economic analysis.”
The next major events at Buckeye will be the arrival on-site of the third container through the Long Beach supply chain, and the delivery of assay results from a third-party-accredited lab on one-quarter of a 68 kg bulk sample.
However, SBMI notes that it has no direct control over the timing of either of those events, but will continue to work with its suppliers to expedite them as much as is possible.