ASX-listed metals producer Alcyone Resources is increasing silver production at its 100% owned Texas silver and polymetallic project in south-east Queensland to a targeted rate of 1.5-million ounces to 2-million ounces a year, following progress in the wet commissioning of the upgraded Twin Hills processing facility.

The crushing facility is operating with 100% of materials greater than 4 mm, which is one of the key parameters to achieving the design leach rates. Wet commissioning of the upgraded crushing circuit and heap leach processing facility started on August 12, and the plant is already operating at close to its nameplate capacity of 150 t/h, which equates to a yearly throughput rate of one-million tons a year.

Alcyone Resources MD Andrew King said that he was encouraged by the progress that has already been made with the commissioning work, which lays the foundation for the transition to commercial silver production at the Texas project.

“The plant is performing beyond our expectations for this stage of commissioning. When coupled with the production of over 210 000 oz of silver to date, this represents another key milestone towards achieving full-scale commercial silver production,” reports King.

The quad rolls crusher has been commissioned and is now ramping up to peak throughput rates of over 140 t/h, with an overall average of 80% of the 150 t/h design rate achieved to date.

The crusher is currently attaining a steady state of 140 t/h and delivering a product size of 100% passing 3.8 mm, which marginally exceeds the design criteria of 100% larger than 4 mm.

Further, the commercial-scale Merrill Crowe circuit, which is used to extract the silver from solution, replaced the pilot scale plant on August 24. The circuit is currently running at nameplate capacity of 200 m2/h, resulting in a significant boost to bullion production. The automation package is expected to further enhance overall process productivity and the overall silver recovery circuit is currently achieving recoveries from solution of more than 96%, compared with the targeted level of 95%, based on previous testwork.

“There could not be a better time to start a silver mine, with silver prices continuing to strengthen and providing us with an exceptional cash operating margin. With our life-of-mine unit operating costs forecast at A$5/oz, this equates to a cash operating margin at the current spot price of around A$26/oz, which is a very healthy proposition for a company entering a production ramp-up phase,” he says.

“We are looking forward to the next milestone, which includes the start of mining and the ramp-up to full commercial production at a yearly production rate of 1.5- million ounces a year to 2-million ounces a year by the end of this year,” King added.

In addition, installation of the new bullion circuit was completed in July, with the circuit commissioned and producing silver bullion on site. The bullion circuit has a yearly production capacity of two-million ounces.

Initial silver production has been based on reirrigating the existing silver-rich heaps, which have been estimated to contain about 250 000 oz of recoverable silver.

Further, the company-owned rotary air blast rig is currently drilling the prospective silver and base metal corridor, while the contract reverse circulation rig is undertaking the first phase of grade control drilling. It will then target further mineralisation extensions along the strike and downdip.

The heaps continue to leach the silver at a steady rate and, with over 210 000 oz of bullion already produced since trial processing started in April, the company is on its way to achieving its original 250 000 oz production target from this source. The second 100 000 oz of silver production was achieved in five weeks and reflects both the improved heap dynamics, as well the commissioning of the new Merrill Crowe circuit.

This early production has enabled the company to take advantage of strong silver prices and generate significant early cash flow.

Alcyone has over 200 000 t of medium-grade to low-grade ore on the run-of-mine stockpile that is being used for the initial wet commissioning of the plant, with a further 180 000 t of higher- grade ore already exposed within the opencut, ready for extraction.

Laboratory testing of the product being stockpiled has indi- cated that the leaching rates should achieve the forecast leaching rates as defined in the original testwork, and irrigation of the newly stockpiled material has started, in order to provide percolation results.

Owing to the progress of the plant commissioning, Alcyone started mining in the Twin Hills openpit in late September, which will provide a regular ore feed to the plant, and enable the company to increase production to the targeted yearly rate of 1.5-million ounces a year to 2-million ounces a year by year end.