Prodigy Gold testing confirms SAG milling option at Magino

Mon 9:23 am by Deborah Sterescu

Prodigy Gold (CVE:PDG) announced Monday that testing has confirmed an SAG milling option at its Magino gold mine in northern Ontario, which typically has lower operating costs than similar-sized all-ball milling circuits.

SAG is an acronym for semi-autogenous grinding, and these mills are essentially autogenous mills, but use grinding balls to aid in grinding like in a ball mill. An SAG mill, which is characterized by its large diameter and short length as compared to ball mills, is generally used as a primary or first stage grinding solution, and uses a minimal ball charge.

The company released Monday the results of SAG design test work and SAG design comminution analysis conducted by Starkey and Associates on representative samples of gold mineralized rock from Prodigy's Magino mine.

The results were used to predict grinding equipment and energy requirements for the proposed mill at Magino.
Four samples of unsplit core totaling 121.6 kilograms showed hard competency for SAG milling and moderate-to-hard competency for ball mill grindability with an average Bond Work Index (BWI) of 14.81, Prodigy said.

Using a design BWI of 15.81, Starkey recommended a conventional single line grinding circuit with one SAG mill followed by two ball mills in parallel, with total throughput of 17,500 tonnes per day at the project, which can be expanded to 20,000 tonnes per day with the addition of a single cone crusher, the company said.

"Verifying the SAG milling option is important to the economic analysis of the Magino mine project as SAG milling circuits typically have lower unit operating costs than similar sized all-ball milling circuits," Prodigy explained in a statement.

The grindability data will be incorporated into an updated Magino mine preliminary economic assessment (PEA), expected later this year.

The company is currently evaluating the development of the Magino mine gold project as an open-pit mining opportunity with the potential for deeper, higher grade gold production.

Announced last week, the property now contains indicated gold resources of 2.18 million ounces grading 1.00 grams per tonne (g/t) gold, and 1.72 million ounces of inferred gold resources grading 0.99 g/t gold, at a cut off grade of 0.35 gpt gold.

A preliminary economic report based on the older February resource estimate showed a pre-tax net present value of $351million and an internal rate of return of 49 percent, using a five percent discount rate. The proposed operation would have an average annual gold output of over 166,000 ounces a year during a nine year project life. Total gold production is estimated to be 1.50 million ounces at cash costs of approximately US$496 (C$521) per ounce.

The upcoming PEA will also include the results of the latest resource estimate released last week. A full feasibility study for the proposed open pit mining project at Magino is due out in mid 2012.