Adex makes gains at Mount Pleasant

The financing necessary to put New Brunswick’s Mount Pleasant polymetallic mine back into production may be forthcoming, Adex Mining (TSE) reports.

Discussions include both equity and debt arrangements for a total consideration of $35-40 million. Adex management is considering several proposals and potential combinations. Depending on the outcome of negotiations, management has stated that a production decision to operate the Mount Pleasant mine at 2,000 tonnes per day for 10 years could be made soon.

The North zone, on which the company’s positive prefeasibility study was based, contains proven and probable reserves of 7.1 million tonnes grading 0.62% tin, 0.65% zinc, as well as 91 grams indium per tonne and some copper, bismuth, molybdenum and tungsten values.

In addition, the Fire Tower zone has proven reserves of 9 million tonnes of 0.03% tin, 0.08% zinc, 0.2% MoS2 and 0.4% WO3 plus 31 grams indium per tonne. Several other zones contain a possible reserve total of more than 29 million tonnes.

In 1995, Adex began a program of entering all existing mine and exploration information in a computer mine modelling program. Using this database and the results of Adex’s 1995 drill program, the company estimated that the newly identified Scotia zone has possible reserves of 1 million tonnes grading 0.42% tin, 3.26% zinc, 0.67% copper and 2.7 oz. indium per ton. These reserves are open in all lateral directions and lie within 25 metres of an existing underground development drift.

Since October 1995, Adex has been carrying out a series of bio-oxidation pilot plant programs using sulphide materials from the Mount Pleasant site. The success of a bio-leach process, which recovers indium from a sulphide concentrate produced after tin flotation, is considered critical to the redevelopment of the mine. Adex reports that preliminary results have been encouraging, with the indium recovery rate exceeding 80%.

A final independent prefeasibility study detailing the bio-leach process is expected in early April.

Demand for indium has increased, as a result of its use in thin film transmission technologies, such as liquid-crystal-display portable computers.

Annual production from Mount Pleasant is projected at 800,000 oz. Indium currently sells for about US$15 per oz.

With the recent European decision to produce steel-tin beverage cans to compete with the aluminum can market there, the demand for tin is also increasing. Annual production from Mount Pleasant is projected at 7-8 million lb. Tin prices are currently in the range of US$3 per lb.

The mine produced tungsten, molybdenum and several other metals between 1983 and 1985, before it was shut down as a result of low metal recoveries.