EXPLORATION 1997 — Nord adds to copper resource at its Tritton deposit

In the flatlands of New South Wales, Nord Pacific (NORPY-Q) continues to hit high-grade copper mineralization at the Tritton massive sulphide deposit, a 50-50 joint venture with Australian-listed Straits Resources.

On a recent swing through the area, The Northern Miner noted that drilling is concentrating on following extensions of the Tritton mineralization at depth.

The deposit plunges from a depth of 150 metres below the surface to deeper than 1,000 metres, and averages 300 metres in width. The company first intercepted high-grade copper values at Tritton in 1995 while testing ground geophysical anomalies.

Recent drilling was highlighted by 14 metres grading 3.4% copper from a depth of 885 metres. Other holes hit: 10 metres of massive sulphides grading 3.4% copper from 959 metres; 16 metres grading 3.8% copper from 894 metres; and 14 metres of 4.3% copper from 532 metres.

The upper zone contains the higher-grade material, with values ranging from 4% to 5% copper, while the lower zone contains the bulk of the tonnage. The joint venture has calculated a resource of about 9.7 million tonnes grading 3% copper, plus 0.21 gram gold and 11 grams silver per tonne (using a 1% copper cutoff).

The joint venture is preparing a final feasibility on the Tritton, to be completed this year. Nord President Pierce Carson said the company hopes to amass sufficient data to warrant underground development. Permitting is expected to begin after the feasibility is completed, with startup projected for early 1999.

The joint venture is evaluating processing alternatives, including several innovative low-temperature/low-pressure methods. The material will be put through a flotation circuit, with concentrates sent either to a smelter or to a processor on site.

“There are certain economic advantages to processing on site,” Carson told The Northern Miner. The material would be sent through fine grinding, and then to low temperature/low pressure oxidation, with copper cathode produced by means of solvent extraction-electrowinning (SX-EW).

Preliminary estimates call for a 2-year payback on investment, and it is estimated the Tritton deposit could support a mine life of 10 years.

The deposit is 20 km southwest of the Girilambone copper mine, which is a 60-40 joint venture between Straits and Nord Pacific, respectively.

The joint venture owns 3,200 sq. km in the Girilambone area, which contains several exploration targets. Among these is the Budgerygar prospect, which contains an estimated 15,000 tonnes of low-grade mineralization at a depth of less than 100 metres.

Over the next year, the joint venture will spend A$4.6 million on further geophysical surveys and drilling of targets.

Production

Nord Pacific has a 40% share in copper production from the Girilambone mine, which yielded 35.9 million lb. in 1996, an increase of 27% over the previous year.

The increase is attributed to a program that resulted in aeration of the heap-leach pads. Mark Welch, Nord Pacific’s vice-president of operations, said the aeration led to faster leaching cycles and enabled the mine to reach its goal of 85% recovery.

Cash costs for the year dropped to 37 cents per lb. in the fourth quarter (31% lower than in the previous 3-month period) and are expected to remain in that range during 1997.

Girilambone was among the first users of SX-EW in Australia, and was the first mine in the world to apply heap leaching to material that features chalcocite as a primary ore.

The mine was opened in 1993 and is expected to last six more years, owing chiefly to the addition of reserves from the Girilambone North project.

Carson said three years’ worth of production await heap-leaching.