Noranda grabs Lady Loretta

Results from a 2-year study have prompted Noranda (NOR-T) to acquire a majority stake in the Lady Loretta zinc-lead-silver desposit in Queensland, Australia.

In 1998, Noranda signed a deal with Australian-listed Buka Minerals to acquire a 75% interest in the project for A$21 million. As part of the agreement, the major has spent more than A$3 million on exploration and purchased 3 million shares, at A50 apiece, in private placements.

Situated 140 km northwest of Mount Isa, the Lady Loretta prospect was discovered in the late 1960s, only to become a full-fledged deposit two decades later. Resources at the time were pegged at 8.3 million tonnes averaging 18.3% zinc, 8.3% lead and 125 grams silver per tonne.

Since acquiring its option, Noranda has sunk 34,943 metres in the area to block out substantially more tonnes. Resources now stand at 13.6 million tonnes grading 17.1% zinc, 5.9% lead and 97 grams silver.

Noranda has also increased recoveries (to 84% from 74%) and concentrate grades using conventional flotation techniques. In its attempt to overcome the deposit’s fine and complex mineralogy, Buka had tinkered with a proprietary fuming process before funding problems forced it to adopt a more conventional approach with Noranda.

Meanwhile, Buka continues a prefeasibility study of the nearby Lady Annie copper deposit. Noranda’s original option included that deposit, but the major backed away after sinking 17 holes and carrying out metallurgical tests on them.

Lady Annie, which lies 2.5 km southwest of Lady Loretta, hosts 5.6 million tonnes averaging 1.9% copper. A satellite deposit contains another 746,000 tonnes with an average copper grade of 2.8%.

Buka had hoped to share infrastructure costs between the two deposits. The current study is assessing the viability of a stand-alone, heap-leach operation.