Reserves triple at Cambior’s Granja deposit

Proven and probable reserves at Peru’s La Granja copper project have increased, following completion of a 100-hole, 36,000-metre drill program.

In March, 1994, when Cambior (TSE) signed an option to acquire the project, probable and possible reserves stood at 175 million tonnes averaging 0.84% copper at a cutoff grade of 0.5%.

They have since tripled, rising to 596 million tonnes grading 0.73% copper in the proven and probable categories.

La Granja is 650 km north of Lima on the eastern flank of the Andes at an elevation of 2,000-2,700 metres above sea level. Two zones are hosted within a highly altered, late Tertiary-aged intrusive. The deposit remains open laterally and at depth.

To acquire the property, Cambior must spend US$25 million on exploration and development over a 5-year period, as well as prepare a feasibility study. To date, Cambior has spent US$14 million on the project, including a second option payment of US$2 million and expenditures of US$6 million for the first six months of 1995.

In the next 6 months, the company will drill an additional 14,000 metres to delineate the deposit. The work will be completed on 200-metre centres, with infill drilling used in certain areas on 100-metre centres. The prefeasibity study is expected by early 1996.

Ongoing metallurgical tests confirm that flotation recoveries of copper are about 90% and that copper concentrates of 30-32% can be produced. In addition, a preliminary mine plan suggests that 70 million tonnes grading 1% copper could be mined in the first five years, with a waste-to-ore ratio of 1.31:1. At this rate, average annual production is anticipated to be 375 million lb. copper.

Once the prefeasibility study is completed, Cambior will initiate a full feasibility. Construction is expected to begin in 1997, and commercial production by 1999.