Minera completes optimization study at Bellavista

Minera Rayrock (TSE) has completed an “optimization” study on its Bellavista gold mine project in Costa Rica.

The study involved re-evaluating the reserve potential and revising the production schedule to reflect recovery variations and higher grades found at the deposit’s top.

The project, 112 km northwest of San Jose, was shut down in 1990 because the then-current gold price of US$330 per oz. rendered mining uneconomic. The original evaluation study was for a 4,000-tonne-per-day operation, with capital costs estimated at US$50 million and operating costs at US$230-250 per oz. A gold price of US$400 per oz. was required in 1990. The recent study, however, suggests there is potential to increase both reserves and grade. A final feasibility study, to be completed next year, is estimated to cost US$1.8 million and will include infill drilling. It is hoped the drilling will increase proven and probable reserves to 900,000 from 731,000 oz. The mine life would be extended to 12 years, and production would be 80,000 oz. for the first three years and 60,000 oz. per year thereafter.

In other developments, parent company Rayrock Yellowknife Resources (TSE) has obtained a US$18-million bank loan which Minera will use to develop its Ivan copper project in northern Chile. Production is expected to start in the third quarter of 1994 at 22 million lb. copper cathode per year. Cost: US55-60 cents per lb.

Exploration continues on several other Minera properties. Ground acquisition and reconnaissance work are progressing in the Farellon area, 250 km north of Santiago, Chile. The potential for large-tonnage, low-grade, open-pit gold deposits is being investigated there, with drill targets scheduled to be tested in early 1994.

Field work started last month on the Vaquillas project where the company will test for both gold and gold-copper porphyry targets. Minera is also exploring its wholly-owned Sierra Valenzuela copper property, 40 km northeast of Ivan. Reserve potential is 10-15 million tonnes grading 1.75% copper.