Dias Bras Looks to Build Mill at Bolivar

Dia Bras Exploration (DIB-V, DBEXF-O) has been pilot mining at the Bolivar copper-zinc mine in Chihuahua, Mexico, for nearly two years, but now that the company has completed a National Instrument 43-101 resource estimate, it can finally start a prefeasibility study for an on-site mill.

The Bolivar deposit is located 150 km southwest of the Malpaso mill, where ore is mined at a rate of 350 tonnes per day. Since 2005, Dia Bras has processed more than 190,000 tonnes of ore at the mill. The ore is currently shipped from the remote location in the Sierra Madre mountain range by road and rail.

“With a mill on-site, we will have a significant reduction in our production costs, thereby lowering the cutoff grades used in the evaluation with a resultant increase in tonnage,” said Thomas Robyn, executive chair, in a statement.

The resource so far is based on 306 diamond-drill holes from surface and underground for a total of 68,000 metres, with a cutoff grade of 2.5% copper equivalent. The cutoff was based on copper at US$2 per lb., zinc at US$1 per lb., silver at US$10 per lb. and gold at US$500 per lb.

Measured and indicated resources from the upper skarn deposit of Bolivar total 322,400 tonnes grading 1.82% copper, 6% zinc, 0.25 gram gold per tonne, 40 grams silver, and 6.44% iron (5.16% copper equivalent).

Inferred resources total 274,600 tonnes averaging 2.04% copper, 6.36% zinc, 0.35 gram gold per tonne, 50.5 grams silver, and 6.73% iron (5.67% copper equivalent).

The resources have an overall recovery rate of 80% for copper and 90% for zinc.

The upper skarn has high-grade copper-zinc manto-pipe-breccia mineralization while the lower skarn has lower-grade copper-magnetite replacement mineralization.

Dia Bras has also compiled a resource for the lower skarn deposit at Bolivar, which has only been drilled within an area that encompasses less than 5% of the known extent of the lower skarn horizon.

Using a 1.5% copper-equivalent cutoff, the inferred resource for the lower skarn is 936,000 tonnes grading 1.57% copper, 0.17% zinc, 0.45 gram gold per tonne, 29.3 grams silver, and 19.22% iron (1.99% copper equivalent).

If Dia Bras can confirm the inferred resource, the company projects it could feed the mill for five years at the current processing rate, while additional resources may be discovered and developed.