Nevsun Resources has completed construction of the new zinc concentrator at its Bisha operations in Eritrea and began commissioning the plant in early June. The company has previously produced copper concentrates from the Bisha deposit’s copper-enriched supergene zone, which overlies a primary sulphide zone containing both zinc and copper. The new zinc flotation plant adds to existing copper flotation, and Nevsun now expects to produce both zinc and copper concentrates throughout Bisha’s currently planned nine-year mine life.
Bisha is mined using conventional drill-and-blast, open-pit techniques to remove waste and deliver ore to the run-of-mine stockpile. The copper and zinc flotation plants are both conventional circuits with rougher, cleaner, and IsaMill regrind. Copper and zinc concentrates are thickened, dewatered, and stockpiled prior to road-haulage transport to the port of Massawa for shipment to world markets.
The new zinc plant was completed coincident with the exhaustion of the supergene ore. Nevsun estimates that the cost of the project will come in at less than $80 million, against a budget of $100 million.
Workers install electrical components during the final stages of construction at Nevsun’s zinc concentrator, which was recently completed under budget at an estimated cost of $80 million. (Photo: Nevsun Resources)
Bisha production is now forecast to average more than 100,000 metric tons per year (mt/y) of zinc and 20,000 mt/y of copper in concentrates, and the plants have excess capacity to absorb additional feed that might come from deposits currently.
As the tonnages of copper and zinc concentrates produced going forward will be similar to copper concentrate tonnages produced in the past, there has been no need for additional transport or shipping infrastructure upgrades.
Bisha is based on a large, high-grade volcanogenic massive sulphide deposit 150 km west of Asmara, Eritrea. The Bisha Main deposit is located within the Bisha mining license, and the Harena satellite deposit occurs in a separate mining license 6 km to the south. Bisha Main and Harena currently account for 100% of the mineral reserves at Bisha.
The state of Eritrea has a 40% interest in the Bisha operations through the Eritrean National Mining Co.