OZ Minerals Limited operates a silver-lead-zinc mine at Rosebery on Tasmania's west coast. The history of mining in this area dates back to 1893, when the first discovery of mineralisation was made in a creek on the slopes of Mt Black. The Electrolytic Zinc Company of Australasia Limited purchased the Rosebery mines in 1920 and operated them until EZ was taken over North Broken Hill Peko Limited in 1984, with Pasminco Mining being formed in 1988 and Zinifex in 2004. The mine became part of the OZ Minerals group in 2008.
The sulphide ores at Rosebery are mined underground and taken to surface crushers and concentrators for treatment. A new decline was opened in 2003 to replace the former shaft hoisting system.
Ore production from the Rosebery mine was 739 900 tonnes in 2007/2008. A total of 726 800 tonnes of ore from Rosebery and 34 700 tonnes from Que River was treated at a head grade of 11.43% Zn, 3.65% Pb, 0.34% Cu, 136 g/t Ag and 1.63 g/t Au.
Concentrate production comprised:
- Zinc concentrate - 142 900 tonnes at 54.52% Zn;
- Lead concentrate - 34 000 tonnes at 63.64% Pb, 1262 g/t Ag;
- Copper concentrate - 7 380 tonnes at 19.3% Cu, 8.72% Pb, 5026 g/t Ag and 49.3 g/t Au;
- Dore - 499 kg containing 35.8% Ag and 60.26% Au.
The concentrates are rail-hauled to Burnie for shipment to processors.
The total proved and probable ore reserve at March 2007 was 4.96 million tonnes at 2.9% Pb, 10.1% Zn, 0.3% Cu, 102 g/t Ag and 1.4 g/t Au.
Employment at 30 June 2008 was approximately 196.
