Overview
The Cannington Silver Mine located in Quennsland Australia produces more silver and lead at lower cost than any other mine in the world. Owned by the mammoth public company, BHP Billiton, it employs close to 1,000 miners, staff and independent contractors.
History
In 1990, BHP Minerals was awed and more than a little elated by the massive find at Cannington. A$450 million and seven years later, the mine was opened and full production began in 1999. Capacity has steadily increased. Currently, on an annualized basis, three million metric tonnes of ore are processed yielding 750 tonnes of silver and 265 thousand tonnes of lead. In addition, substantial amounts of zinc are recovered.
Processing Methods
Currently, the Cannington mine produces six percent of the world’s silver and seven percent of its lead. To achieve these results, the ore is processed in a variety of ways. The first step is comminution, the simple mechanical crushing and grinding of the ore. The resulting material is then subjected to a variety of mechanical and chemical processes that concentrate the metals based on their physical properties. These properties range from density, particle size and shape, through electrical and magnetic properties, to surface properties.
Ultimately, the silver is leached from the zinc and lead streams in a separate chemical process. The separate metals are then smelted and stored for transportation. At Cannington, demand is so great that BHP Billiton maintains a railhead nearby for the storage and subsequent shipment of the refined metals.
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