The Argyle diamond deposit, located in the AK1 pipe was mined using conventional alluvial and open pit mining from 1983 to 2013. Over this period of time more than 800 million carats of diamonds were mined. In 2013 a new era of underground mining of the AK1 pit took over to access the pipe at further depth.
Block cave mining techniques – where the ore body is undercut, allowing it to break up and ‘cave’ under its own weight – are now being employed to extend the life of the Argyle mine until at least 2020. The block cave is expected to generate on average 20 million carats per year.
The decision to construct a block cave mine followed extensive studies into the safest and most economic way to reach deep into Argyle’s ore body. The technologically advanced underground operation is the first of its type in Western Australia and one of only a handful in Australia.
The Argyle underground mine is a challenge both in size and complexity. There are around 40 kilometers of tunnels. The main thoroughfares in the underground network are four tunnels – two to carry vehicles, one for ventilation and one for moving ore. There are two large underground crushers and conveyor belts transport the ore from deep in the mine to the surface.
When Argyle was first established, it became apparent that purpose-designed processing machinery would be needed to recover and sort the high volume of characteristically small stones produced by the mine. This included the development of sophisticated X-ray sorting technology to assist in the efficient identification and collection of the small diamonds.
Today, the Argyle processing plant is one of the most efficient in the world. It is capable of processing up to 11 million tonnes of ore per annum.
The Argyle mine and processing plant operate 24 hours a day, 365 days of the year.