Mass mining including block caving, incline caving, front caving, sub-level caving and sub-level retreat are the principal mining methods for primary diamond deposits worldwide. Diamonds have only been mined on an industrial scale within the past 150 years, mainly as open pit mines. Underground mining of those deposits was first implemented within the second half of the 20th century in South Africa. A relatively large number of underground mining methods were tested, implemented, and evolved over the past 50 years, mainly in South African mines. In the mid-1990s, Alrosa, a Russian group of diamond mining companies, started developing the first underground diamond mine in Russia, Internationalnaya. Since then, Alrosa continued to implement underground mining on several of their mines, including Aikhal, Mir and Udachny. China also experimented with underground mining at Nhangma 701 Diamond Mine at the end of the 1990s, but the largest development of diamond underground mining took place in Canada. Today, out of some 40 diamond mines mining kimberlite, approximately half are underground and another 20 have underground plans or they are exploring its potential.
SRK has been involved in most of the underground diamond mining projects around the world. In Canada, the Ekati Diamond Mine was the first diamond mine to be developed near Lac de Gras in Canada’s Northwest Territories. Koala North Pipe has been developed and mined as an open-benching, mechanised, and trackless operation to test the underground mining method and to provide access to the lower parts of the Panda and Koala pipes which were developed and mined underground once the open pit operations were completed. Koala North, North America’s first underground diamond mine, formally opened in 2002. Since then, Panda and Koala Pipes were mined by three principal underground mining methods: sub-level retreat, sub-level caving and Incline Caving.
Diavik Diamond Mine started open pit production in 2003. By 2005, underground development had commenced with plans to mine the A154 and A418 pipes using backfill methods. As geotechnical knowledge was gained, the mining methods were re-evaluated. The sub-level retreat method was chosen for the A154S and A418 pipes, and blasthole open stoping with cemented rockfill was chosen for the A154N pipe. In 2012, the open pits reached their ultimate depths and Diavik Diamond Mine became a fully underground operation. In 2018, open pit mining of A21 kimberlite was successfully commissioned, complementing underground mining at Diavik.
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