Nippon Dragon Resources has revealed more details about testing of its exclusive and patented thermal fragmentation technology in South Africa following a recent presentation from AngloGold Ashanti.

The company’s South Africa distributor, MaXem, who attended the open-day presentation organised by the Mandela Mining Precinct, provided the details, Nippon said.

Nippon’s thermal fragmentation process for narrow vein mining involves drilling a series of 6 in (15 cm) pilot holes into the vein with a conventional drill. Thermal fragmentation (thermal head, compressed air and water) is then inserted and spalls the rock, quickly increasing the diameter of the hole to 30-110 cm. After this, ore can be extracted in 0-13 mm fragments. The leftover rock between fragmented holes is then broken to recover the remaining ore.

This precision allows for the extraction of high-grade precious and base metal veins without dilution, according to Nippon.

AngloGold Ashanti, which is a MaXem client, said over 200 holes were drilled and fragmented using the thermal fragmentation technology at one of its underground operations in South Africa. Of these holes, several exceeded 30 m in length.

One of the objectives of the test work was to drill, fragment, clean and backfill a hole within a 25-hour period; an objective the company achieved, Nippon said, adding that over the 200 holes completed, productivity ranged from between 3-6 t/h.

Two other projects are currently under review by the Non-Explosive Rock Breaking Programme within the Mandela Mining Precinct, MaXem and other partners, according to Nippon. One of these is the spallability classification of different rock types and the other is the employability of the thermal fragmentation technology within the platinum sector.

The Mandela Mining Precinct is established as a public and private partnership between the South African Government, the mining companies, manufacturers of mining equipment, research organisations and academia to foster collaboration and innovation. It “assists the mining industry in bringing change to processes, technologies, skillsets and social and environmental impacts associated with current mining through the modernisation of mines via mechanisation and automation”, Nippon says.