Thermal Fragmentation Mining Method
Overview
Using a burner powered by diesel fuel, the intense heat created within the vein shatters the rock
containing the precious metal contents, into small fragments. The ore bearing vein is directly extracted,
greatly reducing the dilution factor and the inefficiencies associated with traditional mining methods
which extract large amounts of waste rock. With this method, it's now possible to extract a narrow
mining corridor with widths of 30 cm to 1 metre.
- 3 to 6 inch pilot holes drilled into the vein with conventional drill
- Thermal Fragmentation (burner operating at 1800 ° C) is inserted and spalls the rock, quickly increasing the diameter of the hole to 30 - 90 cm
- Extraction of ore in 0 - 13 mm fragments
- Break leftover rock between fragmented holes to recover remaining ore
Thermal Fragmentation Method in Greater Detail
Until recently, the use of chemical explosives was the only effective way of breaking hard rock. An
innovative approach, consisting in thermal fragmentation, is currently in operation. The technology
utilizes the heat generated by a powerful burner, powered by diesel fuel and air, to create a thermal
stress and break the rock. The thermal reaction allows for the enlargement of 15cm to 90cm holes by
breaking the rock in a spalling effect. This technology has been used in Russia for over 40 years in
large-scale open pits for the drilling of large blast holes. Use of this technology in selective ore
extraction is a definitive plus for gold properties that would otherwise be uneconomical using existing
mining methods.
The new approach to thermal fragmentation consists in the enlargement of a 15-cm hole previously
drilled with a long hole drill. A strong burner, powered by diesel fuel and air, is inserted in the hole,
lowered to the bottom and lighted. The heat generated raises the in-hole temperature up to 1800°C.
This creates thermal stresses that spall the rock. In simple terms, spalling is considered as a form of
decrepitation caused by an unequal expansion of rock crystals that overcomes molecule cohesion. The
broken material produced during this process ranges in size from fine-grained to 4 cm. A portion of the
material is ejected out of the hole as burning progresses and the rest can either be blown out of the hole
by compressed air or aspirated.
Each work site is organised within two superimposed drift levels, approximately 20 meters apart. By drifting directly into the ore, we minimise mining waste and development costs. Once, the fragmentation complete, the leftover rock between the fragmented holes is then blasted and remaining ore recovered. Through the use of soft explosive charges, the hangingwall and footwall are left intact and only the mineralised corridor itself is extracted.
