Contracting

Thermal Fragmentation

This technology is not new, it has been used as far back as history can record.

In recent history it has been used in dimension stone and large-scale open pit operations for enlarging blast holes. Now this technology has been developed further, specifically for underground applications. This has been done and patented by a Canadian based Company, Rocmec Mining. maXem is licenced to use and introduce this technology into Southern Africa.

There is a clear need to develop new and more efficient mining methods in order to make mining safer and more profitable:

• by mining deeper

• by improving productivity

• by minimising ore dilution

The Thermal Fragmentation Mining Method has been developed to solve this particular challenge

Productivity

The team required to operate a Thermal Fragmentation unit consists of 3 people

• 2 drilling operators

• 1 thermal fragmentation operator

And, with Thermal Fragmentation, less rock needs to be mucked, and hauled from the stope. This results in even more downstream savings.

Thermal Fragmentation Mining Method

Thermal fragmentation is a continuous mining method that does not rely on explosives. Soft explosives can however be used to break out any vein or rock remaining between the thermal holes. This blasting activity can be managed much more effectively within the mining cycle.

A 6” pilot hole is drilled into the vein or rock using conventional long hole drilling techniques. A strong, diesel powered thermal lance is inserted into this pilot hole. The thermal lances creates heat energy which spalls the rock into small fragments. The hole can be spalled to any diameter, up to about 100 cm.

Selective Ore Extraction

A narrow vein of 30 cm to 100 cm can easily be extracted. The waste hanging and foot walls on either side of the ore are left intact without any blast damage. The Stope Hanging Wall conditions will be improved and will lead to a dramatic reduction in FOG risk, with access to the ore body never being compromised. In stope dilution and inefficiencies associated with traditional mining methods are enormously reduced.

Safety

•This Thermal Method has a proven safety record with no safety incidents recorded to date

•Multiple gas detection is used to ensure that equipment is stopped if hazardous gasses are encountered

•Thermal holes are flushed with compressed air before and during thermal fracturing

•Thermal holes are not confined so there is no danger of methane explosion in the hole

•Any methane encountered while operating is simply burnt off within the hole

•Diesel combustion is complete at high temperature (+-1800°C) so no CO is emitted

The Thermal Lance

The lance is powered by diesel fuel and compressed air and generates temperatures up to 1800°C in the combustion chamber. In the hole, a thermal cushion of hot air is formed which produces thermal stresses when coming in contact with the rock. A spalling effect occurs, and the rock is scaled off the hole walls and broken loose by the compressed air.

The Fragmented Rock

The process of fragmenting the rock is optimal in hard, dense rock. The spalling process produces rock fragments of 0 - 13 mm in size. In the case of vein mining, the finely fragmented ore can be more efficiently handled and transported, and requires no crushing before entering the mill.

Drop and Inverse Raising

Conventional Raising is associated with severe safety risks. Drop and Inverse Raising is therefore the preferred, but carries the risk of freezing a blast. In any blasting operation, if the cut is successfully removed, then the rest of the blast will come out successfully. A thermal cut can significantly reduce the risk of Drop and Inverse Raising.

Conclusion

Thermal Fragmentation is an innovative and effective new method for:

• Selective Narrow Vein Mining

• Safe and “Risk Free” Drop & Inverse Raising

It has been tested in South African and has shown that it is one of the most promising methods which provide significant advantages in a short space of time. Its new, not difficult!