Blaauwbosch Processing Operations

The Blaauwbosch mine is located about 90 kilometres east of Kimberley, in the well-known diamond-producing area of Boshoff. Blaauwbosch was originally mined to a depth of 110 metres and produced an estimated 967,000 tonnes of ore, yielding some 338,000 carats at an average grade of 34.95 carats per hundred tonnes ('cpht'). This operating mine is currently undergoing an expansion. The planned output is 14,000 tonnes per month ('tpm') at a grade of 30 carats per hundred tonnes ('cpht') and sales revenues of $110 per carat.

Headgear at Blaauwbosch

The Blaauwbosch resource comprises two kimberlite pipes ('Main Pipe' and 'Vulcan Blow') with connecting fissures. In addition, a number of sub-parallel kimberlite bearing fissures and the Vulcan Blow remain untested.

Since its purchase by Dwyka in 2005, the main shaft has been sunk from a depth of 145 to 225 metres, with a horizontal haulage level developed at a depth of 205 metres. A second access and ventilation shaft has been sunk to 145 metres, with upper-level development for long-hole stoping now complete.

As part of the on-going development programme, KimCor, is completing capital projects that will increase underground production rates by introducing a sub-level caving mining method in the main pipe, with a complementary scraper winch system to remove ore from the mining faces. The fissures associated with the main pipe are being developed downwards from the 145m level and the smaller second kimberlite pipe from the 225m level.

The capital programme being implemented by KimCor will result in the following:

• Increasing processing plant capacity. Underground development has provided access to additional working faces and opened up the main ore body. With the introduction of a new scraper winch system, the mine is capable of hoisting between 10 and 15,000tpm;
• The current processing plant can treat only 6,000tpm. The existing plant is to be reconfigured with extra diamond recovery pan capacity;
• Improvements in diamond recovery. Presently, the plant can only reduce ore fragments to -20mm with the likely result that diamonds remain locked up in kimberlite. Reduction of the ore sizes reporting to the pan plant is expected to improve recoveries by liberating diamonds currently remaining locked in kimberlite fragments;
• Increasing underground production to approximately 160,000 tonnes per annum ('tpa') generating up to 48,000 carats based on an estimated recoverable grade of 30cpht;
• Lowering of operating costs in line with increased underground production and plant throughput.