Resources

The two kimberlite pipes (Main and Satellite) that form the resource are low diamond grade, high diamond value. This is unique for kimberlite deposits and is more characteristic of an alluvial deposit. All indicated resources have been converted to probable reserves (SAMREC).

Inferred resources, although significant, will not be converted due to the cost implications.

Total resources that will be mined by open pit method indicate a 33 year mine life. This is based on the present plant throughput of the indicated and inferred resources.

Production is characterised by regular production of large diamonds over 100 carats, including the Lesotho Promise which at a mass of 603ct is the fifteenth largest diamond mined in the world, the 601 ct Lesotho Brown ranked 16th in the world, the Letšeng Legacy at 494ct, Leseli la Letšeng at 478ct, the unnamed 196 ct D colour, internally flawless rough white diamond discovered in August 2010 and the 185ct rough white diamond recovered in October 2010.

Mining

Both the Satellite and Main Pipes are mined using conventional open-pit mining techniques. Drilling is done with Atlas Copco Rock L8 machines. Loading is done with Cat 385 Excavators, Waste Hauling with Cat773 Rigid Dup Trucks and ore Hauling with Cat 740 ADT. The production rate from 2008, after the addition of the second plant, to Letšeng treatment plants is budgeted at 5.7 million tonnes per annum. An additional 1.3 Million tonnes per annum is treated by Alluvial Ventures two pants plants through a contractual arrangement

The waste stripping rate has escalated to 16.8 million tonnes per annum.

Treatment

Production through No 1 Plant commenced in March 2004.

The first ore treated through No 2 plant took place on 23 March 2008. This plant was commissioned at full production at the end of the 2nd quarter 2008. The continued production from the two plants is budgeted at 460 000 tons per month.

To view the entire production cycle in a PowerPoint presentation please click here.

Recovery

Letšeng Recovery, as it implies, is a place to recover the diamonds and the final step in the production process.

The recovery section is made up of five floors incorporating:

• Floor 4 - Sizing screens, +2mm - +16mm (45mm being the planned cut off to enable the recovery of up to 1000ct stones).
• Floor 3 - The bin floor enables flexibility of concentrate feed where the concentrate is stored after screening before moving on to the Flow sorts.
• Floor 2 - The Flow Sort floor, 5 x wet x-ray units called Flow Sorts, that operate on a basic medical x-ray system but instead of looking for broken bones looks for luminescent material of which diamond is one.
• Floor 1 - The dryer floor where two IR dryers treat the finer size luminescent fraction (+2mm - -8mm) before sending it to the ground floor to the glove boxes for sorting.
• Ground floor - The hub of the operation where the diamonds are recovered from non diamond material, counted, weighed and prepared for export. The recovered diamonds are then stored in class 4 safes on time locks in the export room.

None of this would be possible without the hard working Recovery teams consisting of 3 to a team with a manager. The teams are on a two week shift system but on 24hr call out. Between the two teams there is over 66 years of experience in the diamond industry.

Ongoing evaluation of the diamonds is conducted in the recovery section. The final valuation is conducted in house before exporting to Belgium. Once valued the diamonds are exported to Belgium. When the diamonds arrive in Belgium they are boiled in high temperature hydrofluoric acid to remove any external kimberlite latching etc. Once cleaned the diamonds are revalued and split into sale lot before inviting companies to tender for the diamonds.

Letšeng's Diamonds are the highest valued diamonds in the world from the highest diamond mine in the world.

DIAMONDS IN THE SKY…..