All of the subject Properties lie within the Orapa kimberlite cluster on the southwestern edge of the Zimbabwe Craton of Southern Africa with a stable, cool cratonic setting favourable for the intrusion of diamondiferous kimberlite and associated alluvial deposits. The Orapa cluster, comprising approximately 60 known pipes and dykes is located in north-eastern Botswana, east of the Kalahari sub-basin. During the late-Cretaceous epoch (~93 Ma), the Orapa kimberlites were erupted through deformed Archaean basement overlain by volcanic and sedimentary rocks of the Karoo Supergroup. The pipes are located near to the contact between the Archaean Limpopo belt and Zimbabwe craton which forms the suture zone with the Kaapvaal craton. The Limpopo belt (3500 – 2500 Ma) consists of complex metamorphic terrains composed of gneissic, granitic and metasedimentary rocks.

The Orapa kimberlites are characterized by being high up in the volcanic crater area and having had to break through the extensive Karoo-aged basaltic lava flows to reach the surface. The kimberlites are often small in surface area but swell out below the basalts to be much larger than their surface expression suggests. The kimberlites often contain large quantities of fragmented basalt in their upper parts.

First discovered in 1966, the Orapa Regime (cluster) consists of Orapa, Letlhakane and Damtshaa Mines, which are open-pit operations using traditional truck and shovel methods.

The mine plan involves designing progressive “cuts” into the ground, which are developed in a series of “benches”, usually 12-16m in height.

The slope angle of the cut depends on the strength of the country rock mass – the stronger country rocks, e.g. basalt, at the Debswana northern mines, may have slopes of up to 60 degrees, whereas the weaker rocks, such as mudstones, have much gentler slopes, of the order of 30 – 45 degrees.

Today, the area of excavation at surface measures about 120 hectares and the 290m deep pit measures 1.25 by 1.8km.

The tonnes mined from A/K1 pit feed two processing plants, Orapa 1 and Orapa 2. The concept of diamond processing, entails stages of comminution to progressively reduce the particle size of the ore, and screen it into a feed size envelope desirable for the concentration process. A major outcome of the comminution process is diamond liberation; a process whereby the locked-up stones are released from the host rocks. Once the diamonds are liberated, they can now be separated from the gangue material into a concentrate by the Dense Medium Separation process.

Liberation is the fundamental activity of any diamond processing operation. The state of liberation in a plant, while not measurable, is diagnosed by the level of grind (fracture) completed by the plant at any given sub-stage of comminution. The total grind conducted by the plant is achieved by a combination of comminution equipment and recycle such that all material is reduced to below a desired size.

The combin ........