The Venetia Process Plant incorporating Bateman machinery. Diamond mining and recovery is a clean operation. Processing of the ore uses no toxic chemicals and produces no chemical pollutants.
Venetia is a conventional open-pit mine. Surface mining is expected to carry on for some 20 years and, as the mine becomes deeper, the feasibility of underground operations are being investigated. The targeted pit floor level was at a depth of 400m. A re-evaluation of the pit design undertaken during 1998 reduced the waste-stripping requirements. In order to reduce waste and realise greater value, some initiatives were brought in to optimise the mine design. This allowed the mine to surpass waste stripping target, and hence improved the overall cost per ton mined.
After waste stripping to expose the kimberlite, the ore is blasted and loaded into trucks, hauled to a crusher, reduced in size and conveyed to a primary stockpile. Crushed ore is then conveyed to the main treatment plant for processing. Key equipment in the pit includes P&H and Reedrill rotary drills and O&K RH200E electric-powered hydraulic excavators, the latter being equipped for monitoring and service purposes by direct radio link to O&K's plant in Germany. Loading and haulage is supervised via a GPS fleet management system. Ancillary equipment includes Bell articulated water bowsers, used for road spraying, vehicle washing and fire-fighting duties.
Diamond recovery
Inside the treatment plant, the kimberlite is further crushed, washed and screened into different size fractions. Dense-medium separation is used to produce a diamondiferous concentrate, which is then subject to X-ray fluorescence sorting to separate diamonds from residual waste. After drying, final hand-sorting recovers the diamonds, which are sent to the offices of the Central Selling Organisation (CSO) in Kimberley for classification into some 5,000 categories based on combinations of size, shape, colour and quality.
The recovery plant includes widespread use of Bateman pneumatic conveying systems for handling concentrates, tailings and products. General spillage is handled by a vacuum clean-up system servicing most of the plant equipment. Consisting of a 2,500m-long pipe network, this has over 700 pick-up/collection points, using a mobile vacuum unit to pick up spillage up to 50mm in size.
Environmental
Venetia is located in an environmentally sensitive area and De Beers spent some R17m on initial environmental engineering projects. The 35km-long water supply pipeline and other service supply pipelines are buried, the mine has a state-of-the-art dust control system, and noise and lighting impacts are minimised. The company also established the 36,000ha Venetia Limpopo Nature Reserve adjacent to the mine and moved a large number of animals from a new mining area to the reserve.
Courtesy www.mining-technology.com |