Namdeb, a partnership between the Namibian Government and De Beers, is one of the biggest exporters in Namibia. It exports diamonds accounting for more than 30% of Namibia's total exports and 10% of gross domestic product (GDP).
Namdeb has spent many years extracting diamonds from Elizabeth Bay security mines in the desert and the sea-bed. The costs involved in shifting the annual 50 to 70 million tons of sand and rock are enormous. Thus, Namdeb is continually looking for innovative ways to improve production and reduce costs.
The challenge
When Namdeb's Elizabeth Bay operation needed a new control room, the operations manager at the time, Ian Holl, gave the consulting company a simple brief: "Give me something from which I can see everything." The result is a building that the staff aptly names 'the E-Bay flight control centre'. Inspired by the control tower at Johannesburg International Airport, this three-storey building on the Namibian coast was designed by a Japanese firm, sub-contracted by Bateman Consulting. The structure has a 270° view of the entire function including workshops, the tipping and crushing site, metallurgy, mining fleet and the whole opencast operation. Now operators can see everything that is occurring - from a truck standing idle that is supposed to be in the field to the processes in the primary crushers and tipping area.
Creating a world-class control room and operations was not an easy feat. Diamonds are literally extracted from the sea floor and the desert's environment poses unique challenges. Dust is stirred by the prevailing wind on the west coast. The prevalence of fog combined with salt laden air offers another challenge in the form of corrosion.
The solution
The tower has three floors with the control room occupying the top floor and housing the LCD screens. The extreme environmental conditions required the use of special frames, designed to eliminate dust ingress, for the control room windows. Because of the east-facing aspect, tinted glass was used. Contrary to expectations of the desert conditions, the temperature is moderate with the average at 18°C due to the proximity of the Benguela current. No extraordinary temperature measures were required in the control room. The floor below the control room is windowless and houses CitectSCADA equipment, PLCs and other hardware in an appropriately controlled environment.
In order to approve efficiencies Namdeb implemented a CitectSCADA solution to enable centralised control of the plant and monitor and control the diamond recovery process. CitectSCADA monitors and controls the processes from the primary crushers and tipping to the diamond recovery plant. Citect installed two redundant servers and two display clients at the mine, which link seamlessly to a 45 000 I/O tag system. At the plant, primary crushers reduce the gravel into smaller manageable sizes. CitectSCADA monitors and controls all field parameters of the crushers, including oil pressures, hydraulic pressure, temperatures, gap sizes of crushers and startup sequences.
Leaving the primary crushers, the gravel is conveyed to the liberation plant where scrubbers and vibrating screens are used to sort and wash it. At this stage, CitectSCADA is used to monitor and control the water flow and start/stop motor sequences. The diamond recovery process at E-Bay uses a lot of seawater in the process. A pump station which is also controlled by CitectSCADA (and Siemens) pumps water from 1,5 km out at sea to the plant. Over approximately nine months, the Citect Professional Services team collaborated closely with Namdeb's Plant and Operations Management, to ensure the system optimises the diamond recovery process at the plant. The result is a highly efficient, low cost extraction process.
Conclusion
Even in its harsh environment, Namdeb remains committed to the highest standards in productivity and safety. Elizabeth Bay Mine has NOSCAR status, one of the highest safety recognition awards in the industry, and has won several prestigious awards, including the Namibia Chamber of Mines Small Mines Competition Shield. The mine has also been awarded ISO 14001 certification for its environmental protection programme.
Namdeb will continue to use CitectSCADA for further plant enhancements and expansions, largely as a result of its exceptional scalability. According to Namdeb project manager, Ian Holl: "Citect's scalability facilitates future plant upgrades without requiring modification to the existing hardware or software. Its single global database simplifies scada software management by allowing changes to be made at a single point that are immediately updated at all Citect stations."
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