• September 26th, 2018
Login / Register

De Beers Marine Namibia - Making Diamonds Count


De Beers Marine Namibia (Pty) Limited is the exclusive marine contractor to mine for diamonds on behalf of Namdeb. Today the company operates five mining vessels in Namdeb's AtlanticÃÆ'Æ'ÀÃ...ÃÆ''šÃ‚ I licensed area. Catherine Sasman went on board some of the ships to see how offshore diamond-mining is conducted. By Catherine Sasman ORANJEMUND After intensive induction and security checks at the sandy and wind-blown airport just outside Oranjemund, a crew of eight visitors last week embarked an SÃÆ'Æ'ÀÃ...ÃÆ''šÃ‚ 79 helicopter to fly out to sea. About 20 nautical miles (one nautical mile equates 1.82 kilometres) offshore lay a large diamond mining vessel, the Coral Sea, where the copter first touched down on the helipad extending from the ship's nose. Opposite the ship waited the Algoa, a fisheries research boat owned by the South African Government, which is commissioned by De Beers Marine Namibia (DBMN) to examine mined and un-mined areas to determine the impact of mining activities on the marine environment. On board for the month of April, was the German-engineered caterpillar-yellow submersible, nicknamed Jago after a little shark living in the Red Sea, which was prepared for a 120-metre deep exploration of the ocean floor. Almost 100 years after Zacharias Lewala picked up the first diamond at LÃÆ'Æ'Æ'ÃÆ''šÃ‚¼deritz, Namibia's land-based diamond mining is likely to gradually scale down considerably in the next few years, although plans are afoot to find new and innovative ways to mine the remaining land resource. But offshore mining along linear, pocket and submerged beaches has been intensified since DBMN became operational in 2001. And yields from the sea have been impressive. In fact, the company has beaten its carat target every year, and has earlier in the year celebrated its highest production levels to date of over one million carats in 2006. The first marine mining took place in shallow waters nearly 50 years ago when Texan businessman, Sammy Collins, with his company, Marine Diamond Corporation, brought in a ship with a sucking machine that hoovered the seabed. In 1983 the De Beers Marine South Africa was formed. In 1990, Louis G. Murray made the first production of 29ÃÆ'Æ'ÀÃ...ÃÆ''šÃ‚ 000 carats from the AtlanticÃÆ'Æ'ÀÃ...ÃÆ''šÃ‚ I - the licensed area currently being mined off the south-western coast of Namibia - which followed full-scale, deep-water mining operations. The mining area lies within a high wave-energy coast with strong southerly winds blowing throughout the year. This results in the upwelling of cold, deep water of about 14 degrees Celsius, which is a biologically productive system that supports commercial fishing. It is for this reason that the DBMN closely monitors its activities for potential consequences on the dynamics of the ecosystem. While little is known about the ocean floor, the rehabilitation process of mined areas occurs naturally, unlike land-based mining, said Fiona Olivier, DBMN's Environmental Manager. She commented that there is no active rehabilitation of the disturbed seabed. Natural disturbances along the mining area occur as a result of seasonal or periodic environmental variations when animals and their habitats are influenced by currents, oxygen concentration and the settlement of sediments re-suspended by storms. These are regular occurrences, as are upwelling and sulphur eruption events and the settlement of sediments carried by the Orange River. Studies have shown that mining in the ocean has a very localized negative impact on hard and soft bottom communities. Full recovery of a mined area reportedly takes place over four to eight years. A few hundred species live on the seabed, ranging from crabs to prawns, starfish, anemones, brittle stars, minute snails, schools of sardines and octopus. Bigger animals in the area are seals and periodic sightings of dolphins and whales. "No rare animals are threatened," observed JÃÆ'Æ'Æ'ÃÆ''šÃ‚¼rgen Schauer, who built and operates the Jago submarine. He had by then made 26 dives with geologists and other scientists monitoring the area since the beginning of April. The small three-ton submarine, which can only accommodate two people at a time, is a reliable tool for deep-water observations, close-up photography and documentation. Its limitation is that it cannot operate in strong winds and high swells which affect the undercurrents and make visibility virtually impossible. But the submersible has had some luck during the visit with calm, flat days. The scientists also use two autonomous underwater vehicles (AUVs) - of which two of the three AUVs in the world are mounted on the Algoa - to acquire detailed, high-resolution images of the seabed. Mining in an eco-sensitive area does have an impact, commented Shauer. "It is like a storm in a coral reef, but things grow fast afterwards." He reported that smaller fish would often find new habitats in burrows formed after mining, and that the areas are rich in algae. Vicky Niku-Paavola, Deputy Diamond Commissioner of the Ministry of Mines and Energy, after having gone down in the Jago, reported that the geomorphology at land was represented as a "mini landscape with yellow colours, mini sand dunes and drop stones distributed sparingly". She further observed rocks covered by fine, yellow, clay materials and mini plants the size of up to two centimetres, such as sponges and white corals "in a fashion of the desert environment". Animals viewed were two types of calamari: the one type appearing translucent and reflective, and the other changing from red to white in the spray lights of the Jago. Other common species seen in the depths were shrimps, each about one centimetre long, swimming by in thick, dark clouds, small crabs crawling in the sand and clay dust at the bottom, hake and Jacopiva fish. "As the Jago moved from the virgin (un-mined) areas, the geological set-up remained unchanged," reported Niku-Paavola. "Clay materials were easily taken into suspension as the Jago passed in the mined areas. Corals were observed as white spots re-growing on the rocks in the mined areas. Wildlife was also observed in both areas." Of concern, said Olivier, are the long-term effects of tailing plumes of discharges in the ocean from the sides of drilling ships. These plumes are the suspended fine-grained sediments that are discharged from the mining vessels back into the ocean. Although these contain no toxic substances, the settlement of these sediments on the seabed impacts on the life around it. The potential impacts on the water columns are a reduction in light for photosynthesis, an increase in food for filter feeders, and the effects of sediment-driven nutrients on microbial activities. These are, however, considered of low significance and limited in timescale. Less than 4.5 square kilometres are mined per year, and about 22 square kilometres have been mined since 1991. It is calculated that about a 52-square-kilometre area - which constitutes 0.8% of the Atlantic I mining licensed area - have been disturbed by tool action and plume settlement. On board the Debmar Pacific, which has a drilling capacity to treat 70 tons per hour, Captain Peter Cook explained that all drilled-up material larger than 50 millimetres get discharged back into the ocean. According to Oscar Petersen, Marine Production Supervisor on the Debmar Pacific, 99% of the deposits are free of chemicals. The five mining vessels drill and crawl and suck the ocean floor with huge tonnage machinery every hour of every day of the week. The mining operation involves the removal of unconsolidated seabed sediments which are airlifted to the surface. At sea, the diamond plant is on deck, unlike land-based mining. Each vessel is a mine, where diamond recovery involves crushing and screening, and at the end of the production process the diamonds get packed into aluminium fruit cans to be airlifted to Oranjemund, and eventually get sorted in Windhoek. Because of this, extremely tight security measures are implemented throughout. During 2005/06 four cases of diamond theft had been reported, and all were apprehended. But much less theft has so far been reported in the marine diamond mining sector than land-based mining. "Someone dealing in diamonds may get 10% of the value on the black market," said Captain Cook. A possible deterrent for theft is that the DBMN pays out 30% of the value when people report picked-up diamonds. The future of marine diamond-mining looks promising for at least the next 100 years. Its contribution to the Namibian economy has been significant, with its 2006 revenues exceeding N$2.6ÃÆ'Æ'ÀÃ...ÃÆ''šÃ‚ billion with subsequent royalties of just over N$260ÃÆ'Æ'ÀÃ...ÃÆ''šÃ‚ million directly to the government coffers. The DBMN contribution to Namdeb's profit was just under N$700ÃÆ'Æ'ÀÃ...ÃÆ''šÃ‚ million. The company continues to manage the resource offshore with innovation and due regard to the environment.
2007-05-02 00:00:00 11 years ago
Share on social media

Be the first to post a comment...