Finding Diamonds in the Rough Seas

by on December 4, 2008 at 5:51 am

For the 60 men and three women aboard the Peace of Africa, diamonds aren’t a luxury, they’re a career choice. Finding the gems requires  the latest technology and creates a Jacques Cousteau-like adventure.

The Peace of Africa is a $1 billion South African rand ($110 million U.S.) piece of high-tech engineering designed to maximize the yield of precious gems from the ocean floor at a minimal cost and impact. The process may seem simplistic — find diamond “hot spots,” scrape along the floor to loosen the gravel and minerals, vacuum up the mess, and sort through what you got. The mining operation has been fully automated so that no human hands touch or even see the diamonds until they reach a secure facility on shore.

The system processes about 10,000 cubic meters of water and minerals per day. First the minerals are washed and then dried, and sorted to identify the materials most likely to be diamonds. The pieces are then x-rayed to illuminate the diamonds so that they can be identified, and then immediately spit out of the system and canned and sealed without a finger being laid on them.

One of the biggest challenges is figuring out what to keep and what to throw away, according to Elizly Steyn, the ship’s metallurgist. Steyn works for the De Beers Group, the diamond business that own and operates the ship. She’s part of a team that monitors a steady stream of data to optimize the diamond yields. The company’s target is 1000 carats of diamonds per day, or 200,000 carats per year, which includes down time for maintenance, technical glitches, and bad weather. Based on the information collected from the sonar scanning, automated underwater vessels, and real-time analysis, the filtering system is set up to only extract pieces between 2 and 19 millimeters in size, Steyn says. This results in the largest diamonds automatically being tossed overboard — not what you would expect. “It would cost more to process the additional material than you’d get back from the one large diamond you might find every six months,” says Steyn.

The diamonds were formed about 2.2 million years ago, and then thrust to the surface by volcanoes around 700 million years later, according to Tom Tweedy of De Beers. He says that while diamond mining started in South Africa about 100 years ago, no one bothered to look under the ocean until a Texas oil man suggested doing so in the 1960s after diamonds were found on the shore. The diamonds are harvested by “the crawler,” a remote controlled bulldozer-like vehicle that rests on the ocean floor and scrapes the bottom until the clay is reached. Steyn says only the occasional fish gets caught up in the vacuum. Most of the sea floor at around 125 meters is barren of vegetation. The crawler costs about $1 million U.S., so it is too expensive to keep a spare on board. When it stops working, as happened during our visit, so does the mining operation.

The crawler takes about 1 1/2 hours to retrieve and return atop the Peace of Africa, which is anchored about 10 miles off the coast. The waste water and minerals are automatically pumped to the side of the ship and eventually resettles on the bottom. The dolphins don’t seem to mind the brown cloud this creates, as a group of about half a dozen was hanging out by the side of the vessel during this reporter’s visit.

Another impediment to mining is the stormy weather off the coast near the South Africa-Zimbabwe border. Swells sometimes reach 27 meters in height, which shuts down operations as it is too strong for the flexible hoses that connect with the crawler below. Only when waves surpass 14 meters does the mining operation shut down. All of the equipment — the engines, the winches that maneuver the crawler and position the ship over the crawling area, and the machines that pump and sort the materials — run on electricity. The engines run on a fuel oil that is slightly thicker than diesel, and burn through between 18 and 30 tons of fuel each day. That’s the equivalent of filling up the gas tanks of about 600 cars per day. De Beers has an environmental officer dedicated to studying the ship’s impact on the ocean and air. The engines were tested to meet the government’s requirements for NOx and SOx emissions. While the air quality within the working areas of the ship is not monitored for emissions, an air filtration system cleans the air in the living quarters, according to Steyn. The ship’s crew stays on board the ship for 28 days and then gets 28 days off.

That schedule is just fine with Steyn, who plans to stay on for another two years. She grew up with three older brothers and is used to hanging out with the guys.

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