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Gold/Mining/Energy : SOUTHERNERA (t.SUF) -- Ignore unavailable to you. Want to Upgrade?

To: Gord Bolton who wrote (2163)	11/5/1998 12:07:00 PM
From: Goalie	Read Replies (1) \| Respond to of 7235

Thanks, Gord! Some problem!!!! Gotta love it!!! The unkindest cut De Beers puzzles over diamond breakage at Marsfontein September 28, 1998 -- While Toronto's SouthernEra Resources Limited continues to swamp the market with heady press releases (149,595 carats in the first 17 days at the M1 pipe!), another, more secretive process gets underway. De Beers technicians in Johannesburg have begun to examine certain stones from the M1, and the conclusions they draw will help determine, among other things, whether the deposit is even richer than original sampling indicates. On September 8 SouthernEra, announcing another glittering return from the M1, included news of the recovery of a stone weighing 99.6 carats. Although SouthernEra said little about it at the time, the stone is reportedly of good color, with internal fractures. But there's something even more important. The M1 stone is broken: It was part of a larger stone. This realization triggered the involvement of a man with a very narrow specialty - diamond breakage. Now that the bloodbath legal fight for control of the M1 is over (see Marsfontein agreement ends backroom brawl, June 15), SouthernEra can begin to enjoy the benefits of its joint venture relationship with senior partner De Beers Consolidated Mines. One of the benefits of that relationship is Derek Robinson. Robinson is a diamond-breakage expert. He must answer this key question: Was the 99-carat stone broken, say, 100 million years ago by the violent forces of geological formation, or did the miners accidentally break it when they dug it up? "More likely, we did it," says Kim Freeman, SouthernEra's chief mining engineer. "You can see it's a fresh fracture." If Robinson's research and subsequent intelligence about the pipe confirms this suspicion and the operators establish a significant population of larger stones, there are immediate engineering consequences. "It means we have to do something about the front end of the plant," Freeman says. One of the first things a diamond recovery plant does is chew through the ore and crush it, allowing only rocks of a certain size to advance into the plant. If, for example, sampling indicates a diamond population that does not have diamonds or diamond-bearing stones greater than 25 mm wide, then the initial screening and crushing will try to keep anything bigger than that from coming into the plant. But if there are gemstones larger than 25 mm, then you want to make sure you 're neither throwing them out with the tailings nor breaking them in your 25-mm crusher. If you've got the Hope diamond, you don't want to smash it until it's on the diamond cutter's bench. Right now, SouthernEra's mill crushes anything over 25 mm. The investigations under way in Johannesburg, then, will help decide whether that cut-off should be increased. (The 99-carat should have made it thorough the present screen. A cube-shaped 99-carat would have one dimension of 17 mm; a spherical 99-carat would have a 22-mm diameter. A 200-carat sphere, on the other hand, with a diameter of 28 mm, would either get crushed or tossed. And you don't want to be tossing out 200-carat stones.) It comes down to three "ifs": If M1 has large diamonds being broken in recovery, if there are enough of them, and if they're worth enough, then the joint venture will modify the plant to start admitting larger rock. "It is in the interest of the Marsfontein joint venture that damage to diamonds during the mining or recovery process is minimized," says Tracey Peterson, a De Beers spokesperson. "Every diamond mine's ore dressing 'profile' is different, and mining and recovery processes are designed accordingly. "As is the case on De Beers' other diamond mines, where the search for excellence in the metallurgical processes is ongoing, the recovery processes in use at the Marsfontein mine are being monitored to ensure that the many different factors which influence liberation and recovery efficiencies, including diamond damage, can be fine-tuned." Stay tuned for updates on the M1 stones. __________________