Slicing Up Quartz

Hawke's Bay Herald-Tribune, Issue 69, 8 April 1937, Page 13

Slicing Up Quartz

, New Cutter May Change System of Mining

JN an offlce high above Holborn Viaduct yesterday I had demonstrated to me a diamond-studded ore-cuttlng wheel v which aeems destined to revolutioniBe twining methods on the Rand, and even to have a profound influence on quarrying and mir>ing at home (says a writer in the Observer). The wheel at flrst sight appears to be a comparatively staple piece of metal work. Actually some of the wheelsrfihown "to me were "gOld cutters," with the me,tal — iron or steel— impregnated, by heating and hydraulic treatment, with the powder of small diamonds so that a hardness is created that no known surface can resist. In a recent test in South Africa a -gold cutter" of this type, mounted exactly on the same principle aS a coalcutter, revolved at 4,000 revolutions a minute and cut through quartz as though lt had been cheese. ' To extend the analogy, in proof of the qualities of the cutter, wafers of porcelain, "pencils" of plate-glass, cubes and sticfcs of Scottish and^ Cornish granite, and layers of Scottish whipstone, which had been sliced with the ease of a baconcutting machine, were ^roduced for my inspection. CLEAN CUTS. TTKE cuts were clean and straight, for all the world as if the resistauce had been mereiy that of a lump of butter. With this invention it is hoped to cut out the gold-bearing banket of the Rand into slices or blocks, and if success is gained when large-scale operations are attempted — small-scale o pefations have been signally successful— the saving in costs and life and limb will be incalculable. The cutting wheels shown to me were of 3in. and 6in. sizes. Larger ones are made ln segments, after the diamonds have been crushed and "oiled" into the metal, and then fixed on the operating Shaft. Tungstone carbide, harder than any steel, and incapable of being effectively ground, can be sliced in a few secondf leaving a flne, mirror-like surface. The tapregnated wheel can be ftxrri as a crown to drilling rods for prospr-tnr-2,000 to 3,000 feet in the earth. brmgu "to bank" sections of strgta much on i principle of an apple-corer. Detn strated on churt, the hardest rock on

Rand, the machine astonished Government officials and mining engineers. It literally cut this rock into wafers with the greatest of ease. And yet those responsible for the invention and its manufacture maintaln a monumental modesty, and are commendably restrained when they refer to it. I was shown a box full of these diamonds—' "dead" stones of no luxury value, completely deflcient of lustre, looking more llke stray pebbles from a quarry. Thferein lies a great economic problem which the invention will probably solve, for lt may provlde a market for huhdreds of thousands of carats of-low-grade stones for which there is at present little demand. NEW PATH OPEN. JN eflect, a new path seems open which will relieve the market of a glut of industrial stones, and undoubtedly that is what is in the minds of the sponsors of the "gold cutter." "There ls no end to the possibilities of the industrial use of low-grade diamonds," the official said. "Tools made with the use of diamond dust impregnation are qulcker, surer and last longer. We now have small drills for use on hard quartz necessary in the optical business. "We have implements for dentlstry which make for steadier and swifter work, apd do uot 'jump' when used for cutting and fllling. Diamonds have also been Impyegnated in bakelite for polishing purposes. EASIER AND SAFER. "AS regards general mining and ^"quarrying, the cutter will be of use when hard obstacles are encountered, and undoubtedly much blasting will be obvlated. In other cases it will make the operation of blasting easier and safer." There have been many changes in mining practice on the Rand, but that pronjised by the ' present invention is iikely to have the greatest effect on the industry Already British, South African and Belgian scientists are devising methods for adapting the machine in handy form for underground work, xnd although some time may elapse •:Uore the industry can adapt itself to ■ ?ec lechnique, there is little doubt that X appreciates the coming of "» mining liracle."