Mining of Diamond

We shall consider now some of the problems met with ill winning the mineral diamond from the earth. There are in effect two major different kinds of mining operation for re¬covery of diamond. In the one case, the mineral is won from the original virgin deep pipes. In the other, it is recovered from alluvial deposits on the surface (marine off-shore mining is an extension of this). Considerable capital is involved it) both procedures. Historically, diamonds as first found in India and later in Brazil were essentially alluvial deposits, The mining of deep pipes first began round Kimberley in South Africa. Although more diamond is now recovered from alluvial beds than from deep mine pipes, we shall describe pipe-mining operations first by reviewing the operations of the main mines, the de Beers Group in South Africa. Buy wedding bands diamond wedding rings

When the South African diamond rush started (in about 1871) by 1872 there were 50 000 diggers around Kimberley and each was allocated a small plot, a mere 30 feet by 30 feet, separated by 15-foot-wide roadways. Diggers dug down by open-cast mining and inevitably soon began undercutting the neutral roadways, which quickly collapsed. An extraordinary spidery web of rope haulages was constructed to raise ore, but the situation soon became chaotic. Cecil Rhodes quickly realised that the only way to work a mine was to buy out all the prospectors and introduce a central engineering control, This he achieved in 1888, by which date his de Beers Consoli¬dated Mines Company controlled the de Beers and Kimberley mines. They soon acquired the new Dutoitspan, Bultfontein and Wesselton mines, and these five became a centre of development for new mining techniques. The Kimberley and de Beers mines are now closed, but in their place the Jagers-fontein, the Premier and, lately, the Finsch mines have come into operation for the group. Check diamond jewelry if you need diamond rings.

PIPE MINING
Diamonds are found in volcanic pipes of blue rock (kimber-lite), such a pipe being roughly cylindrical, maybe 1000 yards across and going down to an enormous unknown depth. Pipes are almost vertical, penetrating the surrounding rock. As the initial uncoordinated early mining progressed, a deep hole into the earth was created. However, progressively the side walls of the surrounding rock (‘reef’ is the miner’s name

for this) began to fall in and to overburden the blue rock ('blue ground' in miners' terminology). Soon the whole bottom of each vast pit was one enormous accumulation of reef. The only solution was to attack the blue ground from the side and so come in below the collapsed reef. The main shaft is cut about 1000 feet from the side of the mine. At 600-foot intervals tunnels are run from the main shaft, These join a secondary shaft. From this a complex of short tunnels at 40-foot intervals is driven into the solid blue ground which is intact below the mass of reef rubble. These tunnels are developed into a geometrical system of chambers which are created through excavating the blue ground which is carrying the diamond. The excavated ore is loaded into rope, hauled cars and eventually reaches a shaft and then is brought to the surface.
Instead of 'chambering', as it is called, in some mines a modified arrangement called 'block caving' is adopted. In this, material is cut away leaving inverted cones, which in due course collapse and supply the blue ground needed. This material is withdrawn along tunnels by mechanical scrapers, being then pulled into cars for haulage to the surface. Block caving is faster and safer as a method of mining than chamber¬ing and is also more economical to operate. So far, levels up to 2000 feet deep are being exploited. The bigger mines pro¬duce about 4800 tons of ore a day, yet such a quantity of ore may produce a mere 350 carats of diamond, say about 3 ounces of diamond, and this represents total output from a big mine into which much capital has been sunk and which needs a big labour force.