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FIRE IN THE EARTH
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Day after day the loaded cars stream to the shaft and the skips race up and down like mad.
Today
the hazards are few. Humming electric pumps force seeping water out
before it can do any damage. Dust is damped with little streams of
water running through hollow drill-bits. Timber is expertly placed and
replaced wherever necessary. The main level has an underground
hospital, and safety is the watchword.
But
if the visitor to the mine sees no diamonds he should bear in mind that
many of the miners, toiling underground for thirty years, have never
seen one either! Sharp-eyed as hawks, they occasionally see a bright
stone sticking out of a chunk of the blue, but usually there are
diamonds all about them and they are not actually aware of it. The
science of mining engineering takes care of that.
The
next operation, and those that follow, take place above ground. Let's
follow the "skip" and see what becomes of its contents. Taken to the
mill, the rock passes through a maze of machinery. Massive rollers
reduce it to the size of apples, then walnuts, then beans. It is shaken
through flat screens and round screens of all kinds and sizes. It
passes into great circular pans, where it is mixed with water and
revolving toothed arms sweep away the lighter particles. It goes now
into "jigs": vats of water sloshed up and down by plungers, where the
light "ground" washes over the rim, and the heavy material is drawn off
the bottom. And from those several machines, 99 per cent of this blue
rock is sent to a mountainous "tailing dump" and thrown away. It is
worthless.
The
part which is saved is called the "concentrate." It consists of only
the heaviest particles. This is carried to a long room where under a
maze of belts, girders, and pulleys are eighty or ninety
strange-looking, oblong inclined tables.
(34)
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