Mining in South Africa.
Roger Gibson gave a presentation to Rotary Alexandra members on Mining in South Africa. South Africa is home to over fifty gold mines, some of the deepest in the world, mining deep level hard rock. Gold seams are embedded in quartz, covered with multiple layers of sedimentary rock. The Western Deep Level mine, part of Witwatersrand complex goes down to a depth of 8,000 feet, and employed 30,000 people. It took one and a half hours to travel from the surface to the work site, then six and a half hours work before returning to surface. Gold was removed from the seam by blasting, so all workers had to clear the blast sites before detonation of explosives.
Underground, the temperature rises by 1C for every 1,000 feet deep. Rock temperature at bottom level of the mine was 55C. There are risks to miners from adiabatic compression, so shafts and leads were reinforced with eucalypt timber. Ventilation was vitally important for those working underground. An underground massive refrigeration plant pumped cold water through lagged pipes to cool the air into the working areas of the mine - it produced 8,000 tons of ice each day. Drilling and blasting into the hard rock produced 300,000 tons of ore per month which was chemically processed using cyanide to extract the gold.
To conclude his talk, Roger read one of his poems:
Down the Mine
Descending down, deep, harsh and bleak
Beneath the bare and hard-rock hanging,
The twisted timbers brace and creak.
Bright light beams strobe the solid dark
As watchful eyes, of those who work
Search for wealth in winding mazes.
With dripping sweat on red-hot skin,
In narrow stopes and long hot raises
The strident screech of drills unfolds
The rich reefs guarding hidden gold.
With heaving chests, in stifling heat,
Deft hands set lethal nitro charges.
Ignite the fuses! Quick! Retreat!
Explosive blasts  shake acrid air
With pulsing surges. Beware! Take care!
Climbing upwards to dazzling light
as fresh air fills, now, gasping lungs;
out of the mine, blue sky in sight,
refreshing showers, then homeward bound
to loving families, happy sounds…
Prepare for next shift, underground