The mined ore rocks are very large and have to be made smaller. This is done by a machine called a jaw crusher. The resulting smaller rocks are further broken down by cone crushers until each one is only 2cm long.

Step 2: Screening The rocks then go through a vibrating screen. This makes sure that only the smallest, best rocks are taken to the grinding mill. These rocks are transported to the grinding mill along conveyor belts. The larger rocks are carried back to the cone crushers to be made small enough to go to the grinding mill.

Step 3: Grinding Once at the mill, the rocks are blended with water and made into a thick, gooey mixture called slurry. Afterwards, the slurry is passed through a cyclone to separate the different sized particles. Only the finest particles carry on through the process after being screened once more. The courser ones must go back to the mill.

The slurry with particles that are fine enough has cyanide added to it so that its gold is dissolved. To encourage the gold to dissolve, lime is also added. This step is very environmentally friendly because hardly any gas escapes into the air. This is so because the cyanide is consumed in reaction.

In the next step, after the lime is added to it, the slurry goes to the carbon in leach plant. There it’s treated with carbon granules that soak up the gold in it while travelling through large tanks. Each one of these tanks is full of oxygen which helps the gold stick to the carbon granules. Once the slurry is passing through the last tank much of the gold will have been taken away with the carbon granules.

In a pressurised machine called a carbon elution chamber, gold is stripped from the carbon granules. As well as that, the carbon elution chamber adds cyanide and caustic soda and removes water from the gold. After that, the carbon granules are exposed to extremely high temperatures which allows them to be reused. In the last chamber, the gold is adhered to stainless steel electrodes or plated. The gold on the electrodes is washed off them and heated to 1000 degrees C to melt it and at last it’s poured into the moulds which shapes it into gold bars.

By Brittany Ledwell