The process of producing gold –
from exploration to the market

We understand that our group has an impact – or the potential to have an impact – throughout the life cycle of our operations. The process of producing gold is described below.

1. 

   1. Finding the orebody

   Identifying targets and undertaking exploration.

   
   
2. 

   2. Creating access to the orebody

   Two types of mining take place: underground mining – a vertical or decline shaft is sunk deep into the ground; and open-pit mining – where the top layers of topsoil or rock are removed to uncover the gold-bearing ore.

3. 

   3. Removing the ore

   In underground mining, holes are drilled, filled with explosives and then blasted; stopes are cleaned and ore is then transported and hoisted to surface. In open-pit mining, drilling and blasting may be necessary to release the gold-bearing rock while excavators load the material onto the ore transport system.

4. 

   4. Transporting broken material to plants for treatment

   Underground ore is transported by means of vertical and/or horizontal transport systems, while open-pit mines transport ore in vehicles capable of hauling large, heavy loads.



5. 

   5. Processing

   Comminution (the process of breaking up ore) occurs in multi-stage crushing and milling circuits, or large mills fed directly with run-of-mine material. For refractory ores (gold locked within sulphide mineral and not readily available for recovery by the cyanidation process) sulphide material is separated using flotation. Sulphide concentrate is oxidised by roasting or bacterial oxidation, to liberate gold. Ore is agitated in an alkaline cyanide leach solution, followed by adsorption of the gold cyanide complex onto activated carbon-in-pulp (CIP). In the heap-leach process, run-of-mine ore is crushed and heaped on a leach pad; low strength alkaline cyanide solution is applied to the top, and the dissolved gold-bearing solution is collected from the base of the heap and transferred to carbon-in-solution (CIS) columns where the gold cyanide complex is adsorbed onto activated carbon. Gold is recovered by re-dissolving gold, followed by precipitation in electro-winning cells and smelting of precipitate into doré bars.

6. 

   6. Refining

   Doré bars are transported to a refinery for further refining, to as close to pure gold as possible.



7. 

   7. Mine-site closure rehabilitation

   Concurrently with mining and once mining has been completed, operations are ‘closed’ and rehabilitation activities return the land to a productive state. (Rehabilitation is the process of reclaiming mined land to the condition that existed prior to mining or to a predetermined post-mining use.) Planning for this process is undertaken during the life of mine.