The typical composition of the Gidji plume does not change however it can appear darker under particular atmospheric conditions. Wind strength, plume dispersion, atmospheric temperature and the presence of cloud can all contribute to colour perception. Sun angle is also an important variable. Particles and gases in the plume scatter, reflect and absorb light, resulting in an apparent brown colour.

The AQCS allows for restricted roasting to occur when the winds are in a northerly arc. At all times the operations of the Roaster are carefully monitored and managed.

• SO2 is used as a fruit preserving agent and as a food preservative or additive.
• SO2 can be emitted from fossil fuel power plants, wood pulping and paper manufacturing processes, decaying vegetation and volcanic activity
• It is used in the fermentation stage of wine making, for bleaching textile fibres, in the manufacture of paper, as a disinfectant in breweries and food factories, and as a fumigant for grains, grapes and citrus fruits.
• SO2 is a common substance to which we are exposed at very low levels every day by breathing air in cities, with vehicle exhaust being a significant source of SO2

• The Gidji stack is approximately 180m tall.
• The roaster is operated at 650°C, so much heat is generated that this temperature has to be controlled by the addition of cooling water.
• Approximately 4,000 hours of roasting are lost each year due to AQCS restrictions for certain atmospheric conditions.
• The concentrate is self-combusting, once the right temperature is reached the concentrate ignites and continues to burn due to a heat generating chemical reaction inside the roaster.
• Gidji employs 33 local people as well as additional contractors.