Australia is the world’s largest producer of bauxite, and the second largest producer of alumina.
The Darling Scarp contains considerable deposits of bauxite. By world standards, Darling Range bauxite is relatively low grade, but it has the advantage of being cheap to mine and can be digested at low temperatures, which allows economic extraction of alumina. Around 90 per cent of the world’s alumina is smelted to produce aluminium metal.
Darling Range bauxite is found in lateritic areas at or near the surface of elevated terrain. It takes the most common form of pisolitic gravel or a hard outcropping surface layer.
The Felicitas bauxite is typically covered by a thin layer of topsoil and approximately 1m of gravelly overburden. Beneath this, the bauxite layer averages about 3.5m thick.
Mining starts with the removal of any native vegetation in areas not already cleared for farming. The topsoil is then removed and returned to areas under rehabilitation if possible, or stockpiled. Then the overburden is removed and separately stockpiled. Then the bauxite layer is mined. If there is hard material, this is broken using a surface miner before being loaded onto trucks. The bauxite is transported to the crusher (by truck or conveyor, depending on the distance) where it is crushed to meet the customer’s size specification before being stockpiled.
Material is drawn from the stockpile to load onto trains for transport to the customer.
Rehabilitation is done progressively after mining. Mined pits are ripped to improve drainage and the surface is re-sloped to blend in with the surrounding landform. Overburden and topsoil are returned and the area is seeded with species appropriate to the original land use.
We are still doing the feasibility studies for the Felicitas Mine, so the precise methods may change as we work to reduce the potential for impact of our operations outside the mine. In particular we are focussing on ways to reduce noise, dust and water consumption.