The need for fertiliser

Iron sulfide (pyrite minerals) was extracted from Brukunga from 1955 to 1972. The sulfur was the key ingredient for the production of sulfuric acid needed for the manufacture of superphosphate fertiliser. The superphosphate fertiliser was used to sustain the rapid expansion in agriculture that occurred in South Australia following World War II.

Sulfidic waste

In the mine’s 17 year of operations, a great deal of sulfidic waste accumulated on site including (approx.):

• 8 million tonnes of overburden and waste rock (2% sulfur) was excavated and discarded into two large rock-dumps
• 3.5 million tonnes of sand-tailings (1.7% sulfur)

Abrupt end to operations

As a result of cheaper international sources of sulfur and the cancellation of the national government’s pyrite subsidy, mining operations stopped abruptly on 31 May 1972. Water emanating from the site was collected in an evaporation lagoon on the tailings storage facility (TSF) to the east of the mine.

Acid and Metaliferous Drainage (AMD)

When the mine closed, fresh sulfidic minerals (pyrite and pyrrhotite) were left exposed on the surface in the floor of the quarry. When exposed to air, water and bacteria, these sulfidic minerals oxidise and break down to form acid drainage. The acid conditions enable various heavy metals within the minerals to dissolve into the ground and surface water. The resultant seepage contaminates the flow of Dawesley Creek as it passes through the mine site.

In February 1974, a severe weather event caused the evaporation lagoon to overflow and polluted Dawesley Creek for a significant distance downstream of the site.

Change of ownership and remediation activities

In August 1977 the State Government accepted responsibility for managing all environmental issues at Brukunga.