Glossary of abandoned mines terms

Acid and metalliferous drainage

Acid and metalliferous drainage occurs when naturally occurring sulphide minerals oxidise when exposed to air, forming sulphuric acid. The acid can leach metals from surrounding rock and, as a result, produce water that has a low pH, a high metal content and high sulphate levels.

Capping

Capping is a covering placed over waste rock or contaminated material to prevent water entering and reacting with the material to produce acidic (or contaminated) run-off. The cap can be a variety of material including high-density polyethylene (plastic) liner (HDPE), clay or soil/rock (or a mix of these).

Evaporation ponds

These are large shallow ponds generally used to reduce water volumes by using sunlight to evaporate the water. Water may be process water or mine-affected water.

Hardstand laydown areas

These are hard-surfaced areas for storing heavy vehicles, machinery or materials.

Heap leach/heap leach pads

A mining process where mined ore is crushed and heaped on an impermeable plastic or bitumen lined pad and then irrigated with a leach solution to dissolve the valuable metals before further processing.

Mullock heap

A mound of left-over soil or rock from the shaft excavation process, usually associated with small-scale or historic gold or opal mining.

Open-cut pit

A large void left behind after overburden (soil and rock) and the target ore or mineral is excavated.

Pit cutback area

Benches of land created by the excavation of mining pits.

Potentially acid forming material (PAF)

Material that has the potential to produce acid through the chemical and biological weathering effects of air, water and microorganisms.

Process water dam

A dam used to store water for use in the extraction process.

Processing plant

Building and equipment used to crush ore and separate or extract mined minerals. May contain process chemicals.

Seepage collection sump

A constructed storage pond at the foot of a tailings dam, waste rock stockpile or potential acid forming material to collect any contaminated seepage and prevent it migrating off site, usually by pumping it to a dam or open pit for treatment or storage.

Tailings

Residual fine-grained material that has been crushed and ground and/or washed and rejected from a mill or processing plant after the recoverable minerals have been extracted.

Tailings storage facility (TSF)

A dam, containment cell or other storage holding the tailings or materials left over from mineral processing.

Waste rock

Rock or material overlying an ore or mineral body excavated as part of mining (but not processed to extract mineral) and stockpiled on site.