Mining sludge is the waste product of alluvial mining, and in particular
hydraulic sluicing. It has been particularly prominent in gold fields in Australia and California in the nineteenth century.
[cyanide process
Gold cyanidation (also known as the cyanide process or the MacArthur-Forrest process) is a hydrometallurgical technique for extracting gold from low-grade ore by converting the gold to a water-soluble coordination complex. It is the most commonl ...]
also involved releasing sediment contaminated with cyanide, while other sludge deposits have a variety of contaminants used in the mining process.
Large areas of land were affected by sludge, particularly in Victoria, where a
was established in 1858-9 to investigate and manage the problem. This resulted in a number of regulations and the construction of large stone-lined sludge channels to concentrate and divert the sludge away from settled areas and buildings. the towns of Bendigo, Ballarat, Castlemaine, Creswick and Maryborough have channelized streams running through them as a result.
Ultimately hydraulic sluicing was banned in 1904 as a result of the continuing environmental damage caused to waterways in places such as
, and a Sludge Abatement Board was established to regulate and repair the problem.