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Gypsum as an ameliorant for revegetating salt-affected ore refining residues
Conference paper   Open access

Gypsum as an ameliorant for revegetating salt-affected ore refining residues

R.W. Bell, M.K.S.A. Samaraweera, S. Beaton and G.E. Ho
Goldfields Land Rehabilitation Group
1994 Workshop on Rehabilitation of Arid and Semi-Arid Areas (Kalgoorlie, Western Australia, 19/05/1994–20/05/1994)
1994
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Abstract

Revegetation on mine sites and mine wastes in Western Australia commonly has to deal with salt-affected substrates (the generic term substrate includes soils, saprolite, overburden and residues, all of which can be media for plant growth on mine sites) for plant growth. However, the origin of the salt is varied: so too are the treatments to ameliorate the salt-affected substrates for successful revegetation. Salts occur in high concentrations in the wastes from bauxite and gold mining in Western Australia. These mining operations exploit silicate based ores and rely on the chemical extraction of finely ground ore with sodium hydroxide followed in the case of gold ores with sodium cyanide treatment. Thus the process waters which are continually recycled, contain high sodium concentrations and the residue is salt-affected. In addition, in a number of the operations, saline groundwater (e.g. Kaltails operation in the eastern Goldfields) or run-off water (e.g. gold mining operations in the eastern Darling Range) is used in the processing, adding further salt to the process cycle. Apart from the introduction of salts into the process waters, many of the topsoils, subsoils, overburdens, saprolite substrates and waste materials present at mine sites contain sodium salts since nearly one-third of Australian soils are salt-affected (Northcote and Skene 1968). Thus salt constraints will need to be considered in many areas by those attempting revegetation after mining. Salt-affected substrates may suffer from one or more of three conditions: salinity, sodicity and alkalinity. Each has its own special constraints and particular requirements for management or alleviation. In this paper, we will consider each type of salt-affected land and the role of gypsum, calcium sulphate, in its amelioration with particular reference to mine wastes.

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