The effects of cracks on the movement of Ca+2 within gold refining residue
Pratt, A., Samaraweera, S. and Bell, R. (1997) The effects of cracks on the movement of Ca+2 within gold refining residue. In: Soils '97 : proceedings of the fourth triennial Western Australian Soil Science Conference, 30 September - 2 October, Geraldton, Western Australia
Gold refining residue is alkaline (pH> 9), saline (EC1:5: 800- 1100 mS/m) and sodic (ESP>60) (Ho et al., 1998). These chemical properties have a detrimental effect on residue physical properties (hydraulic conductivity, bulk density, porosity). Together these properties limit the potential for revegetation.
Gypsum (CaS04.2H20) has commonly been used to reclaim alkaline, saline and sodic soils (Charters, et al., 1985). However, these studies, in addition to that conducted by Alva and Gascho (1991 ), have reported that the vertical depth of amelioration is generally limited to the depth of gypsum incorporation in clay soils. These researchers attribute the negligible leaching of Ca2+ to the low hydraulic conductivity and strong adsorptive capacity of clay soils.
The importance of cracks (or macropores) on the vertical movement of water and solutes through soil profiles has been extensively studied (Logsdon, 1995). Schuman and Meining (1993) observed that the vertical movement of Ca2+ was greatly enhanced by the presence of cracks within sodic bentonite spoils. It is therefore the objective of the present study to determine whether cracks in gold refining residue, formed as a result of solar drying, facilitate Ca2+ movement to greater depths in the residue profile than the depth of incorporation.
|Publication Type:||Conference Paper|
|Murdoch Affiliation:||School of Environmental Science|
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