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The accumulation of salts on the surface of thickened tailings is well-known to suppress evaporation and
consolidation, thereby having both negative economic and environmental implications for surface deposition
operations. The current research studied and related the 1D mass transport of dissolved solute within a layer
of acid-generating thickened gold tailings to salt crust formation and evaporation using a model wax column
technique. The electrical conductivity, matric suction, total suction and gravimetric water content at 1 cm
intervals of a column of desiccating thickened tailings was determined over a period of 15 days and related
to measured evaporation rates over the same period. Results from this paper showed evidence of salt
accumulation at the top 1 cm of thickened tailings layer, which reduced the rate of evaporation after
12 days. Osmotic suction was observed to be the major mechanism of reduction in evaporation rate by salts,
as opposed to any physical crust effects. Therefore, it may be possible to anticipate suppression of
evaporation by salts through modelling ion transport, a technique that could be used to optimise thickened
tailings deposition schemes with respect to controlling salt accumulation.
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Solute mass transport and atmospheric drying of high-density gold tailings A. Dunmola and P. Simms
290 Paste 2010, Toronto, Canada