| Popis: |
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. |
