Optimizing dewatering and soft tailings consolidation by enhancing tailings’ composition Ibanez, Maria; Chassagne, Claire; van Paassen, Leon; Sittoni, Luca
In order to reclaim ultra-soft tailings (e.g. oil sands) ponds great amount of research and technology work has been performed over the years to optimize the dewatering and consolidation of Fine Fluid Tailings (FFT), including the use of different chemical flocculants and mechanical deposition approaches. Yet, traditionally flocculation, hence settling, and consolidation are treated as two independent processes. Here integrate these two processes, proving how implementation of certain types of flocculants influences the consolidation rates and strength of the deposit. Laboratory studies on small scale settling columns carried out at Deltares tested the settling and consolidation rates, and the strength development of FFT samples treated with different flocculants dosage under different water chemistry and pH conditions. These systematic tests revealed distinct correlations between flocculation and consolidation and strength properties. These studies also enabled us to find specific laboratory and analytical tools to assess the relevant properties of the tailings. We will show that using what is generally called "zeta potential” (in fact “electrophoretic”) measurements allow obtaining fast and reliable information about the tailings’ composition, such to estimate the required flocculant dose to optimize geotechnical properties. This, combined with the analytical methods to estimate consolidation rates from settling column, allowed us to distinctly correlate flocculation with consolidation.
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