Yuan, XS, Bara, B & Siman, R 2013, 'Development of success criteria for high density fluid fine tailings flocculation in the oil sand industry', in R Jewell, AB Fourie, J Caldwell & J Pimenta (eds), Proceedings of the 16th International Seminar on Paste and Thickened Tailings
, Australian Centre for Geomechanics, Perth, pp. 147-159.
Syncrude Canada Ltd. is currently developing multi-pronged technologies to treat its legacy fluid fine tailings (FFT). FFT centrifugation, thin-lift and thick-lift (Accelerated Dewatering with rim ditch) are three key technologies. They all require proper mixing and flocculation of high density FFT with a polymeric flocculant. It was found that the previously developed criteria to determine the flocculation performances for the well-diluted tailings systems used in thickeners were not valid for the flocculation of high density FFT due to high viscosity of FFT. The success criteria for high density FFT flocculation were identified as a technical gap that must be closed before FFT centrifuge commercialisation. This paper deals with the development of the success criteria to benchmark the mixing and flocculation performances of high density FFT. The instruments and methodologies used to determine the success criteria will be presented and discussed. It was concluded that four criteria, i.e. yield stress, capillary suction time (CST), lab centrifuge index and visual floc structures of the flocculated materials, were successfully established to determine the performances of high density FFT flocculation. These four criteria are all related to each other. Yield stress indicates the strength of the flocculated material, CST shows the relative dewatering capacity, the lab centrifuge index quickly determines the processibility of solids-liquid separation at a given centrifugal force and time, and the floc structures visually demonstrate the floc sizes and networks. In general, for a good flocculation the flocculated material exhibits a higher yield stress, a lower CST, a clearer centrifuge centrate, and a larger visual floc size. They are just vice versa for a poor flocculation of high density FFT. A few case studies will be used to verify the applicability of the four criteria for high density FFT flocculation. These criteria have been used to gauge the FFT flocculation performances in Syncrude 2010 and 2011 FFT centrifuge pilot tests.
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