Authors: Bouchard, ML; Leclerc, A; Simard, G; Peloquin, G

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Bouchard, ML, Leclerc, A, Simard, G & Peloquin, G 2010, 'Diagnosis of mud displacement in gravity settlers from analysis of their residence time distribution', in R Jewell & AB Fourie (eds), Proceedings of the Thirteenth International Seminar on Paste and Thickened Tailings, Australian Centre for Geomechanics, Perth, pp. 61-72,

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Knowledge of the residence time distributions (RTD) of solid particles through gravity settlers of the Bayer process is essential to verify that they are operated effectively. Moreover, the RTD may be used to diagnose some common problems occurring in settlers, like channelling and dead zone or to evaluate the effectiveness of certain operational parameters, such as rake configuration. Because of the aggressive chemical environment of the Bayer process it is difficult to realise RTD measurements. To monitor the mud displacement, a ferromagnetic iron tracer was used with a new on line electromagnetic inductance measurement method that has been described previously. Sedimentation tests performed in a laboratory settler confirmed the effectiveness of this approach. In addition, a new method of RTD curves’ decomposition has been used in order to facilitate the analysis of the data. This paper describes briefly the experimental apparatus and presents an analysis of the RTD data obtained with our laboratory settler based on this novel curve decomposition technique.

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