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

Paper is not available for download
Contact Us


Cite As:
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), Paste 2010: Proceedings of the Thirteenth International Seminar on Paste and Thickened Tailings, Australian Centre for Geomechanics, Perth, pp. 61-72,

Download citation as:   ris   bibtex   endnote   text   Zotero

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.

Evans, G.V. (1982) The use of tracers in water pollution control, Physics in Technology, Vol. 13, pp. 3–10.
Fernandez-Semperes, J., Front-Montesinos, R. and Espejo-Alcaraz, O. (1995) Residence time distribution for unsteady-
state systems, Chemical Engineering Science, Vol. 50, No. 2, pp. 223–230.
Fernandez-Semperes, J., Front-Montesinos, R. and Espejo-Alcaraz, O. (1996) Authors’ reply to the comments of
R. Ylinen and A.J. Niemi, Chemical Engineering Science, Vol. 52, No. 6, pp. 1069–1071.
Fogler, H.S. (2006) Elements of chemical reaction engineering, Fourth edition, Prentice Hall Professional Technical
Reference, 1080 p.
Grocott, S.C. and McGuiness, L. (1990) Residence-time distribution in Bayer process vessels development of a suitable
liquor tracer, Light Metals, pp. 95–102.
Harrison, E.H., Lépine, A., Gaboury, A. and Thé, K. (1987) The use of sodium nitrate as a tracer in bayor liquor:
analysis by ion chromatography, Light Metals, pp. 95–102.
International Atomic Energy Agency (IAEA) (1990) Guidebook on radioisotope tracers in industry, technical reports
series No. 316, 370 p.
Diagnosis of mud displacement in gravity settlers from analysis of their residence time distribution M.L. Bouchard et al.
72 Paste 2010, Toronto, Canada
Leclerc, A., Boivin, A., Simard, G., Morin, L., Gagnon, M.J., Verreault, R. and Peloquin, G. (2005) Electromagnetic
detection of iron tracers for monitoring particles displacement in gravity settlers, in Proceedings 7th International
Alumina Quality Workshop, Perth, Western Australia, pp. 127–130.
Levenspiel, O. (1999) Chemical reaction engineering, third edition, John Wiley and Sons, 668 p.
Niemi, A.J. (1990) Tracer responses and control of vessels with variable flow and volume, Isotopenpraxis, Vol. 26,
No. 9, pp. 435–438.
Niemi, A.J. (1977) Residence time distribution of variable flow processes, International Journal of Applied radiation
and Isotopes, Vol. 28, pp. 855–860.
Niemi, A.J. and Ylinen, R. (1997) Some comments on “residence time distribution for unsteady-state systems” by
J. Fernandez-Semperes, Chemical Engineering Science, Vol. 52, No. 6, pp. 1065–1067.

© Copyright 2024, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
View copyright/legal information
Please direct any queries or error reports to