Abstract
Mineral suspensions in water show Newtonian flow properties at low percent solids. However, this changes to a non-Newtonian regime as the percent solids increases. For Newtonian fluids, viscosity is independent of shear rate, but, for non-Newtonian fluids, viscosity varies with shear rate. Therefore, if the slurry is non-Newtonian, attempting to measure the viscosity at a shear rate different from the shear rate experienced by the fluid within the process is futile. This is especially true for a hydrocyclone, where the rate of shear is different at different points within the hydrocy clone. In this case, it is very important to determine the flow type of the suspension before attempting to establish any correlation between the viscosity and the process efficiency.
A new technique to distinguish such changes inflow type was developed. This involves two viscometers: a coaxial cylinder-type viscometer that measures apparent viscosity at low shear rates and a vibrating sphere-type viscometer that measures the apparent viscosity at high shear rates. For each of these instruments, special precautions were taken to allow for the measurement of the viscosity of rapidly settling mineral suspensions. Because the vibrating sphere viscometer is operated at a much higher shear rate than the rotating viscometer, the two instruments together could determine the shear-rate dependency of the viscosity. Ground silica (80% passing 65 µm) in water was used to prepare slurries at concentrations ranging from 10% to 70% (by weight) solids. The viscosity of each slurry sample was measured simultaneously by both viscometers, and the results were compared. With this technique, it was found that all of the silica-slurry samples tested were in the Newtonian flow regime for up to 70% (by weight) solids. Methocel and Cellosize polymer solutions showed clear non-Newtonian behavior using this technique. This confirmed that non-Newtonian behavior of the silica slurries, if pre sent, would have been detected by this arrangement.
Similar content being viewed by others
References
Agar, G.E., and Herbst, J.A., 1966, “The effect of fluid viscosity on cyclone classification,” Transactions, AIME, Vol. 235, pp. 145–149.
Bakshi, A.K., 1996, “An On-Line Rheometer for Particulate Streams — Theory, Development, and Plant Testing,” Ph.D. Thesis, Michigan Technological University, Houghton, MI.
Bradley, D., 1965, The Hydrocyclone, first edition, Pergamon Press, New York, NY. Dow Chemical Company, 1988, Technical Handbook, Methocel Cellulose Ether, Midland, MI.
Ferry, J.D., 1977, “Oscillation viscometry-effects of shear rate and frequency,” Measurements and Control, Vol. 11, No. 5.
Klimpel, R.R., 1982, “Slurry rheology influence on the performance of mineral/coal grinding circuits, Part I,” Mining Engineering, Vol. 34, No. 12, pp. 1665–1668.
Klimpel, R.R., 1983, “Slurry rheology influence on the performance of mineral/coal grinding circuits, Part II,” Mining Engineering, Vol. 35, No. 1, pp. 21–26.
Lynch, A.J., and Rao, T.C., 1975, “Modeling and scale-up of hydrocyclone classifiers,” Proceedings of the XI International Mineral Processing Congress, Cagliari, pp. 245–269.
Plitt, L.R., 1976, “A mathematical modeling of the hydrocyclone classifier,” CIM Bulletin, Vol. 69, pp. 114–123.
Rusesky, M.T., 1989, “On-Line Slurry Viscosity Measurement and the Effect of Rheological Factors on Hydrocyclone Performance,” Masters Thesis, Michigan Technological University, Houghton, MI.
Schack, C.H., Dean, K.C., and Molly, K.C., 1957, “Measurement and Nature of the Apparent Viscosity of Water Suspensions of Some Common Minerals,” Report of Investigations, RI 5334, US Bureau of Mines, May.
Union Carbide Corporation, 1987, Cellosize Technical Handbook, Specialty Chemical Division, Union Carbide Corporation, Danbury, CT.
Author information
Authors and Affiliations
Additional information
SME preprint 95-33, SME Annual Meeting, March 6–9, 1995, Denver, CO. M&MP paper 95–626. Discussion of this peer-reviewed and approved paper is invited and must be submitted, in duplicate, prior to Feb. 28, 1997.
Rights and permissions
About this article
Cite this article
Bakshi, A.K., Kawatra, S.K. Rapid determination of non-Newtonian flow behavior in mineral suspensions. Mining, Metallurgy & Exploration 13, 165–169 (1996). https://doi.org/10.1007/BF03402740
Received:
Revised:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF03402740