Nickolaj Nikolayevich Rulyov
Institute of Biocolloid Chemistry, National Academy of Sciences of Ukraine, Kyiv, Ukraine
Oksana Kravtchenko
Institute of Biocolloid Chemistry, National Academy of Sciences of Ukraine, Kyiv, Ukraine
Fernando Concha
Metallurgical Engineering Department, School of Engineering, University of Concepcion, Concepcion, Chile
Flocculation presents one of the most effective methods for enhancing separation of both anthropogenic and natural suspensions by sedimentation, filtration and flotation techniques.The flocculation effectiveness much depends on the medium shear rate in a flocculator. The objective of this research comprises the study how the suspension dispersity and concentration effect the efficiency of its flocculation in a static tubular flocculator and in a dynamic Couette flocculator. The studies used aqueous suspensions of ultra-fine calcium carbonate (<7 μm) and fine silica (<90 μm) as objects. It was established that treatment of ultra-fine calcium carbonate suspension in a static flocculator produced in the range 400-450 s-1 a pronounced primary maximum in the dependence "flocculation efficiency/shear rate". The increase of the suspension concentration to 70 g/l and above resulted in a small secondary maximum of the flocculation efficiency in the region of around 950 s-1. This can be due to a higher dissolution rate of flocculant and a corresponding increase of particles adhesion forces in flocs, which counteract viscous forces destroying them. In silicon dioxide suspension treatment, the primary and secondary peaks occur at both small and high suspension concentrations, but in a latter case, they are by far more pronounced and comparable in magnitude.
[1] Concha, F. Solid-Liquid Separation in the Mining Industry, 2014, 105. Springer, Cham.
[2] Rulyov, N. N. Ultra-Flocculation: Theory,Experiment,Applications. 5-th UBC-McGill Biennial International Symposium, 43rd Annual Conference of Metallurgist of CIM, 2004, 197–214.
[3] Rulyov, N., Dontsova, T., and Korolyov, V. Ultra-flocculation of dilute fine disperse suspensions. Mineral Processing and Extractive Metallurgy, 2005, 26(3-4), 203–217.
[4] Rulyov, N., Dontsova, T., and Korolyov, V. Separation of fine disperse sorbent from purified water by ultra-flocculation and turbulent micro-flotation. International Journal of Environment and Pollution,2007, 30(2):341-353.
[5] Rulyov, N. N., Laskowski, J. S., and Concha, F. The use of ultra-flocculation in optimization of the experimental flocculation procedures. Physicochemical Problems of Mineral Processing, 2011, 47, 5–16.
[6] Concha, F., Rulyov, N., and Laskowski, J. Settling velocities of particulate systems 18: Solid flux density determination by ultra-flocculation. International Journal of Mineral Processing, 2012, 104:53–57.
[7] Rulyov, N.N., Dontsova, T. A. and Nebesnova, T.V. The pair binding energy of particles and size flocs, which are formed in the turbulent flow. Khimiya i Tekhnologtya Vody, 2005, 27(1), 1-17.
[8] Rulyov, N.N., Korolyov B.Y., and Kovalchuk N.M. Ultra-flocculation of quartz suspension: EFFECTES OF SHEAR RATE, DISPERSITY AND SOLIDS CONCENTRATION, Mineral Processing and Extractive Metallurgy,2009, 118(3):175-181.
[9] Gregory, J., and Nelson, D.W. A new method for flocculation monitoring. Solid-Liquid Separation. Ellis Harwood, Chichester, 1984,172-182.
