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Hydrocyclone efficiency

University of British Columbia

The efficiency of a 4 inch hydrocyclone was studied using a suspension of fine silica at pulp. densities of up to 507o solids by weight. The variables manipulated were diameter of the vortex finder, flowrate, percent solids in the feed and cyclone length. Slurry temperature was also measured. All measurements were made with the spigot adjusted to give the same degree of roping at the underflow. The product size distributions were analysed using an electronic particle sizing instrument similar to the "Coulter Counter" but interfaced with a digital computer. An advantage of this method is the continuous curves produced (154 data points per run). Equations were developed by means of stepwise regression analyses to predict (I) separating size, (2) inlet pressure, (3) bypass ratio, (4) sharpness of classification, alpha, (5) zero classification size and (6) water recovery in the underflow, as a function of hydrocyclone variables including temperature of the feed slurry. Two forms of a roping constraint equation were obtained. One predicts the underflow percent solids at which roping occurs, whilst the other gives the spigot size required to avoid roping. The separating size was found to depend on several factors including the temperature of the feed slurry. Moreover, the sharpness of classification, alpha, was identified to be a variable parameter. This parameter was found to be dependent on variables such as vortex finder diameter and the volume recovery of slurry to the overflow. The variability of alpha has not been widely recognized. Acceptance of this variability concept offers hope that classification efficiencies may be improved by choosing the proper combination of variables in an operating environment. Interestingly, the zero classification size was judged to be a constant at the 0.05 level of significance. The bypass ratio depended primarily on the water split, as expected, but was also influenced by the cyclone feed percent solids. It is suggested that this particular study advances the understanding of sub-sieve sized particle behaviour in hydrocyclones fed with slurries containing a high proportion of solids.

Text

2010-02-19

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http://hdl.handle.net/2429/20519

Mining Engineering

University of British Columbia

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