SEPARATING SMALL PARTICLES FROM LIQUIDS WITH THE HYDROCYCLONE. PART III. EFFECTS OF MAJOR OPERATING VARIABLES

Commission Research Establishment, Lucas Heights, New For cyclone configurations producing flow ratios of 0.1 or less, the concentration efficiency increases as the feed concentration increases and then levels out at a concentration defined as the critical feed concentration. The clarification efficiency is independent of feed concentration up to concentrations slightly less than the critical feed concentration and then decreases. Both efficiencies increase logarithmically with flow rate. For a cyclone configuration of feed diameter (D/sub i/) = 0.082 in., overflow diameter (D/sub o/) = 0.098 in., and underflow diameter D/sub u/) = 0.037 in., correlations are proposed for the critical feed concentration in terms of the effective density ratio and concentration and clarification efficiencies in terms of the feed concentration, feed flow rate, and the Rosin-RammlerBennett size distribution constant of the solid. For cyclone configurations producing flow ratios from 0.2 to 0.5, the concentration efficiency is of minor importance. The clarification efficiency is found to be practically independent of concentration and also of flow rate except for materials with large distribution constants. Correlations are proposed for the clarification efficiency for a cyclone configuration of D/sub i/ = 0.055 in., D/sub o/= 0.079 in., D/sub u/= 0.058 in. Optimum results may bemore » obtained for a given suspension by choosing suitable flow ratios and hence cyclone configurations for each stage of a multi-stage unit. However, for maximum flexibility in handling changes in operating variables, a unit combining constant cyclone configuration with underflow throttling would be preferable. The concentration and clarification efficiencies are not greatly affected by the average particle size or size distribution of the solid but the degree of classification obtained is markedly affected by both. (auth)« less