MULTISTAGE WIDE-ANGLE HYDROCYCLONE CIRCUITS FOR REMOVING FINE, HIGH-DENSITY PARTICLES FROM A LOW-DENSITY SOIL MATRIX

Simulations were performed for various hydrocyclone staging arrangemen ts using experimental results from single-stage wide-angle hydrocyclon e separations when processing fine (-150 mu m) particles in a 25 mm di ameter hydrocyclone. Mixtures of line quartz and magnetite or ferrosil icon of similar size ranges were used to represent low density (e.g., soil) and high density (e.g., heavy metal contaminant) particles, resp ectively. The staging arrangements included re-treating the overflow a nd/or underflow streams in both once-through and recirculating circuit s. The results indicated that heavy metal recoveries greater than 95% with soil rejections over 90% could be obtained for the ferrosilicon/q uartz system using a three-stage circuit. Lower metal recoveries were obtained when processing the lower density magnetite.