Feasibility of Hydrocyclones for Dredge Spoil

The purpose of this study was to experimentally determine the feasibility of using hydrocyclone separators for the concentration, clarification, and classification of a dredge spoil. Six dredge spoil samples (supplied by the United States Army Corps of Engineers), two clay slurries, and one sand were used to determine the effect of particle size, viscosity of the fluid, and inlet solids concentration on the effectiveness of 10-gpm hydrocyclones. While the clarification and concentration performance of the hydrocyclones was good on low solids content clay slurries, the performance ranged from below average to poor on the spoil samples. The poor capability of the separators to clarify and concentrate these spoils was due to a combination of high solids content, small particle sizes, and highly pseudoplastic behavior of the spoils. The high solids content affects clarification more than it does concentration, and thus, hydrocyclones may be reasonable effective concentrators for the low solids content spoils. Meanwhile, the hydrocyclone proved very successful at recovering sand from the full range of spoils.