Semi-Continuous Electrokinetic Dewatering of Phosphatic Clay Suspensions

A semi-continuous electrokinetic dewatering process, representing an intermediate step in development of a technology for continuous electrokinetic dewatering of phosphatic clay suspensions, was designed and evaluated through measurement of supernatant turbidity, pH, and changes in solids content. The influence of feed flow rate, electric field, and electrode separation was evaluated. The results showed that low-turbidity water can be separated from a clay solids suspension by a combination of electrokinetic dewatering and free settling. This work also suggests that separation can be enhanced at larger electric fields and that optimized separation may be achieved at a residence time of 11 h for this specific configuration. The energy requirement for this operation was shown to be consistent with previously published results for batch operation. The results provide guidance for the on-going development of a device for fully-continuous electrokinetic dewatering of phosphatic clay suspensions.