This device continuously dewaters phosphatic clay suspensions through electrokinetics. A typical Florida phosphate mining operation produces more than 100,000 gallons per minute of phosphatic clay, which is pumped into large ponds known as clay settling areas, or CSAs. The current separation method of this mining waste product uses gravity settling and vast amounts of land. More than 150 squre miles of CSAs currently cover central Florida, representing 30 percent of the mined land. Consolidation of the clay can take 25 years to complete and still leaves clay too soft to build upon. The need both to reduce the land area required for clay suspension storage and to reduce the water usage in the mining operations has led researchers to search for an inexpensive method that can enhance the process of dewatering.
Researchers at the University of Florida have created a device that effectively separates water from phosophate mine clay solids and by applying an electric field. This design creates a 10-fold reduction in the electrode area, as compared to previous designs, which reduces efficiency and the cost to perform the continuous electrokinetic dewatering process. By utilizing electrical fields, this system also eliminates the need for chemical additives to aid the separation process, unlike its competitors.
An electrokinetic dewatering system for extracting water from phosphatic clay suspensions.
This device continually dewaters phosphatic clay using an electrokinetic method. It feeds phosphatic clay suspensions between two conveyor belts and allows the clay to come into contact with electrodes that apply an electric field. As it passes the electrodes, water drains freely away from the phosphatic clay solids and forms a dewatered cake solid, or thickened layer of clay, with a solids content of 31-38 weight percent, surpassing available dewatering methods. Additionally, this system allows for a 10-fold reduction in the required electrode area compared to a previous design, improving clay-water separation efficiency and reducing the operational cost, making this the ideal system for dewatering of phosphate mine tailings.
