The efficiency of thermal electro-osmosis method in dewatering of alumina tailings

Electro-osmosis is one of the most important methods for water separation from two-phased materials. This study investigated the effects of temperature, voltage, and initial moisture on the electro-osmosis process for the tailing sludge’s dewatering. The material is red mud from alumina mine tailing. Since an electrochemical cell is capable of regulating temperature and voltage, the effects of temperature and voltage variations on the electric current and dewatering process were studied. Based on the results, an increase in voltage at low temperatures (25°C) doubled the electric current while it increased about four times at higher temperatures (35°C). The use of high voltages always increased the final amount of collected water. Although the initial rate of dewatering increased with temperature, the final amount of collected water decreased in high temperatures due to the induced Joule heating effects. Moreover, the increase in temperature and voltage led to an increase in electro-osmotic permeability. The maximum electro-osmosis permeability occurred at a temperature of 45°C and voltage of 21V, where the highest rate of dewatering and lowest time of process also occurred. The amount of collected water in samples with more initial moisture content was larger. The largest reduction of moisture content occurred near the anode, then around the cathode, and finally in the middle of the samples.