The imaging of filter cakes through electrical impedance tomography

An experimental rig capable of automatically sequencing and collecting data from a dead-end pressure filter is described. The computer-controlled apparatus uses electrical impedance measurements in multiple vertical scanning planes to determine the status of a filter cake during either the cake formation, gas dewatering or displacement washing phases of a filter cycle. The data acquired are displayed in real time during a test in conjunction with liquor flow rates. Initial results from an experimental programme are presented, which show the filtration and dewatering characteristics of aqueous-based calcium, carbonate suspensions. The importance of data acquisition and system control are discussed, and an outline of future developments is given.