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Abstract

The use of electrostatic demulsification methods to separate fine particulates of differing surface characteristics is disclosed. In one example, particles of hydrophobic coal and hydrophilic kaolin clay, each of nominal 3.5 micron mass mean particle diameter, were separated from a variety of stable water-in-oil emulsions. 50/50 blends of coal of 4% ash and kaolin clay of 86.5% ash were used in the experiments. A variety of oils, water concentrations, solids concentrations, and emulsifiers have been used in this work. Externally applied electrostatic fields up to 1.2 kV/cm were used. Greater than 90% rejection of kaolin particles into the separated water phase was achieved with virtually complete recovery of the coal particles uniformly suspended in the oil phase. Under conditions resulting in the most efficient separation, we have observed that the coalesced water phase appeared as intertwined cylindrical tubes extending between electrodes, as opposed to nonconnected and chained droplets which have been reported by others. The fine kaolin particulates were observed to be water-encased while most coal particles remained dispersed in the oil continuum.

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First Claim