Development of the selective hydrophobic coagulation process. Technical progess report for the eighth quarter, 1 July 1993--30 September 1993

Abstract

A novel technique for selectively coagulating and separating coal from dispersed mineral matter has been developed at Virginia Tech. The process, known as Selective Hydrophobic Coagulation (SHC), has been studied under the sponsorship of the U.S. Department of Energy since 1986. The SHC process differs from oil agglomeration, shear flocculation, polymer flocculation, and electrolytic coagulation processes in that it does not require reagents or additives to induce the formation of coagula. Often, simple pH control is all that is required to (i) induce the coagulation of coal particles, and (ii) effectively disperse particles of mineral matter. When the coal is superficially oxidized, a small dosage of reagents may be used to promote coagulation. During the past quarter, work was completed on the prediction of optimum conditions for the SHC process using the extended DLVO equation (Subtask 2.3). In addition, the evaluation of the lamella thickener for separating hydrophobic coagula from dispersed mineral matter was completed. Work is now underway to complete the evaluation of other separation devices including a vacuum filter, flotation column and centrifuge (Subtask 3.3).