Extraction of bitumen from the oil sands of Alberta with hot water produces a tailing sludge which is very difficult to filter or dewater. The exceptional stability of the sludge is due to the presence of clays, chiefly kaolinite and montmorillonite.
Methods of flocculating this sludge have been investigated. Flocculation by an anionic polyacrylamide after pretreatment with optimum concentration of Mg2+ or Ca2+ ions gave best results.
Dewatering of the flocculated sludge by drainage on a sand bed and on a wire mesh has been investigated. Compact flocs carrying < 40% moisture could be obtained.