Whole oil sands tailings resulting from water-based bitumen extraction processes can be co-flocculated, after treatment with slaked lime, with low dosages of a high molecular weight anionic polyacrylamide. The resulting composite sand-clay particles settle and dewater rapidly to a stackable product that can be hand-squeezed to 40–83 wt% solids. The final solids content depends on the initial bitumen extraction process used. The procedure is particularly appropriate for use with the alkali recycle process, in which bitumen is extracted from oil sand by flotation after conditioning with dilute alkali at ambient temperatures. Treatment of the resulting tailings with lime is the key step that releases alkali, by ion-exchange mechanisms, into the recyclable process water. This step is the first in the co-flocculation sequence