ON BITUMEN LIBERATION FROM OIL SANDS

Laboratory experiments were performed to investigate the effect of pH on (a) bitumen film thinning and film rupture process (b) bitumen/wate r contact line displacement and (c) the static contact angle of bitume n on a glass surface in the presence of an aqueous medium. A coated bi tumen film on a glass surface was found to thin down and rupture spont aneously when a few drops of water having a pH of 11 was placed on it. In another experiment, a bitumen coated glass plate was submerged in water. The contact line of an initially circular bitumen film on the g lass surface displaced in the inward direction to take the shape of a droplet. Measurement of the dynamic contact angle of bitumen with time showed that the bitumen/water contact line displacement was faster at a pH of 3 than at a pH of 11, However, the static contact angle of bi tumen on the glass surface was found to be large at the high pH of 11, a condition conducive to easy detachment of bitumen droplet from the glass surface. The above observations suggest that a pH cycle might be desirable in bitumen liberation from oil sands.