HOT-WATER EXTRACTION PROCESS MECHANISM USING MODEL OIL SANDS

A mechanism for the hot water extraction process is proposed based on new results from extraction tests using model oil sand. II was found t hat bitumen can be completely liberated from the oil sand matrix and f orms aerated droplets during slurrying with water without adding proce ss aids. However, the aerated bitumen droplets were unable to float du e to the attachment of sand particles on the surface of the bitumen dr oplets. When sodium hydroxide (NaOH) was added, the sand particles wer e released from the bitumen droplets, resulting in bitumen recovery. H igh recoveries were obtained by adding NaOH to either connate water or slurry water. Bitumen loss was attributed to incomplete bitumen/sand separation and oil-in-water (o/w) emulsification resulting from defici ency and overdose of NaOH, respectively. The use of commercial sodium naphthenate or sodium laurate as process aids had no effect. The size of the aerated bitumen droplets increased as the oil content and/or th e size of the sand particles increased. The bitumen recovery and the s ize of the aerated bitumen droplets increased when the sand was pretre ated with NaOH. Liberation of bitumen from the oil-wet model oil sand could be achieved by using excess NaOH, but the liberated bitumen was non-recoverable due to emulsification. Increasing the amount of slurry water had a detrimental effect on aeration.