The Batch Extraction Unit (BEU) has been in use since the 1980's for studying the extraction of bitumen from oil sands under selected conditions. The disadvantages of BEU technique are that it is a tedious, time-consuming method and does not always correlate well with field conditions.
The present study is an investigation of an alternative method for estimating bitumen recovery, based on visualization of oil sand slurry undergoing digestion. A Couette flow type device, which consists of an inner cylinder rotating in an outer cylindrical vessel, is used for the study. The annular space between the inner rotating cylinder and the outer vessel is loaded with known amounts of oil sand and water. Air is bubbled through the oil sand slurry, from the bottom, while the oil sand slurry is subjected to controlled chemical conditions and shear environment. Under these controlled conditions, images of the slurry are captured at various time intervals and then analyzed using an image analysis software, Sigma Scan Pro. The software selects black areas based on the gray scale intensities of the area in view. The variation of the black area with time is used as a measure of bitumen recovery from oil sands. The technique provides quick estimates of "bitumen recovery" with ease, as a function of time enabling kinetic studies of bitumen recovery, which are otherwise difficult to carry out using conventional methods. The experimental set-up used offers great flexibility in selecting conditions for the digestion of oil sands, i.e. the air flow rate, temperature, chemical conditions and shear rate.