Technology of the recovery of values from tar sands

There are two basic approaches to recovering bitumen. The tar sand may be mined and transported to a process plant where the bitumen is extracted and the sand is discharged. Alternatively the separation of bitumen from sand may be accomplished without ever moving the sand, that is, in situ. In situ processes have a great deal in common with secondary recovery of conventional crude oil. Each of the recovery processes which has been described in the open technical literature is discussed below. A number of additional processes, presently of minor importance, are described in patents1. To understand the relative merits, of course, the various processes must be compared. Since the scale of operations described varies from laboratory batch experiments to a 10 ton/hr pilot plant, these comparisons must be made with the greatest care. The term yield or bitumen recovery is subject to so many definitions and possible methods of calculation that comparisons are possibly meaningless. Unfortunately, practically no economic data are available. Despite these shortcomings, process flow sheets may readily be compared. Fundamental process requirements, such as heat, can also be calculated and reliably compared.