An Innovative Bitumen Extraction Process for Oil Sands: Sand Reduction Technology (SRT) and Bitumen Concentration

Abstract

Abstract In 1991, Canadian Occidental undertook the development of a new process designed for efficient extraction of bitumen from oil sands which would be suitable for employment at remote sites. The new process, Sand Reduction Technology (SRT), is based on the separation of solids from an oil sand slurryin a system of hydrocyclones. The sand and clay in the slurry exit as a concentrated tails stream containing 70 to 75 percent solids. The remaining bitumen, water, and fine solids form an overhead stream containing 5 to 15percent bitumen. The objective of this new program was to test process concepts for efficient removal of water from this stream to produce a concentratedbitumen product stream containing 40 to 75 percent bitumen. Following a series of laboratory investigations, a small scale processdevelopment unit (PDU) was constructed in Canadian Occidental's laboratory in Tulsa to test the bitumen concentration process. The PDU was sized to feed 10Ibs/min of oil sands to a slurry preparation unit which consisted of a heatedtumbler. The slurry was screened to remove oversize solids and unconditioned oil sands and was then pumped to a one-inch hydrocyclone for separation of most of the slurry solids. The overhead stream from the hydrocyclone was tested in several process options to concentrate the contained bitumen, which averaged about 8 percent in this stream. Oil sands feed for this project was obtained from Syncrude Canada Ltd. and consisted of two grades described as "typicalgrade" and "low grade". Twenty-two PDU runs were made from November 1993 through June 1994. The operating plan for each run included a start-up period in which process conditions were established, followed by a one-hour material balance period. Two basic bitumen concentration concepts were evaluated, with several variations of each. The first process concept was based on the flotation of bitumen from the cyclone overhead stream. A four-cell Denver flotation unit was employed for this phase of the project, which included eight PDU runs. Good bitumen recovery was achieved in the flotation tests with up to 99 percent retention of bitumen in this part of the process. The bitumen was also concentrated, with bitumen concentration in the flotation froth averaging greater than 40 percent during optimal run periods.