Recent Enhancements In Mined Oil Sands Bitumen Extraction Technology

Abstract

Abstract The results of a study to evaluate promising alternatives to the Hot Water Extraction Process for extraction of bitumen from mined oil sands are reviewed and reassessed in light of recent developments in bitumen extraction technology. The original study, completed in 1983, identified and analyzed, in detail, promising extraction processes. Process development has continued (in particular with respect to the commercialized Syncrude and the Taciuk direct retorting processes) and is assessed both on a technical and economic basis, in a manner similar to that used in the original study. It is found that the Syncrude developments increase bitumen recovery and energy efficiency and reduce production costs co levels comparable to other promising aqueous extraction processes. Concerns with tailings accumulation of the process remain unresolved. These accumulations represent major environmental and resource recovery concerns. A high priority should be placed on developing a suitable commercial process to overcome these concerns. It is concluded that if Syncrude's expectations on improved bitumen recovery are realized then, due to the diminished concern with this factor, future commercial technology development will follow two routes:modification or improvements to the existing technology, particularly in the area of tailings handling, andnew technologies such as direct retorting or solvent extraction which have the potential to achieve significant benefits that could not be achieved by development to the existing technology in a similar or shorter time frame. Introduction In February, 1984, a study, commissioned by the Alberta Energy Resources Conservation Board (ERCB), was published describing the evaluation of alternative bitumen extraction processes(1). The study evaluated the processes, compared to a base case Hot Water Extraction Process (HWEP), derived from published information on the present commercial Athabasca oil sands mining operations. Syncrude Canada Ltd. has recently described(2) modifications to the bitumen extraction and upgrading units at its Fort McMurray plant. These modifications are expected to increase bitumen and diluents naphtha recoveries from the plant. The objective of this paper is to update the information presented in the original study, especially in relation to the proposed Syncrude modifications. Firstly, however, a brief overview of bitumen extraction technology is given. Overview of Bitumen Extraction Technology The processes for the extraction of bitumen from mined oil sands can be broadly classified, depending upon extraction medium and mechanical system used, as follows:Hot Water ExtractionModified Hot Water ExtractionDirect RetortingSolvent ExtractionOther Extraction Methods. The Hot Water Extraction Process (HWEP) is the only commercially proven process for the extraction of bitumen from mined oil sands. Oil sands are conveyed to the extraction plant and mixed with hot water, steam and caustic soda, in rotating tumblers to condition the ore. Bitumen is extracted as a froth in primary and secondary separators. The extracted bitumen is diluted with naphtha and undergoes two stages of centrifuging, in a froth treatment plant, to remove solids and water before being fed to the upgrading unit.