Bench-Scale Bitumen Release Analysis (BRA)
Authors: Wang N. , Salama A.I.A. , Mikhail M.W. 
Published: July 2010

Introduction

At present, the oil sands industry is utilizing the Syncrude bench-scale procedure for assessing bitumen extraction in oil sands(1). However, this procedure was designed based on Clark hot water bitumen extraction technology and does not address the degree of bitumen extraction utilizing intensive extraction or the quality of the froth. Aflowsheet of Syncrude procedure is shown in Figure 1. An extension of the Syncrude procedure was developed at CANMET Energy Technology Centre, Devon (CETC-Devon) whereby successive hot water bitumen extractions are carried out on the ore sample and successive tails. The successive froths are collected during the test to quantify the maximum bitumen recovery, without further treatment(2). A flowsheet of CETC-Devon procedure is shown in Figure 1. Such a procedure does not address the quality of froth because of the entrainment of liberated mineral matter into the froth. Furthermore, it is known that bitumen release is greatly influenced by additive additions, pulp density, and pH. Consequently, a bench-scale procedure is needed to assess the degree of bitumen release and froth quality under intensive extraction.

Dell developed a release analysis procedure to evaluate the flotability of fine coals(3). In this procedure, the ore samples are initially separated into floatable and non-floatable components by repeated stages of flotation. The floatable material is then separated into components having different floatabilities. It is reported that the Dell release analysis procedure produces the optimal separation performance achievable from the use of a froth flotation process for cleaning fine coal(4, 5).

In this paper, a bench-scale procedure designated bitumen release analysis (BRA) utilizing a combination of the Dell release analysis and the Syncrude bitumen extraction procedure is presented.

BRA Flowsheet

At present, bench-scale hot water bitumen extraction is carried out by following the Lab Scale Hot Water Extraction of Oil Sand procedure detailed in Syncrude Analytical Methods for Oil Sand and Bitumen Processing(1). A 1.6 L extraction cell identical to the one used in Syncrude procedure and later adopted by CETC-Devon is used in the BRA procedure.

BRA tests are carried out by following the Dell procedure with some modifications for treating oil sand materials. A detailed schematic flowsheet of the BRA procedure is shown in Figure 2, where residual (R), designates material left in the cell for further treatment. The BRA procedure involves separation of the nonfloatable material from the floatable material, and consists of a number of flotation stages to ensure that all particles with a tendency to float are collected into the froth and all other particles report to tailings.

BRA Procedure

Operating Parameters

Preliminary tests were conducted using a 1.0 L glass beaker and observations of the behaviour of bitumen and tailings during extraction were used to determine the best operating conditions to be used in the batch test. The same impeller was used in both the preliminary and release analysis tests. Therefore, the experimental results obtained using the 1.0 L glass beaker should be comparable with those obtained using the 1.6 L extraction cell.