The theory of inclined plate separator (IPS) operation is studied from the standpoint of the possibilities for the use of reagents to promote improved dewatering and demineralisation of oil sand froth. The potential for the use of CFD methods to determine the efficacy of these chemicals is also reviewed. For most purposes chemical additions are added in experimental programs as a means of determining the asymptotic limits for product quality figures of merit achievable without the use of chemicals. This is because volumetric flows in oil sand processing are so great that the addition of chemicals is not encouraged due to the enormous cost factor that becomes inevitable in most cases. Therefore, the focus of this paper is on the overall strategy of avoidance of the use of artificial chemical process aids, in other words reagents, but depending more upon natural process aids that occur in the oil sand or in the diluents and solvents used to extract hydrocarbon. (C) 2004 Elsevier Ltd. All rights reserved.