The hydrocarbon cyclone is capable of achieving a ternary split in a range of froth treatment processes in oil sand mining and extraction. A ternary split is the maximization of water and fines rejection, while producing a high hydrocarbon recovery to the overflow and a coarse rejection to underflow that approaches 100%. The hydrocarbon cyclone takes advantage of the water-wet characteristic of oil sands in a diluted bitumen environment. In the case, of purely bituminous streams, bitumen and fines will follow water to the overflow in a hydrocyclone, but in the Athabasca oil sand deposits the sand and clay are profoundly hydrophilic and the presence of diluent alters the slurry theology. This paper explores the phenomenology of the hydrocarbon cyclone illustrating its application to several oil sand unit processes. The paper identifies the unique features of oil sands and describes the influence of oil sand theology on the boundary conditions and the equations of motion for the advanced use of computational fluid dynamics (CFD). (C) 2004 Elsevier Ltd. All rights reserved.