Abstract: This invention relates to a system for separating a multiphase liquid mixture into a plurality of streams. The invention has particular utility in the oil industry where particulate solids are produced with an oil/water mixture. Preferably, the mixture is first cyclonically separated to remove particulate solids from the oil and water. Then the mixture is delivered to a liquid/liquid hydrocyclone where a substantial portion of the oil is separated from the remaining mixture which now primarily comprises water. The pressure of the remaining mixture is elevated such as by a pump and is then subjected to a further cyclonic separation step to remove any remaining fine solids in the mixture.

Abstract: Cyclone separator having an elongate tapered separating chamber (25) with an axial overflow outlet (34) at the larger diameter end (10a) and an underflow outlet (23) at the smaller diameter end (10b). Inlet to the separating chamber is provided via an axially extending duct (70) which joins the separating chamber at its larger diameter end. The duct is of annular configuration and has a helical flight (90) positioned therewithin.