Conventional (two-product) hydrocyclones have a wide range of applications in most of the mineral plants. The design of various hydrocyclones differs depending on the application but the most common one is the cylindrical-conical shape with variations in its cylindrical length and cone angle. In this paper, the design and operation of a three-product hydrocyclone which generates two-underflows and one-overflow is described. This type of the three-product hydrocyclone was tested successfully in the solid-liquid separation processes. The influence of opening diameters; overflow diameter (d(o)), middling flow diameter (d(m)), and underflow diameter (d(u)) on the solid and water recovery in the three products was also investigated and general prediction equations were estimated. Some potential applications of the new type three-product hydrocyclone were studied. (c) 2008 Elsevier B.V. All rights reserved.