A model cascade is usually created before constructing a practical isotope separation cascade as the target for approximating a practical cascade. The Q-cascade is a widely used model cascade for continuous profiles in separating multi-component isotope mixtures. The optimization of a Q-cascade with specified concentrations for a target component in the product and waste flows can be conveniently performed by adjusting the mass number (V) of a virtual component. In previous studies, the It parameter was treated as identical throughout the entire cascade. This paper proposes further optimization of a Q-cascade by splitting the cascade into segments and allowing each segment to take a different value for M.. An example is presented for separating Cd isotopes; the numerical results demonstrated that segmented Q-cascades achieved better separation performance than traditional Q-cascades. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.