A methodology has been developed to determine the optimal size and lifetime of pipelines transporting multi-sized solideliquid mixtures. The methodology includes a model for prediction of various life-cycle costs for the flow of multi-sized particulate solideliquid mixtures in a pipeline. The particle size distribution
effects have been incorporated in the analysis by the weighted mean diameter. The methodology
provides a closed form solution to predict the optimal pipe diameter corresponding to the least
total cost for given solid characteristics. Such solutions are obtained for different life-cycle costs, of which the one associated with minimum annual total cost provides the lifetime. The developed methodology has been used to obtain the optimal diameter of a pipeline for a practical case. The parametric study reveals the interrelationship among various flow parameters including the optimal pipe diameter, the
corresponding minimum total cost and the particle size.