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A multiphase model for the flow of dense, noncolloidal, settling slurries through horizontal pipelines, and an associated Galerkin-finite element numerical scheme to carry out computer simulations based on the model, were developed. The principal elements of the model are: equations for estimation of the velocity distributions for each component: and those for the concentration distributions. In the former, which are derived from the local volume-averaged, time-smoothed conservation of mass and momentum equations, the total stress is comprised of components to account for interparticle and particle-boundary as well as viscous and turbulent interactions. The governing equations for the concentration distributions are derived similarly from the convective diffusion equation, with the eddy diffusivity modified to account for the presence of the solid particles. Numerical simulations and detailed comparisons with experiment for the flow of gypsum, coal, crushed glass, sand and gravel, covering particle sizes from 38.3 pm to 13,000 pm, and pipe diameters from 4 cm to 49.5 cm, were carried out. The agreement between model prediction and experiment is excellent. Previous Work and Background Datalowed one of these three major approaches:Studies concerned with solid-liquid mixture flows have fol-1) The empirical approach 2) The rheologically-based continuum approach 3) The multiphase flow modeling approach The empirical correlation approach seems to have received the most attention, certainly early on, almost surely as a concession to the mathematical complexity of slurry flows. Because of its long history, a large body of empirical studies dealing with slurry transport has accumulated. Correlations for prediction of