There have been numerous correlations proposed for determining a solids friction factor (lambda(s)) for fully suspended (dilute phase) pneumatic conveying. Currently, there are no equivalent correlations that predict lambda(s) in nonsuspension dense-phase flows. In dense-phase conveying there are two basic modes of flow: plug/slug flow, which is predominantly based on granular products, and fluidized dense-phase flow, which is more suited to fine powders exhibiting good air retention capabilities. In plug/slug type flow, the stresses between the moving plug of material and the pipe wall dominate the solid-phase frictional losses. In fluidized dense-phase flow the frictional losses are characterized as a mixture of particle-wall and particle-particle losses but are heavily influenced by the gas-solid interactions. In this paper, a series of calculations were Performed on experimental data ill order to estimate lambda(s) for four types of material conveyed in the fluidized dense-phase flow regime. The solids frictional factors were found to be relatively independent of particle propel-ties for varying air and solid mass flow rates and pressure drops.. The resultant pressure drop from the empirical model showed good agreement with the experimental data.