This paper results from ongoing research into the modelling of solids friction for fluidized dense-phase pneumatic transport of fine powders. Energy loss due to particle to particle and particle to wall collisions have been modelled. A new model for particle velocity has been introduced using numerical analysis and variable fluidized bulk density, which has shown that slip velocity decreases with an increase in the mass flow rate of air and dimensionless length. A new modified two-layer model for solids friction factor has been developed by introducing the collision effect and particle velocity model in the model of solids friction. The results of scale-up validation in larger and longer pipelines for four different products have shown that for the majority of the cases, the new model for solids friction factor has resulted in better predictions in dense-phase flow conditions compared to the predictions obtained by an existing two-layer model. (C) 2019 Elsevier B.V. All rights reserved.