The behaviour of the particulate phase in a turbulent gas-solid channel flow is investigated by means of an improved Lagrangian stochastic model combined with realistic treatment of saltation phenomena using an irregular bouncing model for particle-wall collisions. Such particle-wall interaction mechanisms, which are difficult to include in two-fluid (Eulerian-Eulerian) models, may be accurately described by means of the Eulerian-Lagrangian approach. In that sense the present study is a preliminary step towards improvement of the formulation of wall boundary conditions needed in twofluid models. Particles are numerically tracked by predicting the instantaneous fluid velocity at the discrete particle location using a modified Langevin model, which takes the anisotropy and the non homogeneous character of the turbulence into account. Comparisons with available experimental data are provided, and examples illustrating the effects of the collision parameters upon the particle mean and r.m.s. velocities, kinetic stresses and concentration distribution in channel flows are given. The effect of irregular bouncing upon the relationships between various particle velocity correlations at the wall is examined and discussed with relevance to boundary conditions used in Eulerian two-fluid models.