Abstract: Particle-wall collisions widely exist in bulk solids transportation. Investigations on particle-wall collisions are helpful to optimize transporting system, decrease product attrition or improve transportation economy. Collisions between a single coarse particle (6 mm in diameter) and a wall were investigated by Hertz-Mindlin no-slip contact model based on discrete element method (DEM). Effects of impact velocity, impact angle and shear modulus on contact processes and maximum normal contact forces were studied. Results show that the normal contact process described by Hertz-Mindlin no-slip contact model shows self-similarity feature, and the ratio of unloading to loading duration in normal direction keeps as a certain value. The numerical contact durations agree well with the predictions by the correlation of Thornton et al. The impact velocity and impact angle show obvious effects on maximum contact forces. The normal maximum contact force increases almost linearly with normal impact velocity. For the certain impact velocity of 2 m/s, the normal maximum contact force decreases with the increase of impact angle. The shear modulus is a key factor to normal contact force, which suggests that speeding up DEM simulation by decreasing shear modulus should be avoided when particle attrition and/or breakage are in consideration. The results in the present study are important for investigation of particle attrition and/or breakage, as well as optimization of absorber sphere pneumatic conveying process in high temperature gas-cooled reactor.