One common approach for improving the efficiency of single-screw extruders is to increase screw speed. At higher screw speeds, the solids-conveying zone in single-screw extruders becomes more important – especially if the hopper opening is not designed properly, as this can lead to an insufficiently filled screw channel. Consequently, the total extruder throughput can be limited by the solids-conveying throughput if the latter is smaller than the theoretically conveyable melt throughput. At high screw speeds, the flow of pellets is additionally influenced by a so-called circulation flow within the feed opening. To investigate such effects, the Discrete Element Method (DEM) is becoming increasingly important. New research deals with the simulation of pressure buildup in high-speed single-screw extrusion. To obtain useable results, it is essential to use suitable simulation parameters. These can be obtained by validating compression simulations on the one hand and solid conveying simulations on the other. Compression tests and their simulation have been published in former articles. The goal of this contribution is to describe a method of simulating solid conveying processes in single screw extruders also realizing a definite back pressure which leads to a resulting pressure buildup in the screw channel. Material parameters are presented as well as some details concerning the used contact model and the simulation tool EDEM. Additionally, a test setup is presented which is used to validate the solids conveying simulations. Results are shown for both, simulations and experimental tests. Comparing the results from simulations and measurements shows acceptable conformity. Such simulations and experimental tests are important to better understand the buildup of pressure in high-speed single-screw extruders.