To efficiently model wet grinding in tumbling mills is a difficult task. Because of the complex behaviour of the pulp with free surfaces and large deformations, the difficulty is usually that the method to represent and reproduce its movements is demanding and time consuming. In this work, an investigation of the possibility to efficiently model and simulate the whole mill body, including the pulp and the charge, and its simultaneous interactions with both the charge and the mill structure is presented. This is done by the ICFD method, which is a Lagrange based method that gives the opportunity to efficiently model the pulp free surface flow, and its interaction with grinding balls and mill structure. Validation is done against experimentally measured driving torque signatures from an instrumented small-scale batch ball mill equipped with an accurate torque meter, and charge movements captured from high-speed video. Numerical results are in good agreement with experimental torque measurements.