Silicon is mostly produced in rotating submerged arc furnaces with continuous tapping of metal. The burden is often dense due to condensates. Thus, furnace gas does not escape easily to the top of the burden and some gas escapes through the tap-hole. This can cause a hazardous flame jet out of the tap-hole which poses an HES threat to operators. A mathematical CFD model has been developed to study the flow of gas and metal in the furnace through the tap-hole. A modelling challenge is to account for the continuous tapping and the rotating furnace. These aspects differ from earlier CFD studies applied to furnace tapping. Results indicate the difference in tapping behaviour as the burden permeability varies and as the position of the tap-hole varies due to the rotation.