Multiphase reactors are abundantly used in many industries. Among them, few reactors deal with four phases called gas-liquid-liquid-solid systems, which receive less attention due to their complex situation. Numerical study of such complex systems is not easy and requires large computational effort. In this study, a discrete-continuous numerical model known as the eXtended discrete element method (XDEM) is proposed to investigate the hydrodynamic behaviour of fluid phases passing through the packed bed of solid particles. This model is applied to the dripping zone of a blast furnace. In this zone, two distinct liquid phases, namely liquid iron and slag, flow through a pile of coke particles while exchanging momentum. In this work, besides the solid-fluid and gas-liquid interactions, the liquid-liquid interactions are also studied and the phases' mutual effects are discussed. In addition, a sensitivity study on the slag viscosity is performed, which shows the importance of liquid phase properties on the system behaviour. The results evaluation shows that the liquid iron accelerates the downward flow of the slag and the slag decelerates the downward flow of the liquid iron phase due to the resistance force caused by their relative velocity.