Flat ceramic membranes, prized for their corrosion resistance, abrasion resistance, and substantial processing capacity, find extensive applications in the filtration and separation processes of metal and non-metal pulp, such as iron ore, copper ore, and phosphate ore. In pursuit of a comprehensive understanding of the intricate internal flow dynamics inherent to flat ceramic membranes during the phosphorus concentrate separation process, this study aims to meticulously scrutinize the intricate nuances of flow field characteristics. In order to refine and optimize various parameters encompassing process intricacies, membrane architecture intricacies, and strategies for mitigating membrane fouling phenomena, a structural model for flat ceramic membranes is set up. Experimental and computational fluid dynamics (CFD) analyses are employed to validate the reliability of the porous media model in simulation. Subsequently, gas-liquid multiphase flow model and realistic gas model are integrated to investigate the dynamic variations in internal pressure and flow rate during the filtration of water through ceramic membranes. Additionally, the impact of air ingress, operating pressure and slurry concentration on the filtration process are analysed. Simulation results indicate that the entry of air has the most significant influence on vacuum degree when the operating pressure is set at -0.08 MPa. Transient simulations unveil the entire process dynamics of ceramic membrane filtration, from initial air evacuation to stabilized flow, revealing the first 3 seconds as the high-efficiency filtration interval. Subsequently, the flow rate decreases and stabilizes, with the stabilized flow rate contingent upon the outlet operating pressure. The difference in cumulative filtration flow rates between operating pressures of -0.06 and -0.08 MPa within 5 seconds is minimal. The research outcomes provide valuable theoretical guidance for determining the most suitable filtration durations and pressure settings tailored to diverse process specifications, as well as contributing to the enhancement of production efficiency and the reduction of energy consumption.