Pressure-swirl nozzles producing hollow-cone sprays are widely used in many engineering applications, but the induced high-speed stream along the centreline of the spray cone was ignored in designing spray chambers. The high-speed stream influences the flow field especially in minimized spray chambers, but it is difficult to characterize experimentally. Hence, computational fluid dynamics was applied to investigate the multi-phase flow interactions inside a novel spray pyrolysis furnace for liquid ore exploitation. The mass flow rate distribution of the co-axial swirling stratified flow inside the furnace, the gas-solid separation efficiency, particle size distribution, and residence time were investigated under different positions and directions of the hollow-cone spray. The results proved that different spray operations would cause variation in the air mass flow rate distribution and gas-solid separation efficiency, which should be paid attention to in the design of process intensification. The distribution of particles sized from 30 to 40m were most sensitive under different flow rates. The recommended operating conditions of the spray pyrolysis process were confirmed as the inlet velocity of 5m/s and downward spray from the top of the furnace chamber.