ABSTRACT The flue gas temperature of the Smelting Reduction Vessel (SRV) in the HIsmelt process is high while the temperature of the molten iron is low. Therefore, the heat transfer efficiency between the upper and lower regions in the SRV needs to be further improved. The fluid flow and heat transfer characteristics inside the SRV were studied to derive the mass fraction, temperature distribution, and gas motion. The error between the simulated and measured values remained stable within 5%. The gas in the centre of the SRV shows a high-speed vortex flow. The combustion reaction mainly occurs in the centre of the furnace. Since the heat transfer in the furnace is mainly influenced by the gas flow, the high-temperature zone shows a U-shaped distribution and is mainly around the centre of the region, the oxygen lance outlet, and the furnace wall.