Blasting Method for Improving the Secondary Combustion Efficiency in the Romelt Process Using CFD Analysis

The Romelt process is called liquid-phase smelting reduction process because in the metallurgical processes the reaction of coal and iron occurs in the liquid slag layer, which is boiling vigorously by oxygen-enriched air flow blown into the liquid slag. The bath of the furnace is charged with coal and iron ore, and an oxygen nozzle for secondary combustion is installed on both sides of the bath cavity to burn out the CO and H<sub>2</sub> gases generated in the bath. CO and H<sub>2</sub>, rising from the boiling slag bath, are completely burned by oxygen blown into the secondary nozzle in the combustion chamber. The heat from this combustion reaction plays an important role in the Romelt process. 60-80% of the secondary combustion heat is transferred to the bath and becomes the heat source of the main process. At present, the Romelt process has a high CO content in the exhaust gas due to the low efficiency of combustion by oxygen blown into secondary nozzle and low oxidation of CO. This paper analyses the reason of the low efficiency of combustion by oxygen blown into conventional secondary nozzle using CFD, and based on it, suggests the blasting method to increase the secondary combustion efficiency by oxygen blown into the upper tuyere of the Romelt furnace. To improve the secondary combustion efficiency, a new type of catalyst for enhancing the oxidation of CO was investigated and more than 90% of efficiency of secondary combustion was achieved. At this time, oxygen concentration should be at least 95%.