Experimental Study on the Oxygen-Enriched Combustion Characteristics of CO in the Flue Gas from the Anode Furnace

Coal as reducing agent during the pyrometallurgical copper refinement in the anode furnace leads to high-concentration CO in the flue gas, severely hindering the resource recovery of SO2 from the flue gas. This problem may be resolved via installing a combustion chamber downstream, which introduces air to assist CO oxidation. However, the complex composition in anode furnace flue gas affects CO combustion reaction, and the flue gas temperature may decrease significantly during flowing to the combustion chamber, making CO combustion difficult. Additionally, the significant air leakage in anode furnace makes it difficult to determine the volume of flue gas, which hinders the calculation of oxygen agent amount needed in combustion chamber. In this study, an anode furnace with single production copper output of 160-ton class was selected, and its flue gas volume as well as the required air supply for complete CO combustion was calculated based on the CO concentration via adopting the elements conservation law. When CO accounts for 3-10% of total flue gas volume, the total flue gas flow rate ranges from 6800.3-7637.3 Nm³ during the reduction in the anode furnace, and the required air supply for CO burn off ranges from 545.1 m³ to 1617.9 m³. Based on the flue gas compo-sition and conditions at the combustion chamber, the influences of temperature, CO₂, and H₂O concentration on CO oxidation were systematically investigated via using a tube reactor experimental system. CO oxidation initiated at 500 °C and reached near-complete conversion (99.9%) at 800 °C. The addition of 5% H₂O notably enhanced the reaction, reducing the T50 (50% conversion temperature) from 675 °C to 650 °C. Conversely, a marked suppression was observed with 6.09% CO₂ at 650 °C, where the oxidation rate dropped sharply from 50.27% to 27.75%. A dedicated examination of O₂ then confirmed that increasing its concentration effectively enhances combustion completeness under the optimized conditions. At 650 °C, the CO oxidation rate increased from 24% to 56% as O₂ rose from 17.58% to 41%, whereas a further increase in O₂ to 51% suppressed the rate to 39%.