Optimizing the Nozzle Structure to Increase the Methane Utilization Efficiency for Copper Melt Refining: Water Model Experiments and Numerical Simulations

In modern copper smelting plants, natural gas (mainly CH₄) is blown into the copper melt to increase the copper purity from 98.5 to 99.5%, naming the pyro-refining process which guarantees the smooth operation of the subsequent electrorefining process. However, the low-density CH₄ gas tends to float upward swiftly to the upper surface of the melt, leading to very low utilization efficiency. Herein, a nozzle with honeycomb-like holes on the cross section is designed for injecting CH₄ gas, which contributes to prolonged residence time of the CH₄ bubbles in the melt, thus enabling deeper reaction. The water model experiments show that the hole number, hole shape, and the gas pressure can affect the residence time of the CH₄ bubble, with the optimized parameters being 25, circular, and 0.55 MPa, respectively. The numerical simulations further reveal that the prolonged duration time at optimized cross-sectional structure of the nozzle is due to the decrease in bubble sizes. The results can hopefully provide new insights for practical designing toward the high-efficiency utilization of naturals gas for copper plants.