X‐ray Computed Tomography Characterization of Slag Crust and the Effect of Bubbles and Metallic Iron in Slag on Heat Transfer to Copper Stave

Abstract

Understanding the heat transfer properties of the slag crust is critical to the safe operation of copper staves. The distribution of metallic iron and bubbles in the slag crust is detected by X‐ray computed tomography. The thermal conductivity of the slag crust is modified based on an effective thermal conductivity model and laser thermal conductivity measurements to predict the effect of metallic iron and bubbles on the heat transfer in the slag crust. The results show that the average volume fractions of metallic iron and air bubbles in the slag crust are 3% and 4.5%, respectively. The measured value is consistent with the trend of the effective thermal conductivity calculation model, and the calculation result of the Maxwell–Eucken effective thermal conductivity model is very accurate. Variations in the volume fraction of metallic iron in the slag crust have a greater effect on the thickness of the slag crust, while variations in the volume fraction of bubbles have a smaller effect on the thickness of the slag crust. It is recommended to keep it between 10 and 30 mm in blast furnace production to help improve the operational life of the copper stave.

Damage Mechanism of Copper Cooling Plate on Large Blast Furnace

“…When the blast furnace is in operation, metallurgical slag with a thickness of 30-50 mm condenses on the hot surface of the cooling stave to protect it from damage. [6][7][8][9] In China, the copper cooling stave of blast furnaces larger than 4000 m 3 frequently fails after 7-10 years of service. Only a few 2500 m 3 furnace copper cooling staves can last about 15 years.…”