Failure Analysis and Corrective Actions for Propane Gas Feed Pipes in Copper Anode Furnaces

Boliden Harjavalta uses propane as reductant in copper anode furnace. Propane is fed via specific gas feeding pipes to furnace. In the summer of 2022, the wear of propane gas feed pipes in the Boliden Harjavalta copper anode furnace increased significantly, with a peak of 84 replacements in July, compared to the usual 5–20. This paper presents a summary of failure analysis, actions taken, and current situation. Analysis revealed that chloride-induced corrosion and poor welding quality in gas feed pipe were primary causes of pipe failures. Installation practices also may have contributed to the issue, exposing structural steel to molten copper. To address this, operating instructions were reviewed, and trials with different materials were conducted. Eventually, thicker single-material pipes were used, reducing the need for replacements to 3–9 per month by early 2024.