An aluminum recycling facility was grappling with a persistent and costly operational challenge in its holding furnaces. The furnace walls were experiencing severe dross adhesion and the growth of hard, corundum-based buildups. This not only made cleaning the furnace difficult and labor-intensive but also led to two significant problems: silicon contamination of the aluminum melt, and frequent downtime for mechanical cleaning, which was damaging the refractory lining and shortening its lifespan.

The plant’s output was suffering due to reduced furnace availability and product quality issues. They turned to the material experts at Pennekamp Middle East for a lasting solution.

Diagnosing the Problem: A Fundamental Chemical Mismatch

A thorough analysis of the plant’s operations revealed the root of the problem. The furnace was lined with a standard silica-containing refractory, a common choice for general-purpose applications but highly unsuitable for direct contact with molten aluminum.

The issue is a fundamental chemical reaction. Molten aluminum is highly reactive and acts as a powerful reducing agent. It was attacking the silica (SiO₂) in the refractory lining, “stealing” the oxygen atoms to form aluminum oxide (Al₂O₃), or corundum, and leaving behind free silicon, which was then dissolving into the aluminum melt. This reaction was simultaneously creating the hard buildups on the wall and contaminating the product.

The Solution: An Engineered, Non-Wetting Refractory Lining

The Pennekamp team recommended a complete change in material science. The solution was to reline the furnace’s metal contact zone with a specialized, low-silica, high-alumina castable refractory that incorporated advanced non-wetting agents.

• How it Works: These special additives work at the microscopic level to alter the surface energy of the refractory. They create a repulsive force at the interface between the lining and the molten aluminum, preventing the metal from “wetting” or sticking to the surface. This effect is similar to how water beads on a waxed car.
• The Benefits: By preventing the molten aluminum from adhering to the walls, this non-wetting technology dramatically reduces the formation of dross and corundum buildup.

The Results: Improved Quality, Increased Output

After the installation of the new non-wetting refractory lining, the plant experienced a dramatic operational turnaround:

• Higher Product Purity: Silicon pickup from the lining was virtually eliminated, allowing the plant to produce a higher quality, higher value final product.
• Easier and Faster Cleaning: The minimal dross that did form did not adhere strongly to the walls and could be removed easily without aggressive mechanical force.
• Extended Lining Life: Because the destructive cleaning cycles were no longer necessary, the campaign life of the furnace lining was significantly extended.
• Increased Furnace Availability: The reduction in downtime for cleaning and repairs meant the furnace was online and producing metal for more hours each month, leading to a direct increase in plant output.

This case clearly demonstrates that for non-ferrous metal production, choosing a refractory with the correct, specialized chemistry is not just a maintenance decision—it is a critical factor for productivity and profitability.

Solve Your Non-Ferrous Refractory Challenges

If your aluminum, copper, or zinc operation is facing challenges with metal contamination, dross buildup, or short refractory life, Pennekamp Middle East has the solution. We specialize in providing engineered refractories for non-ferrous applications.

Contact us today for a consultation with our material experts and let us help you find the right solution to improve your plant’s performance.