Molten aluminum launders (molten aluminum transfer troughs) deliver liquid aluminum from melting furnaces to casting, degassing and filtration units. Their refractory linings are critical to prevent metal contamination, resist thermal shock and block molten aluminum penetration. Choosing the right refractory directly impacts launder service life, casting quality and operational cost in aluminum foundries and smelters.
Fused silica is the most widely adopted refractory for aluminum launder hot faces. It features ultra-low thermal expansion, excellent thermal shock resistance and non-wetting performance against molten aluminum. Precast fused silica launder segments and fused silica castables withstand repeated heating and cooling cycles without cracking. They reduce dross adhesion and keep aluminum purity stable, making them ideal for primary aluminum and high-grade alloy casting lines.
High-alumina castables and mullite precast blocks are common alternatives. With high hot strength and good corrosion resistance, they are suited to heavy-duty launder sections with fast molten aluminum flow. Mullite refractories show low reactivity with liquid aluminum, making them suitable for medium-temperature transfer channels. Low-cement high-alumina castables are easy to cast and repair on-site, and are popular for custom launder shapes and maintenance projects.
Aluminum silicate refractories work as both lining and insulation layers. Ceramic fiber launder components are lightweight with outstanding heat retention, minimizing temperature drop during long-distance aluminum transfer. They help avoid cold shut defects yet have lower mechanical erosion resistance, so they are more often used for low-flow secondary transfer lines or as backup insulation behind the working lining.
Calcium silicate boards and lightweight refractories back up the main working lining to cut heat loss. Boron nitride (BN) or dedicated anti-aluminum wetting coatings are applied on refractory surfaces. These coatings further stop molten aluminum sticking and simplify daily cleaning.
When selecting launder refractory, evaluate aluminum alloy grade, flow velocity, operating temperature and thermal cycling frequency. High-purity aluminum casting usually calls for fused silica. Heavy-wear zones favor high-alumina mullite materials. Insulation-focused projects can combine ceramic fiber with dense working linings.
Poor refractory selection causes cracking, aluminum infiltration and dross buildup, triggering frequent downtime. Matching refractory properties to your aluminum transfer process extends lining lifespan and stabilizes metal quality.
