1. Select High-Quality Refractory Materials (Most Critical)

• Use high-alumina (85–99% Al₂O₃) precast shapes or premium castables with non-wetting additives.
• Best materials: Fused silica, silicon carbide (SiC)-bonded, or high-purity alumina with boron nitride (BN) coating.
• Covered (enclosed) launders last 30–50% longer than open ones because they reduce oxidation and thermal shock.
• Avoid cheap fireclay or low-grade castables — they wet easily and erode quickly.

2. Strict Preheating Procedure

• Never introduce molten aluminum into a cold launder.
• Slowly preheat the entire system to 600–700°C for at least 2–4 hours.
• Keep temperature difference across the launder below 100°C to prevent thermal shock cracking.
• Use uniform heating (gas or electric).

3. Optimize Metal Flow and Level

• Maintain flow velocity at 0.3–0.6 m/s (preferably below 0.5 m/s) to minimize erosion.
• Keep metal depth at 60–80% of launder height.
• Avoid frequent start/stop cycles — continuous steady flow is ideal.

4. Regular Cleaning and Maintenance

• Clean residual aluminum and dross after every shift using non-metallic tools only.
• Inspect regularly for wear, cracks, or metal penetration.
• Repair local damage immediately with matching refractory patch.
• For covered launders, replace sealing gaskets when they become hard or damaged.
• Periodically bake out the launder (400–500°C) during planned shutdowns.

5. Keep the Melt Clean

• High oxide and inclusion levels accelerate refractory attack.
• Use proper degassing + ceramic foam filtration (CFF) before metal enters the launder.
• Cleaner melt = longer launder life.

6. Temperature Control

• Operate ideally at 700–750°C. Avoid long periods above 760°C.
• Minimize empty (dry) running of the launder.
• Use insulated or heated covers to reduce temperature drop and thermal cycling.

7. Smart Design Features

• Use modular/sectional design so high-wear areas (inlets, elbows, outlets) can be replaced independently.
• Install proper multi-layer insulation (calcium silicate + working lining).
• Consider electrically or gas-heated launders for longer transfer distances.

Typical Service Life Comparison

Summary The three keys to long launder life are: Right material + Correct preheating & operation + Consistent maintenance.

Follow these practices and most aluminum plants can easily double or triple their launder service life while reducing production costs.