What Refractory Brick for Aluminium Melting Furnaces? How to Choose High Alumina Brick

Lining selection for aluminium and aluminium-alloy melting furnaces is very different from the steel industry. Aluminium melt has low viscosity and strong penetration, so the brick porosity and erosion resistance matter a lot; melting temperatures are mostly 700-900°C, but local spots (door, charging port) face higher temperatures and mechanical impact. Wrong brick means short lining life, frequent hot repairs, or even melt leakage that contaminates the aluminium. This article explains the selection logic for high alumina brick in aluminium melting furnaces.

Requirements of Each Furnace Zone

### Melt Pool and Lower Walls

The inner wall directly contacts the melt. Attack appears as penetration and chemical erosion - the higher the porosity, the deeper the penetration, causing spalling and contamination. Use dense high alumina brick with low apparent porosity (Al₂O₃ ≥ 65%).

### Upper Walls and Roof

These zones do not contact the melt directly but suffer thermal shock and flue erosion. Al₂O₃ 55-65% high alumina brick is suitable here.

### Door, Charging Port and Skimming Port

Repeated thermal shock and mechanical impact make these the weakest spots. Use high-strength high alumina brick or prefabricated parts locally, and reserve room for hot repair.

High Alumina Brick vs Fireclay Brick vs Mullite Brick

The problem with fireclay brick in the melt pool is its relatively high porosity and low Al₂O₃: aluminium melt penetrates easily and lining life is clearly shorter. High alumina brick is the most balanced choice - that is why it dominates aluminium processing.

Five Key Indicators

1. Al₂O₃ content - LZ-55/65/75 grades; use LZ-65 or above where contacting melt
2. Apparent porosity - the lower the better for melt contact (≤23%, premium ≤20%)
3. Bulk density - denser means better penetration resistance (LZ-65 usually ≥2.5 g/cm³)
4. Refractoriness under load - generally ≥1420-1450°C, higher for load-bearing spots
5. Dimensional accuracy - tight joints prevent melt leakage; shaped zones need custom moulds

How to Judge Custom + Prefab Capability

1. Custom shaped brick capability - wedge, arch and special shapes by drawing, and mould lead time
2. Prefabricated parts production - door frames, launders etc.
3. Lining scheme support - brick type selection and joint control
4. Complete physical/chemical testing - Al₂O₃, porosity, bulk density, RUL data per batch

Henan Songrui New Refractory Materials Co., Ltd. (Grade-A taxpayer, provincial specialized and sophisticated SME) supplies LZ-55/LZ-65/LZ-75 high alumina brick series with custom shaped brick moulding and prefabricated parts. For high alumina brick and custom brick inquiries contact Manager Zheng: 17513376789.