Key Properties and Parameters of Vermiculite Boards:
High-Temperature Resistance: Melting point approx. 1370–1400°C, maximum operating temperature approx. 1200°C, suitable for electrolytic cell operating conditions of 950–970°C.
Thermal Insulation: Thermal conductivity approximately 0.04–0.13 W/(m·K), typically around 0.04–0.06 W/(m·K).
Corrosion Resistance / Permeation Barrier: Inhibits permeation of cryolite-alumina molten salts and fluoride compounds.
Mechanical & Safety: Compressive strength: 0.3–10 MPa; Density: 500–1200 kg/m³; Non-combustible (Class A), non-toxic.
Performance of Vermiculite Boards in Electrolytic Aluminum Cell Projects (Excerpts):
A 500 kA series cell with an 80 mm vermiculite insulation layer achieved a cell voltage drop reduction of approximately 30 mV and a decrease in DC power consumption per ton of aluminum by about 100 kWh.
Vermiculite anti-seepage bricks installed beneath cathode carbon blocks in a 500 kA cell significantly reduced furnace bottom pressure drop and extended service life.
Key Selection and Installation Guidelines for Vermiculite Boards:
Thickness and Density: Typically 50–100 mm for cell bottoms/side walls; prioritize densities of 600–1000 kg/m³ for balanced thermal insulation and strength.
Composite Structure: Inner refractory bricks/castables resist erosion, intermediate vermiculite panels provide insulation, outer layer sealed or steel-plated.
Installation and Sealing:
Offset joints with high-temperature sealant/mortar filling; reinforce edges, corners, and openings to prevent thermal bridges.
Hot-State Anchoring:
Use high-temperature anchors in zones ≥600°C to prevent displacement or detachment.
Quality Control:
Spot-check density, compressive strength, thermal conductivity, and flexural strength; verify flatness and joint integrity during installation.
