LZ-75 High alumina brick

Product Overview

Our LZ-75 High Alumina Bricks are premium-quality, high-performance shaped refractory products specifically engineered for the most demanding glass furnace applications. The “LZ-75” designation follows the Chinese National Standard classification, where “LZ” stands for “high alumina brick” , and “75” indicates a nominal alumina (Al₂O₃) content of ≥75% .

According to Chinese classification standards, high alumina bricks with Al₂O₃ content exceeding 75% are classified as Class I high alumina bricks—the highest grade in the standard high alumina brick family . LZ-75 bricks represent the premium tier of conventional high alumina refractories, offering exceptional refractory properties for critical glass furnace zones requiring maximum performance.

Manufactured from selected high-quality bauxite with enhanced purity control, LZ-75 bricks undergo a rigorous production process including batching, mixing, high-pressure forming, and sintering at controlled temperatures of 1500-1600°C in tunnel kilns—significantly higher than lower grade bricks . This elevated firing temperature ensures complete phase transformation, resulting in a dense microstructure featuring corundum and mullite as the predominant mineral phases with minimal glass phase.

With 75% Al₂O₃ content, LZ-75 bricks deliver superior refractory performance compared to LZ-55 and LZ-65 grades, making them ideal for glass furnace zones subjected to the most severe thermal and chemical conditions .

Key Features & Benefits for Glass Industry

• Exceptional Refractoriness for Extreme Glass Furnace Conditions: LZ-75 bricks offer outstanding heat resistance with a refractoriness of ≥1790°C, making them suitable for the most demanding high-temperature environments of glass melting furnaces, including areas with flame impingement and localized overheating .

• Superior Load-Bearing Capacity at Elevated Temperatures: With a refractoriness under load (0.2MPa) of ≥1520°C, these bricks maintain excellent structural integrity under both thermal and mechanical stress in critical glass furnace superstructure applications .

• Outstanding Resistance to Glass Batch Attack: As a chemically neutral refractory with high alumina content, LZ-75 provides superior resistance to corrosion by both acidic and alkaline components present in glass batch materials and furnace atmospheres .

• High Mechanical Strength for Extended Durability: Cold crushing strength of ≥50-70 MPa ensures exceptional durability during transport, installation, and throughout the demanding service life in glass furnace applications .

• Excellent Volume Stability at High Temperatures: Controlled permanent linear change (+0.1 to -0.4% at 1500°C×2h) ensures exceptional dimensional stability during the furnace campaign, maintaining tight joints and structural integrity throughout the service life .

• Enhanced Thermal Shock Resistance: LZ-75 bricks offer improved resistance to thermal cycling compared to lower alumina grades, making them suitable for glass furnace zones subject to temperature fluctuations .

• High Bulk Density: With bulk density of 2.5-2.65 g/cm³, LZ-75 bricks provide excellent mechanical strength and low permeability, contributing to extended service life .

Applications in Glass Industry

LZ-75 high alumina bricks are specifically engineered for the most critical zones of glass melting furnaces where maximum performance is required:

Primary Glass Furnace Applications:

• Glass Furnace Superstructures: Upper walls, breast walls, and regenerator crowns in the hottest zones where temperatures exceed 1550°C and alkaline vapor exposure is most severe .

• Burner Blocks: Areas subject to direct flame impingement and extreme thermal stress, requiring materials with maximum refractoriness and thermal shock resistance .

• Port Arches and Port Necks: Flame port structures directing combustion gases into the melting chamber, requiring excellent thermal shock resistance and mechanical strength .

• Regenerator Chambers: Top checker bricks and chamber linings in the hottest zones of regenerator systems, where thermal cycling and chemical attack are most aggressive .

• Glass Furnace Bottoms: Working lining in high-wear zones of the melting tank bottom.

• Doghouse Areas: Batch inlet regions subject to severe thermal shock and mechanical abrasion from raw materials .

Secondary Glass Industry Applications:

• Specialty Glass Furnaces: For borosilicate, aluminosilicate, and other specialty glass compositions where maximum refractory performance is essential.

• Glass Tank Forehearths: Channels and distributor blocks in high-temperature distribution systems.

• Glass Melting Electrode Blocks: Areas surrounding electric boosting electrodes where localized superheating occurs.

Other Industrial Applications (Reference):

LZ-75 high alumina bricks are also widely used in:

• Steel Industry: Electric arc furnace roofs, ladle linings, blast furnace linings, hot blast stoves, and reheating furnaces

• Cement Industry: Rotary kiln transition zones and cooler linings

• Ceramic Industry: Tunnel kiln linings and kiln furniture for high-temperature firing

• Non-Ferrous Metals: Smelting and refining furnaces for copper, aluminum, and other metals

• Chemical Industry: High-temperature reactors and reformers

Why Choose Our LZ-75 High Alumina Bricks for Glass Furnaces?

Our LZ-75 high alumina bricks are manufactured specifically with demanding glass industry requirements in mind:

Manufacturing Excellence:

• Raw materials undergo rigorous grading, sorting, and magnetic separation to remove impurities that could affect glass quality .

• High-pressure forming ensures uniform density and accurate dimensions for tight joint construction .

• Controlled high-temperature firing at 1500-1600°C in tunnel kilns ensures complete phase transformation and consistent quality .

• 100% dimensional inspection before packaging ensures proper fit during installation .

Glass Industry Quality Assurance:

• Chemical composition verified by XRF analysis to ensure Al₂O₃ ≥75% and Fe₂O₃ within specification.

• Physical properties tested per ASTM/GB standards to ensure reliable performance.

• Low iron content minimizes risk of glass defects from refractory contamination.

• Thermal shock resistance and creep testing available upon request for specific glass furnace applications.

Technical Support:

• Thermal calculation and material selection support based on furnace operating conditions.

• Professional lining design team for customized solutions.

• On-site installation guidance and supervision available.

• Special application consultation for critical glass furnace zones.

With extensive experience in refractory manufacturing for the glass industry and ISO 9001 certification, our technical team provides comprehensive support, from material selection and furnace design consultation to installation guidance .

For Inquiries:

Contact our glass industry specialists for application engineering support, custom sizing, or to discuss which high alumina brick grade is optimal for your specific glass furnace design and operating conditions. We provide detailed technical data sheets, shop drawings, and certification documents with every order.