Why Does the Quality of Fused Mullite Bricks Have an Effect on Glass Stones?

In glass melting furnaces, zirconium-containing refractories include fused mullite bricks (commonly known as black iron bricks) and fused zirconium corundum bricks (commonly known as white iron bricks). These two types of bricks are key factors in the production of zirconium refractory stones from glass.

 

The electric fused mullite is an important refractory material for the masonry glass wall and the liquid-flowing hole. The working surface that contacts the molten glass is light red, and the interior of the brick is still black-gray. The brick is eroded and appears on the surface of the board. Most of the stones are yellowish white and white enamel, and the particles are small, resulting in high density and hardness. The composition of the fused mullite brick ore: mullite, oblique zircon, glass phase, mullite in the structure is plate-like, columnar; oblique zircon is granular, chain-like and mullite intertwined together, electricity The alteration of the molten mullite brick is mainly due to the presence of some glass phases in the brick. In the process of erosion, the glass component absorbs the alkaline component and reacts with mullite to form corundum, β-corundum and nepheline. The refractory oblique zircon is melted into the glass liquid, and if there is sufficient time to react, the secondary crystal skeleton-like, pine-like oblique zircon can be precipitated.

Why does the quality of fused mullite bricks have an effect on glass stones?

Mullite is the result of erosion treatment of alkali-containing glass on silica-alumina refractories. It is needle-like and column-shaped under the microscope. The protrusions are high, the birefringence is medium, and there is chromaticity of light red to light green. Long needle-like, often associated with nepheline. Nepheline is a product of the diffusion of alkaline components in glass and refractory materials. It appears in the late stage of erosion and is hexagonal, stepped, sometimes feathery, short columnar, columnar, optical and Quartz is similar, the interference color is low, and there is a polycrystalline twin. Nepheline is often associated with corundum. The oblique zircon is the main crystalline phase of the zirconium corundum brick. The oblique zircon crystal formed by the reaction between the brick body and the alkaline component in the glass is a secondary crystal, which is a fine granular shape or a skeleton shape in which the stem and the branch are at an angle of 90°. The distinction between the various forms of oblique zircon and the skeleton-shaped cristobalite is that the oblique zircon has a high protrusion and a high birefringence, often co-existing with nepheline. Figure 1 shows the formation of a portion of zirconium refractory stones.

 

To prevent zirconium refractory stones, high-quality refractory materials must be used; reduce the flying of fine powders during feeding; strengthen the protection of the pool wall to avoid contact with the pool walls; strictly control the quality of raw materials, eliminate the introduction of zirconium stones; strengthen the melting Operation to reduce large fluctuations in the liquid level of the glass.

 

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