Application of Silica Brick in the Crown of Glass Furnaces

Application of Silica Brick in the Crown of Glass Furnaces

Silica bricks are one of the most commonly used refractory materials. Due to its low cost, high creep resistance and low contamination to glass, it is widely used for the roof of glass kilns. Silica bricks are an alkaline refractory material with good corrosion resistance to acid slag.

It is mainly made of natural silica sand whose SiO2 content should be above 96%. The higher the SiO2 content in silica sand, the higher the temperature resistance of silica bricks. Its crystal structure consists of scaly quartz, square quartz and a small amount of residual quartz as well as the glass phase.

Silica Brick for Coke Oven

The refractoriness of silica brick is not very high, about 1600-1730℃, but it has a high charge melting temperature, about 1620-1670℃, which is similar to its refractoriness and the melting temperature of squamous quartz. It is durable and does not deform at high temperature.

At 1450℃, the overall expansion is 1.5-2.2%, which makes the joints dovetail, thus the silica brick has good air tightness and strong structure.

Silicon bricks have good thermal shock resistance above 650℃, so they are mainly used in continuous operation furnaces. However, below 650℃, the thermal shock resistance is poor, and the temperature should be raised slowly during the baking process.

Silica bricks have good corrosion resistance to glass liquor. In terms of cost, strength and potential defects, it is the preferred refractory material for the roof structure of glass melting furnaces.

Since silica bricks are sensitive to alkali corrosion, their service life is considerably shortened in oxyfuel furnaces where the furnace roof suffers from severe alkali vapor corrosion. Electrofused AZS blocks and electrofused alumina blocks are used as a replacement for silica bricks in oxyfuel furnaces. However, they are large and heavy, which increases the cost and load of the crown. Therefore, in order to meet the requirements of oxyfuel furnaces and to reduce costs, high-quality silica bricks with better corrosion resistance were developed.