Glass defects that may be caused by refractory bricks for glass kilns

Glass defects caused by refractory bricks may be of the following three types:

1. Stones

When larger particles of refractory bricks for glass kilns fall into the glass melt and cannot be completely dissolved by the melt, "stones" will appear in the glass. Particles with higher specific gravity will settle to the bottom of the pool. Insoluble substances such as ZrO2 can also be dispersed into very small particles without causing harm.

The alkali in the glass will react with refractory bricks containing alumina to form feldspar substances. Due to the difference in thermal expansion, thin flakes fall off. After falling off, new flakes are generated to cause harm. Those unsintered particles in the ramming material may also enter the glass and form stones

2. Bubbles

Organic impurities attached to the surface of refractory bricks will be burned to produce bubbles. Some inorganic building materials also tend to produce bubbles in the initial stage.

In addition, the air discharged from the holes of refractory bricks can also cause bubbles. Carbon-containing impurities are always the source of bubbles.

Metallic iron itself does not tend to produce bubbles, but the carbon contained in it does. Substances with redox potential will also produce bubbles due to changes in oxidation conditions in the melt. Zircon bricks also tend to produce bubbles in the early stage of use. However, after the action of the alkali in the glass, the quality is improved and bubbles no longer occur.

3. Indirect defects

The alkali in the glass and the material containing Al2O3 are combined to form a stone-like substance. In a certain temperature range, this substance cannot be completely dissolved and leaves "stones". Alumina may dissolve or semi-dissolve, leaving ZrO2 as "stones". The corrosive components of the glass may dissolve SiO2 in zircon products and leave ZrO2 stones. If the particles are large enough, stones will appear in the glass. The above particles will also be produced on the eroded checker bricks. When the combustion air passes through the checker brick masonry, it may blow them (parts of the checker bricks, the damaged refractory brick parts or their components) into the melt and cause the formation of "stones". Refractory bricks falling from the upper structure or the top of the kiln may also form stones.