The Process and Characteristics of Producing Semi-silica Bricks

The process of producing semi-silica bricks by Xinhongji Refractory can be divided into two types: fired and unfired. Unfired bricks are mainly made of sodium silicate as a binder. The production processes of fired bricks and clay products are roughly the same, but they also have their characteristics, mainly reflected in the following points.

1. Whether to add clinker is determined based on the raw materials’ characteristics and the product’s usage requirements. Siliceous clay has a small sintering shrinkage and no clinker is used. To improve the thermal shock resistance of semi-silica bricks, 10 to 20% clinker should be added.

2. If there are few fusible materials in the raw material and the quartz particles are coarse, the semi-silica brick will have low density and poor strength, but it will have good thermal shock performance and high load softening temperature; otherwise, the product will have poor fire resistance and thermal shock resistance. Therefore, the addition of quartz sand or siliceous clinker should be determined according to the use conditions of the product. Determine whether to add granular material or fine particle material.

3. When the temperature is lower than 1250°C, the volume shrinkage of semi-silica bricks is not obvious, and as the high-temperature liquid phase content increases, the volume shrinkage is larger. Therefore, within the sintering temperature range of clay bricks, the density of silica bricks should generally be higher than 1410 degrees of clay bricks.

4. When using wax stone as the raw material for semi-silica bricks, the process should be determined based on the chemical composition of the raw material. After pyrophyllite is dehydrated, its main components still maintain a small amount of lattice structure. Therefore, the raw materials can be directly used to make bricks, making full use of mineral resources and reducing production costs. To prevent sintering expansion and strength reduction, wax stone raw materials can be calcined into mature raw materials, and a small amount can be added during batching. It should also be noted that wax stone has poor water absorption and the water content of the slurry should be strictly controlled, otherwise, cracks will appear during the molding process.

Semi-silica bricks have good acid slag resistance, high-temperature structural strength, and volume stability. They are mainly used in coke ovens, acid cupolas, metallurgical furnace flues, and ladle linings.