Batching Specifications of Silica Brick

The batching of silica brick will directly affect its physical and chemical properties and the rate of final products. When determining the batches of silica brick, its technology requirements, applications, size and shape should be taken into consideration. 

Since the silica brick has crystal transformation when fired, when batching, it is necessary to consider the closest packing of particles and the heating, molding and firing characteristics of the raw materials. If the silica material is of rapid transformation, it should not be used alone because it has loose structure after fired and is difficult to make bricks without cracks. The advantage of silica material with slow transformation is that its transformation is relatively dispersed at different temperatures rather than concentrated in a certain temperature range, which makes the expansion during firing relatively stable and reduces the possibility of cracking. 

 

During the production, the particles are usually of natural size after crushed. The critical size is 2-8 mm. The addition amount of the powder depends on the molding method. For ordinary machine pressed bricks, it is 10-20%. For hand molded bricks, it is as high as 30-40%. 

 

To improve the plasticity and associativity of the mud and promote the transformation of the quartz crystals, an appropriate amount of binding agents and mineralizing agents are added. The common binding agent added is pulp waste and the common mineralizing agent is ferric oxide powder (mill scale, open hearth slag, etc.) and lime. The lime is usually added in the form of lime milk and acts as a binding agent at room temperature. The selection of the binding agents and mineralizing agents are determined according to the chemical composition and the actual situation of each plant. 

 

In order to reduce the volume expansion when fired and the residual expansion when used, a certain amount of waste bricks should be added into the batch materials. But too many waste bricks will affect the physical and chemical properties of the final products. Therefore, the predetermined amount is 10-20%. When producing bricks with big unit weight, complex shape and low specific gravity, the amount can be increased to 30-40%.