Refractory Brick Production: Raw Material Processing

During the production process of refractory bricks, although different refractory products are made with different raw materials and the production conditions are different, the production processes and processing methods are almost the same. The basic process includes crushing, fine grinding, screening, ingredients, kneading, shaping, drying and firing. 

The processing of raw materials includes crushing and screening. 

 

 

The refractory clinkers or raw materials always have different shapes and sizes. Their sizes can be powders or 350mm blocks. Experiments and theory calculations show that mud with single-size particles cannot be packed tightly and only mud composed of large, medium and small particles can get dense green bodies. So, bulk refractories must be crushed to meet the size requirements for preparing mud.

 

Raw materials are crushed mechanically or by other methods. Bulk materials are processed into granular and powdered materials. The process includes coarse crushing, middle crushing and fine grinding. 

 

(1) Coarse crushing

 

The size of the materials is crushed from 350 mm to 50-70mm. Different jaw crushers are used. It crushes materials by the periodically reciprocating motion of movable jaws to the fixed jaw plate. 

 

(2) Middle crushing

 

The size of materials is crushed from 50-70mm to 5-20mm. Machines used include cone crusher, double roll crusher, impact crusher and hammer crusher. 

 

(3) Fine grinding

 

The size of materials is ground from 5-30mm to 0.088 mm or 0.044 mm, or even 0.002 mm. The machines used include tube mill, Raymond mill, vibrating mill, jet mill and mixing mill. 

 

The main factors for crushing include the strength, hardness, ductility, and moisture of the materials and the crushing equipment. During the actual production, crushing materials from 350 mm to 3-0.088mm requires continuous crushing operations. According to the structure and properties of the crushing equipment, corresponding equipment is combined to conduct continuous crushing operations. 

 

During the crushing process, a certain amount of metallic iron impurities are inevitably brought into the materials. These metallic iron impurities have bad effect on the high temperature properties and appearance of the products, so they must be removed. They can be removed by physical and chemical iron removing methods. The physical method is to remove iron with a strong magnetic separator. The chemical method is pickling. It is mainly used in the high-purity white fused alumina and other raw materials to ensure the purity of the materials.  

 

 

After crushing, large, middle and small particles are mixed. To meet the size requirements on particles, materials should be screened. During the process, the fine material that passes through the sieve is called sieve passage, while the coarse material that remains on the sieve is called sieve residue. 

 

The size of sieve passage is up the size of the sieve mesh and its tilt angle, the moving speed of powder materials on the sieve surface, the thickness of the mesh, the moisture of the powder materials and the shapes of particles. The size of sieve passage can be adjusted by changing the tilt angle or the moving speed of powder materials on the sieve surface.

 

Currently, the screening equipment used in the production of refractory materials includes vibrating screen and fixed inclined screen. The screening efficiency of the former is up to 90%, while the latter is usually around 70%.