The sintering method is to pre-sinter some raw materials into clinker, crush and screen them, then mix them with raw materials in a certain proportion, and then go through shaping, drying and firing. The purpose of pre-burning the raw materials is to burn out the moisture, organic impurities, and gases caused by the decomposition of sulfates, so as to reduce the firing shrinkage of the products and ensure the accuracy of the outer dimensions of the products. The raw materials also need to be screened after crushing and grinding, because the blanks are graded from powders of different particle sizes to ensure the tightest packing and obtain a dense body.
In order to homogenize the components and particles of various raw materials and clinkers, they must be mixed and binders must be added to enhance the bonding strength of the blanks. For example, binder clay is added to aluminum silicate blanks, sulfite pulp waste liquid is added to magnesia blanks, lime milk is added to siliceous blanks, etc. Depending on the moisture content of the blank, semi-dry molding (containing approximately 5% moisture), plastic molding (containing approximately 15% moisture) and slip molding (containing approximately 40% moisture) can be used. It is then dried and fired.
The melting and casting method involves mixing the raw materials and fine grinding, melting them at high temperatures, casting them directly, and then cooling, crystallizing, and annealing them into finished products. Such as fused cast mullite bricks, corundum bricks and fused magnesia bricks, etc. Their green bodies are dense, have high mechanical strength, high-temperature structural strength, and good slag resistance, and their scope of use is constantly expanding.
The melt blowing method is a method in which the ingredients are melted and then blown with high-pressure air or superheated steam to disperse them into fibers or hollow balls. The products are mainly used as lightweight refractory and heat-insulating materials. In addition, it can also be made into powdery or granular amorphous refractory materials, which are cemented with binders such as tar, asphalt, cement, phosphate, sulfate or chloride salts for temporary use, and can be used directly without forming and sintering.
