There are two kinds of brick-making methods for magnesia-carbon bricks: fired oil-impregnated magnesia-carbon bricks and unburned magnesia-carbon bricks. The former brick-making process is more complicated and is rarely used. Here, only the characteristics of the brick-making process of unburned magnesia-carbon bricks are briefly described.
Preparation of mud. The choice of particle critical size is important during breeding. Refinement of aggregate particles can reduce open porosity and enhance antioxidant capacity. However, the small aggregate particles will increase the closed pores and reduce the bulk density. In addition, fine-grained MgO aggregates are easy to react with graphite, and it is generally considered that the particle size of 1 mm is suitable. Under the condition of high pressure molding equipment, the particles of magnesia tend to be micronized. The pressure of molding equipment in my country is low. In order to increase the density of refractory bricks, many manufacturers use particle diameters of more than 5mm.
The quality and quantity of graphite added to the ingredients are critical. Generally speaking, increasing the graphite content in the refractory brick will improve the slag resistance and thermal shock stability of the refractory brick, but the strength and oxidation resistance will decrease. If the network skeleton cannot be formed in the refractory brick, the advantages of carbon cannot be effectively exerted. Therefore, the carbon content is more suitable in the range of 10-20%.