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.
Magnesia-carbon bricks are made of high melting point alkaline oxide magnesia (melting point 2800°C) and high melting point carbon materials that are difficult to be infiltrated by slag as raw materials, and various non-oxide additives are added. A non-charcoal composite refractory material combined with a carbon binder. Magnesia-carbon bricks are mainly used in converters and AC electric arc furnaces.
As a composite refractory material, magnesia-carbon brick effectively utilizes the strong slag erosion resistance of magnesia and the high thermal conductivity and low expansion of carbon, which compensates for the poor spalling resistance of magnesia.
Its main features are:
1. Has good high temperature resistance
2. Strong slag resistance
3. Good thermal shock resistance
4. Low creep at high temperature
Raw materials have a great influence on the performance of magnesia-carbon bricks, and the quality of magnesia has an extremely important influence on the performance of magnesia-carbon bricks. How to reasonably select magnesia is the key to producing magnesia-carbon bricks. Magnesia includes fused magnesia and sintered magnesia.
they have different characteristics
1. Fused magnesia: large grains, few impurities, few silicate phases, high direct bonding degree of grains, and few grain boundaries.
2. Sintered magnesia: the grains are small, the impurities and the silicate phase are relatively large, and the degree of direct bonding is poor.
The slag splash layer has good corrosion resistance and can reduce the mechanical scouring of the furnace lining during the steelmaking process, thereby protecting the furnace lining bricks, slowing down their damage, and improving the life of the furnace lining.