This article is following the last article talks about the second and third choices of Magnesia carbon brick raw materials.
2. Types of magnesium sand
There are three main types of magnesium in production: magnesium, sintering magnesium, and electric melting magnesium.
Sea Water Magnesium: The production of seawater magnesium sand began in 1855. The advantages of seawater magnesium are high purity, MGO content is above 95%, chemical composition is easy to adjust, and particle volume density is as high as 3.30 ~ 3.49g/cm3.
Magnote of sintering magnesium: Advanced sintering magnesium sand is a product composed of magnesium, white cloud stone sand, chromium powder and square magnesium stones. The characteristics of advanced materials are: MGO content between 96 and 99%and the volume density is above 3.40g/cm3. The magnesium carbon bricks used in the steel mill are mainly used as asphalt or resin -binding magnesium carbon bricks for the high corruption site of oxygen -blowing furnace and electric furnace.
Electric magnesium: The so -called electric melting refers to the melting of high -temperature arcs in the arc furnace. Its raw materials can be a special -grade natural diamond magnesium ore or a high -purity light magnesium oxide. Electric melting magnesium sand has the advantage that other magnesium sand cannot be compared, high -temperature resistance, large volume density, extremely low air perforated, dense structure, high chemical stability, high strength, certain insulation, abrasion resistance resistance, wear resistance resistance Flush, resistance to slag corrosion. It has been widely used in high -temperature firing, induction furnaces, arc furnaces, high -temperature easily damaged sites and cement rotary kiln transition bands, furnaces, and furnaces of high -temperature tunnel kiln.
The high -grade electric magnesium sand grain grains are basically greater than 80 μm, and the grains are directly combined, so there are few siliconate and less crystal world; and the grains of sintering magnesium are basically under 60 μm — below the grain, and the spar between grains is directly combined with the combination of grains. The degree is poor, and the grains are filled by the low -melting point silicate, so the corrosion resistance is poor. Therefore, most of the production manufacturers of magnesium carbon bricks are now using electricity magnesium and without sintering magnesium. This is the reason.
3. Types of the binding agent
The substances that can be used as a combination of magnesium carbon bricks are summarized as follows: coal -based tar, asphalt, and petroleum asphalt. Traditional asphalt combined with magnesium carbon bricks is cheap, with reliable use, high carbon rate, oil asphalt has strong affinity for magnesium oxide, but due to the elasticity of graphite after molding The body was not dense, and later began to use thermosette phenolic resin to obtain a good body strength, and the antioxidant performance and thermal shock performance were improved. During the heat treatment process, phenolic resin finally forms a polymer chain glass carbon. The solid -phase carbonization structure of the phenolic resin generally presents the glass -state structure of the same -sex in the same sex. The flow state is inlaid structure. The resin is solidified before the formation of liquid -phase layers at high temperature, forming oriental carbon, and the other directional carbon compared with the heterogeneous carbon, the former contracted 90%, the latter contracted 5 %, The result forms high -strength dense carbon. When mixed with phenolic resin mixed with phenolic resin, inlaid structures will be formed in the interface of the carbonized tissue. The proportion is selected to present a complete inlaid structure with large combination of intensity, while thermoplastic phenolic resin will not increase the carbon rate.
