Knowledge related to the production of electric furnace magnesia carbon bricks; Laiwu Ge Jingshui, Shandong; the main components of a converter magnesia carbon brick electric furnace magnesia carbon bricks:; electric furnace magnesia carbon bricks are made of magnesia graphite as the main raw materials plus an appropriate amount of binder; 2. Introduction of the main raw materials used in the production of electric furnace magnesia carbon bricks: 1. Fused magnesite: natural magnesite, light burned magnesia sintered magnesia; 2. Graphite: a natural mineral with carbon as the main component. Yes; 3. Phenolic resin: a non-aqueous organic binder for refractory materials; classified according to heating properties structural forms, there are thermosetting phenolic resins thermoplastics; thermosetting phenolic resins
Knowledge of electric furnace magnesia carbon brick production
1. The main composition of electric furnace magnesia carbon brick:
The electric furnace magnesia carbon brick is a refractory product made of magnesia graphite as the main raw materials, plus an appropriate amount of binder, through high-pressure molding low-temperature heat treatment. Magnesium-carbon bricks for electric furnaces started in Japan were a new type of refractory product developed in the early 1970s. It is mainly used for working lining of converter, electric furnace, working lining of refining ladle for steelmaking.
2. Introduction of the main raw materials used in the production of electric furnace magnesia carbon bricks in our factory:
1. Fused magnesia: It is an alkaline refractory material made by melting natural magnesite ore, light burned magnesia sintered magnesia through an electric arc furnace. The main crystalline phase of fused magnesia is periclase, the melting point is 2800℃, it starts to sublime in vacuum at 1600℃, it starts to sublime in reducing atmosphere above 2000℃, the density is greater than 3.40g/cm3, the porosity is 0%-10 %, Mohs hardness 5.5, strong corrosion resistance to alkaline slag, stable chemical properties, no reaction weak reaction with various refractory materials except silica bricks at a high temperature of 1500°C. The appearance should be more obvious after complete melting crystallization, other magnesia impurities are allowed to be mixed.
2. Graphite: It is a natural mineral with carbon as the main component. It has the properties of high temperature resistance, heat conduction, electrical conductivity, lubrication, plasticity corrosion resistance. It is the main raw material for carbon-containing refractories. Graphite for refractory materials is mostly flake graphite, which is divided into high purity, high carbon, medium carbon, low carbon graphite according to the fixed carbon content. The color is iron black steel gray. Density is 2.09-2.23g/cm3, melting point is 3700℃±100℃ (in vacuum), high thermal conductivity, small expansion coefficient, small elastic modulus, good lubricity, good electrical conductivity, stable chemical properties, acid at room temperature , Alkali organic solvents do react, hard to wet with molten steel, have good corrosion resistance.
3. Phenolic resin: a non-aqueous organic binder for refractory materials. It is made by polycondensation of a mixture of phenol ( cresol, xylenol, resorcinol) formaldehyde ( sugar aldehyde) under the action of a catalyst. The main advantages are (1) high carbonization rate (52%); (2) good adhesion high strength of the formed body; (3) high bonding strength after firing; (4) hardening speed can be controlled at room temperature; ( 5) Less harmful substances, which can improve the working environment.
According to heating properties structural forms, there are thermosetting phenolic resins thermoplastic phenolic resins. According to product forms, there are liquid phenolic resins solid phenolic resins (granules powders). Classified by curing temperature, there are high-temperature curing types 130℃-150 ℃; there are medium temperature curing type 105℃-110℃; there is normal temperature curing type 20℃-30℃.
Thermosetting phenolic resin binder generally requires that the moisture in the aldehyde resin should be less than 1.8%, its viscosity changes with temperature, the viscosity decreases with the increase of temperature. In order to ensure proper viscosity, the use temperature should be controlled between 40-45°C. At the same time, there is the phenomenon that the viscosity changes with the storage time. The storage time is prolonged the viscosity changes greatly. If the storage period is too long, it will solidify cannot be used. Generally, the storage time is 30 days (in the warehouse) at high temperatures in summer longer in winter. The relative storage time of thermoplastic phenolic resin will be longer, the trapping time of the electric furnace magnesia carbon brick material with this combination can reach 30 days without affecting the molding viscosity, but a curing agent (Urotropine) must be added to ensure the dry strength.
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