Scientific analysis of castable “appears white hair” phenomenon and effective solution

Castable material in using process often can see high alumina cement castable appeared on the surface of hanging “frost”, “long hair” “powder” “powder” phenomenon. In the common refractory castable surface and water to have loose gelatinous precipitate. These “frost” is because the cement particle surface castable not hydrated in water, forming supersaturated solution, then precipitated alumina sol and hydrated calcium aluminate induced. In fact, “white box” is not affect castables performance, but too much can cause rough skin on the construction, affecting the appearance.

Reason of castable long white: containing alkali refractory raw material, such as calcined alum refractory aggregate in, calcination sticky superior, as calcium aluminates cement castable. All kinds of powder, such as a variety of fine powder, silicon powder and kyanite; there are also contains alkali additives, such as reducing agent, coagulant, explosion-proof toughness. These materials often contain a small amount of alkali, the alkali, some can be dissolved in water, especially the dispersing agent of alkali, almost all into the wood. These “base” by capillary hole to the hardening decent migration, arrives at the table and then, the formation of carbonate and C02 reaction in the air.

Solution for casting material surface “frost” phenomenon:

1. Choosing low alkali content of refractory materials;
2. As soon as possible out of the water, drying, carrier to eliminate sodium alkali, stranded in the construction of the body, not to migrate to the surface.
3. The castable airtight, covered with plastic film, thereby preventing the moisture with alkali to migrate to the surface.
4. Improve the refractory castable viscosity and rapid hardening (reduce sodium migration velocity).
5. Strengthen quality control, strict control of water, to prevent too much water.

The method applies to prolong the life of ladle refractory castable in our country

Extended service life, can save money and bring benefits. Since the conditions of use of extremely harsh refining ladle slag line site and cause serious erosion of the containment wall parts ahead of

refractory castable become so damaged the main reason for its life. Quality of life of refractory castable ladle also plays a decisive role.

Ladle castable ladle development to improve life, to overcome the shortcomings of the brick type play a good effect. The current development has a water glass ladle castable

combination of aluminum and magnesium, aluminum - spinel castable, but with the development of the outer casting and refining technology, the former has been unable to meet the current development of many steel smelting technology needs.

In industrialized countries, the popular use of aluminum - spinel castable. Although this material long life, but at the tabular alumina, alumina and industrial grade synthetic magnesia spinel, alumina cement and other raw materials, the price is expensive. Most of our current domestic economic strength of steel without the use of expensive high-end ladle castable, however, China has abundant bauxite resources and using both synthetic alumina spinel raw materials, these materials are developed ladle castable suitable for China.

Refractory for electric arc furnace lid

EAF uses A1203 65% -85% alumina brick masonry lid, the special needs of the site is also used tabular alumina brick (with a plate Al20390% -100%), but the price is expensive, silica brick is about 10 times higher 31V or thermal stress relief lid damaging effects of aluminum bricks, high alumina brick firing using phosphate bonded alumina bricks do not burn with white masonry made good use of effects. Some (HP) in high power electric furnace cover, the main use of high alumina bricks (about 80% Al2 03) and chemically bonded magnesia-chrome brick (Mg0> 65%, Cr2 037% _15%) Consolidated masonry furnace cover. High power (UHP) electric cover using mullite corundum brick, the brick main feature is a good thermal stability, resistance to high temperature load-deformation ability, it just to meet the requirements of the lid refractories, MK-80, No. MO corundum bricks,

is fused corundum and fused mullite particles strengthen the structure of products. 50t UHP EAF for cover, stainless steel and bearing steel smelting life increased by 25% -35% higher than magnesia-chrome brick roof.

High alumina brick lid. Alumina brick masonry furnace lid began in the late 1950s. At that time the use of high alumina brick lid (Ak 0365% -80%) increased by 4 times higher than silica brick lid life. Firing alumina bricks (A \ 2 03 80 16) and phosphate binding does not burn alumina brick (Al2 03 80% -85%) and mullite brick firing or not firing phosphate binding mullite brick, they have in common is an excellent thermal shock resistance. The life of the early 1960s, the lid has reached about 200 furnaces.