②Fall off

Shedding is also one of the common problems in the application of aluminum-magnesium castables. It is the result of uneven stresses in the castable. For example, when Al2O3 and MgO in the matrix are used, the MA spinel is formed by the action of high-temperature molten steel, which is accompanied by a large volume expansion. If the response is very severe, it is easy to attack the structure under the impact of molten steel. Fall off. Therefore, in the matrix to manipulate this spinel reaction, it is necessary to control the content of each component, especially the content of MgO is very important, if the MgO content is too high, in addition to the spinel reaction, it itself is larger The rate of line change, the volume expansion, will also grow off. Generally, the content of magnesia is controlled at about 10% (mass fraction), and the effect is better.

The pouring construction also has an effect on the occurrence of shedding. In this respect, it is necessary to strictly control the amount of water added and achieve uniform oscillation together. If the amount of water added is too large, the vibration of the green body will be uneven, and the porosity will be added. When used, it is easy to present the phenomenon of steel drilling, which causes the wall to fall off.

③Slag line corrosion

Because the composition of the steel slag is disorderly, it is easy to chemically react with the castable, so that the castable of the slag line is prematurely damaged, and then the slag line and the wall can not be used simultaneously, which is also a problem encountered in practical use. Under the premise of not adding a large amount of capital, the following methods are used;

(1) Specially manufactured slag line material for pouring of slag line parts. The material of the slag line material is improved to a grade. For example, the alumina powder is made of high quality high alumina bauxite clinker with ω (Al2O3) = 86% and bulk density > 3.2g·cm-3;

(2) Participate in the partially pre-formed aluminum-magnesium spinel in the slag line and select a high MgO ratio, which can improve the ability to resist alkaline slag;

(3) reduce the amount of active silica fume, and control it at about 1.0% (mass fraction);

(4) Strictly control the amount of water added during the pouring and oscillate evenly. After these measures, the slag line and wall life are basically synchronized.

(1) Retarding skill is one of the key skills in the construction of aluminum-magnesium castables. It is necessary to participate in the retardation agent such as lignosulfonate according to the time and environmental temperature changes, so that the coagulation time can satisfy the demand of pouring construction. .

(2) Participation in part of the super large aggregate and zircon powder in the castable is very beneficial to the occurrence of cracking.

(3) The slag line material is selected from high MgO ratio and participates in some pre-formed aluminum-magnesium spinel powder, which can improve the slag corrosion resistance of the slag line.

(4) During pouring construction, strictly control the amount of water added and oscillate evenly, which is of great significance to the service life of progressive castables.