Slag Resistance Test of MgO-CaO Refractory

The erosion mechanism of MgO-CaO refractories with different compositions in converter slag system was tested by the method of slag-absorbing load deformation, and the mechanism of slag-absorbing erosion was analyzed by chemical analysis, microscope and electron probe.

The slag-absorbing load deformation method can indirectly reflect the damage degree of refractory materials in the process of slag-absorbing, and come up with an intuitive concept of magnitude of the container containing oxidizing slag, so as to find a suitable method to choose refractories.

It is found that the porosity has obvious influence on the deformation rate of slag samples, and the influence of different refractories on different slag is also different.

Reducing the porosity of refractory has a good effect on the corrosion resistance of vanadium and titanium slag. Mgo-cao refractory with higher MgO content is selected as lining, which is better for converter containing vanadium and titanium slag.

Through the experimental observation of slag invading refractories, it is concluded that the main way of slag penetrating into refractories is along the capillary channel, so reducing the porosity of refractories can also improve the slag resistance. With the increase of the invasion depth, the larger the deformation rate of the sample, that is, the larger the amount of liquid phase in the sample, the more severe the structural damage of the refractory.

Therefore, the larger the liquid phase formed by slag and refractory under the action of high temperature, the more serious the damage of refractory. Through comparative study, it is found that MgO is less soluble in the liquid phase of vanadium and titanium slag, indicating that MgO is more able to withstand the erosion of vanadium and titanium slag. Therefore, MGO-Cao refractory material with higher MgO content is selected, which has better resistance to vanadium and titanium converter lining.

In addition, at high temperature, chemical reactions occur between converter slag and refractory materials, resulting in a large number of high melting point compounds, and the precipitation of these compounds will directly hinder the forward penetration of molten slag into refractory materials, and the damage to the structure of refractory materials will be reduced, and the deformation rate of the sample will be smaller.

Therefore, the formation of these high melting point compounds or solid solutions will reduce the degree of structural damage of refractory.

In general, the erosion experiment of steel slag on MgO-CaO refractory was carried out by slag absorption and load deformation method. The erosion mechanism was discussed by experiments, microscope observation and electron probe analysis.

And draw the following conclusions:

(1) As the porosity of the material decreases, its resistance to slag erosion increases.

(2) With the increase of MgO content in MGo-Cao refractory, the corrosion resistance of steel slag is enhanced, especially for vanadium and titanium slag.

(3) The erodibility of converter slag containing vanadium and titanium is greater than that of converter slag.

(4) It is better for vanadium and titanium steel slag to use MGo-Cao refractory with high MgO as furnace lining.

It is feasible to study the erosion of refractory materials by slag absorption by load deformation method. But this method can not determine the dissolution rate of refractory in slag.