Influence of construction at low temperature in winter on properties of refractory castables for heating furnaces

January 17, 2022

    Heating furnace is an important thermal equipment for heating billets in rolling mills. At present, during the construction of the heating furnace, the refractory castable has the advantages of short construction period, good thermal insulation effect and high overall strength, so it is widely used in various parts of the heating furnace lining. During construction in winter, it is generally required that the stirring water temperature should be controlled at 15~35℃, and the curing temperature should be strictly controlled above 5℃. Especially in the northern region, the temperature in winter is basically below zero, and the ambient temperature of some construction sites is too low, resulting in poor fluidity of refractory castables and prolonged solidification time. Seriously affect the construction quality and construction progress. Therefore, during the construction of refractory castables in winter, effective thermal insulation measures must be taken, and the temperature of the construction environment must be increased to above 5 °C to ensure that the refractory castables are not frozen and the construction process can proceed smoothly.

 

    The production and maintenance test of refractory castable samples were carried out under the ambient temperature of 5 ℃, and it was found that the low temperature casting construction has a relatively great influence on the refractory castable. Combined with the technical guidance practice on the construction site, the following impacts are summarized:

 

(1) Construction at low temperature, it is difficult to stir the refractory castable evenly, thus affecting the forming of the material after construction.

 

(2) Construction at low temperature, during the stirring and discharging process of refractory castables, the fluidity becomes smaller, and it is easy to form voids during pouring.

 

(3) The strength of the refractory castable will become lower when it is constructed at low temperature, and it is easier to form a loose state after being frozen, and it is easy to fall off and fall off when the mold is removed.

 

(4) During construction at low temperature, the free water in the refractory castable will peel off due to the expansion of the icing volume.

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