The thermal insulation of the permanent layer of the ladle has been a problem for many years. The permanent layer behind the working layer, from the use of clay bricks to high alumina bricks, to the currently used [b]ceramic fiberboard[/b] or high alumina castables, Since the thermal conductivity is high, the temperature of the outer wall of the ladle remains high. The material testing and industrial tests for the permanent lining of the ladle are carried out below. The comparison test of the characteristics of the thermal insulation material of the permanent layer of the ladle (Anshan Iron and Steel Technology Center) is as follows:
At present, Anshan Iron and Steel’s ladle has achieved full cover insulation and online baking. The heat dissipation method of molten steel in the ladle is mainly through the heat transfer of the tank wall. According to the heat transfer theory, the overall heat transfer effect of the entire tank wall depends on the thermal conductivity of the ceramic fiber board, which is the insulation material. A reasonable choice of insulation material with a smaller thermal conductivity can not increase or even reduce the thickness of the cladding wall. , Greatly improve the thermal insulation effect of the ladle.
At present, the existing technology is to use refractory fiber castable and thermal insulation [b] ceramic fiber board material for the thermal insulation layer of the ladle wall. Yes: the refractory fiber cotton is directly mixed into various unshaped refractory bulk materials after being crushed. According to the different refractoriness, different types of matrix materials and binders are selected, and the broken refractory fibers are added to these bulk materials. After stirring, adding water (the amount of water added reaches 40%-90%, the shrinkage is large) and casting molding, the broken refractory fibers are not well dispersed, and most of them are in the form of cloud flakes or clusters of uneven size. Although the refractory fiber castable is light-weight and heat-insulating, the castable has very low strength and large shrinkage, and it does not really exert all the properties of refractory fiber for heat insulation. In other words, after the refractory fiber is mixed with the refractory bulk material, the porosity of the fiber is mostly destroyed, and many places are filled with refractory slurry. The shape of a material distributed in the product directly affects the overall strength of the product and the best thermal insulation effect.
In order to reduce the temperature of the outer wall of the ladle, Panzhihua and Baotou Iron and Steel Co., Ltd. built a layer of refractory fiber hard [b]ceramic fiberboard[/b] (compressive strength 0.6MPa) between the permanent lining and the cladding. The effect is good, due to the dew loss and steam corrosion of the insulation board (the steam generated every time the working layer is replaced), the intensity is reduced. The unsatisfactory service life directly affects the strength of the permanent layer.