Questions and answers on new technology of metallurgical resistant materials

How to form a stable slag skin protection layer on the surface of the blast furnace cooling wall to make the blast furnace energy saving and long life?

Answer: Blast furnace cooling wall is an important part of blast furnace structure. It can be divided into cast iron, cast steel, copper and hot side with copper, cold side with steel composite structure cooling wall. The surface of the cooling wall facing the inside of the blast furnace has smooth surfaces, concave and convex grooves, and other structural forms, but it is mainly concave and convex structure. The function of the concave and convex groove is to facilitate the insertion of the refractory protective layer and to facilitate the formation of a hanging slag protective layer on the cooling wall surface after the refractory is worn off.

The firebrick embedded on the surface of the cooling wall can effectively protect the cooling wall from the wear of the charge, and also form a thermal resistance in the furnace wall to reduce the heat dissipation energy of the furnace wall. However, the environment of the refractory material on the surface of the cooling wall is very harsh, and it has to withstand the erosion of slag, the wear of the charge, the erosion of the rising gas flow, the thermal shock of the temperature change under high temperature conditions for a long time, so it is gradually worn or washed away for a few months or a little longer.

Without the protection of refractory materials, the surface of the cooling wall will be exposed and directly subjected to the erosion and erosion of high temperature charge and furnace gas. At the same time, because there is no insulation of the refractory layer, the cooling water in the cooling wall will take away a lot of heat, resulting in a lot of heat loss, which is reflected in the production of high coke ratio and high energy consumption.

In order to prevent problems such as high energy consumption and the burning of the cooling wall, the blast furnace is generally regularly sprayed on the inner wall or pressed into the lining repair, the purpose is to try to build a new layer of refractory protection on the inner wall after the inner wall refractory is worn.

However, whether it is sprayed or pressed, the service life of refractory materials is still very short, generally half a year or a little longer to fall off. How to form a stable slag skin protection layer on the surface of the cooling wall is the key to solve the problem of energy saving and longevity of the blast furnace.

In order to solve the above problems, Beijing United Ronda developed a new patented product – pre-hanging slag skin protection layer, the material is synthetic slag skin material, made of refractory material and calcium silicate powder and metal steel fiber according to a certain proportion, so the wear resistance and strength is very high, and does not occur dovetail tank fracture, so that it can be covered on the cooling wall for a long time. It is equivalent to a layer of permanent pre-hanging slag on the cooling wall. It has the following technical characteristics:

First, it has high shear resistance, high wear resistance, high thermal conductivity and easy to hang slag.

The second is that it has the characteristics of high temperature resistance and corrosion resistance of ceramic materials, and the characteristics of high strength resistance to mechanical impact of metal materials.

Third, the integrity is good, the interior is not easy to be eroded, and the integrity of the refractory can be maintained.

Fourth, a large number of steel fibers in the pre-hung slag castable can play a good toughening effect, will not fall off as a whole, and will only slowly erode away.

Fifth, the thermal conductivity is very high, and a certain width of temperature gradient can be formed, so that the isocoagulant line of 1150 ° C is pushed into the furnace, which is conducive to slowing down the erosion and hanging slag.

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