Blast Furnace Refractory of High Quality

With the progress of the steel industry in various countries in the world, the blast furnace is developing towards large-scale, high-efficiency and longevity. And gradually adopt new smelting technologies such as oxygen-enriched coal injection, high air temperature operation, high pressure furnace top and so on. The working conditions of the blast furnace lining have undergone major changes, and its service life has been reduced more, generally only 5 to 6 years. Especially in the lower part of the blast furnace body, furnace waist and furnace belly, the refractory lining’s service life is much shorter. In order to adapt to this development, refractory materials for blast furnaces have also undergone major changes. New long-life, high-efficiency refractory materials have been gradually applied, and the life of blast furnaces has gradually increased.

Refractories Lining of Blast Furnace

Refractory for lining of blast furnace

The refractory materials commonly used in lining of blast furnace are mainly clay refractories, high alumina, aluminum carbon, silicon carbide, corundum, carbon and graphite.

The blast furnace shell is lined with a layer of refractory bricks with a thickness of 345 to 1150 mm. The purpose is to reduce the heat dissipation of the furnace shell. At the same time, cooling equipment is installed in the refractory bricks to prevent the deformation of the furnace shell. The damage mechanism of brick lining in each part of blast furnace is different. In order to prevent the shortening of the blast furnace service life from the damage of partly brick lining. Different refractory lining must be selected according to factors such as damage, cooling and blast furnace operation,etc.

Traditionally, high-grade fire clay bricks and super-high-grade fire clay bricks are used for the hearth and bottom. The refractory bricks’ damage of this part is caused by the gradual melting loss. Due to shrinkage and unqualified bricklaying, in the past, the blast furnaces frequently suffer major burn-through accidents. Therefore, most of the blast furnace hearth and bottom use carbon refractory materials, which can solves the problem of furnace bottom burn-through.

Fire Clay Bricks

There are three masonry types of refractory bricks lining at the bottom of the blast furnace.

(1) All the surrounding, upper and lower parts of the blast furnace bottom are all built with carbon bricks.

(2) Carbon bricks are used for the periphery and upper part of the furnace bottom, and clay bricks or high aluminum bricks are used for the lower part.

(3) Carbon bricks are used around and under the furnace bottom, and clay bricks or high aluminum bricks are used for the upper part.

The bottom of the blast furnace built by the latter two methods is also called the comprehensive bottom. And the design thickness of the furnace bottom has a tendency to thin. Reduced from 0.5d right to about 0.3d, or 1/4 thickness of furnace inner diameter. d is the diameter of the hearth. The disadvantage of carbon bricks is that they are susceptible to air, carbon dioxide, water vapor, and alkali metals.

The hearth, especially the brick lining at the bottom of the furnace body, is easily damaged due to wear, thermal stress, chemical attack, etc. When the blast furnace with cooling stave was put into production for about two years, the brick lining under the furnace body will almostly be eroded.

The brick lining on the upper part of the furnace body and the throat of the furnace. It is required to use materials with abrasion resistance and thermal stability. Clay bricks are suitable.

After the hearth brick lining is eroded, the production is maintained by "slag skin".

Characteristics of High Quality Refractory Materials for Blast Furnace

According to the operating conditions and erosion characteristics of the blast furnace lining, refractory materials are required to have:

(1) Good high-temperature performance and good thermal stability under long-term high temperature.

(2) The strength under normal temperature and high temperature is higher, and the wear resistance is better.

(3) High density, good thermal conductivity, low apparent porosity, and small shrinkage at high temperature.

(4) It can resist the violent erosion and erosion of hot metal, molten slag, blast furnace gas and furnace dust under high temperature and high pressure.

(5) The external dimensions of refractory bricks are accurate, which can ensure that the brick joints meet the specified requirements.

At present, there are many varieties of refractory materials for blast furnaces. Clay bricks or high aluminum bricks with excellent performance are generally used in the upper and middle parts of the furnace body. Special refractory materials such as carbonaceous products, silicon carbide bricks, mullite bricks, and corundum bricks are used for the lower part of the furnace body, furnace waist and furnace belly. Especially the recently developed silicon carbide bricks have been successfully applied in blast furnaces.

At the same time, other unshaped refractory materials have also been widely used. High-quality silicon carbide refractory materials have become attractive new refractory materials in recent years.

Silicon carbide refractories have good high temperature strength, high thermal conductivity, and low coefficient of thermal expansion. And good thermal shock resistance, alkali corrosion resistance, oxidation resistance, slag corrosion resistance and high temperature wear resistance and other excellent properties. It has been widely used in industrial sectors such as steel, nonferrous metallurgy and ceramics.

SiC Refractory Bricks

In the process of using refractory bricks, it is necessary to use refractory mortar of the same material to complete the masonry.

Rongsheng Refractory Manufacturer

As a specialized refractory manufacturer, Rongsheng provides high-quality refractory services for various thermal equipment. If you want to obtain high-quality refractory materials for blast furnace, please leave your specific needs and project conditions on our page. Our experienced sales engineers will provide you with suitable refractory materials according to your specific needs. We have now newly established our monilithic refractory, refractory castable production workshop, which specializes in the production of refractory castable products. Rongsheng has rich production and sales experience, as well as advanced production equipment. We chose Rongsheng's refractory materials, and we will not disappoint you.