With the continuous optimization of blast furnace structure and new furnace lining materials continue to be introduced and used, the level of control and operation has been improved, so that the life of the blast furnace is continuously extended, and it is expected that the life of the blast furnace will reach more than 20 years.

The long life of blast furnace is an important guarantee of high efficiency and low consumption of iron and steel enterprises. With the development of blast furnace iron-making technology, the use of refractory materials for furnace lining has become increasingly demanding, and the requirement of long life of blast furnace has posed a greater challenge to refractory materials. Refractories in the bottom part of the blast furnace cylinder store hot iron for a long time, and it is difficult to replace the broken lining in time during the continuous operation of the blast furnace, which determines the life of the blast furnace for a generation of service. Long-term practice shows that high-quality refractory materials and reasonable lining structure is the basis for the long life of the blast furnace. Therefore, it is important to analyze the erosion mechanism of blast furnace refractory lining and take effective measures to improve the lining structure and material to extend the life of blast furnace.

A new type of corundum-based refractory for blast furnaces was developed by drawing on the design ideas of artificial graphite-based carbon bricks, and the effect of artificial graphite addition on the performance of corundum-based refractories was systematically studied in order to obtain good microporosity and thermal conductivity while maintaining high erosion resistance. From the research work, the following conclusions can be drawn.

(1) The high thermal conductivity masonry method of furnace cylinders tends to cause excessive heat dissipation from the furnace cylinder iron and excessive thermal stress on the refractory at the working surface of the furnace cylinder in the insulated masonry method. When the furnace bottom cylinder parts use multi-layer masonry structure, the refractory thermal conductivity from inside to outside from 10W/(m-K) to 40W/(m-K) gradually increase is conducive to the construction of soft molten layer in the furnace bottom, while the cylinder parts are difficult to adjust the temperature field to make the iron in the working surface fully cooled, still need to optimize the lining material to achieve the goal of long life.

(2) The addition of artificial graphite helps to improve the thermal conductivity of the electrocalcined coal-based carbon bricks and reduce the anisotropy of thermal conductivity, but it affects the resistance of carbon bricks to ferrous dissolution; the analysis by support vector machine modeling shows that the artificial graphite content has a more obvious effect on the improvement of thermal conductivity; with the help of this modeling method, the prediction fitting formula for the thermal conductivity of carbon bricks is obtained, which has high accuracy and can be used for the optimization and prediction.

(3) By adjusting the critical particle size of the artificial graphite aggregate and using in situ reaction technology and particle compacting technology, an encapsulation structure of alumina and silicon carbide whiskers can be constructed on the surface of the aggregate, which can improve the resistance to iron erosion and microporosity of the artificial graphite-based carbon brick.

(4) Using equal amounts of blueschist, rhodochrosite and silica fines with high temperature reactivity to replace alumina, mullitization reaction can occur during the heat treatment of carbon bricks. The process of mullitization of tristone facilitates the generation of silicon carbide whiskers, which further optimizes the microporous properties of the artificial graphite-based carbon brick specimens. In the cross-sectional comparison of the three stones, the reaction temperature required for blue crystallite is lower.

(5) The artificial graphite-based carbon brick with titanium dioxide micronized by 1400℃ buried carbon roasting can generate titanium carbon nitride phase in situ and is beneficial to promote the growth of silicon carbide whiskers. When 6% TiO2 is added externally, its average pore size is less than 100 nm, and the pore volume less than 1 μm reaches 90%, and the thermal conductivity at room temperature is as high as 53.43 W/(m-K). Anti-iron erosion experiments show that this in-situ formation of titanium carbon nitride carbon brick specimens are conducive to the construction of a high viscosity layer similar to that formed by the titanium ore guard method, reducing the waste of titanium resources caused by the titanium ore guard.

(6) The use of artificial graphite aggregates with particle size ≤1 mm instead of the corresponding brown corundum aggregates and the addition of silica micronized powder and bituminous powder on the basis of traditional ceramic cups helps to optimize the microporosity and thermal conductivity of the specimens while maintaining high erosion resistance. This new refractory material can be used not only to resist scouring and penetration of iron in the furnace cylinder, but also to adjust the thermal conductivity by varying the artificial graphite aggregate content and to build a soft melt layer in the furnace bottom.