High-heat-conductivity long-life blast furnace hearth and brick lining building method

Abstract

The invention discloses a high-heat-conductivity long-life blast furnace hearth and further provides a brick lining building method of the high-heat-conductivity long-life blast furnace hearth. The high-heat-conductivity long-life blast furnace hearth comprises a furnace shell, a cooling wall and brick linings which are arranged sequentially from outside to inside. On the lower portion of the hearth, the lower-middle portion of the hearth, the middle of the hearth, the upper-middle portion of the hearth and the upper portion of the hearth, the brick linings comprise small-block carbon bricks,carbon ramming material layers and large-block carbon bricks which are arranged sequentially; and at the top of the hearth, the brick linings are formed by building a plurality of small-block carbon bricks. According to the high-heat-conductivity long-life blast furnace hearth, cracking of the hearth brick linings due to thermal stress and erosion damage caused by harmful elements through cracks can be avoided, circulation erosion of molten iron can be further resisted effectively, thus the erosion damage to the hearth is relieved, and the service life of a blast furnace is prolonged.

Description

technical field [0001] The invention belongs to the technical field of ironmaking, and in particular relates to a method for building a hearth of a blast furnace with high thermal conductivity and a long service life and a brick lining. Background technique [0002] The blast furnace is a high-temperature, high-pressure large-scale reaction vessel used for iron ore reduction and smelting, and it is also the leading process for the production of molten iron in my country. From top to bottom, the blast furnace structure can be divided into throat, furnace shaft, furnace waist, furnace belly and furnace hearth. The furnace hearth is the part where molten iron and slag are contained, and the periodic slag and iron discharge of the blast furnace is completed. It is also the part that restricts the life of the blast furnace. Once the hearth is severely corroded and burned through in key parts, the furnace needs to be shut down for overhaul, and the first generation of blast furnac...

AI Technical Summary

Problems solved by technology

[0009] The above reaction is accompanied by a large volume expansion (30% to 50%), which leads to damage and fracture of the brick lining.

When the above-mentioned fractures or even hearth ring cracks exist in large carbon bricks, the breaks or ring cracks will become the radial heat insulation layer of the hearth. The erosion rate is greatly accelerated, and at the insulating layer, due to its lower temperature, it will also cause harmful elements to deposit and erode more easily in this area, which will lead to further expansion of the eroded area and the fractured area. A vicious circle will be formed, which will greatly shorten the life of the hearth

[0010] (2) After the smelting intensity of the blast furnace is increased, the molten iron circulation intensifies the erosion of the hearth carbon brick side wall

At present, for blast furnaces that use double taps to alternately tap iron, the tapping flow rate is about 10t / min. The larger tapping flow rate has a great impact on the circulation scour of the side wall of the hearth, especially when the hearth uses small pieces of carbon bricks. (see figure 2 , At present, most of the small carbon bricks used in domestic blast furnaces are NMA and NMD small carbon bricks from UCAR in the United States. The size of the carbon brick is small, so that there are too many brick joints in the circumferential direction of the hearth, and the above brick joints will become the weak part of the hearth brick lining to resist the circulation of molten iron

In addition, small carbon bricks are limited by the formula and molding process (small carbon bricks generally use electrode graphite as the main raw material, and electrode graphite has poor erosion resistance to molten iron erosion, and has not been sintered at a high temperature above 1300°C after hot pressing), Its own resistance to slag and iron erosion is also weaker than that of large carbon bricks

Therefore, when small pieces of carbon bricks are used in the lower part of the hearth, it is easy to cause erosion and iron infiltration under the circulation of molten iron in the hearth. When the cooling intensity is insufficient, it will also cause rapid erosion of the hearth carbon bricks. Furnace burn-through accidents will occur within 2 to 3 years

[0012] (3) The unreasonable structure of the hearth brick lining increases the thermal resistance and accelerates the erosion rate of the hot surface of the carbon brick

However, when using the traditional method of masonry, because the carbon ramming material is close to the cooling wall, its actual temperature is between 40°C and 50°C, and due to poor consolidation, the actual thermal conductivity is <10W / m·K

Therefore, the carbon ramming material layer becomes a heat insulation layer with low thermal conductivity in the radial direction of the hearth, which seriously hinders the heat transfer from the inside of the hearth to the outside, which not only prevents the stave from playing the role of enhanced cooling, but also leads to The temperature of the hot surface of the carbon brick is too high, exceeding the safe service temperature, which will accelerate the erosion and damage of the hearth brick lining and shorten the life of the blast furnace

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