JPH0647504B2 - Mud material for tapping of blast furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mud material for blast furnace tapping.

[Prior Art] The recent increase in the size of the blast furnace and the increase in the amount of tapping due to high-pressure operation make the conditions for using mud material extremely severe, and not only the conventional corrosion resistance and workability, but also the tapping depth. It is a very important issue how long it can be stabilized.

Currently, various blast furnaces have 1 to 4 tap holes in one furnace, and these tap holes are generally used alternately for tapping work, so the intervals of opening and closing of tap holes are the same. It is usually several hours at the pig iron, but depending on the operation, only two diagonal taps are used alternately for a week or more, and then the resting tap is used. There is also continuous tapping in which one tapping hole is continuously used due to the situation of (1) or a problem with a mud gun, in which case it is time to open and close the hole in about 1 hour. Due to the diversity of these operations, the characteristics required for mud materials are as follows.

In order to facilitate tap hole filling work with a mud gun,
It has the optimum viscosity and plasticity; the mud material after taphole filling has a short firing time and should be fired and sintered early; the sintering strength after firing does not fluctuate depending on the length of firing time, Easy hole work; Corrosion resistance to slag and hot metal, long-time deposition in the furnace, small expansion of tap hole diameter, stable tapping speed; filling tap hole The formed mud material is capable of forming and maintaining a stable depth due to its volume stability and rapid strength against rapid heating.

In order to provide the above-mentioned mud material for tapping of the blast furnace with its characteristics, various refractory raw materials, particle size constitutions, binders, etc. have been studied. For example, chamotte, loach, coke, and silicates containing clay as a main raw material, low-burning clay to high-burning clay alumina, fused alumina, silicon carbide, silicon nitride,
Alumina based mainly on coke and refractory clay is becoming mainstream.

At present, as the binder type, coal-based tar-based, petroleum-based, and resin-based solutions have been used.

These prior arts include, for example, JP-A-51-119709, JP-A-52-6717, JP-A-52-33907, and JP-A-52-62.
It is disclosed in JP-A-320, JP-A-52-62321, JP-A-52-92803 and JP-A-53-73214.

[Problems to be solved by the invention] In recent years, even for large-scale high-pressure blast furnaces, an operating goal of more than a dozen years has become a general goal for blast furnace life in recent years. As a result, blast furnace bricks are now under severe operating conditions. The life extension of the furnace depends on how to reduce the wear of the furnace wall brick around the lower part of the taphole, and the operation technology and the protection of the furnace wall by the mud material are important issues. The protection of the furnace wall by the mud material is not only for the purpose of closing the taphole, but also for controlling the hot metal and slag flow around the lower part of the furnace wall by extending the taphole depth.

Securing the expansion and stability of the taphole depth protects the furnace wall bricks around the taphole in the lower part of the blast furnace, can prolong the life of the furnace, and reduce the residual iron and residue in the tapping work, Operation can be controlled at a constantly low level of hot metal in the furnace, fluctuations in wind pressure can be reduced, and secondary damage due to equipment failure, etc. can be prevented, and stable operation and safety can be achieved. Can play a big role.

However, although the current mud material has been improved and improved, it was not possible to obtain a stable taphole depth that was sufficiently satisfactory for the movement of the contents in the furnace, the hot metal, and the violent flow of molten slag. The current situation is to reduce the inner diameter of the tuyere at the top of the taphole, close the tuyere, or widen the tuyere spacing.

These measures are not preferable because the air flow balance in the furnace is impaired from the viewpoint of stable operation. Therefore, the most important issue is to develop a mud material suitable for blast furnace operation technology and extend the tap hole depth.

Therefore, how to improve the corrosion resistance of the mud material, which occupies the most basic part among various factors that form the tap depth from the viewpoint of the mud material. In recent blast furnace operation, in order to efficiently produce reductive dissolution of iron ore, a method of adding lime and MgO-based raw material to self-fluxing sinter or pellets by pretreatment of iron ore is adopted, and the produced slag component ratio (% by weight) ) Is Si
O ₂ 34%, FeO 0.3%, Al ₂ O ₃ 14%, CaO 42%, MgO
5-10% slag basicity (SiO ₂ /CaO)≒1.2,
The melting temperature is as low as 1250 to 1300 ° C., and the increase of the alkaline earth metal such as MgO lowers the viscosity of the produced slag and promotes the melting rate of the mud material. Further, FeO still contains about 0.3% in the measurement outside the furnace, and it is presumed that FeO is more in the vicinity of the tap hole in the furnace.

Therefore, as the MgO content in the slag increases, the mud material used is chamotte, raw stones to high alumina, and the materials are SiO ₂ —SiC—C to SiO ₂ —Al ₂ O ₃ —SiC. −
It has been converted to C-type, and further converted to Al ₂ O ₃ -SiC-C-type material to which silicon nitride or a sintering agent (metal silicon or metal aluminum) is added. Corrosion resistance is still insufficient, and it is essential to develop a mud material with high corrosion resistance in order to stabilize the taphole and maintain the depth.

Therefore, the object of the present invention is to improve the stability of operation and tapping work and the protection of blast furnace wall bricks by maintaining a particularly important taphole depth, which is particularly important among the characteristics of mud material. It is an object of the present invention to provide a mud material for a blast furnace tap hole that can extend the life of the furnace.

[Means for Solving the Problems] That is, according to the present invention, 35 to 50% by weight of spinel containing MgO.Al ₂ O ₃ as a main constituent, and the balance of coke,
The present invention relates to a mud material for a spinel blast furnace taphole, which is composed of a refractory raw material selected from the group consisting of silicon carbide, silicon nitride, clay, pitch and a sintering agent, and an organic binder.

[Operation] The mud material for taphole of the blast furnace of the present invention is particularly suitable for MgO and FeO components among slag components CaO, SiO ₂ , Al ₂ O ₃ , MgO and FeO existing near the taphole in the furnace. By using spinel (MgO ・ Al ₂ O ₃ ) mineral as the main raw material, conventional Al ₂ O ₃ -SiO ₂
Quality, Al ₂ O ₃ quality raw materials inevitably generate low melting point minerals,
It has the best corrosion resistance against the slag by solving the problem of insufficient corrosion resistance.

Conventionally, the main refractory aggregate of the mud material was chamotte, silicate ore, loastone, natural alumina, fused alumina, sintered alumina, etc., but the mud material for blast furnace taphole of the present invention is the main aggregate part. Alumina spinel (MgO ・ Al ₂ O ₃ ) mineral produced by electro-melting or sintering method is used for low melting point compound to alkaline earth metal oxides (CaO, MgO) and FeO in slag component. It is difficult to generate.

Incidentally, the well-known CaO-SiO ₂ -MgO system from the phase diagram, CaO-SiO
₂ -Al ₂ O ₃ system, SiO ₂ -Al ₂ O ₃ -MgO based, CaO-Al ₂ O ₃ -MgO
System, Ca ₂ Al ₂ SiO ₇ -Al ₂ O ₃ -MgAl ₂ O ₄ system, Ca ₂ Al ₂ SiO ₇ -CaAl
₂ SiO ₈ -MgAl ₂ O ₄ system, FeO-MgO system, FeO-Al ₂ O ₃ system, spinel (MgO
_The preferred direction is to use ₂ O ₃ ) minerals as aggregates.

The spinel (MgO.Al ₂ O ₃ ) mineral, which is the main raw material for the mud material for blast furnace tapping according to the present invention, has a composition ratio of MgO and Al ₂ O ₃ of MgO10.
It is effective in the range of up to 45% by weight and 90 to 55% by weight of Al ₂ O ₃ . If less than 10% by weight of MgO in the spinel minerals,
Even if the mixing ratio of the mud material is increased to 50% by weight, there is no difference from the raw material of alumina alone, and there is no effect. Further, if MgO exceeds 45% by weight, it may be ineffective due to the influence of SiO ₂ , Al ₂ O _{3 and the} like in the slag component, or conversely the melting loss may increase.

The mixing ratio of the spinel mineral to the mud material is effective in the range of 35 to 50% by weight with respect to the spinel raw material produced by the electrofusion method or the sintering method. The mixing ratio of the spinel mineral is as described above, but the range of 5 to 20% by weight is effective for the spinel raw material having a particle size of 75 μm or less. The mixing ratio of the spinel raw material of the above particle size is 20
If the content is more than wt.%, The amount of particles of 75 μm or less in the composition ratio of the mud material becomes too large, and the amount of the binder added increases due to the workability of filling the mud gun, resulting in a negative effect on the characteristics of the mud material and the corrosion resistance. Combining a spinel grain size of 3 mm or less with other raw materials such as coke, silicon carbide, clay, pitch, silicon nitride, and a sintering agent (metal silicon, metal aluminum, etc.) is effective up to a spinel blending ratio of 50% by weight or more. Then, it becomes unsuitable because the characteristics of the mud material cannot be satisfied due to other raw material composition.

As the organic binder, a coal-based binder, a petroleum-based binder, a resin-based binder or the like can be appropriately selected and used.

[Example] The mud material for taphole of blast furnace of the present invention will be further described with reference to the following examples.

Examples Table 1 below shows the quality of the raw materials used in the examples, and Table 2 shows the blending ratio of the raw materials.

The kneading temperature at the time of kneading with a lower mixer according to the mixing ratio shown in the above examples is 40 to 50 ° C when tar is used as a binder, and 30 to 40 ° C when phenol resin is used. The time was 25 minutes in each case. Specimens for measuring the characteristic values in Table 2 are the above-mentioned kneaded clay that has been pressure molded at a molding pressure of 150 kgf / cm ² .

Corrosion resistance comparison of Table 2 is A method: 155 by high frequency induction furnace
0 ℃ x 3 hours, 10kg pig iron and blast furnace slag 3 as erosion agents
This is a comparative test with replacement of 00g × 6 times. Also, method B:
It is a comparative test when the blast furnace slag as an erosion agent was replaced by 1200 g × 3 times (reactor rotation speed 4 rpm) in a rotating arc furnace at 1550 ° C. for 3 hours. Erosion index is a corrosion resistance comparison test A
The method is the maximum erosion depth, and the B method is the erosion volume.
This is a comparative value when 00 is set.

The mud material for blast furnace tapping according to the present invention, which uses spinel as a refractory aggregate, is significantly improved in corrosion resistance by 1.1 to 1.9 times compared with the above-mentioned recent blast furnace slag. I was able to.

In addition, when the mud material for blast furnace tapping of the present invention was tested in an actual machine with a large blast furnace of 4500 m ³ , the tapping time was 1.1
.About.1.3 times, the depth of tap hole was extended by 100 to 400 mm, which was remarkably improved in terms of stable operation of the blast furnace.

[Advantages of the Invention] The mud material for blast furnace taphole of the present invention is made of spinel (MgO.Al).
₂ O ₃ ) Minerals are the main raw materials, and prevent the deterioration of corrosion resistance due to the slag components existing near the taphole in the furnace, namely CaO, Al ₂ O ₃ , MgO, and FeO, especially MgO and FeO components. As a result, it is possible to provide a mud material for a blast furnace tap hole having excellent corrosion resistance against the slag.

Claims (1)

[Claims] 1. A refractory material selected from the group consisting of 35 to 50% by weight of spinel containing MgO.A ₂ O ₃ as a main constituent, and the balance consisting of coke, silicon carbide, silicon nitride, clay, pitch and a sintering agent. A mud material for spinel blast furnace taps, which is composed of a raw material and an organic binder.