JPH03279271A - Mud material for iron spout in blast furnace - Google Patents

Abstract

PURPOSE:To improve corrosion resistance to slug stagnating in the vicinity of an iron spout in a furnace by incorporating a spinel, a specific refractory raw material and an organic binder into the subject mud material. CONSTITUTION:5-50wt.% spinel containing 10-45wt.% MgO and 90-55wt.% Al2O3 as principal components is mixed with <=50wt.% refractory raw material selected from coke, SiC, Si3N4, alumina, clay, pitch and sintering agent (e.g. metallic Si) and organic binder (e.g. phenolic resin) to afford the aimed mud material.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a mud material for a blast furnace taphole.

[Prior art] The recent increase in the size of blast furnaces and the increase in the amount of tapped iron due to high-pressure operation has made the conditions for using mat materials extremely severe, and not only the conventional corrosion resistance and workability, but also the need to improve the tap hole depth. A very important issue is whether it can be kept stable for a long time.

Current various types of blast furnaces have 1 to 4 tapholes in one furnace, and these tapholes are generally used alternately during tapping operations, so the intervals between opening and closing of the tapholes are the same. Normally, it is a few hours at the taphole, but depending on the operation, only two diagonal tapholes are used alternately for more than a week, and then the idle taphole is used, or the taphole is There is also continuous tapping where one taphole is used continuously due to circumstances such as mud gun trouble, etc. In such cases, the hole may have to be opened and closed every hour or so. Due to the diversity of these operations, the following characteristics are required of mat materials.

■To make it easier to fill the iron outlet with a mud gun,
It must have optimal viscosity and plasticity; ■The mat material after filling the taphole requires a short firing period, and should be fired and sintered at an early stage; ■The sintered strength after firing does not fluctuate depending on the length of firing time. , Easy drilling work: ■ Corrosion resistance against molten slag and hot metal, long-term deposition in the furnace, minimal expansion of the tap hole diameter, and ability to maintain stable tapping speed: ■ The mat material filled in the pigtail hole can form and maintain a stable depth due to its volume stability against rapid heating and early strength.

In order to provide the above-mentioned mat material for the blast furnace taphole with such characteristics, various refractory raw materials, particle size refinements, binders, etc. have been studied. For example, silicates based on chamotte, loite, coke, and clay, alumina with low to high clay, fused alumina, silicon carbide, silicon nitride, coke, and alumina based on fireclay are mainstream. It is becoming.

Currently, as a type of binder, coal-based tar is mainly used, but petroleum-based and resin-based solutions have also been used.

These prior arts include, for example, JP-A-51-119709, JP-A-52-6717, and JP-A-52-339.
No. 07, JP-A-52-62320, JP-A-Sho 5
It is disclosed in JP-A-2-62321, JP-A-52-92803, JP-A-53-73214, and the like.

[Problems to be solved by the invention] In recent years, even for large high-pressure blast furnaces, it has become common to aim for a blast furnace lifespan of several years, and rather than simply extending the lifespan, significant technological innovations have been made in the operations. As a result, blast furnace body bricks are also being used under harsh conditions. Extending the life of a furnace depends on how to reduce the wear and tear on the furnace wall bricks around the bottom of the taphole, and operating technology and protecting the furnace wall with mat materials are important issues. The purpose of protecting the furnace wall with mat material is not only to close the tap hole, but also to control the flow of hot metal and slag around the lower part of the furnace wall by increasing the depth of the tap hole.

Ensuring the extension and stability of the taphole depth protects the furnace wall bricks around the taphole at the bottom of the blast furnace, prolonging the life of the furnace, and reducing the amount of residual pig iron and slag during the tapping operation. It is possible to manage operations at a low level of molten metal in the furnace, reduce wind pressure fluctuations, and prevent secondary damage during sudden wind outages due to equipment failure, etc., which greatly improves operational stability and safety. can play a role.

However, although the materials of current mat materials have been improved and advanced, it is not possible to obtain a stable tap hole depth that is sufficiently satisfactory against the movement of the contents in the furnace and the violent flow of hot metal and slag. The current situation is to reduce the inner diameter of the tuyere at the top of the taphole, close the inside of the tuyere, or widen the tuyere spacing.

These countermeasures are undesirable from the standpoint of stable operation because they impair the balance of air volume within the furnace. Therefore, the most important issue is to develop a mat material that is compatible with blast furnace operating technology and to extend the depth of the tap hole.

Therefore, from the viewpoint of the mat material, it is important to improve the corrosion resistance of the mat material, which is the most fundamental factor among the various factors that form the tap hole depth. In recent blast furnace operations, in order to efficiently produce reduced melting of iron ore, a method has been adopted in which lime and MgO-based raw materials are added to self-fusing sinter or pellets by pre-treatment of iron ore, and the ratio of produced slag components (weight %) is 5
i0234%, Fe00.3%, AN20,14%, C
a042%, MgO5-10%, slag basicity (Si
O2/Ca○>#1.2, melting temperature 1250-13
At temperatures as low as 00°C, an increase in alkaline earth metals such as MgO lowers the viscosity of the produced slag and accelerates the rate of erosion of the mat material. In addition, Fe○ is still 0 even in measurements outside the furnace.
．． It is estimated that the content is around 3%, and it is even higher near the tap hole in the furnace.

Therefore, as the MgO content in slag increases, the mat material used changes from chamotte and lowite to high alumina materials, and from 5iO2-SiC-C to SiC2A.
b○x To SiCC system, further Al2O, -8iC-C
silicon nitride or sintering agent (metal silicon or metal aluminum)
The corrosion resistance of matte materials is still insufficient as the operating rate improves.
Developing a mat material with high corrosion resistance is essential for maintaining the stability and depth of the tap hole.

Therefore, the purpose of the present invention is to maintain the tap hole depth, which is particularly important among the characteristics of the mat material, in a long and stable state, thereby stabilizing the operation and tapping work and protecting the blast furnace wall bricks. The object of the present invention is to provide a mat material for a blast furnace taphole that can extend the life of the furnace.

[Means for Solving the Problems] That is, the present invention comprises 5 to 50% by weight of spinel consisting of M, ○・A 120's as main constituents, and the balance being coke, silicon carbide, silicon nitride, alumina, clay, The present invention relates to a spinel mat material for blast furnace tapholes, characterized in that it is composed of a refractory raw material selected from the group consisting of pitch and a sintering agent, and an organic binder.

[Function] The mat material for blast furnace taphole of the present invention contains slag components Cab, Sin, AI! present near the taphole in the furnace. 202, Mg
By using spinel (MgO・AN203) mineral as the main raw material especially for MgO and Fe○ components among O and FeO, conventional A120s-SiC2 quality, A
With I203 raw materials, the formation of low melting point minerals is unavoidable,
It solves the problem of insufficient corrosion resistance and has the best corrosion resistance for the slag.

Conventionally, the main refractory aggregates for mud materials have been chamotte, silicate ore, loite, natural alumina, fused alumina, sintered alumina, etc., but the mat material for blast furnace tapholes of the present invention uses only the main aggregates. Alkaline earth metal oxides (CaO, Mg0) and Fe in the slag components are removed using alumina spinel (Mgo・A (1203)) mineral made by electrofusion or sintering.
It is made difficult to generate low melting point compounds with respect to O.

Furthermore, from the well-known phase diagram, CaOCaO-5i02 system,
Cao S io 2 A bo z series, SinS
in2Al2O3-based, Ca0-AI220*-MgO
system, C12A12s io 7-AN, Os-Mg
Af204 series, Ca2A1zSiOt-CaA&', S
iOs-MgAILO< system, Fe0-MgO system, FeO
-A120. From a system perspective, it is preferable to use spinel (MgO.A1203) mineral as an aggregate in the reaction with each slag-forming mineral.

Spinel (MgO・A 120 s > Minerals are MgO and AN20
The refining ratio of ゜ is Mg010~45% by weight and A120
It is effective in the range of x90 to 55% by weight. If Mg010 is less than 1% by weight in the spinel mineral, even if the blending ratio of the mat material is increased to 50% by weight, there will be no difference from the single alumina raw material and there will be no effect. Furthermore, if M and O exceed 45% by weight, there may be no effect due to the influence of SiO2, A1201, etc. in the slag components, or conversely, melting loss may increase.

The blending ratio of spinel mineral to the mat material is effective in the range of 5 to 50% by weight for spinel raw materials produced by electrofusion method or sintering method, and there is almost no effect in other cases. The blending ratio of spinel minerals is also related to the particle size of the spinel raw material; for example, if the particle size of the spinel raw material is 75μI or less,
A range of weight percentages is valid. With the above particle size, if the blending ratio of the spinel raw material is less than 5% by weight, there is no difference from that of the alumina raw material alone, and if it exceeds 20% by weight, the amount of particles of 75 μm or less in the mat material oval ratio becomes too large. Therefore, the amount of binder added increases in terms of mud gun filling workability, which has a negative effect on the properties of the mat material, and also reduces corrosion resistance. Spinel particle size 31IIM or less is used as other raw material coke,
When combined with spinel (silicon carbide, clay, pitch, silicon nitride, sintering agents, metallic silicon, metallic aluminum, etc.), it is effective up to a spinel blending ratio of 50% by weight, and above that, the mat material properties may be affected due to the composition of other raw materials. It becomes unsatisfactory and inappropriate.

Further, as the organic binder, coal-based binders, petroleum-based binders, resin-based binders, etc. can be appropriately selected and used.

[Example] The mat material for blast furnace taphole of the present invention will be further explained below by giving an example.

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

In addition, according to the mixing ratio shown on each side above, the temperature of the kneaded soil during kneading using a lower mixer 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 both cases. The specimens for measuring the characteristic values in Table 2 were obtained by pressure molding the kneaded clay described above at a molding pressure of 150 kgf/c+a2.

The corrosion resistance comparison in Table 2 is A method: 155 by high frequency induction furnace.
This is a comparative test using 10 kg of pig iron and 300 g of blast furnace slag as corrosive agents at 0° C. for 3 hours, replacing the material 6 times. In addition, method B: 1550°C x 3 hours using a rotating arc furnace, replacing blast furnace slag 1200i + XB times as an erosive agent (furnace rotation number 4 r
pm) This is a comparative test. The corrosion index is a comparative value when Comparative Example 8 is set as an index of 100 using maximum corrosion depth for method A of corrosion resistance comparison test and erosion volume for method B.

The mat material for blast furnace tapholes of the present invention, which uses spinel as a refractory aggregate, has significantly improved corrosion resistance of 1.1 to 1.9 times that of the above-mentioned recent blast furnace slag compared to conventional materials. was completed.

In addition, the mand material for blast furnace taphole of the present invention was used for 4500 m'
When we conducted an actual machine test in a large blast furnace, the tapping time was 1
．． The tap hole depth was extended by 1 to 1.3 times, and the tap hole depth was extended by 100 to 400 mm, making it possible to significantly improve the stable operation of the blast furnace.

[Effects of the invention] The mat material for blast furnace tapholes of the present invention is spinel (MgO'
The main raw material is Al2O3) mineral, and the slag component that is present near the taphole in the furnace, namely CaO1A 1202,
It is possible to prevent a decrease in corrosion resistance caused by the MgO and FeO components in particular among MgO and FeO, thereby providing a mat material for a blast furnace taphole that has excellent corrosion resistance against the above slag.

Claims (1)

[Claims] 5 to 50% by weight of spinel consisting of MgO・Al_2O_3 as the main component, and the balance being coke, silicon carbide,
A spinel blast furnace tap material comprising a refractory raw material selected from the group consisting of silicon nitride, alumina, clay, pitch, and a sintering agent and an organic binder.