JPH0631177B2 - Construction method of cast molding refractory and blast furnace cast floor gutter. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to various metal melting furnaces, heating furnaces, firing furnaces, etc., and molten metal melters including cast bed gutters, ladles, tundishes, etc. of blast furnaces. Propellers and injection pipes for agitation used for lining and for molten metal treatment such as desulfurization.
The present invention relates to an improvement in explosion resistance of a cast refractory used for nozzles and the like during heating and drying.

(Problems of the conventional technology) For lining molten metal containers such as various metal melting furnaces, heating furnaces, firing furnaces, blast furnace casting floor gutters, ladles, tundish, etc., and stirring for molten metal processing Propellers, injection pipes, cast molding refractories used for nozzles, etc. are mainly alumina or high alumina raw materials, in which silicon carbide, graphite, etc. are blended depending on the application, in addition to alumina cement as a binder, If necessary, clay and / or powdery pitch, resin, or the like may be added. Further, a fluidity-imparting agent may be added in some cases.
In use, a mixture obtained by hydro-kneading these compositions is poured into a space of a predetermined frame to fill and mold a predetermined structure. Next, this molded product is subjected to natural curing, or if it needs to be deframed for a short period of time, it is cured by heating and cured, then deframed, and dried by heating for use. About 4 to 20 external weight% of water is added to the powder composition.
Most of the water content is used for imparting fluidity during the above-mentioned casting, and remains in a free water state in the structure of the molded body after curing. And a part is consumed for reacting the component (CaO.Al ₂ O ₃ ) of the alumina cement in the casting material composition to generate a hydrate. The hydrated product fills the voids of the molded body and becomes a colloidal amorphous or crystalline compound that exhibits a binding force between the products or between the product and the aggregate particles. This hydrate is transformed into a metastable hydrate by heating. Therefore, the main purpose of heating and drying before entering the use state is to remove free water, which accounts for most of the added water, rather than changing the state of the hydrate.

In general, when the molded body is heated and dried, the surface layer of the molded body may explode and fly off when the molded body is blown (explosion). Occasionally, an explosion may occur in which the molded body is destroyed from the inside and scattered as a large lump. This explosion occurs when the vapor pressure due to free water generated in the compact by heating exceeds the strength of the compact base material, but the mechanism of the cause is complicated, so it is appropriate. In many cases, preventive measures cannot be taken. On the other hand, in the case of a gutter material for a blast furnace casting floor, an organic binder such as a powder pitch or a powder resin may be added to the composition in order to improve the corrosion resistance and heat resistance of the casting material. These pitches and resins are usually in a softened and molten state from less than 100 ° C to a hundred and several tens of ° C in the structure of the molded body due to heat received during heating and drying. It will seal the open pores created after the water splashes. Therefore, it prevents the subsequent free water splashing,
The molded body has a significantly increased vapor pressure inside and is more susceptible to explosion than in the case of the alumina cement single binder. This explosion is dangerous and hinders the planned operation of various furnaces and sometimes causes personal injury.

In order to solve the above problems, a method of adding metallic aluminum powder to a casting material is generally used as a measure for preventing explosion, and a method of adding sodium perborate powder has been experimentally conducted. However, if aluminum aluminum powder is added to the casting material using water as a kneading liquid,
As a result of the reaction of aluminum with the kneading liquid, hydrogen gas is generated together with heat generation. Due to the decrease of the water content due to the heat generation and the increase of the air permeability due to the generation of gas, the molded body has a structure that is easily dehydrated at the time of heating and drying to prevent explosion. However, the problem is that the hydrogen gas generated at that time has a risk of causing hydrogen gas explosion due to fire.

In the case of aluminum perborate powder, oxygen gas is generated as a reaction between the casting material and water. However, even if there is no possibility of causing a dangerous phenomenon such as hydrogen explosion when the powder of metallic aluminum is added, oxygen gas promotes combustion, so that it has a drawback in that it is not sufficient in terms of safety.

(Means for Solving Problems) The present invention has been made to eliminate the explosive phenomenon at the time of heating and drying of the cast refractory material described above, and the first invention is to eliminate incombustible gas by decomposition. A cast molding refractory characterized in that an appropriate amount of the generated organic foaming agent is blended, and a second invention is the cast molding refractory of the first invention in which a foaming aid is blended with the above organic foaming agent. A casting refractory characterized by being mixed in an amount of approximately 1/5 to approximately the same amount, the third and fourth inventions respectively show examples of an organic foaming agent and a foaming auxiliary agent, and 5th and 6th inventions are related to the construction method of the blast furnace cast floor gutter using the casting refractory material of the 3rd and 4th invention, respectively.

That is, by adding a proper amount of an organic foaming agent powder that generates a harmless, odorless and inert gas by decomposition, that is, a pollution-free gas to a cast molding refractory made of a binder such as a refractory material and alumina cement. It was intended.

(Working) Refractory materials are mainly alumina materials such as fused alumina and sintered alumina, high alumina materials such as sillimanite, mullite and bauxite, basic materials such as chamotte, silica, magnesia and spinel, and carbonized materials. One or more selected from silicon, graphite, etc. are used. As the binder, in addition to alumina cement, clay and / or powdered pitch, resin, or the like is blended, if necessary. Further, a fluidizing agent such as a peptizer may be added in some cases.

The selection conditions were nontoxic, odorless, nonflammable, and so-called pollution-free as a component of the generated gas that forms deaeration holes during heating and drying. As a result, as the organic foaming agent satisfying this purpose, 4,4′-oxybisbenzenesulfonyl hydrazide, P-toluenesulfonyl hydrazide, acetone-P-toluenesulfonyl hydrazide, P-toluenesulfonyl semicarbazide, hydradicarboxylic acid isobrovir and diphenyl sulphate were used. It was effective to use one or more of bon-3,3'-disulfonylhydrazide, trihydrazinotriazine and 5-phenyltetrazole. Since these organic foaming agents are thermally decomposed by receiving heat from the low temperature in the initial stage of heating and drying, and mainly generate nitrogen gas, there is no danger and there is no pollution.

The casting refractory to which an appropriate amount of these organic foaming agents have been added is cast as a water-mixture, cured, cured, deframed, and then heat dried. In the case of casting at room temperature, the drying takes a long time at an ambient temperature of about 100 ° C. and is started at a very low temperature. Therefore, before the reduction of free water scattering inside the molded body becomes active, that is, before the steam pressure inside the molded body rises, the organic foaming agent decomposes and evolves gas sufficiently in the initial stage of heating and drying. Vents are formed in the structure of the molded body by the gas generated from the foaming agent. The presence of the ventilation holes, in other words, the degassing holes, can significantly reduce the risk of explosion. On the other hand, in the case of repairing, there is a case where the back lining brick and the remaining old material have residual heat at the time of casting, and the casting is performed in a warm or hot atmosphere. In this case, the organic foaming agent presents decomposed gas during curing before deflaming, and degassing holes are formed in the structure of the molded body. Therefore, before the start of heating and drying, the molded body has a good dryability and a structure with excellent explosion resistance, which is advantageous.

Next, the ratio of the organic foaming agent used will be described. Although it varies depending on the type of the compounded organic foaming agent, if the content of the organic foaming agent is approximately 0.05% or less by weight, the effect of the addition is not so significant.
On the other hand, when the content is 2.0% or more, the amount of generated gas becomes excessive as compared with the formation of gas deaeration holes, the inside of the molded body becomes porous, and lamination (layer crack) is formed, so that the homogeneity of the molded body structure becomes uniform. Tends to be lost.

The present invention, as described above, has the advantage of being pollution-free when constructing a pouring material, and exhibits an excellent effect as a countermeasure against explosion, but there are various circumstances in the construction site in reality, and there is an adjustment range during heating and drying. There is a case that the heating temperature fluctuates beyond the limit, the planned temperature adjustment cannot be performed depending on the construction site, and occasionally the heating and drying is rapidly completed depending on the operation situation, and there is no choice but to use it early. If you don't have one, you may encounter it. Therefore, as a result of further research, the inventors of the present invention added the above-mentioned constitutions of the first and third inventions to a foaming aid equal to or more than ⅕ or less of the organic foaming agent to obtain the above-mentioned invention. It promotes gas foaming at a lower temperature and at an earlier timing, heating the pouring material during such drying with explosion and heating, and high flexibility even if there are fluctuations in severe temperature conditions, making it safer I found that I could handle it. With this foaming aid, the gas generation start temperature can be shifted from the low temperature range and the gas generation start time can be shifted to an early stage. An example of this effect is shown in FIG. That is, the second or fourth invention is the above-mentioned first and third inventions.
The casting refractory containing the organic foaming agent obtained in the invention of (1) above is further blended with a foaming aid in an amount equal to or more than ⅕ of the organic foaming agent. Examples of the foaming aid include hydrated and kneaded refractory compositions that are alkaline, such as sodium or potassium silicates, carbonates, or a combination thereof. In this case, if the blending amount is ⅕ or less, the above effect is not sufficient, and if the amount is more than the equivalent amount, the effect reaches a ceiling and the sodium and potassium components unfavorable for the refractory material increase. The foaming aid is preferably a finely powdered inorganic salt consisting of a weak acid and a strong base, considering that the cast molding refractory is a mixed powdered product and the storage stability at the time of inventory, for example, sodium and potassium. Silicates, carbonates, etc. can be easily applied. In the alkaline aqueous solution, the above-mentioned organic foaming agent group originally has a property that the decomposition temperature is lowered to near room temperature, and as a foaming auxiliary agent to be added so that the hydro-kneaded poured refractory material becomes alkaline, these The substance is easy to handle and is effective for the purpose of addition.

Examples of the present invention will be shown below.

Example 1 (Table 1) For a typical high alumina bone material alumina cement bond cast molding refractory composition consisting of 50 parts by weight of calcined bauxite, 35 parts by weight of synthetic mullite, and 15 parts by weight of alumina cement. 4 from the group of organic foaming agents
Select 4'oxybisbenzenesulfonyl hydrazide, add 0.5 parts by weight of this and mix with water to obtain 100φ
A cylindrical specimen having a size of 100 mm × 100 mm was prepared. After the sample was cured in a sealed state at room temperature for 24 hours, the explosiveness test of the cured test sample was performed. In the explosiveness test, the test piece was instantaneously inserted from the outside of the furnace heated to 600 ° C. in the ceiling direction to almost the center of the furnace, and the state change due to rapid heating of the test piece was observed. In this case, when the explosion caused a change in the state, such as a chipped tip or a ruptured body, a quantitative comparison was made of the weights of these exfoliations. As a comparative example, a comparative example 1 and an additive-free additive without any measures against explosion were provided.
The test results show that when an alumina cement bond cast material (Comparative Example 1) having no organic foaming agent added, that is, a conventional composition having a very general composition, is exposed to severe rapid heating conditions, an explosion of 30% by weight occurs. As compared with the case of peeling off due to the result of Example 1, Example 1 showed good results with no peeling off due to explosion. In addition, the physical properties obtained by adding the organic foaming agent are also shown in Comparative Example 1
There is not much change.

[Example 2] (Table 1) Pyrroline was used as a deflocculating agent for reducing the amount of sintered alumina (75 parts by weight), silicon carbide (20 parts by weight), alumina cement (5 parts by weight) and kneading added water to improve the compactness of the construction body. Example 2 was added with 0.7 part by weight of P-toluenesulfonyl hydrazide to a low-alumina cement bond cast molding refractory composition consisting of 0.05 part by weight of acid soda. An explosiveness test was conducted in the same manner as in Example 1, and comparative investigations were conducted. The result is the addition of no organic blowing agent,
That is, even in Comparative Example 2 which is a general low-alumina cement bond cast molding refractory, peeling due to explosion of 20 wt% was caused by rapid heating, whereas in Example 2, sound and good. It showed a good result. Further, the physical properties of Example 2 are almost the same as or higher than those of Comparative Example 2.

[Example 3] (Table 1) Pyrroline was used as a deflocculant to reduce the amount of sintered alumina 92 parts by weight, magnesia 5 parts by weight, alumina cement 3 parts by weight, and the amount of water added for kneading, and improve the compactness of the construction body. 0.3 parts by weight of 4,4 ′ oxybisbenzenesulfonyl hydrazide and P-toluenesulfonyl hydrazide as an organic foaming agent were added to a low-alumina cement bond cast molding refractory composition consisting of 0.05 parts by weight of acid soda. The composition added with 0.3 part by weight is referred to as Example 3 and Example 1
A comparative study was conducted in the same manner as. In this case, Comparative Example 3 in which no organic foaming agent was added had 50% by weight of flaking off, whereas Example 3 showed good results with no flaking due to explosion. This indicates that the combined use of two kinds of organic foaming agents is effective for improving the drying property. Thus, the physical properties of Example 3 are not much different from those of Comparative Example 3.

[Example 4] (Table 2) 72 parts by weight of fused alumina, 20 parts by weight of silicon carbide, 5 parts by weight of powder pitch, 1.5 parts by weight of kibushi clay, and 1.5 parts by weight of alumina cement. Addition of 0.05 parts by weight of sodium pyrophosphate for the purpose of reducing the amount of water to be added and improving the compactness of the construction product to the compounding of the organic foaming agent with 4,4 ′ oxybisbenzenesulfonyl hydrazide. Was added, and 0.5 parts by weight of this was added as Example 4, and the mixture was mixed with water to obtain 100φ mm × 100H.
A cylindrical specimen of mm was made. 60 ° C with the sample sealed
After the curing for 3 hours, the explosiveness test of the cured specimen was conducted. In the explosiveness test, the specimen was instantaneously inserted from the outside in the ceiling direction of the furnace heated and maintained at 600 ° C. to almost the center of the furnace, and the state change due to rapid heating of the specimen was observed. As a comparative example, a comparative example 4 is one in which no additive is added and no additive is added, and a metallic aluminum powder added by a conventional method (0.2%) is comparative example 5. As a result of the test, Comparative Example 4 in which no additive was added exhibited an explosion in a disjointed state in which the original shape of the specimen was not retained. That is, 100
%, Whereas Example 4 showed no peeling due to explosion and showed the same good results as Comparative Example 5 in which the metallic aluminum powder was added. Comparative Example 5 is a typical mixture example used as a cast refractory for a blast furnace cast floor gutter, but is a carbon-based powder organic binder for the purpose of improving properties such as corrosion resistance and thermal shock resistance. Powder pitch is blended here. As described above in the section [Problems of the prior art], this powder pitch is likely to be in a state where the molded body is more likely to explode during heating and drying. In the case of Comparative Example 4 in which the test was not performed, the test piece was in a disjointed state (delamination amount 100%) after the test and could not retain its original shape.

Next, the one shown in this example was used as an actual furnace for the blast furnace tappipe. In a state in which the old residual material surface temperature was 80 ° C., 25 tons of pouring was carried out to a large gutter in front of the tap hole of a 3000 m ³ class large-scale blast furnace, and it was put to practical use. After the same overnight curing as the casting material for troughs with the addition of metallic aluminum powder, which had a conventional explosion resistance against hydrogen gas generation mechanism, it was deframed, heated and dried for 2 days, and then started to lead. In this actual furnace test, no troubles such as explosion, cracks, and peeling occurred from the time of drying to the end of running, and the durability of the gutter was equal to or higher than that of the conventional product.

[Example 5] (Table 2) To the composition used in Example 4, 0.2 parts by weight of potassium carbonate was further added as a foaming auxiliary agent to prepare a sample in the same manner as in Example 4, and from Example 4, Sealed and cured at room temperature (25 ° C.) at low temperature for 24 hours under severe conditions. The explosiveness test was performed in the same manner as in Example 4, and Comparative Example 4 and Comparative Example 5
As a result, in Comparative Example 4 in which no additive was added, explosion was exhibited in a disassembled state in which the original shape of the specimen was not retained. That is, the amount of exfoliation was 100%, while Example 5 had no exfoliation due to explosion, and showed good results as in Comparative Example 5 in which metallic aluminum powder was added.

The one shown in this example was used as an actual furnace for the blast furnace tap pipe. 40
00m ³ class large blast furnace taphole in front of gutter, old residual material surface temperature 3
At 0 ° C., 30 tons of pouring was carried out for practical use. In both cases, after curing overnight for the same as the conventional casting material for gutters with metal aluminum powder added, which had a hydrogen gas generation mechanism to cope with the explosion blast resistance, it was deframed, heated and dried for 2 days, and then passed through the steel. Started. In this actual furnace test, no troubles such as explosion, cracks, and peeling occurred from the time of drying to the end of running, and the durability of the gutter was equal to or higher than that of the conventional product.

(Effect of the Invention) Improvement of Safety Although the cast molding refractory has excellent workability, it has a drawback of causing explosion depending on use conditions. To prevent the explosion, measures such as gentle heating and heating are taken, but forming innumerable degassing holes in the molded body is also a powerful preventive measure. Although it has been practiced to use metallic aluminum powder for forming the degassing holes, there is a drawback that the generated gas has a risk of causing hydrogen gas explosion as described above.

INDUSTRIAL APPLICABILITY Since the present invention is a casting refractory in which degassing holes are formed by using non-hazardous nitrogen gas, it has a great effect that it can be used safely.

Also, comparing the above examples and comparative examples, it is clear that the use of an appropriate amount of the organic foaming agent can prevent explosion without significantly changing the strength.

Shortening of construction period Since the cast molding refractory of the present invention is excellent in drying property, the heating and drying period is shortened and the construction period including drying is shortened.

Energy saving effect Since the drying time can be shortened, the fuel cost can be saved and the energy saving effect is great.

Responsiveness to changes in furnace arrangement Even if the so-called furnace arrangement such as the operation plan of the furnace is changed and the usage is accelerated, heating and drying can be handled with considerable flexibility.

As described above, the present invention has an extremely high industrial utility value from the viewpoints of safety, construction period, energy saving, furnace operation plan and the like.

[Brief description of drawings]

FIG. 1 is a table showing the effect of a foaming aid on an organic foaming agent.

Front Page Continuation (72) Inventor Takeo Hanai 5-3 Tokai-cho, Tokai City, Aichi Prefecture Nippon Steel Co., Ltd. Inside the Nagoya Works (72) Inventor Kazuhiko Takahashi 2-2-3, Fujiyamadai, Kasugai City, Aichi Prefecture ( 72) Inventor Noriyuki Inoue 4-3-3 Misato Toyota City, Aichi Prefecture (72) Inventor Hideaki Ohashi 1-2-24 Eicho Town, Toyota City, Aichi Prefecture (72) Inventor Shinji Motoike 5 Aoki Town, Toyota City, Aichi Prefecture ―20―48 (56) References Japanese Patent Publication Sho 49-31016 (JP, B2)

Claims (6)

[Claims] 1. One or two of fused alumina, sintered alumina, sillimanite, mullite, bauxite, chamotte, silica, magnesia, spinel, silicon carbide and graphite.
It is characterized by adding 0.05 to 2.0% by weight of an organic foaming agent which generates a nonflammable gas by decomposition to a refractory material composition containing a refractory material selected from at least one kind and alumina cement. Refractory for casting. 2. One or two of fused alumina, sintered alumina, sillimanite, mullite, bauxite, chamotte, silica, magnesia, spinel, silicon carbide and graphite.
0.05 to 2.0% by weight of an organic foaming agent that generates a non-combustible gas by decomposition, and a foaming agent of the above organic foaming agent in a refractory material composition in which a refractory material selected from at least one kind and alumina cement is mixed. A foaming aid that promotes
A cast refractory material containing 2.0% by weight of external coating. 3. An organic foaming agent which generates a nonflammable gas by decomposition is 4.4 oxybisbenzenesulfonyl hydrazide, P-toluenesulfonyl hydrazide, acetone-P.
-Toluenesulfonyl hydrazide, P-toluenesulfonyl semicarbazide, hydradicarboxylic acid isobrovir, diphenylsulfone-3,3'-disulfonylhydrazide, trihydrazinotriazine and 5-phenyltetrazole, and one or more kinds thereof. The cast refractory material according to claim 1 or 2, wherein 4. A foaming aid for promoting foaming of the organic foaming agent is one or more of sodium silicate, sodium carbonate, potassium silicate and potassium carbonate. Claims 1 and 2 characterized in that
Alternatively, the cast refractory material according to the item 3. 5. One or two of fused alumina, sintered alumina, sillimanite, mullite, bauxite, chamotte, silica, magnesia, spinel, silicon carbide and graphite.
Fireproofing for casting by adding 0.05 to 2.0% by weight of an external blowing agent to a refractory material composition containing a refractory material selected from at least one species and alumina cement and generating an incombustible gas by decomposition. 4-20% external weight of the product
The method of constructing a blast furnace cast floor gutter characterized by adding the above water, pouring it into a mold, removing the frame, and heating and drying. 6. One or two of fused alumina, sintered alumina, sillimanite, mullite, bauxite, chamotte, silica, magnesia, spinel, silicon carbide and graphite.
An organic foaming agent that generates a non-combustible gas by decomposition in a refractory material composition in which, in addition to the fire-resistant material selected from at least one type and alumina cement, if necessary, clay and / or powdery bitches or resins are mixed. Of 0.05 to 2.0% by weight and 0.01 to 2.0% by weight of a foaming aid for promoting the foaming of the above organic foaming agent, and a peptizing agent as required. A method for constructing a blast furnace cast floor gutter, characterized in that 4 to 20% by weight of external weight% of water is added to a product, poured into a mold, deframed, and heated and dried.