Specialized metallurgical processes – compositions for use therei – Compositions – Solid treating composition for liquid metal or charge
Reexamination Certificate
2000-08-02
2001-04-10
Wu, David W. (Department: 1713)
Specialized metallurgical processes, compositions for use therei
Compositions
Solid treating composition for liquid metal or charge
C524S343000, C106S284000, C106S502000, C264S030000
Reexamination Certificate
active
06214081
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a hot repair mix for repairing various types of refinery furnaces, molten metal containers, etc. in hot working process.
BACKGROUND ART
In the past, hot gunning material, hot baking material, etc. have been used as hot repair material for repairing damaged portion of furnace wall, furnace bottom, etc. in various types of refinery furnaces, containers, etc. such as converter, AOD (argon oxygen degassing) furnace, electric furnace, LF ladle, etc. To produce this type of hot baking material, refractory material such as dolomite, magnesia, etc. is kneaded with coal tar binder, and mass of this material having some consistency is supplied and brought into contact with the damaged portion in the furnace through furnace inlet after molten steel has been delivered in case of converter and the baking material is molten, spread and developed by heat inside the furnace and the damaged portion is repaired.
The properties required for this type of baking material are: no change over time, good spreading property in hot working process, good adhesive property, high durability, and short baking and hardening time. The baking material produced by the use of coal tar binder has no problem in such factors as the change over time, spreading property, and durability, while it is disadvantageous in that longer hardening time is required.
In this respect, to overcome the problem of long baking time of the conventional paste type baking material using coal tar binder, a slurry type baking material has been proposed to reduce the baking time. This material has viscous and fluidizing property and uses liquid novolak type phenol resin, and satisfactory effect has been attained (JP-B-5-41594 and JP-B-6-31161). Because solvent is contained in the phenol resin solution, there are less carbon components when it is carbonized. For this reason, it has such problems that it has lower strength when hardened and it is subject to changes over time due to sedimentation and separation of coarse particles during storage because it is a baking material having viscous and fluidizing property.
Also, a powder type baking material has been proposed (JP-A-4-170370) to reduce the baking time and to improve durability. This is produced as follows: A mixed powder type basic refractory material is coated with pitch and/or creosote oil, and to this powder material, aromatic petroleum resin containing heavy oil and C
9
fraction as main components is added as auxiliary combustion agent and wetting agent. By this material, it is possible to reduce the hardening time and it can also provide high strength by carbon bond when it is hardened. However, it has such problems that it is solidified during storage in summer season because of creosote oil or heavy oil, which are added as auxiliary combustion agent and wetting agent.
Further, another type of baking material has been proposed (Japanese Patent Publication No.2555850), which is produced by adding a material to form carbon bond in hot working process and also by adding lactam as auxiliary fluidizing agent. However, it has disadvantages in that lactam has high deliquescence and is changed to polyamide through ring-opening polymerization in the presence of water and alkali metal and it is also solidified during storage in summer season or under high temperature and high humidity conditions.
Still another baking material has been proposed (JP-A-8-169772), which is produced by adding diphenyl or diphenylamine as auxiliary fluidizing agent to a material to form carbon bond in hot working process. However, its adhesive strength is not high enough compared with the conventional products.
It is an object of the present invention to provide a hot repair mix, which is suitable for use to carbon bonded brick such as magnesia-carbon brick used in various types of refinery furnaces and which has sufficient adhesive property with base material and durability suitable as repair material. Further, it forms carbon bond in hot working process, shows neither sedimentation separation nor changes over time, has high spreading property in hot working process, is shorter in the baking time after the processing and has high durability.
DISCLOSURE OF THE INVENTION
A first hot repair mix according to the present invention comprises bisphenol as an auxiliary fluidizing agent in an amount of 1 to 20 weight parts and a material to form carbon bond in hot working process in an amount of 5 to 40 weight parts to 100 weight parts of a refractory material.
A second hot repair mix according to the present invention comprises p-alkylphenol as an auxiliary fluidizing agent in an amount of 1 to 20 weight parts and a material to form carbon bond in hot working process in an amount of 5 to 40 weight parts to 100 weight parts of a refractory material.
The present invention also provides a material as described above, wherein the material to form carbon bond in hot working process is a pitch having softening point of not higher than 300° C.
According to the present invention, bisphenol or p-alkylphenol is added as an auxiliary fluidizing agent to a hot repair mix, which comprises a refractory material and a material to form carbon bond in hot working process. It has good spreading property, hardenability, adhesive property and high physical property in processing result, and it contributes to improvement of durability of the baking material. Moreover, the material of the present invention is not subject to changes over time such as solidification, sedimentation separation, etc. Thus, it can be easily transported and stored. Further, it is easy to handle and apply, and baking repair can be accomplished within short time.
BEST MODE FOR CARRYING OUT THE INVENTION
As the refractory material to be used in the present invention, a material suitable for the base material at the portion to be repaired can be used. For example, basic oxides such as magnesia, dolomite, calcia, etc., neutral oxides such as alumina, chromia, etc., acidic oxides such as silica, zircon, zirconia, etc., non-oxides such as carbon, silicon carbide, silicon nitride, etc. may be used. These may be used alone or in combination. It is preferable that the particle size of the refractory material is similar to that of ordinary type castable refractory material, e.g. it contains fine powder with particle size of not more than 0.3 mm in an amount of 20 to 60 weight %.
As the material to form carbon bond in hot working process, tar, pitch, etc. may be generally used, and phenol resins may be simultaneously used. These may be added in an amount of 5 to 40 weight parts to 100 weight parts of the refractory material, or more preferably in an amount of 10 to 30 weight parts. If it is added in an amount of less than 5 weight parts, sufficient carbon bond cannot be formed, and the finished portion has lower strength and poor adhesive property. If it is added in an amount of more than 40 weight parts, the finished portion has high apparent porosity and is lower in resistance to slag.
The pitch to be used in the present invention may be coal type or petroleum type. Its softening point plays such a role that it is molten by furnace heat and is fluidized. In this respect, the softening point is limited to not higher than 300° C. Normally, it is preferably in the range of 100 to 230° C.
As the phenol resin, it is preferable to use thermoplastic novolak type resin. Preferably, it has melting point of not higher than 120° C. and is in the state of powder or flake at room temperature.
The bisphenol to be used as an auxiliary fluidizing agent in the present invention is a material which is expressed by the following general formula:
HO—C
6
H
4
—CRR′—C
6
H
4
—OH
(where R and R′ each represents hydrogen or alkyl group and may be the same or different). For example, bisphenol A may be used, which is obtained by condensation of acetone and phenol using sulfuric acid or concentrated hydrochloric acid as catalyst and which is expressed by the following formula:
or bisphenol F may be used, which is synthesized fr
Akizuki Toshihiko
Horita Shuzo
Osaki Yoshiaki
Takenaka Hiroshi
Armstrong Westerman Hattori McLeland & Naughton LLP
Egwim Kelechi C.
Shinagawa Refractories Co. Ltd.
Wu David W.
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