Coating processes – Spraying – Ingredients supplied separately
Patent
1988-10-12
1991-01-01
Beck, Shrive
Coating processes
Spraying
Ingredients supplied separately
427427, 264 30, B05D 110
Patent
active
049817310
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INDUSTRIAL USE
The present invention relates to a method for gunning a refractory composition to produce a lining body having high density and high strength.
PRIOR ART
Conventionally methods for gunning a monolithic refractory have been used in places where lining is difficult by casting or stamping. Gunning methods have such merits as no lining mold is needed, thereby enabling cost reduction, high working efficiency and easy hot lining and are therefore widely used. Gunning methods can roughly be divided into dry types and wet types. As they require a lot of water for lining compared with high density castable materials or stamping materials which use super fine powder and a dispersion agent as disclosed in Japanese Patent Publication No. 51-9770, Japanese Patent Application Laid Open No. 51-109008 and Japanese Patent Application Laid Open No. 52-58723, a refractory lining body obtained by gunning has high porosity, low density and deteriorated strength.
As a method for decreasing water for lining in a method for gunning, a dry type gunning method in which lining is carried out using a gunning material containing a surface active agent is disclosed in Japanese Patent Application Laid Open No. 58-24785. However, even this method requires move than 10% water for lining, and for this reason a sharp improvement in quality has not yet been achieved.
PROBLEMS TO BE SOLVED
Although the methods for applying said super fine powder and a dispersion agent of a high density castable material disclosed in the above described Japanese Patent Publication No. 51-9770, Japanese Patent Application Laid Open No. 51-109008 and Japanese Patent Application Laid Open No. 52-58723, were considered for application to a gunning method, in a dry type gunning method, as in the method for using said surface active agent, the time for mixing, and kneading the water for the lining and a gunning material at the gunning nozzle is very short so that a sufficient reduction in water can not be obtained and sharp improvements in quality of the lining body can not be expected.
On the other hand, when a gunning material containing super fine powder and a dispersion agent is used for lining by a wet type gunning method, since the gunning material is kneaded with the total amount of lining water, a sufficient effect of the dispersant can be obtained. However, when the total amount of water for lining is about the same as that of the high density casting material, the viscosity of the kneaded gunning material is high and the pressure pumping through a hose for the material is difficult. For this reason, it is necessary to increase the water for lining over that of the high dense casting material, so only a small improvement in quality of the lined body by gunning can be expected.
MEANS FOR SOLVING THE PROBLEMS
The object of the present invention is to resolve the above described problems, reduce the lining water in the method for gunning and obtain a lined body by gunning having high density and high strength.
Accordingly, the present invention presents a method for gunning a refractory composition composed of 93-60 wt. % refractory aggregate, 5-30 wt. % refractory super fine powder, 1-20 wt. % alumina cement and 0.01-0.5 wt. % (outer percentage) dispersion agent together with 0.01-2 wt. % (outer percentage) of a hardening accelerator characterized in that said refractory composition is previously mixed with water amounting to 1/5-3/4 of the total amount of water for the gunning, is then conveyed under pressure by dry gunning equipment, a solution containing the remaining amount of water and the hardening accelerator being subsequently added to said mixed refractory composition at a gunning nozzle of said dry gunning equipment.
OPERATION
The refractory aggregates used in the present invention are such as calcined refractory clay, bauxite, sillimanite, mullite, alumina, silicon carbide, zircon, magnesia, chromite etc.. The preferable amount of addition for the refractory aggregates is 93-60 wt. %, amounts exceeding 93 wt. % n
REFERENCES:
patent: 4461789 (1984-07-01), Takashima
patent: 4535001 (1985-08-01), Greener
patent: 4751204 (1988-06-01), Kyoden et al.
English (partial) translation of Japanese Kakai Patent Sho 54(1979)-95615.
Hattori Ichiro
Kubota Yukitoshi
Yamamura Takashi
Yorita Eiichi
Beck Shrive
Shinagawa Refractories Co. Ltd.
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