JPH0637333B2 - Refractory composition for hot repair - Google Patents

Description

The present invention relates to a refractory composition for hot repair used as a repair material for various kilns such as a converter, an electric furnace, an AOD furnace, and a ladle.

[Conventional technology]

Injecting repair material from the furnace opening as a hot repair material for converter walls, electric furnaces, AOD furnaces, ladle and other furnace walls and furnace bottom, and filling the damaged part by baking this repair material with furnace heat etc. Baking material for hot repair is used.

This baking material is made of magnesia, dolomite and other basic aggregates with coal tar pitch added as a binder in plastic form, solid form, powder form with granular pitch, thermoplastic resin and thermosetting resin. Alternatively, there is a plastic type used in combination.

[Problems to be Solved by the Invention]

However, coal tar pitch produces smoke and gas during baking, and contains toxic substances in the volatile gas, which is not preferable in the working environment. Further, since it takes a long time to be carbonized and solidified, the operation efficiency is lowered, and if the operation is started in a state where the seizure is insufficient, the durability is lowered and it is difficult to obtain a sufficient repair effect.

As described above, the baking material using coal tar pitch as a binder emits a lot of smoke during repair and requires a long time to cure. Further, the baking material using the thermoplastic resin has a rather slow curing time, and the baking material using the thermosetting resin does not flow at all because the thermosetting is too early. In particular, it is important to shorten the repairing time as well as the refining time of recent converters, and there has been a strong demand for a hot repairing baking material having a short baking time.

[Means for Solving the Problems]

The present invention, as a result of studies for solving these problems, a composition containing a thermoplastic resin and dinitronaphthalene as a binder in a refractory aggregate has a short baking time, a small amount of smoke, and an excellent hot fluidity, The present invention has been achieved by finding that it has excellent durability.

That is, the present invention is characterized by using dinitronaphthalene as a curing accelerator in a refractory aggregate and a thermoplastic resin.

Examples of the refractory aggregate used in the present invention include basic aggregates such as magnesia and dolomite, and acidic or neutral aggregates such as silica, zircon and alumina. Further, if necessary, a carbonaceous substance such as graphite, pitch powder, carbon black or the like may be added to improve the corrosion resistance.

As the thermoplastic resin, novolac type phenol resin,
Polyvinyl chloride, polyethylene, polystyrene, polypropylene, polyvinyl acetate, polybutene resin, etc. may be used, but novolac type phenol resin is preferable, and the addition amount of these binders is 10 to 30% by weight.
I like to be. If it is less than 10% by weight, there is a problem in hot fluidity, and if it exceeds 30% by weight, the effect is not particularly improved and the cost becomes high, which is not preferable.

Dinitronaphthalene as a curing accelerator is powdery and solid at room temperature and liquefied at a relatively low temperature by heating,
It has the effect of accelerating the curing of the thermoplastic resin without impeding the fluidity during heat. The amount of dinitronaphthalene added is preferably 0.5 to 5% by weight with respect to the mixture of the refractory aggregate and the thermoplastic resin. If it is less than 0.5% by weight, the curing acceleration effect is small, and 5% by weight. If the amount exceeds 5%, the effect of increasing the amount is not significant, so addition of more than 5% by weight is meaningless.
The particle size of dinitronaphthalene is not particularly limited, but it is preferably 2 mm or less.

〔Example〕

 The following table shows the compounding compositions and test results of the product of the present invention and the comparative example.

The hot fluidity was measured by dropping 1 kg of the sample on a castable plate heated to 1000 ° C. and measuring the diameter spread by the flow of the sample. The flow stop time was measured as the time until the sample flow stopped and the sample did not spread to the surroundings. The smoke emission was visually observed. Curing time is 500g sample in steel can,
The sample was placed in a furnace heated to 600 ° C., and the time until the surface of the sample was cured was measured.

All the products of the present invention show excellent fluidity in a short time, and the curing time is shortened to about 1/3 as compared with the material using the coal tar pitch-based binder.

The material using the coal tar pitch-based binder has good fluidity, but it takes a long time to cure and emits much smoke.

[Effects of the Invention] The hot repairing refractory composition of the present invention, by adding dinitronaphthalene, promotes the shortening of the curing time without inhibiting the hot fluidity, so that the baking time is longer than that of conventional products. It has been greatly shortened and has excellent durability.

Claims (1)

[Claims] 1. A refractory composition for hot repair, characterized in that a thermoplastic resin and dinitronaphthalene are blended with a refractory aggregate.