JPH0274569A - Indeterminate refractory material - Google Patents

Abstract

PURPOSE:To produce an indeterminate refractory for casting work having excellent durability by compounding a refractory raw material having regulated particle size with an alumina cement and a specific synthetic pulp fiber at specific ratios and adding a proper amount of a water-reducing agent to the mixture. CONSTITUTION:A refractory raw material (e.g., alumina, zircon or chamotte) having regulated particle size is added with (A) 1-8wt.% of alumina cement, (B) 0.1-3wt.% of a hydrophilic and thixotropic synthetic pulp fiber having a length of 0.5-2mm (polyethylene fiber having a melting point of about 130-150 deg.C and a specific gravity of about 0.9-1.0) and (C) a proper amount of a water- reducing agent (e.g., sodium tripolyphosphate). An indeterminate refractory having high strength and excellent burst resistance and thermal spalling resistance can be produced by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a monolithic refractory, and particularly to a monolithic refractory for pouring construction.

(Prior art) Monolithic refractories for pouring construction can yield high-density construction bodies, so they are used in the construction of various molten metal containers.However, during heating and drying after pouring into molten metal containers and construction, The moisture contained in the refractory becomes water vapor, and the vapor pressure inside the refractory increases, which can cause the refractory to peel or explode.Also, repeated heating and cooling during use can cause thermal spalling. Sometimes.

In order to solve these problems, attempts have been made to prevent pulp fibers obtained from waste paper and cotton fibers from being mixed into refractories.

[Problem to be solved by the invention]

However, the pulp fibers mentioned above have strong water absorption and no thixotropy, so the amount of water added is large, and during kneading,
There is a problem that the fluidity of the refractory during pouring construction is inhibited (that is, the workability is poor), and the filling properties and strength of the resulting construction body are reduced. Furthermore, at the site where it is used, it takes a long time to dry and heat up after construction, and it is difficult to manage this. Furthermore, there is also a problem in durability in areas where there is a large temperature difference during use.

This invention was proposed in view of the above-mentioned conventional circumstances, and it does not improve workability during construction, and it does not improve workability during construction. It is a monolithic refractory that has excellent durability in pipes, etc.), has a short drying time, facilitates drying and heat rise management, and has high strength, explosion resistance, and heat spalling resistance. The purpose is to provide shaped refractories.

[Means to solve the problem]

In order to achieve the above object, this invention adds 1 to 8% by weight of alumina cement to a refractory raw material whose particle size is adjusted, and a length of 0.5% by weight.
It is characterized by the addition of 0.1 to 3% by weight of thixotropic and hydrophilic synthetic pulp fibers of ~2 mm, and an appropriate amount of a water reducing agent.

[Effect]

The synthetic pulp fiber used in the present invention has a length of 0. 5-2m
It is a polyethylene fiber made hydrophilic and has thixotropic properties and good dispersibility. In addition, although it is hydrophilic, it has low water absorption, so there is no need to increase the amount of water added, so it is possible to make the construction body highly dense. The synthetic pulp fiber has a melting point of 130 to 150°C and a specific gravity of 0.9 to 1.0. If the length of the synthetic pulp fiber exceeds 2 mm, the thixotropic properties will be impaired, and if the length is less than 0.5 mm, the explosion resistance will be poor. The appropriate amount to use is 0.1 to 3% by weight.
Even if it exceeds 0.1% by weight, no effect of improving explosion resistance or heat spalling resistance is observed, and if it is less than 0.1% by weight, sufficient explosion resistance cannot be obtained.

One or more kinds of alumina cements that are generally commercially available can be used, and the appropriate amount to be added is 1 to 8% by weight.

If the amount used is less than 1% by weight, sufficient strength will not be obtained in the construction body. In addition, since the amount of construction water is small, 8% by weight
Even if the alumina cement is used in excess of this amount, unhydrated alumina cement will remain in the construction body, reducing the strength of the construction body.

Refractory raw materials include alumina, zircon, chamotte,
Mullite, magnesia, silica, etc. can all be used, and the particle size is adjusted as appropriate.

Regarding refractory aggregate, the particle size is adjusted to 50 to 70.
Use % by weight. If less than 50% by weight of refractory aggregate is used, the particle size structure will be rich in fine powder, and therefore the amount of construction water will increase, making it impossible to obtain a densely packed construction body.
If an amount exceeding the weight is used, the particle size structure will be too rich in coarse grains, and a densely packed construction body cannot be expected.

The refractory fine powder used has a particle size of 74 μm or less. Regarding the amount used, it is appropriate to use 30 to 40% by weight, and if it is less or more than that, the workability during construction will be impaired. Furthermore, due to the relationship with the above-mentioned refractory aggregate, the filling properties of the construction body are also adversely affected.

Furthermore, in the present invention, a water reducing agent such as sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate is used in order to reduce the amount of water added during pouring construction and obtain a high-density construction body. Furthermore, a regulator can be used to adjust (accelerate or delay) the curing time during construction, if necessary.

〔Example〕

Table 1 shows the Example product of the present application, the conventional product ■■, and the comparative product ■■■■ whose synthetic pulp fibers are outside the scope of the present invention, and also shows the characteristics of each.

As is clear from Table 1, the monolithic refractory for pouring construction according to the present invention has less drop in hot strength (maintains high strength) than conventional products or other comparative products, and has excellent explosion resistance and heat spalling resistance. It is excellent and does not impair workability during construction.

Further, when the above-mentioned example was poured and used for the pigtail receiving port of a pig iron mixer car at Steel Works A, no problems occurred in terms of workability or durability.

〔Effect of the invention〕

As explained above, this invention adds thixotropic and hydrophilic synthetic pulp fibers, so it does not impair workability during construction and has excellent durability in areas with large temperature differences during use. We were able to obtain a monolithic refractory for pouring construction that shortened the drying time and facilitated drying and heat rise management.

Claims (1)

[Scope of Claims] [1] One part of alumina cement is added to the particle size-adjusted refractory raw material.
~8% by weight, 0.1 to 3% by weight of thixotropic and hydrophilic synthetic pulp fibers with a length of 0.5 to 2 mm;
A monolithic refractory characterized by further adding an appropriate amount of a water reducing agent.