JPS6360168A - Monolithic refractories - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a basic monolithic refractory.

[Prior art] Conventional #i-based monolithic refractories are disclosed in Japanese Patent Application Laid-open No. 1986-65.
It is known to utilize basic aluminum lactate as seen in 761.

Furthermore, JP-A-58-99177 shows that it is possible to prevent hydration of MgO by using amorphous silica fine powder in an MgO-based amorphous refractory.

Furthermore, in JP-A No. 60-108373, the addition of silica raw materials causes cracking due to heating and cooling.

Known to prevent cracking.

[Problems to be solved by the invention] However, with only MgO clinker and basic aluminum lactate, the fluidity of the clay and the strength development after firing are insufficient, and the strength is low at 800 to 1000°C because lactic acid disappears at high temperatures. In addition, when using conventional SiO2 ultrafine powder, alumina cement is often used in conjunction with it, so when used for MgOQ, there is a limit to the extension of the pot life, and corrosion resistance is not always guaranteed. The results were not satisfactory, as those using siliceous raw materials often use alumina cement as the nubinder, with a large additive amount ranging from 1O to 45vt$.
There was a problem with corrosion resistance.

[Means for solving the problem] The present invention has been made to solve the above-mentioned problem,
In basic refractories using MgO clinker, 1
00, the following particles are 70wH or more, and the following particles are 10wt$ 1! Below is > IgO clinker lO
~50wt$ and basic aluminum lactate 0.1wt$
~5 wt$, (A) particle size of 5 or less, (7) 2 to 8% ultrafine powder, (B) at least selected from silica, silica sand, waxite, and clay with particle size of 1 m/m or less. 2-8 of 1 type
%, a monolithic refractory containing 4 to 10% as a total amount of (A) and (B). Other refractory aggregates used in the present invention include commonly used MgO, Al2O3
,) IgO・Al2O3, chromium steel, ZrO2, S
iC etc. are used as appropriate. In addition, most of these aggregates are generally used as those having a particle size of 5 mm to 100 uL. Further, as the 2M80 clinker, seawater, natural sintered clinker, or electrofused clinker is used.
The particle size of the fine powder part of MgO clinker is 100,
Which of the following particles? More than Owt$ and 1 particle less than sμ
It is preferable for the reason f below that the refractory contains 10 to 50 wt$ of the entire refractory (dry weight basis) of 0 wt$ or less.

That is, if the content of ioo JJ and the following is not 70wtX or more, a gap occurs in the particle size distribution, resulting in an increase in porosity and a decrease in strength. Furthermore, if the content of 5μ or less is more than 10%, slaking is likely to occur during storage, and if the particle size of the MgO clinker fine powder specified here is less than 10% of the entire refractory, the curing time becomes longer, which is a problem in use. Also, 5
If it is more than 0 wt$, the shrinkage after heating becomes large, which is not preferable.

Any known basic aluminum lactate can be used, and Taxeram M-2500 manufactured by Taki Chemical Co., Ltd. is suitable.As for the basic aluminum lactate, the molar ratio of Al2O3/lactic acid is 0.2 to 2.0. Seed level is appropriate. If the amount added is less than 0.1wt$, the amount of water added will increase and the porosity of the construction body will increase, which is undesirable.
If it exceeds %, lactic acid will disappear during heating and the amount of gas generated will increase, making the construction object brittle. Furthermore, aluminum lactate is expensive, and from an economical point of view, it is preferably 0.1 to 5 wt$.

Suitable SiO2 ultrafine powders are those with a particle size of 5 tones or less, such as silica flour or evaporated silica, and the addition amount is preferably 2 to 8%.9 SiO2 ultrafine powders with a particle size of 5 tones or less are less than 2 wt$. If it is present, MgO gas raking occurs during drying and cracks occur. Moreover, if it is more than 8 vt$, the viscosity of the clay will increase and pouring work will become impossible.

If it is less than 5, there will be problems with the fluidity of the clay and the strength of the construction body. Furthermore, the combination of the above-mentioned MgO fine powder, aluminum lactate, and SiO2 ultrafine powder alone has the disadvantage that it is difficult to sinter because MgO has a very high melting point, and the strength after firing is not increased. To solve this, S:
It is possible to further add 02 ultrafine powder, but this is not practical due to the problem of reduced workability as mentioned above.Therefore, it is recommended to add Si02-containing minerals such as silica stone, silica sand, waxite, and clay. It was found that this method is effective in developing strength after firing. The amount of these added is 2~8wt$
If it is less than 2wt$, the strength improvement effect is poor, and if it is more than 8wt$, the effect up to the amount added cannot be obtained,
This is because it also has the disadvantage of reduced corrosion resistance.

In terms of particle size, it is preferable to have a particle size of 1 l/m or less from the viewpoint of uniformly dispersing the particles in the matrix.

In addition, the total amount of S+02kB fine powder and SiO7-containing minerals must be at least 4 wt$, but the upper limit is 12 wt$.
The goal is to keep it at $. This is because if the amount is too large, corrosion resistance will decrease.

Although the refractory of the present invention has the above-mentioned composition, it is effective to use a curing accelerator and/or a curing retardant to adjust the curing time if necessary.
Preferred ways of using them are, for example, as follows.

That is, as a curing accelerator, at least one of carboxylic acid and aluminum sulfate is blended in an amount of 0 to 1 wt$, and as a curing retarder, an alkaline earth metal carbonate or the like is blended in an amount of 0 to 5%.

[Example] Examples are shown in Table 1, and 1, 2.3 are comparative examples.

A further explanation of Table 1 is as follows.

No. 1 uses alumina cement instead of aluminum lactate, which cracks occur after drying at 400°C and has a short pot life, making it impractical.

2 uses ultrafine Al2O3 powder instead of ultrafine SiO2 powder, but cracks occur after drying at 400°C, making it unusable. In addition, 3 uses aluminum lactate and Si02
It is a combination of ultra-fine powders and is good with no cracks after drying at 400°C, but it does not swell hot and does not provide sufficient durability in areas where abrasion resistance is required. Compared to the comparative example, the hot strength is more than double, making it possible to improve the durability. In addition to NgO, chromite, Al2O3, and 9iC are used as aggregates for the No. 7 and later examples.
It also shows that other aggregates can also be used.

The corrosion resistance index is the result of a slag erosion test conducted in a high frequency induction furnace, and the product of the present invention is not significantly different from Comparative Example 3, but compared to Comparative Example 1 using alumina cement.
This shows that the corrosion resistance is very poor.

Table 1 [Effects of A-light] As described above, the present invention provides a basic castable in which aluminum and ultrafine Si powder are added to MgO of a predetermined particle size.
By using O2 together with SiO2-containing minerals such as silica stone, silica sand, waxite, and clay, it is possible to manufacture products that have excellent workability and crank generation, as well as high strength. It is very suitable for ware materials for tundishes, lances, heating furnace hearths, cement rotary kilns, waste liquid incinerators, etc.

Claims (1)

[Claims] 1. In basic amorphous refractories using MgO clinker, particles of 100μ or less are 70wt% or more and 5μ
MgO clinker 1 containing 10 wt% or less of the following particles:
0 to 50 wt%, furthermore basic aluminum lactate 0.1 wt% to 5 wt%, and (A) particle size 5.
2-8% SiO_2 ultrafine powder of less than μ, (B) particle size 1 m
/m or less of SiO_2 such as silica stone, silica sand, waxite, clay, etc.
2 to 8% of at least one mineral contained in (A) and (B)
Monolithic refractories each containing 4 to 12% as a total amount.