JP3005840B2 - Spinel unfired refractories - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-fired spinel refractory such as a checker brick used in a heat storage room of a glass kiln.

[0002]

2. Description of the Related Art Heretofore, as this kind of unsintered spinel type refractory, there has been known a refractory raw material containing a spinel clinker, a magnesia clinker and the like and a condensed alkali phosphate as a binder. (Special Publication 61-
No. 28622).

[0003]

However, in conventional spinel-based unfired refractories, the condensed alkali phosphates exhibit a strength as a binder of 150 to 200 ° C.
, And the strength is lowered, for example, in a temperature range (about 1000 ° C. or higher) at or above the middle stage of the glass kiln heat storage room. Therefore, an object of the present invention is to provide a spinel-based unfired refractory which can be dried at a low temperature and exhibits excellent strength characteristics in a temperature range from room temperature to a high temperature.

[0004]

In order to solve the above-mentioned problems, a spinel-based unfired refractory of the present invention comprises 100 parts by weight of a refractory raw material mainly composed of alumina-magnesia-based spinel, and 0.5 to 0.5% of sodium aluminate. And 10 parts by weight.

[0005]

In the above means, sodium aluminate functions as a binder, develops strength at a temperature from room temperature to about 100 ° C., and has a high strength stable up to a high temperature (1200 ° C.). A typical composition formula for sodium aluminate is Na
AlO ₂ or Na ₃ AlO ₃ , and the Na ₂ O
The / Al ₂ O ₃ molar ratio is from 1.2 / 1 to 2.6 / 1. If the amount of sodium aluminate is less than 0.5 part by weight, sufficient strength as a refractory cannot be obtained, and
When the amount exceeds the weight part, oversintering occurs during use, and the thermal spalling property is inferior. The chemical composition of the unfired refractory composed of a refractory raw material containing spinel as a main component and others is preferably A
l ₂ O ₃ 10 to 75% by weight, MgO90~25 wt%. This is limited by volume stability caused by the coefficient of thermal expansion, heat-resistant spalling property and alkali corrosion resistance, reactivity with SO ₃ gas in glass furnace exhaust gas, and the like.

[0006]

Embodiments of the present invention will be described below in detail. Examples 1 to 6 Spinel clinker 1 having the chemical composition shown in Table 1
2. Alumina clinker and magnesia clinker were blended in the ratios shown in Table 2, and sodium aluminate (Na ₂ O / Al ₂ O ₃ molar ratio 1.2 / 1) was used as a binder in a known manner. After kneading and molding, the mixture was dried at a temperature of 100 ° C. for 10 hours to obtain a spinel unfired refractory. About these, apparent porosity, bulk specific gravity, bending strength (R.
T-1200 ° C.). Further, a sample fired at a temperature of 1200 ° C. for 10 hours (having a shape of 114 × 230 × 65 m
m) was investigated for heat-resistant spalling property. The above measurement results and investigation results are as shown in Table 2.

Comparative Examples 1-4 Spinel clinker 2 having the chemical composition shown in Table 1
As shown in Table 3, sodium aluminate (N
a ₂ O / Al ₂ O ₃ molar ratio 1.2 / 1;
2) Using sodium tetrapolyphosphate (Comparative Example 3) and sodium hexametaphosphate (Comparative Example 4), kneading and molding by a known method.
At a temperature of 170 ° C. for 10 hours to obtain a spinel-based unfired refractory. With respect to these, apparent porosity, bulk specific gravity, and bending strength (RT to 1200 ° C.) were measured. Further, 1200 ° C
(A shape of 114 × 230 ×
(65 mm). Table 3 shows the measurement results and the inspection results.

[0008]

[Table 1]

[0009]

[Table 2]

[0010]

[Table 3]

[0011]

As described above, according to the spinel-based unfired refractory of the present invention, sodium aluminate functions as a binder and develops strength at a temperature of about room temperature to about 100 ° C. Drying can be performed at a relatively low temperature, and the cost can be reduced. Further, since it exhibits excellent strength characteristics in a temperature range from room temperature to 1200 ° C., it can be used more stably in a higher temperature range than before.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-23004 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/66

Claims (1)

(57) [Claims] 1. 100 parts by weight of a refractory raw material mainly composed of alumina-magnesia spinel, 0.5% sodium aluminate
A non-fired spinel refractory, comprising 10 to 10 parts by weight.