KR101157047B1 - Magnesia-chrome redractories and the manufacturing method thereof - Google Patents

Abstract

The present invention relates to a method for producing a magnesia-chromium refractory brick having excellent infiltration resistance to slag used in interior refractory materials such as vacuum degassing equipment, cement kiln, lime kiln, etc., which is magnesium hydroxide (Mg (OH) ₂ ), Seawater magnesia, synthetic magnesia, sintered magnesia, 10-50 wt% of the first mixture obtained by mixing any one or two or more, any one or two of hexametaphosphate, darvan-C, PEI, PEO The second mixture obtained by mixing the above is 0.1 to 1.0wt%, and the remainder consists of impregnating a normal magnesia-chromium refractory brick in an aqueous solution composed of water and vacuum treatment for a predetermined time.

 Magnesia-chrome, firebrick, invasion resistance, interior materials

Description

Magnesia-chrome redractories and the manufacturing method

The present invention is to produce and provide a magnesia-chromium refractory brick having excellent infiltration resistance to slag used as interior refractory materials such as vacuum degassing equipment, cement kiln, lime kiln.

The general magnesia-chrome fireproof brick is composed of magnesia clinker and chromite, and the compounding ratio is 65: 35 ~ 85: 15. According to the viewpoint, the fire brick having increased magnesia to prevent bursting phenomenon of the chrome fireproof brick Alternatively, it can be regarded as a magnesia fireproof brick having improved spalling resistance.

Magnesia-chromium refractory bricks can be classified into chemical bonds, silicate bonds, direct bonds, and recombination fire bricks according to the bonding method of clinkers. The most popular ones are direct bond fire bricks.

The refractory brick of the direct coupling method is a refractory brick fired at 1700 ° C. or more by combining a high purity magnesia clinker and a selected chromite ore, and the magnesia clinker and the magnesia clinker and chromium by a secondary spinel formed during firing. Since iron ore is directly and strongly bonded, the hot strength of the refractory brick is high and the fatigue resistance is excellent.

In Japanese Patent Laid-Open No. 2000-264718, the product is calcined at 1750 ° C. or higher, the Cr ₂ O ₃ content is 16 to 35% by weight, the hot break strength at 1400 ° C. is 3 to ８ MPa, and the hot break strength at 1500 ° C. is 1 to 5 MPa. Magnesia-chromium refractory bricks resistant to molten steel and excellent in spalling resistance have been proposed.

In addition, Japanese Patent Application Laid-Open No. 2000-191364 discloses a method for suppressing the penetration of slag without lowering the thermal shock resistance, assembling a particle diameter of 300 µm or more and less than 5 mm, neutrality of 50 µm or more and less than 300 µm, and 50 µm. It is composed of less than the fine granules, the granulated and neutral fused magnesia chromium particles, the fine particles are used magnesia particles and / or Cr ₂ O ₃ particles, the blending ratio of the granulated, neutral, fine particles are respectively Magnesia-chromium refractory bricks using a raw material having a particle size of 15 to 40% and the particulate magnesia particles and / or Cr ₂ O ₃ particles having a particle diameter of 5% or more and less than 10% by weight in a particle size of less than 1 μm. Presented.

However, a magnesia prepared by the method - if the chrome quality refractory bricks due to secondary spinel is formed during the firing barrel and discipline it is easy to penetrate, such as slag increases, in particular, CaO / SiO _2, low slag basicity ratio is low is the wettability Excellent and penetrates very quickly. At this time, since the properties of the slag infiltrates greatly change, there is a problem in that the peeling by the structural spalling is easy and the service life is reduced.

 The present invention has been made to solve the above problems, and the impregnation and vacuum treatment of a low magnesia-chromic refractory brick in a solution prepared by mixing a fine powder of fine magnesia powder and a dispersant with water for a low basic slag It is to provide a magnesia-chromium refractory brick having excellent infiltration resistance.

Characteristic technical features of the present invention for achieving the above object, the first mixture made by mixing any one or two or more of magnesium hydroxide (Mg (OH) ₂ ), seawater magnesia, synthetic magnesia, sintered magnesia 10 to 50 wt%, 0.1 to 1.0 wt% of a second mixture obtained by mixing any one or two or more of sodium hexametaphosphate, darvan-C, PEI, and PEO, and the remainder of the usual magnesia- It is made by impregnating chromium refractory bricks and vacuuming for a certain time.

And, the vacuum treatment is maintained for 1 to 3 minutes at a vacuum of 0.3 ~ 0.8 atm, the average particle diameter of magnesium hydroxide (Mg (OH) ₂ ), seawater magnesia, synthetic magnesia, sintered magnesia forming the first mixture is 0.5-10 micrometers.

The magnesia-chromium refractory brick of the present invention having the characteristics as described above and a manufacturing method thereof will be described in more detail as follows.

Conventional magnesia-chromium refractory bricks have a large number of open pores due to vigorous secondary spinel reaction during firing. Low basicity slag, which is low in viscosity during operation, is a major cause of the deterioration of life because these pores easily penetrate into the refractory.

Impregnated magnesia powders react with Cr, Fe, etc. evaporated from the inside of the refractory during operation to form secondary spinels near the operating surface of the refractory, where the temperature is relatively high. Play a role in improving the infiltration resistance to slag.

As the magnesia fine powder of the present invention, one or two selected from magnesium hydroxide (Mg (OH) ₂ ), seawater magnesia, synthetic magnesia, and sintered magnesia having a purity of 95% or more was used.

In addition, the average particle diameter of the magnesia fine powder was used in the range of 0.5 ~ 10㎛, the reason is that, if the smaller than 0.5㎛ the manufacturing cost of the aqueous solution is greatly increased, and if it is larger than 10㎛ by reacting with Cr, Fe, etc. This is because the rate of generation of secondary spinels is slow and improvement of corrosion resistance against slag cannot be expected.

In addition, the amount of the magnesia fine powder used is 10 to 50% by weight. For this reason, if the amount is less than 10% by weight, the amount of spinel generated is not expected to improve the infiltration resistance, and when the amount is greater than 50% by weight, the amount of spinel is excessively fine. This is because invasion resistance and corrosion resistance are rather reduced due to cracking.

On the other hand, as a dispersant of the fine magnesia powder, one or two or more components are added from the group consisting of sodium hexametaphosphate, darvan-C, PEI, PEO, and the like, and the amount thereof is 0.1 to 1% by weight, which is why This is because, when less than 0.1% by weight, the dispersibility of the fine powder is low, so that the impregnation effect is low, and when the addition amount is more than 1% by weight, the impregnation effect is equivalent, but the manufacturing cost of the solution is high, which is not preferable.

10-50% by weight of the first mixture obtained by mixing any one or two or more of magnesium hydroxide (Mg (OH) ₂ ), seawater magnesia, synthetic magnesia, and sintered magnesia as described above, and hexametaphosphate 0.1-1.0 wt% of the second mixture obtained by mixing any one or two or more of any one, darvan-C, PEI, and PEO, and the remainder is impregnated with a conventional magnesia-chromium refractory brick in water for a predetermined time. Vacuum treatment in the impregnation tank, the vacuum degree is maintained at 0.3 ~ 0.8 atm. The reason for this is that the lower than 0.3 atm is equivalent to the effect of impregnation, but the manufacturing cost is high. If the higher than 0.8 atm, sufficient impregnation is not achieved.

And, the degree of vacuum is maintained for 1 to 3 minutes, because if the holding time is less than 1 minute, sufficient impregnation is not achieved, so the effect of improving the infiltration resistance is small. If it is longer than 3 minutes, the impregnation effect is equivalent, but the manufacturing cost increases, which is not preferable.

Hereinafter, described through an embodiment of the present invention. The embodiments described below are presented to aid the understanding of the present invention, but the present invention is not limited to the following examples.

[Examples]

Magnesia-chromium refractory bricks were prepared under the mixing and firing conditions presented in Japanese Patent Application Laid-Open No. 2000-191364. 10-50 wt% of one or two or more components from the group consisting of magnesium hydroxide (Mg (OH) 2), seawater magnesia, synthetic magnesia, sintered magnesia, etc. having an average particle diameter of 0.5 to 10 µm, water, and hexa A solution was prepared by mixing one or two or more components by extrapolating 0.1 to 1.0 wt% of a dispersant consisting of sodium metaphosphate, darvan-C, PEI, PEO, and the like.

The refractory solution was prepared by pouring the impregnated solution into a vacuum chamber, putting the prepared refractory brick, and maintaining the vacuum degree at 0.1 to 1 atm for 0.5 to 10 minutes. After the impregnation treatment, the refractory brick was heat-treated at 100 ° C. for 12 hours to remove moisture from the solution. The characteristics of fire bricks which were not impregnated and fire bricks manufactured by different impregnation conditions were evaluated. CaO = 45 wt%, SiO ₂ = 41 wt%, MgO = 5 wt%, MnO = 2 wt%, Al ₂ O ₃ = 4 wt%, P ₂ O ₅ = 0.5 wt%, FeO = 2.5 wt% Synthetic slag was prepared and then subjected to an erosion test at 1620 ° C. using a rotary erosion machine.

In addition, the specimens in the condition of impregnation effect but rising manufacturing cost were excluded from the evaluation. After the test, the specimens were cut and the erosion thickness and the thickness of the infiltrating layer were measured from the cut surfaces. The measured value of the refractory brick without impregnation was set at 100 and converted into an index value. Table 1 shows the impregnation conditions and test results of the refractory bricks used in the test.

Table 1

Impregnation Conditions and Test Results of Specimen

Magnesia particle size (㎛) Magnesia content (wt%) Dispersant content (wt%) Vacuum degree
(atmospheric pressure) Impregnation time (minutes) Corrosion resistance of mine
Invasiveness ratio
School
Yes One Processing 100 100 2 0.05 35 0.5 0.5 2 - - 3 25 5 0.5 0.5 2 100 99 4 2 70 0.5 0.5 2 99 100 5 2 35 0.01 0.5 2 80 85 6 2 35 1.5 0.5 2 99 100 7 2 35 0.5 0.5 2 - - 8 2 35 0.5 0.1 2 100 100 9 2 35 0.5 One 2 - - 10 2 35 0.5 0.5 0.5 99 100 11 2 35 0.5 0.5 10 - - room
city
Yes 12 One 35 0.5 0.5 2 110 120 13 2 40 0.5 0.4 3 115 120 14 2 40 0.5 0.5 2 110 120

As shown in Table 1, in Comparative Examples 1 to 9 prepared under conditions outside the scope of the present invention, it can be seen that low basicity of the infiltration resistance and low corrosion resistance to slag. On the other hand, in Examples 10 to 14 prepared in the range of the conditions of the present invention, very low invasion resistance to slag and corrosion resistance is very excellent.

Magnesia-chromium refractory brick of the present invention as described above is excellent in infiltration resistance to low basic slag, when used in interior materials, such as vacuum degassing equipment, cement kiln, lime kiln, stabilization of operation by greatly improving the service life It is effective in reducing costs.

Claims (4)

As a method of producing a magnesia-chromium refractory brick having excellent infiltration resistance to slag using a magnesia-chromium refractory brick product composed of magnesia clinker and chromite, and having a compounding ratio of 65:35 to 85:15, 10-50 wt% of the first mixture obtained by mixing any one or two or more of magnesium hydroxide (Mg (OH) ₂ ), seawater magnesia, synthetic magnesia, and sintered magnesia, sodium hexametaphosphate, darvan-C, The second mixture obtained by mixing any one or two or more of PEI, PEO and 0.1 ~ 1.0wt% of the remainder, and the remainder was impregnated with the magnesia-chromium refractory brick product in an aqueous solution consisting of water and vacuum treatment for a certain time Magnesia-chromium refractory brick manufacturing method characterized in that. The method of claim 1, wherein the vacuum treatment is a magnesia-chromium refractory brick manufacturing method characterized in that it is maintained for 1 to 3 minutes at a vacuum of 0.3 ~ 0.8 atm. The magnesia-chromium refractory brick according to claim 1, wherein the average particle diameter of magnesium hydroxide (Mg (OH) ₂ ), seawater magnesia, synthetic magnesia, and sintered magnesia constituting the first mixture is 0.5 to 10 µm. Manufacturing method. Magnesia-chromium refractory brick prepared by the method of claim 1.