JPH08259311A - Production of magnesia-carbonaceous refractory brick - Google Patents

Abstract

PURPOSE: To provide a method for producing a magnesia-carbonaceous refractory brick capable of manifesting characteristics comparable to those of a conventional brick in reutilizing the used magnesia-carbonaceous brick as a brick aggregate in order to reduce the brick cost effectively utilizing a brick waste. CONSTITUTION: A magnesia clinker and carbon are added to 5-50 pts.wt. pulverized brick waste material obtained by pulverizing a magnesia-carbonaceous refractory brick used in a kiln to have the maximum particle diameter or below of an aggregate constituting the brick to make up the total amount to 100 pts.wt. An additive containing an antioxidant is further added to be mixed and regulate the mixture so that the total composition may be 69-89wt.% magnesia, 10-30wt.% carbon and 1-5wt.% additive containing the antioxidant. A binder is then added thereto to carry out the forming and drying of the resultant mixture. A brick waste prepared by removing particles having <1mm particle diameter in the brick waste obtained by pulverizing the refractory brick is especially preferably used and the pulverized brick waste material is preferably used after heat-treating thereof at 100-600 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a magnesia-carbonaceous refractory brick lined in a furnace for molten steel.

[0002]

2. Description of the Related Art Magnesia-carbon refractory bricks
Magnesia clinker with a particle size of about 5 mm or less, such as natural magnesia obtained by calcining magnesite ore, seawater magnesia extracted from seawater, and fused magnesia obtained by melting natural magnesia to increase purity, and a particle size of scaly graphite of about 300μ
It is manufactured by molding a powder using a resin, which is obtained by using carbon of m or less as a raw material and further adding a metal having a particle size of several tens of μm or less such as Al or Mg as an antioxidant.

Since magnesia-carbonaceous bricks are used in a very harsh environment such as a converter, a high-grade raw material has hitherto been aimed at. Electro-fused products are often used as magnesia clinker, and high quality scaly graphite is used as carbon.

However, due to the progress of operation and repair techniques, the load on bricks is reduced under harsh environments, and the high durability of magnesia-carbonaceous bricks is no longer in high demand, but rather the cost of bricks is reduced. It has become important.

[0005]

By the way, since the magnesia-carbonaceous brick does not easily infiltrate the slag, even if it is a used brick, the inside of the brick retains almost the same quality as the brick before use from the operation side. ing. Especially the quality of magnesia does not deteriorate. Although the carbon is slightly oxidized and consumed, it is only oxidized and reduced in size, and the characteristics of the scaly graphite are not deteriorated. However, these used bricks were conventionally discarded. Due to environmental issues, effective use of these wastes is desired.

The present invention regenerates used magnesia-carbonaceous bricks into newly used bricks,
The purpose is to reduce the cost of bricks by effectively utilizing the waste materials of bricks and manufacturing bricks that can exhibit the same characteristics as conventional bricks.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, in the present invention, the magnesia-carbonaceous refractory brick used in a kiln is made to have a particle size not larger than the maximum particle size of the aggregate constituting the brick. Magnesia clinker and carbon were added to 5 to 50 parts by weight of brick waste pulverized material obtained by pulverization to make a total of 100 parts by weight, and an additive containing an antioxidant was further added to give an overall composition of magnesia 69 to 89. The present invention is characterized in that after mixing and adjusting so as to be 1 to 5% by weight of an additive containing carbon, 10 to 30% by weight of carbon, and an antioxidant, a binder is added, followed by molding and drying.

Alternatively, as a brick crushing material, a magnesia-carbonaceous refractory brick used in a kiln is crushed to a particle size not larger than the maximum particle size of the aggregate constituting the brick, of which particles having a particle size of less than 1 mm. It is more preferable to use a crushed material of brick scraps obtained by removing. In this case as well,
Magnesia clinker and carbon were added to 5 to 50 parts by weight of brick crushed material to make a total of 100 parts by weight, and an additive containing an antioxidant was further added to make the total composition 69 to 89% by weight of magnesia and carbon 10 to 10 parts by weight. After 30% by weight and 1 to 5% by weight of an additive containing an antioxidant are mixed and adjusted, a binder is added and the mixture is molded and dried.
In particular, as the crushed brick waste material, it is preferable to use one that has been subjected to heat treatment at 100 to 600 ° C. after crushing or after removing particles having a particle diameter of less than 1 mm.

[0009]

The function of used magnesia-carbonaceous refractory bricks is high in porosity due to the oxidation of carbon, and if they are used as coarse grains, the properties are deteriorated because they have internal pores. Therefore, in the present invention, a used magnesia-carbonaceous refractory brick is crushed to a particle size equal to or smaller than the maximum particle size of the aggregate constituting the brick. The maximum particle size of aggregate generally used for bricks is about 5 mm. By crushing used magnesia-carbonaceous refractory bricks to 5 mm or less, magnesia-like particles and magnesia-carbonaceous particles can be obtained.

The magnesia particles have the same characteristics as the conventional magnesia clinker. Magnesia-carbonaceous particles are particles based on bricks obtained by high-pressure molding of scaly graphite and magnesia aggregate, which are difficult to fill due to their shape, to increase the filling property, and therefore already have sufficient compactness. Have. Further, since the particles obtained by pulverization have larger surface irregularities than the raw material particles, they have good wettability with the liquid binder and are effective in homogenizing the strength.

In the present invention, the crushed brick waste material 5 as described above is used.
To 50 parts by weight of magnesia clinker and carbon to a total of 100 parts by weight, and an additive containing an antioxidant is added to make the total composition of magnesia 69 to 89.
Wt%, carbon 10 to 30 wt%, and additives containing an antioxidant 1 to 5 wt% after mixing and adjusting,
A magnesia-carbonaceous refractory brick is obtained by adding a binder, molding and drying.

Brick crushed material, magnesia clinker,
And the content of crushed brick waste in carbon is 5 to 5
When the content is 0% by weight and the content is less than 5% by weight, the characteristics which are not different from the conventional ones can be obtained. However, effective brick cost reduction and waste material reuse cannot be achieved. On the other hand, as the content increases, the characteristics gradually deteriorate,
It has been found that the upper limit of the content is 50% by weight in order to maintain at least the durability as conventional.

By the way, as described above, the used magnesia-carbonaceous refractory brick has different components from that of the unused brick due to partial oxidation of carbon and the antioxidant, or is particularly crushed by crushing. Since the components used in the fine powder portion are reduced, it is necessary to adjust the components in order to maintain the durability equivalent to the conventional one.

Therefore, in the present invention, the magnesia clinker, carbon, and antioxidant are so adjusted that the total composition is 69 to 89% by weight of magnesia, 10 to 30% by weight of carbon, and 1 to 5% by weight of an additive containing an antioxidant. The compounding amount of the additive including the agent is adjusted. Thereby, the entire composition of the magnesia-carbonaceous refractory brick of the present invention is made the same as that of the conventional brick.

As the magnesia clinker, electrofused magnesia or sintered magnesia, etc. are used, as the carbon, scaly graphite or the like, and as the antioxidant, Al—Mg metal or the like is used. After adjusting the composition of the whole component in this way, a binder is added in the same manner as in the prior art, followed by molding and drying to produce a magnesia-carbonaceous refractory brick.

Further, in the present invention, as a brick crushing material to be used, a magnesia-carbonaceous refractory brick which has been used in a kiln is crushed to a particle size equal to or smaller than the maximum particle diameter of the aggregate constituting the brick, and the particles are crushed. It is even better to use a crushed brick waste material obtained by removing particles having a diameter of less than 1 mm. The inventors found out that the waste material of the magnesia-carbonaceous refractory brick was crushed and the components thereof were analyzed, and in the case of the waste material mixed with slag and the like, the slag was likely to collect in the fine particle portion.

The fine particles in the crushed material of brick scraps deteriorate the characteristics of the brick and must be removed. It has been empirically found that when various waste materials are pulverized to have a particle size of 5 mm or less, components such as slag are contained in fine particles having a particle size of less than 1 mm. Therefore, in the present invention, it is recommended to use a pulverized material from which particles having a particle diameter of less than 1 mm are removed.

Further, in the present invention, after crushing the crushed brick waste material or after removing particles having a particle size of less than 1 mm, 100 to
It is recommended to heat it at 600 ° C. before use. As described above, the magnesia-carbonaceous refractory brick is added with a metal such as Al or Si as an antioxidant. It is conceivable that some of these will remain unoxidized even after the brick is used, and that it will be digested by cooling water when the brick is dismantled and by moisture absorption during crushing and storage. Therefore, if it is used as it is, the newly manufactured brick deteriorates. Therefore, in order to sufficiently oxidize and stabilize the remaining antioxidant, the crushed brick waste material is preliminarily heat-treated at 100 to 600 ° C. before use.

In order to remove the water adhering to the crushed brick waste material, it is necessary to heat at least 100 ° C. or higher. On the other hand, 600 ° C. is the upper limit for suppressing the oxidation of carbon contained in the crushed brick waste material. The above temperature range is sufficient to oxidize the antioxidant contained in the used brick, but the temperature is preferably 400 ° C or higher, and therefore, the preferable temperature range is 400 to 600 ° C.

[0020]

EXAMPLES Examples and comparative examples of magnesia-carbonaceous refractory bricks produced according to the present invention are shown in Table 1 together with their characteristics. The used brick scraps are magnesia-carbon refractory bricks that have been used in the converter and have a maximum particle size of 5
It was manufactured using mm magnesia aggregate.
Then, after removing the slag adhering to the above-mentioned brick waste, it was crushed to a particle size of 5 mm or less by a jaw crusher and classified into 5 to 3 mm, 3 to 1 mm, and less than 1 mm. In addition, as a comparative example, 10
A crushed brick waste of ~ 5 mm was also obtained.

Analysis of the components in each particle size range of the brick waste revealed that the particle size was 5 to 3 m with respect to the brick component when it was not used.
m, 3 to 1 mm, magnesia is about 10% more and carbon is about 5% less, and less than 1 mm magnesia is about 10%.
% Was less and carbon was about 10% more. On the other hand, the particle size of 10 to 5 mm was almost the same as that of the unused component.

As shown in Table 1, in each of the five cases except Comparative Example 6, the raw materials were replaced by the bricks of Comparative Example 7 (unused bricks).
Al2Mg was added so that the particle size composition and the scaly graphite content would be the same.
A metal was added in an amount of 2% by weight, and a brick was prepared and evaluated.

The slag erosion index is C / S = 1.1, T.S.
Using the synthetic slag of Fe = 3% by weight, the erosion depth when the rotary erosion test was performed at 1700 ° C. for 8 hours was shown as a relative value when the erosion depth of brick 7 was 100. The smaller the value, the better the slag melting resistance.

The heat resistant spall is 40 × 40 × 230 mm
Using a brick, a cycle of dipping in hot metal at 1600 ° C. for 90 seconds and then cooling with water for 30 seconds was repeated 15 times, and the number of times when the brick came off was shown. The larger the value, the better the heat-resistant spalling property.

Further, the apparent porosity and the bending strength were tested at room temperature after the brick was prepared and further baked in a reducing atmosphere at 1400 ° C. for 3 hours. The bending strength index is shown as a relative value when the bending strength of Brick 7 is 100, and the larger the value, the better.

The bricks of Examples 1 and 2 show approximately the same characteristics as the brick of Comparative Example 7 when the amount of brick waste added is 30 to 40% by weight, and there is no problem in an actual furnace. I was able to use it. The brick of Example 3 was a brick obtained by removing crushed brick scraps having a particle size of less than 1 mm, and was particularly excellent in slag melt damage resistance.

On the other hand, the bricks of Comparative Examples 4 and 5 are bricks containing 60% and 80% by weight of brick waste, respectively, and have high apparent porosity, slag melting resistance, heat resistant spall resistance, and bending strength. It was In addition, the brick of Example 6 has a particle size of 10 to 5 m, which is equal to or larger than the maximum aggregate particle size of the used brick.
This is a brick to which m bricks were added, and the filling property was poor, and the slag melt resistance and bending strength were poor.

[0028]

[Table 1]

Also, although not shown in Table 1, the bricks produced with the same grain size constitution as the bricks of Example 1 after firing the brick scraps at 500 ° C. have the same physical properties as those of Example 1 immediately after the brick production. Almost unchanged. Further, even when the bricks were stored for a long time after production, the physical properties were hardly deteriorated as compared with the bricks of Example 1.

[0030]

According to the present invention, it is possible to effectively use the scraps of the brick containing the high-grade raw material, which was conventionally a waste, and the cost of the brick can be reduced.

Claims (3)

[Claims] 1. A crushed brick waste material, obtained by crushing a magnesia-carbonaceous refractory brick used in a kiln furnace to a maximum particle size of aggregate constituting the brick or less, in an amount of 5 to 50 parts by weight, Total 1 including magnesia clinker and carbon
In addition, the total composition of magnesia 69 to 89% by weight, carbon 10 to 30% by weight, and the additive 1 to
A method for producing a magnesia-carbonaceous refractory brick, which comprises mixing and adjusting so as to be 5% by weight, adding a binder, molding and drying. 2. A magnesia-carbonaceous refractory brick used in a kiln is crushed to a particle size not larger than the maximum particle size of the aggregate constituting the brick, and particles having a particle size of less than 1 mm are removed. Magnesia clinker and carbon were added to 5 to 50 parts by weight of crushed brick waste to make a total of 100 parts by weight, and an additive containing an antioxidant was further added to make the total composition 69 to 89% by weight of magnesia and 10 parts by weight of carbon. ~ 3
A method for producing a magnesia-carbonaceous refractory brick, which comprises mixing and adjusting the content of 0% by weight and an additive containing an antioxidant to 1 to 5% by weight, adding a binder, and molding and drying. 3. The magnesia according to claim 1, wherein the crushed brick waste material is used after crushing or after removing particles having a particle size of less than 1 mm and then heat-treating at 100 to 600 ° C. Carbon refractory brick manufacturing method.