JP2010001186A - Carbon-containing brick for refining furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve service lives of a tuyere brick which is for blowing gas from the bottom of a furnace and a surrounding brick cluster surrounding the tuyere brick in a refining furnace such as a converter and a smelting reduction furnace. <P>SOLUTION: The carbon-containing bricks for a refining furnace are arranged at the bottom of the refining furnace, which are composed of a carbon-containing tuyere brick (1) having a gas passage aperture of gas for the refining furnace and a carbon-containing tuyere-surrounding brick cluster (10) which surrounds the tuyere brick. When carbon contents of the tuyere brick (1) and the tuyere-surrounding brick cluster (10) are expressed as Ct and Cb, respectively, Ct is 100 mass%>Ct>0 mass% and Cb is 100 mass%>Cb>0 mass%, and ΔL obtained by the following formula (1): ΔL=-225.921+15.951Ct+0.905Cb-0.304Ct<SP>2</SP>+0.189Cb<SP>2</SP>(1), is above 60 and not more than 160, while the combination of Cb and Ct satisfies Ct<Cb. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention optimizes the combination of tuyere bricks in which gas is blown from the bottom of the furnace into molten metal such as converters and smelting reduction furnaces, and the surrounding bricks surrounding them, thereby improving the spalling resistance of tuyere bricks. The present invention relates to a new improvement for improvement.

Conventionally, in a refining converter or the like, a tuyere brick having a gas inlet for refining at the bottom is used. Since low-temperature gas is blown from the tuyere, a large temperature difference tends to occur between the tuyere brick and / or the group of bricks around the tuyere. In addition, since back attack of gas occurs, tuyere bricks are easily damaged. In relation to this problem, Patent Documents 1 to 9 described below are disclosed.
That is, Patent Document 1 includes bricks due to magnesia carbon or magnesia dolomite / carbonaceous non-fired brick containing magnesia or magnesia dolomite as an aggregate containing 7 to 35% by weight of carbon in the tuyere brick. An oxygen blowing smelting vessel for steel making is disclosed. According to the publication, it is stated that the durability of brick piles around the blow tuyere is enhanced.

  Patent Document 2 discloses a refractory for top blown converters containing 5 to 100% by weight of scaly graphite and 95 to 0% by weight of other commonly used refractory raw materials and using an organic binder. According to the publication, it is stated that when applied as a refractory suitable for the tuyere and the lining around the tuyere, the spalling resistance is improved, and the durability more than ever is obtained.

  Patent Document 3 discloses a pitch-modified phenol resin-bonded unfired MgO-C brick having a total carbon content of 5% by weight to 10% by weight and the balance of MgO clinker, and a part or all of the furnace wall and / or the furnace bottom. A high-temperature converter characterized by being lined is disclosed. According to this publication, heat spalling properties are secured while suppressing the reaction between MgO and C at high temperatures, chemical erosion by Cr-containing molten steel and prevention of carbon pickup into the molten steel, It describes that deformation can be prevented.

  Patent Document 4 discloses a magnesia whose magnesia carbon brick including electrofused magnesia and a magnesia source are sintered magnesia in a work brick tension structure in a furnace bottom in a converter having a gas injection tuyere at the furnace bottom. It consists of a two-layer stretched region made of carbon bricks, and the single-layer stretch region is continuously formed from at least one location on the outer peripheral end of the furnace bottom to at least one location on the other end, and the two-layer stretched region is a plurality of regions A brick-clad structure at the bottom of the converter is disclosed. According to the publication, it is described that the wear of bricks around the tuyere can be suppressed and the useful life of the furnace bottom bricks can be greatly extended.

  Patent Document 5 discloses a refractory for a stainless steel converter hearth comprising a long magnesia carbon brick containing 3 to 10% by weight of graphite. According to the publication, it is possible to construct a hearth thick without a horizontal joint by a long product, so it is possible to avoid damage acceleration near the joint and to improve the durability of the hearth. Has been.

  Patent Document 6 discloses a refining tuyere composed of a tuyere nozzle for blowing a refining gas and tuyere bricks surrounding the tuyere nozzle, wherein the tuyere nozzle is a graphite pipe, a metal pipe inserted therein, and the graphite. A refining tuyere comprising a long fiber reinforced heat insulating layer provided on the outer surface side of a pipe is disclosed. According to the publication, it is described that there is no abnormal melting of the tuyere, cooling of the surrounding bricks is suppressed, and the wear rate of the tuyere can be reduced, which can contribute to extending the life of the furnace body of the refining furnace.

  In Patent Document 7, magnesia / carbon brick made of a refractory material mainly composed of magnesia is used for all or part of the furnace bottom, with 15 to 40% by weight of expanded graphite having a particle size of 0.3 mm or less. A converter furnace bottom lining is disclosed. According to the publication, it is described that the spalling resistance can be greatly improved while maintaining the corrosion resistance.

  Patent Document 8 defines a combination of the carbon content of a tuyere brick and a tuyen brick group, and by satisfying a certain combination, the width of a gap generated between the tuyere brick and the tuyere brick group. Can reduce spalling damage due to differences in bullion.

  Patent Document 9 discloses that the thermal conductivity of tuyere sleeve bricks is equal to or higher than that of tuyere reinforcement lining bricks, that is, the carbon content of tuyere sleeve bricks is reduced within tuyere reinforcement. By increasing the amount of tension, the joint damage around the tuyere hardware is reduced, and there is no cracking due to thermal spalling, and damage to the whole tuyere can be reduced.

JP 54-54904 A JP-A-57-5811 Japanese Patent Laid-Open No. 01-162714 JP 05-70819 A Japanese Patent Application Laid-Open No. 07-82004 JP-A-10-280027 JP 11-209169 A JP 2003-261374 A Japanese Utility Model Publication No. 57-154751

  Despite the conventional technologies as described above, the durability of the refining tuyere brick has not been improved. Therefore, the present inventors have carefully studied and analyzed the damage situation of tuyere bricks in an actual furnace. As a result, the damage caused by heat spalling is particularly large, and the heat spalling causes several tens to 100 mm from the operating surface at a time. Damage was found in the area.

  Here, the configuration of the above-mentioned Patent Document 8 has found that a bullion pen in which molten iron penetrates during operation between the tuyere brick and the surrounding brick, and this is related to the spalling damage of the tuyere brick. Although it is a patent, as a result of detailed examination, the present inventors have found that spall damage of tuyere bricks occurs even if molten iron does not enter. That is, in the configuration of Patent Document 8, the gap between the tuyere bricks and the tuyere bricks is eliminated, but in the actual machine, the tuyere bricks constrain the tuyere bricks conversely, The large force causes a large stress on the tuyere brick, and the tuyere brick originally also has a great stress due to thermal shock, and these overlaps spur damage to the tuyere brick. I found out. Furthermore, it has also been found that there is a region in which the combination of the amount of carbon in the tuyere brick and the tuyere bricks does not cause a bullion even if the configuration of Patent Document 8 is not disclosed.

The carbon-containing brick for a smelting furnace according to the present invention is a group of carbon-containing tuyere bricks provided at the bottom of the smelting furnace and having gas passage holes for the gas for the smelting furnace, and a group of carbon-containing tuyere bricks surrounding the tuyere brick. 100% by mass>Ct> 0% by mass and 100% by mass>Cb> when the carbon content of the tuyere brick and the tuyere brick is represented by Ct and Cb, respectively. 0% by mass, and ΔL obtained from the following formula (1) is more than 60 and less than or equal to 160, and at the same time, a combination of Cb and Ct satisfying Ct <Cb, and the carbon content Ct and Cb is 14.9 mass% <Ct <22.5 mass% and 22.5 mass% <Cb <27.5 mass%.
ΔL = −225.921 + 15.951 Ct + 0.905 Cb−0.304 Ct ² +0.189 Cb ² (1)

Since the carbon-containing brick for a smelting furnace according to the present invention is configured as described above, the following effects can be obtained.
In other words, there is an optimal combination of the amount of carbon that can be applied to tuyere bricks and the amount of carbon that can be applied to groups of tuyere bricks, and the combination is obtained quantitatively. The gap between bricks can be set moderately, the binding force to the tuyere bricks by the bricks around the tuyere is controlled, and furthermore, no spalling damage due to the metal bar in the gaps occurs, and the tuyere bricks The service life of has been greatly improved. In addition, the service life of tuyere bricks has been greatly improved, so it has been possible to reduce the frequency of repairs and to reduce the frequency of tuyere replacement, which has contributed to the improvement in the utilization rate of refining.

  The present invention improves the spalling resistance of tuyere bricks by optimizing the combination of tuyere bricks in which gas is blown into the molten metal such as converters and smelting reduction furnaces from the bottom of the furnace and surrounding bricks. An object of the present invention is to provide a carbon-containing brick for a smelting furnace.

Hereinafter, preferred embodiments of a carbon-containing brick for a refining furnace according to the present invention will be described with reference to the drawings.
First, the tuyere brick used in the present invention is distinguished from the tuyere brick group 10. As shown in FIGS. 1 to 6, this tuyere brick 1 has a gas passage hole 4 inside and is an integral brick. On the other hand, the tuyere brick group 10 is an aggregate of bricks surrounding the tuyere brick 1, and the tuyere brick 1 and the tuyere brick 10 are bricks that can be physically distinguished from each other. There are joints between this tuyere brick 1 and the tuyere brick group 10, and the joints may be empty joints, or mortar joints made of various materials such as magnesia, alumina, and magcro, and other ordinary joints. The joint allows the tuyere brick and the tuyere brick to be joined.

  The present invention aims to define the combination of carbon content of 1 tuyere brick and 10 tuyere bricks in order to suppress damage due to spalling of tuyere brick 1 and improve durability. Yes. At that time, the group around the tuyere finds the optimal combination of the carbon amounts that can weaken the force that the group 10 restrains the tuyere 1 and the intrusion of the bullion is also intruded by the set carbon amount. The goal is to find the optimal combination of carbon amounts that can be suppressed.

FIG. 1 is a cross-sectional view of a single tube type tuyere brick 1 as viewed from the working surface side. This cross-sectional shape continues substantially from the working surface to the back surface. Therefore, the feature can be shown by the cross section. In addition, although the external shape of the cross section is a square in the figure, this may be a rectangle or a circle.
FIG. 1 shows a single tube type tuyere brick. The heat insulating layer 2 in the figure is provided to suppress rapid cooling of the brick portion due to gas, but this layer may or may not be present. Further, the gas passage hole 4 may be hollow or may be filled with a refractory material having a high air permeability.

  FIG. 2 shows a multi-tube type tuyere brick. A plurality of gas blowing pipes 3 constitutes a concentric circle. Here, an example of a triple pipe is shown.

  FIG. 3 shows a multi-tube type tuyere brick. Here, nine gas blowing pipes 3 are shown aligned, but the number and arrangement can be arbitrarily selected.

  FIG. 4 is a diagram for explaining this patent, showing a combination of the carbon amount of 1 tuyere brick and group 10 of tuyere surroundings, and the range in which the combination of carbon amount can be set from this patent is a one-dot chain line region in the figure A region A, which is surrounded by a dotted line in the figure, indicates a region that is particularly effective in this patent.

  FIG. 5 shows a furnace bottom constructed by a “parallel stacking method” in which bricks are arranged in parallel. One brick is represented by a minimum area surrounded by a line in the figure. As an example, the center of the furnace bottom is arranged in parallel in the horizontal direction, and the upper and lower portions of the figure are arranged in parallel in the vertical direction. In addition, four tuyere bricks 1 are installed. These vertical and horizontal positional relationships may be reversed, and the installation position and number of tuyere bricks can be arbitrarily selected.

  FIG. 6 shows the bottom of a furnace in which bricks are constructed by a method of round winding. In the figure, there is one tuyere brick 1 in the center, and the installation position of the tuyere brick 1 can be arbitrarily selected other than the central part. For example, they can be arranged on a straight line passing through the center of the circle.

  FIG. 7 shows the bottom of the brick built by the method of Ajiro loading. In the figure, two tuyere bricks 1 are installed, but can be installed at any position. The above three types of furnace building methods can also be used in combination with each other. For example, bricks can be arranged at the center of the furnace bottom by the “parallel stacking method” and the outer periphery can be wound by the “round winding method”.

  The tuyere brick 1 and the tuyere surrounding brick group 10 exemplify a plurality of brick structures applied to the carbon-containing brick for a refining furnace according to the present invention. Any combination of bricks 10 is applicable in the present invention.

  Next, examples of tuyere brick 1 and tuyere brick group 10 according to the present invention are shown in Tables 1 and 2 in Tables 1 and 2. Table 1 is an example of the present invention, and Table 2 is a comparison. In Tables 1 and 2, the tuyere life is determined by dividing the tuyere damage amount (damage length) by the number of times of use (number of charges) (mm / ch), and the comparison product 1 in Table 2 It is a value obtained by indexing the degree of each tuyere life when. A larger index number indicates better performance. For example, if the index is 2, it indicates that the durability is twice that of the comparative product 22. From the table, it can be seen that the tuyere brick 1 according to the present invention is more than twice as durable as the comparative product.

Therefore, as is clear from the above-described embodiments, a carbon-containing tuyere brick provided at the bottom of the smelting furnace and having a gas passage hole for the smelting furnace gas and a carbon-containing tuyere brick surrounding the tuyere brick In the carbon-containing brick for a smelting furnace comprising a group, when the carbon content of the tuyere brick and the tuyere brick is expressed as Ct and Cb, respectively, 100% by mass>Ct> 0% by mass and 100% by mass> Cb Carbon content for a smelting furnace that is a combination of Cb and Ct satisfying Ct <Cb, where ΔL shown in FIG. The brick was found to be optimal.
ΔL = −225.921 + 15.951 Ct + 0.905 Cb−0.304 Ct ² +0.189 Cb ² (1)
Further, it has been found that carbon-containing bricks for a smelting furnace satisfying 14.9% by mass <Ct <22.5% by mass and 22.5% by mass <Cb <27.5% by mass are suitable.

It is sectional drawing which shows the single pipe type tuyere brick to which the carbon containing brick for refining furnaces by this invention is applied. It is sectional drawing which shows the multi-tube type tuyere brick which is the other form of FIG. It is sectional drawing which shows the multi-tube type tuyere brick which is the other form of FIG. It is a characteristic figure which shows each carbon amount of a tuyere brick and a tuyere surrounding brick group in this invention. It is a top view which shows the furnace bottom by a tuyere brick and a tuyere surrounding brick group in this invention. It is a top view which shows the other form of FIG. It is a top view which shows the other form of FIG.

Explanation of symbols

1 tuyere brick 2 heat insulation layer 3 gas blow pipe 4 gas passage hole 10 tuyere bricks

Claims (2)

A carbon-containing tuyere brick (1) provided at the bottom of the smelting furnace and having a gas passage hole for a gas for a smelting furnace and a group of carbon-containing tuyere bricks (10) surrounding the tuyere brick (1) In the carbon-containing brick for a refining furnace, when the carbon content of the tuyere brick (1) and the tuyere surrounding brick group (10) is expressed as Ct and Cb, respectively, 100% by mass>Ct> 0% by mass and 100% by mass %>Cb> 0% by mass, ΔL calculated from the following formula (1) is more than 60 and less than or equal to 160, and at the same time, a refining furnace comprising a combination of Cb and Ct satisfying Ct <Cb Carbon-containing brick for use.
ΔL = −225.921 + 15.951 Ct + 0.905 Cb−0.304 Ct ² +0.189 Cb ² (1)   The carbon content (Ct) of the tuyere brick (1) and the carbon content (Cb) of the tuyere brick group (10) are 14.9% by mass <Ct <22.5% by mass and 22.5%. The carbon-containing brick for a refining furnace according to claim 1, wherein mass% <Cb <27.5 mass%.

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