JPH07237977A - Composition for alumina spinel-based cast refractory - Google Patents

Abstract

PURPOSE:To obtain the composition which is a composition, containing an alumina-based aggregate, a spinel and an alumina cement, capable of filling a narrow space without any vibration and having the thermal volume stability for a long period by blending a magnesia aggregate with specific alumina particles and the alumina cement in a specific proportion. CONSTITUTION:This refractory composition is obtained by using a burnt alumina clinker, etc., as an alumina-based aggregate and a burnt spinel clinker (blended in an amount of 3-20%), etc., as a spinel and blending the resultant composition with 1-18wt.% magnesial aggregate, 2-15wt.% alumina particles having <=5mum particle diameter, 8-15wt.% alumina cement having >=73wt.% Al2O3 content and >=5500cm<2>/g Blaine value and further powder of CaO or Ca(OH)2 in an amount of 0.02-0.15wt.% expressed in terms of CaO. Furthermore, the flow value of body prepared by mixing the obtained composition with water in an amount of 6wt.% expressed in terms of outer percentage is >=185mm when the body is cast into a cement flow cone defined by the specification of JIS R-5201 and the flow cone is then taken out to allow the body to stand for 30sec without vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alumina spinel casting refractory which is excellent in fluidity for facilitating its construction and is thermally stable in volume, particularly suitable for ladle.

[0002]

2. Description of the Related Art When compared to a regular refractory, a cast refractory, which is a type of irregular refractory, can significantly reduce the labor required for its construction, and therefore the use of a cast refractory is increasing. Further, as a refractory for lining a large ladle used for smelting using a basic slag, an alumina spinel cast-in refractory having good corrosion resistance to the basic slag is preferably used. In addition, in order to construct the pouring refractory into the ladle, the vibrator attached to the core should be used so that the poured refractory will be completely filled in the space to be constructed. A construction method is adopted in which vibration is applied to the refractory that is poured by the vibrator. However, if the applied refractories have unevenness in the method of adding vibration or the amount of water added during construction, a small density portion may occur in the constructed refractory, or large bubbles may remain in the refractory. Or 20 to 3
It is often found that spaces with a narrow width of 0 mm or less remain unfilled and remain cavities. In this case, there may be partial differences in the corrosion resistance of the refractory, which may erode part of the refractory and shorten the service life of the ladle, or the iron shell of the ladle may melt, causing dangerous leakage of hot water. .

Further, it is necessary to carry a heavy vibrator to the site and install it during construction, and when the vibrator is operated, it is unavoidable that noise that deteriorates the working environment is generated. Generally, the more water added to a cast refractory, the better the flowability of the cast refractory, but the density of the applied refractory will be low, and the aggregate will cause segregation and heterogeneity. It is necessary to improve the fluidity by reducing the amount. Many proposals have been made to date for improving the fluidity of cast refractories and increasing the packing density.Add fumed silica or clay, or modify the surface of particles to make them hydrophilic. Typical examples are improving the dispersibility and selecting the type of dispersant.

Further, Japanese Patent Application Laid-Open No. 4-260673 proposes a cast refractory material which enables pumping by reducing the water absorption of aggregate particles.
Japanese Patent No. 08851 proposes concrete for construction, which has excellent fluidity, that is, self-leveling property (same as free-flow property), which can be poured by mixing cement made of spherical particles. There is. More recently, in the alumina spinel casting refractory used for ladle etc., the flowability and workability of the casting refractory can be improved, and the construction can be done without sacrificing the packing density and homogeneity, and the labor saving in construction. A castable refractory that has free-flowing properties and can be installed without vibration has been proposed (Japanese Patent Application No. 5-18068).
No. 9).

However, when the flow value under a vibration-free condition is about 160 to 170 mm, the flowability is about 20 to 30 m.
It may be difficult to pour into a space with a narrow width of m or less, and it may remain as a cavity, or the height of the surface of both sides of the refractory that has been constructed due to insufficient self-leveling properties may differ. Was insufficient. In addition, the addition of fumed silica and clay fine powder causes a problem of impairing the long-term volume stability when subjected to heat history, and when applied to a ladle, the degree of cracking of refractories increases, There was a problem that the expected durability could not be obtained.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to an alumina spinel pouring refractory used for a ladle and the like,
It is an object of the present invention to provide a flowable refractory material having a free flow property and excellent workability and durability. Further, the present invention is a casting refractory that is used as a casting material of a ladle, has improved conventional free-flow properties, is a casting refractory with better workability, and has a stable thermal long-term volume stability. It is an object to provide a cast refractory having excellent properties.

[0007]

The present invention has been made to achieve the above-mentioned object, and the composition for an alumina spinel castable refractory material of the present invention contains an alumina aggregate, a spinel and an alumina cement. 1 to 18% by weight of magnesia aggregate, 2 to 15% by weight of alumina particles having a particle size of 5 μm or less, and 8% of alumina cement.
After pouring into a cement flow cone according to JIS standard R-5201, which contains 15 to 15 wt% of the composition and is mixed with 6 wt% of water by external application, the flow cone is pulled out and left for 30 seconds without vibration. And a flow value of is 185 mm or more. Hereinafter,% means% by weight unless otherwise specified.

[0008]

In the composition for an alumina spinel pouring refractory for a ladle according to the present invention, alumina particles having a particle size of 5 μm or less are contained in the powder forming the joint portion of the refractory in an amount of 2 to 5% with respect to the composition.
15%, preferably 2-10% and 1 magnesia aggregate
By containing ~ 18%, the fluidity is remarkably improved. The content of magnesia aggregate in the composition is preferably 2 to 15%. Furthermore, CaO (calcium oxide) or Ca (OH) ₂ (calcium hydroxide) is used as C
By adding 0.02 to 0.15% in terms of aO, the fluidity of the kneaded material of the refractory composition mixed with water is significantly improved. Good fluidity is CaO or C
It is obtained by containing a (OH) _{2 in an} amount of 0.02% or more in terms of CaO, and if it exceeds 0.15%, the hardening time of the construction body is accelerated and the workable time of the kneaded clay is increased. It will tend to shrink. From the viewpoint of optimizing the fluidity of the kneaded material obtained by mixing the composition with water, the amount of CaO added is 0.0
It is preferably set to 5 to 0.1%. Long-term volume stability when the refractory is subjected to thermal history is obtained by containing 2% or more of alumina particles in addition to the magnesia aggregate, and when the content exceeds 15%, the structure And slag penetration resistance tend to be impaired, and corrosion resistance to basic slag will be reduced.

Further, the alumina cement blended in the composition is preferably fine in order to improve the fluidity, and expressed in terms of Blaine value of 5500 cm ² /
It is preferably g or more. Further, since the corrosion resistance of the refractory can be secured and the flowability of the cast refractory is good, the content of Al ₂ O ₃ in the alumina cement is 7
It is preferably 3% or more, and particularly preferably 78% or more. The blending amount of alumina cement is 8 to 15%, preferably 9 to
The content is 12%, but if it is less than 8%, the strength of the refractory to be constructed is poor, and if it exceeds 15%, physical properties such as corrosion resistance and volume stability of the obtained refractory tend to deteriorate. The preferred alumina spinel cast-in refractory composition of the present invention has a SiO ₂ component in the form of fumed silica or clay fine powder in the powder forming the bond of the refractory of 74 μm or less (passing through a 200-mesh sieve). Does not include. In conventional cast refractories, fumed silica and clay fine powder were blended in order to improve the fluidity, but by not containing these SiO ₂ components that lower the melting point, the fire resistance is improved and better corrosion resistance and baking resistance are obtained. The contraction property is secured.

As the alumina aggregate, there can be used crushed minerals such as commonly used gravel shale, crushed calcined bauxite, calcined alumina clinker, and fused alumina clinker. The fired spinel clinker and the electrofused spinel clinker that are commonly used can be used for the material, and the fired magnesia clinker and the electrofused magnesia clinker that are commonly used can be used for the magnesia aggregate. The amount of alumina containing the alumina aggregate is generally 55 to 75%, preferably 59 to 71%. If it is less than 55%, the slag penetration resistance deteriorates, and if it exceeds 75%, the heat retention of the refractory is reduced due to the high thermal conductivity of alumina, and the heat loss increases. The amount of spinel is generally 3 to 20.
%, Preferably 4 to 17%. If it is less than 3%, the corrosion resistance and slag penetration resistance deteriorate, and if it exceeds 20%, the slag penetration resistance and spalling resistance tend to deteriorate.

In the alumina spinel cast-in refractory composition of the present invention, the average particle size is usually 1 mm or less.
The non-spinelized MgO component is contained in the composition in the form of magnesia aggregate in an amount of 1 to 18%, preferably 2 to 15%, which ensures long-term volume stability of the refractory and ensures corrosion resistance and The fluidity of kneaded clay is improved. As for the effect of improving the corrosion resistance, if the magnesia aggregate exceeds 18%, the slag penetration resistance deteriorates. The presence of an appropriate amount of magnesia aggregate causes the following spinelization reaction with alumina particles during use to generate MgO + Al ₂ O ₃ → MgAl ₂ O ₄ spinel, which causes a slight expansion of the volume. Prevents shrinkage of refractories and ensures long-term volume stability.

Any additive can be further added to the composition for refractory cast alumina spinel of the present invention. For example, various surfactants and deflocculants can be used as a dispersant, but a sodium hexametaphosphate deflocculating agent that is particularly compatible with alumina cement can be used in the composition in an amount of 0.02 to 0. It is preferably contained in an amount of 15% by weight. If the sodium hexametaphosphate-based dispersant is added in an amount of 0.02% by weight or more, good fluidity can be obtained, and even if it is added in an excessively large amount, the effect is not increased, so the content is made 0.15% by weight or less.

In order for the cast-in refractory material to exhibit free-flow property, it is sufficient if the flow value after standing for 30 seconds without vibration using a JIS standard cement flow cone is 185 mm or more, and 6% by weight of water is applied outside. Is a small amount of water to be added to the kneaded clay of the poured refractory, so when the kneaded clay is poured, segregation of aggregate particles hardly occurs, density unevenness is small and bulk specific gravity is relatively large. Since it is a refractory material, it has good durability. In addition, the poured refractory kneaded material that exhibits free-flow property will naturally flow into the refractory kneaded material without using a vibrator as long as the refractory kneaded material is poured into the required place during construction. Since the kneaded clay has a good fluidity, air bubbles naturally float up and are discharged, and even a narrow gap is filled. Therefore, the labor for constructing the refractory material on the ladle and the like can be remarkably reduced, and further labor saving by using the construction machine for pumping pressure feeding becomes easy. Further, when the kneaded material of the cast refractory of the present invention is cast-molded using a vibrator, a refractory having a larger bulk specific gravity can be constructed by further reducing the amount of water to be added, and the durability of the refractory is further improved. It will be excellent.

The present invention improves the prior art in the flowability of the kneaded clay mixed with water, the volume stability of the refractory and the corrosion resistance in the composition for alumina spinel cast-in refractory, and in particular, it is 185 mm without vibration. Although it is characterized by exhibiting a high flow value as described above, preferred embodiments of the refractory composition for achieving this are summarized below. (1) Alumina-based aggregate 55-75% Spinel-based aggregate 3-20% Magnesia-based aggregate 1-15% Alumina cement 8-15% Alumina particles 2-5% with a particle size of 5μ or less Calcium oxide 0-0. A composition consisting of 15% optional components and the remaining amount, which is obtained by pouring a kneaded material obtained by externally mixing the composition with 6% water into a cement flow cone of JIS R-5201 and then removing the flow cone. A composition for an alumina spinel cast-in refractory, which has a flow value of 185 mm or more when left standing for 30 seconds under vibration. (2) CaO or Ca (O
The composition for an alumina spinel cast-in refractory according to any one of claims 1 to 4 or the above (1), wherein H) ₂ is contained in an amount of 0.02 to 0.15% in terms of CaO. (3) The content of Al ₂ O ₃ component in the alumina cement is 73% or more, and the Blaine value of the alumina cement is 5
The composition for an alumina spinel cast-in refractory material as described in (1) or (2) above, which is 500 cm ² / g or more. (4) Any one of claims 1 to 6 or the above (1) to (3)
A ladle obtained by pouring a kneaded material in which 6% or less of water is mixed into the composition for alumina spinel pouring refractory described in any one of 1.

[0015]

EXAMPLES Hereinafter, the alumina spinel type cast refractory material suitable for ladle according to the present invention will be specifically described by way of examples. These examples are examples of the present invention, and the present invention is The embodiment is not limited in any way. As an aggregate raw material, fused alumina clinker (coarse particles 3 to 10 mm: medium particles 3 mm or less), calcined alumina clinker (fine particles 0.3 mm or less), calcined spinel clinker (medium particles 1 mm or less) and calcined magnesia clinker (medium particles) 1 mm or less) was used. In addition, as the powder having a particle size of 74 μm or less that forms the bonding portion, the calcined alumina powder (43
.mu.m or less), calcined spinel powder (74 .mu.m or less) and fine alumina powder (5 .mu.m or less). Blaine value of 5500 to 1 manufactured by Denki Kagaku as alumina cement
Alumina cement with a content of Al ₂ O ₃ of 0000 cm ² / g of 80% was used, calcium oxide was used as a dispersant, and the composition for alumina spice pouring refractory for ladle shown in Table 1 was prepared. It was submitted to the test.

As for fluidity, the prepared composition for pouring refractory is put in a universal mixer, 6% of water is added to the kneaded mixture, and the kneaded material is poured into a flow cement of JIS cement, and the flow cone is pulled out. The spread (flow value mm) of the cast refractory was measured after standing for 30 seconds by vibration, and the results are summarized in Table 2. Here, the flow value is 100
mm means that the poured refractory does not flow at all. Next, the same kneaded clay with an inner size of 40 mm x 4
Pour into a 0 mm x 160 mm mold and remove from the mold,
A 40 mm × 40 mm × 160 mm test piece was obtained. The prepared test piece was dried at 110 ° C. for 24 hours, and then the bulk specific gravity, apparent porosity and compressive strength were measured. The results are also shown in Table 2.

Corrosion resistance test using a rotary erosion test furnace
Perform one test with mortar material between 6 test pieces
A test piece with a rim that is assembled into a hexagonal tubular body by filling
And CaO 54.8%, A as an erosion agent
l₂O₃ 28.5%, SiO₂ 8.6%, MgO
7.1%, Fe₂O₃ Basic slurry having a composition of 1%
Tested by inserting SS41 steel slab with the same weight as 0.6 kg
Rotate at 30 rpm with the body lying down,
Do not heat to 1650 ° C with acetylene burner flame from the side
It was held for 6 hours. Then, tilt it and melt it with the slag inside.
The cast iron was poured out, emptied, and allowed to cool. After cooling
Disassemble the hexagonal tubular test piece into the
The corrosion depth was measured, and the erosion depth C of the test piece of Example 10 was measured.₇The standard
As C ₇/ C_nEach refractory test prototyped with × 100
The corrosion resistance index of each piece was determined, and the results are also shown in Table 2.

As for the slag penetration resistance index, the maximum slag penetration depth is determined in the same manner as the corrosion resistance index, and the No. 7 The maximum slag penetration depth Pn of each refractory test piece for the maximum slag penetration depth P7 of the refractory test piece is calculated from the slag penetration resistance index P7 / Pn.
The slag penetration resistance index of each refractory test piece was similarly calculated in Table 2 and shown in Table 2. In the long-term volume stability test, a sample with dimensions of 40 mm × 40 mm × 80 mm was cut out from each of the poured test pieces, dried at 110 ° C for 24 hours, used as a measurement sample, and heated and held at 1600 ° C for 100 hours, and then left in a furnace. Chilled After cooling, the dimensions of the 80 mm long portion of each test piece are measured, and the dimension L _{b of} each test piece before heating and the dimension L _a after heating are calculated as (L _a −L _b ) / L.
The residual expansion rate (%) of each sample was determined by _b × 100.

Among these examples, Examples 1 to 6 are examples of the present invention, and Examples 7 to 9 are comparative examples. From these test results, the composition for an alumina spinel cast-in refractory material of the present invention has good fluidity of the kneaded material mixed with water, and shows a free flow property when 6% of water is externally mixed. It can be seen that the constructed refractory has better fluidity (free flow), corrosion resistance, and long-term volume stability than the conventional free-flowing alumina spinel refractory of Example 7. .

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Effects of the Invention] Since the flowability of the kneaded clay of the cast refractory obtained by adding water to the composition for alumina spinel cast refractory for ladle of the present invention is further improved, it is used for the lining construction of the ladle. In this case, by omitting the work of adding vibration to operate the conventional vibrator, removing the vibrator noise, and improving the filling property in a narrow space, you can always obtain a good construction body and improve the self-leveling property. As a result, it became unnecessary to refill the refractory and to construct it. In addition, the inclusion of magnesia aggregate ensures fluidity as well as long-term volume stability during use, and when used on the inner lining of a ladle, there are few cracks and slag resistance. Since the permeability is also excellent, the tendency of the durability to decrease due to peeling was remarkably improved, and the durability of the ladle was significantly improved. Further, since the pouring work by the pumping pressure feeding can be easily performed, the working environment can be improved at the same time. Since the workability is improved, the labor is saved, the work time is shortened, and the basic unit of the ladle is reduced at the same time, the industrial use effect of the composition for an alumina spinel pouring refractory according to the present invention is great.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Naotada Hoshi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) In-house Hirohisa Nakajima 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (72) Inventor Shintaro Sudo 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd.

Claims (6)

[Claims] 1. A composition comprising an alumina-based aggregate, spinel and alumina cement, wherein the magnesia-based aggregate is 1 to 18% by weight, and the alumina particles having a particle size of 5 μm or less are 2 to 2%.
A kneaded material containing 15% by weight and 8 to 15% by weight of alumina cement and mixed with 6% by weight of water to the composition was poured into a cement flow cone of JIS standard R-5201, and then the flow cone was pulled out. A composition for an alumina spinel cast-in refractory, which has a flow value of 185 mm or more when left for 30 seconds without vibration. 2. Alumina particles having a particle size of 5 .mu.m or less are 2-1.
The composition for an alumina spinel cast-in refractory material according to claim 1, containing 0% by weight. 3. The composition for an alumina spinel cast-in refractory material according to claim 1 or 2, wherein the composition does not contain fumed silica and clay. 4. The content of the Al ₂ O ₃ component in the alumina cement is 73% by weight or more, and the Blaine value of the alumina cement is 5500 cm ² / g or more.
The composition for an alumina spinel cast-in refractory according to any one of 1. 5. A calcium oxide or calcium hydroxide powder in terms of CaO of 0.02 to 0.15% by weight.
The composition for an alumina spinel cast-in refractory material according to any one of claims 1 to 4, which comprises. 6. The composition for an alumina spinel cast-in refractory material according to claim 1, which contains 2 to 15% by weight of a magnesia aggregate.