JP2001114571A - Castable refractory for trough of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an executable castable refractory for a trough of a blast furnace having high tolerance. SOLUTION: This castable refractory for the trough of the blast furnace is obtained by adding 0.5-10 mass % of an aluminum powder and/or an aluminum alloy powder and a colloidal silica as a binder in an amount of 0.1-2 mass % expressed in terms of SiO2 to 100 mass % of a refractory aggregate composition consisting essentially of 1-50 mass % of silicon carbide, 1-20 mass% of carbon and the balance of alumina and/or an MgO.Al2O3-based spinel. The castable refractory for the trough of the blast furnace is suitable especially as a metal line of the trough of the blast furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a castable refractory used as a lining of a blast furnace gutter.

[0002]

2. Description of the Related Art A blast furnace gutter has a role as a passage for hot metal discharged from a blast furnace to reach a ladle, a mixed iron wheel and the like. In recent years, castable refractories have been used for the lining in place of bricks in view of workability (Japanese Patent Laid-Open No. 5-339065).

[0003]

However, castable refractories for blast furnace gutters have never had a sufficient service life due to the severer operation of the blast furnace. There is a strong demand for materials having higher durability than conventional materials, for the purpose of reducing the amount of water.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a castable refractory for a blast furnace gutter which meets the above-mentioned requirements. The feature is that, with respect to 100% by mass of a refractory aggregate composition mainly composed of 1 to 50% by mass of silicon carbide, 1 to 20% by mass of carbon, and the balance being alumina and / or MgO.Al ₂ O ₃ spinel, It is a castable refractory for a blast furnace gutter which is obtained by adding 0.5 to 10% by mass of aluminum powder and / or aluminum alloy powder and 0.1 to ₂ % by mass of colloidal silica as a binder in terms of SiO.

[0005] A conventional castable refractory for a blast furnace (hereinafter referred to as a gutter material) has a composition of alumina and / or Mg.
O.Al ₂ O ₃ -based spinel (hereinafter referred to as spinel) is combined with silicon carbide and carbon, and alumina cement is added as a binder.

[0006] Silicon carbide has high corrosion resistance to blast furnace slag, has the effect of spalling resistance due to high thermal conductivity and low thermal expansion, and is indispensable as a constituent material of the gutter material.

[0007] The blast furnace gutter has two locally damaged portions generally called slag lines and metal lines in its height direction. Of these, the metal line is located near the slag-pig interface, and the damage factors are blast furnace slag and slag
It is considered to be the erosion effect of FeO generated near the interface of pig iron.

[0008] SiC + 3FeO between silicon carbide and FeO
→ An oxidation / reduction reaction of SiO ₂ + 3Fe + CO occurs.
When silicon carbide is decomposed by this reaction, the effects of corrosion resistance and spalling resistance of silicon carbide are lost. Therefore,
In order to suppress damage to the metal line portion of the gutter material, it is effective to prevent a reaction between silicon carbide and FeO.

[0009] The gutter material of the present invention is added with aluminum powder and / or aluminum alloy powder (hereinafter referred to as Al metal). When Al metal is added, the main component Al reacts with FeO when the gutter material is used, and becomes Al ₂ O ₃ . At this time F
eO is reduced and changes to Fe having no erosion action (2Al + 3FeO → Al ₂ O ₃ + 3Fe). As a result, the reaction between silicon carbide and FeO is suppressed, and the durability of the gutter material is improved.

[0010] The above reaction is prior to the reaction between SiC and FeO.
SiO2 by the reaction of SiC and FeO₂of
Al is generated from Al metal₂O
₃Is a highly refractory substance,
The addition of Al metal does not lower the corrosion resistance.

However, when alumina cement is used as a binder as in the case of conventional materials, the p
Since H becomes high, Al metal reacts with construction water to change to aluminum hydroxide, cannot remain as Al metal in the material, and exhibits the effect of the present invention of suppressing the reaction between silicon carbide and FeO. Can not.

[0012] The gutter material of the present invention improves the durability by adding Al metal by using colloidal silica instead of the conventional alumina cement as the binder. Also,
The effect is remarkably exhibited in the metal line even in the gutter material of east and west.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The silicon carbide used in the present invention mainly has an effect of slag resistance. If the proportion of the composition in the refractory aggregate is less than 1% by mass, there is no slag resistance effect. 50
If the content exceeds the mass%, fluidity during construction of the gutter material is reduced, and a dense construction body cannot be obtained.

[0014] The particle size of silicon carbide is not particularly limited. But,
When the use amount of silicon carbide is as small as 1 to 30% by mass, for example, 0.5%
It is preferably mainly composed of fine particles of not more than mm.

[0015] Carbon has the effects of spalling resistance, slag penetration prevention and hot metal penetration prevention. Specific examples include pitch, carbon black, artificial graphite, phosphorous graphite, earthy graphite, coke, and anthracite. The proportion of the refractory aggregate composition is
If the amount is less than 1% by mass, the effect of carbon cannot be obtained, and
If it exceeds 300, the corrosion resistance will decrease due to oxidation.

[0016] Alumina and spinel have effects such as volume stability and corrosion resistance. Specific examples of alumina include sintered alumina, fused alumina, shale, bauxite, and the like. Among them, synthetic products of stable quality such as sintered alumina and electrofused alumina are preferable. Calcined alumina may be used for the fine powder portion.

[0017] Specific examples of the spinel are a sintered spinel or an electrofused spinel. From an economical point of view, spinel slag produced as a by-product during vanadium refining may be used. A calcined spinel may be used for the fine powder portion. The component (MgO.Ai ₂ O ₃ ) of the spinel is not limited to the theoretical value of the spinel, and may be, for example, an alumina rich material having a large Al ₂ O ₃ value.

The proportion of spinel and / or alumina in the refractory aggregate depends on the proportion of other refractory aggregates.
30-98 mass% is preferred.

As long as the refractory aggregate does not impair the effects of the present invention, besides those mentioned above, pyroxene, silica, mullite, kyanite, andalusite, magnesia, magnesia
You may combine calcia, zircon, zirconia, chromite, silicon nitride, chromium oxide, etc.

[0020] Al metal reacts with carbon at a high temperature during use of the gutter material to form aluminum carbide, thereby improving the structural strength of the gutter material. Further, it acts to suppress the reaction between the SiC-FeO components and prevents a reduction in corrosion resistance. This effect can be obtained with any of aluminum powder and aluminum alloy powder. Specific examples of the aluminum alloy powder include an aluminum-magnesium alloy and an aluminum-silicon alloy.

[0021] Al metal is added as fine powder to enhance the reactivity. For example, it is a fine powder containing 50% by mass or more having a particle size of 0.1 mm or less. If the addition ratio of Al metal to 100% by mass of the refractory aggregate is less than 0.5% by mass, the corrosion resistance of the gutter material is reduced. If it exceeds 10% by mass, sintering becomes excessive and the spalling resistance is poor.

[0022] Colloidal silica as a binder is a colloid solution in which ultrafine particles of silicic anhydride are dispersed in water.
The content of the silicic anhydride is preferably 15 to 30% by mass, the pH is 4 to 10, and the particle size of the silicic anhydride is 5 to 50 nm.

When the proportion of colloidal silica added to 100% by mass of the refractory aggregate is less than 0.1% by mass in terms of SiO _{2 of} colloidal silica, the strength of the construction body is insufficient. If it exceeds 2% by mass, the amount of the SiO ₂ component with respect to the gutter material becomes excessive, resulting in a decrease in corrosion resistance.

[0024] Although the gutter material according to the present invention is subjected to heating such as heating and drying after construction, sufficient construction body strength can be obtained. However, if a hardening agent is further added, the construction body strength is exhibited without heating, and construction is performed. It is preferable in terms of properties.

Specific examples of the curing agent include magnesium sulfate,
Salts of polyvalent metals such as alum, and salts of monovalent metals such as salt, sodium sulfate, sodium phosphate, and sodium silicate. Fire resistant aggregate
The amount of the curing agent added to 100% by mass is preferably 3% by mass or less. More preferably, it is 0.05 to 1% by mass.

[0026] In addition to the above-mentioned refractory aggregates, binders and curing agents, if necessary, dispersants, drying accelerators, metal fibers, organic fibers, salamic fibers, oxidizing agents known as additives for castable refractories. Inhibitors, thickeners, volatile silica, refractory coarse particles and the like may be added.

The dispersant imparts fluidity during construction of the refractory. Specific examples include sodium tripolyphosphate, sodium hexametaphosphate, sodium ultrapolyphosphate, sodium acid hexametaphosphate, sodium borate, sodium carbonate, inorganic salts such as polymetaphosphate, sodium citrate, sodium tartrate,
Sodium polyacrylate, sodium sulfonate, polycarboxylate, β-naphthalene sulfonate, naphthalenesulfonic acid and the like. The amount of addition is about 0.01 to 1% by mass based on 100% by mass of the refractory aggregate composition.

[0028] Examples of the drying accelerator include organic fibers, foaming agents, and basic aluminum lactate. Specific examples of the organic fibers are polymer organic fibers such as vinylon (including polyvinyl alcohol), rayon, polyester, nylon, polypropylene, and polyethylene.

The antioxidant is a metal powder such as silicon and magnesium, a boride, a glass powder and the like. The thickener is clay, bentonite, CMC or the like.

[0030] The refractory coarse particles have a role of preventing the growth of cracks generated in the refractory structure. Particle size of refractory aggregate is generally 10m
In the range of less than m, the particles are adjusted to coarse particles, medium particles, and fine particles, but the refractory coarse particles have a larger particle size and are clearly distinguished from the refractory aggregate.

[0031] The particle size of the refractory coarse particles has a balance with the particle size of the refractory aggregate, but is preferably 10 to 50 mm. As the material, alumina, spinel, silicon carbide, or the like, or refractory waste material containing these as a main material can be used. The percentage is
It is 40% by mass or less, preferably 5 to 30% by mass, based on 100% by mass of the refractory aggregate composition.

[0032] In the construction of the gutter material of the present invention, as in the case of the conventional material, construction water is externally added to about 4 to 8% by mass, mixed, and then poured using a core. At the time of construction, it is usually vibrated by a vibrator to enhance the filling property.

The material of the present invention is particularly preferable for metal lines among gutter materials. Therefore, the material of the present invention may be used only for the lining of the metal line portion, and the slag line portion may be made of another material. In addition, it can be used for both new lining of gutters and rehabilitation after gutter use.

[0034]

EXAMPLES Table 1 shows the compositions and test results of Examples of the present invention and Comparative Examples. The test method is as follows.

Corrosion resistance: 5 to 6% by mass of construction water was added to each gutter material composition, and after kneading, the mixture was poured into a vibrating mold and molded. Next, curing and drying were performed to obtain a test sample.

Each sample was lined in a high-frequency furnace and the corrosion resistance was measured. A high-frequency furnace, in a furnace pig iron (including 33.5 wt% CaO:: 43.4 wt%, SiO ₂₎ = blast furnace slag
An erosion agent consisting of 30: 1 was melted at 1550 ° C. The numerical value of the corrosion resistance is shown as an index with the erosion dimension of Comparative Example 1 being 100, and the smaller the numerical value, the better the corrosion resistance.

Actual machine test: Thickness 35
After pouring in at a distance of 0 mm, and after passing 45,000 tons of iron, the wear dimension of the maximum wear area was measured and the wear rate (mm / 1000
t passing iron). If the test values are not described,
Not tested.

As the colloidal silica, Snowtex C (SiO ₂ : 20% by mass) manufactured by Nissan Chemical Industries, Ltd. was used.

[0039]

【table 1】

As shown by the test results in the table, all of the examples of the present invention show good corrosion resistance, and the effect is also confirmed from the results of actual machine tests.

On the other hand, Comparative Example 1 in which alumina cement was used as a binder, Comparative Example 2 in which the addition amount of Al metal was large, Comparative Example 3 in which the addition amount of colloidal silica (solid basis) was large, and fire-resistant aggregate Comparative Example 4 containing no carbon and Comparative Example 5 containing no Al metal were all inferior in corrosion resistance.

In Comparative Examples 6 and 7, Al metal was added, but no silicon carbide was used for the refractory aggregate. Here, the binder is colloidal silica in Comparative Example 6, Comparative Example 7 is alumina cement, and Comparative Example 5, Comparative Example 6, and Comparative Example 7 do not show much difference in corrosion resistance, so that the use of colloidal silica in the present invention improves the corrosion resistance. It is confirmed that the effect is exhibited only in a material using Al metal and silicon carbide.

Further, as shown in an actual machine test, the gutter material of the present invention exerts its effect in a metal line.

[0044]

The gutter material of the present invention has excellent corrosion resistance and durability as shown in the test results of the above examples.
As a result, the gutter material of the present invention contributes to efficiency of tapping work, reduction of refractory unit consumption, and the like, and has extremely high industrial value.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) F27D 1/00 F27D 1/00 N

Claims (2)

[Claims] 1 to 50% by mass of silicon carbide, 1 to 20% by mass of carbon, and the remainder is alumina and / or MgO.Al ₂ O ₃
0.1 to ₂ % by mass of colloidal silica as a binder and aluminum powder and / or aluminum alloy powder of 0.5 to 10% by mass with respect to 100% by mass of a refractory aggregate composition mainly composed of a spinel. Castable refractory for blast furnace gutter added. 2. The castable refractory for a blast furnace gutter according to claim 1, wherein a hardening accelerator is added in an amount of 3% by mass or less to 100% by mass of the refractory aggregate composition.