JP3400494B2 - Basic refractories for molten metal - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-ferrous metal refining furnace such as a copper flash smelting furnace or a copper converter, or a steel ladle, RH in a molten metal treatment apparatus.
Furnace, AOD furnace, on the molten metal for refractory to be used in the etc. steel-making secondary smelting furnace such as a VOD pot.

[0002]

As a refractory for molten metal, a magnesia-chromium (mag-chromo) basic refractory has a drawback that it is inferior in spalling resistance.
It has been widely used.

As a measure against this spalling resistance, some refractory materials of magnesia-carbon type or magnesia-lime-carbon type mixed with carbon have been adopted.

Further, in recent years, there has been an increasing demand for a so-called chromium-free material that does not contain chrome due to environmental problems, and a basic refractory having improved spalling resistance as well as chromium-free is an industrial product on August 26, 1991. Published by Technical Association Ceramic Data Book 1991 [Industry and Products No. 7
3].

However, the magnesia-carbonaceous refractory compounded with carbon has problems such as oxidation of carbon, carbon pickup to molten metal, and melting loss due to high FeO slag. There is a problem of digestion by lime, so it is a material that is difficult to use.

Therefore, it is possible to use alumina bricks, which are superior in spalling resistance to magnesia,
There is a problem that the corrosion resistance to FeO is significantly poor.

The ceramic data book disclosed is for cement kilns and cannot be used for molten metals.

Further, Japanese Patent Publication No. 4-56785 proposes a refractory material in which a binary clinker of CaO.ZrO ₂ and a magnesia raw material are combined, but expensive ZrO ₂ is used as the refractory raw material. However, the elastic modulus tends to be high, and the spalling resistance and the corrosion resistance are insufficient.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of conventional refractory materials for molten metal, and
aO ・ SiO ₂ —FeO slag and Fe for smelting non-ferrous metals
It is to provide a refractory having excellent corrosion resistance and spalling resistance with respect to O—SiO ₂ slag.

[0010]

The present invention has achieved the above object by combining a ZrO ₂ .CaO.MgO-based synthetic clinker containing ternary MgO as a third component with a magnesia raw material.

That is, the present invention is a synthetic ZrO ₂ .Ca
A carbon-free basic refractory obtained by combining an O.MgO-based clinker and a magnesia raw material, wherein the synthetic clinker has a molar ratio of CaO and ZrO ₂ of C
aO / ZrO ₂ is in the range of 0.4 to 1.0,
Further, the molar ratio of MgO to the total amount of ZrO ₂ and CaO is MgO / (ZrO ₂ + CaO), which is 0.3 to 3.0.

Further, the above-mentioned synthetic ZrO ₂ .CaO.M
When the amount of the gO-based clinker used is 10 to 70% by weight based on the total amount, the degree of achievement of the purpose is increased.

The particle size of the above synthetic ZrO ₂ .CaO.MgO clinker is preferably larger than 0.21 mm.

[0014]

[Function] The molar ratio of CaO / ZrO ₂ of the ZrO ₂ · CaO · MgO-based synthetic clinker and MgO / (ZrO ₂ + C
aO) molar ratio is within a specific range,
A refractory having excellent corrosion resistance and spalling resistance with respect to —SiO ₂ slag can be obtained.

If the ZrO ₂ .CaO.MgO-based synthetic clinker has a CaO / ZrO ₂ molar ratio of more than 1.0, the compound between ZrO ₂ and CaO is ZrO ₂ .C.
Since it exists only as aO, free CaO comes to exist, causing a digestion problem. Also, 0.
If it is less than 4, the amount of MgO-stable ZrO ₂ that is easier to destabilize is greater than that when stabilized with CaO, and the transformation of ZrO ₂ occurs during brick firing, resulting in a decrease in the strength of the brick. To do. Further, although the reason is not well understood, the corrosion resistance also decreases.

When the MgO / (ZrO ₂ + CaO) molar ratio of MgO to the total amount of ZrO ₂ and CaO is less than 0.3, the cause is not well understood, but the synthetic clinker particles when subjected to suraguatack Corrosion becomes faster and corrosion resistance decreases. Similarly, if the molar ratio is more than 3.0, it may be because the difference in the thermal expansion characteristics between the synthetic clinker and the magnesia raw material combined with the synthetic clinker becomes small, because the amount of MgO, which has a larger thermal expansion than CaO and ZrO ₂ , becomes relatively large. , The spalling resistance is reduced.

When the amount of the synthetic ZrO ₂ .CaO.MgO clinker used is less than 10% by weight, the amount of MgO in the brick is increased, the effect of adding the synthetic clinker is reduced, and the spalling resistance is deteriorated.

When the amount of the ternary synthetic clinker used is more than 70%, the homogeneity of the brick is promoted, the elastic modulus of the brick is increased, and the spalling resistance is deteriorated.

[0019]

EXAMPLES The compounding compositions shown in Tables 1 and 2 except for Comparative Example 1 and Comparative Example 2 were kneaded using an aqueous magnesium chloride solution. In the case of Comparative Example 1, a novolac type phenol resin was used, and in the case of Comparative Example 2, a modified phenol resin was used. Then, a shape of 230 × 114 × 85 mm was molded at a molding pressure of 2 ton / cm ₂ and fired at the temperature shown in the table.

[0020]

[Table 1]

[Table 2] As shown in the table, in the case of the embodiments of the present invention,
In the spalling test and the melt loss index showing corrosion resistance,
It turns out that it is superior to the comparative example.

On the other hand, the conventional carbon-containing products of Comparative Example 1 and Comparative Example 2 have no problem in spalling resistance, but are inferior in corrosion resistance to slag containing a large amount of FeO.

The magnesia-chromium material of Comparative Example 3 of the conventional product exhibits a relatively stable corrosion resistance, but has a problem in spalling resistance.

A comparison between Example 1 and Comparative Example 1 shows that when the binary synthetic clinker is added, the elastic modulus becomes high, the spalling resistance is poor, and the corrosion resistance is not sufficient.
By adding the ternary synthetic clinker of the present invention, corrosion resistance and spalling resistance could be satisfied at a high level.

A comparison between Example 2 and Comparative Example 5 shows that when the amount of MgO in the ternary synthetic clinker falls below the specified lower limit, the elastic modulus increases, spalling resistance decreases, and corrosion resistance also decreases. There is. Therefore, it is necessary to exceed the specified lower limit amount.

Comparison between Example 3 and Comparative Example 6 shows that when the amount of MgO in the synthetic clinker exceeds the specified upper limit, the amount of MgO in the clinker becomes too large and the spalling resistance is lowered. .

By comparison between Example 4 and Comparative Example 7, if the amount of CaO in the ternary synthetic clinker is less than the specified lower limit, the cause is not well understood, but the corrosion resistance decreases.
Therefore, it is necessary to exceed the lower limit amount. However, if the amount exceeds the upper limit, free lime will be present in the clinker and the digestion resistance of the clinker itself will be greatly reduced, which is a fatal drawback when used as a raw material for amorphous refractory.

The compounding compositions shown in Example 1 and Comparative Example 4 were externally coated with 2% alumina cement as a binder.
Knead as added castable compound, 350 × 2
It was cast-molded using a rod-shaped vibrator in a mold of 00 × 200 mm. After drying at 110 ° C for 24 hours, test the sample for erosion test at 1500 ° C considering the heat load during use.
A sample for a spalling test was taken after baking at × 5H.

C / S = 3, FeO in * l and * 2 of Table 1
= 20%, a comparative test of the binary synthetic clinker additive product and the ternary synthetic clinker additive product was performed. As a result, in the spalling test, no peeling occurred in the Example 1 base product even after 6 times, whereas in the Comparative Example 4 base product, peeling occurred 3 times.

In the erosion test, when the melt loss index of Comparative Example 4 base product is 100, the melt loss index of Example 1 Base product is 5
It was 2.

Therefore, it can be seen that the addition of the ternary synthetic clinker of the present invention made it possible to satisfy both the spalling resistance and the corrosion resistance of both baked bricks and amorphous products. Of course, even if the ternary synthetic clinker is added, a sufficient effect cannot be obtained unless the amounts of MgO and CaO in the clinker are within the specific range.

According to the comparison between Example 5 and Comparative Example 8, unless the amount of the ternary synthetic clinker used is 10% by weight or more, the spalling resistance is lowered and the corrosion resistance to extremely low C / S slag is also lowered. .

From the comparison between Example 6 and Comparative Example 9, it can be seen that the spalling resistance is significantly lowered unless the amount of the ternary synthetic clinker used is 70% by weight.

The formulations shown in Tables 1 and 2 are used according to the shape of the brick at the end of use (the copper smelting furnace slag line for copper> the ladle for steelmaking> the RH furnace tank bottom in this order).
Other conditions were trial-produced under the same conditions as those shown in the above embodiment. The results of using the actual furnace are shown in Table 3.

[0034]

[Table 3] In the case of the example of the present invention, the durability is excellent as compared with the comparative example, while the carbon-containing material as in the comparative example 1 causes a problem of C pickup and has a sufficient durability. is not.

Comparison between Comparative Example 3 and Comparative Example 4 showed that the addition of binary synthetic clinker could achieve chromium-free conversion, but no improvement in durability was observed. By adding MgO to the binary synthetic clinker to form the ternary synthetic clinker, a sufficient effect of improving the durability was obtained. However, according to Comparative Example 9, if added more than necessary, durability deteriorates.

In the above examples, the method of synthesizing the ternary synthetic clinker was shown only for the electrofused product, but it is not limited to this, and attention should be paid to the direction of eliminating the presence of free lime in the synthetic clinker produced. It is difficult if the particle size of the raw material used (as small as possible) and the dispersion of each raw material are taken into consideration, but it is possible to use the sintering method.

Refractory heat treatment temperature is 175 for fired bricks.
Although only 0 ° C. and 110 ° C. in the amorphous form are exemplified, the invention is not limited to these and may be appropriately selected according to the use conditions.

The molding method and the molding pressure are not limited to the examples, and may be appropriately selected according to the use conditions and the shape of the refractory material. For example, in the molding method, oil press,
Various methods such as a friction press, a static pressure press, a rammer stamp press, an atmospheric pressure casting method, a reduced pressure casting method, a bar-shaped vibrator, and a vibrating table can be used.

The binder is also not particularly limited, and a substance containing a large amount of SiO ₂ or Al ₂ O ₃ basically acts as a flux on the target material of the present invention, and basically the material of the present invention is If it is basic, it may be appropriately selected in consideration of use conditions, refractory shape, season at the time of production, and the like.

The purity of magnesia to be combined is not particularly limited, but the amount of SiO ₂ and Al ₂ O ₃ is not preferable because it is likely to act as a flux as a result, but unnecessarily high purity. Since the cost is simply increased if the target is made higher, MgO may be appropriately selected from the range of 90 to 99.7 wt% according to the use conditions and the manufacturing method.

[0041]

According to the present invention, ZrO ₂ -CaO-M
By combining the gO ternary synthetic clinker and the magnesia clinker, it has become possible to achieve chromium-free and achieve both high corrosion resistance and high spalling resistance.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C04B 35/48 C04B 35/00-35/22

Claims (2)

(57) [Claims] The method according to claim 1] Carbon Synthesis _ZrO 2 · CaO · MgO-based combined clinker and magnesia feedstock ing
A basic refractory which does not contain , wherein the synthetic clinker has a molar ratio of CaO and ZrO ₂ of CaO / ZrO.
₂ is in the range of 0.4 to 1.0, and Mg
The molar ratio of O to the total amount of ZrO ₂ and CaO is Mg
O / (ZrO ₂ + CaO), a basic refractory for molten metal, which is 0.3 to 3.0. _{2. The} synthetic ZrO _{2 according to} claim 1.
-A basic refractory for molten metal in which the amount of CaO / MgO-based clinker used is in the range of 10 to 70% by weight based on the total amount.