JP5663122B2 - Castable refractories for non-ferrous metal smelting containers and precast blocks using the same - Google Patents

Description

The present invention relates to a MgO—Al ₂ O ₃ —Cr ₂ O ₃ castable refractory for non-ferrous metal smelting vessels other than aluminum that requires corrosion resistance and spalling resistance, and a precast block using the same. .

Since slag in non-ferrous metal smelting excluding Al has a high carbon content in the metal, it is generally high FeO and has a low molar ratio of CaO / SiO ₂ . In such an operating environment for non-ferrous metal smelting vessels, magnesia-chromium basic brick is considered to be a suitable material and has been widely used for many years.

Conventionally, a large amount of irregular bricks has been used for non-ferrous metal smelting vessels. Typically, odd-shaped bricks were produced by hand-made molding.

As an alternative to mag-chromic basic bricks, Patent Document 1 discloses that CaO-MgO-ZrO ₂ refractory has excellent corrosion resistance and spalling resistance against FeO-SiO ₂ slag for non-ferrous metal smelting. It is disclosed to show.

Patent Document 2 proposes a non-ferrous metal refining refractory of Al ₂ O ₃ —Cr ₂ O ₃ —ZrO ₂ quality.

Patent Document 3 proposes a castable refractory for Al ₂ O ₃ —SiO ₂ —Si ₃ N ₄ nonferrous metal.

In recent years, MgO—Al ₂ O ₃ —Cr ₂ O ₃ -based materials have attracted attention. The prior art of the MgO—Al ₂ O ₃ —Cr ₂ O ₃ material related to the present invention is shown below.

Patent Document 4 has a chromium solid solution spinel clinker excellent in corrosion resistance to slag, and Patent Document 5 has a chromium solid solution spinel clinker excellent in corrosion resistance and spalling resistance in steel facilities. In the amorphous refractory, Patent Document 6, MgO—Al ₂ O ₃ spinel material and chromium oxide, which are excellent in corrosion resistance, penetration resistance and heat spalling property in the fields of steelmaking, cement and glass, are mainly used. Patent Document 7 discloses a refractory for a melting furnace in which Al ₂ O ₃ , MgO, Cr ₂ O ₃ and ZrO ₂ are combined, and Patent Document 8 discloses a melting furnace mainly composed of chromium oxide and spinel particles. Refractories for use are disclosed respectively.

Further, Patent Document 9 discloses a castable refractory using electrofused chromia as a main raw material related to the present invention.

JP-A-7-33518 JP-A-7-61858 JP 2000-1119070 A JP-A-5-254925 JP-A-6-287074 JP-A-7-300361 JP-A-11-199317 JP 2006-232653 JP 2003-342080 A

However, refractories disclosed in Patent Documents 1 and 2 because it contains ZrO _2, is not sufficient spalling resistance in relation to mineral transformation ZrO _2.

Since the castable refractories and precast blocks disclosed in Patent Document 3 are mainly made of an alumina / silica-based raw material, a low-melting material such as FeO in slag, FeO-SiO ₂ or FeO-Al ₂ O ₃ is used. Since it produces | generates, there exists a problem in corrosion resistance.

As disclosed in Patent Documents 4 and 5, a refractory material containing only a chromium solid solution spinel clinker has insufficient spalling resistance.

Since all MgO—Al ₂ O ₃ .Cr ₂ O ₃ materials disclosed in Patent Documents 6, 7, and 8 contain a relatively large amount of powdered chromium oxide, they are resistant to spalling. There is a problem. When the fine powdered chromium oxide reaches a high temperature, it coalesces with other fine powder raw materials and rapidly sinters, reducing the spalling resistance.

A material containing a large amount of electrofused chromia disclosed in Patent Document 9 has no problem in corrosion resistance, but is inferior in spalling resistance.

Therefore, the object of the present invention is to solve the above-mentioned problems of conventional refractories for non-ferrous metal smelting vessels, and to provide excellent corrosion resistance and spalling resistance to FeO-SiO ₂ slag for non-ferrous metal smelting. In addition to providing a material having the above, there is a need to eliminate the problem of increasing the production costs of conventional refractories for non-ferrous metal smelting vessels.

The present inventor has intensively studied and studied to solve the above problems. As a result, it is possible to obtain a material having excellent corrosion resistance and spalling resistance against FeO-SiO ₂ slag for non-ferrous metal smelting by combining the use of magnesia / alumina-based spinel raw material and electrofused chromia. I found.

(1) This invention is made | formed based on the said knowledge, The summary is as follows. Castable refractories mainly made of sintered and / or fused magnesia / alumina spinel and fused chromia.
(2) A precast block obtained by casting the castable refractory according to (1) above into a frame according to the purpose and application, followed by demolding, drying or further firing after curing.

The MgO—Al ₂ O ₃ —Cr ₂ O ₃ castable refractory according to the present invention and a precast block using the same are made of non-ferrous metals other than Al, which have high FeO and a low molar ratio of CaO / SiO ₂ . It shows excellent corrosion resistance and spalling resistance against smelting slag, so it can be replaced with conventional mug / chromic bricks. In addition, this precast block can be an alternative to conventional atypical hand-cast bricks.

Hereinafter, the present invention will be described in detail.

In the present invention, sintered and / or electrofused magnesia / alumina-based spinel material and electrofused chromia are used as main materials. A spinel having a theoretical composition of MgO and Al ₂ O ₃ in a molar ratio of 1: 1 is preferable. The theoretical composition does not contain free MgO and is difficult to slake. Corrosion resistance is good because it does not contain free Al ₂ O ₃ .

In the MgO—Al ₂ O ₃ —Cr ₂ O ₃ castable refractory and the precast block using the same, the blending amount of the magnesia-alumina-based spinel material is preferably 45 to 80% by mass. The blending amount of electrofused chromia is preferably 5 to 40% by mass. When the amount of electrofused chromia is 5% by weight or less, corrosion resistance is poor. If it is 40% or more, the corrosion resistance is good, but the spalling resistance and penetration resistance are lowered.

The castable refractory of the present invention comprises appropriately using chromium oxide fine powder, alumina fine powder, alumina cement, volatile silica, a dispersant, etc. in addition to the magnesia-alumina-based spinel raw material and electrofused chromia.

The said chromium oxide fine powder is not specifically limited, The thing of 97 mass% or more generally marketed purity is preferable. Those with low purity reduce the corrosion resistance. The blending amount of chromium oxide fine powder is preferably 15% or less. When it is blended by 15% or more, the spalling resistance is lowered.

The castable refractory of the present invention uses alumina cement as a binder. As the alumina cement, a commercially available general cement can be used. As for the compounding quantity of an alumina cement, 1-10 mass% is preferable. If it is 1% by mass or less, the strength is insufficient, and if it is 10% by mass or more, the CaO component increases and causes a decrease in corrosion resistance.

The castable refractory of the present invention uses a dispersant to increase the fluidity during construction or molding and to reduce the amount of water added. A dispersing agent is not specifically limited, For example, sodium tripolyphosphate, sodium hexametaphosphate etc. can be used.

Compared to the castable refractories made of chromium solid solution magnesia / alumina spinel clinker as the main material, the castable refractories using the magnesia / alumina spinel raw material and electrofused chromia material of the present invention as the main raw materials are of two types: Since each raw material is in a stable mineral state with a high melting point, both corrosion resistance and spalling resistance are high. In the case of chromium solid solution magnesia / alumina-based spinel clinker, the three components Cr ₂ O ₃ , MgO, and Al ₂ O ₃ act to have a lower melting point, so that the corrosion resistance is relatively inferior.

The particle size constitution of the castable refractory of the present invention may have a general particle size range in which 1.0 mm or more is 30 to 70% by mass and 0.1 mm or less is 25 to 60% by mass.

The castable refractory of the present invention can be applied by kneading the castable refractory by adding 3.5 to 7% by mass of water as an outer shell. It is desirable to use a vibrator during construction.

The castable refractory of the present invention is not only directly cast into a non-ferrous metal smelting vessel except for Al, but also cast into a frame of any shape according to the purpose and application, and after being cured, demolded, dried, Alternatively, it can also be used as a precast block obtained by further firing.

Hereinafter, the present invention will be described in detail with reference to examples.
A predetermined amount of water was added to and kneaded into a castable refractory compounded with each raw material component at a blending ratio shown in Table 2, and the mixture was cast into a 230 × 114 × 65 mm mold placed on a vibration table. The frame was removed after curing to obtain a molded body. The chemical components of the various raw materials used are shown in Table 1.

The molded body thus obtained was dried at 110 ° C. for 24 hours, and further fired at 1400 ° C. for 10 hours to obtain a specimen.

Table 4 shows the test results of mag-chromic fired bricks by hand-made molding conventionally used in non-ferrous metal smelting vessels as Examples 1 to 4, Comparative Examples 5 to 7, and Conventional Example 8.
The test method is as follows.

Bulk specific gravity and apparent porosity: Measured according to JIS R2205.

Compressive strength: measured according to JIS R2206.

Spalling resistance: The specimen was held for 15 minutes in a furnace maintained at 1500 ° C. from the tip of the 114 × 65 mm surface to one third, and then forced air cooled for 15 minutes at room temperature. This operation was repeated up to 40 times and evaluated by the number of times until peeling. The spalling resistance is better when the number of cycles until peeling is larger.

Erosion test and penetration test: A specimen is lined on the inside of a drum, and while the drum is rotated, the liner specimen is heated to 1400 ° C. with an oxygen / propane burner and heated. The slag for nonferrous metal smelting of C / S = 0.2 shown in Table 3 was thrown there, and the erosion test for 10 hours was done. The corrosion resistance of the specimen was evaluated by the thickness (mm) of the specimen reduced by erosion, and the penetration resistance was evaluated by the penetration depth of the slag. In addition, it showed with the index | exponent which makes the amount of erosion and the penetration depth of the prior art example 100 100. The smaller the index number, the better.

As shown in Table 4, Examples 1, 2, 3, and 4 in which spinel clinker and electrofused chromia are used in combination, both sintered and electrofused, have both good spalling resistance and corrosion resistance.

It turns out that the comparative example 5 which mix | blended only the spinel clinker has low corrosion resistance. It can be seen that Comparative Example 6 containing only electrofused chromia has very good corrosion resistance but has a problem in spalling resistance. It turns out that the comparative example 7 which uses a chromium solid solution spinel clinker as a main raw material is inferior to spalling resistance.

Conventional example 8, which corresponds to hand-cast molded mag / chromic bricks used in non-ferrous metal smelting furnaces for many years, is more resistant to spalling and corrosion than Examples 1, 2, 3 and 4. Both are bad.

The MgO—Al ₂ O ₃ —Cr ₂ O ₃ castable refractory of the present invention has good spalling resistance and high corrosion resistance against slag with high FeO and low basicity (low C / S). It can be suitably used as a refractory lining for non-ferrous metal smelting furnaces excluding Al. Moreover, if it is produced as a precast block, it can be replaced with a conventional hand-molded mug / black brick.

Claims (2)

Sintered magnesia-alumina spinel material and / or electrofused magnesia-alumina spinel material 45 to 80% by mass and electrofused chromia material 5 to 40% by mass, the balance being chromium oxide, calcined alumina, volatile silica A castable refractory material comprising at least one fine powder raw material selected from: alumina cement and a dispersant . A precast block obtained by casting the castable refractory according to claim 1 into a mold according to the purpose and application, and demolding, drying or further firing after curing.