JP6219764B2 - Lined casting material - Google Patents

Description

  The present invention relates to a lining casting material mainly used in a steelmaking processing apparatus.

  In steelmaking processing apparatuses, alumina-magnesia, alumina-spinel, or alumina-magnesia-spinel lining material is mainly used as a refractory that comes into contact with molten steel or slag. Among these, alumina-magnesia spinel has characteristics of both alumina-spinel and alumina-magnesia, and volume stability, corrosion resistance, and slag infiltration resistance show intermediate characteristics between the two materials. .

  Moreover, the technique which applies a hollow particle as a refractory raw material of these lining cast material is known. For example, Patent Document 1 discloses a technique in which hollow alumina particles are applied for the purpose of obtaining high slag resistance and low thermal conductivity in an alumina-magnesia lining casting material. Patent Document 2 discloses a technique of applying hollow particles to reduce the heat loss of molten steel in an alumina-spinel lining material.

  On the other hand, weight reduction may be required depending on the conditions in which the refractory is used. Lightening leads to a reduction in the weight of the refractory (construction weight), and when it is a molten steel pan, it can be expected to increase the amount of steel received by reducing the weight of the molten steel pan, and productivity It leads to improvement.

  Therefore, in order to reduce the weight of the lining casting material, it is conceivable to apply hollow particles that are lightweight aggregates. However, since hollow particles have lower strength than ordinary aggregates, erosion and infiltration are likely to proceed, and simply applying hollow particles leads to deterioration of corrosion resistance and heat spalling resistance.

JP 2011-241093 A Japanese Patent Laid-Open No. 4-149881

  The problem to be solved by the present invention is to reduce the weight and improve the corrosion resistance and thermal spalling property of the lining cast material.

  The present inventors examined the application of hollow particles in order to reduce the weight of the lining casting material. There are various types of hollow particles, but the alumina-magnesia, alumina-spinel, and alumina-magnesia-spinel lining material is hollow as disclosed in Patent Documents 1 and 2 above. Alumina particles and hollow spinel particles are the mainstream. Among them, the present inventors decided to select hollow spinel particles. This is because, when comparing the strength of hollow alumina particles and hollow spinel particles themselves, the hollow spinel particles show high strength, which is advantageous for erosion and infiltration, and superior in corrosion resistance and heat spalling resistance. It is. Further, when magnesia is contained in the blend, it is considered that the hollow alumina particles may cause further strength deterioration due to the reaction with magnesia in the hot state.

  On the other hand, Patent Document 2 describes that hollow alumina particles or hollow spinel particles may be used as hollow particles, and Table 1 of the same document describes an example using hollow alumina particles. Yes. Therefore, the present inventors examined the blending in which the hollow alumina particles were replaced with the hollow spinel particles in the blending shown in Table 1, and the heat-resistant spalling property was lowered.

  When the present inventors examined the cause of this heat-resistant spalling property fall, it was considered as follows. That is, in the lining cast material containing spinel, spinel dissolves FeO, so that it has high corrosion resistance and slag infiltration resistance against oxygen scrubbing and steelmaking slag, and has high hot strength, and residual expansion and contraction after receiving heat. It has small and high volume stability.

  However, when spinel fine powder is included in the blend and hollow spinel particles are used, the amount of spinel is excessively added and sintering becomes easy, so that the thermal spalling property is deteriorated. Therefore, it is necessary to adjust the spinel amount of the entire blend. However, if the hollow spinel particles are reduced, an ideal weight reduction cannot be expected. Therefore, it is desirable to reduce spinel fines.

  In view of the above, the present inventors selected hollow spinel particles as the hollow particles, and then restricted the spinel fine powder to suppress sintering and suppress a decrease in heat-resistant spalling properties.

That is, according to one aspect of the present invention, the magnesia raw material having a particle size of 75 μm or less is 3% by mass or more and 15% by mass or less, the spinel raw material having a particle size of 45 μm or less is 8% by mass or less, and the particle size is 0.2 mm. A raw material and a bond containing hollow spinel particles of 5.0% or less and 3% by mass or more and 15% by mass or less, with the remaining 90% by mass excluding other raw materials other than the refractory raw material having Al ₂ O ₃ as a main component A lining cast material comprising a refractory material comprising an agent is provided.

  According to the present invention, by using hollow spinel particles and limiting the amount of spinel fine powder (spinel raw material having a particle diameter of 45 μm or less), it is possible to reduce the weight of the lining casting material, as well as corrosion resistance and heat resistance. Polling property can be improved. Thereby, for example, in the molten steel pan, it is possible to increase the amount of steel received by reducing the construction weight, and it is possible to reduce erosion and separation due to slag, and to extend the life.

  The lining casting material of the present invention is constructed by adding an appropriate amount of construction water to a composition comprising a refractory raw material and other raw materials.

Here, the “refractory raw material” in the present invention refers to a magnesia raw material, a spinel raw material, hollow spinel particles, and the balance. The remaining 90% by mass or more is composed of a raw material mainly composed of Al ₂ O ₃ and a binder.

  As these refractory raw materials, general raw materials for lining casting materials can be used.

  Hereinafter, as an example, as a magnesia raw material, a raw material manufactured by electromelting or sintering and adjusted in particle size is used. It is preferable to use a magnesia raw material having high digestion resistance so that the magnesia raw material is digested during drying and cracks due to volume expansion do not occur.

As the spinel raw material, a MgO—Al ₂ O ₃ based compound having a chemical composition of MgO · Al ₂ O ₃ and a non-stoichiometric composition in which MgO or Al ₂ O ₃ is excessively dissolved in solid solution A raw material that is manufactured by electromelting or sintering and whose particle size is adjusted is used.

  As the hollow spinel particles, commercially available products obtained by electrofusion can be used.

As the raw material mainly composed of Al ₂ O ₃ , a raw material that is manufactured by electromelting or sintering and whose particle size is adjusted is used. The alumina raw material produced by electromelting or sintering and adjusted in particle size has an Al ₂ O ₃ content of 90% by mass or more, preferably 99% by mass or more. As the raw material mainly containing Al ₂ O _3, it may be used raw materials produced by the Bayer process which is called a calcined alumina.

  As the binder, alumina cement, magnesia cement or the like can be used, and alumina cement is particularly preferable from the viewpoint of imparting strength of the construction body.

As other raw materials, silica ultrafine powder and a dispersant are added. As the ultrafine silica powder, an amorphous SiO ₂ raw material having a particle diameter of 1 μm or less called silica flour, silica fume, fumed silica, micro silica, evaporated silica, or silica dust is used. Silica ultrafine powder is added for the purpose of preventing digestion of magnesia raw materials, reducing expansion due to spinel formation, and imparting creep properties during use, etc., but has the disadvantage that corrosion resistance is reduced by producing low melt. In the present invention, it is excluded from the refractory raw material.

  A dispersing agent is added in order to provide fluidity at the time of construction. Examples include sodium tripolyphosphate, sodium hexametaphosphate, polyacrylic acid, polyacrylic acid soda, polyacrylic soda, polycarboxylic acid, naphthalene sulfonic acid soda, and lignin sulfonic acid soda.

  In addition, for the lining material of the present invention, as other raw materials, curing agents such as boric acid, ammonium borate, slaked lime, sodium carbonate, lithium carbonate, foaming agent, organic fiber, Al powder, metal fiber, water reduction An agent, an AE agent, an antifoaming agent, a fluidity modifier, a magnesia digestion inhibitor, an explosion prevention agent, and the like can be appropriately added.

  In the present invention, the magnesia raw material, the spinel raw material, the hollow spinel particles, and the remaining refractory raw material are 100% by mass, and other raw materials such as silica ultrafine powder and dispersant are 100% by mass of the refractory raw material. It should be added as a hook.

Further, the present invention, since the material having a high corrosion resistance, high spalling resistance, raw material and binding agent mainly composed of Al ₂ O ₃ is preferably account for at least 95 wt% of the balance.

  The lining casting material of the present invention is a proportion of 100% by mass of the refractory raw material, and 3% by mass to 15% by mass of magnesia raw material having a particle diameter of 75 μm or less. When the particle diameter of the magnesia raw material exceeds 75 μm, the generation rate of spinel generated by the reaction between the magnesia raw material and the alumina raw material becomes slow, and the effect of improving the corrosion resistance by the reaction cannot be obtained. Further, if the magnesia raw material having a particle size of 75 μm or less is less than 3% by mass, the effect of improving the corrosion resistance cannot be obtained. On the other hand, if the magnesia raw material having a particle diameter of 75 μm or more exceeds 15% by mass, the amount of spinel generated is large, and the expansion of the lining casting material becomes large, which causes cracks and peeling. The addition amount of the magnesia raw material is preferably 5% by mass or more and 12% by mass or less.

  Moreover, the lining cast material of this invention is the ratio which occupies for 100 mass% of refractory raw materials, and the spinel raw material whose particle diameter is 45 micrometers or less is 8 mass% or less. When the particle diameter of the spinel material is more than 45 μm, the reaction with FeO is delayed, and the corrosion resistance is deteriorated. If the spinel raw material having a particle size of 45 μm or less exceeds 8% by mass, it becomes easy to sinter, leading to deterioration of the heat resistant spalling property. The addition amount of the spinel material having a particle size of 45 μm or less is preferably 5% by mass or less.

  Moreover, the lining cast material of this invention is the ratio which occupies for 100 mass% of refractory raw materials, and is 3 mass% or more and 15 mass% or less of hollow spinel particles whose particle diameter is 0.2 mm or more and 5.0 mm or less. If the hollow spinel particles have a particle diameter of less than 0.2 mm, the hollow spinel particles are also crushed, so the bulk specific gravity reduction effect cannot be obtained, and the effect of increasing the amount of steel received by reducing the construction amount is sufficiently obtained. Absent. If the particle diameter of the hollow spinel particles exceeds 5.0 mm, the pores inside the hollow spinel particles become large, and the corrosion resistance decreases. Further, when the hollow spinel particles are less than 3% by mass, the effect of reducing the bulk specific gravity cannot be obtained, and the effect of increasing the amount of steel received due to the reduction of the construction weight cannot be obtained sufficiently. If the hollow spinel particles exceed 15% by mass, the pores of the lining casting material become large, and the corrosion resistance decreases. The amount of hollow spinel particles added is preferably 5% by mass or more and 10% by mass or less.

  Table 1 shows the raw material structures of Examples and Comparative Examples of the present invention.

A test piece was prepared by adding a predetermined amount of water to the formulation shown in Table 1, kneading, pouring into a mold and drying. The raw material mainly composed of Al ₂ O ₃ is fused alumina having a particle size of 8 mm to 3 mm and 3 mm or less, the magnesia raw material is fused magnesia having a particle size of 75 μm or less, and the hollow particle is a particle size. Used were hollow spinel particles having a particle diameter of 0.2 mm to 5 mm or hollow alumina particles having a particle diameter of 5 mm or less. As a spinel material, a fused spinel fine powder having a particle size of 45 μm or less was used. In addition, alumina cement as a binder, silica flour as an ultrafine silica powder, and sodium polyacrylate as a dispersant were added.

  About the obtained test piece of each example, the amount of erosion infiltration, bending strength, bulk specific gravity, and heat-resistant spalling property were evaluated.

  The evaluation of the amount of erosion damage was carried out by using a converter slag and a slag rotation erosion test at 1650 ° C. for 10 hours. A value greater than 7 mm and not greater than 11 mm is indicated by Δ, and a value greater than 11 mm is indicated by ×. The erosion infiltration amount is an index of corrosion resistance, and the smaller the erosion infiltration amount, the higher the corrosion resistance.

  The bending strength was evaluated by curing a test piece having a shape of 40 × 40 × 160 mm, then removing the frame, drying at 110 ° C. for 24 hours, and measuring at 5 ° C. for 3 hours at 800 ° C. The smaller one was marked with x.

  The bulk specific gravity was evaluated by curing a test piece having a shape of 40 × 40 × 160 mm, then removing the frame and drying it at 110 ° C. for 24 hours, and the value measured based on JIS R 2205 is 2.65 or less. More than .65 and less than or equal to 2.75, ◯, greater than 2.75 and less than or equal to 2.85, Δ and greater than 2.85 are marked with ×.

  Evaluation of heat-resistant spalling property is carried out by curing a test piece of 230 × 114 × 65 mm shape, then removing the frame, drying at 110 ° C. for 24 hours, and heating and cooling using a test piece heat-treated at 1000 ° C. for 3 hours. Repeatedly, the occurrence of cracks was observed. Specifically, an operation in which a 114 × 65 mm surface was heated for 45 minutes in an electric furnace heated to 1200 ° C. and then air-cooled for 15 minutes using a fan was repeated 8 times. The case where some cracks occurred was indicated by Δ, and the case where large cracks occurred was indicated by ×.

  Comprehensive evaluation is for the amount of erosion infiltration, bending strength, bulk specific gravity, and heat spalling resistance. Is x.

  Examples 1 to 11 are examples of the present invention, and there is no x in the amount of infiltration, bending strength, bulk specific gravity, and heat resistance spalling, high corrosion resistance, high strength, low bulk specific gravity, and heat resistance. A lining cast material with high poling property was obtained.

  Comparative Example 1 was an example in which hollow alumina particles were used as hollow particles instead of hollow spinel particles, and the bending strength was low.

  In Comparative Example 2, the amount of spinel as a whole was smaller than that in Example 11, but since the amount of fused spinel fine powder was as large as 10% by mass, sintering became difficult and the spalling resistance deteriorated.

  Since the comparative example 3 had many hollow spinel particles, the amount of erosion infiltration deteriorated.

  Since the comparative example 4 had few hollow spinels, low bulk specific gravity (weight reduction) was not obtained.

  Since the comparative example 5 had few magnesia raw materials, spinel was not produced | generated and the amount of erosion infiltration deteriorated.

  Since the comparative example 6 had many magnesia raw materials, thermal expansion was remarkably large and the spalling resistance deteriorated.

Claims (1)

Hollow spinel particles having a magnesia raw material having a particle diameter of 75 μm or less, 3 mass% to 15 mass%, a spinel raw material having a particle diameter of 45 μm or less, 8 mass% or less, and a particle diameter of 0.2 mm to 5.0 mm. 3% by mass or more and 15% by mass or less, and the remaining 90% by mass excluding other raw materials other than the refractory raw material includes a refractory raw material comprising a raw material mainly composed of Al ₂ O ₃ and a binder. Cast material.