JPH04193773A - Castable alumina-spinel refractory - Google Patents

Abstract

PURPOSE:To improve the hot strength of castable alumina-spinel refractories contg. a prescribed amt. of MgO-Al2O3 spinel and to inhibit the penetration of slag and molten pig iron by blending the refractories with a specified amt. of A(l)N and/or BN. CONSTITUTION:Castable alumina-spinel refractories contg. 10-70wt.% MgO-Al2O3 spinel are produced and blended with 1-10wt.% at least one of AlN and BN. A surface coated with the resulting castable refractories is made hardly wettable with slag and molten pig iron and structural spalling can be prevented. Since AlN and BN are hardly oxidizable, oxidation resistance can be rendered. When a molten pig iron vessel is lined with the refractories, the service life of the vessel can considerably be prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to refractories, and particularly to alumina-spinel castable refractories.

[Conventional technology]

In recent years, due to the demand for higher grade steel products and slag-free operations in steel plants, for example, hot metal from blast furnaces is being desiliconized, dephosphoroused, It has become common to carry out pre-treatment such as desulfurization. For example, in the case of desulfurization, such pre-treatment involves adding a desulfurizing agent such as a Ca-based compound (CaC2, C20) into hot metal together with a gas such as oxygen. A method of blowing through the air is used.

Along with these treatments, refractory linings for containers such as pig iron trucks are required to have corrosion resistance against substances other than slag, and are considered to have better corrosion resistance in place of conventional alumina-based and high-alumina-based castable refractories. alumina (Ar103) - silicon carbide (S i C) - carbon (
C) quality refractory bricks, alumina-silicon carbide castable refractories, alumina-silicon carbide-carbon castable refractories, and alumina-spinel castable refractories are used.

[Problem to be solved by the invention]

However, the above-mentioned alumina-silicon carbide castable refractories and alumina-silicon carbide-carbon castable refractories are used for parts such as container lining +4 or pig iron receiving I, and do not have a certain durability. However, is it possible that the cracks occur when the structure changes due to a reaction with the treatment agent added to the hot metal for the pretreatment mentioned above? It is unavoidable that it will be damaged by structural spalling leading to separation (Ml]), direct corrosion by low basicity slag and processing agents, and there is dissatisfaction with the usability of the surface.

In addition, in the above alumina-spinel castable refractory, the MgO-Δp203 spinel blended in the raw material is Fe
, 0. Alumina-Silicon Carbide-Carbonaceous Castaple Refractory However, there is still room for improvement.

The present invention has been proposed in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a castable surface for lining a saw-toothed pig-wheel vehicle, etc., which has excellent corrosion resistance and spalling resistance.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following means. That is, Mg0-Al2O° spinel is 10
The alumina-spinel castable refractory contains 1 to 10% by weight of at least one of aluminum nitride and boron nitride.

[For production]

In the above configuration, Mg0-Aff contained in the alumina-spinel castable refractory to which the present invention is applied
z Oz spinel is spinel with theoretical composition (A42037
2%, Mg028%), but it is not limited to this composition, for example, A6z0360%, Mg028%).
Mg0-Al2O3 spinel having a composition such as g040%, Δ12o, 90%, or Mg010% can also be used, and both fused spinel and sintered spinel can be used.

The blending amount of the above Mg0-AI2203 spinel is 10-7
0% by weight is preferable; if it is less than 10% by weight, the construction body cannot be sufficiently densified, and if it exceeds 70% by weight, there will be a relative shortage of alumina raw material, and the carbon content in the slag will be reduced.
ab, 5in2 becomes difficult to capture, and corrosion resistance decreases.

Further, as the alumina raw material, sintered alumina, fused alumina, etc. with a purity of 95% or more can be used, and the particle size is appropriately adjusted and blended.

By adding at least one of aluminum nitride and boron nitride to the alumina-spinel castable refractory that exhibits a certain slag penetration suppressing effect, the surface on which the castable refractory is constructed can be wetted with slag and hot metal. This structure suppresses the occurrence of spalling. In addition, aluminum nitride J1 and boron nitride are relatively oxidizable and have the effect of imparting oxidation resistance.

- The blending amount of aluminum nitride and boron nitride is desirably 1 to 10% by weight of the total constituent raw materials of the aluminous spinel-1-Yastapul refractory, and if the blending amount is less than 1% by weight, it will penetrate into the slag. The suppression effect is not sufficient, and 1
If it exceeds 0% by weight, the corrosion resistance against slag, hot metal, etc. will be rather reduced. Aluminum nitride and boron nitride can be used together in any proportion within the above range.

Other substances to be added to the alumina-spinel castable refractory to which the present invention is applied include alumina cement, silica sol, alumina sol, etc. as a binder, ultrafine silica powder for workability and strength, etc. Ultrafine alumina powder, etc., i4 scale graphite for the purpose of improving spalling properties, pinches, etc., metals such as metallic silicon, ferrosilicon, etc. for the purpose of preventing oxidation, improving sintering strength, and improving hot strength. It is also possible to add any amount.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on Examples.

Examples j to 3 and Comparative Example 1.2 were prepared using the raw materials and binders shown in the upper column of Table 1.

In Examples 1 to 3, one or both of aluminum nitride and boron nitride were blended, and the other raw material compositions were almost the same as in the comparative example.

The lower column of Table 1 shows the measurement results of tests conducted on each of the obtained samples.

As is clear from the table, the erosion ratio of the example is the same as that of the comparative example 1.
Although there is no noticeable difference from 2 to 2, the slag penetration ratio is reduced by 20 to 30%.

In addition, the hot strength and cold strength of the examples are significantly higher than those of the comparative examples, and the superiority is particularly remarkable in the hot strength of 1400°C. It has been demonstrated that the cohesive strength of the tissue has been improved.

Furthermore, the number of times until peeling in the spalling test was 30 to 50% longer than that of the comparative example, indicating that the resistance to repeated cycles of heating and cooling was also significantly increased.

The details of the above test are as follows.

■Slag test The sample was immersed in a mixture of pig iron and pretreated slag at 1550°C, and after rotating for 5 hours (replacing the slag every hour), the erosion area and slag permeation area of the cross section of the sample were measured, respectively. It is expressed as a relative value with Comparative Example 1 set as 100.

■Hot bending strength measurement test ASTM C383-766, 1m, :XOO℃
, shows numerical values measured at a temperature of 1200°C.

■Cold bending strength measurement test JIS R2213-78, 2 at 110'c
After curing for 0 hours, the values are shown after firing at 1400°C for 3 hours.

■Compressive strength JIS R2206-77, 20 at 110'C
The values are shown after curing for 3 hours and firing at 1400'c for 3 hours.

(2) Spalling test A sample was heated to 1300'C, air-cooled, and returned to room temperature, and the number of cycles until the sample surface structure peeled off was measured.

Furthermore, in addition to the above tests, when the alumina-spinel castable refractories of Example 1 and Comparative Example 1 were applied to the pigtail receiving port of a pig iron mixer car, the number of service life of the comparative example was 100 charges (hereinafter referred to as ch). In Example 1, the channel was improved to 160ch.

In addition, the material of Example 2 was used for the hot metal pretreatment lance,
Comparison was made with Comparative Example 2. Comparative Example 2 had a service life of 4 channels, but Example 2 showed a 6 channel service life.

From the results of actual machine use described in Section 2, it has been found that when the embodiments of the present invention are applied to areas where corrosion resistance is required, such as the pigtail receiving port of a pig iron mixer car, corrosion resistance can be improved by suppressing penetration of slag and hot metal. This is considered to be a factor, and it is judged that when the present invention was applied to parts where heating and cooling are repeated, such as the latter hot metal pretreatment lance, the effect of improving spalling resistance was achieved. can.

<Left below> ? 1. 1=: Gap [Effect of the Invention] As described above, according to the present invention, by blending aluminum nitride and boron nitride alone or in combination with alumina spinel castable having relatively high corrosion resistance,
It is possible to improve hot strength and suppress the penetration of slag and hot metal.As a result, when used for the lining of a hot metal conveying container, etc., a significant improvement in life can be expected.

Claims (1)

[Scope of Claims] [1] An alumina-spinel castable refractory containing 10 to 70% by weight of MgO-Al_2O_3 spinel, containing 1 to 10% by weight of at least one of aluminum nitride and boron nitride. Characteristics of alumina-spinel castable refractories.