JPS6053835B2 - Spraying repair method for industrial kiln - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of repairing worn parts of an industrial furnace lined with an acidic refractory by firmly spraying a basic sprayed refractory thereon.

Conventionally, acidic refractories such as waxite refractories have been used for the linings of industrial kilns such as ladles.

In such cases, if a neutral or basic refractory is used, wear due to slag will be significantly improved, but since neutral or basic refractories have high thermal conductivity, the temperature of the molten steel received will be low. In addition, neutral or basic refractories have a higher specific gravity than acidic refractories, which increases the weight of the entire kiln. The disadvantage of refractories is that they are more expensive than acidic refractories.
On the other hand, the furnace walls of industrial furnaces suffer local wear and tear due to chemical attack by molten steel, slag, etc., mechanical wear, spalling, etc., and this wear progresses.

In such a case, by spraying and repairing the worn parts, the worn parts are equalized and the condition is made uniform including the non-worn parts, thereby extending the life of the entire kiln. Even in the case of furnaces lined with acidic refractories, the above-mentioned spray repair has been carried out for some time.
The spraying materials used in this case include acid sprayed refractories made of waxite and the like, and basic sprayed refractories made of magnesia, dolomite, and the like.

However, the former acidic sprayed refractory has poor corrosion resistance and abrasion resistance, and the latter basic sprayed refractory has excellent corrosion and abrasion resistance, but the acidic refractory that makes up the lining Because of their different chemical and physical properties, when used for spray repair, the phenomenon of flaking often occurred early after repair. This flaking phenomenon of the basic sprayed refractory is caused by the difference in expansion with the acidic refractory composing the lining and the reaction between the acidic refractory lining and the basic sprayed refractory, resulting in the formation of orthosilicate groups, Sagiri ρ, SiO2, M is a metasilicate
gO-SiO.

MgO-Si0, etc. This is thought to be due to a drain phenomenon in which a glass phase is formed with a system compound and absorbed by the basic sprayed refractory. For this reason, conventional technical means have attempted to solve the above-mentioned problems when using basic spray refractories for repair by focusing on their additives and binders, but the type of aggregate has not been changed. However, chemical treatments based on additives and binders alone have their own limitations, and the problem has not yet been solved.

The present invention was developed in consideration of the current situation, and solves the above-mentioned problems that occur when using basic sprayed refractories for spraying repair of linings made of acidic refractories, rather than from the viewpoint of the material of the sprayed material. , a method of solving the problem by spraying means,
We propose a repair method that does not require complicated aggregate specifications or binder selection.

Specifically, a neutral sprayed refractory is sprayed on the worn parts of the lining made of acidic refractory to form a base, and a basic sprayed refractory is sprayed on top of that to effectively repair the lining as desired. The ultimate purpose is to provide a method to obtain The present invention will be described in detail below. Specific materials for the neutral spray refractory used in the present invention include alumina, high alumina, alumina-chromium, chromium, spinel, and carbon. These neutral refractories may be used alone or in combination of two or more types.

In addition, as long as the properties of the neutral spray refractory are not impaired,
Even if the above neutral refractories are mixed with basic refractories, acidic refractories, or both, the acidic refractories that basically constitute the lining or the basic sprayed refractories that form the repaired surface. This is thought to equalize the expansion rate of sprayed refractories that are bonded to each other when there is a significant deviation in the gradient of hydrogen ion concentration. It has been confirmed through many experiments that the limit for contamination should be 30% or less. Specific examples of the material of the basic sprayed refractory include magnesia, magnesia dolomite, and magnesia-chromium.

All of these sprayed refractories are configured in particle size and the additives and binder are adjusted using known methods.

The spraying machines used for spraying repairs can be roughly divided into wet type and dry type. Although it is possible to use a dry method, a dry method is preferred because it is easy to handle. In the actual construction of the method of the present invention, neutral spraying is first applied to the worn parts of the acidic refractory 2 forming the lining layer 1 using the above-mentioned sprayed refractory and spraying machine. The refractory 3 is sprayed to form a base, and then the basic sprayed refractory 4 is sprayed on top of it, and in this case, the first spraying is the neutral spraying refractory, and the second spraying is the neutral spraying refractory. Each spray with the basic spray refractory may be carried out by loading each into a separate spray machine, or the amount of each subsequent spray may be pre-weighed and placed in the material tank of one spray machine. Load it again,
The neutral sprayed refractory may be sprayed first, and then the basic sprayed refractory may be sprayed out of the tank in this order.

In this way, the acidic refractory lining repaired by the method of the present invention is sprayed with the basic sprayed refractory with the neutral sprayed refractory interposed as an intermediate layer. The expansion difference with the refractory is alleviated by the neutral sprayed refractory, which exhibits an intermediate coefficient of expansion between the two.

Furthermore, this neutral sprayed refractory has low reactivity with both the acidic and basic sprayed refractories that are in contact with it on both sides, so it is less susceptible to glass formation that occurs in conventional spraying methods that do not include a base that has a mitigating effect. Therefore, the basic sprayed refractory can fully exhibit its own corrosion resistance and wear resistance without peeling off from the sprayed area. Next, the results obtained for one example of implementing the method of the present invention will be shown in comparison with those obtained by a conventional method. The lining was piled up on the wall and heated to 1,200°C to serve as a virtual model of the area to be repaired on the lining.

The neutral spray refractories of Examples had the following compositions.

Similarly, the basic sprayed refractory had the following composition.

'~ノJ \N~WJ7'RJ)I7J~)〃Hノ
1υ 1U\'' The spraying machine is a dry type, and the neutral sprayed refractory is applied to the surface of the model in advance.
0? Spray to a thickness of 3077!77! Sprayed to a thickness of .

The comparative example was carried out by a conventional method, in which the same basic sprayed refractory was directly sprayed onto the waxite lining under the same conditions as the above-described examples.

Comparing the construction conditions and the condition after spraying repair, both the working example and the comparative example showed good adhesion during spraying, but the results of observing the condition of the sprayed refractory after the furnace was cooled showed that the comparative example (existing In the case of the previous method), a part of the refractory material had flaked off, and even in the case where the flaking had not yet occurred, warping was observed between the lining and the sprayed refractory layer, and it was found that the sprayed refractory layer could be easily refracted even if a slight impact was applied. It was in a state of peeling.

On the other hand, in the examples produced by the method of the present invention, neither peeling nor warping was observed, and the original lining component and the sprayed refractory formed a strong integrated structure. As mentioned above, the method of the present invention is suitable for spray repair of acidic refractory linings without the need for complex material selection or aggregate specifications, using only conventional refractories, additives, and binders, and using basic spray repairs. This change is based on this philosophy, making it possible to prevent the flaking of refractories, fully demonstrating the corrosion resistance and abrasion resistance of basic sprayed refractories, and significantly improving the spraying repair effect. It goes without saying that these applications are included in the technical idea of the present invention.

[Brief explanation of the drawing]

The drawing shows a cross section of a main part of an industrial kiln whose lining has been repaired by spraying according to the method of the present invention. 1... Lining, 2... Acidic refractory, 3... Neutral sprayed refractory, 4... Basic sprayed refractory.

Claims (1)

[Claims] 1. Spraying repair of an industrial kiln characterized by spraying a neutral sprayed refractory onto damaged areas of the lining made of acidic refractory to form a base relaxation layer, and then spraying a basic sprayed refractory on top of that. Method.