JPS63156078A - Spray mending material for metal refining furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The invention relates to a spray repair material for metal smelting furnaces.

Conventional technology and its problems In recent years, highly durable magnesia-carbon bricks have come to be used as lining materials in metal smelting furnaces such as converters, and repair of local melting damage such as in slag lines has become more and more important. It has come to have a great influence on the life of the furnace. Conventional local dissolution 4
When repairing areas, spraying repair methods are mainly used. This is a mixture (
This is a method in which spraying material) is mixed with water at the tip of a spray nozzle and sprayed onto the furnace wall to form a repair layer. Conventional spraying materials include basic refractory raw materials such as magnesia, dolomite, and magnesiat (comite (hereinafter referred to as "Magdro")), phosphorus W, etc., with emphasis on workability during spraying, especially adhesion to furnace walls.
! A highly viscous and fast-curing material containing a binder such as i-salt and a phosphate curing agent such as ultrafine magnesia powder or a lime compound has been mainly used. However, 1) these repair materials have insufficient durability and hot strength;
) Due to recent changes in operating conditions, the erosion of steeply sloped parts such as trunnions has disappeared, and only gently sloped parts such as slag lines are now melted. Repair materials are now in demand. This is because low-viscosity and slow-curing repair materials boil when applied hot, so filling and drying proceed simultaneously, making the construction body dense and reducing its durability and strength. This is because it has the advantage of improving performance. Therefore, in order to obtain a slow-curing repair material, conventional repair materials that do not contain a phosphate curing agent are used, but these are undesirable due to the following drawbacks. That is, when a dolomite-containing raw material such as dolomite or magdromite is used, calcia eluted from the dolomite raw material during the boiling period of the material reacts with sodium phosphate, which is a binder, to form a water-insoluble polymeric phosphate. This causes the problem that the hardening process becomes faster. On the other hand, magnesia raw materials have poor reactivity with sodium phosphate, but they also lack durability, especially volumetric stability under hot conditions, and are prone to structural spalling due to large slag penetration. It has disadvantages that are inferior to the material.

Means for Solving the Problems In view of the above-mentioned problems of the prior art, the inventor of the present invention has conducted extensive research and found that even if Magdro raw material is used as a refractory aggregate, a strong material that does not contain condensed phosphoric acid and phosphorus. By using an electrolyte with an alkali salt and adding calcium phosphate, which is poorly water-soluble, to prevent the hot strength of the sprayed material from decreasing due to the alkali content, it has slow curing properties and has long-lasting properties such as corrosion resistance. We discovered that it is possible to obtain a spray repair material for metal smelting furnaces that exhibits strong elasticity and strong adhesion to the furnace wall.
The invention has been completed.

That is, the present invention provides a refractory raw material 100 consisting of 30 to 70% by weight of dolomite raw material and 70 to 30% by weight of magnesia raw material.
2.5 to 7.0 thousand G parts of heavy convex single condensed sodium phosphate,
The present invention relates to a spray repair material for metal smelting furnaces containing 0.2 to 1.5 parts by weight of a strong electrolyte alkali salt and 0.3 to 1.5 parts by weight of poorly soluble calci phosphate shim.

In the present invention, dolomite raw materials and magnesia raw materials are used as refractory raw materials.

As the dolomite raw material, any material commonly used in this field can be used, but it usually contains 40% or more of calcia,
Use one with a bulk specific gravity of 3.20 or more. However, in consideration of the volume stability of the material, the ability to prevent slag penetration, etc., it is particularly preferable that the calcia content be 55% or more. The content of the dolomite raw material is preferably about 30 to 70% by weight of the total amount of the refractory raw material. If it is less than 30% by weight, the effect of calcia is hardly exhibited, while if it exceeds 70% by weight, dolomite fine powder cannot be used due to dusting, and the particle size structure is restricted, resulting in poor spray workability. Corrosion resistance etc. decrease.

As the magnesia raw material, those commonly used in this field such as seawater magnesia, electrofused magnesia, and natural magnesia can be used, but the magnesia content is usually 92%, the SiO2 content is 5% or less, and CaO/S i 02 = 0.3 or more. I'll use that one.

The particle size of the refractory raw material is not particularly limited and may be selected as appropriate, but usually coarse particles with a particle size of about 5 to 1M are used, about 30 to 50 kg,
Intermediate particles with a particle size of 1aI or less are about 20 to 40 weight and 0.0
It may be used so that it contains about 20 to 40 weight of fine powder of 74 m or less. However, in consideration of material dusting, it is preferable not to use dolomite fine powder with a particle size of 0.074 weight or less.

In the present invention, curing of the repair material is delayed by using condensed sodium phosphate and an alkaline salt of a strong electrolyte that does not contain phosphorus. This method takes advantage of salting-out dyeing, in which the dissolution of two strong electrolyte salts in water is affected by the concentration of each other, and is usually lower than when they are used alone. The reaction, that is, the Na ions of the water-soluble sodium phosphate are replaced with the Ca ions in the material to form a water-insoluble polymer phosphate, is delayed.

Any conventional condensed sodium phosphate can be used, and examples thereof include sodium birophosphate, sodium tripolyphosphate, sodium tetrapolyphosphate, and sodium hexametaphosphate. The blending amount is preferably about 2.5 to 7.0 parts by weight per 100 parts by weight of the refractory raw material. If the overlap is less than 2.5 parts, sufficient adhesive strength will not be developed in the initial stage of use, while if it exceeds 7.0 parts, flux seedlings in the material will increase and corrosion resistance will decrease.

As the alkaline salt of a strong electrolyte that does not contain phosphorus, any weakly acidic to weakly basic sodium salt or potassium salt having a solubility of 10 or more can be used, such as Nac:,
91KC (1st grade chloride, Na2CO3, K2 CO3
and acetates such as CH3COONa. Its blending amount is 0 per 100 weight of refractory raw materials.
．． The amount is preferably about 2 to 1.5 parts by weight.

If the amount is less than 0.2 parts, the curing retardation effect is poor;
．． If it exceeds 5 parts by weight, the amount of dissolved phosphate will decrease, making it difficult to develop strength after drying, and CQ1CO2
Since it contains components that decompose during heating, problems such as explosion during heating and a decrease in corrosion resistance occur.

As the poorly water-soluble calcium phosphate, any of the usual ones can be used, such as dibasic calcium phosphate, dibasic calcium phosphate, calcium pyrophosphate, and the like. The mixing ratio m is preferably about 0.3 to 1.5 parts per 100,000 m parts of the refractory raw material. 0.3 layer B
If it is less than 1.5 parts, the effect of improving hot strength will be small, while if it exceeds 1.5 parts, the effect will not change much and it will be uneconomical.

The repair material of the present invention is prepared by adding a predetermined convexity of each of the above raw materials according to a conventional method.
For example, it is manufactured by mixing with an Eirich mixer or the like.

When repairing a damaged area using the repair material of the present invention, any spray repair method used in this field can be employed.

Effects of the Invention The spray repair material for metal smelting furnaces of the present invention has extremely excellent corrosion resistance and adhesive strength to the furnace wall, and exhibits extremely high durability.

EXAMPLES Examples and comparative examples are given below to make the present invention even clearer.

Examples 1 to 5 and Comparative Example 1.2 To 1 part of 100 fiei of refractory raw materials, each raw material was added in the proportions (parts by weight) shown in Table 1, mixed with an Eirich mixer, and the repair material of the present invention and the conventional repair material were mixed. manufactured the material. The dolomite raw material is natural dolomite with a calcia content of 58% and a bulk specific gravity of 3.25, and the magnesia raw material is seawater magnesia with a magnesia content of 94%, a 3i02 content of 2.5%, and CaO/S i 02 = 0.4. of,
In addition, as condensed phosphoric acid, Na2O content 123%, P
Sodium tetrapolyphosphate containing 63% 2O5 was used.

After kneading the obtained repair material with water, it was poured into a brick frame heated to 1200°C in an oxygen-propane furnace, and its hardening properties were determined, and a construction sample was prepared for the quality test described later. . The dimensions of the sample are 170x300
x60m, 170x300#lj+ side is brick frame paving brick (dolomite, 250x350x110Im
). A slag coating was applied to the surface of the paving line tile in advance, so that the construction work (repair layer) and the paving brick were bonded through the slab surface. The compactness and corrosion resistance of the constructed samples were examined.

For the compactness test, 1llt was used for J15R-2205.
1. , porosity and bulk specific gravity were measured. For the corrosion resistance test, from the construction sample, the outer dimensions were 50 m in diameter x 50 m in height,
A crucible-shaped sample with a concave diameter of 20#llI x height of 20Jl#I was cut out, this sample was filled with 30g of converter slag, and then heated at 1700°C in an oxygen-propane furnace.
After firing for 3 hours, the crucible-shaped sample was cut in the longitudinal direction, and the area eroded by the slag and the area permeated by the slag were measured. The adhesive strength is 40mm, which is the size of the paving brick and the construction body.
Cut out a sample of X40X120 shoes, JISR-221
3, a room temperature bending strength test was conducted centering around the adhesive interface to measure the strength. The results are shown in Table 1.

From Table 1, it can be seen that the repair material of the present invention has a faster curing time, better density, corrosion resistance, adhesive strength, etc. than conventional repair materials.

(that's all)

Claims (1)

[Claims] 1. 100 parts by weight of a refractory raw material consisting of 30 to 70% by weight of dolomite raw material and 70 to 30% by weight of magnesia raw material, 2.5 to 7.0 parts by weight of condensed sodium phosphate, and 0.0 parts by weight of a strong electrolyte alkaline salt that does not contain phosphorus. A spray repair material for a metal smelting furnace containing 2 to 1.5 parts by weight and 0.3 to 1.5 parts by weight of hardly soluble calcium phosphate.