JPS6370091A - Spray repairing method of molten steel treater - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for repairing damaged lining refractories of immersion pipes and lower tanks in steelmaking furnaces such as converters and RH vacuum degassing equipment. This invention relates to a method of repairing a damaged refractory layer by spraying a refractory material for repair.

[Conventional technology]

For example, R) (When repairing the immersion tube of a vacuum degassing device such as a furnace, punching was performed manually. However, this manual repair work was inefficient and the work environment was poor. Due to the high-temperature atmosphere, workers tended to avoid using it.Therefore, online repair (hot work) was used.

With the aim of improving the working environment and speeding up labor-saving work in the industry, automatic spraying has begun to shift from spraying using machines to repair. Along with this, it has become possible to repair the inner walls of immersion pipes, which previously could not be repaired with punching materials.

However, when using conventional spraying materials,
Since the spraying temperature on the inner wall of the riser pipe was as cold as 600 to 800°C, the adhesion rate was low, and even if it did adhere, the repaired body would be inferior in terms of adhesive strength and structure. When the riser pipe repaired in this way was incorporated into a vacuum degassing device and used, it was subjected to abrasion effects by the molten steel flow, and could not withstand long-term use.

Therefore, in JP-A No. 54-69113, a spraying material is proposed in which a fire-resistant aggregate is coated with a resin having a softening point of 200°C or less, and JP-A No. 49-69113
No. 5409 proposes a refractory composition using used bricks containing amorphous carbon.

[Problem that the invention seeks to solve]

However, the spraying method disclosed in JP-A No. 54-69113 cannot completely eliminate fumes during work when using repair materials, and repairs cannot be performed in a good working environment. In addition, this spraying has the disadvantage that boiling may sometimes occur in repair materials because the removal of volatile matter is insufficient.

On the other hand, in the fire-resistant composition disclosed in JP-A-49-35409, when a powder binder is used, the adhesive strength during hot spraying is not sufficient and contributes to improved durability. It was difficult to fully demonstrate the effect of carbon addition.

The present invention is intended to eliminate various defects in the conventional spraying method and materials, and particularly to repair the refractory linings applied to molten steel processing equipment such as immersion pipes and lower tanks of RH furnaces. The purpose of this method is to form a repair refractory material layer with excellent adhesion rate, adhesive strength, fire resistance, etc.

[Means for solving problems]

Is the spraying repair method of the present invention adjusted in particle size to achieve its purpose? A refractory aggregate consisting of 3 to 60 IgO materials is prepared, and 0.1 to 2 parts by weight of a hardening accelerator is mixed with 100 parts by weight of the refractory aggregate to form a powder for spraying. Add 0.5 to 3 parts of a wetting agent to the powder and prepare the pre-kneaded fireproof spraying material.
A sodium silicate solution having a viscosity of 8 cP and containing 4 to 6% by weight of NazO and 17 to 20% by weight of 5ift is applied to the front of the nozzle at a rate of 18 to 25 parts by weight per 100 parts by weight of the fireproofing material. It is characterized by spraying while mixing in the injection section.

The present invention will be explained in detail below.

In the spraying repair method of the present invention, spraying containing a curing accelerator involves pre-wetting the powder with water or a non-aqueous solvent;
This is fed from the gun tank to the nozzle. On the other hand, a sodium silicate solution having a specific composition is used as a binder, and is sprayed while being added to and mixed with the powder before the nozzle opening.

In the powder spraying used at this time, the ratio of MgO-C coarse angle to the total aggregate is 40 to 1%. This MgO--C rough square has volatile matter removed by heat treatment, and does not generate smoke during or after spraying. Therefore, repair work becomes easier.

In order to fully exhibit the effect of this MgO--C rough angle, if it is less than 4094, it will not be effective, and if it is more than 70%, problems such as carbon pickup will occur.

The hardening accelerator added to this refractory aggregate is an inorganic acid, which is well known as a hardening agent for sodium silicate. Organic acids, Ca, Mg, N, Ba. Among polyvalent metal compounds such as Zr, alkali metal carbonates, alkali metal phosphates, fluorides, and cements, examples include aluminum phosphate, oxalic acid, citric acid, tartaric acid, malic acid, P-)luenesulfonic acid, quicklime, and slaked lime. , magnesium oxide, aluminum chloride, calcium chloride, calcium nitrate, hydrogen carbonate 1
Sodium, sodium hexametaphosphate, sodium silicofluoride,
Examples include ammonium fluoride and calcium aluminate.

In addition, the sodium silicate solution used is 6 to 8 cP at 15°C.
It has a viscosity of That is, as shown in Figure 1, those with low viscosity in the shaded area are used. This sodium silicate solution contains 4 to 6 parts by weight of NagO and 5 in1
It has a composition of 17 to 20 parts by weight.

The optimal amount of the sodium silicate solution binder added to the pre-kneaded fireproof spray material is 18 to 25 parts by weight, whereby the adhesion rate can be maintained at 80% or more.

By mixing this sodium silicate solution with the powder at the injection part in front of the nozzle part, the spraying process takes advantage of its quick hardening properties.

[Effect]

In this way, fireproof spraying sprays the material onto damaged lining refractories of molten steel processing equipment, and when repairing the work, the refractory material is evenly applied to the construction material with an extremely high adhesion rate and without producing smoke. is obtained. Moreover, this constructed body can sufficiently withstand the steam pressure generated inside the constructed body.

That is, in the present invention, Mg is used as one component of the aggregate.
Since O-C rough angle is used, MgO-based spraying has improved slag digestion resistance (corrosion resistance) and volume stability compared to materials, and also shows excellent performance against ablation caused by molten steel flow. , this MgO-C rough square has an MgO content of 8~
99 coating, or coating by mixing flaky graphite with resin or phenol, or pitch.

Coated with a mixture of flaky graphite and resin or phenol, etc., subjected to impregnation treatment (baking) at a temperature of 300°C or higher, and then crushed, or used MgO-C manufactured through these treatments. The crushed bricks are used directly as rough squares.

In addition, by mixing a sodium silicate solution with the fireproof spraying material containing a hardening accelerator at the injection point in front of the nozzle, it effectively functions as a binder. That is,
This sodium silicate solution was mixed with the spray powder from the beginning and then fed from the gun tank to the spray nozzle.
A curing reaction occurs in the gun tank, along the feeding route, or inside the nozzle during spraying, causing blockage, and powder cannot be fed smoothly during spraying. In addition, the spraying may be done by adding a sodium silicate solution to the powder after it has been ejected from the nozzle.
Since the powder and the sodium silicate solution are not sufficiently mixed during spraying, the desired curing reaction cannot be expected. On the other hand, when the sodium silicate solution is mixed with the powder by spraying it at the injection port in front of the nozzle, the clogging described above does not occur and a sufficient curing reaction can be obtained. For this reason, fireproof spraying materials are sprayed onto the target areas with a high adhesion rate. The repair fireproof material layer produced by spraying also has excellent strength due to its density.

The second line shows the effect that this sodium silicate solution has on the adhesion rate of fireproof sprayed materials. As is clear from this figure, 18
It can be seen that a high adhesion rate can be obtained when sodium silicate is added in a range of 25% by weight.

Moreover, FIG. 3 shows the influence of the sodium silicate solution on the porosity of the repaired refractory material layer formed thereon. That is, when a sodium silicate solution is mixed into fireproof spraying materials within the scope of the present invention,
A repaired refractory layer with low porosity has been obtained.

〔Example〕

Hereinafter, the effects of the present invention will be specifically explained with reference to Examples. Table 1 shows the properties of the sprayed materials of various compositions and the resulting repaired refractory layers.

Table 1 Note: The corrosion resistance test was conducted using a synthetic slag of CaO/5iOz=2.0 by a rotary erosion method in which the slag was brought into contact with the slag 5 times in 30 minutes at 1600°C. As a result, those exhibiting the best corrosion resistance were expressed as 01, which were expressed as ○, those with slightly poor corrosion resistance were expressed as △, and those with poor corrosion resistance were expressed as x.

As is clear from Table 1, in the case of Comparative Examples 1 and 3 in which MgO-C rough angle was not used, slag infiltrated into the obtained repaired refractory material layer to a large extent, and therefore the melting loss also increased.

Also, Comparative Example 3 in which spraying was performed using a solution binder.
And in the case of Examples, the adhesion rate was significantly improved when sprayed at 700°C.

According to the embodiment of the present invention, M
Since the gO-C rough edges are covered with a binder and act as an oxidation inhibitor, the oxidation of carbon can be delayed. Therefore, the obtained repaired refractory material layer has particularly excellent slag infiltration resistance and improved erosion resistance.

Looking at the effect of the MgO-C rough angle, as is clear from the comparison between the example and comparative example 4, in the case of the example, the survival rate was 30 to 30 in the actual furnace test as the inner wall of the riser pipe.
It was confirmed that it could be used three times until it reached 50%.

〔Effect of the invention〕

As explained above, since the spraying repair method of the present invention uses fireproof aggregate containing MgO-C,
It is possible to form a repaired refractory material layer that does not generate smoke during construction and has excellent slag infiltration resistance, volume stability, abrasion resistance, etc. In addition, since a sodium silicate solution as a binder is mixed into the fireproof spraying material before the nozzle part, a good mixing state can be obtained without clogging the feeding path. Therefore, the curing reaction of sodium silicate can be effectively used, and fireproofing can be sprayed onto the target area with a high adhesion rate.

[Brief explanation of the drawing]

Figure 1 shows the sodium silicate solution used in the present invention. FIGS. 2 and 3 are diagrams showing the viscosity range of the liquid binder, and are diagrams showing the influence of the spraying amount of the sodium silicate solution binder on the properties of the material.

Claims (1)

[Claims] 1. 30-60% by weight of MgO material whose particle size is adjusted and M
gO-C rough corner (F.C10-20%) 40-70% by weight
A refractory aggregate consisting of:
By blending 2 parts by weight, a sprayed powder is obtained, and 0.5 to 3 parts by weight of a wetting agent is added to this sprayed powder.
When preparing the pre-kneaded fireproof spraying material and performing the construction of this fireproof spraying material, it has a viscosity of 6 to 8 cP at 15°C, and contains Na_2O_4 to 6% by weight and SiO_2.
Molten steel treatment characterized by spraying a sodium silicate solution containing 17 to 20% by weight at a ratio of 18 to 25 parts by weight to 100 parts by weight of the fireproof spraying material while mixing in an injection part in front of the nozzle part. How to repair equipment by spraying.