JPS5973475A - Manufacture of flame spray powder material - 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 The present invention relates to a method for producing a thermal spraying material used in flame spraying using gas fuel or liquid fuel such as kerosene or light oil and oxygen.

Recently, the melting temperature of steel in steelmaking furnaces such as converters has become significantly higher due to the upgrading of steel, and conventional semi-dry spraying materials using water do not have sufficient durability. It's becoming harder to get it. Furthermore, since the semi-dry spraying method contains water during spraying, it unnecessarily supercools the bricks, giving them thermal shock and promoting flaking damage to the bricks. For this reason, flame spraying, a completely dry hot repair method that replaces semi-dry spraying, has been studied and is beginning to be put into practical use. The following methods are being considered for this flame spraying. i.e. /) Combustion of solid fuel with oxygen to form a flame.
2) Combustion of gaseous fuel with oxygen to form a flame,
J) There are three methods of flame formation, including burning liquid fuel with oxygen to form a flame, in which the spray material is retained and melted to adhere to the furnace wall.

It is thought that flame spraying produces a denser workpiece than the ``conventional'' semi-dry spraying method, has much higher adhesive strength, and has significantly improved durability. These thermal spray materials are made by mixing additives with refractory materials or by firing and crushing them. That is, , 2) Mix 700 parts by weight of refractory material with 70 to 30 parts by weight of smelting furnace slag and 10 to 40 parts by weight of carbonaceous solid fuel (from 1977, Koku Ki, ?) MgO clinker - 3 or more Converter or blast furnace slag 9! less than 1
7 mixed firing at a temperature of 00°C or higher (Tokukosho!rg-, 23tpzR).

&) Adding a small amount of additives to MgO clinker (iron and copper: VoLAf No, /l S-1,t!r(/
912) ,) As mentioned above, there are various methods of manufacturing thermal spray materials.

The above 1) and 2) are thermal spray materials made by mixing a carbonaceous solid fuel such as coke with a refractory material or/and smelter slag, but this has a low adhesion rate.The reason for this is the melting point of the refractory material. It is difficult to obtain a high melt viscosity necessary for adhesion, and although the low-melting additive melts sufficiently, the low-melting additive and the fire-resistant additive fly separately, so the fire-resistant material tends to rebound. 3) is a material used in flame spraying with acetylene-oxygen.

Although this method has a better adhesion rate than simply mixing refractory material and slag, it has the following drawbacks.

In other words, since the slag is used once it has cooled, the process of mixing the slag with the crushed refractory material, firing it, and then re-pulverizing it is very complicated, and a lot of thermal energy is required to manufacture this sprayed material. There are drawbacks to spending. Also, although it is said that firing is performed at a temperature of 100°C or higher, if the temperature is lower than 200°C, the MgO surface cannot be covered with slag due to the reaction between MgO and slag, so the MgO deposition rate cannot be satisfied. 1) is a flame spraying material using kerosene and oxygen.Although a dense and high sprayed film can be obtained with a small amount of additives, the adhesion rate is extremely low, making it unsuitable for practical use.

The present invention relates to a method for producing a thermal spray material which is highly efficient and has excellent adhesion. Molten slag discharged from the steelmaking process of converters, electric furnaces, ladles, blast furnaces, pig iron mixers, etc. is allowed to flow down, and refractory material is sprayed at high speed from the side, front, or back of the flowing slag to form the surface of the refractory material. This is a manufacturing method that creates a thermal spray material with good adhesion by coating the surface with molten slag.

As mentioned above, the molten slag used in the present invention can be basic, neutral, or acidic slag from converters, electric furnaces, ladles, blast furnaces, pig iron mixers, etc. The viscosity of the molten slag is also related to the slag composition and the temperature in the molten state, and it is desirable that the molten slag is in a state where the molten viscosity is as low as possible between θθ and /θ centipoise. This is because the lower the molten slag viscosity, the easier it is to coat the refractory material.

The refractory materials used at this time are basic refractory materials such as magnesia, maguro, chromite, dolomite, spinel, etc.
Neutral and acidic refractory materials such as AJ-203, Sin, mullite, chamotte and 810, Si, N4, graphite,
It is possible to use a refractory material made of one or more non-oxide materials such as coke. Particle size is important for refractory materials sprayed onto molten slag. It is preferable that the particle size of the spraying material is mainly 3 to 1 oooμ.

If the amount is less than 5μ, it is undesirable because it will scatter during thermal spraying and the processing efficiency will be significantly reduced.If it is more than 7000μ, the slag coating will be easy, but when the slag-coated refractory material is thermally sprayed, there will be a lot of rebound, which is undesirable. In the method for producing a powder material for thermal spraying of the present invention, the amount of slag coating on the refractory material varies depending on the type of slag, the melt viscosity of the slag, the amount of slag flow, the blowing speed of the refractory material, the particle size, etc. 70~ for the total amount of slag? □Weight weight is desirable゛. If the content is less than 10% by weight, the refractory material cannot be sufficiently coated with slag, and the adhesion rate during thermal spraying becomes low, which is not preferable. Further, if the amount of slag coating is 90% by weight or more, corrosion resistance will be significantly deteriorated when used in a steel making furnace, etc., which is not preferable. It is also effective to preheat the refractory material to about 6θθ°C to 200°C in order to improve the efficiency of slag coating on the refractory material. Next, the present invention will be described in detail with reference to examples.

Example/.

, converter furnace slag in a molten state at a rate of 200 centimeters per minute
Two K MgO clinker 10θθμ sandy soils allowed to fall naturally at a rate of 00kl - 7-0chi, lθθθ~10μ
90 inch to 100 per minute 9, blowing speed trom
/second, resulting in an average slag coverage of 50
% by weight of thermal spray powder material could be produced. When the powder material for thermal spraying was thermally sprayed by oxygen-propane flame spraying, a deposition rate of 9° was obtained. The adhesion rate of thermal spray material made by mixing conventional converter slack powder and MgO powder is 1.0.
It was found that the adhesion rate was significantly improved, with a low adhesion rate of % to OtS.

In addition, with the conventional thermal spray material that is a mixture of converter slag powder and MgO powder, MgO powder of 300μ or more does not adhere.
Although there was a drawback that rebound occurred, the present invention was able to improve this point as well.

Example.

Desulfurization slag made of molten soda ash with 3θ centibodies is allowed to fall naturally at a rate of 1 sokg per minute, and Mg
O-talinker and dolomite clinker: /(IO'00p b% in D mixed elJ, 1000-5μgzi
, 10 inches below sμ was preheated at 100° C., and O- was blown in every minute at a rate of 0.0 m/fF). As a result, a powder material for thermal spraying with a slag coating amount of 10 layers was produced.

This powder material for thermal spraying was sprayed using oxygen kerosene flame spraying in the same manner as in Example 1. ! A high adhesion rate of 1% was obtained.

Example 3 Molten blast furnace slag of 10θ centipoise is produced per minute.
Let it fall naturally with OKG, and 100 ~! When mullite grains of μm were sprayed at a blowing speed of 70 m/min, a thermal spray material with a sufficient slag coating was produced. This slag covering amount is g! % by weight. Where was this thermal spray material sprayed using the oxygen-propane method? An adhesion rate of 3 was obtained.

As described above, a powder material for thermal spraying coated with slag and having a good adhesion rate was produced by blowing a refractory material into the place where various types of molten slag were allowed to flow down.

Patent applicant: Nippon Kokan Co., Ltd. The same old book + at Shishiki Company Same 11th Jirengho-style company My way of understanding:l

Claims (1)

[Claims] A method for producing a thermal spray material for slag coating obtained by spraying a refractory material onto flowing slag.