JPS6112968B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims at refining molten metal by adding oxygen, nitrogen, argon, chlorine, carbon tetrachloride, or a mixture thereof to the molten metal, or a mixture of these gases and a solid scouring agent. This relates to a lance pipe for blowing.

Conventionally, in order to reduce wear and tear on lance pipes made of steel pipes for blowing gas or a mixture of gas and solids into molten metal in melting furnaces, ladles, pig iron trucks, tundishes, or holding furnaces,
Steel pipes with refractory coating applied to the outer periphery or inner surface have been developed, and metal fibers are mixed into steel pipes or steel pipes with oxidation-resistant coating to strengthen mechanical strength and thermal shock resistance. (Japanese Patent Application Laid-Open No. 51-2606), and metal pipes whose inner and outer surfaces are coated with a mixture of fireclay and brick powder and a mixture of fireclay and coke powder in one or two layers (Japanese Patent Laid-Open No. 51-3304) ), which is characterized by the installation of a tip protector, and which covers the other steel pipe parts with hollow molded refractories (Utility Model No. 51-117807). A type in which a support metal is attached and a monolithic refractory is coated (Utility Model No. 52-80001), a cylindrical stainless steel mesh is embedded in a refractory covering the outer periphery of the steel pipe. (Japanese Unexamined Patent Publication No. 50-128615) A steel pipe wrapped with a laminated fire-resistant reinforcing material made of asbestos paper, aluminum foil, glass cloth, etc. (Utility Model Publication No. 51-1286), the outer periphery of a steel pipe or a steel pipe treated with aluminum diffusion and penetration treatment. Asbestos string, rope, and cotton rope are wound at appropriate pitches, and a mixture of 30 to 200 mesh of powdered granular refractory, fireclay, and alkali silicate is applied on top.
Refractory-coated steel pipes (Special Publication No. 48-27045)
There are many examples, each of which has achieved success.

However, these have problems such as insufficient thermal shock resistance of the refractory coating layer, excessive weight to compensate for this, and peeling of the coated refractory during use due to vaporization of excessive ignition loss components. The current situation is that Japan is not immune to its shortcomings.

The present invention has overcome these drawbacks; it is lightweight, has excellent thermal shock resistance, has little loss on ignition, has excellent slag resistance, and has excellent corrosion resistance against molten metals such as hot metal, molten steel, aluminum, and aluminum alloys.
In addition, it can withstand the shocking repeated stress caused by the intense vibrations that occur when blowing gas into molten metal.
This provides a lance pipe that can be used repeatedly.

That is, in the lance pipe of the present invention, the refractory material to be coated on the outer periphery of the steel or ceramic pipe is composed of refractory fiber thread, string, tape, or cloth, powdery refractory aggregate, and refractory binder. These three types of materials interact with each other to obtain the above-mentioned excellent properties. In other words, the refractory aggregate compensates for the lack of fire resistance and slag resistance in the refractory fiber or its combination with the refractory binder, and the combination of the refractory aggregate and the refractory binder has improved thermal shock resistance and thermal insulation. Fire-resistant fiber thread, string, tape or cloth compensates for the lack of
It forms a strong heat insulating layer with high fire resistance, making steel pipes withstand use with molten metal at temperatures above their melting temperature, and ceramic pipes mitigating thermal shock. It can withstand sudden immersion in molten metal.

The refractory aggregate used in the present invention is alumina, silica, titania, zirconia, silicon carbide, boron carbide, silicon nitride, boron nitride, or alumina, silica, magnesia, chromia, ittria, calcia, lithia, titania, zirconia,
One or more natural or synthetic crystalline or amorphous substances containing hafnia, lanthanide element oxide as a main component, particle size of -10 mesh, -200 mesh and 48 to 200 mesh at 15 weight When using an acidic and stable refractory binder, alumina sol can be used as the refractory aggregate with a particle size of -200 mesh. Similarly, the fire-resistant binder is made of fire-resistant clay using silica sol, hydrolyzed ethyl silicate, and water as a dispersion medium, and the residue obtained when the dispersion medium is completely evaporated and scorched at a temperature of 1100K or higher, that is, the residue when scorched is Solid content 5-40
Those containing % by weight are suitable. Therefore, in the case of fireclay, it can be replaced with -200 mesh of fire-resistant aggregate, and the mixing ratio of both is 50 mesh of fire-resistant aggregate.
~90% by weight, the remainder being a refractory binder containing a dispersion medium. In addition, fire-resistant fiber threads, strings, tapes or cloths include fibers whose main components are silica and alumina, fibers whose main components are silica and alumina and which contain chromia as an active ingredient, silica fibers, alumina fibers, boron nitride fibers, Made of a blend of one or more of zirconia fibers, silicon carbide fibers, boron carbide fibers, carbon fibers, or graphite fibers, with a diameter or thickness of 0.5 to 15 mm in the natural state,
In order to prevent cutting during coating construction, organic fibers or metal wires may be mixed in to supplement the tensile strength.The fabric may be woven or felt, and if multiple layers are formed, each layer may be Different types or different forms may be used. Therefore, the particle size distribution of the refractory aggregate is a requirement for providing the above-mentioned synergistic effect due to the combination of the three types of materials, and due to the presence of the above-mentioned refractory binder, most of the -200 mesh particle size is It is attached to the single fibers that make up fire-resistant fiber threads, strings, tapes, or cloth, and coarser particles are attached to fill the gaps, and the surplus contains fine particles to form an outer layer to achieve its purpose. It is meant to encourage people. Particles coarser than 48 mesh are effective in reinforcing the layer covering the outer surface, but they do not need to be included, and different types of refractory aggregates depending on the particle size may be used to configure the particle size distribution. The weight ratio regulating the composition of the refractory aggregate and the refractory binder is determined by using the liquid refractory binder as the transport medium and the refractory fiber threads, strings, tapes, or cloths, or layers made of these, as described above. In order to allow the infiltration of such refractory aggregates, and to make the amount of the refractory aggregates adhering to the surface appropriate, it is necessary to form both into a slurry-like or paste-like kneaded product. However, the content of the binder expressed as the solid content after ignition contained in the refractory binder is, when silica sol or hydrolyzed ethyl silicate is kneaded into a slurry or paste, the coating layer is strengthened. The higher the content, the better. Usually, the maximum content that can be stably obtained is 30% by weight for the former and 40% by weight for the latter. The minimum impregnation should be at least 5% by weight to produce an effect, and the maximum possible impregnation should be 10% by weight, and for fireclays it should be 30 to 40% by weight to form a slurry to pasty mixture when mixed with water. Weight % is suitable. When the thickness of the refractory covering the pipe is less than 2 mm, the effect of reducing the wear rate during use is weak, and even when the thickness exceeds 15 mm, the effect does not increase as the thickness increases.
Thread made of fireproof fiber to obtain that thickness practically,
The diameter or thickness of the string, tape or cloth in its natural state (without tension) is between 0.5 and 15 mm. In addition, the reason why the fire resistance of the refractory is set to 1800K or higher is that, first, the refractory is bonded only by the bonding force of the refractory binder blended, and the fire resistance is This is a limitation to prevent damage to the refractory during heating and cooling due to the generation of new bonding force caused by temperature rise due to insufficient temperature.Secondly, when the molten metal to be applied is hot metal. Its temperature is approximately 1600K, but the molten surface of the slag layer covering it is also 1600K, and since it is molten slag, the refractory must be at least 1800K in order to withstand melting damage caused by this. Third, when it is molten aluminum or its alloys, the conditions of use are immersion in 900-1000K molten metal containing chlorine, hydrogen chloride or aluminum chloride, so the fire resistance of oxide refractories withstands it. This is because the temperature must also be 1800K or higher, and this can be achieved by each of the three types of materials mentioned above being composed of the components listed for each.

In the above-mentioned materials, they are often used as refractory fibers and refractory binders, and are also used in the prior art documents mentioned above. The former uses asbestos, the latter uses sodium silicate or potassium silicate, and the former uses blue asbestos, which itself has little loss on burning, and in addition, amosite, which does not contain alkali groups, is used as thread.
When processing into strings, tapes or fabrics, it is necessary to mix too much organic matter, mainly adhesive, resulting in excessive loss on ignition, and the latter is difficult to mix into the fire-resistant fibers and fire-resistant aggregates. None of these materials can be used in the present invention since this would still reduce their fire resistance.

The lance pipe of the present application made of such materials is made of existing refractory materials, that is, the refractory aggregate, the refractory binder, the refractory fiber threads, strings, tapes, or cloths that are bonded to each other as described above. When inert gas such as argon or nitrogen is blown into the molten metal, steel pipes (for example, JIS G
STK, SGP series), when blowing oxygen or a mixture of oxygen and an inert gas, use steel pipes with aluminum, chromium, silicon, titanium, or zirconium permeated and diffused on at least the inner surface, or aluminum or chromium on the outer periphery. , steel pipes wrapped with steel plates or strips in which silicon, titanium or zirconium has been permeated and diffused, or steel pipes whose inner surfaces are coated with ceramics, chlorine, carbon tetrachloride, or a mixture of these with an inert gas. When blowing gas, it is an embodiment that makes the present invention more effective to use a tube whose tip is reinforced with enamel treatment to resist chlorine corrosion.Furthermore, by using a ceramic tube, it is possible to achieve the above-mentioned applications. It can be used without asking any questions. Accordingly, the first structure of the lance pipe of the present invention, in which these pipes are coated with the refractory material, is that the refractory aggregate and the refractory binder are kneaded in the form of a slurry or paste, and then the pipe is preliminarily coated with the refractory material. One or two layers of impregnated fire-resistant fiber thread, string, tape or cloth wrapped around the
The second type is thread, string, tape, or cloth made of refractory fibers, which are pre-impregnated and attached by kneading refractory aggregate and refractory binder into a slurry or paste. one or two or more layers wrapped around a tube, the third being the outermost layer of the above two that has been air-dried, with a scorching solid content of 5 to 10% by weight.
A fourth type is a refractory pipe impregnated with silica sol or hydrolyzed ethyl silicate; textile thread, string,
Wrap tape or cloth to apply refractory aggregate in a wet state, apply one or more dry layers, and impregnate and apply the slurry or paste-like kneaded material to the final layer. In both cases, by air drying and then heating drying, the refractory binder is completely gelled, increasing the mechanical strength of the coating layer and reducing the loss on ignition. When forming multiple layers using refractory fiber yarn or string, winding each layer in the opposite direction (right-handed, left-handed) increases the gap between the layers and creates a bond between the steel pipe and the coating. It is effective for alleviating stress caused by the difference in expansion coefficient with refractories, and
It is also natural in construction. Therefore, mixing cotton-like refractory fibers, threads made of refractory fibers, strings, tapes, or cloth scraps into the kneaded material based on these considerations may result in excessive mixing of these fibers lowering the fire resistance of the coated refractory. Unless otherwise specified, it can be regarded as a refractory aggregate and therefore belongs to the scope of the present invention.

Due to the above-mentioned interactions, the lance pipe of the present invention including the embodiments described above has a coating layer that is strong, fire resistant, slag erosion resistant, and heat insulating from room temperature to above the usage temperature, so it can be used. Coupled with the cooling effect of the gas that passes through the inside of the tube, steel tubes can withstand immersion in molten steel at temperatures higher than their melting point.
In addition, the enamel coating on the tip of the steel pipe allows it to withstand chlorine injection into molten aluminum and its alloys, and in the case of ceramic pipes, the thermal shock applied to them during immersion is alleviated, making them suitable for long-term or repeated use. Due to its durability and light weight due to the above-mentioned configuration, it provides better workability compared to conventional products.

The following examples of the invention are presented.

Example 1 A steel pipe (JIS
G STK41), leaving 200 mm at one end, attach a string made of fire-resistant fibers whose main components are approximately 50% each of alumina and silica, reinforced with synthetic chemical fibers, with a diameter of approximately 4 mm in their natural state.
It was wrapped tightly in a single layer under a tension of 10kPa. To the outer surface of the tube, where the layer of refractory fibers was approximately 3.5 mm, 30 parts of frog's eye clay, 30 parts of sintered alumina grains with particle sizes corresponding to 28 mesh, and 40 parts of sintered alumina grains of 48 mesh, respectively, and 40 parts of water were added. The paste-like kneaded material was applied so that the outer surface was smooth, the total thickness of the refractory layer was 4 mm, and the refractory layer was air-dried, and then impregnated with silica sol having a burning solid content of 10% by weight. This lance pipe, which was heated and dried for 500K 0.5 hours only in the final process, has a weight increase of 2.4Kg compared to the weight of the raw steel pipe, which is 6.1Kg. Precisely, oxygen flow rate
It was used under the conditions of 20Nm ² /min and ejaculation time of 10 minutes. The average consumption rate of the lance pipe is only 0.2
m/mm, and the remaining half-length part remained sound despite being exposed to an atmosphere of 1850 K or more and radiant heat in the electric arc furnace, and could be used for oxygen blowing in the next melting. The condition after use, in which 40 mm of the tip of the steel pipe was worn away and the refractory pipe was left behind, suggests that the average rate of wear is small. Moreover, the increase in weight did not hinder work.

Example 2 The same steel pipe as used in Example 1, in which 0.3 mm of aluminum was diffused into the inner surface only, was reinforced with steel wire, leaving 200 mm at one end on the outer periphery.Mainly made of approximately 60% alumina and approximately 40% silica. A string made of fire-resistant fiber with a diameter of 3 mm in its natural state is scorched under a tension of approximately 20 kPa, and 1 part by weight of hydrolyzed ethyl silicate with a solid content of 30% by weight, 0.5 part by weight of alumina sol, - 3 parts by weight of finely powdered alumina of 325 mesh was successively immersed in a tank containing slurry mixed with 3 parts by weight of finely powdered alumina, and then tightly rolled up, immediately sprinkled with alumina grains of 48 to 65 mesh, air dried to form the first layer, and sprinkled. A second layer is formed by a similar process using particles of 65 to 200 mesh, and then the slurry is applied,
After air drying, it was heated and dried at 500K to obtain a lance pipe with a 6 mm thick refractory coating layer. This lance pipe, which had a weight increase of 4.2 kg compared to the steel pipe, was used for oxygen blowing in a 30 ton electric arc furnace for melting SUS304 under the conditions of an oxygen flow rate of 25 Nm ² /min and a blowing time of 15 min. We obtained similar results and observation conditions as in .

Example 3 In Example 1, an enamel film of 1 mm thickness was applied to the inner and outer surfaces within a range of 150 mm at one end using a mixture containing crushed plate glass, cryolite, and feldspar as main components and having a melting point of approximately 1250 K with the addition of a thickener. The same steel pipe (length 1.8 m) was used, leaving 200 mm at the other end, and the first layer was reinforced with synthetic organic fibers, with a diameter of 2 mm in its natural state, containing 50% by weight each of alumina and silica. A string made of fire-resistant fiber, a silicon carbide fiber thread with a diameter of 1 mm as the second layer, silica sol with a burning solid content of 30% by weight, and -200 mesh each.
30% by weight, 40% by weight of 65-100 meshes, the balance
A lance with a fireproof coating layer of 3 mm thickness is made by kneading Shamotsu with a particle size distribution of 28 to 65 mesh and silicon carbide with a similar particle size distribution into a paste, impregnating and adhering it, rolling it tightly, and heating and drying it at 500K. It was made into a pipe. This lance pipe was heated to 900K in a holding furnace with a gas mixture consisting of 30% chlorine and 70% nitrogen by volume.
2hv at a flow rate of 60/min in molten aluminum
(Pouring speed 75Kg/min total casting weight 9 tons) It was used under blowing conditions. Observation after cooling showed that there was no melting damage at the tip of the steel pipe (enamelized part), and it was possible to use it again.

Example 4 A hollow part with an outer diameter of 21.2 mm and a wall thickness as a breakage-resistant reinforcing material.
Insert 2.3 mm, 2.7 m long steel pipes (JIS G STK41) and partially adhere them with alumina cement to connect 6 pipes with an outer diameter of 32 mm and an inner thickness of 4.5 mm.
The entire outer circumference of the 400mm ceramic ceramic tube is made of silicon carbide fiber, which has a diameter of 1mm in its natural state.
of the string under a tension of approximately 15kPa, the amount of silica equivalent
It was successively immersed in a tank containing a slurry containing 1 part by weight of a 15% by weight silica sol solution and 3.5 parts by weight of spinel made of -325 mesh finely powdered magnesia, alumina, and chromium oxide. Immediately, -48 mesh of spinel grains were sprinkled and dried repeatedly to form 5 layers, after which the slurry was impregnated. This lance pipe, heated and dried at 500 K, was immersed for 1.2 m in a hot metal bath at 1650 to 1750 K in a pig iron mixer for 15 mm, and was used for desulfurization operations under the conditions of blowing calcium carbide with nitrogen gas for more than 20 times. Obtained the number of durability.

Claims (1)

[Scope of Claims] 1. 50 to 90% by weight of refractory aggregate having a particle size distribution of -10 mesh, -200 mesh, and 48 to 200 mesh, each containing 15% by weight or more, on the outer periphery of the pipe.
and the remainder, impregnated and attached with a fire-resistant binder consisting of one or more of silica sol, hydrolyzed ethyl silicate, and fire-resistant viscosity suspension water with a solid content of 5 to 40% by weight when scorched. A lance coated with a refractory material having a fire resistance of 1800K or higher and having a thickness of 2 to 15 mm, which is made of thread, string, tape, or cloth made of refractory fiber with a diameter or thickness of 0.5 to 15 mm in its natural state. pipe. 2. A lance pipe as set forth in claim 1, wherein the pipe is a steel pipe. 3. The lance pipe according to claim 1, wherein the pipe is a steel pipe in which aluminum, chromium, silicon, titanium, or zirconium is permeated and diffused. 4. The pipe is a steel pipe whose outer periphery is wrapped with a steel plate or steel band in which aluminum, chromium, silicon, titanium, or zirconium is permeated and diffused, as described in any one of claims 1 to 3. lance pipe. 5. The lance pipe according to any one of claims 1 to 4, wherein the pipe is a steel pipe whose inner surface is coated with ceramics. 6. Claims 1 to 3, which are steel pipes or permeation-diffusion-treated steel pipes with enamel coating applied to the vicinity of the gas outlet end of the pipe, or a short pipe with enamel coating applied to the gas outlet end. A lance pipe described in any of the paragraphs. 7. The lance pipe as set forth in claim 1, wherein the pipe is a ceramic pipe having a fire resistance of 1800K or higher and a thermal shock resistance of 0.05 mK/s or higher.