An anti-oxidation release agent for producing a machine-pressed carbon-containing shaped product and a preparation method and application thereof

Abstract

The present application relates to the steel smelting industry, the refractory technology field for steelmaking, in particular to an anti-oxidation release agent for machine-pressing carbon-containing shaped products, a preparation method and application thereof. The anti-oxidation release agent is prepared from the following raw materials in parts by weight: boric acid 8-15 parts, silicon powder 20-40 parts, ultra-fine graphite 1-5 parts, glass powder 30-50 parts, gypsum powder 1-10 parts, thickening agent 0.2-1 part, and clay powder 1-10 parts. The anti-oxidation release agent solves the problems of difficult cleaning, flammability and explosion safety of traditional release agents (usually flammable oil products), and the problems of complicated anti-oxidation coating construction and difficult execution, and finally solves the problem of carbon-containing machine-pressing refractory baking decarburization, and improves the service life of the refractory.

Description

Technical Field

[0001] This invention relates to the steel smelting industry, specifically to an anti-oxidation release agent for the production of machine-pressed carbon-containing molded products, its preparation method, and its application. Background Technology

[0002] Refractory materials are indispensable lining materials for high-temperature containers in the steelmaking process. Among them, carbon-containing shaped refractory materials have a wide range of applications due to their good high-temperature properties such as thermal shock resistance and erosion resistance, and are present in almost every stage from ironmaking to steelmaking.

[0003] The rapid development of society has placed higher demands on all industries, and competition has become increasingly fierce. Nowadays, improving quality, reducing consumption, and increasing efficiency are the main tasks of business operations.

[0004] The carbon-containing shaped refractory materials described in this invention mainly refer to ladle magnesia-carbon slag line bricks, converter magnesia-carbon bricks, and iron ladle aluminum silicon carbide carbon bricks. The above series of products are currently products with relatively mature formulation systems, but there is still a difficult defect to solve. During the medium-temperature baking process before the products are put into production, because the baking environment cannot isolate oxygen, some steel plants even spray oxygen during baking in order to improve baking efficiency, which causes serious decarburization of the carbon-containing working lining surface, making the structure loose and losing strength, seriously affecting the service life of the refractory materials.

[0005] To address this issue, the commonly used approach is to pre-apply an anti-oxidation coating to the working lining surface. However, due to the overly complicated construction process and the difficulty in ensuring construction quality, this method is no longer widely adopted. Summary of the Invention

[0006] To address the above problems, this invention develops an anti-oxidation release agent for the production of machine-pressed carbon-containing molded products. It also solves the production safety issues of traditional release agents (generally flammable and explosive products) being difficult to clean and flammable, as well as the problems of cumbersome and difficult-to-implement anti-oxidation coating construction. Ultimately, it solves the problem of decarburization during baking of carbon-containing machine-pressed refractories and improves the service life of the refractories.

[0007] To achieve the above objectives, the present invention employs the following technical solution: An anti-oxidation release agent for the production of machine-pressed carbon-containing molded products is composed of the following raw materials in parts by weight: boric acid: 8-15 parts, silica powder: 20-40 parts, ultrafine graphite: 1-5 parts, glass powder: 30-50 parts, gypsum powder: 1-10 parts, thickener: 0.2-1 parts, and clay powder: 1-10 parts.

[0008] The boric acid is a white, semi-transparent crystalline solid with a particle size <0.5 mm, of which H3BO3 ≥98%.

[0009] The silicon micro powder is 95% silicon micro powder, with SiO2 ≥ 95% and median diameter D. 50 ≤1.0μm, specific surface area: 15~20m² 2 / g.

[0010] The ultrafine graphite is -895 graphite, with fixed carbon ≥95%, 800 mesh pass rate ≥90%, and D... 90 : 15.0μm±0.5μm.

[0011] The glass powder is borosilicate glass powder with SiO2 ≥ 98%, softening point 450~600℃, and sintering temperature 600~700℃.

[0012] The gypsum powder is ultrafine gypsum powder with a 1500 mesh passing rate of ≥95%.

[0013] The thickener is sodium hydroxymethyl cellulose.

[0014] The clay is ball clay, with SiO2 content of 58%–65%, Al2O3 content of 21%–28%, and particle size of ≥90% (230 mesh).

[0015] A method for preparing an anti-oxidation release agent for the production of machine-pressed carbon-containing molded products, specifically comprising: 1) Add the pre-prepared boric acid powder to clean water at 80-100℃ at a weight ratio of 1:3-5 and stir for 10-20 minutes to fully dissolve it, ensuring that there is a small amount of undissolved boric acid at the bottom of the water. Prepare a saturated boric acid solution and cool it for later use. 2) Mix all raw materials except boric acid according to the proportions, and use an inclined mixer to mix for 15-30 minutes to ensure uniform mixing, and prepare an anti-oxidation release agent powder for later use; 3) Take an appropriate amount of anti-oxidation release agent powder, add boric acid saturated solution according to the formula ratio, and at the same time, add an appropriate amount of water accounting for 10% to 15% of the weight of the mixture according to the state of the coating. Mix with a mud mixer for 30 to 60 minutes to ensure uniform mixing and make a paint-like colloid with a flow value of 200 to 250 mm.

[0016] 4) The prepared anti-oxidation release agent should be sealed in plastic to prevent dehydration and hardening, and should be used within one week.

[0017] Application of an anti-oxidation release agent for the production of machine-pressed carbon-containing shaped products, the release agent being used for machine-pressed carbon-containing shaped refractories, wherein the carbon-containing shaped refractories include magnesia-carbon slag line bricks for steel ladles, magnesia-carbon bricks for converters, and aluminum silicon carbide carbon bricks for iron ladles.

[0018] Before feeding materials into the brick press, a layer of anti-oxidation release agent is manually brushed onto the surface of the mold cavity. Alternatively, a robot can be used for automatic spraying to replace traditional oil-based release agents. Then, materials are fed into the mold cavity for production as usual.

[0019] Because this release agent contains lubricant (ultrafine graphite) and thickener, and most of the raw materials are ultrafine powders, the product has good fluidity and strong adhesion. Whether it is manually brushed or sprayed by a robot, it can form a uniform release agent coating on the mold cavity surface, thus achieving the purpose of replacing traditional release agents.

[0020] During the production and pressing process, under pressure, a small portion of the release agent will penetrate into the interior of the product surface, while most of it will adhere to the product surface to form a composite anti-oxidation layer.

[0021] Considering that graphite oxidation in an aerobic environment generally begins at 450℃, accelerates significantly at 600℃, and reaches its peak above 800℃, this anti-oxidation release agent incorporates raw materials with different melting point gradients. Boric acid, upon heating to 300–500℃, dehydrates to form amorphous glassy B2O3, densifying the anti-oxidation coating. This ensures a dense protective layer forms before the baking temperature reaches 450℃, reducing the graphite oxidation rate. As the baking temperature gradually increases, borosilicate glass powder begins to soften and melt between 450–600℃. With the increasing amount of molten material, the anti-oxidation coating gradually transforms from a dense protective layer into a glassy sealing layer, ensuring complete oxygen isolation before the baking temperature reaches 600℃, thus preventing graphite oxidation. As the baking temperature continues to rise, the stability of the glassy sealing layer formed at around 1000℃ (the highest baking temperature for refractory products before going online) is ensured by the action of other high refractoriness components in the anti-oxidation coating (such as silica powder > 1600℃, gypsum > 1400℃, and ball clay > 1600℃). This prevents phenomena such as flow and collapse, thus ensuring that the carbon-containing working lining surface does not decarburize.

[0022] Compared with the prior art, the beneficial effects of the present invention are: This invention provides an anti-oxidation release agent for the production of machine-pressed carbon-containing molded products, its preparation method, and its application. It solves the production safety problems of traditional release agents (generally flammable and explosive products) being difficult to clean and flammable, as well as the problems of cumbersome and difficult-to-implement anti-oxidation coating construction. Ultimately, it solves the problem of decarburization during baking of carbon-containing machine-pressed refractory materials and improves the service life of refractory materials.

[0023] Practical use has proven that the carbon-containing products produced by this invention can achieve the property of not decarburizing during baking, effectively reducing the decarburization loss of refractory materials during baking, and significantly improving service life. Detailed Implementation

[0024] The present invention will be further described below with reference to the embodiments: The following embodiments provide a detailed description of the present invention. These embodiments are merely descriptions of the best implementation of the present invention and do not limit the scope of the present invention.

[0025] The raw material formulations of the release agent in the examples are shown in Table 1, the raw material indicators in the examples are shown in Table 2, and the product testing indicators in the examples are shown in Table 3.

[0026] Table 1. Raw material formulation of the release agent in the examples: Table 2 Raw material indicators for the examples: Table 3. Application Product Testing Indicators: Note: 1. The release agent used in the comparative example is 0# diesel oil.

[0027] 2. The pressure resistance and decarburization layer thickness test data in the table are laboratory data, while the service life is actual application data.

[0028] summary: 1. Steel ladle magnesia-carbon slag line bricks, converter magnesia-carbon bricks, and iron ladle aluminum silicon carbide carbon bricks produced using the release agent of this invention exhibit virtually no difference in strength after drying at 200°C before leaving the factory. However, after baking at 1100°C, the overall compressive strength decreases because the organic binder (phenolic resin) in the refractory material carbonizes while other components have not yet reached their sintering temperature. If significant decarburization occurs, the compressive strength will drop sharply. Steel ladle magnesia-carbon slag line bricks, converter magnesia-carbon bricks, and iron ladle aluminum silicon carbide carbon bricks produced using the release agent of this invention have virtually no decarburization layer and form a dense glassy closed layer on the outer surface, resulting in minimal loss of compressive strength.

[0029] 2. After the ladle magnesia-carbon slag line bricks, converter magnesia-carbon bricks, and iron ladle aluminum silicon carbide carbon bricks produced using the release agent of this invention were actually applied in a 200-ton ladle, converter, and iron ladle of a steel plant, the service life of the ladle magnesia-carbon slag line bricks and iron ladle aluminum silicon carbide carbon bricks was significantly improved, reaching more than 10%. The converter, due to its long service life and the fact that its service life is closely related to the steel grade smelted later and the level of maintenance, cannot be directly evaluated.

Claims

1. An anti-oxidation release agent for the production of machine-pressed carbon-containing molded products, characterized in that, It is prepared from the following raw materials in parts by weight Composition: Boric acid: 8-15 parts, silica powder: 20-40 parts, ultrafine graphite: 1-5 parts, glass powder: 30-50 parts, gypsum powder: 1-10 parts, thickener: 0.2-1 parts, clay powder: 1-10 parts.

2. The anti-oxidation release agent for the production of machine-pressed carbon-containing molded products according to claim 1, characterized in that, The boric acid is a white, semi-transparent crystalline solid with a particle size <0.5 mm, of which H3BO3 ≥98%.

3. The anti-oxidation release agent for the production of machine-pressed carbon-containing molded products according to claim 1, characterized in that, The silicon micro powder is 95% silicon micro powder, with SiO2 ≥ 95% and median diameter D. 50 ≤1.0μm, specific surface area: 15~20m² 2 / g.

4. The anti-oxidation release agent for the production of machine-pressed carbon-containing molded products according to claim 1, characterized in that, The ultrafine graphite is -895 graphite, with fixed carbon ≥95%, 800 mesh pass rate ≥90%, and D... 90 : 15.0μm±0.5μm.

5. The anti-oxidation release agent for the production of machine-pressed carbon-containing molded products according to claim 1, characterized in that, The glass powder is borosilicate glass powder with SiO2 ≥ 98%, softening point 450~600℃, and sintering temperature 600~700℃.

6. The anti-oxidation release agent for the production of machine-pressed carbon-containing molded products according to claim 1, characterized in that, The gypsum powder is ultrafine gypsum powder with a 1500 mesh passing rate of ≥95%.

7. The anti-oxidation release agent for the production of machine-pressed carbon-containing molded products according to claim 1, characterized in that, The thickener is sodium hydroxymethyl cellulose.

8. The anti-oxidation release agent for the production of machine-pressed carbon-containing molded products according to claim 1, characterized in that, The clay is ball clay, with SiO2 content of 58%–65%, Al2O3 content of 21%–28%, and particle size of ≥90% (230 mesh).

9. A method for preparing an anti-oxidation release agent for the production of machine-pressed carbon-containing molded products as described in any one of claims 1-8, characterized in that, Specifically, it includes: 1) Add boric acid powder to water at 80-100℃ at a weight ratio of 1:3-5 and stir until fully dissolved to prepare a saturated boric acid solution. Cool and set aside for use. 2) Mix all raw materials except boric acid according to the specified proportions to form an anti-oxidation release agent powder for later use; 3) Take the anti-oxidation release agent powder, add the saturated boric acid solution according to the formula ratio, and add water accounting for 10% to 15% of the weight of the mixture. Mix evenly to make a paint-like colloid with a flow value of 200 to 250 mm.

10. The application of an anti-oxidation release agent for the production of machine-pressed carbon-containing molded products as described in any one of claims 1-8, characterized in that, Release agent for press-formed carbon-containing shaped refractories, the carbon-containing shaped refractories including magnesia-carbon slag line bricks for steel ladles, magnesia-carbon bricks for converters, and aluminum silicon carbide carbon bricks for iron ladles.

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