阅读说明：本技术 一种铝工业用萤石基浇注料及其制备方法 (Fluorite-based castable for aluminum industry and preparation method thereof ) 是由 刘小团 何胜平 于 2021-11-08 设计创作，主要内容包括：本发明属于铝工业熔炼技术领域,更具体的涉及一种铝工业用萤石基浇注料及其制备方法。其技术要点如下：按照重量百分比计算,包括如下组分：萤石：65%～75%、Al-(2)O-(3)：8%～12%、CaO：3%～6%、铝酸盐水泥：5%～8%、SiC/Si-(3)N-(4)：7%～10%、Al(OH)-(3)：0.5～0.8%、减水剂0.1～0.3%和防爆纤维0.06～0.1%。本发明以萤石骨料和细粉为主要原料,解决了高温下部分萤石分解消散的问题,使得耐火材料与铝液接触时仍具有非常优异的抗粘铝特性。(The invention belongs to the technical field of aluminum industrial smelting, and particularly relates to a fluorite-based castable for aluminum industry and a preparation method thereof. The technical points are as follows: the composition comprises the following components in percentage by weight: fluorite: 65% -75% of Al 2 O 3 : 8% -12%, CaO: 3% -6% of aluminate cement: 5% -8% of SiC/Si 3 N 4 ：7%~10%、Al（OH） 3 : 0.5-0.8% of water reducing agent, 0.1-0.3% of water reducing agent and 0.06-0.1% of explosion-proof fiber. The invention takes fluorite aggregate and fine powder as main raw materials, solves the problem of decomposition and dissipation of the fluorite at high temperature, and ensures that the refractory material still has excellent anti-aluminum adhesion property when contacting with aluminum liquid.)

1. A fluorite based castable for aluminum industry is characterized by comprising the following components in percentage by weight: fluorite: 65% -75% of Al₂O₃: 8% -12%, CaO: 3% -6% of aluminate cement: 5% -8% of SiC/Si₃N₄：7%~10%、Al（OH）₃: 0.5-0.8% of water reducing agent, 0.1-0.3% of water reducing agent and 0.06-0.1% of explosion-proof fiber.

2. The fluorite-based castable for aluminum industry according to claim 1, wherein the fluorite has a particle size of 0.045 mm-5 mm, wherein CaF₂The content is more than or equal to 95 percent.

3. A fluorite-based castable used in aluminum industry according to claim 1,the alumina is alpha-Al₂O₃The particle size is 1.8 to 2.5 μm.

4. A fluorite based castable for aluminum industry according to claim 3, wherein said α -Al is selected from the group consisting of₂O₃The content of alumina is more than 99.7 percent, and the content of sodium oxide is less than 0.10 percent.

5. A fluorite based castable material for aluminium industry according to claim 1, wherein said aluminate cement has a particle size < 11 μm.

6. The fluorite-based castable material for aluminum industry according to claim 1, wherein said SiC/Si is characterized in that₃N₄In (C) SiC and Si₃N₄The mass ratio of (A) to (B) is 3: 1.

7. A fluorite based castable in aluminum industry according to claim 6, wherein said SiC/Si is selected from the group consisting of₃N₄The particle size of (A) is 0.075-1 mm.

8. A preparation method of a fluorite-based castable for aluminum industry is characterized by comprising the following operation steps:

s1, screening fluorite to obtain a fluorite fine material with the particle size of 0.045 mm-1 mm and a fluorite coarse material with the particle size of 1 mm-5 mm;

s2, mixing fluorite fine material and Al₂O₃CaO, aluminate cement, SiC/Si₃N₄Water reducing agent and Al (OH)₃Adding the mixture into a mixer for premixing;

and S3, mixing the premixed material obtained in the step S2, the explosion-proof fiber and the fluorite coarse material in a forced mixer.

9. The method of claim 8, wherein in step S2, the SiC/Si is first mixed with the casting material₃N₄And Al₂O₃Putting the mixture into a star-shaped ball mill for ball milling to obtain SiC/Si₃N₄And Al₂O₃A mixture of (a).

10. The method for preparing a fluorite based castable in aluminum industry according to claim 8, wherein a ball milling solvent is added during ball milling, and the ball milling solvent is amines or alcohols.

Technical Field

The invention belongs to the technical field of aluminum industrial smelting, and particularly relates to a fluorite-based castable for aluminum industry and a preparation method thereof.

Background

The unshaped refractory material for the traditional aluminum melting furnace is easy to be wetted by aluminum liquid, pollutes the aluminum liquid, and in the running process of the furnace, the aluminum liquid can permeate into cracks of a furnace lining to influence the safety of the furnace; although the temperature of aluminum liquid and aluminum alloying in the aluminum smelting furnace is only 700-900 ℃, the activity of magnesium, zinc, lithium and the like in aluminum and aluminum alloy thereof is very high, and the aluminum alloy thereof can easily react with elements such as silicon, potassium, sodium and the like in a refractory material to be polluted by the refractory material; the fluidity of the molten aluminum metal is excellent, the viscosity of the molten aluminum at 750 ℃ is only 0.104 pas, and the viscosity of the molten aluminum metal is quite close to the viscosity of water at 20 ℃ (0.1 pas), which is the reason why the molten aluminum metal is easy to permeate into the lining. Barium sulfate and a small amount of fluorite are mostly selected as aluminum liquid penetrant for the unshaped refractory material for the aluminum melting furnace in the current market, but the fluorite is easy to decompose at high temperature, so that the castable is poor in aluminum adhesion resistance and easy to crack.

In view of the defects of the existing refractory materials, the inventor develops a fluorite-based castable for aluminum industry and a preparation method thereof based on years of abundant experience and professional knowledge of the materials, and together with theoretical analysis, research and innovation, so as to meet the strict requirements of purity and process of aluminum alloy.

Disclosure of Invention

The invention aims to provide a fluorite-based castable for aluminum industry, which can be used for parts directly contacting with aluminum liquid, including parts of an aluminum melting furnace molten pool, a lower furnace wall, an aluminum water bag lining, an aluminum water launder and the like, and the fluorite is used as a main aggregate, so that the obtained castable has strong aluminum liquid infiltration resistance, reduces the adhesion and infiltration of the aluminum liquid to refractory materials, avoids material cracking caused by the aluminum liquid infiltrating into the refractory materials, and greatly prolongs the service life of a furnace lining.

The technical purpose of the invention is realized by the following technical scheme:

the invention provides a fluorite-based castable for aluminum industry, which comprises the following components in percentage by mass: fluorite: 65% -75% of Al₂O₃: 8% -12%, CaO: 3% -6%, aluminate cement: 5% -8% of SiC/Si₃N₄：7％～10％、Al(OH)₃: 0.5-0.8% of water reducing agent, 0.1-0.3% of water reducing agent and 0.06-0.1% of explosion-proof fiber. According to the invention, the fluorite aggregate and the fluorite fine powder are used as main raw materials, and the aluminum hydroxide is added, so that the problem of decomposition and dissipation of the fluorite at high temperature is solved, and the refractory material still has excellent anti-aluminum adhesion property when contacting with aluminum liquid.

Preferably, the particles of fluoriteThe diameter is 0.045 mm-5 mm, wherein CaF₂The content is more than or equal to 95 percent.

Preferably, the alumina is α -Al₂O₃The particle size is 1.8 to 2.5 μm. The fluorite can be partially decomposed at high temperature to generate fluorine gas, the environment is polluted, and simultaneously, the impermeability of the castable to molten aluminum is reduced₂O₃Micro powder of alpha-Al due to high purity and low sodium₂O₃The micro powder has large specific surface area and high activity, and can generate displacement reaction with fluorine gas at high temperature: 2Al₂O₃+6F＝2AlF₃+3O₂Generated AlF₃The aluminum liquid can be uniformly dispersed into gaps of the material, the compactness of the casting material is improved, and the penetration of the aluminum liquid is prevented; however, the casting material contains 15% of bound water, and the bound water is released at high temperature and meets AlF₃HF can be generated to corrode the castable and the impermeability of the castable is reduced again, a small amount of aluminum hydroxide is added into the castable, and gaseous hydrofluoric acid reacts with the aluminum hydroxide at 400-700 ℃ to generate fluoroaluminate H₃AlF₆Which is then reacted with Na in the refractory material at elevated temperature₂The impurities O generate the cryolite which is high temperature resistant and small in grain size and can be filled into fine gaps of the casting material, so that the compactness of the casting material is improved, and when the casting material encounters fine grains generated by cold and hot alternation, the further development and extension of the fine grains can be blocked by the cryolite grains. Thoroughly solves the problem that the fluorine gas generated by fluorite decomposition causes the permeability resistance of the castable to be reduced, and simultaneously avoids mixed crystal Na₂O forms a low melting point substance with other raw materials at high temperature, and lowers the refractoriness of the refractory.

Preferably, the fluorite-based castable provided by the invention also comprises 0.5-0.8% of sodium aluminate by mass fraction, and the addition of the sodium aluminate can promote the generation of cryolite and avoid fluoroaluminate H₃AlF₆Corrosion of other components in the casting material.

Preferably, alpha-Al₂O₃The content of alumina is more than 99.7 percent, and the content of sodium oxide is less than 0.10 percent. The sodium content in the alumina micro powder can form a low-melting-point substance with other raw materials at high temperatureThe refractoriness of the refractory material is reduced, the material is easy to crack, and convenience is provided for aluminum liquid to permeate into the refractory material, and the high-purity low-sodium alumina micro powder selected by the invention avoids the situation. Due to the alpha-Al₂O₃The micro powder has small particle size, so the micro powder has excellent specific surface area and sintering activity, and can easily react with fluorite and other raw materials in a system at high temperature to generate rod-shaped or acicular mullite and CA/CA₂/CA₆And the mullite not only has excellent high-temperature volume stability, but also can densify the material, reduce the porosity of the material and improve the aluminum liquid permeation resistance of the material; and CA/CA₂/CA₆The materials do not react with molten aluminum, and the high-temperature mechanical strength and the aluminum liquid corrosion resistance of the material can be obviously improved.

Preferably, the particle size of the aluminate cement is less than 11 μm. CA/CA in aluminate cement₂/C₁₂A₇The mineral phase is non-reactive with molten aluminum and has excellent anti-aluminum adhesion property; meanwhile, the aluminate cement can also improve the normal temperature strength of the material, has a promoting effect on high-temperature sintering of the material, and ensures that the material has good medium-high temperature performance.

Preferably, SiC/Si₃N₄In (C) SiC and Si₃N₄The mass ratio of the silicon carbide to the aluminum nitride is 3:1, preferably, the silicon carbide content is 75.4%, the silicon nitride content is 22.8%, the silicon nitride and silicon carbide combined composite material has the excellent high-temperature cold and heat impact resistance and high-temperature abrasion resistance of silicon carbide, has the excellent non-stick aluminum liquid property of silicon nitride, is stable in chemical property, has the room-temperature rupture strength 4-8 times that of a common refractory material, and has a thermal expansion coefficient half that of the common refractory material. The composite material can improve the thermal shock stability of a refractory product, has excellent metal permeation resistance of aluminum, zinc, lead, tin, copper and the like, and also has excellent high-temperature creep resistance, acid resistance, alkali resistance and oxidation resistance.

Preferably, SiC/Si₃N₄The particle size of (A) is 0.075-1 mm.

The second purpose of the invention is to provide a preparation method of the fluorite-based castable for the aluminum industry, which has the same function.

The invention provides a preparation method of a fluorite-based castable for aluminum industry, which comprises the following operation steps:

s1, screening fluorite to obtain a fluorite fine material with the particle size of 0.045 mm-1 mm and a fluorite coarse material with the particle size of 1 mm-5 mm; the mass ratio of the fluorite fine powder to the fluorite coarse material is 40% to 60%.

S2, mixing fluorite fine material and Al₂O₃CaO, aluminate cement, SiC/Si₃N₄Water reducing agent and Al (OH)₃Adding the mixture into a mixer for premixing;

the advantages of premixing the fluorite fine powder and other fine powder raw materials in advance are as follows: because the specific surface area of the fine powder is far larger than that of the particles, the fine powder is subjected to sintering reaction before the coarse material at high temperature, and the premixed fine powder is uniformly distributed in the material, so that the maximum generation of each reaction product at high temperature can be ensured; on the other hand, the situation that some fluorite fine powder is coated on the surface of the fluorite coarse material in the mixing process without premixing tends to be caused, so that the addition amount of the fluorite fine powder is reduced invisibly, and the anti-adhesion fresh aluminum fruits of the material are influenced. Even if the premixed fine powder is coated on the surface of the coarse material, the generation of a reaction product can be still ensured at high temperature due to the uniform mixture of the fluorite fine powder and other fine powder, and the aluminum liquid permeation resistance of the material can be ensured.

And S3, mixing the premixed material obtained in the step S2, the explosion-proof fiber and the fluorite coarse material in a forced mixer.

Preferably, in step S2, SiC/Si is first added₃N₄And Al₂O₃Putting the mixture into a star-shaped ball mill for ball milling to obtain SiC/Si₃N₄And Al₂O₃A mixture of (a). Due to SiC/Si₃N₄The hardness is far higher than that of Al₂O₃During the ball milling process, part of the impact enters Al₂O₃Inside the crystal, Al₂O₃Coated with SiC/Si₃N₄Surface, forming a core-shell like structure, Al at high temperature₂O₃Can be used as a binder to improve SiC/Si₃N₄And fluorite and aluminate cement, furtherHigh compactness of the casting material.

Preferably, a ball milling solvent is added during ball milling, and the ball milling solvent is amines or alcohols.

Preferably, the premixing time of the mixer in the step S2 is 5 min.

Preferably, the mixing time of the forced mixer in the step S3 is 10min, and if the raw materials are agglomerated and not uniformly mixed in the step S3, the raw materials need to be mixed for 3-5 min.

In conclusion, the invention has the following beneficial effects:

1. the refractory material developed by taking fluorite as a main raw material has excellent aluminum liquid permeation resistance, can greatly prolong the service life of the refractory material under various working conditions of contact of molten metal and aluminum, and develops a new idea for subsequent reasonable utilization of domestic fluorite ores.

2. At present, fluorite with the proportion of 1.5-5% is introduced into the conventional refractory material for aluminum melting in the market as an aluminum liquid permeation resistant agent, but the fluorite is easy to dissipate due to decomposition at high temperature, so that the aluminum adhesion resistant effect of the material is greatly reduced, and the service life of the refractory material is greatly reduced. The invention takes fluorite aggregate and fine powder as main raw materials, solves the problem of decomposition and dissipation of the fluorite at high temperature, and ensures that the refractory material still has excellent anti-aluminum adhesion property when contacting with aluminum liquid.

3. The introduction of the silicon nitride and silicon carbide composite material can not only enhance the toughness of the material at high temperature, but also improve the cold and hot impact resistance of the material, prevent the material from being cracked in the use process to cause the damage of the resistant material, and simultaneously the composite material has excellent aluminum adhesion resistance and aluminum liquid slag corrosion resistance; high purity low sodium alpha-Al₂O₃The addition of the micro powder and the aluminate cement can obviously improve the high-temperature rupture strength and compressive strength of the material, alpha-Al₂O₃The micro powder can fill pores in the material at high temperature, improve the compactness of the material, reduce the porosity of the material, improve the use strength and the anti-aluminum-sticking property of the material, effectively prevent the adhesion damage of slag to the refractory material, greatly prolong the service life of the refractory material, reduce the labor intensity of field workers for deslagging, and avoid the slag from being removedThe heat in the smelting equipment is dissipated, and the energy is saved and the environment is protected.

4. Fluorine gas is generated after fluorite is decomposed at high temperature and is dissipated into the atmosphere to pollute the environment, gaps and holes are generated in the refractory material after the fluorite is decomposed, and the impermeability of the refractory material to aluminum liquid is reduced.

Detailed Description

To further illustrate the technical means and effects adopted by the present invention to achieve the predetermined objects, the embodiments, features and effects of the fluorite based castable for aluminum industry and the preparation method thereof according to the present invention are described in detail below.

Example 1: fluorite-based castable for aluminum industry and preparation method thereof

A fluorite based castable for aluminum industry comprises the following components in percentage by weight: fluorite 71%, high purity low sodium alpha-Al₂O₃9% of micro powder, 8% of aluminate cement and SiC/Si₃N₄11 percent, water reducing agent 0.3 percent, explosion-proof fiber 0.1 percent and Al (OH)₃ 0.6％。

The preparation method comprises the following operation steps:

s1, screening fluorite to obtain a fluorite fine material with the particle size of 0.045 mm-1 mm and a fluorite coarse material with the particle size of 1 mm-5 mm;

s2, mixing fluorite fine material and Al₂O₃CaO, aluminate cement, SiC/Si₃N₄Water reducing agent and Al (OH)₃Adding into a mixer for premixing for 5 min;

s3, putting the premixed material obtained in the step S2, the explosion-proof fiber and the fluorite coarse material into a forced mixer to be mixed for 10 min.

Example 2: a fluorite based castable for aluminum industry comprises the following components in percentage by weight: fluorite 73%High purity low sodium alpha-Al₂O₃8% of micro powder, 7% of aluminate cement and SiC/Si₃N₄10 percent, water reducing agent 0.3 percent, explosion-proof fiber 0.1 percent, Al (OH)₃0.8% and sodium aluminate 0.8%.

The preparation method comprises the following operation steps:

s1, screening fluorite to obtain a fluorite fine material with the particle size of 0.045 mm-1 mm and a fluorite coarse material with the particle size of 1 mm-5 mm;

s2, mixing fluorite fine material and Al₂O₃CaO, aluminate cement, SiC/Si₃N₄Water reducing agent and Al (OH)₃Adding into a mixer for premixing for 5 min;

s3, putting the premixed material obtained in the step S2, the explosion-proof fiber and the fluorite coarse material into a forced mixer to be mixed for 10 min.

Example 3: a fluorite based castable for aluminum industry comprises the following components in percentage by weight: fluorite 78%, high purity low sodium alpha-Al₂O₃7% of micro powder, 5% of aluminate cement and SiC/Si₃N₄9 percent of water reducing agent, 0.3 percent of water reducing agent, 0.1 percent of explosion-proof fiber, Al (OH)₃ 0.6％。

The preparation method comprises the following operation steps:

s1, screening fluorite to obtain a fluorite fine material with the particle size of 0.045 mm-1 mm and a fluorite coarse material with the particle size of 1 mm-5 mm;

s2, mixing SiC/Si₃N₄And Al₂O₃The SiC/Si is obtained by ball milling in a star type ball mill₃N₄And Al₂O₃Taking out the mixture, drying, mixing with fluorite fines, CaO, aluminate cement, water reducing agent and Al (OH)₃Adding into a mixer for premixing for 5 min;

s3, putting the premixed material obtained in the step S2, the explosion-proof fiber and the fluorite coarse material into a forced mixer to be mixed for 10 min.

Comparative example 1: conventional aluminum-dissolving pouring material in market

Comparative example 2:

the formulations of the components in this comparative example did not contain Al (OH)₃The contents of other components were the same as in example 1, and the method for producing the castable was the same as in comparative example 1.

Comparative example 3:

the formula of the components in the comparative example does not contain sodium aluminate, the content of other components is consistent with that in the example 2, and the preparation method of the castable is also consistent with that in the comparative example 2.

Comparative example 4:

the component formulation in this comparative example is identical to example 1.

The preparation method of the castable comprises the following steps:

s1, mixing fluorite and Al₂O₃CaO, aluminate cement, SiC/Si₃N₄Water reducing agent and Al (OH)₃Adding into a mixer for premixing for 5 min;

s2, putting the premixed material obtained in the step S2, the explosion-proof fiber and the fluorite coarse material into a forced mixer to be mixed for 10 min.

Performance testing

Adding water into the samples of the above examples 1 to 3 and comparative examples 1 to 4 according to respective standards to prepare a standard test block with the size of 40 × 40 × 160mm, a sample cup with the size of 120mm outside phi, 100mm inside phi and 60mm H, testing the fluidity according to GB/T2419-2016, testing the solidification time according to GB/T1346-2011, testing the breaking strength according to GB/T3001-2007, testing the compressive strength according to GB/T5072-2008, testing the thickness and the corrosion rate of a reaction layer of the sample cup immersed in aluminum liquid at high temperature according to YB/T4161-2007 (2017) to judge the aluminum permeation resistance of the material, wherein the test results are shown in the following table:

in the test, ALCOA 7075 standard aluminum alloy is selected for carrying out an aluminum liquid corrosion resistance test. When the thickness of the reaction layer of the sample cup and the molten aluminum is lower than the ablation rate, the better the non-stick aluminum performance of the material is proved, otherwise, the worse the non-stick aluminum performance is; from the results of the reaction thickness between the aluminum liquid with 1000 ℃ and @72hrs and the refractory in the table, the performances of examples 1, 2 and 3 are far lower than those of the conventional refractory for aluminum melting in the market, and the best performance is obtained in example 2. At present, most of aluminum and aluminum alloys in the market are smelted at the temperature of 700-850 ℃, the viscosity of the molten metal can be reduced at the test temperature of 1000 ℃, the permeability of the molten metal to the refractory material is enhanced, the use condition of the refractory material is more strict, the aluminum adhesion resistance effect of the refractory material can be quickly obtained, and the aluminum adhesion resistance effect of the newly invented fluorite-based castable is in the leading level in the market.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.