CN107746258B - Ultralow-linear-change baking-free air brick and preparation method and application thereof - Google Patents

Abstract

The invention relates to an ultralow linear change baking-free air brick and a preparation method and application thereof. The air brick is prepared by mixing a mixing agent and an additive, wherein the mixing agent consists of sintered tabular corundum particles, aluminum-rich spinel particles, corundum fine powder, aluminum-rich spinel fine powder, alpha-alumina fine powder, chromium oxide green fine powder, zirconium oxide fine powder and pure calcium aluminate cement. The additive consists of a heat stabilizer, a polycarboxylic acid dispersing water reducer and a mineralizer. According to the invention, the volume shrinkage generated in the sintering process is counteracted by using the volume expansion generated by the solid solution reaction of chromium oxide green and a corundum phase and the chemical reaction of pure calcium aluminate cement and the corundum phase in the using process, and then the phase change toughening effect of zirconium oxide in the reaction process is utilized, the heating permanent linear change rate of the prepared ultralow linear change baking-free air brick is +0.01 to + 0.04%, the air permeability and the blowing effect are effectively improved, and simultaneously, the erosion resistance and the thermal shock resistance of the air brick are superior to those of similar products.

Description

Ultralow-linear-change baking-free air brick and preparation method and application thereof

Technical Field

The invention relates to the technical field of refractory materials, in particular to an ultralow-linear-change baking-free air brick and a preparation method and application thereof.

Background

In recent years, the external refining technology becomes an indispensable important link in modern steel production, and the advantages of the external refining technology are increasingly shown in the aspects of increasing the variety of steel, improving the quality of the steel and the like. The external refining adopts the bottom argon blowing technology, so that the components and the temperature of the molten steel can be uniform, and the physical and chemical reactions of the molten steel refining are promoted. The air brick is the most important functional element in the bottom argon blowing process, the use performance of the air brick is important for the smooth implementation of the bottom argon blowing process, and the reliability and the safety of the external refining process are ensured. With the continuous increase of the requirements of clean steel and high-quality steel, the external refining proportion is increased, the time is prolonged, the working load born by the air brick is increased, and the use conditions are increasingly harsh. The volume stability of the air brick is an important index for measuring the quality of the air brick, the slit of the slit type air brick is narrow, generally about 200um, if the volume change of the air brick in the process of firing or using is large, the size of the slit can be influenced, and the air permeability is not enough or the infiltrated steel cannot be blown open due to the excessively small or large slit width, so that the air permeability and the blowing effect are finally influenced.

At present, the materials of the existing air brick mainly comprise aluminum magnesium chromium, chromium corundum, corundum-spinel and the like. The chromium corundum brick is used as a material of the traditional steel ladle air brick, plays an important role for a long time, but because the traditional chromium corundum brick has insufficient performance in the aspect of thermal shock resistance, cracks are easily generated in the using process, so that molten steel is very easy to invade into a brick body along an air passage generating the cracks to form molten steel permeation, and the argon blowing effect is seriously influenced. In addition, after the chromium corundum brick is used, Cr in the brick³⁺Is oxidized into Cr⁶⁺，Cr⁶⁺Has toxicity and environmental pollution. Therefore, the use of the chromium corundum air brick is limited. The corundum-spinel air brick has excellent performances of good erosion resistance, good thermal shock resistance and the like, can meet the use requirement of the air brick to the maximum extent, but is prepared by sintering at 1500 ℃ or even higher temperature in order to obtain stable volume stability, and has high energy consumption, so that the product cost is higher. The prior air brick is prepared by high-temperature firing, so that the energy consumption is high, the product cost is high, or the baking-free air brick has large linear change rate and poor volume stability in the using process.

Disclosure of Invention

The invention aims to provide an ultralow linear change baking-free air brick, which does not need high-temperature sintering, and has a heating permanent linear change rate of +0.01 to +0.04 percent under the use condition. The air permeability and the blowing effect of the air brick are ensured. Meanwhile, the erosion resistance and the thermal shock resistance of the air brick are superior to those of similar products, and the air brick can replace the existing air brick to be widely used on refined steel ladles.

The second purpose of the invention is to provide a preparation method of the ultralow-linear-change baking-free air brick.

The invention also aims to provide the application of the ultralow-linear-change baking-free air brick in the refining ladle air brick.

The technical scheme adopted by the invention is as follows: an ultralow linear variation burn-free air brick is prepared by mixing a mixing agent and an additive;

the mixture comprises the following components in percentage by weight:

the additive comprises a heat stabilizer, a polycarboxylic acid dispersing water reducing agent and a mineralizer, wherein the addition amount of the heat stabilizer is 0.01-0.03 wt% of the weight of the mixture, the addition amount of the polycarboxylic acid dispersing water reducing agent is 0.04-0.15 wt% of the weight of the mixture, and the addition amount of the mineralizer is 0.01-0.03 wt% of the weight of the mixture.

Preferably, the sintered plate-like corundum particles, Al₂O₃The content of the high-density polyethylene is more than or equal to 98 weight percent, and the volume density is more than or equal to 3.55g/cm³The granularity is less than or equal to 8mm, the closed porosity is 10-20%, and the pore diameter is 3-10 um.

Preferably, the content of MgO in the aluminum-rich spinel particles is 20-26 wt%, and Al is₂O₃The content of (A) is 72-79 wt%, the weight percentage of the impurity content is less than or equal to 2%, and the granularity is less than or equal to 8 mm.

Preferably, said corundum fine powder, Al₂O₃The content of the inorganic nano-particles is more than or equal to 98wt percent, and the granularity is less than or equal to 0.088 mm.

Preferably, in the aluminum-rich spinel micro powder, the content of MgO is 20-26 wt%, and Al is₂O₃The content of the carbon nano-particles is 72-79 wt%, the weight percentage of the content of impurities is less than or equal to 2%, and the median diameter D50 is 5-20 um.

Preferably, the active α -alumina micropowder, Al₂O₃The content of (a) is more than or equal to 98wt%, and the median diameter D50 is 0.5-6 um.

Preferably, the chromium oxide green fine powder, Cr₂O₃The content of the inorganic filler is more than or equal to 98wt percent, and the granularity is less than or equal to 0.044 mm.

Preferably, the fine powder of zirconium oxide, ZrO₂The content of the inorganic nano-particles is more than or equal to 90wt percent, and the granularity is less than or equal to 0.044 mm.

Preferably, the pure calcium aluminate cement, Al₂O₃68-71 wt% of CaO, 29-32 wt% of CaO, and the granularity is less than or equal to 0.044 mm.

Preferably, the heat stabilizer is one or a mixture of more than two of SIS resin, C5 petroleum resin or calcium carbonate; the polycarboxylic acid dispersing water reducing agent is one or a mixture of more than two of sodium gluconate, sodium dodecyl sulfate (K12) and alpha-sodium alkenyl sulfonate (AOS); the mineralizer is one or the mixture of more than two of yttrium oxide, cerium oxide or nitroglycerin.

The preparation method of the ultralow linear change baking-free air brick comprises the following steps:

1) preparing materials according to the proportion;

2) firstly, mixing corundum fine powder, aluminum-rich spinel fine powder, calcium aluminate cement, zirconia fine powder, active alpha-alumina fine powder, polycarboxylic acid dispersing water reducer and chromium oxide green fine powder in a premixer for 3-5 minutes to obtain premixed powder for later use;

3) taking a heat stabilizer and a mineralizer, adding water accounting for 3-4% of the total weight of the heat stabilizer and the mineralizer, and uniformly stirring for later use;

4) putting the sintered tabular corundum particles and the aluminum-rich spinel particles into a mixer, adding the premixed powder obtained in the step 2), dry-mixing for 1-3 minutes, finally adding the mixture obtained in the step 3), and uniformly mixing for 3-8 minutes to obtain a castable;

5) adding the casting material obtained in the step 4) into a mold, carrying out vibration molding, and maintaining for 12-48 hours at the temperature of 20-100 ℃ to obtain a blank;

6) demolding the blank formed in the step 5), and maintaining for 72-240 hours at the temperature of 20-100 ℃ to obtain a sample;

7) and (3) carrying out heat treatment on the sample obtained in the step 6) at the temperature of 450-800 ℃ for 12-48 hours to obtain the ultralow linear change baking-free air brick.

According to the invention, the granularity of the sintered plate-shaped corundum is less than 8mm, the main crystal phase corundum phase has the crystal size of more than 40um, a large number of closed air holes are formed in the crystal, the closed porosity is 10-20%, the aperture is 3-10 um, and the sintered plate-shaped corundum has the characteristics of high melting point, strong erosion resistance, excellent thermal shock stability and the like.

The aluminum-rich spinel has the advantages that the particle size of the aluminum-rich spinel is less than 8mm, the main crystal phase of the magnesium aluminate spinel is a crystal system with an isometric axis, the crystal size is more than 80 mu m, and the aluminum-rich spinel has the characteristics of high melting point, strong erosion resistance, excellent thermal shock stability and the like.

The corundum fine powder has the main crystal phase of corundum phase, the granularity is less than or equal to 0.088mm, and the corundum fine powder has the characteristic of excellent erosion resistance.

According to the invention, the main crystal phase of the active alpha-alumina micro powder is corundum phase, the median diameter D50 is 0.5-6 um, and the active alpha-alumina micro powder has the characteristic of high reaction activity.

According to the invention, ZrO in the fine zirconia powder₂The content is more than or equal to 90 wt%, the main crystal phase is monoclinic zirconia and cubic zirconia, and the granularity is less than or equal to 0.044 mm.

In the pure calcium aluminate cement, Al is₂O₃68-71 wt% of CaO, 29-32 wt% of a main crystal phase CA₂And the hydration speed is slow, the later strength is high, the refractoriness is high, and the granularity is less than or equal to 0.044 mm.

The invention has the beneficial effects that: the invention relates to an ultralow linear change burn-free air brick, which is prepared by taking sintered tabular corundum and aluminum-rich spinel as main raw materials, adding alpha-alumina, chromium oxide green and partially stable zirconium dioxide micropowder, adopting pure calcium aluminate as a binding agent, adding a heat stabilizer, a water reducing agent and an organic mineralizer, and carrying out low-temperature heat treatment. The volume shrinkage generated in the sintering process is counteracted by utilizing the volume expansion generated by the solid solution reaction of the chromium oxide green micro powder and the corundum phase and the chemical reaction of the pure calcium aluminate cement and the corundum phase in the using process, so that the volume stability of the air brick in the using process is controlled, the air permeability and the blowing effect are improved, the phase change toughening effect of part of stable zirconium oxide micro powder in the reaction process is utilized, the toughness of the air brick is increased, and the thermal shock stability of the air brick is improved.

Detailed Description

The present invention will be further described with reference to the following examples.

An ultralow linear variation burn-free air brick is prepared by mixing a mixing agent and an additive;

the mixture comprises the following components in percentage by weight:

the additive consists of a heat stabilizer, a polycarboxylic acid dispersing water reducer and a mineralizer.

The components of the mixing agent are 100 percent in total, and the addition amount of the additive is the percentage of the total weight of the mixing agent, and specifically comprises the following components: the addition amount of the heat stabilizer is 0.01-0.03 wt% of the total weight of the mixture, the addition amount of the polycarboxylic acid dispersing water reducer is 0.04-0.15 wt% of the total weight of the mixture, and the addition amount of the mineralizer is 0.01-0.03 wt% of the total weight of the mixture.

The sintered plate-like corundum particles, Al₂O₃The content of the high-density polyethylene is more than or equal to 98 weight percent, and the volume density is more than or equal to 3.55g/cm³The granularity is less than or equal to 8mm, the closed porosity is 10-20%, and the pore diameter is 3-10 um.

Preferably, the content of MgO in the aluminum-rich spinel particles is 20-26 wt%, and Al is₂O₃The content of (A) is 72-79 wt%, the weight percentage of the impurity content is less than or equal to 2%, and the granularity is less than or equal to 8 mm.

Preferably, said corundum fine powder, Al₂O₃The content of the inorganic nano-particles is more than or equal to 98wt percent, and the granularity is less than or equal to 0.088 mm.

Preferably, in the aluminum-rich spinel micro powder, the content of MgO is 20-26 wt%, and Al is₂O₃The content of the carbon nano-particles is 72-79 wt%, the weight percentage of the content of impurities is less than or equal to 2%, and the median diameter D50 is 5-20 um.

Preferably, the active α -alumina micropowder, Al₂O₃The content of the component (A) is more than or equal to 98wt%, and the median diameter D50 is 0.5-6 um.

Preferably, the chromium oxide green fine powder, Cr₂O₃The content of the inorganic filler is more than or equal to 98wt percent, and the granularity is less than or equal to 0.044 mm.

Preferably, the fine powder of zirconium oxide, ZrO₂The content of the inorganic nano-particles is more than or equal to 90wt percent, and the granularity is less than or equal to 0.044 mm.

Preferably, the pure calcium aluminate cement, Al₂O₃68-71 wt% of CaO, 29-32 wt% of CaO, and the granularity is less than or equal to 0.044 mm.

Preferably, the heat stabilizer is one or a mixture of more than two of SIS resin, C5 petroleum resin or calcium carbonate; the polycarboxylic acid dispersing water reducing agent is one or a mixture of more than two of sodium gluconate, sodium dodecyl sulfate (K12) and alpha-sodium alkenyl sulfonate (AOS); the mineralizer is one or the mixture of more than two of yttrium oxide, cerium oxide or nitroglycerin.

The preparation method of the ultralow linear change baking-free air brick comprises the following steps:

1) preparing materials according to the proportion;

2) firstly, mixing corundum fine powder, aluminum-rich spinel fine powder, pure calcium aluminate cement, zirconia fine powder, active alpha-alumina fine powder, polycarboxylic acid dispersing water reducer and chromium oxide green fine powder in a premixer for 3-5 minutes to obtain premixed powder for later use;

3) taking a heat stabilizer and a mineralizer, adding water accounting for 3-4% of the total weight of the heat stabilizer and the mineralizer, and uniformly stirring for later use;

4) putting the sintered tabular corundum particles and the aluminum-rich spinel particles into a mixer, adding the premixed powder obtained in the step 2), dry-mixing for 1-3 minutes, finally adding the mixture obtained in the step 3), and uniformly wet-mixing for 3-8 minutes to obtain a castable;

5) adding the casting material obtained in the step 4) into a mold, carrying out vibration molding, and maintaining for 12-48 hours at the temperature of 20-100 ℃ to obtain a blank;

6) demolding the blank formed in the step 5), and maintaining for 72-240 hours at the temperature of 20-100 ℃ to obtain a sample;

7) and (3) carrying out heat treatment on the sample obtained in the step 6) at the temperature of 450-800 ℃ for 12-48 hours to obtain the ultralow linear change baking-free air brick.

Examples 1 to 6

The composition of each raw material of the ultralow linear change baking-free air brick is shown in Table 1

TABLE 1

(II) formula of ultralow linear change baking-free air brick as shown in Table 2

TABLE 2

Example 1

Example 2

Example 3

Example 4

Example 5

Example 6

Sintered plate-like corundum particles

30％

35％

40％

45％

50％

55％

Aluminum-rich spinel particles

25％

23％

19％

16％

13％

10％

Corundum fine powder

13％

15％

17％

19％

20％

22％

Aluminum-rich spinel micropowder

16％

14％

12％

10％

8％

6％

Active α -alumina micropowder

8％

6％

5.5％

4％

3.5％

2％

Green and fine chromium oxidePowder

1％

1.5％

2％

2.5％

3％

3.5％

Zirconia fine powder

3％

2.5％

2％

1.5％

1％

0.5％

Pure calcium aluminate cement

4％

3％

2.5％

2％

1.5％

1％

Heat stabilizer

0.01％

0.02％

0.02％

0.01％

0.02％

0.03％

Polycarboxylic acid dispersing water reducing agent

0.04％

0.06％

0.08％

0.10％

0.12％

0.15％

Organic mineralizer

0.01％

0.02％

0.02％

0.03％

0.02％

0.03％

(III) the parameters in the specific preparation method of the ultralow linear change baking-free air brick are shown in Table 3

TABLE 3

(IV) performance of ultralow linear change baking-free air brick

Six conventional performance indexes of apparent porosity, volume density (GB/T2997-2000), normal-temperature compressive strength (GB/T5072-2008), normal-temperature breaking strength (GB/T3001-.

TABLE 4

Application example

The product is used on 100-ton refining ladle furnaces of Dalian steel mills 5#, 7#, 8#, 26#, 36#, and 39# with the air permeability reaching 100%, which shows that the product has strong volume stability in the using process, the service life of the product is longer than that of the existing product, the thickness of the residual bricks after the product is used is longer than that of the existing product, the total refining time is prolonged to 2200min, and the operation efficiency of the ladle is greatly improved. The use condition of the ultralow-line-change baking-free air brick compared with the prior product is shown in table 5.

TABLE 5

Claims (9)

1. An ultralow linear change baking-free air brick is characterized in that the ultralow linear change baking-free air brick is prepared by mixing a mixing agent and an additive;

the mixture comprises the following components in percentage by weight:

40-50 wt% of sintered tabular corundum particles,

13-19 wt% of aluminum-rich spinel particles,

17-20 wt% of corundum fine powder,

8-12 wt% of aluminum-rich spinel micro powder,

3.5 to 5.5 weight percent of active alpha-alumina micro powder,

2-3 wt% of chromium oxide green fine powder,

1-2 wt% of zirconia fine powder,

1.2-2.5 wt% of pure calcium aluminate cement;

the additive comprises a heat stabilizer, a polycarboxylic acid dispersing water reducing agent and a mineralizer, wherein the addition amount of the heat stabilizer is 0.01-0.02 wt% of the total weight of the mixture, the addition amount of the polycarboxylic acid dispersing water reducing agent is 0.08-0.12 wt% of the total weight of the mixture, and the addition amount of the mineralizer is 0.02-0.03 wt% of the total weight of the mixture;

the heat stabilizer is one or a mixture of more than two of SIS resin, C5 petroleum resin or calcium carbonate; the polycarboxylic acid dispersing water reducing agent is one or a mixture of more than two of sodium gluconate, sodium dodecyl sulfate (K12) and alpha-sodium alkenyl sulfonate (AOS); the mineralizer is one or the mixture of more than two of yttrium oxide, cerium oxide or nitroglycerin.

2. The ultralow-wire-change baking-free air brick according to claim 1,characterized in that the sintered plate-like corundum particles are Al₂O₃The content of the high-density polyethylene is more than or equal to 98 weight percent, and the volume density is more than or equal to 3.55g/cm³The granularity is less than or equal to 8mm, the closed porosity is 10-20%, and the pore diameter is 3-10 um; said fine corundum powder, Al₂O₃The content of the inorganic nano-particles is more than or equal to 98wt percent, and the granularity is less than or equal to 0.088 mm.

3. The ultralow linear variation burn-free air brick as claimed in claim 1, wherein the alumina-rich spinel particles contain 20-26 wt% of MgO and Al₂O₃The content of (B) is 72-79 wt%, and the granularity is less than or equal to 8 mm; in the aluminum-rich spinel micro powder, the content of MgO is 20-26 wt%, and Al is₂O₃The content of (B) is 72-79 wt%, and the median diameter D50 is 5-20 um.

4. The ultralow-wire-change baking-free air brick as claimed in claim 1, wherein the activated α -alumina micropowder, Al₂O₃The content of the component (A) is more than or equal to 98wt%, and the median diameter D50 is 0.5-6 um.

5. The ultralow linear variation burn-free air brick as claimed in claim 1, wherein said green fine powder of chromium oxide, Cr₂O₃The content of the inorganic filler is more than or equal to 98wt percent, and the granularity is less than or equal to 0.044 mm.

6. The ultralow wire variation burn-free air brick as claimed in claim 1, wherein said zirconia fine powder, ZrO 2₂The content of the inorganic nano-particles is more than or equal to 90wt percent, and the granularity is less than or equal to 0.044 mm.

7. The ultralow linear variation burn-free air brick as claimed in claim 1, wherein said pure calcium aluminate cement and Al₂O₃68-71 wt% of CaO, 29-32 wt% of CaO, and the granularity is less than or equal to 0.044 mm.

8. The preparation method of the ultralow-linear-change baking-free air brick as claimed in claim 1, characterized by comprising the following steps:

1) preparing the proportioning stock of claim 1;

2) firstly, mixing corundum fine powder, aluminum-rich spinel fine powder, pure calcium aluminate cement, zirconia fine powder, active alpha-alumina fine powder, polycarboxylic acid dispersing water reducer and chromium oxide green fine powder in a premixer for 3-5 minutes to obtain premixed powder for later use;

3) taking a heat stabilizer and a mineralizer, adding water accounting for 3-4% of the total weight of the heat stabilizer and the mineralizer, and uniformly stirring for later use;

4) putting the sintered tabular corundum particles and the aluminum-rich spinel particles into a mixer, adding the premixed powder obtained in the step 2), dry-mixing for 1-3 minutes, finally adding the mixture obtained in the step 3), and uniformly wet-mixing for 3-8 minutes to obtain a castable;

5) adding the casting material obtained in the step 4) into a mold, carrying out vibration molding, and maintaining for 12-48 hours at the temperature of 20-100 ℃ to obtain a blank;

6) demolding the blank formed in the step 5), and maintaining for 72-240 hours at the temperature of 20-100 ℃ to obtain a sample;

7) and (3) carrying out heat treatment on the sample obtained in the step 6) at the temperature of 450-800 ℃ for 12-48 hours to obtain the ultralow linear change baking-free air brick.

9. The use of the ultralow linear change unfired air brick of claim 1 in refining ladle air bricks.