Refractory brick for carbon roasting furnace and preparation method thereof

Abstract

The present invention belongs to the technical field of refractory materials, and specifically relates to a refractory brick for a carbon roasting furnace and a preparation method thereof. The refractory brick for a carbon roasting furnace provided by the present invention comprises large particles of bauxite clinker, large particles of mullite, medium particles of bauxite clinker, additive powder, alumina powder, and a binder; the additive powder is composed of andalusite powder, silica powder and corundum powder in a mass ratio of 4-8:13-17:11-15. In the present invention, andalusite, silica and corundum are used to form additives together, which effectively improves the high temperature performance of refractory bricks for carbon roasting furnaces; forsterite, ferric oxide and magnesium oxide are added to the formula, which effectively improves the density and bonding strength of refractory bricks for carbon roasting furnaces. The refractory bricks for a carbon roasting furnace provided by the present invention have low apparent porosity, low high temperature creep rate, high load softening temperature, stable high temperature volume, good thermal stability and long service life.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory materials, and in particular relates to a refractory brick for a carbon roasting furnace and a preparation method thereof. Background Art

[0002] The function of the carbon roasting furnace is to heat the various carbon blocks formed by high pressure at the specified roasting temperature in isolation from air, so as to improve the mechanical strength, electrical conductivity and temperature resistance of carbon products. The bottom and pit surface of the kiln structure of the carbon roasting furnace, as well as the fire channel wall, bear the weight of the upper brick body and roasted products, the high temperature of the upper electrode box heating wall and other parts for a long time at high temperature, and the influence of temperature changes during the roasting cycle. Therefore, the refractory bricks used for the roasting furnace fire channel wall must be built with refractory materials with high mechanical strength, low high temperature creep rate, high load softening temperature and good thermal stability.

[0003] At present, the refractory bricks used in domestic carbon roasting furnaces are mainly Al 2 O 3 -SiO 2 It is mainly a refractory product. During the roasting process, a large amount of alkali metals K and Na from the anode carbon block are converted into Al 2 O 3 -SiO 2 The refractory absorbs and reacts with the components of the refractory to form new expansion phases of potassium nepheline (containing potassium) and nepheline (containing sodium). Both of these new expansion phases will cause damage to the refractory structure, thereby accelerating the failure of the refractory bricks in the roasting furnace. 2 O 3 -SiO 2 The thermal conductivity of refractory bricks is relatively large. They are in an expanded state before 1000℃, and begin to shrink after 1000℃. The bricks will creep at around 1200℃, causing the fire channel wall to deform, thereby reducing the service life of the carbon roasting furnace.

[0004] A Chinese patent application document with publication number CN117865657A discloses a refractory brick for the flue wall of a carbon roasting furnace, the formula of which includes a granular material composed of talc particles and one or two of low-alumina bauxite clinker particles, coke clinker particles or waste brick particles after carbon furnace use, and a powder material composed of high-alumina raw material fine powder, talc fine powder, corundum dust collection powder, plastic clay fine powder or / and silicon micropowder. This refractory brick solves the technical problem of high manufacturing cost of refractory bricks for carbon roasting furnaces and has good high-temperature performance, but its apparent porosity and high-temperature load softening temperature are less improved than those of existing roasting furnace refractory bricks.

[0005] A Chinese patent application document with publication number CN106187239A discloses a low-creep pyroxene composite refractory brick, whose formula includes super-large pyroxene particles, large pyroxene particles, small pyroxene particles, small sillimanite particles, pyroxene micropowder, combined with clay fine powder and additives. This refractory brick has good thermal shock resistance and a high load softening temperature, but its thermal stability is poor. Summary of the invention

[0006] In order to solve the technical problem of poor high temperature performance of refractory bricks existing in the related art, the object of the present invention is to provide a refractory brick for a carbon roasting furnace and a preparation method thereof.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] A refractory brick for a carbon roasting furnace comprises the following components and their weight proportions:

[0009] 10-15 parts of large bauxite clinker particles, 10-20 parts of large mullite particles, 30-40 parts of medium bauxite clinker particles, 20-25 parts of additive powder, 10-15 parts of alumina powder, and 15-20 parts of binder;

[0010] The additive powder is composed of andalusite powder, silica powder and corundum powder in a mass ratio of 4-8:13-17:11-15.

[0011] In the present invention, andalusite, silica and corundum are used to form additives, which effectively improves the high temperature performance of refractory bricks for carbon roasting furnaces. Wherein andalusite can be converted into a network mullite and a silicon-rich glass phase with capillary pores at high temperature, a part of the silicon-rich glass phase is filled in the capillary pores of the network mullite, and the other part is squeezed to the crystal surface, which can effectively fill the pores in the refractory bricks and reduce the apparent porosity. At the same time, in the process of mullitization, the silicon-rich glass phase can not only heal the cracks of the refractory bricks, but also stop the microcracks in the liquid phase, thereby improving the high temperature pressure resistance of the refractory bricks; however, the higher the content of the silicon-rich glass phase, the higher the high temperature creep rate of the refractory bricks, so it is necessary to control the amount of andalusite. Corundum has good high temperature compressive strength and volume stability, high load softening temperature, good chemical corrosion resistance, and will react with silica to mullite at high temperature to form an interlaced mullite network structure, which crosses in the matrix, effectively improving the high temperature load softening temperature and compressive strength of the refractory bricks.

[0012] The inventors found during the research that when the amount of silica added is small, the Al 2 O 3 The mullite reaction at the particle boundary is strong, and the mullite reaction in the matrix is ​​relatively weak. The refractory bricks produced are not well sintered and have poor high temperature performance. When the amount of silica added is large, the SiO2 Excess, and excess SiO 2 It will be converted into cristobalite, and the volume expansion of the refractory bricks will increase, the porosity will increase, and the high temperature performance will deteriorate. When the amount of andalusite, silica and corundum added is within the range of the present invention, the Al in the matrix 2 O 3 The mullite reaction at the particle boundary is weakened, the mullite reaction in the matrix is ​​relatively enhanced, and the sintering performance of the refractory brick is improved.

[0013] Furthermore, the refractory bricks for the carbon roasting furnace include the following components and their weight proportions: 12 parts of large bauxite clinker particles, 16 parts of large mullite particles, 35 parts of medium bauxite clinker particles, 24 parts of additive powder, 13 parts of alumina powder, and 18 parts of binder; the additive powder is composed of andalusite powder, silica powder and corundum powder in a mass ratio of 7:14:13.

[0014] Furthermore, the particle size of the large particles of bauxite clinker and mullite is 3-5 mm; the particle size of the particles in the bauxite clinker is 1-3 mm; and the particle size of the additive powder and alumina powder is 0.01-0.10 mm.

[0015] Furthermore, the binder is one or more of aluminum dihydrogen phosphate, ammonium phosphate, sodium hexametaphosphate and sodium tripolyphosphate.

[0016] Furthermore, the refractory bricks for the carbon roasting furnace also include the following components and their weight proportions: 10-15 parts of forsterite, 5-10 parts of ferric oxide, and 5-10 parts of magnesium oxide.

[0017] In the present invention, forsterite, ferric oxide and magnesium oxide are added to the refractory bricks for carbon roasting furnaces. Forsterite can be evenly dispersed in the refractory bricks in the form of a precursor to improve the density of the refractory bricks. 2 O 3 And ferric oxide can form magnesia-ferrocene spinel and magnesia-alumina spinel with magnesium oxide, which are evenly dispersed at the boundaries of refractory bricks to improve the bonding strength of refractory bricks.

[0018] Furthermore, the particle size of the forsterite is 200-300nm, the particle size of the ferric oxide is 400-500nm, and the particle size of the magnesium oxide is 300-400nm.

[0019] The present invention also provides a method for preparing the refractory bricks for the carbon roasting furnace, comprising the following steps:

[0020] S1: mixing large bauxite clinker particles, large mullite particles, medium bauxite clinker particles, additive powder and alumina powder to obtain primary powder;

[0021] S2: Mix the binder and water evenly to obtain a binder aqueous solution; add the primary powder, forsterite, ferric oxide and magnesium oxide obtained in step S1, stir well to obtain a mud blank;

[0022] S3: Pressing the clay obtained in step S2 into a shape to obtain a rough brick, drying, heating, sintering, and cooling to obtain a refractory brick.

[0023] Furthermore, the mass percentage of the binder aqueous solution in step S2 of the method for preparing refractory bricks for carbon roasting furnace is 17%-20%.

[0024] Furthermore, in step S3 of the method for preparing refractory bricks for carbon roasting furnace, the drying temperature is 65-70°C, the heating rate is 10-15°C / h, the sintering temperature is 1450-1650°C, the sintering time is 24-28h, and the cooling rate is 30-50°C / h.

[0025] Compared with the prior art, the refractory bricks for carbon roasting furnace and the preparation method thereof provided by the present invention have the following technical advantages:

[0026] (1) The present invention uses andalusite, silica and corundum to form an additive, which effectively improves the high temperature performance of refractory bricks for carbon roasting furnaces;

[0027] (2) In the present invention, forsterite, ferric oxide and magnesium oxide are added to the refractory bricks for the carbon roasting furnace, which effectively improves the density and bonding strength of the refractory bricks for the carbon roasting furnace;

[0028] (3) The refractory bricks for carbon roasting furnace provided by the present invention have low apparent porosity, low high-temperature creep rate, high load softening temperature, stable high-temperature volume, good thermal stability and long service life. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. Those skilled in the art can make various modifications based on the basic idea of ​​the present invention, but as long as they do not deviate from the basic idea of ​​the present invention, they are all within the scope of the present invention.

[0030] Example 1

[0031] A refractory brick for a carbon roasting furnace comprises the following components and their weight proportions:

[0032] 10 parts of large particles of bauxite clinker with a particle size of 3mm, 20 parts of large particles of mullite with a particle size of 3mm, 30 parts of medium particles of bauxite clinker with a particle size of 1mm, 20 parts of additive powder with a particle size of 0.01mm, 10 parts of alumina powder with a particle size of 0.01mm, 15 parts of aluminum dihydrogen phosphate, 10 parts of forsterite with a particle size of 200nm, 5 parts of ferric oxide with a particle size of 400nm, and 5 parts of magnesium oxide with a particle size of 300nm; the additive powder is composed of andalusite powder, silica powder and corundum powder in a mass ratio of 4:13:11.

[0033] The method for preparing refractory bricks for carbon roasting furnace comprises the following steps:

[0034] S1: mixing large bauxite clinker particles, large mullite particles, medium bauxite clinker particles, additive powder and alumina powder to obtain primary powder;

[0035] S2: mixing aluminum dihydrogen phosphate and water evenly to obtain a binder aqueous solution with a mass percentage of 17%; adding the primary powder, forsterite, ferric oxide and magnesium oxide obtained in step S1, stirring well to obtain a mud blank;

[0036] S3: Press the clay obtained in step S2 into a rough brick, dry it at 65°C, heat it to 1450°C at a rate of 10°C / h, sinter it for 28h, and cool it at a cooling rate of 30°C / h to obtain a refractory brick.

[0037] Example 2

[0038] A refractory brick for a carbon roasting furnace comprises the following components and their weight proportions:

[0039] 15 parts of large bauxite clinker particles with a particle size of 5 mm, 10 parts of large mullite particles with a particle size of 5 mm, 40 parts of medium bauxite clinker particles with a particle size of 3 mm, 25 parts of additive powder with a particle size of 0.10 mm, 15 parts of alumina powder with a particle size of 0.10 mm, 20 parts of sodium hexametaphosphate, 15 parts of forsterite with a particle size of 300 nm, 10 parts of ferric oxide with a particle size of 500 nm, and 10 parts of magnesium oxide with a particle size of 400 nm; the additive powder is composed of andalusite powder, silica powder and corundum powder in a mass ratio of 8:17:15.

[0040] The method for preparing refractory bricks for carbon roasting furnace comprises the following steps:

[0041] S1: mixing large bauxite clinker particles, large mullite particles, medium bauxite clinker particles, additive powder and alumina powder to obtain primary powder;

[0042] S2: Evenly mix sodium hexametaphosphate and water to obtain a binder aqueous solution with a mass percentage of 20%; add the primary powder, forsterite, ferric oxide and magnesium oxide obtained in step S1, and stir well to obtain a mud blank;

[0043] S3: Press the clay obtained in step S2 into a rough brick, dry it at 70°C, heat it to 1650°C at a rate of 15°C / h, sinter it for 24h, and cool it at a cooling rate of 50°C / h to obtain a refractory brick.

[0044] Example 3

[0045] A refractory brick for a carbon roasting furnace comprises the following components and their weight proportions:

[0046] 12 parts of large bauxite clinker particles with a particle size of 4 mm, 16 parts of large mullite particles with a particle size of 4 mm, 35 parts of medium bauxite clinker particles with a particle size of 2 mm, 24 parts of additive powder with a particle size of 0.08 mm, 13 parts of alumina powder with a particle size of 0.06 mm, 18 parts of sodium tripolyphosphate, 13 parts of forsterite with a particle size of 275 nm, 8 parts of ferric oxide with a particle size of 445 nm, and 8 parts of magnesium oxide with a particle size of 350 nm; the additive powder is composed of andalusite powder, silica powder and corundum powder in a mass ratio of 7:14:13.

[0047] The method for preparing refractory bricks for carbon roasting furnace comprises the following steps:

[0048] S1: mixing large bauxite clinker particles, large mullite particles, medium bauxite clinker particles, additive powder and alumina powder to obtain primary powder;

[0049] S2: Evenly mix sodium tripolyphosphate and water to obtain a binder aqueous solution with a mass percentage of 18%; add the primary powder, forsterite, ferric oxide and magnesium oxide obtained in step S1, and stir well to obtain a mud blank;

[0050] S3: Press the clay obtained in step S2 into a rough brick, dry it at 68°C, heat it to 1520°C at a rate of 13°C / h, sinter it for 26h, and cool it at a cooling rate of 42°C / h to obtain a refractory brick.

[0051] Comparative Example 1

[0052] The formula and preparation method of the refractory bricks for the carbon roasting furnace described in this comparative example are similar to those of Example 3. The difference between this comparative example and Example 3 is that the additive powder described in this comparative example is composed of andalusite powder, silica powder and corundum powder in a mass ratio of 17:2:5.

[0053] Comparative Example 2

[0054] The formula and preparation method of the refractory bricks for the carbon roasting furnace described in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that the additive powder in this comparative example is composed of andalusite powder, silica powder and corundum powder in a mass ratio of 3:18:13.

[0055] Comparative Example 3

[0056] The refractory bricks for carbon roasting furnace and the preparation method described in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that an equal amount of silica powder is used instead of andalusite powder in this comparative example.

[0057] Comparative Example 4

[0058] The refractory bricks for carbon roasting furnace and the preparation method described in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that an equal amount of andalusite powder is used instead of corundum powder in this comparative example.

[0059] Comparative Example 5

[0060] The refractory bricks for carbon roasting furnace and the preparation method described in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that an equal amount of corundum powder is used instead of forsterite powder in this comparative example.

[0061] Comparative Example 6

[0062] The refractory bricks for carbon roasting furnace and the preparation method described in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that an equal amount of forsterite powder is used to replace ferric oxide in this comparative example.

[0063] Comparative Example 7

[0064] The refractory bricks for carbon roasting furnace and the preparation method described in this comparative example are similar to those in Example 3. The difference between this comparative example and Example 3 is that this comparative example uses an equal amount of forsterite powder instead of magnesium oxide.

[0065] Test example

[0066] Test samples: refractory bricks prepared in Examples 1 to 3 and Comparative Examples 1 to 7;

[0067] Test method: According to GB / T 2997-2015, the bulk density and apparent porosity of the test samples are tested; according to YB / T370-2016, the refractoriness under load of the test samples is tested; according to GB / T 5073-2022, the high temperature creep rate (1280°C, 25h) of the test samples is tested; according to GB / T 5072-2008, the room temperature compressive strength of the test samples is tested; according to GB / T 7320-2018, the thermal expansion rate of the test samples is tested; (the qualified indicators of refractory brick products are: high temperature creep rate 1280°C×25h≤0.45%, high temperature refractoriness under load ≥1450°C, apparent porosity ≤19MPa, room temperature compressive strength ≥50MPa).

[0068] Test results: The test results are shown in Table 1.

[0069] Table 1 Performance test results

[0070]

[0071] As shown in Table 1, the bulk density of the refractory bricks for carbon roasting furnace provided by the present invention is 2.55-2.83 g / cm 3 , the apparent porosity is 11%-14%, the thermal expansion rate is 0.52%-0.70%, the load softening temperature is 1680-1735℃, the high temperature creep rate is 0.01%-0.04%, and the room temperature compressive strength is greater than 62MPa, which fully demonstrates that the refractory bricks for carbon roasting furnaces provided by the present invention have good high temperature performance. Among them, the refractory bricks prepared in Example 3 have the best performance in all aspects and are the best embodiment of the present invention.

[0072] Compared with Example 3, Comparative Examples 1 and 2 change the dosage ratio of each component of the additive. In Comparative Example 1, the dosage of silica is reduced, but the thermal expansion rate and high-temperature creep rate of the refractory bricks obtained are increased, and the load softening temperature is reduced. In Comparative Example 2, the dosage of silica is increased, but the bulk density, load softening temperature, and room-temperature compressive strength of the refractory bricks obtained are reduced, and the apparent porosity, thermal expansion rate, and high-temperature creep rate are increased, which indicates that the addition of silica will affect the high-temperature performance of the refractory bricks. An increase in the dosage of andalusite will lead to an increase in the content of silicon-rich glass phase in the high-temperature refractory bricks, resulting in an increase in the high-temperature creep rate; Comparative Example 3 uses an equal amount of silica powder instead of andalusite powder, but the bulk density and room-temperature compressive strength of the refractory bricks obtained are reduced, and the apparent porosity and high-temperature creep rate are increased, which indicates that andalusite can reduce the apparent porosity of refractory bricks. Improve the bulk density and compressive strength; Example 4 uses an equal amount of andalusite powder instead of corundum powder, but the load softening temperature of the refractory brick obtained is reduced, the high-temperature creep rate is increased, and the normal pressure compressive strength is reduced, which shows that corundum powder can improve the normal pressure compressive strength and volume stability of the refractory brick, and the increase in the amount of andalusite powder will lead to a decrease in the load softening temperature of the refractory brick and an increase in the high-temperature creep rate; Example 5 uses an equal amount of corundum powder instead of forsterite powder, but the bulk density of the refractory brick is reduced, which shows that forsterite can improve the density of the refractory brick; Example 6 uses an equal amount of forsterite powder instead of ferric oxide, and Example 7 uses an equal amount of forsterite powder instead of magnesium oxide, but the normal pressure compressive strength of the refractory brick obtained is reduced, which shows that the addition of ferric oxide and magnesium oxide can improve the compressive strength of the refractory brick.

[0073] The above embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any person skilled in the art shall not modify the above embodiments without violating the spirit and scope of the present invention. Therefore, any modification, equivalent substitution and improvement made by those skilled in the art under the technical concept of the present invention shall still be covered by the claims of the present invention.

Claims

1. A refractory brick for a carbon roasting furnace, characterized in that: It includes the following components and their weight parts: 10-15 parts of large particles of bauxite clinker, 10-20 parts of large particles of mullite, 30-40 parts of medium particles of bauxite clinker, 20-25 parts of additive powder, 10-15 parts of alumina powder, 15-20 parts of binder, 10-15 parts of forsterite, 5-10 parts of ferric oxide, and 5-10 parts of magnesium oxide; the additive powder is composed of andalusite powder, silica powder and corundum powder in a mass ratio of 4-8:13-17:11-15.

2. The refractory brick for carbon roasting furnace according to claim 1, characterized in that: The invention comprises the following components and their weight proportions: 12 parts of large particles of bauxite clinker, 16 parts of large particles of mullite, 35 parts of medium particles of bauxite clinker, 24 parts of additive powder, 13 parts of alumina powder, 18 parts of binder, 13 parts of forsterite, 8 parts of ferric oxide and 8 parts of magnesium oxide; the additive powder is composed of andalusite powder, silica powder and corundum powder in a mass ratio of 7:14:

13.

3. The refractory brick for carbon roasting furnace according to claim 1 or 2, characterized in that: The particle sizes of the large particles of bauxite clinker and mullite are 3-5 mm; the particle sizes of the particles in the bauxite clinker are 1-3 mm; and the particle sizes of the additive powder and alumina powder are 0.01-0.10 mm.

4. The refractory brick for carbon roasting furnace according to claim 1 or 2, characterized in that: The binder is one or more of aluminum dihydrogen phosphate, ammonium phosphate, sodium hexametaphosphate and sodium tripolyphosphate.

5. The refractory brick for carbon roasting furnace according to claim 1, characterized in that: The particle size of the forsterite is 200-300nm, the particle size of the ferric oxide is 400-500nm, and the particle size of the magnesium oxide is 300-400nm.

6. The method for preparing refractory bricks for carbon roasting furnace according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: mixing large bauxite clinker particles, large mullite particles, medium bauxite clinker particles, additive powder and alumina powder to obtain primary powder; S2: Mix the binder and water evenly to obtain a binder aqueous solution; add the primary powder, forsterite, ferric oxide and magnesium oxide obtained in step S1, stir well to obtain a mud blank; S3: Pressing the clay obtained in step S2 into a shape to obtain a rough brick, drying, heating, sintering, and cooling to obtain a refractory brick.

7. The method for preparing refractory bricks for carbon roasting furnace according to claim 6, characterized in that: The mass percentage of the binder aqueous solution in step S2 is 17%-20%.

8. The method for preparing refractory bricks for carbon roasting furnace according to claim 6, characterized in that: In step S3, the drying temperature is 65-70°C, the heating rate is 10-15°C / h, the sintering temperature is 1450-1650°C, the sintering time is 24-28h, and the cooling rate is 30-50°C / h.

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