A mullite flow steel brick made from raw alumina powder and its preparation method

Abstract

This invention discloses a mullite flow steel brick made from raw bauxite powder and its preparation method. The mullite flow steel brick comprises the following raw materials by weight percentage: 40-60% bauxite particles with an Al2O3 content of 75-85%; 15-30% raw bauxite fine powder with an Al2O3 content of 69-71%; 5-10% calcined bauxite fine powder with an Al2O3 content of 75-85%; and 10-2% raw clay fine powder with an Al2O3 content of 25-35%. 5%; This type of mullite flow steel brick does not use expensive mullite as raw material, but instead uses inexpensive raw alumina fine powder. By controlling the amount of each raw material, it produces mullite flow steel bricks with a porosity of 19-25%, compressive strength of 60-120 MPa, and refractoriness greater than 1800℃ at low cost. All indicators are higher than the national industry standard "YB / T4637-2018 Mullite Flow Steel Bricks", which greatly reduces the production cost of mullite flow steel bricks.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically relating to a mullite flow steel brick made from raw alumina powder and its preparation method. Background Technology

[0002] Mullite bricks possess high refractoriness and good thermal shock resistance, making them an ideal material for producing mullite flow steel bricks. Mullite flow steel bricks are primarily used as functional refractory materials for flowing molten steel during the casting and smelting of special steels. Because special steels have high molten steel temperatures and contain various alloying materials, the molten steel intensifies the erosion and scouring of the refractory materials. Therefore, flow steel bricks are required to have even better resistance to erosion and scouring.

[0003] Mullite flow bars are resistant to erosion and scouring by molten steel, reducing the entry of refractory particles into the molten steel and ensuring its purity, thereby improving the quality of special steels. Currently, most flow bars used in special steel die casting production are made from mullite, with selective use of andalusite, white corundum powder, etc., as raw materials. These raw materials are expensive, resulting in high production costs.

[0004] For example, Chinese patent CN106747519 A discloses a non-stick steel flow brick and its preparation method, specifically disclosing the following raw materials by weight: 3-5 parts mullite with a particle size of 3-0 mm, 1-2 parts andalusite with a particle size of 1-0 mm, 0.5-2 parts white corundum powder with a particle size of 320 mesh, 1-2 parts andalusite powder with a particle size of 200 mesh, 1-2 parts calcined kaolin powder with a particle size of 200 mesh, and 0.5-1.5 parts Guangxi white clay powder with a particle size of 200 mesh. The specific preparation method involves steps such as batching, molding, firing, and sorting and packaging. Although the non-stick steel flow brick prepared by the method disclosed in this patent has strong erosion resistance, good thermal shock performance, does not stick to steel slag or molten steel, and does not contaminate molten steel, this patent uses a large amount of expensive mullite, andalusite, and white corundum powder, and the raw material composition is complex, resulting in high production costs.

[0005] Chinese Patent CN 113135764 A discloses a mullite flow steel brick and its preparation method, specifically disclosing that the mullite flow steel brick is made of the following components in corresponding weight percentages: 30% bauxite aggregate, 22% mullite powder, 32% mullite aggregate, 15% clay, and 1% dehydrating agent. Although the mullite flow steel brick disclosed in this patent has a simple composition, it requires a large amount of mullite as powder and aggregate, resulting in high production costs and a low product qualification rate.

[0006] Chinese patent CN 115490505 A discloses an anti-erosion mullite flow steel brick and its preparation method. The components, by mass percentage, are: 15-20% 3-1mm high-purity sintered mullite, 30-35% 0-1mm high-purity sintered mullite, 3-5% 3-1m white corundum, 20-25% 200-325 mesh South African andalusite powder, 12.5-17.5% alumina micropowder below 5μm, 5-7% Guangxi clay, and 2.8-3.5% binder. This patent uses a large amount of mullite, white corundum, and South African andalusite powder as raw materials, resulting in high production costs. Summary of the Invention

[0007] To solve the above-mentioned technical problems, this invention provides a mullite flow steel brick made from raw alumina powder and its preparation method. This mullite flow steel brick does not use expensive mullite as a raw material, but instead uses inexpensive raw alumina powder to replace mullite powder. By controlling the amount of each raw material, a mullite flow steel brick with a porosity of 19-25%, compressive strength of 60-120 MPa, and refractoriness greater than 1800℃ is produced at low cost. All indicators are higher than the requirements of the national industry standard "YB / T4637-2018 Mullite Flow Steel Brick". The mullite phase of this mullite flow steel brick reaches more than 81%.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] This invention provides a mullite flow steel brick made from raw alumina powder, wherein the mullite flow steel brick comprises the following raw materials by weight percentage:

[0010]

[0011]

[0012] The raw alumina powder contains 69-71% Al2O3, 27-29% SiO2, and less than 1% Fe2O3. After calcination, the above-mentioned mixture containing this raw alumina powder can achieve a mullite phase content of over 81%.

[0013] Furthermore, the mullite flow steel brick preferably comprises the following raw materials by weight percentage:

[0014]

[0015] Furthermore, the mullite flow steel brick preferably comprises the following raw materials by weight percentage:

[0016]

[0017] Furthermore, the mullite flow steel brick preferably comprises the following raw materials by weight percentage:

[0018]

[0019] The alumina particles with an Al2O3 content of 75-85% have a particle size of 1-3 mm.

[0020] The particle size of the raw alumina powder is 180-220 mesh.

[0021] The fine powder of calcined alumina with an Al2O3 content of 75-85% has a particle size of 180-220 mesh.

[0022] The fine powder of raw clay with an Al2O3 content of 25-35% has a particle size of 170-190 mesh.

[0023] The present invention also provides a method for manufacturing mullite flow steel bricks using raw alumina powder, the method comprising the following steps:

[0024] (1) Mix the raw materials of the mullite flow steel brick made of raw alumina powder as described in this invention to obtain a mixed powder;

[0025] (2) Add lignin liquid and water to the mixed powder, stir and mix evenly to make mud;

[0026] (3) Add the clay into the mold and press it into shape;

[0027] (4) Dry the semi-finished product after molding;

[0028] (5) The dried semi-finished product is sintered at high temperature to obtain mullite flow steel bricks.

[0029] Furthermore, in step (2), the mass ratio of the mixed powder, lignin liquid, and water is 94–97:1.5–3.0:1.5–3.0, preferably 95:2.5:2.5. The lignin liquid has a certain binding property, and adding lignin liquid when preparing the mud can improve the formability of the semi-finished product.

[0030] In step (5), the sintering temperature is 1350-1370℃ and the sintering time is 10-12h.

[0031] The mullite flow steel bricks made from raw alumina powder provided by this invention innovatively use raw alumina fine powder as a raw material. The raw alumina fine powder can be used without aging, thus reducing the cost. In addition, it is combined with raw clay fine powder, and the amount of raw powder in the whole formula can reach up to 55%, which greatly reduces the production cost.

[0032] The applicant discovered in practice that as long as raw alumina fine powder with an Al2O3 content of 69-71%, a SiO2 content of about 27-29%, and an Fe2O3 content of less than 1% is used as raw material, and the amount of raw alumina fine powder is controlled at 15-30%, and combined with alumina granules, calcined alumina fine powder, and raw clay fine powder as raw materials, mullite flow bricks with a porosity of 19-25%, a compressive strength of 60-120 MPa, and a refractoriness greater than 1800℃ can be prepared, all of which are higher than the requirements of the national industry standard "YB / T4637-2018 Mullite Flow Bricks".

[0033] If the amount of raw bauxite exceeds 30%, to ensure the overall Al2O3 content of the product, the amount of raw clay powder with a lower Al2O3 content must be reduced, since the bound clay only contains 30% Al2O3. This results in a higher sintering temperature and increased energy consumption during the preparation of mullite flow steel bricks. This is because raw bauxite powder is more difficult to sinter than raw clay powder, and an increase in the amount of raw bauxite powder inevitably leads to a higher sintering temperature. Conversely, if the amount of raw bauxite is less than 15%, other clinker is needed to ensure the overall Al2O3 content of the product, thus failing to achieve the goals of cost reduction and energy consumption reduction.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1) This invention uses raw bauxite fine powder with an Al2O3 content of 69-71%, a SiO2 content of about 27-29%, and an Fe2O3 content of less than 1% to produce mullite flow steel bricks, which effectively replaces the use of calcined mullite powder, thereby reducing the energy consumption of primary sintering of mullite ore and contributing to emission reduction and energy conservation.

[0036] 2) The amount of raw alumina fine powder used in this invention is 15-30%. The use of raw alumina fine powder improves the molding performance of the clay to a certain extent, which is beneficial to the molding of steel bricks.

[0037] 3) The mullite flow steel bricks provided by this invention have a porosity of 19-25%, a compressive strength of 60-120 MPa, and a refractoriness of over 1800℃. All of these indicators are higher than the national industry standard "YB / T4637-2018 Mullite Flow Steel Bricks".

[0038] 4) In the mullite flow steel bricks provided by the present invention, by adjusting the Al2O3 content in each raw material, mullite flow steel bricks with different Al2O3 contents that meet the needs of different customers can be produced.

[0039] 5) In the mullite flow steel bricks provided by this invention, raw alumina fine powder is used instead of cooked mullite powder, which greatly reduces production costs and improves enterprise efficiency. Detailed Implementation

[0040] The present invention will now be described in detail with reference to the embodiments.

[0041] Unless otherwise specified, all contents mentioned in this invention are percentages by mass.

[0042] The particle size of the bauxite particles in each embodiment and comparative example is 1-3 mm; the particle size of the raw bauxite fine powder and the cooked bauxite fine powder is 200 mesh; and the particle size of the raw clay fine powder is 180 mesh.

[0043] The lignin liquid, model SQRS-1, was purchased from Jinan Shengquan Group Co., Ltd.

[0044] Example 1

[0045] A mullite flow steel brick made from raw alumina powder, with the following weight percentages of each raw material:

[0046] 58% of the bauxite particles have an Al2O3 content of 80%;

[0047] 22% raw alumina fine powder with Al2O3 content of 69%, SiO2 content of 28%, and Fe2O3 content of less than 1%;

[0048] 8% fine powder of calcined bauxite with an Al2O3 content of 80%;

[0049] 12% raw clay powder with an Al2O3 content of 30%.

[0050] The preparation method of the mullite flow steel brick includes the following steps:

[0051] (1) Mix the above raw materials to obtain a mixed powder;

[0052] (2) Add lignin liquid and water to the mixed powder. The mass ratio of the mixed powder to the lignin liquid and water is 95:2.5:2.5. Stir and mix evenly to make a mud.

[0053] (3) Add the clay into the mold and press it into shape;

[0054] (4) Dry the semi-finished product after molding;

[0055] (5) The dried semi-finished product was sintered at 1355℃ for 11 hours to obtain mullite flow steel bricks with a mullite phase content of 83%.

[0056] Example 2

[0057] A mullite flow steel brick made from raw alumina powder, with the following weight percentages of each raw material:

[0058] 50% of the bauxite particles have an Al2O3 content of 80%;

[0059] 25% raw alumina fine powder with Al2O3 content of 69%, SiO2 content of 28%, and Fe2O3 content of less than 1%;

[0060] 10% fine powder of calcined bauxite with an Al2O3 content of 80%;

[0061] 15% raw clay powder with an Al2O3 content of 30%.

[0062] The preparation method of the mullite flow steel brick includes the following steps:

[0063] (1) Mix the above raw materials to obtain a mixed powder;

[0064] (2) Add lignin liquid and water to the mixed powder. The mass ratio of the mixed powder to the lignin liquid and water is 95:2.5:2.5. Stir and mix evenly to make a mud.

[0065] (3) Add the clay into the mold and press it into shape;

[0066] (4) Dry the semi-finished product after molding;

[0067] (5) The dried semi-finished product was sintered at 1370℃ for 10h to obtain mullite flow steel bricks with a mullite phase of 81%.

[0068] Example 3

[0069] A mullite flow steel brick made from raw alumina powder, with the following weight percentages of each raw material:

[0070] 48% of the bauxite particles have an Al2O3 content of 80%;

[0071] 22% raw alumina fine powder with Al2O3 content of 69%, SiO2 content of 28%, and Fe2O3 content of less than 1%;

[0072] 8% of finely powdered bauxite with an Al2O3 content of 75-85%;

[0073] 22% raw clay powder with an Al2O3 content of 30%.

[0074] The preparation method of the mullite flow steel brick includes the following steps:

[0075] (1) Mix the above raw materials to obtain a mixed powder;

[0076] (2) Add lignin liquid and water to the mixed powder. The mass ratio of the mixed powder to the lignin liquid and water is 95:2.5:2.5. Stir and mix evenly to make a mud.

[0077] (3) Add the clay into the mold and press it into shape;

[0078] (4) Dry the semi-finished product after molding;

[0079] (5) The dried semi-finished product was sintered at 1360℃ for 10 hours to obtain mullite flow steel bricks with a mullite phase of 84%.

[0080] Comparative Example 1

[0081] A type of mullite flow steel brick, the weight percentages of its raw materials are as follows:

[0082] 58% of the bauxite particles have an Al2O3 content of 80%;

[0083] 23% fine powder of calcined bauxite with an Al2O3 content of 80%;

[0084] Raw clay powder with an Al2O3 content of 30% and a fine content of 19%.

[0085] The preparation method of the mullite flow steel brick includes the following steps:

[0086] (1) Mix the above raw materials to obtain a mixed powder;

[0087] (2) Add water to the mixed powder at a solid-liquid ratio of 95:5 and stir to mix evenly to make mud;

[0088] (3) Add the clay into the mold and press it into shape;

[0089] (4) Dry the semi-finished product after molding;

[0090] (5) The dried semi-finished product was sintered at 1360℃ for 10 hours to obtain mullite flow steel bricks with a mullite phase of 55%.

[0091] Comparative Example 2

[0092] A type of mullite flow steel brick, the weight percentages of its raw materials are as follows:

[0093] 50% of the bauxite particles have an Al2O3 content of 80%;

[0094] 24% fine powder of calcined bauxite with an Al2O3 content of 80%;

[0095] Raw clay powder with an Al2O3 content of 30% and 26%.

[0096] The preparation method of the mullite flow steel brick includes the following steps:

[0097] (1) Mix the above raw materials to obtain a mixed powder;

[0098] (2) Add water to the mixed powder at a solid-liquid ratio of 95:5 and stir to mix evenly to make mud;

[0099] (3) Add the clay into the mold and press it into shape;

[0100] (4) Dry the semi-finished product after molding;

[0101] (5) The dried semi-finished product was sintered at 1370℃ for 10 hours to obtain mullite flow steel bricks with a mullite phase of 60%.

[0102] Comparative Example 3

[0103] A type of mullite flow steel brick, the weight percentages of its raw materials are as follows:

[0104] 48% of the bauxite particles have an Al2O3 content of 80%;

[0105] 20% fine powder of calcined bauxite with an Al2O3 content of 75-85%;

[0106] 32% raw clay powder with an Al2O3 content of 30%.

[0107] The preparation method of the mullite flow steel brick includes the following steps:

[0108] (1) Mix the above raw materials to obtain a mixed powder;

[0109] (2) Add water to the mixed powder at a solid-liquid ratio of 95:5 and stir to mix evenly to make mud;

[0110] (3) Add the clay into the mold and press it into shape;

[0111] (4) Dry the semi-finished product after molding;

[0112] (5) The dried semi-finished product was sintered at 1360℃ for 13h to obtain mullite flow steel bricks with a mullite phase of 65%.

[0113] Comparative Example 4

[0114] A mullite flow steel brick made from raw alumina powder, with the following weight percentages of each raw material:

[0115] 50% of the bauxite particles have an Al2O3 content of 80%;

[0116] 35% raw alumina fine powder with Al2O3 content of 69%, SiO2 content of 28%, and Fe2O3 content of less than 1%;

[0117] 10% fine powder of calcined bauxite with an Al2O3 content of 80%;

[0118] 5% raw clay powder with an Al2O3 content of 30%.

[0119] The preparation method of the mullite flow steel brick includes the following steps:

[0120] (1) Mix the above raw materials to obtain a mixed powder;

[0121] (2) Add lignin liquid and water to the mixed powder. The mass ratio of the mixed powder to the lignin liquid and water is 95:2.5:2.5. Stir and mix evenly to make a mud.

[0122] (3) Add the clay into the mold and press it into shape;

[0123] (4) Dry the semi-finished product after molding;

[0124] (5) The dried semi-finished product was sintered at 1400℃ for 13 hours to obtain mullite flow steel bricks with a mullite phase of 83%.

[0125] Comparative Example 5

[0126] A mullite flow steel brick made from raw alumina powder, with the following weight percentages of each raw material:

[0127] 58% of the bauxite particles have an Al2O3 content of 80%;

[0128] 22% raw alumina fine powder with Al2O3 content of 50%, SiO2 content of 45%, and Fe2O3 content of 2%;

[0129] 8% fine powder of calcined bauxite with an Al2O3 content of 80%;

[0130] 12% raw clay powder with an Al2O3 content of 30%.

[0131] The preparation method of the mullite flow steel brick includes the following steps:

[0132] (1) Mix the above raw materials to obtain a mixed powder;

[0133] (2) Add lignin liquid and water to the mixed powder. The mass ratio of the mixed powder to the lignin liquid and water is 95:2.5:2.5. Stir and mix evenly to make a mud.

[0134] (3) Add the clay into the mold and press it into shape;

[0135] (4) Dry the semi-finished product after molding;

[0136] (5) The dried semi-finished product is sintered at 1360℃ and kept at 10h to obtain mullite flow steel bricks with a mullite phase of 45%.

[0137] The properties of the mullite flow steel bricks prepared in the above embodiments and comparative examples are shown in Table 1.

[0138] Table 1

[0139]

[0140] In Table 1, porosity and bulk density were tested according to GB / T 2997-2015; compressive strength was tested according to GB / T5072-2008; Al2O3 content and Fe2O3 content were tested according to GB / T 21114-2019; refractoriness was tested according to GB / T 7322-2017; and permanent linearization upon heating was tested according to GB / T 5988-2007.

[0141] As can be seen from the above, the technical solution provided by the present invention can produce mullite flow bricks with a porosity of 19-25%, a compressive strength of 60-120 MPa, and a refractoriness greater than 1800℃. All of these indicators are higher than the requirements of the national industry standard "YB / T4637-2018 Mullite Flow Bricks".

[0142] The above detailed description of a mullite flow steel brick made from raw alumina powder and its preparation method is illustrative rather than limiting. Several embodiments can be listed within the defined scope. Therefore, variations and modifications without departing from the overall concept of the present invention should be within the protection scope of the present invention.

Claims

1. A mullite flow steel brick made from raw alumina powder, characterized in that, The mullite flow steel brick comprises the following raw materials by weight percentage: Alumina particles with an Al2O3 content of 75-85% and a content of 40-60%; 15-30% raw alumina fine powder; Fine powder of calcined bauxite with an Al2O3 content of 75-85% and 5-10%; 10-25% fine powder of raw clay with an Al2O3 content of 25-35%; The raw alumina powder contains 69-71% Al2O3, 27-29% SiO2, and less than 1% Fe2O3.

2. The mullite flow steel brick made from raw alumina powder according to claim 1, characterized in that, The mullite flow steel brick comprises the following raw materials by weight percentage: Alumina particles with an Al2O3 content of 75-85% and an Al2O3 content of 55-60%; 20-30% raw alumina powder; Fine powder of calcined bauxite with an Al2O3 content of 75-85% and 5-10%; 10-15% fine powder of raw clay with an Al2O3 content of 25-35%.

3. The mullite flow steel brick made from raw alumina powder according to claim 1, characterized in that, The mullite flow steel brick comprises the following raw materials by weight percentage: Alumina particles with an Al2O3 content of 75-85% and an Al2O3 content of 45-55%; 15-25% raw alumina powder; Fine powder of calcined bauxite with an Al2O3 content of 75-85%; Raw clay powder with an Al2O3 content of 25-35% and a fine content of 15-25%.

4. The mullite flow steel brick made from raw alumina powder according to claim 1, characterized in that, The mullite flow steel brick comprises the following raw materials by weight percentage: Alumina particles with an Al2O3 content of 75-85% and a content of 40-50%; 15-25% raw alumina powder; Fine powder of calcined bauxite with an Al2O3 content of 75-85%; Raw clay powder with an Al2O3 content of 25-35% and a fine content of 15-25%.

5. The mullite flow steel brick made from raw alumina powder according to claim 1, characterized in that, The alumina particles with an Al2O3 content of 75-85% have a particle size of 1-3 mm.

6. The mullite flow steel brick made from raw alumina powder according to claim 1, characterized in that, The particle size of the raw alumina powder is 180-220 mesh.

7. The mullite flow steel brick made from raw alumina powder according to claim 1, characterized in that, The fine powder of calcined alumina with an Al2O3 content of 75-85% has a particle size of 180-220 mesh.

8. The mullite flow steel brick made from raw alumina powder according to claim 1, characterized in that, The fine powder of raw clay with an Al2O3 content of 25-35% has a particle size of 170-190 mesh.

9. A method for manufacturing mullite flow steel bricks using raw alumina powder, characterized in that, The method includes the following steps: (1) Mix the raw materials of the mullite flow steel brick made of raw alumina powder as described in any one of claims 1-8 to obtain a mixed powder; (2) Add lignin liquid and water to the mixed powder, stir and mix evenly to make mud; (3) Add the clay into the mold and press it into shape; (4) Dry the semi-finished product after molding; (5) The dried semi-finished product is sintered at high temperature to obtain mullite flow steel bricks.

10. The method according to claim 9, characterized in that, In step (5), the sintering temperature is 1350-1370℃ and the sintering time is 10-12h.

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