High-temperature melting furnace for preparing high-alpha-phase spherical aluminum oxide and method for preparing high-alpha-phase spherical aluminum oxide

Abstract

The invention provides a high-temperature melting furnace for preparing high-alpha-phase spherical aluminum oxide and a method for preparing the high-alpha-phase spherical aluminum oxide, and relates to the technical field of inorganic material preparation. The high-temperature melting furnace for preparing the high-alpha-phase spherical aluminum oxide comprises a melting zone and a cooling zone which are arranged from top to bottom, and a separation layer is arranged between the melting zone and the cooling zone; the partition layer comprises a cross beam supporting body and a support structure connected to the cross beam supporting body in a lap joint mode. The support structure comprises a plurality of stacked support layers, each support layer is composed of prisms which are arranged in parallel at intervals, the prisms of the adjacent support layers are arranged in a criss-cross mode, and the longitudinal cutting sections of the prisms in each support layer are the same in shape and are in an upright triangle shape or an upright trapezoid shape. According to the invention, the high-temperature melting furnace is transformed, and the partition is additionally arranged above the cooling zone, so that the descending of materials can be stopped, the descending speed of the materials can be delayed, and the retention time of spherical aluminum oxide in a high-temperature section can be prolonged, thereby obtaining a high-alpha-phase spherical aluminum oxide product.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic material preparation, in particular to a high-temperature melting furnace for preparing high-alpha phase spherical alumina and a method for preparing high-alpha phase spherical alumina. Background Art

[0002] The application performance of alumina in many fields is closely related to the morphology of powder particles. Among powder particles of different shapes, spherical particles have regular morphology, smaller specific surface area, larger packing density and better flow properties, which can greatly improve the application performance of products. With the rapid development of science and technology, higher requirements are also put forward for electronic products. Improving the thermal conductivity of fillers used in electronic packaging materials is one of the most important directions. Spherical alumina is one of the important high thermal conductivity and high filling fillers.

[0003] The flame melting method is currently the most advanced process for producing spherical alumina powder, and the main equipment used is a high-temperature melting furnace. However, the spherical alumina obtained by the existing high-temperature melting furnace has a low a-phase content, resulting in low thermal conductivity, which limits its application in the electronics field. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a high-temperature melting furnace for preparing high-α-phase spherical alumina and a method for preparing high-α-phase spherical alumina. The high-temperature melting furnace provided by the present invention can prepare high-α-phase spherical alumina.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a high-temperature melting furnace for preparing high-alpha phase spherical alumina, comprising a melting zone and a cooling zone arranged from top to bottom, wherein a partition layer is arranged between the melting zone and the cooling zone;

[0007] The partition layer includes a crossbeam support body and a bracket structure overlapped on the crossbeam support body;

[0008] The support structure includes a plurality of stacked support layers, each support layer is composed of prisms arranged in parallel and spaced apart, the prisms of adjacent support layers are arranged in a crisscross pattern, and the longitudinal cross-section of the prisms in each support layer has the same shape, which is a right triangle or a right trapezoid.

[0009] Preferably, the total number of the support layers is 3.

[0010] Preferably, the height of the prisms in each support layer is 200-300 mm, and the interval is 240-360 mm.

[0011] Preferably, the two base angles of the regular triangle and the regular trapezoid are 60°.

[0012] Preferably, the crossbeam support body is made of high-temperature heat-resistant steel, and the prisms in the support layer are made of alumina refractory material.

[0013] The present invention provides a method for preparing high-alpha phase spherical alumina in a high-temperature melting furnace as described in the above technical solution, comprising the following steps:

[0014] The alumina powder raw material is carried by a carrier gas into the melting zone of the high-temperature melting furnace, and is melted under the action of a high-temperature flame in the melting zone to form alumina molten particles; the a-phase content of the alumina powder raw material is greater than 98%, and the temperature of the high-temperature flame is 2700-2800°C;

[0015] The alumina solution descends, passes through the isolation layer and enters the cooling zone to be cooled, thereby obtaining high-α-phase spherical alumina.

[0016] Preferably, the alumina powder raw material includes one or more of angular alumina, quasi-spherical alumina and white corundum.

[0017] Preferably, the average particle size of the alumina powder raw material is 90-180 μm; and the alumina content of the alumina powder raw material is above 99.7%.

[0018] Preferably, the high temperature flame is formed by the combustion of fuel and combustion-supporting gas, the fuel is natural gas, and the combustion-supporting gas is oxygen; in terms of volume ratio, the ratio of the fuel to the combustion-supporting gas is 1.05 to 1.25.

[0019] Preferably, the carrier gas is oxygen, and the flow rate of the carrier gas is 150-290 m 3 / h, the concentration of the aluminum oxide powder raw material in the carrier gas is 0.1-60 kg / m 3 .

[0020] The present invention provides a high-temperature melting furnace for preparing high-alpha phase spherical alumina, comprising a melting zone and a cooling zone arranged from top to bottom, a partition layer is arranged between the melting zone and the cooling zone; the partition layer comprises a crossbeam support body and a support structure overlapped on the crossbeam support body; the support structure comprises a plurality of stacked support layers, each support layer is composed of prisms arranged in parallel and spaced relation, the prisms of adjacent support layers are arranged in a crisscross pattern, and the longitudinal cross-section of the prisms in each support layer is the same in shape, which is a right triangle or a right trapezoid. The present invention remodels the interior of the high-temperature melting furnace and adds a partition layer above the cooling zone, which can block the descent of the material, slow down the descent speed of the material, and increase the residence time of the spherical alumina in the high-temperature section, thereby obtaining a high-alpha phase spherical alumina product, the average alpha content of which is ≥90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1It is a schematic diagram of the overall structure of the high temperature melting furnace in the embodiment;

[0022] Figure 2 This is the placement effect of the beam support body in the high-temperature melting furnace in the embodiment;

[0023] Figure 3 This is the placement effect of the beam support body in the high-temperature melting furnace in the embodiment;

[0024] Figure 4 This is a schematic diagram of the water inlet and outlet in the supporting beam;

[0025] Figure 5 This is an overall effect diagram of the partition layer in the embodiment;

[0026] Figure 6 This is the placement effect diagram of the lowest support layer;

[0027] Figure 7 This is the layout effect diagram of the middle support layer;

[0028] Figure 8 This is the layout effect diagram of the top support layer. DETAILED DESCRIPTION

[0029] The present invention provides a high-temperature melting furnace for preparing high-alpha phase spherical alumina, comprising a melting zone and a cooling zone arranged from top to bottom, wherein a partition layer is arranged between the melting zone and the cooling zone;

[0030] The partition layer includes a crossbeam support body and a bracket structure overlapped on the crossbeam support body;

[0031] The support structure includes a plurality of stacked support layers, each support layer is composed of prisms arranged in parallel and spaced apart, the prisms of adjacent support layers are arranged in a crisscross pattern, and the longitudinal cross-section of the prisms in each support layer has the same shape, which is a right triangle or a right trapezoid.

[0032] The overall structure of the high temperature melting furnace in the embodiment of the present invention is as follows Figure 1 As shown, the detailed description is given below.

[0033] The high-temperature melting furnace provided by the present invention comprises a melting zone and a cooling zone arranged from top to bottom. The present invention has no special requirements on the structural arrangement of the melting zone and the cooling zone, and the high-temperature melting furnace structural arrangement well known to those skilled in the art can be adopted.

[0034] In the present invention, a partition layer is arranged between the melting zone and the cooling zone, and the partition layer comprises a crossbeam support body and a support structure overlapped on the crossbeam support body.

[0035] In the embodiment of the present invention, the beam support body is preferably composed of a two-layer beam structure, wherein the lower beam structure is preferably a supporting beam, and the upper beam structure is preferably two supporting beams spaced and arranged in parallel, the supporting beams in the lower beam structure preferably penetrate the radial direction of the melting zone, the supporting beams in the upper beam structure are preferably symmetrical relative to the axis of the melting zone, and the supporting beams in the lower beam structure and the supporting beams in the upper beam structure are preferably arranged vertically and horizontally. In the embodiment of the present invention, the placement effect of the beam support body in the high-temperature melting furnace is as follows: Figure 2 and Figure 3 shown.

[0036] In the present invention, the support beam in the beam support body is preferably a hollow structure, and the longitudinal section is preferably a square. The hollow structure in the support beam is used for water inlet and outlet, which cools the support beam and prolongs the service life of the support beam. In the present invention, the material of the beam support body is high temperature heat-resistant steel, and more preferably heat-resistant stainless steel. Figure 4 Schematic diagram of water inlet and outlet in the supporting beam.

[0037] In the present invention, the support structure includes a plurality of stacked support layers, each support layer is composed of parallel spaced prisms, the prisms of adjacent support layers are arranged in a crisscross pattern, and the longitudinal cross-section of the prisms in each support layer is the same shape, which is a right triangle or a right trapezoid (i.e., the upper base length of the trapezoid is less than the lower base length). In an embodiment of the present invention, the total number of support layers is preferably 3, wherein the longitudinal cross-section of the prisms in the top support layer is preferably a right triangle, and the longitudinal cross-section of the prisms in the remaining two support layers is preferably a right trapezoid, Figure 5 This is an overall effect diagram of the partition layer composed of two layers of beam structures and three layers of support layers in an embodiment of the present invention. Figure 6 to Figure 8The following are the layout effect diagrams of the bottom support layer, the middle support layer and the top support layer. In the present invention, the height of the prism in each support layer is preferably 200-300 mm. When the longitudinal section of the prism in the support layer is a right triangle, the height of the prism (i.e., the height of the right triangle) is preferably 300 mm. When the longitudinal section of the prism in the support layer is a right trapezoid, the height of the prism (i.e., the height of the right trapezoid) is preferably 200 mm. In the present invention, the two base angles of the right triangle and the right trapezoid are preferably 60°, and the lengths of the lower base sides of the right triangle and the right trapezoid are preferably equal. In the present invention, the spacing of the prisms in each support layer (the horizontal distance of the free area between adjacent prisms) is preferably 240-360 mm, and the number of prisms in each support layer is based on the internal dimensions of the adapted molten zone. In the present invention, the material of the prisms in the support layer is preferably alumina refractory material, and the refractoriness is preferably greater than 1500°C, and can be cast with alumina castables. The present invention provides a plurality of support layers arranged in a criss-cross pattern, which can block the descent of materials, slow down the descent speed of materials, increase the high-temperature insulation time of materials, and thus increase the content of α-phase spherical alumina; the longitudinal cross-section shape of the prism is set to a right triangle or a right trapezoid, which can prevent the materials from falling and staying on the support during the descent process.

[0038] In the present invention, an expansion joint is preferably provided between the fusion zone and the isolation layer. The present invention has no special requirements on the structural setting of the expansion joint, and a conventional expansion joint setting method can be adopted.

[0039] The present invention provides a method for preparing high-alpha phase spherical alumina in a high-temperature melting furnace as described in the above technical solution, comprising the following steps:

[0040] The alumina powder raw material is carried by a carrier gas into the melting zone of the high-temperature melting furnace, and is melted under the action of a high-temperature flame in the melting zone to form alumina molten particles; the a-phase content of the alumina powder raw material is greater than 98%, and the temperature of the high-temperature flame is 2700-2800°C;

[0041] The alumina solution descends, passes through the isolation layer and enters the cooling zone to be cooled, thereby obtaining high-α-phase spherical alumina.

[0042] In the present invention, the a-phase content of the alumina powder raw material is greater than 98%. In the present invention, the alumina powder raw material preferably includes one or more of angular alumina, quasi-spherical alumina and white corundum; the average particle size of the alumina powder raw material is preferably 90 to 180 μm, and the particle size of the alumina powder raw material is controlled to obtain spherical alumina with a large particle size; the alumina content of the alumina powder raw material is preferably above 99.7%.

[0043] In the present invention, the temperature of the high temperature flame is 2700-2800°C; the high temperature flame is preferably formed by the combustion of fuel and combustion-supporting gas, the fuel is preferably natural gas, and the combustion-supporting gas is preferably oxygen; in terms of volume ratio, the ratio of the fuel to the combustion-supporting gas is preferably 1.05-1.25. In the present invention, the carrier gas is preferably oxygen, and the flow rate of the carrier gas is preferably 150-290 m / s. 3 / h, more preferably 260 to 290 m / h 3 / h, the concentration of the alumina powder raw material in the carrier gas is preferably 0.1-60 kg / m 3 , more preferably 20 to 35 kg / m 3 The carrier gas has a dispersing effect on the aluminum oxide powder. In the present invention, the temperature of the cooling zone is preferably below 1100°C.

[0044] In the present invention, the alumina powder raw material passes through a high-temperature flame and is rapidly melted to form a spherical droplet-shaped melt, which then descends from a molten zone through an isolation layer into a cooling zone for cooling and condenses into balls, wherein the isolation layer increases the residence time of the spherical alumina in the high-temperature section and can increase the content of α-phase spherical alumina.

[0045] The invention prepares large-particle-size high-alpha-phase spherical alumina by transforming a high-temperature melting furnace, has low equipment transformation cost, simple installation and operation, and the obtained spherical alumina has a high alpha-phase content.

[0046] In order to further illustrate the present invention, the high temperature melting furnace for preparing high α-phase spherical alumina and the method for preparing high α-phase spherical alumina provided by the present invention are described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present invention.

[0047] Each embodiment adopts a modified high-temperature melting furnace, and its overall structure is as follows: Figure 1 As shown, from top to bottom, it includes a melting zone, a partition layer (there is an expansion joint between the melting zone and the partition layer) and a cooling zone; the partition layer is composed of a beam support body and a bracket structure placed on the beam support body. The lower beam structure is a support beam that runs through the radial direction of the melting zone, and the upper beam structure is two support beams that are parallel, spaced and arranged side by side and symmetrical with respect to the axis of the melting zone, and the support beams in the lower beam structure and the support beams in the upper beam structure are arranged vertically and horizontally. Figure 2 and Figure 3 This is the placement effect of the beam support body in the high-temperature melting furnace; the supporting beams are all hollow heat-resistant stainless steel square steels, and the hollow part is used for water inlet and outlet. Figure 4The schematic diagram of the water inlet and outlet in the supporting beam. The support structure consists of three layers of crisscross support layers, each of which is composed of parallel and spaced prisms (alumina refractory materials). The longitudinal section of the prisms in the top support layer is a right triangle (two base angles are 60°), and the longitudinal section of the prisms in the remaining two support layers is a right trapezoid (two base angles are 60°). The length of the lower base of the right triangle and the right trapezoid is equal; the height of the prisms in the top support layer of the three support layers is 300mm, and the height of the prisms in the remaining two support layers is 200mm. The interval between prisms in each layer is 240mm. Figure 5 This is the overall effect diagram of the partition layer. Figure 6 to Figure 8 The following are the layout effects of the bottom support layer, the middle support layer and the top support layer.

[0048] Example 1

[0049] The angular α-alumina powder raw material with an average particle size of 90 μm (alumina content of 99.85wt%, α phase content of 99%) is put into the modified high-temperature melting furnace, and oxygen is used as the combustion-supporting gas and carrier gas, and natural gas is used as the fuel to form a high-temperature flame. The angular α-alumina powder raw material is carried by the carrier gas (oxygen) and put into the high-temperature flame. The powder passes through the high-temperature flame and melts rapidly. It enters the cooling zone through the isolation layer from the melting zone to be cooled, and a spherical alumina powder product with an average particle size of 90 μm is obtained; wherein the flow rate of the carrier gas is 260m 3 / h, the powder concentration of carrier gas is 30kg / m 3 , the ratio of fuel to oxygen (by volume ratio) is 1.12.

[0050] Comparative Example 1

[0051] The angular α-alumina raw material with an average particle size of 90 μm was put into the high-temperature melting furnace before the transformation (i.e. the isolation layer was omitted), and the rest was the same as in Example 1 to obtain a spherical alumina powder product with an average particle size of 90 μm.

[0052] Example 2

[0053] A spherical alumina raw material with an average particle size of 120 μm (alumina content of 99.7wt%, α phase content of 99%) is put into a modified high-temperature melting furnace, and oxygen is used as a combustion-supporting gas and a carrier gas, and natural gas is used as a fuel to form a high-temperature flame. The spherical α-alumina powder raw material is carried by the carrier gas (oxygen) and put into the high-temperature flame. The powder passes through the high-temperature flame and melts rapidly. It enters the cooling zone through the isolation layer from the melting zone to be cooled, and a spherical alumina powder product with an average particle size of 120 μm is obtained; wherein the flow rate of the carrier gas is 280m 3 / h, the powder concentration of carrier gas is 25kg / m 3 , the ratio of fuel to oxygen (by volume) is 1.10.

[0054] Comparative Example 2

[0055] A spherical alumina raw material with an average particle size of 120 μm (alumina content of 99.7wt%, α phase content of 99%) is put into a high-temperature melting furnace before the modification (i.e. the partition layer is omitted), and the rest is the same as in Example 2 to obtain a spherical alumina powder product with an average particle size of 120 μm.

[0056] Example 3

[0057] The white corundum raw material with an average particle size of 120 μm (alumina content of 99.8wt%, α phase content of 99%) is put into the modified high-temperature melting furnace, and oxygen is used as the combustion-supporting gas and carrier gas, and natural gas is used as the fuel to form a high-temperature flame. The white corundum raw material is carried by the carrier gas (oxygen) and put into the high-temperature flame. The powder passes through the high-temperature flame and melts rapidly. It enters the cooling zone through the isolation layer from the melting zone to be cooled, and a spherical alumina powder product with an average particle size of 120 μm is obtained; wherein the flow rate of the carrier gas is 290m 3 / h, the powder concentration of the carrier gas is 20kg / m 3 , the ratio of fuel to oxygen (by volume ratio) is 1.08.

[0058] Example 4

[0059] The angular α-alumina raw material with an average particle size of 150μm (alumina content of 99.85wt%, α phase content of 99%) is put into the modified high-temperature melting furnace, and oxygen is used as the combustion-supporting gas and carrier gas, and natural gas is used as the fuel to form a high-temperature flame. The angular α-alumina powder raw material is carried by the carrier gas (oxygen) and put into the high-temperature flame. The powder passes through the high-temperature flame and melts rapidly. It enters the cooling zone through the isolation layer from the melting zone to be cooled, and obtains a spherical alumina powder product with an average particle size of 150μm; wherein the flow rate of the carrier gas is 260m 3 / h, the powder concentration of the carrier gas is 35kg / m 3 , the ratio of fuel to oxygen (by volume) is 1.10.

[0060] Comparative Example 3

[0061] Angular α-alumina raw material with an average particle size of 150 μm (alumina content is 99.85wt%, α phase content is 99%) is put into a high-temperature melting furnace before modification (i.e. the partition layer is omitted), and the rest is the same as Example 4 to obtain a spherical alumina powder product with an average particle size of 150 μm.

[0062] The α-alumina content of the spherical alumina powder products prepared in the test examples and comparative examples was tested, and the thermal conductivity was tested in the composite powder. The composition of the composite powder was: spherical alumina prepared in the example or comparative example: 40 μm spherical alumina: 5 μm spherical alumina: 2 μm spherical alumina: zinc oxide = 45%: 15%: 20%: 15%: 5%. The test results are shown in Table 1.

[0063] Table 1 α-alumina content and thermal conductivity of spherical alumina powder products of examples and comparative examples

[0064] a-phase aluminum oxide, % Thermal conductivity w / mk Comparative Example 1 68 4.15 Example 1 85 4.27 Comparative Example 2 72 4.18 Example 2 89 4.30 Example 3 90 4.30 Comparative Example 3 74 4.20 Example 4 93 4.34

[0065] It can be seen from the above examples that the present invention prepares large-particle-size high-α-phase spherical alumina by modifying a high-temperature melting furnace.

[0066] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A high-temperature melting furnace for preparing high-α-phase spherical alumina, comprising a melting zone and a cooling zone arranged from top to bottom, characterized in that: A partition layer is provided between the melting zone and the cooling zone; The partition layer includes a crossbeam support body and a bracket structure overlapped on the crossbeam support body; The support structure includes a plurality of stacked support layers, each support layer is composed of prisms arranged in parallel and spaced apart, the prisms of adjacent support layers are arranged in a crisscross pattern, and the longitudinal cross-section of the prisms in each support layer has the same shape, which is a right triangle or a right trapezoid.

2. The high temperature melting furnace according to claim 1, characterized in that: The total number of the support layers is 3.

3. The high temperature melting furnace according to claim 1, characterized in that: The height of the prisms in each support layer is 200-300 mm, and the interval is 240-360 mm.

4. The high temperature melting furnace according to claim 1 or 3, characterized in that: The two base angles of the regular triangle and the regular trapezoid are 60°.

5. The high temperature melting furnace according to claim 1, characterized in that: The material of the beam support body is high temperature heat-resistant steel, and the material of the prisms in the support layer is alumina refractory material.

6. A method for preparing high α-phase spherical alumina using a high temperature melting furnace as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: The alumina powder raw material is carried by a carrier gas into the melting zone of the high-temperature melting furnace, and is melted under the action of a high-temperature flame in the melting zone to form alumina molten particles; the a-phase content of the alumina powder raw material is greater than 98%, and the temperature of the high-temperature flame is 2700-2800°C; The alumina solution descends, passes through the isolation layer and enters the cooling zone to be cooled, thereby obtaining high-α-phase spherical alumina.

7. The method according to claim 6, characterized in that The alumina powder raw material includes one or more of angular alumina, quasi-spherical alumina and white corundum.

8. The method according to claim 6 or 7, characterized in that: The average particle size of the aluminum oxide powder raw material is 90 to 180 μm; the aluminum oxide content of the aluminum oxide powder raw material is more than 99.7%.

9. The method according to claim 6, characterized in that The high temperature flame is formed by the combustion of fuel and combustion-supporting gas, wherein the fuel is natural gas and the combustion-supporting gas is oxygen; in terms of volume ratio, the ratio of the fuel to the combustion-supporting gas is 1.05 to 1.

25.

10. The method according to claim 6, characterized in that The carrier gas is oxygen, and the flow rate of the carrier gas is 150-290m 3 / h, the concentration of the aluminum oxide powder raw material in the carrier gas is 0.1-60 kg / m 3 .

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