Roasting and charging method for improving performance uniformity of isostatic pressing graphite product

Abstract

The invention discloses a roasting and charging method for improving the performance uniformity of an isostatic pressing graphite product, and belongs to the technical field of graphite production. Comprising the following steps: S1, laying first metallurgical coke at the bottom of a steel drum; s2, loading the green body on the top of metallurgical coke; s3, petroleum coke is poured between the green body and the inner wall of the steel drum till the petroleum coke is flush with the top wall of the green body; s4, pouring a second kind of metallurgical coke above the green body until the opening of the steel drum is flush; s5, roasting the steel drum in the step S4; wherein the granularity of the first metallurgical coke is greater than that of the second metallurgical coke. The second metallurgical coke has a capillary effect and has an adsorption effect on steam generated by the liquid asphalt, so that the sinking resistance of the liquid asphalt due to the gravity effect is larger; the first kind of metallurgical coke ensures that sinking asphalt discharges volatile components through a smooth channel to reduce coking, so that the coking value is artificially reduced, the inconsistency of volume density can be bidirectionally reduced by increasing the upper coking value of the product and reducing the lower coking value of the product, and the performance uniformity of the product is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of graphite production, in particular to a roasting and charging method for improving the performance uniformity of isostatic graphite products. Background Art

[0002] Isostatic graphite is a high-performance specialty graphite material with electrical conductivity, high strength, high thermal conductivity and high uniformity. These properties make isostatic graphite an important material in the semiconductor industry.

[0003] The production of isostatic graphite is relatively complex, generally involving 6 processes, namely grinding, kneading, molding, impregnation, roasting and graphitization. Each process plays an important role and jointly determines the uniform performance of the final product. Among them, the process that has a greater impact on the uniform performance of the product is the roasting process. For this reason, domestic manufacturers have adopted a variety of methods to reduce the impact of roasting on the uniformity of product performance, such as controlling the temperature difference in the roasting furnace to make it as low as possible to reduce the impact of temperature on performance; extending the roasting curve to make the product performance more superior to make up for the poor performance of some weak parts; using pressurized roasting to increase the residual carbon rate of asphalt, thereby essentially improving product performance.

[0004] Although the above-mentioned prior art has improved the uniform performance of the product to a certain extent, the overall effect is not particularly ideal. Generally speaking, the main reason for the inconsistent performance of the product during the roasting process is that the asphalt will flow down under the influence of gravity after liquefaction, resulting in different coking degrees in various parts of the product, mainly in the height direction of the product, so how to reduce the influence of gravity is the key. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a roasting and charging method for improving the performance uniformity of isostatic graphite products, by adjusting the type, particle size and filling sequence of the filler, the negative impact of roasting on the consistency of product performance can be effectively reduced with a relatively small cost investment.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A roasting and charging method for improving the performance uniformity of isostatic graphite products comprises the following steps:

[0008] S1. Laying the first metallurgical coke on the bottom of the steel drum;

[0009] S2. placing the green body on top of the first metallurgical coke;

[0010] S3. Pour petroleum coke between the green billet and the inner wall of the steel drum until the petroleum coke is flush with the top wall of the green billet;

[0011] S4. Pour the second metallurgical coke on top of the green billet until the mouth of the steel barrel is flush;

[0012] S5. The steel drum in S4 is roasted;

[0013] Among them, the particle size of the first metallurgical coke is larger than the particle size of the second metallurgical coke.

[0014] As one possible embodiment of the present application, the particle size of the first metallurgical coke is 6-20 mesh.

[0015] As one possible embodiment of the present application, in step S1, the laying thickness of the first metallurgical coke is 200-320 mm.

[0016] As one possible embodiment of the present application, in step S1, the laying thickness of the first type of metallurgical coke is 300 mm.

[0017] As one of the embodiments of the present application, the particle size of the petroleum coke is 30-60 mesh; the moisture content of the petroleum coke is less than 0.1%.

[0018] As one of the possible embodiments of the present application, the particle size of the second metallurgical coke is 80-150 mesh.

[0019] As one possible embodiment of the present application, in step S4, the laying thickness of the second metallurgical coke is 330-450 mm.

[0020] As one possible embodiment of the present application, in step S4, the laying thickness of the second metallurgical coke is 350 mm.

[0021] As one possible embodiment of the present application, the specification of the green body is D600*600mm or D600*1000mm.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention starts from a deep-level principle analysis, and improves and optimizes the barreling process of the roasting process (in the prior art, the steel barrel is filled with the same type of fillers with the same upper, middle and lower particle sizes), such as the type and particle size of the fillers and the loading order of the fillers, to improve the performance uniformity of the roasted blank at a lower cost and maximize the consistency of the performance of the final finished product. Specifically, the second type of metallurgical coke with a smaller upper particle size has a capillary effect, which has an adsorption effect on the steam generated by the liquid asphalt, making the resistance of the liquid asphalt to sink due to the gravity effect greater; the first type of metallurgical coke with a larger lower particle size ensures that the sinking asphalt discharges the volatile matter through a smooth channel without participating in coking, thereby artificially reducing the coking value. The present application can increase the coking value of the upper part of the product and reduce the coking value of the lower part of the product by gradually increasing the particle size of the fillers in the steel barrel from top to bottom, and can close the inconsistency of "low on top and high on bottom" of the body density (body density is related to the coking value, the higher the coking value, the higher the body density). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 :Schematic diagram of green billet barreling

[0025] Figure 2 : Body density test sampling diagram;

[0026] Among them, 1-steel drum; 2-first type metallurgical coke; 3-green billet; 4-petroleum coke; 5-second type metallurgical coke. DETAILED DESCRIPTION

[0027] Roasting refers to a single roasting process, which is the process of carbonizing the binder into binder coke by heat treatment (about 1000℃) of the green body. That is, the pressed green body is placed in a roasting furnace, isolated from the air for heating, and the binder undergoes a series of physical and chemical reactions at a certain temperature to form a binder coke film of a certain thickness on the surface of the carbon aggregate. The binder coke connects the carbon powder particles to form a whole with certain mechanical strength and physical and chemical properties. At the same time, the roasting process is the first checkpoint to test the quality of the green body. The roasting quality (qualified rate and roasted body performance) also determines the production cost and the performance of the final product. Therefore, roasting is crucial for the entire graphite production. Therefore, domestic and foreign manufacturers attach great importance to the research on roasting technology. For example, from the initial large-scale use of ring furnaces to roast isostatic graphite to now almost all roasting in car bottom furnaces, especially for high-end graphite products. This is related to the fact that car bottom furnaces have better temperature control capabilities and can minimize the defects of inconsistent product performance caused by temperature differences. In addition, some manufacturers have also adopted the method of pressure roasting in order to compensate for the substandard performance of some locations by improving the overall performance.

[0028] Generally speaking, the main reason why the roasting process leads to inconsistent product performance is that the asphalt will flow downward under the influence of gravity after liquefaction, resulting in different degrees of coking in different parts of the product, mainly differences in the height direction of the product, so how to reduce the influence of gravity is the key.

[0029] Based on this, the present application provides a roasting and charging method for improving the performance uniformity of isostatic graphite products, comprising the following steps:

[0030] S1 lays the first type of metallurgical coke on the bottom of the steel drum;

[0031] S2 loads the green body on top of the first metallurgical coke;

[0032] S3: Pour petroleum coke between the green billet and the inner wall of the steel drum until the petroleum coke is flush with the top wall of the green billet;

[0033] S4 pours the second metallurgical coke on top of the green billet until the mouth of the steel barrel is flush;

[0034] S5 roasts the steel barrel in S4;

[0035] Among them, the particle size of the first metallurgical coke is larger than the particle size of the second metallurgical coke.

[0036] The present application effectively reduces the negative impact of roasting on the consistency of product performance with a relatively small cost investment by adjusting the type and filling order of the filler; specifically, the second type of metallurgical coke with a smaller particle size in the upper layer has a capillary effect, and has an adsorption effect on the vapor generated by the liquid asphalt, making the liquid asphalt have a greater resistance to sinking due to the gravity effect; the first type of metallurgical coke with a larger particle size in the lower layer ensures that the sinking asphalt discharges the volatile matter through a smooth channel without participating in coking, thereby artificially reducing the coking value. The present application can close the inconsistency of the "low on top and high on bottom" of the bulk density (the bulk density is related to the coking value, the higher the coking value, the higher the bulk density) in both directions by increasing the coking value of the upper part of the product and reducing the coking value of the lower part of the product, thereby effectively improving the uniform performance of the product.

[0037] In order to effectively improve the uniform performance of the product, as one of the embodiments of the present application, the specifications of the first metallurgical coke are further limited, that is, the specifications of the first metallurgical coke are 6-20 mesh.

[0038] In order to effectively improve the uniform performance of the product, as one of the embodiments of the present application, the laying thickness of the first metallurgical coke is further limited, that is, in step S1, the laying thickness of the first metallurgical coke is 200-320mm, and more preferably, the laying thickness of the first metallurgical coke is 300mm.

[0039] In order to effectively improve the uniform performance of the product, as one of the embodiments of the present application, the laying thickness of the petroleum coke is further limited, that is, the specification of the petroleum coke is 30-60 mesh; the moisture content of the petroleum coke is less than 0.1%.

[0040] In order to effectively improve the uniform performance of the product, as one of the possible embodiments of the present application, the laying thickness of the second metallurgical coke is further limited, that is, the specification of the second metallurgical coke is 80-150 mesh.

[0041] In order to effectively improve the uniform performance of the product, as one of the embodiments of the present application, the laying thickness of the second metallurgical coke is further limited, that is, in step S4, the laying thickness of the second metallurgical coke is 330-450mm, and more preferably, the laying thickness of the second metallurgical coke is 50mm.

[0042] In order to effectively improve the uniform performance of the product, as one of the possible embodiments of the present application, the specifications of the green body are further limited, that is, the specifications of the green body are D600*600mm or D600*1000mm.

[0043] Next, the barrel filling and roasting process of the present invention are described in detail.

[0044] Example 1

[0045] S1 Figure 1 As shown, the first metallurgical coke 2 with a specification of 6-20 mesh is laid on the bottom of the steel drum 1 with a thickness of about 300 mm;

[0046] S2 puts the green billet 3 of D600*600mm into the barrel and places it in the center as much as possible;

[0047] S3 pours petroleum coke 4 with a specification of 30-60 mesh into the steel barrel 1 until the upper edge of the green body 3 is flush;

[0048] S4 is poured again with the second type of metallurgical coke 4 with a specification of 80-150 mesh until the barrel mouth is flush, and the thickness of the upper layer is about 350mm;

[0049] S5 is placed in a car bottom type roasting furnace (existing technology) until roasting is completed.

[0050] Example 2

[0051] S1 Figure 1 As shown, the first metallurgical coke 2 with a specification of 6-20 mesh is laid on the bottom of the steel drum 1 with a thickness of about 300 mm;

[0052] S2 puts the green body 3 of D600*1000mm into the barrel and places it in the center as much as possible;

[0053] S3 pours petroleum coke 4 with a specification of 30-60 mesh into the steel barrel 1 until the upper edge of the green body 3 is flush;

[0054] S4 is poured again with the second type of metallurgical coke 4 with a specification of 80-150 mesh until the barrel mouth is flush, and the thickness of the upper layer is about 350mm;

[0055] S5 is placed in a car bottom type roasting furnace (existing technology) until roasting is completed.

[0056] Comparative Example

[0057] The conventional method is adopted to fill the barrel, that is, the same type of petroleum coke with the same upper, middle and lower particle sizes is fully loaded in the steel barrel. In this comparative example, the steel barrel is fully loaded with 30-60 mesh petroleum coke.

[0058] Experimental example

[0059] After sintering, the bulk density is used as a reference object, and the specific positions of the green body after sintering, that is, the points farthest apart in the height direction (such as Figure 1 The six positions (1, 1-1, 2, 2-1, 3, and 3-1) in the sample test are used to indicate the maximum performance difference. The sample marks are as follows: Figure 2 As shown, 1 and 1-1 are two points on the same vertical direction, 2 and 2-1 are two points on the same vertical direction, and 3 and 3-1 are two points on the same vertical direction.

[0060] The specific data of body density test are shown in Table 1-Table 3.

[0061] The green body density data of the green body obtained by calcining using the barrel filling method of Comparative Example 1 (i.e., the steel barrel is filled with the same type of fillers with the same upper, middle and lower particle sizes) are shown in Table 1.

[0062] Table 1

[0063]

[0064]

[0065] The density data of the green embryos obtained by barreling in Example 1 and Example 2 are shown in Table 2.

[0066] Table 2

[0067]

[0068] Table 3 shows the comparison of the bulk density difference between the green bodies obtained by barreling in Example 1-2 (after optimization) and Comparative Example 1 (before optimization), i.e. before and after optimization.

[0069] Table 3

[0070]

[0071] The difference value in Table 3 = [(larger volume density data in the same vertical direction - smaller volume density data) / smaller volume density data] × 100%.

[0072] It can be seen from Table 3 that after optimizing the D600*600mm green billet, the difference in bulk density can be reduced from more than 3.4% before optimization to less than 2%, and after optimizing the D600*1000mm green billet, the difference in bulk density can be reduced from more than 4.4% before optimization to less than 2.5%, which significantly improves the uniformity of the product. This shows that the present application has successfully achieved an improvement in the uniformity of the product.

[0073] It can be seen from Table 3 that the larger the product height, the greater the difference in volume density, and the better the optimization effect.

Claims

1. A roasting and charging method for improving the performance uniformity of isostatic graphite products, characterized in that: The steps include: S1. Laying the first metallurgical coke (2) on the bottom of the steel drum (1); S2. The green body (3) is mounted on top of the first metallurgical coke (2); S3. Pour petroleum coke (4) between the green body (3) and the inner wall of the steel drum (1) until the petroleum coke (4) is flush with the top wall of the green body (3); S4. Pour the second metallurgical coke (5) onto the green body (3) until the mouth of the steel drum (1) is flush; S5. The steel drum (1) in S4 is roasted; The particle size of the first metallurgical coke (2) is greater than the particle size of the second metallurgical coke (5).

2. A roasting and charging method for improving the performance uniformity of isostatic graphite products according to claim 1, characterized in that: The particle size of the first metallurgical coke (2) is 6-20 mesh.

3. A roasting and charging method for improving the performance uniformity of isostatic graphite products according to claim 1, characterized in that: In step S1, the laying thickness of the first metallurgical coke (2) is 200-320 mm.

4. A roasting and charging method for improving the performance uniformity of isostatic graphite products according to claim 3, characterized in that: In step S1, the laying thickness of the first type of metallurgical coke (2) is 300 mm.

5. A roasting and charging method for improving the performance uniformity of isostatic graphite products according to claim 1, characterized in that: The particle size of the petroleum coke (4) is 30-60 meshes; the moisture content of the petroleum coke (4) is less than 0.1%.

6. A roasting and charging method for improving the performance uniformity of isostatic graphite products according to claim 1, characterized in that: The second metallurgical coke (5) has a particle size of 80-150 mesh.

7. A roasting and charging method for improving the performance uniformity of isostatic graphite products according to claim 1, characterized in that: In step S4, the laying thickness of the second metallurgical coke (5) is 330-450 mm.

8. A roasting and charging method for improving the performance uniformity of isostatic graphite products according to claim 7, characterized in that: In step S4, the laying thickness of the second type of metallurgical coke (5) is 350 mm.

9. A roasting and charging method for improving the performance uniformity of isostatic graphite products according to claim 1, characterized in that: The specification of the green body (3) is D600*600mm or D600*1000mm.

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