Preparation method of large-size square graphite electrode

Abstract

The invention discloses a method for preparing a large-sized quartzite electrode, and relates to the technical field of graphite electrode preparation. The main purpose is to provide a method for producing a large-sized quartzite electrode with a short production cycle and low production cost. The main technical scheme of the invention is: a method for preparing a large-sized quartzite electrode, which comprises the following steps: subjecting petroleum coke to high-temperature calcination treatment under air-tight conditions to obtain calcined coke; crushing the calcined coke to form a granular mixture; mixing the granular mixture evenly; adding asphalt to the granular mixture to obtain a mixture, and heating and kneading; pushing the mixture into a mold, vibrating and forming, and after demolding, placing the green body into a water pool; using a filler to cover the green body, igniting and roasting the green body under air-tight conditions, cooling and cooling to obtain a roasted product; loading the roasted product into a graphitization furnace, pressurizing and transmitting electricity, and shutting off the power; processing the graphitized product into a finished electrode according to the process size.

Description

Technical Field

[0001] The invention relates to the technical field of graphite electrode preparation, and in particular to a method for preparing a large-scale square graphite electrode. Background Art

[0002] The purification and processing of negative electrode materials requires a box-type furnace, which is mainly composed of furnace head electrodes, columns, side plates, bottom plates, cover plates, refractory materials, etc. With the increase in the output of negative electrode material purification, the size of the negative electrode material box-type furnace has also increased, and the specifications and sizes of the square electrodes of the negative electrode material box-type furnace have also gradually increased. With the increase in the size of the square electrodes of the furnace head, the quality requirements for products are also gradually increasing. During the production process, the square electrodes of the furnace head are connected to the transformer busbar to introduce electrical energy into the products in the furnace. Half of the graphite square electrode is subjected to a high temperature of 3000℃ in the furnace, and the other half is cooled by cooling water outside the furnace and connected to the aluminum busbar. The temperature in the water cooling chamber does not exceed 100℃. A product has to withstand a drastic temperature difference, and the product performance and quality are unqualified. It is extremely easy to cause the furnace head electrode to break during the graphitization process of the negative electrode material, and the production is interrupted. Therefore, the larger the size of the graphite square electrode, the higher the requirements for physical and chemical properties such as resistivity, volume density, thermal expansion coefficient, and flexural strength. In order to meet the needs of negative electrode material purification and processing and improve the physical and chemical properties of graphite square electrodes, a process method is adopted in which the calcined product is impregnated and then calcined, and graphitized after the second calcination. However, the graphite square electrode is large in size, and it is difficult for the impregnation asphalt to penetrate into the product, resulting in a layer of impregnation hard shell on the outside of the product, and the internal and external products are not homogeneous, with potential risks of fracture and cracking. The product is calcined twice, which increases the production cost, causes waste of resources, and prolongs the production cycle of the product. Summary of the invention

[0003] In view of this, the present invention provides a method for preparing a large-sized quartzite electrode, the main purpose of which is to provide a method for producing a large-sized quartzite electrode with a short production cycle and low production cost.

[0004] In order to achieve the above object, the present invention mainly provides the following technical solutions:

[0005] The present invention provides a method for preparing a large-scale quartzite electrode, the method comprising the following steps:

[0006] Step 1, calcining the petroleum coke at high temperature in an airtight condition to obtain calcined coke;

[0007] Step 2, crushing the calcined coke into a particle size range of 0-8 mm, and adding the following mass proportions: 6-8 mm 8%-12%, 4-6 mm 8%-10%, 2-4 mm 8%-10%, 0.075-2 mm 10%-15%, 0-0.075 mm 55%-58%, to form a particle mixture;

[0008] Step 3, preheating the particle mixture for 35-45 minutes at a temperature of 130-140° C. to make the particle mixture uniformly mixed;

[0009] Step 4, adding asphalt to the granular mixture to obtain a mixture, wherein the weight of the asphalt is 20%-22% of the weight of the mixture, and heating and kneading the mixture at a temperature of 150±3°C;

[0010] Step 5, after the temperature of the mixture drops to 140±3°C after 8-10min of cooling treatment, the mixture is pushed into a mold, and at the same time, the temperature of the mold is adjusted to 95±2°C, and vibration molding is performed under the conditions of applying pressure and keeping the mold warm, and a green body is obtained after demolding, and the green body is placed in a water pool with a temperature of 20-45°C;

[0011] Step 6: In a roasting furnace, the green body is covered with a filler, and the green body is ignited and roasted under air-tight conditions, and the temperature difference between the fire channels in each temperature section is controlled not to exceed 3° C., and the green body is heated to above 850° C., the ignition is stopped, and the green body is cooled to obtain a roasted product;

[0012] Step 7, the calcined product is loaded into a graphitization furnace, a direct current is passed, a top push pressure is applied, and power is supplied under pressure. When the temperature reaches above 2800°C, power is supplied at a constant power for 5 hours, and then the power is turned off. The product is taken out of the furnace after cooling for 7 days;

[0013] Step eight, using turning, milling, drilling and grinding methods to process the graphitized product into a finished electrode according to the process size.

[0014] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0015] Optionally, in step five, the applied pressure is 18±1 MPa and the mold insulation temperature is 95±2°C.

[0016] Optionally, in step seven, the maximum value of the DC current is 180KA, and the push pressure is 4.5-6MPa.

[0017] Optionally, the filler has a particle size of 2-10 mm.

[0018] Optionally, the size of the finished electrode is 900×900×2200 mm.

[0019] Optionally, in step 4, the heating and kneading process takes 45-55 minutes.

[0020] By means of the above technical solution, the present invention has at least the following advantages:

[0021] Compared with the prior art, the present invention has the characteristics of short production cycle and high production capacity. The existing furnace head conductive electrode needs to go through six production processes: raw material calcination, molding, primary roasting, high pressure impregnation, secondary roasting, graphitization, and machining.

[0022] The present invention strictly controls the volume density during the green body forming process by selecting raw materials and adjusting the particle size ratio, strictly controls the temperature during the primary roasting and graphitization process, eliminates the high-pressure impregnation and secondary roasting processes, and still ensures that various physical and chemical indicators of the product meet the standards, greatly reducing the product production cycle and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic structural diagram of a finished electrode product provided in an embodiment of the present invention.

[0024] The reference numerals in the drawings of the specification include: finished electrode 1, inner cooling hole 2 of square graphite electrode, bolt hole 3, annular concave platform 4. DETAILED DESCRIPTION

[0025] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention application are described in detail below in combination with the preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0026] The following will further introduce the preparation method of the large-scale quartzite electrode of the present invention in detail in conjunction with specific embodiments:

[0027] The preparation method of large-scale angular graphite electrode comprises the following steps:

[0028] Step 1, calcining the petroleum coke at high temperature in an airtight condition to obtain calcined coke;

[0029] Step 2: crushing the calcined coke into particles with a particle size range of 0-8 mm, and then mixing the particles of different particle sizes into a plurality of particle mixtures according to the mass percentages shown in Table 1;

[0030] Step 3, preheating the particle mixture for 35-45 minutes at a temperature of 130-140° C. to make the particle mixture uniformly mixed;

[0031] Step 4: adding asphalt to the granular mixture to obtain a mixture, wherein the weight of the asphalt is 20%-22% of the weight of the mixture, heating and kneading the mixture at a temperature of 150±3° C. for 45-55 minutes, and fine-tuning the amount of asphalt during the kneading process, wherein the fine-tuning amount does not exceed 2% of the process requirement;

[0032] Step 5: After the temperature of the mixture drops to 140±3°C after 8-10min of cooling treatment, the mixture is pushed into a mold, and at the same time, the temperature of the mold is adjusted to 95±2°C, and vibration molding is performed under the conditions of applying a pressure of 18±1Mpa and keeping the mold at 95±2°C. After demolding, a green body is obtained, and the green body is placed in a water pool at a temperature of 20-45°C;

[0033] Step 6: In a roasting furnace, a filler with a particle size of 2-10 mm is used to cover the green body, and the green body is ignited and roasted under air-tight conditions, and the temperature difference between the fire channels in each temperature section is controlled to be no more than 3° C., and the green body is heated to above 850° C., and the ignition is stopped, and the green body is cooled to obtain a roasted product;

[0034] Step 7, the calcined product is loaded into a graphitization furnace, a direct current is passed (the maximum current is 180KA), a top push pressure of 4.5-6MPa is applied, and power is supplied under pressure. When the temperature reaches above 2800°C, power is supplied at a constant power for 5 hours, and then the power is turned off. After cooling for 7 days, the product is taken out of the furnace;

[0035] Step eight, using turning, milling, drilling and grinding methods to process the graphitized product into an electrode product 1 according to the process size. Figure 1 As shown, the size of the finished electrode 1 is 900×900×2200mm, wherein a square graphite electrode inner cooling hole 2 is processed at one end of the finished electrode 1, and the diameter of the square graphite electrode inner cooling hole is 300mm; a bolt hole 3 is processed at one end side of the finished electrode 1, and the length of the bolt hole 3 is 750mm, and the diameter of the bolt hole 3 is 25mm; an annular recess 4 is provided at the opening end of the square graphite electrode inner cooling hole 2, and the outer diameter of the annular recess 4 is 340mm.

[0036] Table 1 Proportion composition of different particle mixtures (mass percentage)

[0037]

[0038]

[0039] Table 2 Test results of physical and chemical indicators of finished electrode products of various embodiments

[0040]

[0041] It can be seen from Table 2 that each embodiment shortens the production cycle and reduces the production cost on the basis of reducing the production process. On this basis, it can also make the physical and chemical indicators of the finished electrode meet the standards and meet the use requirements of the furnace head electrode of the box-type furnace.

[0042] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a large-scale quartzite electrode, characterized in that: The steps include: Step 1, calcining the petroleum coke at high temperature in an airtight condition to obtain calcined coke; Step 2, crushing the calcined coke into a particle size range of 0-8 mm, and adding materials according to the following mass ratio: 6-8 mm 8%-12%, 4-6 mm 8%-10%, 2-4 mm 8%-10%, 0.075-2 mm 10%-15%, 0-0.075 mm 55%-58%, to form a particle mixture; Step 3, preheating the particle mixture for 35-45 minutes at a temperature of 130-140° C. to make the particle mixture uniformly mixed; Step 4, adding asphalt to the granular mixture to obtain a mixture, wherein the weight of the asphalt is 20%-22% of the weight of the mixture, and heating and kneading the mixture at a temperature of 150±3°C; Step 5, after the temperature of the mixture drops to 140±3°C after 8-10min of cooling treatment, the mixture is pushed into a mold, and at the same time, the temperature of the mold is adjusted to 95±2°C, and vibration molding is performed under the conditions of applying pressure and keeping the mold warm, and a green body is obtained after demolding, and the green body is placed in a water pool with a temperature of 20-45°C; Step 6: In a roasting furnace, the green body is covered with a filler, and the green body is ignited and roasted under air-tight conditions, and the temperature difference between the fire channels in each temperature section is controlled not to exceed 3° C., and the green body is heated to above 850° C., the ignition is stopped, and the green body is cooled to obtain a roasted product; Step 7, the calcined product is loaded into a graphitization furnace, a direct current is passed, a top push pressure is applied, and power is supplied under pressure. When the temperature reaches above 2800°C, power is supplied at a constant power for 5 hours, and then the power is turned off. The product is taken out of the furnace after cooling for 7 days; Step eight, using turning, milling, drilling and grinding methods to process the graphitized product into a finished electrode according to the process size.

2. The method for preparing a large-sized angular graphite electrode according to claim 1, characterized in that: In step five, the applied pressure is 18±1 MPa and the mold insulation temperature is 95±2°C.

3. The method for preparing a large-sized prismatic graphite electrode according to claim 1, characterized in that: In step seven, the maximum value of the DC current is 180KA, and the push pressure is 4.5-6MPa.

4. The method for preparing a large-sized angular graphite electrode according to claim 1, characterized in that: The particle size of the filler is 2-10 mm.

5. The method for preparing a large-sized angular graphite electrode according to claim 1, characterized in that: The size of the finished electrode is 900×900×2200 mm.

6. The method for preparing a large-sized angular graphite electrode according to claim 1, characterized in that: In step 4, the heating and kneading process takes 45-55 minutes.

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