Carbon rod and preparation method thereof

Abstract

The invention belongs to the technical field of graphite material production, and relates to a carbon rod which comprises the following raw materials in percentage by mass: 28-30% of low-carbon graphite powder, 28-30% of crystalline flake graphite powder, 16-18% of brand new carbon powder, 8-10% of grinding head material powder, 5-10% of rework material powder, 8-10% of waste carbon rod powder and 2-18% of asphalt. The rework powder is prepared by crushing unqualified semi-finished products in the processing process, and the waste carbon rod powder is powder prepared by crushing crushed finished carbon rods. The invention further discloses a preparation method of the carbon rod, and a carbon rod finished product with stable performance and high resource utilization rate is prepared by recycling waste materials and optimizing a forming and roasting process. By introducing the grinding head material powder, the rework material powder, the waste carbon rod powder and other by-product materials, the production cost is remarkably reduced, and the resource utilization rate is increased. The carbon rod is stable in performance, meets the requirements for breathability, seepage prevention and strength, and gives consideration to both economical efficiency and environmental friendliness.

Description

Technical Field

[0001] The invention belongs to the technical field of graphite material production, and in particular relates to a carbon rod and a preparation method thereof. Background Art

[0002] Carbon rods are widely used in industries such as dry cell batteries, electrolysis, electric heating, metallurgy, chemicals, and new energy. As conductive, thermal, or supporting materials, their performance stability and production costs significantly impact the quality and market competitiveness of downstream products. Traditional carbon rods are typically made from raw materials such as high-quality natural graphite, petroleum coke, and coal tar. While these materials maintain their electrical conductivity, mechanical strength, and air permeability, they are expensive and generate significant amounts of scrap, damaged parts, and processing waste during the production process.

[0003] In actual production, these wastes are difficult to be used directly as recycled raw materials due to their irregular physical form, uneven particle size distribution, high impurity content, difficulty in reusing binders, and inconsistent heat treatment status. The particle sizes of grinding head powder and crushed waste materials vary greatly, and direct use will affect the molding density and mechanical properties of the final carbon rod. The surfaces of rework materials and waste carbon rods are often attached with metal impurities, oxide layers or other process residues. If they are not effectively purified, they can easily lead to a decrease in electrical conductivity. Many waste materials have undergone high-temperature treatment, and their original asphalt binders have been carbonized and ineffective. If they are directly reused, the molding strength and sintering bonding properties are difficult to guarantee. Some waste materials have undergone roasting or graphitization processes at different temperatures and times. The difference in thermal history makes their performance stability in reuse poor, and it is difficult to control product consistency.

[0004] Therefore, the following problems arise: a large proportion of reliance on high-purity graphite and primary raw materials, and a large proportion of raw material costs, especially in large-scale mass production, which puts great pressure on corporate cost control. Grinding head powder, rework materials, waste carbon rods, etc. generated during the processing are often directly discarded or only treated at low value, and are not effectively recycled, resulting in waste of resources. If the above-mentioned waste materials are not recycled in time, it will cause a backlog of industrial solid waste, aggravate environmental pollution problems, and be detrimental to sustainable development. Some traditional carbon rod products are optimized for a single performance and cannot maintain good stability under different working conditions, and lack versatility. The existing process still has problems such as low energy utilization efficiency and inaccurate temperature control in the mixing, molding and roasting stages, which affect the consistency and yield of the products.

[0005] Therefore, there is an urgent need for a new carbon rod preparation technology that can significantly reduce raw material costs, improve resource utilization efficiency, and adapt to multi-scenario applications while ensuring carbon rod performance. Summary of the Invention

[0006] The present invention provides a carbon rod and a preparation method thereof, which are used to solve the existing technical problems.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is: A carbon rod, whose raw materials, calculated by mass percentage, include: 28-30% low-carbon graphite powder, 28-30% flake graphite powder, 16-18% new carbon powder, 8-10% grinding head powder, 5-10% rework powder, 8-10% waste carbon rod powder, and 2-18% asphalt. The grinding head powder is obtained by crushing fragments or powder peeled off from the carbon rod during the carbon rod processing, the rework powder is obtained by crushing unqualified semi-finished products during the processing, and the waste carbon rod powder is powder obtained by crushing broken finished carbon rods.

[0008] As a further improvement of the above technical solution: The carbon rod has a carbon content of 88-92%, a porosity of 20-25%, and an air permeability of 15-18 mL / min.

[0009] A method for preparing a carbon rod comprises the following steps: S1. Grind and sieve the grinding head material, rework material and waste carbon rods respectively; S2. Evenly mix low-carbon graphite powder, flake graphite powder, new carbon powder, grinding head powder, reworked material powder, and waste carbon rod powder according to the ratio of claim 1; S3. The mixture is heated and stirred with asphalt to allow the asphalt to fully bind and form a uniform mixed paste; S4. The mixed paste is pressed into a pie-shaped blank; S5. The pie-shaped blank is extruded into a rod-shaped blank; S6. The rod-shaped body is subjected to a staged calcination carbonization treatment, specifically: first drying and dehydrating at 200°C to 210°C, then gradually heating to 700°C to 710°C for initial oil removal, then heating to 900°C to 910°C for concentrated oil removal, and finally heating to 1180°C to 1200°C for polymerization carbonization; S7. Polish the carbonized rod to obtain a finished carbon rod that meets the specifications.

[0010] As a further improvement of the above technical solution: In S2, the heating and stirring temperature is 160° C. to 170° C., and the stirring time is 55 to 60 minutes.

[0011] The temperature for pressing the cake-shaped blank is 180° C. to 200° C., and the pressing pressure is 15 to 16 MPa.

[0012] The method further comprises immersing the polished carbon rod in paraffin wax at a immersion temperature of 160° C. to 170° C. for 150 to 180 minutes.

[0013] The soaked carbon rods are centrifuged at a speed of 300 to 320 rpm for 59 to 61 seconds.

[0014] The method also includes vacuum treatment of the carbon rod after centrifugation, with a vacuum pressure of -0.095 to -0.098 MPa and a vacuum holding time of 18 to 20 minutes, so as to enhance the anti-permeability and air permeability of the carbon rod.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This application recycles waste carbon materials such as grinding head powder, rework powder and waste carbon rod powder through scientific proportions, which not only effectively reduces the cost of raw materials and resource waste, but also optimizes the microstructure of the carbon rod to a certain extent, and improves its permeability and porosity. Compared with new raw materials, these waste materials that have been treated with high temperature or partially graphitized have more microporous structures and irregular morphologies. More interconnected pore channels can be formed during the re-mixing and molding process, thereby improving the overall porosity and air permeability. At the same time, since these recycled materials have been partially carbonized or graphitized, their thermal stability and structural rigidity are relatively strong. It is easier to stably maintain the pore structure during the high-temperature roasting stage and is not easy to collapse or close the pores, thus helping to achieve high permeability and good gas exchange performance. Therefore, compared with the preparation of completely new raw materials, the reasonable introduction of an appropriate amount of high-temperature waste material not only does not reduce the material performance, but through its naturally formed microstructural characteristics, it achieves better pore structure regulation, which helps to meet the requirements of gas diffusion and electrolyte permeability in applications such as dry batteries.

[0016] By innovatively introducing three industrial by-product powders—grinding head powder, rework powder, and waste carbon rod powder—the company has significantly improved resource recycling efficiency and addressed the severe waste of raw materials and high costs in traditional carbon rod manufacturing. Grinding head powder is the debris that naturally falls off during the carbon rod processing process, rework powder is the reworked waste from unqualified semi-finished products, and waste carbon rod powder is the recycled powder from crushed finished products. These materials are often discarded or treated as low-value in traditional processes, resulting in significant resource waste and an increased environmental burden.

[0017] The present invention pulverizes and sieves these byproduct powders and then adds them to the carbon rod raw material system in a reasonable proportion. This not only ensures the structural integrity and performance requirements of the carbon rods, but also effectively reduces dependence on expensive graphite materials and significantly reduces production costs. Utilizing waste resources not only reduces the cost of raw material procurement but also reduces waste disposal costs, achieving both economic and environmental benefits.

[0018] Furthermore, this formula optimizes the performance balance of carbon rods. The addition of grinding head powder and waste carbon rod powder helps adjust the carbon microstructure, improving the connectivity and uniformity of the pore structure, thereby achieving stable material strength and anti-seepage performance while maintaining air permeability. This method of rationally utilizing byproduct powder not only promotes the efficient use of materials, but also maintains the service life and reliability of carbon rods, greatly satisfying the battery industry's demand for low-cost, high-performance carbon rods.

[0019] In summary, the present invention not only significantly reduces the production cost of carbon rods and reduces waste, but also embodies the organic combination of energy conservation and emission reduction, resource recycling and cost control. It is in line with the development trend of green manufacturing, and also brings significant economic and social benefits to carbon rod manufacturing companies, promoting the sustainable development of the industry. The stable performance and production efficiency of carbon rods are guaranteed by scientific preparation technology. This technology is suitable for large-scale industrial production, and is particularly suitable for the battery manufacturing industry, which is cost-sensitive and has high requirements for environmental protection, and promotes the development of carbon rod production in the direction of green, low consumption and high efficiency. DETAILED DESCRIPTION

[0020] To facilitate understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0021] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0022] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0023] Example 1: This embodiment is a carbon rod with optimal comprehensive performance.

[0024] The following carbon rod raw material was prepared using the following ratio: 170 kg of low-carbon graphite, 100 kg of new carbon powder, 55 kg of grinding head powder, 170 kg of flake graphite, 30 kg of waste carbon rod powder, and 25 kg of rework powder, for a total weight of 550 kg. The waste carbon rod powder and rework powder accounted for approximately 10% of the total raw material, reducing costs while ensuring the material's basic structural stability and high carbon content.

[0025] The above raw materials are mixed and stirred at 160-170°C for 50-60 minutes to form a uniformly mixed asphalt bonding paste; then, the mixture is hot-pressed at 180-200°C, with the pressing pressure controlled at 15-16 MPa, and pressed into cake-shaped preformed blocks; then, it is extruded into carbon rod blanks through extrusion molding equipment.

[0026] Then the calcination treatment is carried out in sequence: drying and dehydration at 200-220°C, then heating to 700-710°C for initial oil discharge, then heating to 900-910°C for concentrated oil discharge, and finally heating to 1180-1200°C to complete the polymerization carbonization treatment.

[0027] Finally, the carbon rod blank is polished to obtain a finished carbon rod that meets the dimensional requirements. Optionally, the polished carbon rod is immersed in paraffin wax at 160-170°C for 150-180 minutes, then centrifuged at 300-320 rpm for 59-61 seconds, and finally vacuum-treated at -0.095-0.098 MPa for 18-20 minutes to improve its anti-seepage and air permeability properties.

[0028] The performance parameters of the finished carbon rod are as follows: carbon content of about 91%, porosity of 22%, air permeability of about 16.5 mL / min, volume resistivity of about 10.2 μΩ·m, and flexural strength of 13.5 MPa.

[0029] If used in low temperature or high humidity environment, it is recommended to increase the amount of flake graphite to 180 kg to enhance moisture resistance and electrical conductivity. If cost control is required, the amount of waste carbon rod powder can be increased to 40 kg to reduce material procurement costs.

[0030] It is suitable for use in environments where ordinary carbon-zinc batteries and low-power batteries are used, such as remote controls, clocks and other household electronic products.

[0031] Comparative Example 1: This comparative example corresponds to Example 1 and is used to compare the effects of not using waste materials on carbon rod performance. The raw material ratio is: 240 kg low-carbon graphite, 150 kg new carbon powder, 160 kg flake graphite, and 100 kg coal tar (total 650 kg). No grinding head dust, rework material, or waste carbon rod powder was used. The rest of the process was the same as in Example 1.

[0032] The carbon rod's performance parameters include: 92% carbon content, 16% porosity, 6 mL / min air permeability, approximately 9.5 μΩ·m volume resistivity, and 13.9 MPa flexural strength. However, its disadvantages include being made entirely of newly purchased raw materials, resulting in a cost increase of approximately 40%. The rod also exhibits significantly insufficient air permeability and an overly dense structure, which impedes electrolyte penetration and gas diffusion, and can easily cause bulging during high-load discharge.

[0033] Example 2: This embodiment is a carbon rod with optimized air permeability.

[0034] The following raw material mix was used to prepare the carbon rods: 150 kg of low-carbon graphite, 95 kg of new carbon powder, 70 kg of grinding head powder, 160 kg of flake graphite, 45 kg of waste carbon rod powder, and 30 kg of rework powder, for a total of 550 kg. The waste material ratio was approximately 13.6%, maximizing the porosity while maintaining strength.

[0035] The raw materials were heated and stirred at 165-170°C for 60 minutes to thoroughly mix the asphalt and various particles to form a uniformly cohesive paste. The mixture was then hot-pressed into a cake-shaped blank at 185-195°C under a pressure of 15 MPa. It was then extruded into rod-shaped blanks using an extruder. The calcination stages were: dehydration at 200-210°C, crude oil removal at 700-710°C, concentrated oil removal at 900-910°C, and polymerization and carbonization at 1180-1200°C. After carbonization, the rods were polished and immersed in paraffin wax at 160-170°C for 180 minutes. They were then centrifuged at 300 rpm for 60 seconds and vacuum-treated at -0.096 MPa for 20 minutes to enhance the openness of the interconnected pores.

[0036] The finished carbon rod's performance parameters include: carbon content of approximately 89%, porosity of 24%, air permeability of up to 18 mL / min, volume resistivity of approximately 11.5 μΩ·m, and flexural strength of 12.3 MPa. Suitable for battery systems operating in high-temperature environments, particularly suitable for outdoor use in summer, lighting batteries, and applications requiring high anti-bulging properties.

[0037] Comparative Example 2: This comparative example corresponds to Example 2 and is used to compare the effects of high asphalt addition on porosity and conductivity.

[0038] The raw material ratio is: 200 kg of low-carbon graphite, 110 kg of new carbon powder, 170 kg of flake graphite, 70 kg of coal tar, and 70 kg of grinding head powder, with a total weight of 620 kg. No rework material or waste carbon rod powder is used. The remaining process parameters are the same as in Example 2.

[0039] The performance parameters of the finished carbon rod were: carbon content 87%, porosity 19%, air permeability approximately 10 mL / min, volume resistivity approximately 12.8 μΩ·m, and flexural strength 11.4 MPa. Disadvantages: The high asphalt content and incomplete carbonization resulted in poor pore connectivity, heavy residual organic impurities, and significantly lower overall air permeability and conductivity than those in Example 2.

[0040] Example 3: This embodiment is a carbon rod with high carbon purity and stable product.

[0041] The following raw material mix was used to prepare the carbon rods: 180 kg of low-carbon graphite, 110 kg of new carbon powder, 40 kg of grinding head powder, 180 kg of flake graphite, 20 kg of waste carbon rod powder, and 20 kg of rework powder, for a total of 550 kg. The high proportion of new material ensured structural density and electrical conductivity.

[0042] The mixture is stirred at 170°C for 65 minutes to ensure that the binder fully penetrates the graphite particle surface. Subsequently, a preform is formed by hot pressing at 200°C with a pressure controlled at 16 MPa to form a cake-shaped preform. A rod-shaped green body is then extruded through a screw extruder. Calcination is performed in stages: drying at 200-220°C, initial oil removal at 700°C, concentrated oil removal at 900°C, and finally, polymerization and carbonization are completed at 1200°C. After polishing, the carbon rods can be impregnated with paraffin wax and vacuum treated as needed.

[0043] The finished carbon rod's performance parameters include: carbon content up to 92%, porosity of 21%, air permeability of 15 mL / min, volume resistivity of 9.1 μΩ·m, and flexural strength of 14.7 MPa. Suitable for industrial applications requiring high conductivity and long discharge times, such as instrument batteries, emergency lighting, and energy storage systems.

[0044] Comparative Example 3: This comparative example corresponds to Example 3 and is used to compare the effects of conventional coal char raw material ratios on conductivity and stability. The raw material ratios are: 220 kg flake graphite, 100 kg coal char, 80 kg petroleum coke, and 150 kg coal tar pitch, for a total of 550 kg. No grinding head dust, rework, or waste carbon rod powder was used. The process flow is the same as in Example 3.

[0045] The finished carbon rod's performance parameters include: carbon content approximately 88%, porosity 17%, air permeability approximately 7 mL / min, volume resistivity 12.2 μΩ·m, and flexural strength 13.1 MPa. Disadvantages: While highly dense, it exhibits low electrical conductivity and severely insufficient air permeability, making it unsuitable for high-discharge efficiency applications. It also fails to utilize waste materials, resulting in high costs and poor environmental performance.

[0046] A summary comparison of the embodiments and comparative examples is shown in the table below.

[0047]

Claims

1. A carbon rod, characterized in that: Its raw materials, calculated by mass percentage, include: 28-30% low-carbon graphite powder, 28-30% flake graphite powder, 16-18% new carbon powder, 8-10% grinding head powder, 5-10% rework powder, 8-10% waste carbon rod powder, and 2-18% asphalt. The grinding head powder is obtained by crushing fragments or powder peeled off from the carbon rod during the carbon rod processing, the rework powder is obtained by crushing unqualified semi-finished products during the processing, and the waste carbon rod powder is a powder obtained by crushing broken finished carbon rods.

2. The carbon rod according to claim 1, characterized in that The carbon rod has a carbon content of 88-92%, a porosity of 20-25%, and an air permeability of 15-18 mL / min.

3. A method for preparing a carbon rod, characterized in that: The following steps are involved: S1. Grind and sieve the grinding head material, rework material and waste carbon rods respectively; S2. Evenly mix low-carbon graphite powder, flake graphite powder, new carbon powder, grinding head powder, reworked material powder, and waste carbon rod powder according to the ratio of claim 1; S3. The mixture is heated and stirred with asphalt to allow the asphalt to fully bind and form a uniform mixed paste; S4. The mixed paste is pressed into a pie-shaped blank; S5. The pie-shaped blank is extruded into a rod-shaped blank; S6. The rod-shaped body is subjected to a staged calcination carbonization treatment, specifically: first drying and dehydrating at 200 ℃ ~ 210 ℃, then gradually heating to 700 ℃ ~ 710 ℃ for initial oil discharge, then heating to 900 ℃ ~ 910 ℃ for concentrated oil discharge, and finally heating to 1180 ℃ ~ 1200 ℃ for polymerization carbonization; S7. Grind the carbonized rod to obtain a finished carbon rod that meets the specifications.

4. The method for preparing a carbon rod according to claim 3, wherein: In S2, the heating and stirring temperature is 160° C. to 170° C., and the stirring time is 55 to 60 minutes.

5. The method for preparing a carbon rod according to claim 3, wherein: The temperature for pressing the cake-shaped blank is 180° C. to 200° C., and the pressing pressure is 15 to 16 MPa.

6. The method for preparing a carbon rod according to claim 3, wherein: The method further comprises immersing the polished carbon rod in paraffin wax at a immersion temperature of 160° C. to 170° C. for 150 to 180 minutes.

7. The method for preparing a carbon rod according to claim 3, wherein: The soaked carbon rods are centrifuged at a speed of 300 to 320 rpm for 59 to 61 seconds.

8. The method for preparing a carbon rod according to claim 3, wherein: The method also includes vacuum treatment of the carbon rod after centrifugation, with a vacuum pressure of -0.095 to -0.098 MPa and a vacuum holding time of 18 to 20 minutes, so as to enhance the anti-permeability and air permeability of the carbon rod.

Images