A special graphite production process improvement method for improving asphalt coating uniformity

Abstract

The application relates to the technical field of graphite preparation, in particular to a special graphite production process improvement method for improving pitch coating uniformity. The method comprises the following steps: high quinoline pitch is prepared by reforming pitch and quinoline insoluble powder melting; the high quinoline pitch is subjected to vacuum distillation, then is screened through different particle size sieves, and then is put into a mold for pressure to obtain a green body; after the green body is baked, the pitch is carbonized to obtain graphite; when the high quinoline pitch is prepared, an ultrasonic image of a melting furnace is obtained, and multi-scale texture distribution in the ultrasonic image is analyzed; and then the temperature of the melting furnace is adjusted based on comparison of image texture feature changes and threshold values in different states. The application solves the problems of pitch melting deficiency or excessive heating caused by pitch melting state being unknown, and improves the pitch coating uniformity of the special graphite.

Description

Technical Field

[0001] This application relates to the field of graphite preparation technology, specifically to an improved method for the production process of special graphite to enhance the uniformity of asphalt coating. Background Technology

[0002] Graphite is a carbon anode material widely used in the semiconductor field, but uncoated graphite presents several problems during application. For example, during the charging and discharging process of lithium batteries, lithium ions repeatedly insert and extract between graphite layers. Since the interlayer spacing of graphite is usually smaller than the interplanar spacing of layered lithium compounds, this structural mismatch causes repeated changes in the graphite interlayer spacing, leading to material peeling, pulverization, and potentially causing problems such as co-intercalation or decomposition of organic solvents, affecting battery cycle performance. Coating the graphite surface with high-softening-point pitch can effectively solve this problem.

[0003] In existing special graphite production processes, such as CN118724592A "A method for preparing high-performance carbon graphite materials," asphalt is first dry-mixed with other raw materials, then kneaded with the help of a binder, followed by grinding, static pressing, and finally calcination and graphitization to obtain high-performance graphite materials. In CN113999010A "A method for preparing high-performance special graphite," asphalt is used as a binder, forming a paste by coating the surface of raw material powder with asphalt. After grinding, the paste powder with a higher specific gravity is screened for molding, and finally, special graphite is obtained through multiple calcination and graphitization treatments. In existing methods, the influence of the asphalt melting state on the uniformity of asphalt coating is not considered during the asphalt coating process. If the heating temperature is insufficient during the asphalt heating process, the asphalt will not melt sufficiently; if the temperature is too high, it will easily lead to excessive coking of the asphalt. Both of these situations will cause uneven distribution of the asphalt coating layer, resulting in different carbon structure densities in different regions of the graphite. This will cause the graphite material to have a low degree of local graphitization, leading to unqualified graphite materials. Summary of the Invention

[0004] To address the technical problem of uneven distribution of asphalt coating, this application provides an improved method for the production process of special graphite to enhance the uniformity of asphalt coating. The specific technical solution adopted is as follows:

[0005] This application proposes an improved method for the production process of special graphite to enhance the uniformity of asphalt coating. The method includes the following steps:

[0006] High-quinoline asphalt was prepared by melting modified asphalt and quinoline insoluble powder in a melting furnace;

[0007] S1, ultrasonic sensors and two sets of receivers are installed on the melting furnace to collect ultrasonic images;

[0008] S2, perform multi-scale analysis on the foreground region of the ultrasound image to obtain its texture features, and then combine the pixel values ​​to obtain the texture distribution features;

[0009] S3, preset temperature control level, determines two judgment thresholds by the texture distribution feature value of the ultrasonic image before heating to the softening point temperature. Based on different physical states of asphalt, the temperature of the melting furnace is adjusted by comparing the change rate of the texture distribution feature value of each subsequent cycle with the previous cycle of different groups of receivers with the judgment threshold.

[0010] The high-quinoline pitch was subjected to vacuum distillation and cooled to room temperature to obtain the precursor.

[0011] The precursors were analyzed and then ground into powder, which was then sieved using different particle sizes.

[0012] Powders of different particle sizes are placed into a mold and pressed to obtain a rectangular green body;

[0013] The rectangular raw embryo is roasted to obtain the roasted product;

[0014] Graphite is obtained by graphitizing the roasted product.

[0015] In the above-mentioned solution, this application takes into account that in the existing special graphite preparation process, the influence of the melting state of the asphalt on the uniformity of the asphalt coating process is not considered during the asphalt coating process. This leads to overheating or underheating of the asphalt when the temperature is too high or too low, resulting in unqualified graphite material preparation. In this application, by acquiring ultrasonic images of the asphalt during the melting process from multiple angles and combining them with the density change characteristics of the asphalt during the heating process, the texture characteristics of the ultrasonic images during the asphalt melting process are analyzed. Therefore, a method for staged temperature control of the asphalt melting furnace is proposed. By analyzing the density change differences of the asphalt during the actual melting process from multiple angles, the temperature heating rate in the melting furnace is dynamically adjusted. This solves the problem of insufficient melting or overheating of the asphalt caused by the unknown melting state of the asphalt, and improves the uniformity of the asphalt coating of special graphite.

[0016] In one embodiment, the proportion of quinoline insolubles in the prepared high-quinoline asphalt is 25-30%, the coking value is 70-75%, and the softening point of the selected modified asphalt needs to be greater than 110°C.

[0017] In one embodiment, the method of performing multi-scale analysis on the foreground region of an ultrasound image to obtain its texture features, and then combining this with pixel values ​​to obtain texture distribution features, is as follows:

[0018] A preset scale set is used as input. The LBP value of the pixel is obtained by using the LBP algorithm with the foreground region of the ultrasound image and the scale set as input. The average value of LBP value at different scales is used as the texture feature of the pixel.

[0019] Calculate the mean of the texture features of all pixels in the foreground region and obtain the maximum pixel value. Calculate the texture distribution features based on both.

[0020] In one embodiment, the texture distribution features are positively correlated with the entropy values ​​of the pixel texture features in the foreground region and negatively correlated with the maximum pixel value in the foreground region.

[0021] In one embodiment, the method for determining the two judgment thresholds by analyzing the texture distribution feature values ​​of the ultrasound image before heating to the softening point temperature is as follows:

[0022] The time period during which the melting furnace temperature is raised to the softening point temperature is recorded as the heating time period;

[0023] All ultrasound images during the heating period are sorted and labeled according to time, and their texture distribution features are combined into a feature sequence. The feature sequence is fitted with a straight line, and the slope of the fitted line is obtained. The absolute value of the slope is used as the first judgment threshold.

[0024] The difference sequence of the feature sequence is calculated by the first-order difference algorithm, and the first quartile of the absolute value of all difference values ​​in the difference sequence is used as the second judgment threshold.

[0025] In one embodiment, the method for adjusting the furnace temperature by comparing the rate of change of texture distribution feature values ​​of different groups of receivers in each subsequent cycle with the previous cycle and a judgment threshold based on different physical states of asphalt is as follows:

[0026] After the temperature reaches the softening point, for a set of receivers, the slope of the texture distribution feature value of each ultrasound image and the adjacent previous ultrasound image is calculated; the slopes of the two sets of receivers are recorded as the first slope and the second slope, respectively.

[0027] Phase 1:

[0028] When both the first slope and the second slope are less than or equal to the first judgment threshold, the temperature control level is... ;

[0029] When either the first slope or the second slope is greater than the first judgment threshold, the temperature control level is: ;

[0030] When both the first slope and the second slope are greater than the first judgment threshold, the temperature control level is: At this point, the above judgments on the ultrasound images are no longer made, and the second stage of judgment is performed.

[0031] Phase Two:

[0032] When the absolute values ​​of both the first and second slopes are less than the second judgment threshold, the temperature control level is... ;

[0033] When both the first and second slopes are greater than 0, and the absolute value of one of them is greater than the second judgment threshold, then the temperature control level is... ;

[0034] When both the first slope and the second slope are greater than 0 and their absolute values ​​are greater than the second judgment threshold, the temperature control level remains unchanged.

[0035] Condition 1: The first slope is greater than 0 and its absolute value is greater than the second judgment threshold, while the second slope is less than 0; Condition 2: The second slope is greater than 0 and its absolute value is greater than the second judgment threshold, while the first slope is less than 0; If either condition is met, the temperature control level is [condition 1]. ;

[0036] When both the first and second slopes are less than 0, and their absolute values ​​are both greater than the second judgment threshold, the temperature control level is [value missing]. At this point, the above-mentioned judgments on the ultrasound images are no longer made, and the third-stage judgment is performed.

[0037] Phase Three:

[0038] Condition 1: The first slope is less than the first judgment threshold, and the second slope is greater than the first judgment threshold; Condition 2: The first slope is greater than the first judgment threshold, and the second slope is less than the first judgment threshold; If either condition is met, the temperature control level is [condition 1]. ;

[0039] When both the first slope and the second slope are greater than or equal to the first judgment threshold, the temperature control level is set to... .

[0040] When both the first slope and the second slope are less than the first judgment threshold, no temperature adjustment is performed, and temperature control is completed.

[0041] The temperature control level .

[0042] In one embodiment, when high-quinoline asphalt is subjected to vacuum distillation, the pressure inside the distillation reactor is 10-30 mmHg, and the asphalt inside the reactor is heated to 300°C.

[0043] In one embodiment, the precursors are sieved to particle sizes of D10=4-6μm, D50=10-15μm, and D90=25-30μm during milling.

[0044] In one embodiment, when powders of different particle sizes are placed into a mold and pressed, the pressing range is 120-140 MPa and the density is 1.35-1.40 g / cm3.

[0045] In one embodiment, when graphitizing calcined products to obtain graphite, the pitch coke / petroleum coke used is in the range of 10-30mm, and the temperature is increased to 2800-3000℃.

[0046] The beneficial effects of this application are as follows:

[0047] This application addresses the problem that existing special graphite preparation processes fail to consider the impact of the asphalt's melting state on the uniformity of asphalt coating during the asphalt coating process. This leads to overheating or underheating of the asphalt due to excessively high or low temperatures, resulting in substandard graphite materials. This application addresses this issue by acquiring ultrasonic images of the asphalt during the melting process from multiple angles and analyzing the density changes during asphalt heating. The method of phased temperature control in the asphalt melting furnace is then proposed. By analyzing the density differences during the actual melting process of asphalt from multiple angles, the heating rate within the melting furnace is dynamically adjusted. This solves the problem of insufficient or excessive asphalt melting caused by the unknown melting state, thereby improving the uniformity of asphalt coating in special graphite. Attached Figure Description

[0048] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 A flowchart illustrating an improved method for producing special graphite to enhance the uniformity of asphalt coating, provided in one embodiment of this application;

[0050] Figure 2 A flowchart illustrating the method for controlling temperature during melting in a melting furnace;

[0051] Figure 3 Layout diagram of sensors and receivers for the melting furnace;

[0052] Figure 4 This is a schematic diagram illustrating the changing trend of the first eigenvalue. Detailed Implementation

[0053] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of an improved method for producing special graphite to improve the uniformity of asphalt coating according to this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0055] An example of an improved method for producing special graphite to enhance the uniformity of asphalt coating:

[0056] The following description, in conjunction with the accompanying drawings, details a specific scheme for an improved method of special graphite production process to enhance the uniformity of asphalt coating provided in this application.

[0057] Please see Figure 1 The diagram illustrates a flowchart of an improved process for producing special graphite to enhance the uniformity of asphalt coating, according to an embodiment of this application. The method includes the following steps:

[0058] Step S001: The modified asphalt and quinoline insoluble powder are melted in a melting furnace to obtain high-quinoline asphalt.

[0059] In the graphite production process, high-quinoline pitch is selected as the raw material, with a quinoline insoluble content of 25-30% and a coking value of 70-75%. It is prepared by adding quinoline insolubles to modified pitch with a softening point greater than 110℃. In this embodiment, the quinoline insoluble content is 25%, the coking value is 75%, and the softening point is 130℃.

[0060] When introducing quinoline-insoluble matter, the modified asphalt needs to be heated and melted in an asphalt melting furnace. Then, while stirring, the quinoline-insoluble matter powder is added evenly. The mixture is then cooled at room temperature in the asphalt melting furnace for 2-4 hours to obtain high-quinoline asphalt. Before use, the high-quinoline asphalt needs to be pulverized into powder with a particle size of less than 1 mm using an impact crusher. In this embodiment, the asphalt is cooled at room temperature in the asphalt melting furnace for 3 hours.

[0061] During the melting process of modified asphalt, the temperature range of the melting furnace is [120℃, 200℃]. The electromagnetic ultrasonic sensor is made of neodymium iron boron with a melting point of 1150℃, and can work normally during asphalt melting.

[0062] When melting modified asphalt in a melting furnace, it is necessary to control the furnace temperature. Specific control methods are as follows: Figure 2 As shown.

[0063] S1, ultrasonic sensors and two sets of receivers are installed on the melting furnace to collect ultrasonic images.

[0064] During the melting of modified asphalt, uneven stirring and heating may lead to different degrees of melting in different areas of the melting furnace, resulting in uneven asphalt melting and affecting the uniformity of asphalt coating; therefore, in this application, if Figure 3As shown, an electromagnetic ultrasonic sensor and two sets of receivers are deployed on the asphalt melting furnace to collect data on the asphalt inside the furnace from multiple angles. Four receivers arranged vertically form a group. The ultrasonic sensor is on one side of the asphalt melting furnace, and the two sets of receivers are on the other side. A certain distance exists between the two sets of receivers, which can be set according to actual conditions; this application does not impose any limitations. In this embodiment, the distance between the receivers is 0.3m.

[0065] After deploying the electromagnetic ultrasonic sensor and two sets of receivers, ultrasonic tomography is used to reconstruct images from the data collected by each receiver in each acquisition cycle. Each acquisition cycle yields a corresponding ultrasonic image. In this embodiment, the interval between two consecutive acquisition cycles for all receivers is set to 10 seconds, and each acquisition cycle is 20 seconds. In the ultrasonic image, each pixel value is the energy attenuation coefficient of the ultrasonic transmission signal; the higher the density of the penetrated object, the smaller this coefficient. During ultrasonic imaging, noise and artifacts often appear in the reconstructed images due to environmental electromagnetic interference, sensor noise, and other factors. Therefore, in this embodiment, a median filtering algorithm is used to filter the acquired ultrasonic images to eliminate pulse noise or interference from isolated points. Furthermore, an adaptive threshold segmentation algorithm is used to perform threshold segmentation on all ultrasonic images, separating the foreground and background regions of each ultrasonic image. Ultrasonic tomography, median filtering, and adaptive threshold segmentation are all formulaic techniques within the field; the specific calculation methods will not be elaborated further.

[0066] At this point, the foreground and background regions of the ultrasound image have been obtained.

[0067] S2, perform multi-scale analysis on the foreground region of the ultrasound image to obtain its texture features, and then combine the pixel values ​​to obtain the texture distribution features.

[0068] During the heating process of modified asphalt in the melting furnace, when the temperature enters the range where the asphalt softens to melt, the parts in more contact with the heat source (e.g., asphalt near the wall) will melt first. As the asphalt changes from a solid to a liquid state, its density decreases. When the asphalt is not completely melted, there will be both lower-density melted asphalt and higher-density unmelted asphalt in the furnace. In ultrasonic images, the lower the density of the liquid asphalt, the larger the corresponding pixel value. This indicates that if the contrast of pixel values ​​is significant in the ultrasonic image, it means that the asphalt in the melting furnace is not completely melted. If uneven heating in the furnace causes persistent local density differences, heat cannot be transferred from the melted low-density asphalt to the unmelted high-density asphalt. This hinders the uniform diffusion of heat, causing some solid asphalt to melt later due to insufficient heat. This results in asynchronous melting processes, making it impossible to obtain uniformly melted asphalt, and consequently affecting the uniformity of the asphalt coating.

[0069] Based on the above analysis, during the melting process of solid asphalt, the resulting liquid asphalt is viscous and adheres to the surface of the solid asphalt to varying degrees. The local density of the asphalt within the furnace may be uneven, leading to deviations in the texture features of each pixel in the ultrasonic image. Therefore, different scales are set for the ultrasonic image to obtain texture features at different scales. In this embodiment, a set of scales is set. The algorithm takes all foreground region pixels and scale sets in the ultrasound image as input and uses the LBP algorithm to calculate the texture features of each foreground region pixel at different scales.

[0070] Specifically, for each pixel, a window is constructed centered on it, with the side length of the window as the scale. For example, if the scale is 3, then the side length of the window is 3. The LBP value of the pixel is calculated based on this window. If the pixel is an edge pixel, a linear interpolation algorithm is used to fill the missing values ​​within the window. The LBP values ​​of the pixel are calculated at all scales, and the mean value is calculated. This mean value is used as the texture feature of the pixel.

[0071] A larger texture feature value indicates a greater contrast between a pixel and its neighboring pixels. By using a normalization method based on maximum and minimum values, the texture features of all foreground region pixels in the ultrasound image are normalized, and the entropy value of the texture features is calculated using the information entropy calculation method.

[0072] The texture distribution features of the ultrasound image are calculated based on the entropy value of the texture features in the foreground region and the pixel value in the foreground region.

[0073] The texture distribution features are positively correlated with the entropy values ​​of the pixel texture features in the foreground region, and negatively correlated with the maximum pixel value in the foreground region.

[0074] It should be noted that positive correlation means that when one variable increases, the other variable also increases, and the two variables change in the same direction. When one variable changes from large to small or from small to large, the other variable also changes from large to small or from small to large. The specific relationship is determined by the actual application, and this application does not impose any special restrictions.

[0075] It should be noted that negative correlation means that when one variable increases, the other variable decreases accordingly, and the two variables change in opposite directions. When one variable changes from large to small or from small to large, the other variable also changes from small to large or from large to small. The specific relationship is determined by practical application, and this application does not impose any special restrictions.

[0076] Preferably, in this embodiment, the expression for the texture distribution features of the ultrasound image is:

[0077] , The normalized value represents the entropy of the pixel texture features in the foreground region of the i-th ultrasound image. This represents the normalized value of the maximum pixel value in the foreground region of the i-th ultrasound image. Represents the hyperbolic tangent function. This represents the texture distribution characteristics of the i-th ultrasound image. The normalization method used is the minimum-maximum normalization method.

[0078] It can reflect the distribution of pixel values ​​in the foreground region within an ultrasound image. A larger value indicates a more discrete pixel value distribution and more complex texture features in the foreground region of the ultrasound image. The larger; This represents the maximum pixel value among all pixels in the foreground region. According to the principle of ultrasonic transmission imaging, the greater the material density, the smaller the pixel value in the ultrasonic image. Since solid asphalt has a greater density than liquid asphalt, and in the initial and final stages of asphalt melting, the furnace may contain only solid or liquid asphalt at this time... It is not possible to distinguish between these two situations, therefore... Chinese combination This is to distinguish between the two cases, namely, when all pixels are solid asphalt and liquid asphalt, the texture complexity is relatively small.

[0079] Thus, the texture distribution features of the ultrasound image were obtained.

[0080] S3, preset temperature control level, determines two judgment thresholds by the texture distribution feature value of the ultrasonic image before heating to the softening point temperature. Based on different physical states of asphalt, the temperature of the melting furnace is adjusted by comparing the change rate of the texture distribution feature value of each subsequent cycle with the previous cycle of different groups of receivers with the judgment threshold.

[0081] Under the combined effects of temperature and stirring, the physical state of asphalt undergoes phased changes, specifically a transition from solid to liquid. During this process, the density of the asphalt changes accordingly. For the same asphalt density, the ultrasonic image shows a relatively uniform density, with solid asphalt having a higher density than liquid asphalt. When solid asphalt dominates the melting furnace, the attenuation of the ultrasonic projection signal is relatively uniform, resulting in a larger texture distribution feature in the ultrasonic image. After continuous melting for a period, the content of liquid and solid asphalt tends to balance, and the attenuation of the ultrasonic projection signal becomes uneven. At this point, the pixel value texture features in the ultrasonic image are more pronounced, and the texture distribution feature becomes larger. Towards the end of melting, liquid asphalt dominates the melting furnace, and the texture distribution feature of the ultrasonic image becomes smaller. This texture distribution feature is denoted as the first feature value, and the change of the first feature value over time is as follows: Figure 4 As shown.

[0082] When the melting furnace starts heating, the heating temperature must be greater than or equal to the softening point of the asphalt. At this time, the solid asphalt may not start to melt as a whole because of the lag in internal heat conduction or the fact that the internal temperature of the block has not yet reached the phase change point uniformly. At this time, the continuous first characteristic value will not change significantly, which may affect the overall process rhythm and may affect the uniformity of the subsequent asphalt coating. Therefore, it is necessary to increase the furnace temperature to accelerate melting.

[0083] When the asphalt in the melting furnace first begins to melt, the content of solid asphalt is much greater than that of liquid asphalt. Due to uneven heating, the solid and liquid asphalt may have different degrees of contact at different locations, or some areas may be in thermal dead zones or affected by the stirring effect, resulting in small areas where the solid and liquid asphalt have less contact. This leads to inconsistent melting processes. At this time, the degree of change between the first characteristic values ​​corresponding to the data of the two sets of receivers at the current moment is different, resulting in uneven physical properties of the melted asphalt. This directly affects the uniformity of the subsequent asphalt coating. Therefore, it is also necessary to increase the heating rate in the furnace.

[0084] When liquid asphalt dominates in the melting furnace, the remaining solid asphalt is often dispersed in the form of small particles, resulting in a smaller heat transfer area and a decreased melting rate. At the same time, it is necessary to avoid overheating the liquid asphalt. If the heating is not properly controlled, it may cause local overheating or residual solid particles, which will affect the homogenization of the final asphalt and thus affect the uniformity of the subsequent asphalt coating. In this case, the heating rate in the melting furnace needs to be reduced. At this time, the first characteristic value will tend to the minimum value. When the degree of change of the first characteristic value corresponding to the two sets of receivers is the same and the degree of change is the same as the degree of change when melting begins, it indicates that the asphalt has completely melted.

[0085] Based on the above analysis, for each group of receivers, the first characteristic value can be obtained from the ultrasound image. All the first characteristic values ​​of each group of receivers are sorted in time sequence and recorded as characteristic change curves.

[0086] Set temperature control level: Celsius Celsius Celsius, when the temperature control level is "Time" indicates that by increasing the output power of the heating equipment inside the furnace, the temperature inside the furnace is increased by 3 degrees Celsius per minute.

[0087] The modified asphalt selected has a softening point greater than or equal to 110 degrees Celsius; in this embodiment, 130 degrees Celsius is used. During asphalt melting, the temperature of the melting furnace is first... The process involves slowly heating the furnace from room temperature to the softening point, which in this embodiment is 130 degrees Celsius. The time period during which the furnace temperature is raised to the softening point is defined as the heating time period. During this heating time period, all ultrasound images are sorted and numbered in chronological order. The first feature value of each ultrasound image is calculated, and all first feature values ​​are sorted in chronological order to form a feature sequence. The feature sequence is fitted using the least squares method, and the slope of the fitted line is calculated. Its absolute value is used as the first judgment threshold. The difference sequence of the feature sequence is calculated using a first-order difference algorithm, and the first quartile of the absolute values ​​of all difference values ​​in the difference sequence is used as the second judgment threshold. When fitting the line, the horizontal axis represents the sequence number of the ultrasound image.

[0088] After heating to the softening point temperature, if the acquisition period at this time is the xth period, then for the ultrasound images of each group of receivers, the first feature value of the ultrasound images in the xth period and the (x-1)th period is calculated, and the slope of the first feature value of adjacent periods is calculated. Thus, for each of the two groups of receivers, a slope of change is obtained, denoted as […]. and .

[0089] like and If all values ​​are less than or equal to the first judgment threshold, it indicates that the first characteristic value is within normal fluctuation, meaning that the asphalt has not yet begun to melt. In this case, the temperature of the melting furnace needs to be increased to accelerate the melting of the asphalt. The temperature control level should be set to [value missing]. .

[0090] like Less than or equal to the first judgment threshold Greater than the first judgment threshold or Less than or equal to the first judgment threshold When the value exceeds the first judgment threshold, it indicates that the first characteristic value is in the rising stage, meaning that the asphalt has localized melting, but the overall melting has not yet fully begun. At this time, in order to achieve overall melting of the asphalt, the temperature control level is set to... .

[0091] like and When all values ​​exceed the first judgment threshold, it indicates that the asphalt has entered the melting stage. At this point, to accurately control the melting temperature, the temperature control step size should be reduced to achieve a smooth transition, and the temperature control level should be set to [value missing]. .

[0092] when and When all values ​​are greater than the first judgment threshold, the temperature control level will be set to... When the first characteristic value begins to rise steadily, solid asphalt begins to melt, and the content of liquid asphalt increases; monitoring is performed for each acquisition cycle, and this cycle is recorded as the y-th cycle. At this time, the first characteristic value of both sets of receivers will begin to rise with time. and To proceed with the next stage of assessment.

[0093] like and If the absolute values ​​of both sets of receivers are less than the second judgment threshold, it indicates that the first characteristic values ​​of both sets of receivers are in a normal fluctuation state during the same period, and the asphalt in the melting furnace is melting uniformly, but the melting rate is slow. Therefore, the temperature control level is set to... .

[0094] when and Both are greater than zero and and When one of the absolute values ​​is greater than the second judgment threshold, it indicates that the first characteristic value under one group of receivers is in a normal increasing state in the same period, while the first characteristic value under another group of receivers is in a normal fluctuating state. This indicates that the asphalt is not melting evenly in some areas, so the level is set to... .

[0095] when and Both are greater than zero and and When the absolute values ​​of both sets of receivers are greater than the second judgment threshold, it indicates that the first characteristic value of both sets of receivers is in a normal increase state under the same period, and the asphalt in the melting furnace is melting uniformly, indicating that the current furnace temperature meets the melting requirements of asphalt, so the temperature control level is not adjusted.

[0096] If condition ① exists , and The absolute value is greater than the second judgment threshold; ② , and The absolute value is greater than the second judgment threshold; when ① or ② is true, it indicates that uneven stirring may have resulted in a small local area with a higher content of solid asphalt in the melting furnace. The two sets of receivers respond differently to the ultrasonic transmission signal in this local area. In this case, the temperature control level should be set to... Increase the melting speed appropriately.

[0097] when and Both are less than zero and and When the absolute values ​​of all values ​​are greater than the second judgment threshold, it indicates that the first characteristic value is in a decreasing phase, and the proportion of solid asphalt and liquid asphalt in the melting furnace is approaching equilibrium or liquid asphalt is beginning to dominate. At this time, the temperature control level should be set to... This accelerates the melting speed of asphalt.

[0098] when and Both are less than zero and and When the absolute values ​​of all values ​​are greater than the second threshold, the temperature control level will be set to [value]. At this point, the first eigenvalue begins to decay over time until it reaches an equilibrium value, at which point liquid asphalt begins to dominate; at this point, for each set of receivers, for and To proceed with the next stage of assessment.

[0099] If condition ① exists Less than the first judgment threshold and Greater than the first judgment threshold; ② Greater than the first judgment threshold and The value is less than the first judgment threshold; when ① or ② is true, it indicates that the changes in the first characteristic value of the two sets of receivers are different in the same period, indicating that the asphalt in the melting furnace is about to completely melt. At this time, in order to balance the overheating of the melted asphalt and the melting of the unmelted asphalt, the temperature control level is set to .

[0100] when and When all values ​​are greater than or equal to the first judgment threshold, the temperature control level is set to... .

[0101] when and When all values ​​are less than the first judgment threshold, it indicates that the first characteristic value is once again in a normal fluctuation state, the asphalt in the melting furnace is completely melted, and the temperature control level is not adjusted.

[0102] This completes the dynamic adjustment of the melting furnace temperature.

[0103] Step S002: The high-quinoline pitch is subjected to vacuum distillation and cooled to room temperature to obtain the precursor.

[0104] The high-quinoline asphalt was prepared through the above steps. The high-quinoline asphalt was then pulverized and placed in a vacuum distillation reactor. After sealing, a vacuum was first applied to remove air from the container to prevent asphalt oxidation. Heating began when the pressure inside the reactor reached 10-30 mmHg, raising the asphalt to 300°C and maintaining this temperature for 3 hours. After the heating period, nitrogen was introduced to cool the reactor to room temperature, thus obtaining the precursor. In this embodiment, heating began when the pressure inside the reactor was 20 mmHg.

[0105] Step S003: After testing the precursor, grind it into powder and sieve it using different particle sizes.

[0106] The precursor obtained in step S002 was taken out for testing. Then, the precursor was ground using an MQW03 air jet mill with an installed power of 21.8 kW. The powder was then sieved using sieves of different sizes. The particle sizes were D10 = 4-6 μm, D50 = 10-15 μm, and D90 = 25-30 μm.

[0107] In this embodiment, the particle size is D10=6μm, D50=15μm, and D90=30μm.

[0108] At this point, the powder was sieved to different particle sizes.

[0109] Step S004: Place powders of different particle sizes into a mold and press them to obtain a rectangular green embryo.

[0110] The powders of different particle sizes processed in step S003 are evenly placed in a square mold with a rubber sleeve, sealed, and vacuumed for 20 minutes. The mold is then placed in an isostatic press, with the rated working pressure set to 300 MPa. The product is pressed into a rectangular green body of 400*400*200 mm, with a pressure of 120-140 MPa and a density of 1.35-1.40 g / cm³. In this embodiment, the pressure is increased to 120 MPa, resulting in a density of 1.25 g / cm³.

[0111] Thus, a cuboid embryo was obtained.

[0112] Step S005: The rectangular green embryo is roasted to obtain the roasted product.

[0113] The green blanks processed in step S004 are placed in a square iron crucible, covered and filled with metallurgical coke, and fired in a roasting furnace from room temperature to 1000°C for 50 days to produce roasted products.

[0114] At this point, the rectangular raw embryo has been transformed into a baked product.

[0115] Step S006: Grind the calcined product to obtain graphite.

[0116] The calcined product prepared in step S005 is placed in an Atchison-type graphitization furnace, covered and filled with 10-30mm pitch coke / petroleum coke as resistance material, and heated from room temperature to 2800-3000℃ over 12 days to produce graphite. In this embodiment, the pitch coke used is 20mm, and the temperature is raised to 2800℃.

[0117] Thus, graphite was produced.

[0118] It should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

[0119] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. An improved method for the production process of special graphite to enhance the uniformity of asphalt coating, characterized in that, The method includes the following steps: High-quinoline asphalt is prepared by melting modified asphalt and quinoline-insoluble powder in a melting furnace; during the melting process: S1, ultrasonic sensors and two sets of receivers are installed on the melting furnace to collect ultrasonic images; S2, perform multi-scale analysis on the foreground region of the ultrasound image to obtain its texture features, and then combine the pixel values ​​to obtain texture distribution features, including: a preset scale set, using the foreground region of the ultrasound image and the scale set as input to obtain the LBP value of the pixel through the LBP algorithm, and using the average LBP value at different scales as the texture feature of the pixel; calculate the average texture feature of all pixels in the foreground region and obtain its maximum pixel value, and calculate the texture distribution features based on the two; S3, a preset temperature control level, determines two judgment thresholds based on the texture distribution feature values ​​of ultrasonic images before heating to the softening point temperature. Based on different physical states of asphalt, it adjusts the melting furnace temperature by comparing the rate of change of texture distribution feature values ​​in each subsequent cycle and the previous cycle for different receiver groups with the judgment thresholds. Specifically, this includes: The time period during which the melting furnace temperature is raised to the softening point is recorded as the heating time period. All ultrasound images within the heating time period are sorted and numbered according to time, and their texture distribution features are combined into a feature sequence. The feature sequence is fitted with a straight line, and the slope of the fitted line is obtained. The absolute value of the slope is used as the first judgment threshold. A difference sequence of the feature sequence is calculated using a first-order difference algorithm, and the first quartile of the absolute values ​​of all difference values ​​in the difference sequence is used as the second judgment threshold. After the temperature reaches the softening point, for a set of receivers, the slope of the texture distribution feature value of each ultrasound image compared to the adjacent previous ultrasound image is calculated. The slopes of the two sets of receivers are recorded as the first slope and the second slope, respectively. Phase 1: When both the first slope and the second slope are less than or equal to the first judgment threshold, the temperature control level is... ; When either the first slope or the second slope is greater than the first judgment threshold, the temperature control level is: ; When both the first slope and the second slope are greater than the first judgment threshold, the temperature control level is: At this point, the above-mentioned judgment on the ultrasound image is no longer performed, and the second stage of judgment is carried out; Phase Two: When the absolute values ​​of both the first and second slopes are less than the second judgment threshold, the temperature control level is... ; When both the first and second slopes are greater than 0, and the absolute value of one of them is greater than the second judgment threshold, then the temperature control level is... ; When both the first slope and the second slope are greater than 0 and their absolute values ​​are greater than the second judgment threshold, the temperature control level remains unchanged. When either of the following conditions is met: Condition 1: the first slope is greater than 0 and its absolute value is greater than the second judgment threshold, and the second slope is less than 0; Condition 2: the second slope is greater than 0 and its absolute value is greater than the second judgment threshold, and the first slope is less than 0; the temperature control level is [level value missing]. ; When both the first and second slopes are less than 0, and their absolute values ​​are both greater than the second judgment threshold, the temperature control level is [value missing]. At this point, the above-mentioned judgments on the ultrasound images are no longer made, and the third-stage judgment is performed. Phase Three: When either of the following conditions is met: Condition 1: the first slope is less than the first judgment threshold, and the second slope is greater than the first judgment threshold; Condition 2: the first slope is greater than the first judgment threshold, and the second slope is less than the first judgment threshold; the temperature control level is [value missing]. ; When both the first slope and the second slope are greater than or equal to the first judgment threshold, the temperature control level is set to... ; When both the first slope and the second slope are less than the first judgment threshold, no temperature adjustment is performed, and temperature control is completed; the temperature control level ; The high-quinoline pitch was subjected to vacuum distillation and cooled to room temperature to obtain the precursor. The precursors were analyzed and then ground into powder, which was then sieved using different particle sizes. Powders of different particle sizes are placed into a mold and pressed to obtain a rectangular green body; The rectangular green blank is roasted to obtain the roasted product; Graphite is obtained by graphitizing roasted products.

2. The improved method for producing special graphite to enhance the uniformity of asphalt coating as described in claim 1, characterized in that, The obtained high-quinoline asphalt contains 25-30% quinoline insolubles and 70-75% coking value. The softening point of the selected modified asphalt needs to be greater than 110℃.

3. The improved method for producing special graphite to enhance the uniformity of asphalt coating as described in claim 1, characterized in that, The texture distribution features are positively correlated with the entropy values ​​of the pixel texture features in the foreground region, and negatively correlated with the maximum pixel value in the foreground region.

4. The improved method for producing special graphite to enhance the uniformity of asphalt coating as described in claim 1, characterized in that, When high-quinoline asphalt is subjected to vacuum distillation, the pressure inside the distillation reactor is 10-30 mmHg, and the asphalt inside the reactor is heated to 300℃.

5. The improved method for producing special graphite to enhance the uniformity of asphalt coating as described in claim 1, characterized in that, The precursors were sieved to obtain particle sizes of D10=4-6μm, D50=10-15μm, and D90=25-30μm during milling.

6. The improved method for producing special graphite to enhance the uniformity of asphalt coating as described in claim 1, characterized in that, When powders of different particle sizes are placed into a mold and pressed, the pressure range is 120-140 MPa, and the density is 1.35-1.40 g / cm³. 3 .

7. The improved method for producing special graphite to enhance the uniformity of asphalt coating as described in claim 1, characterized in that, When obtaining graphite by graphitizing roasted products, the pitch coke / petroleum coke used is in the range of 10-30mm, and the temperature is increased to 2800-3000℃.

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