Calcination method and intermittent kiln

Abstract

A calcination method and an intermittent kiln belong to the field of inorganic non-metallic material processing. The calcination method includes: obtaining a first reference condition; calcining the processing object, and during the calcination process, continuously collecting and correspondingly obtaining a first working condition; and controlling the calcination condition according to the trigger condition. The scheme can shorten the analysis cycle of the calcination process and improve the analysis quality.

Description

Technical Field

[0001] The present application relates to the field of inorganic non-metallic material processing, and in particular to a calcination method and an intermittent kiln. Background Art

[0002] The preparation or production process of most inorganic non-metallic materials and products requires a high temperature stage (also known as calcination, roasting, firing or sintering), which is also a very important step. The quality of this high temperature calcination process often determines the performance of the final product.

[0003] At present, the evaluation of the high-temperature calcination process of inorganic non-metallic materials and products often adopts the "post-analysis" method. In other words, only after the raw materials or green bodies have been calcined at high temperature and become fired products, can the quality of the high-temperature calcination process be judged by a series of analyses of the products. Such a "post-analysis" method needs to wait until the product test and analysis are completed before it can be carried out. The entire feedback cycle is too long, and it is impossible to timely judge the production process that is undergoing high-temperature calcination, and it is impossible to make timely and necessary adjustments to the high-temperature calcination process that has deviated from the normal state, which can easily cause batch scrapping and increase production costs. Summary of the invention

[0004] The present application proposes a calcining method and a batch kiln for implementing the calcining method.

[0005] The calcination method can analyze the calcination process in progress, thereby obtaining the analysis result faster than post-analysis, so that the operator can control the calcination process in time according to the analysis result.

[0006] The calcination method can provide base parameters by analyzing the calcination process in real time. Then, after the operator selects the appropriate and optimized calcination process control method, the process control and control efficiency in the calcination process can be improved, thereby improving the quality of the calcined product.

[0007] This application is implemented as follows:

[0008] In a first aspect, an example of the present application provides a calcining method for processing an object capable of undergoing a weight change when heated.

[0009] Calcination methods include:

[0010] Obtaining preset conditions corresponding to the calcination process of the processing object; the preset conditions include a first reference condition of the correspondence between the cumulative mass loss of the calcination object and the calcination temperature during the process from the start of calcination to the completion of calcination, and the preset conditions also include initial calcination parameters corresponding to the processing object;

[0011] The initial calcination parameters are set to calcine the processing object, and during the calcination process, the actual mass cumulative loss and the actual calcination temperature of the calcination object are continuously collected, and the corresponding relationship between the actual mass cumulative loss and the actual calcination temperature is obtained as the first working condition;

[0012] The initial calcination parameters are controlled according to a trigger condition, and the trigger condition is determined according to a comparison result of a preset cumulative mass loss amount and an actual mass loss amount corresponding to the same selected calcination temperature point.

[0013] According to some examples of the present application, the trigger conditions include: the preset cumulative mass loss amount is equal to the actual cumulative mass loss amount; or, the actual cumulative mass loss amount is not equal to the preset cumulative mass loss amount; or, the actual cumulative mass loss amount is higher than the preset mass cumulative loss amount by a first preset value upper limit; or, the actual cumulative mass loss amount is lower than the preset mass cumulative loss amount by a first preset value lower limit.

[0014] According to some examples of the present application, the conditions for controlling calcination according to the trigger conditions include: when the actual cumulative mass loss is equal to the preset cumulative mass loss, the initial calcination parameters are kept unchanged and the calcination is continued; or, at a selected calcination temperature point, when the absolute value of the difference between the actual cumulative mass loss and the preset cumulative mass loss is within a preset range, the initial calcination parameters are kept unchanged and the calcination is continued.

[0015] According to some examples of the present application, the conditions for controlling calcination according to the trigger conditions include: at a selected calcination temperature point, when the actual mass cumulative loss amount is higher than the preset mass cumulative loss amount by a first preset value upper limit that is greater than the preset mass cumulative loss amount, stopping the calcination; or, at a selected calcination temperature point, when the actual mass cumulative loss amount is lower than the preset mass cumulative loss amount by a first preset value lower limit that is less than the preset mass cumulative loss amount, maintaining the selected calcination temperature point for a selected time, and stopping the calcination when the actual mass cumulative loss amount is still less than the first preset value lower limit after exceeding the selected time or exceeding a maximum set time greater than the selected time; or, at a selected calcination temperature point, when the actual mass cumulative loss amount is lower than the preset mass cumulative loss amount by a first preset value lower limit that is less than the preset mass cumulative loss amount, reducing the calcination heating rate until the next selected calcination temperature point, and when the next selected calcination temperature point is reached, the actual mass cumulative loss amount is still less than the second preset value lower limit of the actual mass cumulative loss amount corresponding to the next selected calcination temperature point, stopping the calcination.

[0016] According to some examples of the present application, the conditions for controlling calcination according to the trigger conditions include: at a selected calcination temperature point, when the actual mass cumulative loss is lower than the preset mass cumulative loss by a first preset value lower limit that is less than the preset mass cumulative loss, maintaining the selected calcination temperature point for a selected time until the actual mass cumulative loss is greater than the first preset value lower limit, heating up, and calcining according to the parameters after the selected calcination temperature point with the initial calcination parameters set; or, at a selected calcination temperature point, when the actual mass cumulative loss is lower than the preset mass cumulative loss by a first preset value lower limit that is less than the preset mass cumulative loss, reducing the calcination heating rate until the next selected calcination temperature point, and when the next selected calcination temperature point is reached, when the actual mass cumulative loss is greater than the second preset value lower limit of the actual mass cumulative loss corresponding to the next selected calcination temperature point, continuing to maintain the set initial calcination parameters from the next selected calcination temperature point.

[0017] According to some examples of the present application, when the processing object is heated, the weight changes and gas is generated, and the preset conditions also include a second reference condition of the correspondence between the preset concentration of the gas and the calcination temperature; the calcination method also includes: during the calcination process, continuously collecting the correspondence between the actual concentration of the gas in the calcination environment and the actual calcination temperature as the second working condition; the trigger condition is determined based on the comparison result of the preset mass cumulative loss amount and the actual mass cumulative loss amount corresponding to the same selected calcination temperature point, and the comparison result of the preset concentration of the gas corresponding to the same selected calcination temperature point and the actual concentration.

[0018] In a second aspect, an example of the present application provides a batch kiln for implementing the above-mentioned calcination method to produce inorganic non-metallic materials and products thereof.

[0019] Batch kilns include:

[0020] The furnace body comprises a furnace cavity which is enclosed by a furnace wall, a furnace top and a furnace bottom to provide a calcining space, wherein the furnace wall is provided with a furnace door for opening and closing the furnace cavity, the furnace wall and the furnace top are cooperatively connected, and the furnace bottom is opposite to the furnace top and cooperatively connected to the furnace wall;

[0021] A heater installed in the furnace body, used to provide heat to the furnace cavity for calcination;

[0022] The temperature sensor installed in the furnace body is used to detect the calcination temperature conditions in the furnace chamber;

[0023] The weighing meter is used to continuously detect the weight of the calcining object placed in the furnace chamber.

[0024] According to some examples of the present application, a batch kiln includes a gas monitor for detecting the concentration of a selected gas in a furnace chamber; and the furnace bottom and the furnace wall cooperate with each other through a curved sealing groove.

[0025] According to some examples of the present application, the furnace body is configured with an air inlet pipe and an exhaust pipe, and the gas monitor is arranged on the exhaust pipe; and / or, the furnace bottom includes a support frame and a refractory layer for placing the calcination object, and the refractory layer is located on the support frame.

[0026] According to some examples of the present application, the intermittent kiln includes a column, a weighing meter is in contact with the furnace bottom through the column, the furnace bottom and the furnace wall are in gap, and the furnace bottom can freely move a given distance from the furnace top to the furnace bottom, the weighing meter is in contact with the furnace bottom through the column outside the furnace cavity, and the weighing meter detects the weight of the calcined object placed on the furnace bottom through the free movement of the furnace bottom;

[0027] Alternatively, the intermittent kiln includes a horizontal column for placing the calcined object, the horizontal column passes through the furnace wall and can move freely a given distance from the furnace top to the furnace bottom, the furnace bottom is tightly matched with the furnace wall, and a weighing meter cooperates with the horizontal column outside the furnace cavity and detects the weight of the calcined object placed on the furnace bottom through the free movement of the horizontal column.

[0028] In the above implementation process, the calcination method provided in the embodiment of the present application monitors the calcination process through the temperature and the calcination mass loss according to the characteristics of the chemical reaction or physical change of the processing object during the calcination process, so as to effectively feedback the condition parameters in the calcination process, so as to select the corresponding calcination process control method, thereby improving the calcination efficiency and quality.

[0029] The calcination method implemented by the intermittent kiln of the present application can measure the changes directly related to the calcination object in real time during the calcination process, realize the in-process analysis of the high-temperature calcination process, thereby quickly and deeply analyzing the calcination process, shortening the analysis cycle and improving the quality of the analysis, and then controlling the quality of the calcined product.

[0030] During the high-temperature calcination process, by monitoring the weight change of the calcination object (and further including the change in the concentration of specific gases in the kiln), different calcination processes can be analyzed and compared more quickly and deeply, improving the speed and quality of process development. By using the law of the weight change of the calcination object under high-temperature calcination to adjust and control the calcination process in real time, the risk of the calcination process deviating from the target can be reduced, and the yield of the product can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 The schematic diagram of the existing analytical scheme for the calcination process;

[0033] Figure 2 A schematic block diagram showing the in-process analysis of the calcination process in the example of the present application is shown;

[0034] Figure 3 It is a structural schematic diagram of the first intermittent kiln in the example of this application at a first viewing angle;

[0035] Figure 4 It is a structural schematic diagram of the first intermittent kiln in the example of this application at a second viewing angle;

[0036] Figure 5 It is a structural schematic diagram of the second intermittent kiln in the example of this application at a first viewing angle;

[0037] Figure 6 It is a structural schematic diagram of the second intermittent kiln in the example of this application at a second viewing angle;

[0038] Figure 7 The figures are the temperature rise curves under four different processes in the calcination process analysis exemplified in this application.

[0039] Icons: 1a-first wall; 1b-second wall; 1c-third wall; 2a-furnace door; 3a-furnace roof; 5-metal frame; 6-refractory material; 7a-calcination object; 8a-metal frame; 9-column; 10a-weighing sensor; 14-wire; 15-weighing instrument; 16-mounting bracket; 17a-electric heater group; 18-curved sealing groove; 50-gas collection pipe; 55a-exhaust pipe; 900-thermocouple; 901-intake Tube; 1d-the fourth wall; 1f-the fifth wall; 3b-the second furnace top; 4b-the second furnace bottom; 7b-the second calcination object; 8b-the second metal frame; 10b-the second weighing sensor; 17b-the heating rod; 17c-the second heating rod; 30-the ceramic rod; 32-the opening; 35-the metal support; 36-the supporting platform; 41-the supporting wheel; 42-the shaft; 43-the supporting bracket; 50b-the second gas collection pipe; 55b-the second exhaust pipe. DETAILED DESCRIPTION

[0040] For inorganic non-metallic powder materials, the calcined powder products are generally analyzed for relevant physical and chemical indicators, such as particle size, loose density, etc. Alternatively, there are some solutions that test some characteristics related to product applications. For example, for lithium battery positive electrode materials, some electrochemical tests are often performed on the materials after high-temperature calcination to obtain some indicators of electrochemical properties, such as capacity, cycle, etc. This is a post-analysis solution, and it is also a compromise that must be chosen in the absence of better available solutions. Figure 1 As shown, the current method used is as follows Figure 1 The post-analysis scheme shown. The inventor believes that the process has the following characteristics: the raw materials are the input of the high-temperature calcination process; the key process parameters (such as temperature, process gas flow, furnace pressure and other parameters) are process control factors and are also the input of high-temperature calcination. The only output of this process is the product. Therefore, the evaluation of this process can only be based on the evaluation (testing) of the product, that is, "post-analysis".

[0041] Different from the above-mentioned post-analysis solution, the inventors proposed a better in-process analysis (such as Figure 2 In this analysis scheme, the key process output indicators in the high-temperature calcination operation refer to one or several important physical or chemical properties of the calcination object (inorganic non-metallic materials or products) during the calcination process. These properties will change significantly during the high-temperature calcination process; and these changes are directly related to the high-temperature calcination process (such as calcination temperature or time or heating rate, etc.). And these changes in the calcination object during the high-temperature calcination process can be measured.

[0042] Therefore, a key to the present application is to find a practical solution to measure and collect key process output information directly related to the changes in the calcination object itself on high-temperature calcination industrial equipment.

[0043] The inventors of the present application have found through analysis that many inorganic non-metallic materials usually involve weight changes during high-temperature calcination. Therefore, during high-temperature calcination, the weight of these materials will change with the calcination temperature and time, and the proportion of this weight change is directly related to the degree of reaction. Then, from the weight change of the calcined object, the progress of the reaction of the calcined object can be inferred. In addition, factors related to weight change may also include changes in the atmosphere in the kiln. If the gas content in the kiln can be measured, the degree of reaction can also be inferred based on the principle of chemical reaction. This method of determining the content of a specific gas can be used alone or in conjunction with the aforementioned method of monitoring weight changes. Therefore, after collecting data on product weight changes or changes in the concentration of a specific gas inside the kiln, technicians can analyze the collected process output data based on the principle that the calcined object reacts at high temperature, judge the degree of reaction, and accordingly infer the "pros and cons" of the ongoing high-temperature calcination process.

[0044] As a specific alternative example, the analysis is as follows: Calcite (CaCO3) theoretically decomposes at 930°C to produce calcium oxide (CaO) and carbon dioxide (CO2), and the weight will drop by 44% accordingly. If the weight of the calcined object calcite is monitored in large-scale production, it is found that the weight begins to drop at 930°C, and after 3 hours of heat preservation, the weight drops by about 44%, and remains basically stable as the calcination time increases. It can be judged that the decomposition of calcite is basically completed as expected, and calcium oxide is generated. However, if it is found that the weight does not change at around 930°C, and the weight does not start to decrease until the temperature rises to 1000°C. It is possible that the actual measured temperature of the calcining kiln has a large deviation from the displayed temperature, and the temperature measurement system of the kiln needs to be calibrated in time; or other impurities are mixed in the raw materials. In addition, technicians can also use this method to judge different calcination processes and select a more reasonable calcination process.

[0045] Therefore, the present application scheme can collect and integrate the data of key process output indicators of these batches after industrial production of high-temperature calcination of multiple batches of the same material or product, and then combine other data of these batches (such as product test data, etc.), so that technicians can analyze and screen to obtain a more ideal "standard" change curve of weight or gas concentration in the calcination process. Unlike the data collected on small-scale experimental equipment in the laboratory (such as a thermogravimetric analyzer), this "standard" curve is obtained on industrial-scale production equipment, and is therefore more suitable for high-temperature calcination processes in industrial production.

[0046] After obtaining such a "standard" curve, technicians can compare the curve collected in each subsequent high-temperature calcination process with the "standard" curve, so as to make real-time judgments on the ongoing high-temperature calcination process.

[0047] If it is found that the weight change and / or gas concentration change of the ongoing high-temperature calcination process begins to deviate (or deviate to a certain extent) from the "standard" curve, the technician can adjust the process input factors (such as temperature, gas flow, etc.) in time to make the weight change curve and / or gas concentration change curve return to or approach the "standard" curve. In other words, the high-temperature calcination process can be controlled and adjusted in real time through the above operation method. Of course, the role played by the technician can also be replaced by the automation system, making the entire data collection, analysis, and feedback control an intelligent and automated process.

[0048] Calcination process analysis

[0049] The positive electrode material of lithium-ion batteries, ternary material Li(Ni 0.5 Co 0.2 Mn 0.3 )O2 (abbreviated as 523 ternary material) as an example, the analysis of the high-temperature calcination process using weight and gas monitoring is explained.

[0050] The raw material lithium carbonate (Li2CO3) and 523 precursor [nickel cobalt manganese hydroxide (Ni 0.5 Co 0.2 Mn 0.3 )(OH)2], after being uniformly mixed in a molar ratio of lithium to transition metal of 1.03:1, it is calcined at high temperature according to a certain process to form a 523 ternary material.

[0051] According to the reaction principle and experimental analysis, two thermal decomposition reactions and one oxidation reaction will occur during the synthesis process. The 523 precursor in the mixed raw material undergoes a decomposition reaction between 250-350°C, and the reaction formula is as follows: (NiCoMn)(OH)2→(NCM)O+H2O.

[0052] The lithium carbonate in the mixed raw materials undergoes a decomposition reaction at 350-750°C, and the reaction formula is as follows:

[0053] Li2CO3→Li2O+CO2↑.

[0054] In addition, after the temperature is higher than 450 ° C, the lithium oxide Li2O produced by the decomposition of lithium carbonate begins to undergo the following oxidation reaction with transition metal oxide (NCM) O and oxygen:

[0055] 0.5Li2O+(NCM)O+0.25O2→Li(NCM)O2.

[0056] Combining the decomposition and oxidation reactions, the reaction occurring during the high temperature calcination process can be represented by the following overall reaction formula: (NiCoMn)(OH)2+0.5Li2CO3+0.25O2→Li(NCM)O2+H2O↑+0.5CO2↑.

[0057] According to the results of laboratory thermal analysis of trace samples (sample weight less than 1 gram, calcined in air atmosphere, heated from room temperature to 900°C, heating rate 5°C / min), the weight change law of the mixed raw materials during high temperature calcination is summarized as follows:

[0058] From room temperature to 350°C, the free water in the mixed raw materials volatilizes and the precursor decomposes completely. The weight loss percentage of the sample in this temperature range is 14.1±1%. From 350°C to 500°C, part of the lithium carbonate decomposes. The weight loss percentage of the sample in this temperature range is 12.8±1%. From 500°C to 750°C, the remaining lithium carbonate continues to decompose until it is completely decomposed.

[0059] In addition, the above oxidation reaction also begins to occur in this temperature range (350-750℃), and the sample weight loss percentage is 4.2±1%. From 750℃ to 900℃, the high temperature will cause a small amount of lithium oxide in the sample to volatilize, and the sample weight loss percentage in this temperature range is 0-1.9%. Since the amount of sample used in the test is very small, it can be considered that this weight change law reflects the relatively ideal high-temperature calcination process of 523 ternary material.

[0060] In addition, the experiment also found that if the decomposition reaction of the precursor or lithium carbonate in the raw material is not completely completed at a relatively low temperature and rises to a higher temperature, the residual undecomposed raw materials will affect the oxidation reaction occurring at a higher temperature, thereby causing a negative impact on the quality and performance of the 523 ternary material generated by the reaction, such as too low initial specific capacity and / or poor cycle performance.

[0061] Therefore, an ideal high temperature calcination process for 523 ternary materials should at least meet the following requirements:

[0062] 1. From room temperature to 350°C, the ternary precursor is completely decomposed;

[0063] 2. 350 to 500°C, lithium carbonate decomposes as much as possible;

[0064] 3. 500 to 750°C, lithium carbonate decomposes completely;

[0065] 4. 750 to 900°C, the loss of lithium oxide by volatilization is as small as possible;

[0066] 5. Under the premise of ensuring that the above requirements are met, the entire calcination process time is as short as possible (to improve production efficiency).

[0067] According to the conditions of the pilot experiment (air atmosphere, heating rate 5°C / min), the researchers designed four different mass production high-temperature calcination processes for 523 ternary materials (see Table 1). The main difference between them is that the heating rates in the heating stage are different (see Figure 7 ). For the convenience of comparison, the holding time and cooling time of the four processes are kept the same.

[0068] Table 1

[0069]

[0070] The analysis and comparison of the above four high-temperature calcination processes used a calcination kiln. 64 saggers were placed in the furnace. Each sagger was loaded with 7 kg of a mixture of 523 precursor and lithium carbonate (the molar ratio of lithium to transition metal was 1.03:1), and the total weight of the material was 448 kg. Each sagger weighed 8 kg, totaling 512 kg. The total weight of the furnace bottom and support platform was 404 kg. Therefore, before calcination, the total weight carried on the weight sensor was 1364 kg. The kiln used 4 weight sensors, and the measurement accuracy of the weight monitoring system was 0.1%, that is, 1.364 kg. From the material weight change results of the four high-temperature calcination process comparison experiments, the weight loss percentages when the furnace chamber temperature reached 350, 500, 750, and 900 ° C (the first temperature point entering the insulation zone) were read respectively, see Table 2. In addition, the weight loss percentages of each temperature section obtained in the laboratory test results were used as reference standards and are also listed in the last column of Table 2.

[0071] Table 2

[0072]

[0073]

[0074] In Table 2, RT means room temperature.

[0075] As can be seen from Table 2, the weight loss percentage of process 1 at 350°C is much lower than the reference standard. This is because the kiln temperature rises too fast and the heat is not fully transferred to the material in the sagger, so the actual temperature of the material in the sagger is much lower than the temperature of the furnace chamber, resulting in the decomposition reaction of the precursor not being complete when the temperature in the furnace chamber reaches 350°C, and the weight loss is much less than expected. The weight loss of process 1 at 350-500°C is within the reference standard. This is because the precursor that has not been decomposed below the furnace chamber temperature of 350°C continues to decompose at 350-500°C, and the decomposition of lithium carbonate is carried out simultaneously, and the weight loss of the two is superimposed. The weight loss percentage of process 1 at 500-750°C and 750-900°C is greater than the reference standard. This is also because when the furnace chamber temperature reaches 500°C and 750°C, the decomposition of lithium carbonate is not sufficient, so the undecomposed lithium carbonate continues to decompose at a higher temperature, resulting in a large weight loss in these two temperature sections. Therefore, process 1 is not suitable for the high-temperature calcination process of 523 ternary materials on a mass production scale.

[0076] Process 2 reduces the heating rate to 3.33℃ / min. When the temperature reaches 350 and 500℃, the weight loss percentage of the material is within the reference standard, indicating that the heating rate in the temperature range below 500℃ is reasonable. However, when the temperature reaches 750℃, the weight loss percentage is lower than the reference standard, while the weight loss percentage at 900℃ is higher than the reference standard. This result shows that the heating rate of process 2 above 500℃ is still too fast, resulting in incomplete decomposition of lithium carbonate.

[0077] Process 3 has the lowest heating rate, which is 1.67°C / min, and the weight loss percentages recorded at all temperature points are within the reference range. This shows that the heating rate of the entire heating section of process 3 is appropriate. However, process 3 also has the longest heating time and the lowest efficiency.

[0078] The heating rate of process 4 below 500°C is the same as that of process 2, which is 3.33°C / min, and the heating rate above 500°C is the same as that of process 3, which is 1.67°C / min. From the weight loss percentage recorded at each temperature point, it is within the reference range. This shows that the two-stage heating rate setting of process 4 is also reasonable, and the heating time is less than that of process 3, which has higher production efficiency.

[0079] At the same time, the gas in the furnace cavity was analyzed. The exhaust gas discharged from the furnace cavity was drawn out from the exhaust main pipe, and the carbon dioxide in the exhaust gas was qualitatively analyzed (it can only determine whether it exists, not how much). The air intake and exhaust volume of the kiln are set to change the air every 8 minutes (to replace all the gas in the furnace cavity). The results of the gas analysis are shown in Table 3.

[0080] Table 3

[0081] Temperature point Process 1 Craft 2 Craft 3 Craft 4 350℃ none none none none 500℃ none have have have 750℃ have have none have 900℃ have have none none

[0082] As can be seen from Table 3, at 900°C, process 1 and process 2 can still detect the presence of carbon dioxide in the exhaust gas discharged from the furnace chamber, which shows that lithium carbonate is not completely decomposed below 750°C, and the decomposition reaction of the residual lithium carbonate continues until 900°C. This confirms the above judgment through the analysis of weight change: the heating rate of process 1 and process 2 above 500°C is too fast. However, at 900°C, no carbon dioxide was found in processes 3 and 4, indicating that lithium carbonate has been completely decomposed. Process 4 can still detect carbon dioxide at 750°C. Because this analysis is a qualitative analysis, the detected carbon dioxide may be a trace amount, and the decomposition reaction of lithium carbonate is likely to be nearing its end at this time.

[0083] The 523 ternary materials synthesized by the four processes were used as positive electrode materials, assembled with metal lithium negative electrode, separator and electrolyte into button test batteries, and the electrochemical properties of the positive electrode materials synthesized by different processes were tested and compared. The test results are shown in Table 4. It can also be seen from Table 4 that the electrochemical test results of the 523 ternary positive electrode materials synthesized by process 3 and process 4 are the best, while the electrochemical properties of the ternary materials synthesized by process 1 and process 2 are poor. From the perspective of product application testing, it is proved that process 3 and process 4 are suitable high-temperature calcination processes. Based on the above analysis, the final mass production process adopts the two-stage heating rate setting of process 4 to achieve the best balance between product performance and production efficiency.

[0084] Table 4

[0085]

[0086] In summary, based on the above experimental analysis, the method of extracting material weight changes and analyzing specific gases during the calcination process can help technicians analyze and screen high-temperature calcination processes on a mass production scale, further improve the efficiency of process development, and shorten the development cycle.

[0087] The calcination method in the examples of the present application and the equipment used to implement the calcination method will be described below in conjunction with the embodiments.

[0088] In the examples of this application, an intermittent box furnace is used as an example to illustrate the calcination method and equipment. However, it should be pointed out that the calcination method and equipment can be appropriately modified to be applicable to other types of intermittent kilns, such as shuttle kilns, bell furnaces, etc. That is, the aforementioned calcination method is applicable to various intermittent kilns. Other types of continuous kilns can also be adapted to the calcination method through modification based on the principles of this application.

[0089] Calcination equipment

[0090] See also Figure 3 and Figure 4 , showing the first intermittent box furnace.

[0091] The intermittent box furnace includes a furnace body, which serves as the installation basis for various equipment in the calcining operation and provides sufficient installation space and position.

[0092] The furnace body is generally a box-type structure, which has a furnace wall, a furnace roof 3a and a furnace bottom. In order to improve the durability of the box-type furnace, the main part of the box-type furnace can be wrapped with a metal frame 8a (carbon steel or stainless steel), and the metal frame 8a plays a supporting role for the box-type furnace structure built with refractory bricks.

[0093] Furthermore, a supporting structure may be configured under the box-type furnace as required, so as to reserve space under the box-type furnace for placing the weighing sensor mentioned later. For example, a bracket 16 is installed under the metal frame 8a of the box-type furnace to lift the box-type furnace as a whole off the ground, leaving enough space for placing the weighing sensor. Alternatively, in other examples, a pit is set on the ground, and the weighing sensor is placed in the pit. The placement method can be flexibly selected according to the conditions of the production site.

[0094] Furthermore, considering that the calcination process may require the introduction of raw material gas (for example, oxygen, nitrogen or a mixed gas, etc.), and that waste gas or other gases that need to be discharged may be generated during the calcination process, the furnace body may also be optionally equipped with an air inlet pipe 901 and an exhaust pipe 55a; both may be optionally connected to the furnace body, for example, by penetrating and fixing them on the furnace wall.

[0095] In the furnace body, the furnace top and the furnace bottom are connected to the furnace wall respectively, thereby forming a space for retaining the calcined object, for example, called a furnace chamber. Considering the atmosphere that may be required or generated during calcination, the furnace chamber is generally constructed in a relatively sealed manner.

[0096] As the name implies, the furnace top and furnace bottom in the furnace body are generally opposite to each other, and according to their general use and construction, the two are opposite to each other in the vertical direction.

[0097] As a passage for the calcined object to enter the furnace body, the furnace wall is connected to the furnace door 2a. The furnace door is arranged in a movable manner so as to be opened and closed. In other words, the furnace wall has an opening connected to the furnace cavity, and the furnace door is connected to the furnace wall at the opening, and can be operated such as moving to achieve the closure or exposure of the opening. Among them, the furnace wall can include three walls, for example, recorded as the first wall 1a, the second wall 1b and the third wall 1c. The three walls constituting the furnace wall, together with the furnace door, form a four-sided enclosure structure. The furnace roof can be a dome-shaped arched structure, which can increase the internal space of the furnace cavity.

[0098] Since high-temperature calcination operations may be involved, the furnace walls, furnace roof and furnace door can be built with lightweight refractory bricks, and the outside can be insulated with fibrous materials with low thermal conductivity such as aluminum silicate ceramic fiber or rock wool.

[0099] In the furnace body, the furnace bottom has different options depending on the device for measuring the weight of the calcined object (hereinafter referred to as a weighing meter / weighing sensor 10a).

[0100] For example, in some examples (such as the first example), the weighing device can measure the weight through the furnace bottom, such as Figure 3 and Figure 4 In other examples (such as the second example), the weighing device does not weigh through the furnace bottom, but weighs through other holding devices for placing the calcined objects, such as Figure 5 and Figure 6 shown.

[0101] Therefore, in the first example, the structure of the furnace bottom can be constructed as a metal frame 5 (such as cast iron or stainless steel) with one or more layers of refractory material 6 laid on it. The refractory material can form a closed high-temperature calcining space with the furnace wall, the furnace roof 3a and the furnace door 2a, and at the same time serve as a supporting platform for carrying the calcining object 7a. In other words, in such an example, the furnace bottom includes a support frame and a refractory layer for placing the calcining object, and the refractory layer is located on the support frame.

[0102] Furthermore, in order to be able to weigh the weight of the object to be calcined, the furnace bottom 4a is separated from the furnace wall and the furnace door 2a. In this way, there is a gap between the furnace bottom and the furnace wall, so that the furnace bottom can move freely from the furnace top to the furnace bottom. Therefore, the gravity of the furnace bottom and the object to be calcined thereon can be transmitted downward.

[0103] As an example, a recessed structure is provided at the lower part of the furnace door and the furnace wall to form a curved sealing groove 18. The furnace door and the furnace wall form a curved sealing structure that matches with the furnace bottom. The recessed structure of the curved sealing groove 18 can be embedded in the refractory material layer that forms a convex structure of the furnace bottom. The refractory material layer of the furnace bottom has a convex structure. The convex structure can be embedded in the curved sealing groove 18. Among them, the cross-section of the curved sealing groove can be a U-shaped structure. Of course, the curved sealing groove can also be two or more continuous U-shaped structures or W-shaped structures. The convex structure of the refractory material layer of the furnace bottom that is equal to it is correspondingly increased or changed to match it.

[0104] By constructing the furnace bottom in the above manner, the curved seal structure blocks the high temperature in the furnace cavity from being transmitted to the lower part of the furnace bottom, so that the space below the furnace bottom forms a low-temperature zone; the temperature of this space can usually be kept below 60°C, and metal parts can be used normally. Moreover, based on this, the weighing scale does not need a high-temperature resistant structure design.

[0105] In the first example, the weighing meter can be in contact with the furnace bottom through the column 9 outside the furnace cavity, so that the weighing meter detects the weight of the calcined object placed on the furnace bottom through the free movement of the furnace bottom (moving downward under gravity or having a tendency to move downward). One end of the column is fixedly connected to the furnace bottom, and the other end of the column is connected to the weighing meter. When the kiln is provided with a metal frame 8a, the column passes through the metal frame 8a (in the second example, the second metal frame 8b, such as Figure 5 As shown). Furthermore, the weight information collected by the weighing meter is connected to the weighing instrument through the wire 14, and the weighing instrument 15 collects the signal from the weighing sensor 10a and transmits it to the human-machine interface through the PLC for real-time display, or transmits it to the control system to display and store the collected weight data, and the historical data can be checked at any time or compared with the previous data.

[0106] In addition, in the second example, the furnace wall, the second furnace top 3b, and the second furnace bottom 4b of the furnace body are respectively built with refractory bricks. Moreover, the furnace bottom and the furnace wall are an integrated structure, that is, the furnace bottom and the furnace wall are closely matched, see Figure 5 and Figure 6 Therefore, in such an example, the kiln is not equipped with a curved seal structure. Since the furnace bottom cannot obtain the weight of the calcined object, the second weighing sensor 10b does not weigh the calcined object through the furnace bottom in this example.

[0107] In order to carry out weighing, in the structure of the second example, the furnace wall is provided with a heat-resistant supporting structure, such as a ceramic rod 30 / silicon carbide ceramic rod, or it can also be called a cross column. The two ends of the ceramic rod pass through the furnace wall (the fourth wall 1d and the fifth wall 1f), and the two ends are gap-matched with the furnace wall in the vertical direction. The gap-matching method is, for example, that the furnace wall is provided with an opening 32, and its diameter is greater than the outer diameter of the ceramic rod. Through such a structural design, the cross column can freely move a given distance from the furnace top to the furnace bottom. Since the furnace wall has an opening, high-temperature resistant ceramic fiber can be filled in it to prevent the high temperature in the furnace cavity from being conducted outward through the gap.

[0108] The calcined object placed on the ceramic rod can be recorded by a weighing meter matched with the ceramic rod. In other words, the weighing meter can be matched with the crossbar outside the furnace cavity and detect the weight of the calcined object placed on the furnace bottom through the free movement of the crossbar.

[0109] Exemplarily, the two ends of the ceramic rod pass through the fourth wall 1d and the fifth wall 1f on both sides and are placed on the support bracket 43 outside the furnace walls on both sides. These ceramic rods 30 can carry the second calcination object 7b. The diameter, number and distance between the ceramic rods 30 can be selected according to the size, weight and calcination process of the second calcination object 7b. In the illustrated structure, outside the box furnace, the two ends of the ceramic rod are placed on the support wheel 41; and the support wheel 41 is installed on the support bracket 43 through the shaft 42. The support wheel can rotate freely around the shaft. Such an arrangement allows the ceramic rod 30 to rotate freely, so as to facilitate the calcined material to be placed in or taken out of the box furnace (small rolling friction).

[0110] Considering that the calcination process may involve high temperatures, the temperature of both ends of the ceramic rod will be relatively high (over 100° C.). Therefore, the material of the support wheel can be a heat-resistant material with low thermal conductivity, such as ceramic materials such as corundum.

[0111] The support brackets 43 on both sides of the box-type furnace are respectively connected to the metal pillars 35 for support. The bottom of the metal pillars is provided with a second weighing sensor 10b. The second weighing sensor 10b is placed on a supporting platform 36 outside the furnace body.

[0112] In addition to the above structure, the box furnace also has a heater as a device for providing heat to calcine the object to be processed. Figure 3 and Figure 4 The electric heater group 17a is selected in the structure shown. The heater is connected to the furnace body. According to the placement of the calcined object in the furnace chamber, the electric heater group 17a can have different configurations. For example, when the calcined objects are arranged vertically in the furnace chamber, the electric heater group 17a can be vertically arranged near the furnace wall on both sides of the furnace chamber. The number and length of the electric heaters can be selectively designed according to the size of the box furnace and the requirements of the calcination process. Figure 5 and Figure 6 In the structure shown, the kiln is equipped with electric heaters, such as a heating rod 17b and a second heating rod 17c, and these heating rods are located on the upper and lower sides of the ceramic rod, and both ends also pass through the furnace body.

[0113] In addition to electric heaters, fuel heating can also be selected according to the requirements of the calcination object and the calcination process. Therefore, in such an example, the heater can be a combustion heating device, which can spray fuel through a nozzle and other components - the fuel can be heavy oil, coal powder, natural gas, etc. - to provide heat through combustion. In other examples, the heater can also be a fuel heating method with a heat radiation tube. In addition, as a device for detecting the calcination temperature conditions in the furnace chamber, the kiln has a temperature sensor connected to the furnace body.

[0114] In addition, in addition to configuring a weighing sensor to monitor the weight of the calcination object in the calcination process in real time and continuously, it is also possible to monitor the atmosphere generated by the calcination object during the calcination process, so as to monitor and / or analyze the calcination process in conjunction with the detected weight data. Accordingly, the intermittent kiln can be equipped with a gas monitor for detecting the concentration of the selected gas in the furnace chamber. Exemplarily, the gas monitor is arranged on an exhaust pipe for discharging exhaust gas on the furnace wall of the furnace body. In some examples, the aforementioned selected gas, for example, mainly refers to the gas generated by the calcination object being calcined.

[0115] The gas monitor can be a commercially available device. As an example, the gas monitor can mainly include a gas collection tube, a gas pipeline, a dust collector and a condenser, a vacuum pump and a gas analyzer. Its main working method is: under the negative pressure of the vacuum pump, the gas in the exhaust pipe enters the gas collection tube. Then, the gas enters the dust collector through the gas pipeline to remove dust in the exhaust gas. Then it enters the condenser through the gas pipeline to remove moisture in the exhaust gas. Then the exhaust gas enters the vacuum pump through the gas pipeline. Since the sampling volume does not need to be large, the vacuum pump can use a low-flow gas pump, such as a peristaltic pump. The gas is transported by the vacuum pump and enters the gas analyzer through the gas pipeline. The gas analyzer can choose different types according to the different analysis objects - oxygen, carbon dioxide, or nitrogen oxide analyzers, or laser spectrometers that can analyze the concentrations of multiple gases. After the gas analyzer analyzes the collected gas, the collected signal is transmitted to the human-machine interface through the PLC for real-time display, or transmitted to the control system to display and store the collected weight data. The historical data can be checked at any time or compared with previous data.

[0116] The above content is a brief description of the gas monitor. The attached drawings only show the gas collection tube, and other structures can be implemented by solutions known to those skilled in the art.

[0117] In order to avoid interference from the atmosphere in the furnace cavity, the gas monitor can collect gas from the exhaust pipe of the kiln to reflect the average state of the gas in the entire kiln, without inaccurate measurement results caused by uneven gas distribution in the furnace cavity. And there is no need to drill holes in the furnace wall of the box-type furnace, which is simpler and easier to implement.

[0118] In other examples, the gas collection pipe can also be set on the furnace wall of the box-type furnace to directly collect the gas in the furnace cavity. For example, the gas collection pipe passes through the refractory bricks and insulation layer of the furnace wall. At the same time, ceramic fiber is selected to be inserted into the gap between the collection pipe and the refractory material and the insulation material to prevent the heat in the furnace cavity of the box-type furnace from being transferred to the outside of the box-type furnace through this gap. When the gas collection pipe is set on the furnace wall, it is necessary to ensure that the pipe mouth of the gas collection pipe avoids areas where the gas flow in the furnace cavity is slow or stagnant, such as corners of the furnace cavity. At the same time, the pipe mouth of the gas collection pipe should be kept as far away as possible from areas such as Figure 3 The gas injection port of the air intake pipe 901 shown in the figure prevents the actual gas concentration in the furnace chamber from being unable to be accurately measured due to interference from the air intake.

[0119] exist Figure 3 and Figure 4 In the structure shown, the exhaust pipe 55a is arranged on the furnace wall of the furnace body, and the gas collection pipe 50 is connected to the exhaust pipe 55a. Figure 5 and Figure 6 In the structure shown, the second exhaust pipe 55b is arranged on the second furnace roof 3b of the furnace body, and the second gas collection pipe 50b is also connected to the exhaust pipe 55a accordingly. The gas collection pipe can be made of high temperature resistant material, such as ceramic or stainless steel. The material of the gas collection pipe 50 can be selected according to the maximum working temperature and working atmosphere environment (oxidation, reduction, corrosive, etc.) of the box-type furnace.

[0120] Calcination method

[0121] Based on the above analysis of calcination equipment and calcination process, the high temperature calcination process of 523 ternary material is controlled.

[0122] According to the above analysis of the calcination process, the weight loss standard of the mass production batch was formulated. In addition, in order to facilitate the control method, the cumulative weight loss (i.e., the weight loss calculated based on the initial weight at room temperature) was used, as shown in Table 5.

[0123] Table 5

[0124]

[0125] WL min (i) Minimum cumulative weight loss percentage; WL max (i) represents the maximum value of the cumulative weight loss percentage.

[0126] Therefore, based on the data in Table 5, the newly carried out 523 ternary material calcination process is adjusted and controlled as follows:

[0127] 1. When the weight loss percentage WL(i) of a batch of calcination process at a specified temperature point T(i) meets WLmin (i)≤WL(i)≤WL max (i), it indicates that the calcination process meets expectations and the original process regime continues to be implemented until the next specified temperature point T(i+1).

[0128] 2. When the weight loss percentage WL(i) of a batch of calcination process at a specified temperature point T(i) is lower than the mass production standard WL min (i) indicates that the decomposition reaction is not sufficient at this time. The control of the calcination process can be adjusted according to the following scheme:

[0129] Method 1: Keep the furnace chamber temperature at this temperature point T(i) for a period of time t, and wait until the weight loss percentage WL increases to meet the mass production standard WL ≥ WL min (i) Then continue to increase the temperature and continue to implement the original process system. In addition, set the maximum time t max If the weight loss percentage WL does not enter the standard range within the set time, the calcination process is immediately interrupted and cooled. After the kiln and materials are cooled to room temperature, the materials and equipment are checked.

[0130] Method 2: Reduce the heating rate from this temperature point T(i) to the next temperature point T(i+1) (for example, reduce it to 50% of the original set rate). If at the next temperature point T(i+1), the weight loss percentage WL returns to the standard WL ≥ WL min (i+1), then from the next temperature point T(i+1), continue to implement the original process system. If the weight loss percentage WL is still lower than the standard WL <WL min (i+1), the calcination process is immediately interrupted and cooling is carried out. After the kiln and materials have cooled to room temperature, the materials and equipment are checked.

[0131] In addition, in order to help the weight loss percentage return to the standard as soon as possible, while adopting method one or method two, you can also increase the intake and exhaust air volumes. For example, double the intake air volume of the process gas, keep the furnace pressure unchanged, and double the exhaust air volume.

[0132] 3. When the weight loss percentage WL(i) of a batch of calcination process at a certain temperature point T(i) is higher than the mass production standard WL ≥ WL max (i) indicates that the calcination process is abnormal, which may be due to abnormal raw material ratio or abnormal temperature indication of the thermocouple 900 in the furnace. The calcination process should be interrupted immediately and cooled. After the kiln and materials have cooled to room temperature, check the materials and equipment.

[0133] Corresponding to the above control method, such a control system can be realized by combining a kiln and other electronic components, as described below.

[0134] The control system includes the following commercially available equipment: thermocouples, weight sensors, weight meters, programmable logic controllers (PLCs), power controllers, electric heaters, as well as air supply valves, furnace pressure sensors, exhaust fans, and exhaust fan controllers.

[0135] 1. Program the PLC and input the aforementioned control logic into the PLC;

[0136] 2. Set the weight change percentage range WL at different furnace chamber temperatures T(i) on the PLC through the human-machine interface (e.g. touch screen) min (i) and WL max (i);

[0137] 3. The thermocouple installed in the furnace chamber collects the temperature in the furnace chamber in real time and sends the temperature signal T to the PLC;

[0138] 4. The weight sensor transmits the weight W to the PLC in real time through the weight meter.

[0139] 5. The PLC records the initial weight W(0) at the beginning of the temperature rise and uses it as the denominator for the calculation of the percentage weight change.

[0140] 6. When the temperature reaches the specified temperature point T(i), the PLC calculates the weight change percentage WL(i) at this time based on the weight W(i) and W(0) at this time:

[0141]

[0142] Then the PLC compares WL(i) with the set WL min (i) and WL max (i)Comparison:

[0143] If WL(i) is within the set range, the PLC continues to execute the originally set temperature program.

[0144] If WL(i) is greater than WL max (i), the PLC issues a command to stop heating and issues an alarm message.

[0145] If WL(i) is lower than WL min (i), the PLC starts the following set actions (corresponding to method 1 or method 2 in the above control logic).

[0146] a) When executing method 1, the PLC adjusts the heating power of the electric heater through the power controller to maintain the furnace temperature at T(i), and starts timing to record the constant temperature time t. At the same time, the PLC calculates the real-time weight loss percentage WL based on the real-time weight W:

[0147]

[0148] When WL is equal to or higher than WL min After (i), PLC continues the originally set heating program from the temperature point T(i). max When WL is still lower than WL min (i) The PLC issues a command to stop heating and sends out an alarm message to remind the technicians to handle it.

[0149] b) When executing method 2, the PLC adjusts the heating power of the electric heater through the power controller to reduce the heating rate (for example, to half of the preset heating rate). Then, when the furnace chamber temperature reaches the next temperature point T(i+1), the PLC calculates the weight loss percentage WL(i+1) at this time:

[0150]

[0151] If WL min (i+1)≤WL(i+1)≤WL max (i), PLC starts from temperature T(i+1) and continues the originally set heating program. Otherwise, PLC issues a command to stop heating and issues an alarm message.

[0152] If you want to adjust the intake and exhaust volume, in conjunction with the above adjustments, to accelerate the weight loss percentage back to the standard range, connect the PLC to the intake valve. The PLC controls the intake volume by controlling the opening of the intake valve.

[0153] At the same time, the furnace pressure is set to a fixed value, and the furnace pressure sensor installed in the furnace cavity is connected to the exhaust fan controller. The exhaust fan controller can adjust the speed of the exhaust fan, thereby adjusting the exhaust volume. <WL min (i) The PLC is triggered to change the originally set temperature program. While adjusting the power controller, the PLC sends a signal to the air intake valve to increase the opening of the air intake valve (for example, to double the original setting value) to increase the air intake volume. At the same time, since the furnace pressure is set to a fixed value, the exhaust fan controller will increase the speed of the exhaust fan and increase the exhaust volume.

[0154] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A calcination method for processing an object that can change its weight when heated, characterized in that: The calcination method comprises: Obtaining preset conditions corresponding to the calcination process of the processing object; the preset conditions include a first reference condition of a correspondence between a preset cumulative mass loss amount of the calcination object and a preset calcination temperature during a process from the start of calcination to the completion of calcination; the preset conditions also include initial calcination parameters corresponding to the processing object; Setting initial calcination parameters to calcine the processing object, and during the calcination process, continuously collecting the actual mass cumulative loss and the actual calcination temperature of the calcination object, and obtaining a corresponding relationship between the actual mass cumulative loss and the actual calcination temperature as a first working condition; Controlling the initial calcination parameters according to a trigger condition, wherein the trigger condition is determined based on a comparison result of a preset mass cumulative loss amount and an actual mass cumulative loss amount corresponding to a selected same calcination temperature point; The trigger condition includes: the actual cumulative mass loss is equal to the preset cumulative mass loss; Alternatively, the actual cumulative mass loss amount is not equal to the preset cumulative mass loss amount.

2. The calcination method according to claim 1, characterized in that The trigger condition includes: the actual cumulative mass loss is higher than the upper limit of the preset cumulative mass loss.

3. The calcination method according to claim 1, characterized in that The trigger condition includes: the actual cumulative mass loss is lower than the lower limit of the preset cumulative mass loss.

4. The calcination method according to claim 1, characterized in that The conditions for controlling the calcination according to the trigger conditions include: When the actual cumulative mass loss is equal to the preset cumulative mass loss, the calcination is continued while keeping the initial calcination parameters unchanged; Alternatively, at the selected calcination temperature point, when the absolute value of the difference between the actual cumulative mass loss under the first working condition and the preset cumulative mass loss under the first reference condition is within a preset range, the calcination is continued while keeping the initial calcination parameters unchanged.

5. The calcination method according to claim 1, characterized in that: The conditions for controlling the calcination according to the trigger conditions include: At the selected calcination temperature point, when the actual cumulative mass loss is higher than the upper limit of the preset cumulative mass loss, stopping the calcination; Alternatively, at a selected calcination temperature point, when the actual cumulative mass loss is lower than the lower limit of the preset cumulative mass loss, the selected calcination temperature point is maintained for a selected time, and when the actual cumulative mass loss is still lower than the lower limit of the preset cumulative mass loss after exceeding the selected time or exceeding a maximum set time greater than the selected time, the calcination is stopped; Alternatively, at a selected calcination temperature point, when the actual cumulative mass loss is lower than the lower limit of the preset cumulative mass loss, the calcination heating rate is reduced until the next selected calcination temperature point, and when the next selected calcination temperature point is reached, if the actual cumulative mass loss is still less than the lower limit of the actual cumulative mass loss corresponding to the next selected calcination temperature point, the calcination is stopped.

6. The calcination method according to claim 1, characterized in that The conditions for controlling the calcination according to the trigger conditions include: At a selected calcination temperature point, when the actual mass cumulative loss is lower than the lower limit of the preset mass cumulative loss, the selected calcination temperature point is maintained for a selected time until the actual mass cumulative loss is greater than the lower limit of the preset mass cumulative loss, the temperature is raised, and calcination is performed according to the parameters of the initial calcination parameters set after the selected calcination temperature point; Alternatively, at a selected calcination temperature point, when the actual cumulative mass loss is lower than the lower limit of the preset cumulative mass loss, the calcination heating rate is reduced until the next selected calcination temperature point, and when the next selected calcination temperature point is reached, when the actual cumulative mass loss is greater than the lower limit of the actual cumulative mass loss corresponding to the next selected calcination temperature point, the initial calcination parameters are continued to be maintained from the next selected calcination temperature point.

7. The calcination method according to claim 1, characterized in that The weight of the processing object changes and gas is generated when heated, and the preset condition further includes a second reference condition of a correspondence between a preset concentration of the gas and a preset calcination temperature; The calcination method further comprises: during the calcination process, continuously collecting the correspondence between the actual concentration of the gas in the calcination environment and the actual calcination temperature as a second working condition; The trigger condition is determined based on the comparison result of the actual mass cumulative loss corresponding to the same selected calcination temperature point and the preset mass cumulative loss amount, and the comparison result of the actual concentration of the gas corresponding to the same selected calcination temperature point and the preset concentration.

8. An intermittent kiln for implementing the calcination method according to any one of claims 1 to 7 to produce inorganic non-metallic materials and products thereof, characterized in that: The intermittent kiln comprises: The furnace body comprises a furnace cavity which is enclosed by a furnace wall, a furnace top and a furnace bottom to provide a calcining space, wherein the furnace wall is provided with a furnace door for opening and closing the furnace cavity, the furnace wall and the furnace top are cooperatively connected, and the furnace bottom is opposite to the furnace top and cooperatively connected to the furnace wall; A heater installed in the furnace body, used to provide heat to the furnace cavity for calcination; A temperature sensor installed in the furnace body, used to detect the calcination temperature condition in the furnace chamber; The weighing meter is used to continuously detect the weight of the calcining object placed in the furnace chamber.

9. The intermittent kiln according to claim 8, characterized in that: The intermittent kiln comprises a gas monitor for detecting the concentration of a selected gas in the furnace chamber; and / or the furnace bottom cooperates with the furnace wall via a curved sealing groove.

10. The intermittent kiln according to claim 9, characterized in that: The furnace body is provided with an air inlet pipe and an exhaust pipe, and the gas monitor is arranged on the exhaust pipe; And / or, the furnace bottom includes a support frame and a refractory layer for placing the calcined object, and the refractory layer is located on the support frame.

11. The intermittent kiln according to claim 8, characterized in that: The intermittent kiln includes a column, the weighing meter is in contact with the furnace bottom through the column, the furnace bottom is in gap with the furnace wall, and the furnace bottom can freely move a given distance from the furnace top to the furnace bottom, the weighing meter is in contact with the furnace bottom through the column outside the furnace cavity, and the weighing meter detects the weight of the calcined object placed on the furnace bottom through the free movement of the furnace bottom; Alternatively, the intermittent kiln includes a horizontal column for placing the calcined object, the horizontal column passes through the furnace wall and can move freely a given distance from the furnace top to the furnace bottom, the furnace bottom is tightly matched with the furnace wall, and the weighing meter cooperates with the horizontal column outside the furnace cavity and detects the weight of the calcined object placed on the furnace bottom through the free movement of the horizontal column.

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