Metal silicon recovery rate detection method

Abstract

According to the method for detecting the recovery rate of the metal silicon, after the metal silicon is cast into an ingot, an identification plate with the density of 2.7-2.8 g / cm < 3 > is put into a central area of molten aluminum at the bottom of a furnace in a state that a vertical identification block faces upwards. Due to the fact that the density of the identification plate is slightly higher than the density of molten aluminum of the aluminum-silicon alloy with the silicon content of 11% in the molten state, the identification plate can naturally sink to the position close to the position below a silicon-containing molten aluminum layer with the high purity degree, an operator collects the silicon-containing aluminum material located above the identification plate, and then the silicon-containing aluminum material with the high purity degree can be collected. Due to the fact that the identification plate is provided with the vertical identification block, an operator can confirm that the current liquid level belongs to a silicon-containing aluminum liquid layer with high purity through the identification block. Once the operator judges that the bottom limit of the high-purity molten aluminum layer is approached or reached at the moment through the identification block, and the purity of the residual molten aluminum is obviously reduced, the collection is stopped. Compared with the mode of subjective judgment only by experience and naked eyes in the prior art, the method can effectively reduce errors in the recovery rate detection process.

Description

Technical Field

[0001] The present invention relates to the technical field of the detection of the recovery rate of metallurgical silicon, and particularly relates to a method for detecting the recovery rate of metallurgical silicon. Background Art

[0002] Aluminum product manufacturers usually purchase pure aluminum ingots and silicon alloys from the outside and put them into a melting furnace for smelting to prepare an aluminum-silicon alloy with a silicon content of 11%. The melting furnace is generally provided with structures such as an operation port, a liquid outlet, a slag cleaning port, and a temperature measuring hole. Among them, the bottom edge of the liquid outlet is higher than the furnace bottom, and the slag cleaning port is located at the lower part of the melting furnace. In the normal state, the liquid outlet, the slag cleaning port, and the temperature measuring hole are all in a closed state and are only opened when needed. Operators can operate the molten aluminum liquid in the furnace through the operation port, for example, using a slag scraping rake to remove the alumina floating slag on the surface. During the smelting process, the infusible impurities (such as quartz, silicate, etc.) in the silicon alloy will mostly settle to the furnace bottom due to their large density. After the smelting is completed, the operator opens the valve of the liquid outlet, discharges the silicon-containing aluminum liquid with a low impurity content and casts it into aluminum-silicon alloy ingots. During this process, since the position of the liquid outlet is higher than the furnace bottom, the aluminum liquid at the furnace bottom will not be discharged from the liquid outlet but will remain at the furnace bottom. Subsequently, the operator puts in a new batch of pure aluminum ingots and silicon alloys and starts a new round of smelting. When the residues accumulated at the furnace bottom are too many and affect the production efficiency, the operator can open the closing door of the slag cleaning port and use a long-handled tool to reach into the furnace bottom to clean the residual materials.

[0003] The content of infusible impurities in the silicon alloys provided by different manufacturers varies. If the content of infusible impurities is low, the residual impurities at the furnace bottom are less and the cleaning frequency is lower; on the contrary, if the content of infusible impurities is high, the cleaning frequency increases. The industry usually uses the "recovery rate" as a standard to measure the purity of materials. The so-called recovery rate refers to the ratio of the output weight to the input weight, and the calculation formula is: the weight of the produced aluminum-silicon alloy divided by the total weight of the input aluminum and silicon. For example, during the smelting process, 100 kg of aluminum ingots and 13 kg of metallurgical silicon are put into the melting furnace. After the smelting is completed, 104 kg of aluminum-silicon alloy is discharged from the liquid outlet and cast. However, since there may be a part of the silicon-containing aluminum liquid with a high purity remaining at the furnace bottom, this part of the aluminum liquid should be included in the total output. Therefore, when actually calculating the recovery rate, the weight of the silicon-containing aluminum liquid with a high purity at the furnace bottom should be added to 104 kg as the weight of the produced aluminum-silicon alloy, and then divided by the weight of the input aluminum and silicon (i.e., 113 kg). Since the aluminum liquid with a high purity at the furnace bottom is generally located in the upper layer, the traditional method is to rely on manual scooping to collect this part of the aluminum liquid. During this process, the operator can only subjectively judge the purity of the scooped aluminum liquid based on experience and the naked eye, which is likely to cause a large error in the calculation result of the recovery rate due to misjudgment. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for detecting the recovery rate of metallurgical silicon, and the calculation result of the recovery rate of this detection method has a small error.

[0005] The inventors' research found that in the molten state, the density of the aluminum liquid in the aluminum-silicon alloy with a silicon content of 11% is usually between 2.6 and 2.7 g / cm 3 Therefore, if a plate with a density slightly higher than this value is put into the bottom of the furnace, for example, a plate with a density of 2.7 - 2.8 g / cm 3 of the plate, the plate will naturally sink to near the bottom of the silicon-containing aluminum liquid layer with higher purity. If an upward identification block is set on the plate, the plate can be used as an "identification plate". When the operator collects the high-purity aluminum liquid remaining at the bottom of the furnace, it can be observed whether the identification block of the identification plate has emerged from the liquid surface. Once it is visually observed that the identification block has emerged from the liquid surface, it can be judged that the bottom limit of the high-purity aluminum liquid has been approached or reached, and the purity of the remaining aluminum liquid has decreased significantly, and the collection should be stopped. Compared with the existing method of subjective judgment based on experience and the naked eye, this method has higher accuracy and can effectively reduce the error in the calculation of the recovery rate.

[0006] To solve the above technical problems, a method for detecting the recovery rate of metallurgical silicon according to the present invention includes the following steps executed in sequence:

[0007] Smelting of aluminum ingots: Put the aluminum ingots into the furnace for smelting;

[0008] Adding the metallurgical silicon to be measured: Randomly extract the metallurgical silicon from the pile of metallurgical silicon to be measured and put it into the furnace for smelting;

[0009] Casting into ingots: Drain the silicon-containing aluminum liquid in the furnace from the liquid outlet, cast the drained silicon-containing aluminum liquid into aluminum-silicon alloy ingots, and weigh them after cooling;

[0010] Putting in the identification plate: Put the identification plate with a vertical identification block and a density of 2.7 - 2.8 g / cm 3 The identification plate is put into the central area of the aluminum liquid at the bottom of the furnace with the vertical identification block facing up, and the silicon-containing aluminum liquid overflowing from the liquid outlet during this process is collected and weighed after cooling;

[0011] Collecting the silicon-containing aluminum material above the identification plate: Observe the liquid surface, confirm that the identification block of the identification plate has not emerged above the liquid surface, collect the silicon-containing aluminum material located above the identification plate until the identification block of the identification plate emerges from the liquid surface, and weigh the collected silicon-containing aluminum material.

[0012] Calculating the recovery rate of metallurgical silicon: Add the weights of the cast aluminum-silicon alloy ingots, the silicon-containing aluminum liquid overflowing from the liquid outlet, and the collected silicon-containing aluminum material to calculate the weight of the produced aluminum-silicon alloy, add the weights of the put-in aluminum ingots and metallurgical silicon to calculate the weight of the put-in aluminum-silicon, and divide the weight of the produced aluminum-silicon alloy by the weight of the put-in aluminum-silicon to calculate the recovery rate of metallurgical silicon.

[0013] Furthermore, the put-in identification plate is specifically a heat-insulating identification plate;

[0014] Including a step of lowering the temperature of the molten aluminum at the furnace bottom, which is carried out after the step of putting in the identification plate and before the step of collecting the aluminum material above the identification plate: reducing the heating power of the melting furnace to lower the temperature of the molten aluminum at the furnace bottom;

[0015] In the step of collecting the aluminum material above the identification plate, specifically, collecting the aluminum block layer formed by solidification in the area above the heat insulation identification plate on the liquid surface of the molten aluminum at the furnace bottom.

[0016] Furthermore, the input heat insulation identification plate is specifically a heat insulation identification plate with vertical identification blocks at the edge.

[0017] Furthermore, in the step of putting in the identification plate, specifically putting the heat insulation identification plate into the central area of the molten aluminum at the furnace bottom;

[0018] In the step of lowering the temperature of the molten aluminum at the furnace bottom, using a thermocouple to extend into the melting furnace to detect the temperature of the molten aluminum in the edge area of the furnace bottom, and reducing the heating power of the melting furnace to lower the temperature of the molten aluminum at the furnace bottom is specifically to reduce the temperature of the molten aluminum to 660 - 665 °C.

[0019] Furthermore, the input heat insulation identification plate is specifically a ceramic heat insulation identification plate.

[0020] Furthermore, preparing the ceramic heat insulation identification plate before performing the aluminum ingot melting step includes the following steps:

[0021] Mixing raw materials: uniformly mixing 68 - 72% of alumina powder, 26 - 30% of polystyrene microspheres, and 2% of PVA binder together;

[0022] Dry pressing and forming: using a steel mold and a graphite bottom plate, pressing into multiple circular green bodies with a diameter of 600 - 900 mm and a thickness of 8 - 10 mm under a pressure of 200 MPa, and integrally forming an identification block with a height of 10 - 15 mm and a diameter of 50 mm at the top edge of the green body;

[0023] Degreasing: placing the green body in a high-temperature environment of 400 - 600 °C and keeping it warm for 1 - 2 hours to remove the polystyrene microspheres;

[0024] Sintering: placing the degreased green body in a high-temperature environment of 1400 - 1500 °C and keeping it warm for 1 - 2 hours to sinter the alumina particles densely, retaining the pores formed in situ by the microspheres, and finally forming a ceramic heat insulation identification plate with a porosity of 30 - 35%;

[0025] Measuring density: using the Archimedes method to detect the density of the ceramic heat insulation identification plate, and selecting a ceramic heat insulation identification plate with a density of 2.7 - 2.8 g / cm 3 for subsequent use.

[0026] Since the identification plate has a density of 2.7 - 2.8 g / cm 3, slightly higher than the density of the aluminum-silicon alloy with a silicon content of 11% in the molten state. After the plate is put into the furnace bottom, it will naturally sink to near the lower part of the silicon-containing aluminum liquid layer with higher purity. Then, when the operator collects the silicon-containing aluminum material above the identification plate, the silicon-containing aluminum material with higher purity can be collected. Since the identification plate is provided with vertical identification blocks, once the operator confirms that the identification blocks do not float above the liquid surface, it can be confirmed that the current liquid surface belongs to the silicon-containing aluminum liquid layer with higher purity and collection can be carried out. Once the operator observes with the naked eye that the identification blocks have floated out of the liquid surface, it can be judged that the bottom limit of the high-purity aluminum liquid layer has been approached or reached at this time, and the purity of the remaining aluminum liquid has decreased significantly, and the collection is stopped. Compared with the existing method of subjective judgment only by experience and the naked eye, this method can effectively reduce the error in the calculation of the recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of the detection method.

[0028] Figure 2 is a schematic diagram of the identification plate preparation stage.

[0029] Figure 3 is a schematic diagram of the test stage.

[0030] Figure 4 is a schematic diagram of the operation port, liquid outlet, and slag cleaning port of the furnace used in this method.

[0031] Figure 5 is a schematic diagram of the temperature measurement hole of the furnace used in this method.

[0032] Figure 6 is a schematic diagram of the identification plate used in this method. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The following further describes the present invention in detail in conjunction with the specific embodiments.

[0034] A method for detecting the recovery rate of metallic silicon. The furnace used in this method is shown in Figure 4 and Figure 5 , and its parameters are as follows: the inner diameter is 1.5 m, the bottom edge of the liquid outlet 13 is 100 mm higher than the furnace bottom, a normally closed valve is provided at the liquid outlet 13, the operation port 11 is 1 m long and 0.5 m high; the furnace body is provided with a plurality of temperature measurement holes 14 arranged vertically in parallel, and the lowermost temperature measurement hole 14 is aligned with the furnace bottom edge area. The temperature measurement holes 14 are usually closed and only opened during temperature measurement; a slag cleaning port 12 with a diameter of 500 mm is opened in the middle and lower part of the furnace body, and a closing door is provided at the slag cleaning port 12.

[0035] This method is shown in Figure 1 , and includes a prior identification plate preparation stage and a subsequent test stage.

[0036] The preparation stage of the identification plate is shown in Figure 2 , and includes the following steps executed in sequence:

[0037] Mix raw materials: Uniformly mix 70% alumina powder, 28% polystyrene microspheres, and 2% PVA binder together.

[0038] Dry pressing forming: Using a steel mold and a graphite bottom plate, press into 3 - 5 circular green compacts with a diameter of 600 - 900 mm and a thickness of 8 - 10 mm under a pressure of 200 MPa. A vertical identification block 21 with a height of 10 - 15 mm and a diameter of 50 mm is integrally formed at the top edge of the green compact, as Figure 6 shown.

[0039] Debinding: Place the green compact in a high - temperature environment of 400 - 600 °C and keep it warm for 1 - 2 hours to remove the polystyrene microspheres.

[0040] Sintering: Place the debound green body in a high - temperature environment of 1400 - 1500 °C and keep it warm for 1 - 2 hours to sinter the alumina particles densely, retaining the pores formed in situ by the microspheres, and finally form Figure 6 a ceramic heat - insulating identification plate 2 with a porosity of 30 - 35%.

[0041] Density measurement: Use the Archimedes method to detect the density of the identification plate 2, and select the identification plate 2 with a density of 2.7 - 2.8 g / cm 3 for use in the testing stage.

[0042] The testing stage is shown in Figure 3 , and includes the following steps executed in sequence:

[0043] Aluminum ingot melting: Take out a 100 - kg aluminum ingot with an aluminum content of 99.7% and put it into the furnace for melting.

[0044] Skim the dross: Use a dross - scraping rake to scrape the alumina dross on the surface of the molten aluminum from the operation port 11, and weigh the scraped dross.

[0045] First sampling: According to the height of the molten aluminum liquid level, use a thermocouple to extend into the furnace interior from the corresponding temperature - measuring hole 14 to detect the temperature of the molten aluminum liquid level. When the temperature reaches 700 - 730 °C, take a sample from the operation port 11 using a sampling tool. After sampling, weigh the sample, and then use a spectrometer to analyze the content of each element in the sample.

[0046] Add the silicon metal to be tested: Randomly select 13 kg of silicon metal from the silicon metal pile to be tested and put it into the furnace for melting for 60 - 90 minutes. During the melting process, adjust the heating power of the furnace according to the detection results of the thermocouple to keep the temperature of the molten aluminum liquid between 780 - 800 °C, and stir it once every 20 minutes during the furnace process.

[0047] Second sampling: Sampling is carried out from the operation port 11 using a sampling tool. After sampling, the sample is weighed, and then the content of each element in the sample is analyzed using a spectrometer.

[0048] Casting into ingots: After standing for 10 minutes, the heating power of the furnace is lowered to reduce the temperature of the molten aluminum liquid in the furnace. The cooling rate is controlled at 20 - 30 °C / min, so that the temperature of the aluminum liquid in the furnace slowly drops from 780 - 800 °C to 700 - 720 °C. Then, the valve at the liquid outlet 13 is opened, and the silicon-containing aluminum liquid in the furnace is discharged from the liquid outlet 13 and cast into an aluminum-silicon alloy ingot. After it cools down, it is weighed.

[0049] Inserting the identification plate: The identification plate 2 is inserted from the operation port 11 into the central area of the aluminum liquid at the bottom of the furnace with the vertical identification block 21 facing upward. The silicon-containing aluminum liquid overflowing from the liquid outlet 13 during this process is collected and weighed after it cools down. Since the density of the identification plate 2 is 2.7 - 2.8 g / cm 3 , slightly higher than the density of the aluminum liquid in the molten state of the aluminum-silicon alloy with a silicon content of 11%, after the plate is inserted into the bottom of the furnace, it will naturally sink to near the lower part of the silicon-containing aluminum liquid layer with higher purity. The content of metallic silicon impurities generally does not exceed 5%, so at this time, the liquid level of the aluminum liquid at the bottom of the furnace is generally a silicon-containing aluminum liquid layer with higher purity. The ceramic heat-insulating identification plate 2 naturally sinks to near the lower part of the silicon-containing aluminum liquid layer with higher purity, that is, it sinks to below the central area of the liquid level of the aluminum liquid at the bottom of the furnace.

[0050] Cooling the aluminum liquid at the bottom of the furnace: A thermocouple is inserted into the furnace from the lowest temperature measuring hole 14 to detect the temperature of the molten aluminum liquid in the bottom edge area of the furnace. The heating power of the furnace is continuously lowered to reduce the temperature of the molten aluminum liquid in the bottom edge area. The cooling rate is controlled at 20 - 30 °C / min until the temperature of the aluminum liquid slowly drops from 700 - 720 °C to 660 - 665 °C. Since the ceramic heat-insulating identification plate 2 blocks the vertical heat conduction in the central area of the aluminum liquid at the bottom of the furnace, the central area of the liquid level of the aluminum liquid at the bottom of the furnace can only obtain heat from the edge area through lateral heat conduction. Therefore, the temperature of the central area of the liquid level of the aluminum liquid at the bottom of the furnace is lower than that of the edge area, and silicon-containing aluminum blocks will continuously solidify to form a layer of silicon-containing aluminum blocks in the central area of the liquid level of the aluminum liquid at the bottom of the furnace. The layer of silicon-containing aluminum blocks is located above the identification plate 2 and belongs to silicon-containing aluminum materials with higher purity.

[0051] Collect the silicon-aluminum blocks above the identification plate: After a silicon-aluminum block layer is formed by solidification in the central area of the molten aluminum surface at the bottom of the furnace, first observe the liquid surface from the operation port 11 to confirm that the identification block 21 of the identification plate 2 does not float above the liquid surface. Open the closing door of the slag cleaning port 12, and use a long-handled iron hook / long-handled shovel to collect the silicon-aluminum block layer in the central area of the molten aluminum surface at the bottom of the furnace from the slag cleaning port 12. After collecting one layer, wait for the molten aluminum in this area to solidify again to form a new silicon-aluminum block layer, and then perform the next collection operation. After performing the collection operation 3 to 5 times, observe the liquid surface from the operation port 11 again; if the identification block 21 still does not float above the liquid surface, it can be confirmed that the current liquid surface belongs to a silicon-aluminum liquid layer with a relatively high purity and can be collected. Then the operator continues to perform the collection operation 3 to 5 times, and then observes the liquid surface from the operation port 11 again, and so on until the identification block 21 floats out of the liquid surface. When the operator observes that the identification block floats out of the liquid surface, it can be judged that the bottom limit of the high-purity aluminum liquid layer is approaching or has been reached, and the purity of the remaining molten aluminum has decreased significantly, then stop collecting, and then weigh the collected silicon-aluminum blocks. Compared with the existing method of relying solely on experience and subjective visual judgment, this method can effectively reduce the error in the calculation of the recovery rate.

[0052] Calculate the recovery rate of metallic silicon: Add the weights of the cast aluminum-silicon alloy ingot, the silicon-aluminum liquid overflowing from the liquid outlet 13, the collected silicon-aluminum materials, and the weight of the second sampling sample to calculate the weight of the produced aluminum-silicon alloy. Add the weights of the input aluminum ingot and metallic silicon, subtract the scraped floating slag and the weight of the first sampling sample to calculate the input aluminum-silicon weight, and divide the weight of the produced aluminum-silicon alloy by the input aluminum-silicon weight to calculate the recovery rate of metallic silicon. The following is an example:

[0053] The weight of the scraped floating slag is 0.15 kg, the weight of the first sampling sample is 0.25 kg, the weight of the second sampling sample is 0.25 kg, the weight of the cast aluminum-silicon alloy ingot is 104 kg, the weight of the silicon-aluminum block formed by cooling the silicon-aluminum liquid overflowing from the liquid outlet when the identification plate is put in is 0.5 kg, and the total weight of the removed solidified silicon-aluminum blocks is 5 kg. Then the recovery rate of metallic silicon is:

[0054] (104 + 0.5 + 5 + 0.25) / (100 + 13 - 0.15 - 0.25) = 109.75 / 112.6 ≈ 97.47%

[0055] After calculating the recovery rate of metallic silicon, the iron content and calcium content of metallic silicon can be calculated according to the results of the two samplings and analyzed whether they meet the standards. The following is an example:

[0056] For 551 metallic silicon, its national standard is that the iron content is less than 0.5%. When analyzing the first sampling, the sample weight is 0.5 kg and the iron content is 0.00002%. When analyzing the second sampling, the iron content of the sample is 0.0005%. Then the iron content of metallic silicon is:

[0057] [(100 - 0.5 + 13) × 0.0005] - [(100 - 0.5) × 0.00002] = 0.05426

[0058] 0.05426 / 13 ≈ 0.417%, meeting the national standard.

[0059] The calculation method of calcium content in metallurgical silicon is the same as that of iron content, so it will not be elaborated here.

[0060] In this embodiment, the raw materials for preparing the ceramic heat-insulating identification board 2 are 70% alumina powder, 28% polystyrene microspheres, and 2% PVA binder. In other embodiments, the content of alumina powder can be any value between 68% and 72%, and the content of polystyrene microspheres can be any value between 26% and 30%.

[0061] In other embodiments, the three steps of skimming dross, the first sampling, and the second sampling are cancelled. When calculating the recovery rate of metallurgical silicon, add the weights of the cast aluminum-silicon alloy ingot, the silicon-containing aluminum liquid overflowing from the liquid outlet 13, and the collected silicon-containing aluminum material to calculate the weight of the produced aluminum-silicon alloy. Add the weights of the input aluminum ingot and metallurgical silicon to calculate the input aluminum-silicon weight. Divide the weight of the produced aluminum-silicon alloy by the input aluminum-silicon weight to calculate the recovery rate of metallurgical silicon.

[0062] In other embodiments: In the step of putting in the identification board, put the identification board 2 into any area of the molten aluminum at the bottom of the furnace with the vertical identification block 21 facing up from the operation port 11; after performing the step of cooling the molten aluminum at the bottom of the furnace, when the temperature of the molten aluminum drops to 660 - 665 °C, the area above the identification board on the surface of the molten aluminum at the bottom of the furnace will solidify to form a silicon-containing aluminum block layer; in the step of collecting the silicon-containing aluminum blocks above the identification board, it is correspondingly changed to collect the silicon-containing aluminum block layer solidified in the area above the identification board on the surface of the molten aluminum at the bottom of the furnace.

[0063] As described above, this is only the implementation mode of the present invention, and does not limit the scope of patent protection. Those skilled in the art make non-substantive changes or substitutions based on the present invention, and still fall within the scope of patent protection.

Claims

1. A method for detecting the recovery rate of metallurgical silicon, comprising the following steps executed in sequence: Melting of aluminum ingots: Put aluminum ingots into a furnace for melting. Adding metallurgical silicon to be measured: Randomly extract metallurgical silicon from the pile of metallurgical silicon to be measured and put it into the furnace for melting. Casting into ingots: Drain the silicon-containing aluminum liquid in the furnace from the liquid outlet, cast the drained silicon-containing aluminum liquid into aluminum-silicon alloy ingots, and weigh them after cooling. Input identification plate: Put in a density of 2.7 - 2.8 g / cm with vertical identification blocks 3 Put the identification plate into the central area of the molten aluminum at the bottom of the furnace with the vertical identification blocks facing up, collect the silicon-containing molten aluminum overflowing from the liquid outlet during this process, and weigh it after it cools down; Collecting the silicon-containing aluminum material above the identification plate: Observe the liquid level, confirm that the identification block of the identification plate does not float above the liquid level, collect the silicon-containing aluminum material located above the identification plate until the identification block of the identification plate floats out of the liquid level, and weigh the collected silicon-containing aluminum material. Calculating the recovery rate of metallurgical silicon: Add the weights of the cast aluminum-silicon alloy ingots, the silicon-containing aluminum liquid overflowing from the liquid outlet, and the collected silicon-containing aluminum material to calculate the weight of the produced aluminum-silicon alloy. Add the weights of the input aluminum ingots and metallurgical silicon to calculate the input aluminum-silicon weight. Divide the weight of the produced aluminum-silicon alloy by the input aluminum-silicon weight to calculate the recovery rate of metallurgical silicon.

2. The detection method according to claim 1, wherein: The input identification plate is specifically a heat-insulating identification plate. It includes a step of lowering the temperature of the molten aluminum at the furnace bottom, which is executed after the step of putting in the identification plate and before the step of collecting the aluminum material above the identification plate: Lower the heating power of the furnace to reduce the temperature of the molten aluminum at the furnace bottom. In the step of collecting the aluminum material above the identification plate, specifically, it is to collect the aluminum block layer formed by solidification in the area above the heat-insulating identification plate on the liquid surface of the molten aluminum at the furnace bottom.

3. The detection method according to claim 2, characterized in that: The input heat-insulating identification plate is specifically a heat-insulating identification plate with vertical identification blocks on the edge.

4. The detection method according to claim 3, wherein: In the step of putting in the identification plate, specifically put the heat-insulating identification plate into the central area of the molten aluminum at the furnace bottom. In the step of lowering the temperature of the molten aluminum at the furnace bottom, use a thermocouple to extend into the furnace to detect the temperature of the molten aluminum in the edge area of the furnace bottom. Lowering the heating power of the furnace to reduce the temperature of the molten aluminum at the furnace bottom is specifically to reduce the aluminum liquid temperature to 660 - 665 °C.

5. The detection method according to claim 2, wherein: The input heat-insulating identification plate is specifically a ceramic heat-insulating identification plate.

6. The detection method according to claim 5, wherein: Prepare the ceramic heat-insulating identification plate before performing the step of melting aluminum ingots, including the following steps: Mixing raw materials: Uniformly mix 68 - 72% of alumina powder, 26 - 30% of polystyrene microspheres, and 2% of PVA binder together. Dry pressing and forming: Use a steel mold and a graphite bottom plate to press into multiple circular green blanks with a diameter of 600 - 900 mm and a thickness of 8 - 10 mm under a pressure of 200 MPa. A 10 - 15 mm high and 50 mm diameter identification block is integrally formed at the top edge of the green blank. Debinding: Place the green blank in a high-temperature environment of 400 - 600 °C and keep it warm for 1 - 2 hours to remove the polystyrene microspheres. Sintering: Place the debound green body in a high-temperature environment of 1400 - 1500 °C and keep it warm for 1 - 2 hours to sinter the alumina particles densely, retain the pores formed in situ by the microspheres, and finally form a ceramic heat-insulating identification plate with a porosity of 30 - 35%. Measuring density: Use the Archimedes method to detect the density of the ceramic heat insulation identification board, and select the ceramic heat insulation identification board with a density of 2.7 - 2.8 g / cm 3 for subsequent use.

Images