Method for detecting metal silicon recovery rate

Abstract

The metal silicon recovery rate detection method of the present application, after casting into ingot, puts the density of 2.7~2.8g / cm 3 The identification plate is put into the center area of the aluminum liquid at the bottom of the furnace with the vertical identification block upward. Since the density of the identification plate is slightly higher than the density of the aluminum liquid in the molten state of the aluminum-silicon alloy with 11% silicon content, it will naturally sink to the vicinity below the high-purity silicon-containing aluminum liquid layer, and then the operator can collect the high-purity silicon-containing aluminum material above the identification plate. Since the identification plate is provided with vertical identification blocks, the operator can confirm through the identification blocks that the current liquid level belongs to the high-purity silicon-containing aluminum liquid layer. Once the operator judges through the identification blocks 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, the collection is stopped. Compared with the existing technology which is only based on experience and subjective judgment by the naked eye, the method can effectively reduce the error in the recovery rate detection process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal silicon recovery rate detection, and particularly relates to a metal silicon recovery rate detection method. BACKGROUND

[0002] Aluminum product manufacturers usually purchase pure aluminum ingots and silicon alloy from outside and put them into a smelting furnace to prepare aluminum silicon alloy with a silicon content of 11%. The smelting furnace is generally provided with an operating port, a liquid outlet, a slag removal port and a temperature measuring hole and the like. Among them, the bottom edge of the liquid outlet is higher than the furnace bottom, and the slag removal port is located at the lower part of the smelting furnace. Under normal conditions, the liquid outlet, the slag removal port and the temperature measuring hole are in a closed state and are opened only when needed. The operator can operate the molten aluminum liquid in the furnace through the operating port, for example, using a slag rake to remove the surface aluminum oxide dregs. In the smelting process, the non-melting impurities (such as quartz, silicate, etc.) in the silicon alloy are mostly settled at the bottom of the furnace due to their large density. After the smelting is completed, the operator opens the valve of the liquid outlet to discharge the silicon-containing aluminum liquid with low impurity content and cast it into aluminum silicon alloy ingots. In this process, since the position of the liquid outlet is higher than the bottom of the furnace, the aluminum liquid at the bottom of the furnace will not be discharged from the liquid outlet but will remain at the bottom of the furnace. Then, the operator puts in a new batch of pure aluminum ingots and silicon alloy to start a new round of smelting. When the residual material accumulated at the bottom of the furnace is too much to affect the production efficiency, the operator can open the closed door of the slag removal port and use a long-handled tool to clean the residual material in the bottom of the furnace.

[0003] The content of non-melting impurities in the silicon alloy provided by different manufacturers is different. If the content of non-melting impurities is low, the residual impurities at the bottom of the furnace are less and the cleaning frequency is low; otherwise, the cleaning frequency increases. The industry usually uses "recovery rate" as a standard to measure the purity of the material. The so-called recovery rate is the ratio of the output weight to the input weight, and the calculation formula is: the weight of the output aluminum silicon alloy divided by the total weight of the input aluminum silicon. For example, 100 kg of aluminum ingots and 13 kg of metal silicon are put into the smelting furnace during the smelting process, and 104 kg of aluminum silicon alloy is obtained after smelting and casting from the liquid outlet, but a part of the silicon-containing aluminum liquid with high purity may remain at the bottom of the furnace, which should be included in the total output. Therefore, when calculating the actual recovery rate, the weight of the silicon-containing aluminum liquid with high purity at the bottom of the furnace should be added to 104 kg as the output weight of the aluminum silicon alloy, and divided by the input weight of the aluminum silicon (i.e. 113 kg). Since the aluminum liquid with high purity at the bottom of the furnace is generally located in the upper layer, the traditional method is to collect this part of the aluminum liquid by manual scooping. In this process, the operator can only judge the purity of the scooped aluminum liquid by experience and naked eye, which is easy to cause large error in the calculation result of the recovery rate due to misjudgment. SUMMARY

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

[0005] The inventor has found that the density of the molten aluminum-silicon alloy with 11% silicon content is generally between 2.6 and 2.7 g / cm 3 Therefore, if a plate with a density slightly higher than the value, for example, a plate with a density of 2.7-2.8 g / cm 3 , is put into the bottom of the furnace, the plate will naturally sink to the vicinity below the layer of aluminum liquid with high purity and high silicon content. If an identification block facing upward is arranged on the plate, the plate can be used as an identification plate. The operator can observe whether the identification block of the identification plate has floated out of the liquid surface when collecting the high-purity aluminum liquid remaining in the bottom of the furnace. Once the identification block is observed to have floated out of the liquid surface, it is 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 been significantly reduced, and the collection should be stopped. Compared with the existing technology which is only based on experience and subjective judgment by naked eyes, the present method has higher accuracy and can effectively reduce the error in the calculation of the recovery rate.

[0006] To solve the above technical problems, the present application provides a metal silicon recovery rate detection method, which comprises the following steps executed in sequence:

[0007] Aluminum ingot smelting: put aluminum ingots into a smelting furnace for smelting;

[0008] Adding the metal silicon to be detected: randomly take metal silicon from the metal silicon pile to be detected and put it into the smelting furnace for smelting;

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

[0010] Putting an identification plate: put a density of 2.7-2.8 g / cm 3 The identification plate is put into the center area of the aluminum liquid in the bottom of the furnace with the vertical identification block facing upward, collect the silicon-containing aluminum liquid overflowing from the liquid outlet during this process, and weigh the silicon-containing aluminum liquid 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 floated above the liquid surface, collect the silicon-containing aluminum material above the identification plate until the identification block of the identification plate floats out of the liquid surface, and weigh the collected silicon-containing aluminum material.

[0012] Calculating the metal silicon recovery rate: 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, calculate the weight of the output aluminum-silicon alloy, add the weights of the input aluminum ingots and the metal silicon, calculate the weight of the input aluminum-silicon, and divide the weight of the output aluminum-silicon alloy by the weight of the input aluminum-silicon to calculate the metal silicon recovery rate.

[0013] Further, the identification plate is a heat-insulating identification plate.

[0014] including a furnace bottom molten aluminum temperature reduction step performed after the identification plate feeding step and before the molten aluminum above the identification plate collecting step: reducing the furnace heating power to reduce the temperature of the molten aluminum at the furnace bottom;

[0015] In the molten aluminum above the identification plate collecting step, specifically, the aluminum block layer is formed by solidification of the area of the molten aluminum liquid surface above the heat insulation identification plate.

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

[0017] Further, in the identification plate feeding step, the heat insulation identification plate is specifically fed to the central area of the molten aluminum at the furnace bottom.

[0018] In the furnace bottom molten aluminum temperature reduction step, the thermocouple is used to detect the temperature of the molten aluminum at the edge of the furnace bottom, and the furnace heating power is reduced to reduce the temperature of the molten aluminum at the furnace bottom, specifically to reduce the temperature of the molten aluminum to 660-665℃.

[0019] Further, the identification plate fed specifically is a ceramic heat insulation identification plate.

[0020] Further, the ceramic heat insulation identification plate is prepared before the aluminum ingot smelting step is performed, including the following steps:

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

[0022] Dry pressing: using a steel mold and a graphite bottom plate, press multiple circular green compacts with a diameter of 600-900mm and a thickness of 8-10mm under a pressure of 200MPa, and the identification blocks with a height of 10-15mm and a diameter of 50mm are integrally formed at the top edge of the green compacts;

[0023] Degreasing: place the green compacts in a high-temperature environment of 400-600℃ for 1-2 hours to remove the polystyrene microspheres;

[0024] Sintering: place the degreased compacts in a high-temperature environment of 1400-1500℃ for 1-2 hours to sinter the alumina particles to be dense, and retain the pores formed by the microspheres in situ, and finally form a ceramic heat insulation identification plate with a porosity of 30-35%;

[0025] Density measurement: use the Archimedes method to measure the density of the ceramic heat insulation identification plate, and select the ceramic heat insulation identification plate with a density of 2.7-2.8g / cm 3 for subsequent use.

[0026] Since the identification plate has a density of 2.7-2.8g / cm 3, slightly higher than the aluminum liquid density of the aluminum-silicon alloy with 11% silicon content in the molten state, after the plate is put into the furnace bottom, it will naturally sink to the vicinity below the silicon-containing aluminum liquid layer with higher purity, so that the operator can collect the silicon-containing aluminum material with higher purity above the identification plate. Since the identification plate is provided with vertical identification blocks, the operator can confirm that the current liquid level belongs to the silicon-containing aluminum liquid layer with higher purity by confirming that the identification blocks have not floated above the liquid level, and can collect. Once the operator observes with the naked eye that the identification blocks have floated out of the liquid level, 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 way of subjective judgment by experience and naked eye in the prior art, the method can effectively reduce the error in the calculation of the recovery rate. BRIEF DESCRIPTION OF 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 operating port, liquid outlet and slag removal port of the furnace used in the method.

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

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

[0033] The present invention will be further described in detail in conjunction with the specific embodiments.

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

[0035] The method is shown in Figure 1 , which includes a previously executed identification plate preparation stage and a subsequently executed test stage.

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

[0037] Mixing raw materials: 70% of the alumina powder, 28% of the polystyrene microspheres, and 2% of the PVA binder are uniformly mixed together.

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

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

[0040] Sintering: the debound compact is placed in a high-temperature environment of 1400-1500°C for 1-2 hours to sinter the alumina particles to be dense, and the pores formed by the microspheres in situ are retained, and finally a ceramic thermal insulation identification plate 2 with a porosity of 30-35% is formed, as shown in Figure 6 .

[0041] Density measurement: the density of the identification plate 2 is detected using the Archimedes method, and the identification plate 2 with a density of 2.7-2.8 g / cm 3 is selected 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: 100 kg of aluminum ingots with an aluminum content of 99.7% are taken out and put into a melting furnace for melting.

[0044] Scraping floating slag: alumina floating slag on the surface of the molten aluminum liquid is scraped off from the operating port 11 using a slag rake, and the scraped floating slag is weighed.

[0045] First sampling: according to the liquid level of the molten aluminum liquid, a thermocouple is inserted into the interior of the melting furnace from the corresponding temperature measuring hole 14 to detect the temperature of the liquid surface of the molten aluminum liquid. When the temperature reaches 700-730°C, a sampling tool is used to take a sample from the operating port 11, and after sampling, the sample is weighed, and then a spectrometer is used to analyze the content of each element in the sample.

[0046] Adding the metal silicon to be tested: 13 kg of metal silicon is randomly taken from the metal silicon pile to be tested and put into the melting furnace for melting for 60-90 minutes. During the melting process, the heating power of the melting furnace is adjusted according to the detection results of the thermocouple to keep the temperature of the molten aluminum liquid at 780-800°C, and the melting furnace is stirred every 20 minutes.

[0047] Second sampling: sample from the operation port 11 using sampling tools, after sampling, weigh the sample, and then use the spectrometer to analyze the content of each element in the sample.

[0048] Ingot casting: After standing for 10 minutes, reduce the furnace heating power to reduce the temperature of the molten aluminum in the furnace, control the cooling rate to be 20-30°C / min, and slowly reduce the temperature of the molten aluminum in the furnace from 780-800°C to 700-720°C, then open the valve at the liquid outlet 13, and discharge the silicon-containing aluminum liquid in the furnace from the liquid outlet 13, and cast the discharged silicon-containing aluminum liquid into aluminum-silicon alloy ingots, and after cooling, weigh them.

[0049] Put the identification plate: put the identification plate 2 into the center area of the aluminum liquid at the bottom of the furnace from the operation port 11 with the vertical identification block 21 upwards, collect the silicon-containing aluminum liquid overflowing from the liquid outlet 13 during this process, and after cooling, weigh it. Since the identification plate 2 has a density of 2.7-2.8 g / cm 3 , which is slightly higher than the density of molten aluminum with 11% silicon content, the plate will naturally sink to the vicinity below the high-purity silicon-containing aluminum liquid layer after being put into the furnace bottom. The content of metallic silicon impurities generally does not exceed 5%, so at this time the surface of the aluminum liquid at the bottom of the furnace is generally a high-purity silicon-containing aluminum liquid layer, and the ceramic heat insulation identification plate 2 naturally sinks to the vicinity below the high-purity silicon-containing aluminum liquid layer, i.e. sinks to the center area below the surface of the aluminum liquid at the bottom of the furnace.

[0050] Cooling of the aluminum liquid at the bottom of the furnace: use a thermocouple to detect the temperature of the molten aluminum at the edge of the furnace bottom from the lowest temperature measuring hole 14, continue to reduce the heating power of the furnace to reduce the temperature of the molten aluminum at the edge of the furnace bottom, control the cooling rate to be 20-30°C / min, and slowly reduce the temperature of the molten aluminum from 700-720°C to 660-665°C. Since the ceramic heat insulation identification plate 2 blocks the vertical heat conduction in the center area of the aluminum liquid at the bottom of the furnace, the center area of the surface of the aluminum liquid at the bottom of the furnace can only obtain heat from the edge area through horizontal heat conduction, so the temperature of the center area of the surface of the aluminum liquid at the bottom of the furnace is lower than that of the edge area, and it will continue to solidify to form a silicon-containing aluminum block, thereby forming a silicon-containing aluminum block layer in the center area of the surface of the aluminum liquid at the bottom of the furnace. The silicon-containing aluminum block layer is located above the identification plate 2 and belongs to high-purity silicon-containing aluminum material.

[0051] Collecting the silicon-aluminum block above the identification plate: After the silicon-aluminum block layer is formed in the center area of the liquid surface of the aluminum liquid at the bottom of the furnace, the liquid surface is observed from the operating port 11 first to confirm that the identification block 21 of the identification plate 2 has not floated above the liquid surface. The closing door of the slag removal port 12 is opened, and the long-handled iron hook / long-handled shovel is used to collect the silicon-aluminum block layer in the center area of the liquid surface of the aluminum liquid at the bottom of the furnace from the slag removal port 12. After one layer is collected, the aluminum liquid in the area is allowed to solidify again to form a new silicon-aluminum block layer, and the next collection operation is performed. After performing the collection operation for 3-5 times, the liquid surface is observed from the operating port 11 again; if the identification block 21 has not floated above the liquid surface, it can be confirmed that the current liquid surface belongs to the silicon-aluminum liquid layer with high purity, and the collection can be performed, so the operator continues to perform the collection operation for 3-5 times, and then the liquid surface is observed from the operating port 11 again, and so on, until the identification block 21 floats to the liquid surface. When the operator observes that the identification block floats to the liquid surface, it is 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, so the collection is stopped, and then the collected silicon-aluminum block is weighed. Compared with the existing technology which is only based on experience and subjective judgment by naked eyes, the present method can effectively reduce the error in the calculation of the recovery rate.

[0052] Calculating the recovery rate of metallic silicon: the weight of the cast aluminum-silicon alloy ingot, the silicon-aluminum liquid overflowed from the liquid outlet 13, the collected silicon-aluminum material, and the second sampling sample are added together to calculate the weight of the output aluminum-silicon alloy, the weight of the input aluminum ingot and metallic silicon is added together, the weight of the scraped dross and the first sampling sample is subtracted to calculate the weight of the input aluminum-silicon, and the weight of the output aluminum-silicon alloy is divided by the weight of the input aluminum-silicon to calculate the recovery rate of metallic silicon. The following is an example:

[0053] The weight of the scraped dross 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 overflowed 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 block is 5 kg, so 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 the recovery rate of metallic silicon is calculated, whether the content of iron and calcium in the metallic silicon meets the standard can be calculated according to the analysis results of the two sampling, which is illustrated in the following example.

[0056] The national standard for the metallic silicon 551 is that the content of iron is less than 0.5%, the weight of the sample is 0.5 kg in the first sampling analysis, and the content of iron is 0.00002%, the content of iron in the sample is 0.0005% in the second sampling analysis, so the content of iron in the metallic silicon is:

[0057]

(100-0.5+13)×0.0005

(100-0.5)×0.00002

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

[0059] The method for calculating the calcium content in metallic silicon is the same as that for calculating the iron content, and will not be repeated here.

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

[0061] In other embodiments, the three steps of slag scraping, first sampling, and second sampling are omitted. When calculating the recovery rate of metallic silicon, the weights of the cast aluminum-silicon alloy ingot, the silicon-containing aluminum liquid overflowing from the outlet 13, and the collected silicon-containing aluminum material are added together to calculate the weight of the produced aluminum-silicon alloy. The weights of the input aluminum ingot and metallic silicon are added together to calculate the weight of the input aluminum-silicon. The weight of the produced aluminum-silicon alloy is divided by the weight of the input aluminum-silicon to calculate the recovery rate of metallic silicon.

[0062] In other embodiments: In the step of placing the label plate, the label plate 2 is placed into any area of ​​the molten aluminum at the bottom of the furnace with the vertical label block 21 facing upwards from the operation port 11; after 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 label plate 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 block above the label plate, it is correspondingly changed to collecting the silicon-containing aluminum block layer formed by the solidification of the area above the label plate on the surface of the molten aluminum at the bottom of the furnace.

[0063] The above description is merely an embodiment of the present invention and does not limit the scope of patent protection. Any non-substantial changes or substitutions made by those skilled in the art based on the present invention will still fall within the scope of patent protection.

Claims

1. A method for detecting the recovery rate of metallic silicon, comprising the following steps executed in sequence: aluminum ingot smelting: putting aluminum ingots into a smelting furnace for smelting; adding metallic silicon to be detected: randomly taking metallic silicon from a pile of metallic silicon to be detected and putting it into the smelting furnace for smelting; casting into ingots: the bottom edge of the liquid outlet of the smelting furnace is higher than the bottom of the smelting furnace, the silicon-containing aluminum liquid in the smelting furnace is discharged from the liquid outlet, and the discharged silicon-containing aluminum liquid is cast into aluminum silicon alloy ingots, which are cooled and weighed; putting in an identification plate: putting an identification plate with a vertical identification block into the center area of the aluminum liquid at the bottom of the smelting furnace with the vertical identification block upward, the identification plate naturally sinks below the center area of the aluminum liquid surface at the bottom of the smelting furnace, collecting the silicon-containing aluminum liquid overflowing from the liquid outlet during this process, and weighing the collected silicon-containing aluminum liquid after cooling; collecting silicon-containing aluminum material above the identification plate: observing the liquid level, confirming that the identification block of the identification plate does not float above the liquid level, collecting the silicon-containing aluminum material above the identification plate until the identification block of the identification plate floats to the liquid level, and weighing the collected silicon-containing aluminum material; calculating the recovery rate of metallic silicon: adding 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, calculating the weight of the output aluminum silicon alloy, adding the weights of the input aluminum ingots and the metallic silicon, calculating the weight of the input aluminum silicon, and calculating the recovery rate of the metallic silicon by dividing the weight of the output aluminum silicon alloy by the weight of the input aluminum silicon. 2.The method according to claim 1, wherein: the identification plate put in is a heat insulation identification plate; a step of lowering the temperature of the aluminum liquid at the bottom of the smelting furnace is executed after the step of putting in the identification plate and before the step of collecting aluminum material above the identification plate: the heating power of the smelting furnace is lowered to reduce the temperature of the aluminum liquid at the bottom of the smelting furnace; in the step of collecting aluminum material above the identification plate, an aluminum block layer solidified in the area above the heat insulation identification plate at the liquid level of the aluminum liquid at the bottom of the smelting furnace is collected.

3. The method of claim 2, wherein: The heat insulation identification plate put in is a heat insulation identification plate with a vertical identification block at the edge. 4.The method according to claim 3, wherein: in the step of putting in the identification plate, the heat insulation identification plate is put into the center area of the aluminum liquid at the bottom of the smelting furnace; in the step of lowering the temperature of the aluminum liquid at the bottom of the smelting furnace, a thermocouple is used to detect the temperature of the aluminum liquid at the edge of the bottom of the smelting furnace, and the heating power of the smelting furnace is lowered to reduce the temperature of the aluminum liquid at the bottom of the smelting furnace, specifically to reduce the temperature of the aluminum liquid to 660-665 ℃.

5. The method of claim 2, wherein: The heat insulation identification plate put in is a ceramic heat insulation identification plate. 6.The method according to claim 5, wherein: the ceramic heat insulation identification plate is prepared before the step of smelting the aluminum ingots, comprising the following steps: mixing raw materials: uniformly mixing 68-72% of alumina powder, 26-30% of polystyrene microspheres, and 2% of PVA binder together; dry pressing: using a steel mold and a graphite bottom plate to press a plurality of circular green compacts with a diameter of 600-900 mm and a thickness of 8-10 mm under a pressure of 200 MPa, and the identification block with a height of 10-15 mm and a diameter of 50 mm is integrally formed at the top edge of the green compact; debinding: placing the green compact in a high-temperature environment of 400-600 ℃ for 1-2 hours to remove the polystyrene microspheres. Sintering: after debinding, the embryo is placed in a high temperature environment of 1400-1500℃ for 1-2 hours, so that the alumina particles are sintered and dense, the pores formed in situ by the microspheres are retained, and finally a ceramic thermal insulation identification plate with a porosity of 30-35% is formed; Density measurement: the density of the ceramic thermal insulation identification plate is measured using the Archimedes method, and the ceramic thermal insulation identification plate with a density of 2.7-2.8 g / cm³ is selected for subsequent use.

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