Preparation method for purifying calcium hydrophosphate

Abstract

The invention relates to the technical field of preparation of calcium hydrophosphate, discloses a preparation method for purifying calcium hydrophosphate, and solves the problems that in the existing preparation process of calcium hydrophosphate, calcium hydrophosphate often needs to be prepared through various steps, and the prepared calcium hydrophosphate is relatively high in acidity and contains excessive impurities after being dried. The effect of preparing high-purity calcium hydrogen phosphate is realized, and the preparation precision is also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of calcium hydrogen phosphate preparation, and specifically to a preparation method for purifying calcium hydrogen phosphate. Background Art

[0002] Calcium hydrogen phosphate is a white monoclinic crystalline powder, odorless and tasteless. It usually exists in the form of dihydrate, is stable in air, and begins to lose crystal water to become anhydrous when heated to 75 °C. The uses of calcium hydrogen phosphate are as follows: First, it is used as a fortifier and leavening agent; second, it is used as a food and feed additive; third, it is used as a leavening agent in the food industry; fourth, it is used as an auxiliary feed for poultry, which can promote body metabolism, enhance physical fitness, prevent osteoporosis, etc.

[0003] Calcium hydrogen phosphate contains a large amount of calcium element, and can effectively supplement the calcium required by the human body after taking. Calcium is one of the essential minerals in the human body and plays an important role in bone growth and maintenance, nerve conduction, muscle contraction, and blood coagulation mechanism. Calcium hydrogen phosphate can also assist in the treatment of some diseases related to calcium metabolism, such as hypocalcemia caused by kidney diseases. By supplementing calcium, the symptoms of patients can be improved and the quality of life can be enhanced.

[0004] For example, the application number CN202111654711.7 discloses a preparation method of high-purity calcium hydrogen phosphate, which is characterized in that: the production steps are neutralization stirring - precipitation - solid-liquid separation - drying. The neutralization stirring selects dilute phosphoric acid and lime milk, and the dilute phosphoric acid and lime milk are controlled-temperature stirred and neutralized to obtain a slurry containing calcium hydrogen phosphate. The precipitation is to put the slurry containing calcium hydrogen phosphate into a clarifier for precipitation, and the solid-liquid separation is carried out through a plate and frame filter press to obtain a calcium hydrogen phosphate cake, and then it is dried through a dryer to obtain calcium hydrogen phosphate, which has the characteristic of greatly reducing the production cost of high-purity calcium hydrogen phosphate. In the process of preparing the existing calcium hydrogen phosphate, it often needs to be prepared through numerous steps, and after drying, the prepared calcium hydrogen phosphate has a high acidity and contains too many impurities.

[0005] In view of the above problems, a preparation method for purifying calcium hydrogen phosphate is proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method for purifying calcium hydrogen phosphate, and this device is used for working, thereby solving the problems that in the process of preparing the existing calcium hydrogen phosphate, it often needs to be prepared through numerous steps, and after drying, the prepared calcium hydrogen phosphate has a high acidity and contains too many impurities.

[0007] To achieve the above purpose, the present invention provides the following technical solution: A preparation method for purifying calcium hydrogen phosphate, including the following steps:

[0008] Step 1: Filter the impurities from the crude phosphoric acid obtained by decomposing medium and low-grade phosphate rock with hydrochloric acid. Let it stand for five minutes. Add a fusion extractant to the filtrate. Pour the filtrate and the fusion extractant into an extraction purification oscillator for processing. Oscillate and extract for 30 to 40 minutes at 30 to 40 °C and a rotation speed of 200 to 350 revolutions per minute. Let it stand for layer separation. Use an extractor for further extraction, and then concentrate it under vacuum to obtain purified phosphoric acid, which is reserved for use.

[0009] Step 2: Add phosphorus pentasulfide to the purified phosphoric acid in an amount two to three times the measured mass of arsenic. React under stirring in a closed environment at 50 °C for two hours, then filter. Then, transport the filtrate to a hydrogen sulfide removal tower to remove hydrogen sulfide to obtain refined phosphoric acid, which is reserved for use.

[0010] Step 3: Clean the crude limestone with an ultrasonic cleaner. Control the adjustment frequency of the ultrasonic cleaner between 20,000 Hz and 40,000 Hz. After cleaning, place it in a calcination furnace for calcination treatment to obtain refined calcium oxide. Grind the refined calcium oxide into powder, then add deionized water and stir. Filter to remove slag to obtain refined lime milk, which is reserved for use.

[0011] Step 4: Take the refined phosphoric acid from Step 2 and stir it. Then, while stirring, add the refined lime milk from Step 3 in a mass ratio of refined phosphoric acid to refined lime milk of 1:3. After adding the materials, continue to stir and react for 50 minutes to 1 hour. Let the resulting slurry stand for precipitation, then separate the supernatant. Re-add deionized water and stir for 20 minutes, let it stand, and separate the supernatant again. Repeat this process three to four times. Then, dehydrate and separate the precipitate to obtain calcium hydrogen phosphate.

[0012] Step 5: Classify the calcium hydrogen phosphate using a vortex air classifier. When classifying, the fan flow rate of the vortex air classifier is 30 to 45 cubic meters per minute, and the rotation speed of the classification wheel of the vortex air classifier is 2,700 to 3,800 revolutions per minute to obtain calcium hydrogen phosphate fine powder with a particle size not greater than 7.5 microns. Then, perform secondary classification on the semi-finished calcium hydrogen phosphate fine powder using an impeller air classifier. The fan flow rate of the impeller air classifier is 12 to 28 cubic meters per minute, and the rotation speed of the classification wheel of the impeller air classifier is 1,200 to 1,900 revolutions per minute. Weigh and pack.

[0013] Preferably, the volume ratio of the filtrate to the fusion extractant in Step 1 is 1:3. The fusion extractant includes 30% triisobutyl phosphate, 15% ethyl butyl ether, and 35% cyclohexanone by volume percentage.

[0014] Preferably, the rotation speed of the extractor for oscillating extraction in Step 1 is 200 revolutions per minute.

[0015] Preferably, the ultrasonic cleaning in step three takes 20 to 30 minutes. After cleaning, it is dried. The coarsely ground limestone is placed inside the calcination furnace, and the temperature and time are controlled at 400 °C for 40 minutes, then heated to 650 °C for 30 minutes, and then further heated to 800 °C for 10 minutes.

[0016] Preferably, the stirring time of adding deionized water in step three is controlled at 40 to 50 minutes, and the rotation speed of the stirrer is controlled at 200 to 300 revolutions per minute. Among them, the total mass ratio of refined calcium oxide to deionized water is 1:2.5.

[0017] Preferably, the preparation process of the coarsely ground limestone in step three includes: using one or more of eggshells, shrimp and crab shells, and animal bones as the calcium source, washing the surface sludge and impurities with clean water using a washing machine, then soaking in a disinfectant for 10 minutes. The disinfectant is 75% alcohol, and then washing again with clean water. The cleaned calcium source is freeze-dried for 3 hours, and then coarsely ground and finely ground in sequence to obtain the coarsely ground limestone.

[0018] Preferably, the steps of dehydrating and separating the precipitate include placing the supernatant inside the drying oven, setting the temperature of the drying oven to dry at a temperature below 120 °C, and the drying time is 30 minutes.

[0019] Preferably, the air flow rate of the fan in step five is 40 cubic meters per minute, and the rotation speed of the classification wheel of the vortex air classifier is 4000 revolutions per minute.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. A preparation method for purifying calcium hydrogen phosphate proposed in this application solves the problems that in the existing preparation process of calcium hydrogen phosphate, numerous steps are often required for its preparation, and the calcium hydrogen phosphate after preparation has a high acidity and contains excessive impurities after drying. Before preparing calcium hydrogen phosphate, crude phosphoric acid can be prepared by decomposing medium and low-grade phosphate rock with hydrochloric acid. After filtering the crude phosphoric acid, it can be extracted by extraction. Pour the filtrate and the fused extractant into an extraction purification oscillator for processing, and oscillate and extract for 30 to 40 minutes at 30 to 40 °C and a rotation speed of 200 to 350 revolutions per minute, then let it stand for stratification, and use an extractor for further extraction. Then, concentrate it under vacuum to obtain purified phosphoric acid. Add phosphorus pentasulfide to the purified phosphoric acid in an amount two to three times the measured mass of arsenic, and react under stirring in a closed environment at 50 °C for two hours, then filter. Then, transport the filtrate to a hydrogen sulfide removal tower to remove hydrogen sulfide to obtain refined phosphoric acid and reserve it. Then, use one or more of eggshells, shrimp and crab shells, and animal bones as the calcium source. Wash them with clean water using a washing machine to remove surface sludge and impurities, then soak them in a disinfectant for ten minutes. The disinfectant is 75% ethanol, and wash them with clean water again. Freeze-dry the washed calcium source for three hours, and then perform coarse grinding and fine grinding in sequence to obtain crude limestone. This step facilitates the recycling of some kitchen waste, improves the protection effect on the ecological environment and reduces production costs at the same time. After the cleaning and calcination operations, refined lime milk can be obtained. Mix the refined lime milk with the refined phosphoric acid, and continue to stir and react for 50 minutes to one hour after the feeding is completed; let the generated homogenate stand for precipitation, then separate the supernatant, add deionized water again and stir for 20 minutes, let it stand, and separate the supernatant again. Repeat this three to four times; then, dehydrate and separate the precipitate to obtain calcium hydrogen phosphate, realizing the function of being able to obtain high-purity calcium hydrogen phosphate and improving the preparation accuracy.

[0022] 2. A preparation method for purifying calcium hydrogen phosphate proposed in this application solves the problem that after the existing calcium hydrogen phosphate is prepared, it is often inconvenient to classify the particle size of calcium hydrogen phosphate, resulting in an impact on the subsequent bagging process. Pour the prepared calcium hydrogen phosphate and its aqueous solution into the inside of a drying oven, set the temperature of the drying oven to dry at a temperature below 120 °C, and the drying time is 30 minutes. Use a vortex air classifier to classify the calcium hydrogen phosphate. When classifying, the fan flow rate of the vortex air classifier is 30 to 45 cubic meters per minute, and the rotation speed of the classification wheel of the vortex air classifier is 2,700 to 3,800 revolutions per minute to obtain calcium hydrogen phosphate fine powder with a particle size not greater than 7.5 microns. Then, perform secondary classification on the semi-finished calcium hydrogen phosphate fine powder using an impeller air classifier. The fan flow rate of the impeller air classifier is 12 to 28 cubic meters per minute, and the rotation speed of the classification wheel of the impeller air classifier is 1,200 to 1,900 revolutions per minute. At this time, the calcium hydrogen phosphate fine powder with different particle sizes after classification can be weighed, bagged, etc., realizing the function of quickly classifying the particle size of calcium hydrogen phosphate and improving the subsequent work process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of the overall process of the present invention;

[0024] Figure 2 is a schematic diagram of the composition of the fusion extractant of the present invention;

[0025] Figure 3 is a schematic diagram of the preparation process of the limestone raw material of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] To further understand the content of the present invention, the present invention will be described in detail with reference to the accompanying drawings.

[0028] Combined with Figures 1 - 3 , a preparation method for purifying calcium hydrogen phosphate includes the following steps:

[0029] Step 1: Filter the impurities from the crude phosphoric acid obtained by decomposing medium and low grade phosphate rock with hydrochloric acid. Let it stand for five minutes. Add the fusion extractant to the filtrate, pour the filtrate and the fusion extractant into an extraction purification oscillator for processing, and oscillate and extract for 30 to 40 minutes at 30 to 40 °C and a rotation speed of 200 to 350 revolutions per minute. Let it stand for stratification, use an extractor for further extraction, and then concentrate under vacuum to obtain purified phosphoric acid for standby;

[0030] Step 2: Add phosphorus pentasulfide to the purified phosphoric acid in an amount two to three times the measured mass of arsenic, and react with stirring in a closed environment at 50 °C for two hours, then filter. Then, transport the filtrate to a hydrogen sulfide removal tower to remove hydrogen sulfide to obtain refined phosphoric acid for standby;

[0031] Step 3: Clean the crude limestone with an ultrasonic cleaner, control the adjustment frequency of the ultrasonic cleaner between 20,000 Hz and 40,000 Hz. After cleaning, place it in a calcination furnace for calcination to obtain refined calcium oxide; grind the refined calcium oxide into powder, then add deionized water for stirring operation, filter to remove slag, and obtain refined lime milk for standby;

[0032] Step 4: Take the refined phosphoric acid from Step 2 and stir it, then add the refined lime milk from Step 3 while stirring according to the mass ratio of refined phosphoric acid to refined lime milk of 1:3. After adding the materials, continue to stir and react for 50 minutes to 1 hour; let the generated slurry stand for precipitation, then separate the supernatant, re-add deionized water and stir for 20 minutes, let it stand, and separate the supernatant again. Repeat this process three to four times; then, dehydrate and separate the precipitate to obtain calcium hydrogen phosphate;

[0033] Step 5: Use a vortex air classifier to classify the calcium hydrogen phosphate. When classifying, the fan flow rate of the vortex air classifier is 30 to 45 cubic meters per minute, and the rotation speed of the classification wheel of the vortex air classifier is 2,700 to 3,800 revolutions per minute to obtain calcium hydrogen phosphate fine powder with a particle size not greater than 7.5 microns. Then, perform secondary classification on the calcium hydrogen phosphate fine powder semi-finished product with an impeller air classifier. The fan flow rate of the impeller air classifier is 12 to 28 cubic meters per minute, and the rotation speed of the classification wheel of the impeller air classifier is 1,200 to 1,900 revolutions per minute. Weigh and pack.

[0034] In Step 1, the volume ratio of the filtrate to the fusion extractant is 1:3. The fusion extractant includes 30% triisobutyl phosphate, 15% ethyl butyl ether, and 35% cyclohexanone by volume percentage.

[0035] In Step 1, the rotation speed of the extractor for oscillating extraction is 200 revolutions per minute.

[0036] In Step 3, the ultrasonic cleaning takes 20 to 30 minutes. After cleaning, it is dried. The crude limestone product after cleaning is placed inside the calcination furnace, and the temperature and time are controlled as follows: calcined at 400 °C for 40 minutes, heated to 650 °C and calcined for 30 minutes, and then heated to 800 °C and calcined for 10 minutes.

[0037] In Step 3, the stirring time with deionized water added is controlled at 40 to 50 minutes, and the rotation speed of the stirrer is controlled at 200 to 300 revolutions per minute. Among them, the total mass ratio of refined calcium oxide to deionized water is 1:2.5.

[0038] The preparation process of the crude limestone product in Step 3 includes: using one or more of eggshells, shrimp and crab shells, and animal bones as the calcium source, washing with clean water using a washing machine to remove surface sludge and impurities, then soaking in a disinfectant for 10 minutes. The disinfectant uses 75% concentration alcohol, washing again with clean water, freeze-drying the calcium source after cleaning for 3 hours, and then performing coarse grinding and fine grinding in sequence to obtain the crude limestone product.

[0039] The steps for dehydration and separation of the precipitate include placing the supernatant inside the drying oven, setting the temperature of the drying oven to dry at a temperature below 120 °C, and the drying time is 30 minutes.

[0040] In Step 5, the blower flow rate is 40 cubic meters per minute, and the rotation speed of the classification wheel of the vortex air classifier is 4000 revolutions per minute.

[0041] The present invention will be further described below in conjunction with embodiments.

[0042] Embodiment 1:

[0043] To solve the problems that in the preparation of existing calcium hydrogen phosphate, it often requires a large number of steps to prepare calcium hydrogen phosphate, and after drying the prepared calcium hydrogen phosphate, it has a high acidity and contains too many impurities, this embodiment discloses the following technical solutions, specifically as Figures 1 - 3As shown in the figure, before preparing calcium hydrogen phosphate, crude phosphoric acid can be prepared by decomposing medium and low-grade phosphate rock with hydrochloric acid. After filtering the crude phosphoric acid, it can be extracted by extraction. Pour the filtrate and the fused extractant into an extraction purification oscillator for processing, and oscillate and extract for 30 to 40 minutes at 30 to 40 °C and a rotation speed of 200 to 350 revolutions per minute. Let it stand for stratification, and use an extractor for further extraction. Then concentrate it under vacuum to obtain purified phosphoric acid. Add phosphorus pentasulfide to the purified phosphoric acid in an amount two to three times the measured arsenic mass, and react with stirring for two hours in a closed environment at 50 °C, then filter. Then transport the filtrate to a hydrogen sulfide removal tower to remove hydrogen sulfide to obtain refined phosphoric acid and reserve it. Then, use one or more of eggshells, shrimp and crab shells, and animal bones as the calcium source. Use a cleaning machine to wash it with clean water to remove surface sludge and impurities, and then soak it in a disinfectant for ten minutes. The disinfectant is 75% alcohol. Wash it again with clean water. Freeze-dry the cleaned calcium source for three hours, and then perform coarse grinding and fine grinding in sequence to obtain crude calcium carbonate. This step facilitates the recycling of some kitchen waste, improves the protection effect on the ecological environment and reduces the production cost at the same time. After the cleaning and calcination operations, refined lime milk can be obtained. Mix the refined lime milk with the refined phosphoric acid, and continue to stir and react for 50 minutes to one hour after the feeding is completed; let the generated slurry stand for precipitation and then separate the supernatant, add deionized water again and stir for 20 minutes, let it stand, and separate the supernatant again, and repeat three to four times; then, dehydrate and separate the precipitate to obtain calcium hydrogen phosphate, realizing the function of being able to obtain high-purity calcium hydrogen phosphate, and also improving the preparation accuracy.

[0044] At the same time, to solve the problem that after the existing calcium hydrogen phosphate is prepared, it is often not convenient to classify the particle size of calcium hydrogen phosphate, resulting in an impact on the subsequent packaging process, this embodiment also discloses the following solution: Pour the prepared calcium hydrogen phosphate and its aqueous solution into the interior of a drying oven, set the temperature of the drying oven to dry at a temperature below 120 °C, and the drying time is 30 minutes. Use a vortex air classifier to classify calcium hydrogen phosphate. When classifying, the fan flow rate of the vortex air classifier is 30 to 45 cubic meters per minute, and the rotation speed of the classification wheel of the vortex air classifier is 2,700 to 3,800 revolutions per minute to obtain calcium hydrogen phosphate fine powder with a particle size not greater than 7.5 microns. Then, perform secondary classification on the calcium hydrogen phosphate fine powder semi-finished product with an impeller air classifier. The fan flow rate of the impeller air classifier is 12 to 28 cubic meters per minute, and the rotation speed of the classification wheel of the impeller air classifier is 1,200 to 1,900 revolutions per minute. At this time, the calcium hydrogen phosphate fine powder with different particle sizes after classification can be weighed, packaged, etc., realizing the function of being able to quickly classify the particle size of calcium hydrogen phosphate and improving the subsequent work process.

[0045] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0046] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method for purifying calcium hydrogen phosphate, characterized in that: The steps include: Step 1, filtering impurities from crude phosphoric acid obtained by decomposing low-grade phosphate ore with hydrochloric acid, leaving it for five minutes, adding a fusion extractant to the filtrate, pouring the filtrate and the fusion extractant into an extraction purification oscillator for processing, and oscillating and extracting for thirty to forty minutes at a temperature of thirty to forty degrees Celsius and a rotation speed of two hundred to three hundred and fifty revolutions per minute, standing for stratification, further extracting using an extractor, and then concentrating under vacuum to obtain purified phosphoric acid for standby use; Step 2, adding phosphorus pentasulfide at a rate of two to three times the mass of the measured arsenic to the purified phosphoric acid, stirring and reacting for two hours at 50 degrees in a closed environment, filtering, and then conveying the filtrate to a hydrogen sulfide removal tower to remove hydrogen sulfide to obtain refined phosphoric acid, which is then set aside; Step 3: Clean the crude limestone with an ultrasonic cleaner, control the frequency of the ultrasonic cleaner to be between 20,000 Hz and 40,000 Hz, place it in a calcining furnace for calcination after cleaning to obtain refined calcium oxide; ball-grind the refined calcium oxide into powder, then add deionized water for stirring, filter and remove slag to obtain refined lime milk for standby use; Step 4, taking the refined phosphoric acid of step 2 and stirring it, then adding the refined lime milk of step 3 in a mass ratio of refined phosphoric acid to refined lime milk of 1:3 while stirring, and continuing to stir and react for 50 minutes to 1 hour after the addition is completed; after the generated homogenate is allowed to stand and settle, the supernatant is separated, deionized water is added again and stirred for 20 minutes, and the mixture is allowed to stand and the supernatant is separated again, and the process is repeated three to four times; then, the precipitate is dehydrated and separated to obtain calcium hydrogen phosphate; Step 5, using a vortex airflow classifier to classify the calcium hydrogen phosphate, the fan flow rate of the vortex airflow classifier during classification is 30 to 45 cubic meters per minute, the classification wheel speed of the vortex airflow classifier is 2,700 to 3,800 revolutions per minute, to obtain calcium hydrogen phosphate micropowder with a particle size not greater than 7.5 microns, and then the calcium hydrogen phosphate micropowder semi-finished product is subjected to secondary classification by an impeller airflow classifier, the fan flow rate of the impeller airflow classifier is 12 to 28 cubic meters per minute, the classification wheel speed of the impeller airflow classifier is 1,200 to 1,900 revolutions per minute, weighing and packaging.

2. A method for preparing calcium hydrogen phosphate purification according to claim 1, characterized in that: The volume ratio of the filtrate in step 1 to the fusion extractant is 1:3, and the fusion extractant includes 30% triisobutyl phosphate, 15% ethyl butyl ether and 35% cyclohexanone by volume.

3. A method for preparing calcium hydrogen phosphate purification according to claim 1, characterized in that: The rotation speed of the extractor for oscillation extraction in step 1 is 200 revolutions per minute.

4. A method for preparing calcium hydrogen phosphate purification according to claim 1, characterized in that: The ultrasonic cleaning in step 3 takes 20 to 30 minutes, and after cleaning, the crude limestone is dried. The cleaned crude limestone is placed inside a calcining furnace, and the temperature and time are controlled at 400 degrees Celsius for calcining for 40 minutes, then raised to 650 degrees Celsius for calcining for 30 minutes, and then raised to 800 degrees Celsius for calcining for 10 minutes.

5. A method for preparing calcium hydrogen phosphate purification according to claim 1, characterized in that: In the step three, the time for adding deionized water for stirring is controlled at 40 to 50 minutes, and the speed of the stirrer is controlled at 200 to 300 revolutions per minute, wherein the total mass ratio of refined calcium oxide to deionized water is 1 to 2.

5.

6. A method for preparing calcium hydrogen phosphate purification according to claim 1, characterized in that: The preparation process of the crude limestone in step three includes: using one or more of egg shells, shrimp and crab shells and animal bones as a calcium source, using a cleaning machine to wash with clean water to remove surface sludge and impurities, and then soaking in a disinfectant for ten minutes, the disinfectant uses 75% alcohol concentration, and washing again with clean water, freeze-drying the cleaned calcium source for three hours, and then coarse grinding and fine grinding in sequence to obtain a crude limestone.

7. A method for preparing calcium hydrogen phosphate purification according to claim 1, characterized in that: The step of dehydrating and separating the precipitate includes placing the clear liquid inside a drying box, setting the temperature of the drying box to below 120 degrees Celsius for drying, and the drying time is 30 minutes.

8. A method for preparing purified calcium hydrogen phosphate according to claim 1, characterized in that: In step 5, the fan flow rate is 40 cubic meters per minute, and the classifying wheel speed of the vortex airflow classifier is 4,000 revolutions per minute.

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