Granulation waste powder separation and recovery method and pure ceramic powder

Abstract

The invention provides a granulation waste powder separation and recovery method and a pure ceramic powder, comprising the following steps: taking an appropriate amount of granulation waste powder and pouring it into a ball mill, adding alcohol and citric acid; adding grinding balls, ball milling under vacuum conditions, placing after ball milling, using ammonium polyacrylate to fully decompose after placing, and recirculating the following ball milling steps at least five times: ball milling under vacuum conditions, placing after ball milling, using ammonium polyacrylate to fully decompose after placing, and obtaining ball-milled slurry; performing rotary evaporation solid-liquid separation on the ball-milled slurry to obtain rotary evaporation dried powder; secondary rinsing of the rotary evaporation dried powder in isopropanol, and performing rotary evaporation solid-liquid separation on the secondary rinsing powder to obtain pure ceramic powder; organic matter in the waste powder can be effectively removed to obtain pure ceramic powder, which not only reduces the amount of organic matter residue in the recovered powder and meets the standard of secondary use, but also enables the waste powder resources to be effectively recovered and reused.

Description

Technical Field

[0001] The invention relates to the technical field of separation and recovery of granulation waste powder, and in particular to a separation and recovery method of granulation waste powder and pure ceramic powder. Background Art

[0002] Spray granulation technology, as a key technology in the field of modern industry, has been widely used in many cutting-edge fields such as chemistry, food, medicine, biochemistry, and material processing, greatly broadening the boundaries and potential of spray drying technology. This technology cleverly refines liquid raw materials into micron-sized droplets through a precise atomization device, and then achieves rapid evaporation and direct solidification of the droplets under the action of efficient hot air flow, thereby efficiently producing high-quality powder products. The spray drying process is carefully divided into three core stages: first, efficient atomization of the liquid to form a uniform and delicate droplet group; second, in-depth contact, full mixing and smooth flow of droplets and hot air to ensure rapid evaporation of water; finally, efficient separation of dried products and waste gas, which ensures product quality while also providing possibilities for subsequent processing.

[0003] However, during the separation stage, a problem that cannot be ignored emerges - some fine powders are often carried to the powder separation system by exhaust gas due to their ultra-fine particles, easy to float, and possible carrying of organic impurities. Although this part of fine powder is recycled, due to its inherent physical properties and complex chemical composition, it is traditionally considered difficult to use and can only be scrapped in the end. Although the overall production efficiency in the industry remains at a high level of 70% to 74%, this also means that in each batch of production, about 26 kg to 30 kg of fine powder is unfortunately abandoned. In the long run, the waste of resources and the increase in costs cannot be ignored.

[0004] Although attempts have been made to address the recycling problem of granulation waste powder, the traditional thermal degreasing process has significant limitations: on the one hand, the processing cycle is long and the degreasing time usually takes at least 24 hours, which seriously affects production efficiency; on the other hand, the process is complicated, and not only does the powder accumulation thickness need to be strictly controlled during the thermal degreasing process, but the granulation waste powder is generally finer in particle size and can be easily sucked away by hot air during the exhaust process, blocking the exhaust port of the thermal degreasing furnace and causing the thermal degreasing furnace to malfunction; furthermore, the traditional process performs poorly in removing organic matter from waste powder, resulting in a high level of organic residue in the recycled powder, which is difficult to meet the standards for secondary use, thus limiting the effective reuse of waste powder resources.

[0005] The disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application, nor does it necessarily provide technical guidance. In the absence of clear evidence that the above content has been disclosed before the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the invention

[0006] In order to solve the technical problems in the traditional thermal degreasing process for separating and recovering granulation waste powder, such as complex process, long treatment cycle, poor performance in removing organic matter in waste powder, resulting in high organic matter residue in recovered powder, and difficulty in meeting the standard for secondary use, the present invention proposes a granulation waste powder separation and recovery method and pure ceramic powder, which has a simple process and a short treatment cycle, can effectively remove organic matter in waste powder and obtain pure ceramic powder, which not only reduces the organic matter residue in the recovered powder and meets the standard for secondary use, but also enables the waste powder resources to be effectively recovered and reused.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] The present invention provides a method for separating and recovering granulation waste powder, comprising the following steps:

[0009] S1 takes an appropriate amount of granulation waste powder and pours it into a ball mill, and adds alcohol and citric acid;

[0010] S2 adds grinding balls, performs ball milling under vacuum conditions, leaves the milling aside, and uses ammonium polyacrylate to fully decompose the milling after leaving aside, and then repeats the following ball milling steps at least five times: performs ball milling under vacuum conditions, leaves the milling aside, and uses ammonium polyacrylate to fully decompose the milling after leaving aside, to obtain a ball milled slurry;

[0011] S3: The slurry after ball milling is subjected to rotary evaporation for solid-liquid separation to obtain a rotary dried powder;

[0012] S4: The powder after rotary evaporation drying is rinsed twice in isopropanol to obtain a powder after secondary rinsing, and the powder after secondary rinsing is subjected to rotary evaporation for solid-liquid separation to obtain pure ceramic powder.

[0013] The present invention proposes a method for separating and recycling granulation waste powder, which has a simple process and a short treatment cycle, and can effectively remove organic matter in the waste powder to obtain pure ceramic powder. This not only reduces the amount of organic matter residue in the recycled powder and meets the standard for secondary use, but also enables the waste powder resources to be effectively reused.

[0014] As a preferred technical solution, the concentration of the alcohol substance is 85% to 95%, and the alcohol substance includes: any one or two of ethanol and isopropanol.

[0015] As a preferred technical solution, the mass ratio of the granulation waste powder to the alcohol substance is 1:(1-2).

[0016] As a preferred technical solution, the mass ratio of the granulation waste powder to the citric acid is 1:(0.1-0.15).

[0017] As a preferred technical solution, the grinding balls are either or both of alumina balls or zirconia balls, and the mass ratio of the granulation waste powder to the grinding balls is 1:(2-3).

[0018] As a preferred technical solution, in step S2, the vacuum degree of the ball milling under the vacuum conditions is 0.09 MPa to 0.095 MPa, the time for the ball milling under the vacuum conditions is 25 min to 35 min, the rotation speed of the ball milling under the vacuum conditions is 45 rpm to 55 rpm, and the placement time after the ball milling is 30 min to 60 min.

[0019] As a preferred technical solution, in step S2, during the ball milling process, citric acid is added to provide an acidic environment so that the organic additives in the granulation waste powder can be fully dissolved, and ammonium polyacrylate is decomposed into polyacrylic acid and NH4+. NH4+ combines with water molecules and is extracted and removed in the form of NH3 under a vacuum environment.

[0020] As a preferred technical solution, the vacuum degree in a vacuum environment is 0.09 MPa to 0.095 MPa.

[0021] As a preferred technical solution, the rotary evaporation temperature for solid-liquid separation of the ball-milled slurry or the secondary rinsing of the powder after rotary evaporation in isopropanol is 35°C to 45°C, and the rotary evaporation speed for solid-liquid separation of the ball-milled slurry or the secondary rinsing of the powder after rotary evaporation in isopropanol is 5rpm to 15rpm.

[0022] The present invention also provides a pure ceramic powder, which is prepared according to any of the above-mentioned granulation waste powder separation and recovery methods.

[0023] The present invention provides a method for separating and recovering granulation waste powder and a pure ceramic powder, which has the following beneficial effects:

[0024] 1) The process is simple and the treatment cycle is short. It can effectively remove organic matter from waste powder and obtain pure ceramic powder. This not only reduces the amount of organic residue in the recycled powder and meets the standard for secondary use, but also makes the waste powder resources effectively reused;

[0025] 2) Add alcohol as a solvent to help dissolve or disperse the organic matter in the waste powder; add citric acid as a chelating agent to combine with the metal ions or other chelatable components in the organic matter to form a soluble chelate, thereby facilitating the removal of the organic matter;

[0026] The mechanical force during ball milling helps to break the bond between organic matter and ceramic powder, making it easier to separate the organic matter; ball milling under vacuum conditions helps to reduce oxidation reactions and protect the ceramic powder from further contamination;

[0027] Using ammonium polyacrylate as a decomposition agent to further promote the decomposition or dissolution of organic matter; the decomposition action includes chemical decomposition or physical dispersion, which helps to separate the organic matter from the ceramic powder;

[0028] The liquid in the slurry (including dissolved organic matter) is evaporated by rotary evaporation to achieve solid-liquid separation; this step helps to remove most of the residual organic matter and solvent;

[0029] Isopropyl alcohol is used as a rinse agent to further dissolve or clean the organic matter remaining on the surface of the ceramic powder. The isopropyl alcohol and the dissolved organic matter are removed again by rotary evaporation solid-liquid separation to obtain pure ceramic powder.

[0030] 3) During the ball milling process, the addition of citric acid to provide an acidic environment allows the organic additives in the granulation waste powder to be fully dissolved, and ammonium polyacrylate is decomposed into polyacrylic acid and NH4+. NH4+ combines with water molecules and is removed in the form of NH3 under a vacuum environment. On the one hand, citric acid, as an acidic substance, can lower the pH value of the environment, thereby creating an environment that is conducive to the dissolution of organic additives. Under acidic conditions, the solubility of many organic substances will increase, which allows the organic additives in the granulation waste powder to be more fully dissolved in the system. Through circulating ball milling, most of the organic matter in the waste powder is further dispersed and dissolved, providing convenience for subsequent treatment. On the other hand, the dissolved ammonium polyacrylate decomposes under the mechanical action of the ball mill. Ammonium polyacrylate is decomposed into polyacrylic acid and NH4+. NH4+ ions combine with water molecules. This The interaction is the attraction between the positive charge of the ammonium ion and the negative charge of the oxygen atom in the water molecule. However, in a vacuum environment, as the number of water molecules decreases, this interaction is weakened accordingly, making it easier for the ammonium ion to dissociate from the water molecules. In a vacuum environment, due to the extremely low pressure, any volatile substance is more likely to change from solid or liquid to gas; therefore, when the ammonium ion loses enough support from water molecules, it tends to be reconverted into ammonia and evaporate into the vacuum, which is easy to evaporate in the form of NH3 in a vacuum environment. The NH3 that is removed helps to remove impurities in the waste powder, especially those related to ammonium polyacrylate, thereby purifying the waste powder and improving the purity of the ceramic powder. Relatively pure ceramic powder can be obtained, and the organic additives can be extracted and treated in the form of NH3, which can also avoid their direct discharge into the environment to cause pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 EDS spectrum of ceramic powder prepared by traditional thermal degreasing process provided as background technology (Comparative Example 1);

[0032] Figure 2This is the EDS spectrum of the ceramic powder obtained in Comparative Example 2 after sintering;

[0033] Figure 3 This is the EDS spectrum of the pure ceramic powder prepared in Example 1 provided by the present invention; DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0035] The present invention provides a method for separating and recovering granulation waste powder, comprising the following steps:

[0036] S1 takes an appropriate amount of granulation waste powder and pours it into a ball mill, and adds alcohol and citric acid;

[0037] S2 adds grinding balls, performs ball milling under vacuum conditions, leaves the milling aside, and uses ammonium polyacrylate to fully decompose the milling after leaving aside, and then repeats the following ball milling steps at least five times: performs ball milling under vacuum conditions, leaves the milling aside, and uses ammonium polyacrylate to fully decompose the milling after leaving aside, to obtain a ball milled slurry;

[0038] S3: The slurry after ball milling is subjected to rotary evaporation for solid-liquid separation to obtain a rotary dried powder;

[0039] S4: The powder after rotary evaporation drying is rinsed twice in isopropanol to obtain a powder after secondary rinsing, and the powder after secondary rinsing is subjected to rotary evaporation for solid-liquid separation to obtain pure ceramic powder.

[0040] The present invention proposes a method for separating and recycling granulation waste powder, which has a simple process and a short treatment cycle, and can effectively remove organic matter in the waste powder to obtain pure ceramic powder. This not only reduces the amount of organic matter residue in the recycled powder and meets the standard for secondary use, but also enables the waste powder resources to be effectively reused.

[0041] Preferably, an alcohol is added as a solvent to help dissolve or disperse the organic matter in the waste powder; citric acid is added as a chelating agent to combine with metal ions or other chelatable components in the organic matter to form a soluble chelate, thereby facilitating the removal of the organic matter;

[0042] Preferably, the mechanical force during ball milling helps to break the bond between the organic matter and the ceramic powder, making it easier to separate the organic matter; ball milling under vacuum conditions helps to reduce oxidation reactions and protect the ceramic powder from further contamination;

[0043] Preferably, ammonium polyacrylate is used as a decomposition agent to further promote the decomposition or dissolution of organic matter; the decomposition action includes chemical decomposition or physical dispersion, which helps to separate the organic matter from the ceramic powder;

[0044] Preferably, the liquid (including dissolved organic matter) in the slurry is evaporated by rotary evaporation to achieve solid-liquid separation; this step helps to remove most of the residual organic matter and solvent;

[0045] Preferably, isopropyl alcohol is used as a rinse agent to further dissolve or clean the organic matter remaining on the surface of the ceramic powder, and the isopropyl alcohol and the dissolved organic matter are removed again by rotary evaporation solid-liquid separation to obtain pure ceramic powder.

[0046] The present invention provides a method for separating and recovering granulation waste powder, comprising the following steps:

[0047] S1: Take an appropriate amount of granulation waste powder and pour it into a ball mill, add alcohol and citric acid, the concentration of the alcohol is preferably 85-95%, and the concentration of the alcohol is preferably 85%, 90% and 95%. Due to space limitations and for simplicity, the present invention will no longer exhaustively list the specific point values ​​included in the range;

[0048] The mass ratio of the granulation waste powder to the citric acid is preferably 1: (0.1-0.15); the mass ratio of the granulation waste powder to the citric acid is preferably 1: 0.1, 1: 0.12 and 1: 0.15. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range;

[0049] The mass ratio of the granulation waste powder to the alcohol substance is preferably 1:(1-2), and the mass ratio of the granulation waste powder to the alcohol substance is preferably 1:1, 1:1.5 and 1:2. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range;

[0050] Preferably, the alcohol substance includes: any one or both of ethanol and isopropanol;

[0051] S2 adds grinding balls, performs ball milling under vacuum conditions, leaves the milling aside, and uses ammonium polyacrylate to fully decompose the milling after leaving aside, and then repeats the following ball milling steps at least five times: performs ball milling under vacuum conditions, leaves the milling aside, and uses ammonium polyacrylate to fully decompose the milling after leaving aside, to obtain a ball milled slurry;

[0052] Preferably, the grinding balls are either or both of alumina balls or zirconia balls;

[0053] The mass ratio of the granulation waste powder to the grinding balls is preferably 1:(2-3), and the mass ratio of the granulation waste powder to the grinding balls is preferably 1:2, 1:2.5 and 1:3. Due to space limitations and for the sake of simplicity, the present invention will no longer exhaustively list the specific point values ​​included in the range;

[0054] The vacuum degree of ball milling under the vacuum conditions is preferably 0.09 MPa to 0.095 MPa, and the vacuum degree of ball milling under the vacuum conditions is preferably 0.09 MPa, 0.092 MPa and 0.095 MPa. Due to space limitations and for simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range;

[0055] The time for ball milling under the vacuum condition is preferably 25 min to 35 min, and the time for ball milling under the vacuum condition is preferably 25 min, 30 min and 35 min. Due to space limitations and for the sake of simplicity, the present invention will no longer exhaustively list the specific point values ​​included in the range;

[0056] The speed of ball milling under the vacuum condition is preferably 45 rpm to 55 rpm, and the speed of ball milling under the vacuum condition is preferably 45 rpm, 50 rpm and 55 rpm. Due to space limitations and for the sake of simplicity, the present invention will no longer exhaustively list the specific point values ​​included in the range;

[0057] The time of placing after ball milling is preferably 30 min to 60 min, and the time of placing after ball milling is preferably 30 min, 40 min, 50 min and 60 min. Due to space limitations and for the sake of simplicity, the present invention will no longer exhaustively list the specific point values ​​included in the range;

[0058] Preferably, during the ball milling process, citric acid is added to provide an acidic environment so that the organic additives in the granulation waste powder can be fully dissolved, and ammonium polyacrylate is decomposed into polyacrylic acid and NH4+. NH4+ combines with water molecules and is removed in the form of NH3 under a vacuum environment. On the one hand, citric acid, as an acidic substance, can lower the pH value of the environment, thereby creating an environment that is conducive to the dissolution of organic additives. Under acidic conditions, the solubility of many organic substances will increase, which makes the organic additives in the granulation waste powder more fully dissolved in the system. Through the circulating ball milling, most of the organic substances in the waste powder are removed. The material is further dispersed and dissolved, which provides convenience for subsequent treatment; on the other hand, the dissolved ammonium polyacrylate decomposes under the mechanical action of the ball mill, and the ammonium polyacrylate is decomposed into polyacrylic acid and NH4+. The NH4+ ions combine with water molecules. This interaction is the attraction between the positive charge of the ammonium ion and the negative charge part of the oxygen atom in the water molecule. However, in a vacuum environment, as the water molecules decrease, this interaction is also weakened accordingly, making it easier for the ammonium ion to dissociate from the water molecules. In a vacuum environment, due to the extremely low pressure, any volatile substance is more likely to change from solid or liquid to gas. Therefore, when the ammonium ion loses enough support from water molecules, it tends to be converted back into ammonia and evaporate into the vacuum, which is easy to evaporate in the form of NH3 in a vacuum environment. The NH3 that is removed helps to remove impurities in the waste powder, especially those related to ammonium polyacrylate, thereby purifying the waste powder and improving the purity of the ceramic powder. Relatively pure ceramic powder can be obtained, and the organic additives can be extracted and treated in the form of NH3, which can also avoid being directly discharged into the environment to cause pollution;

[0059] The vacuum degree in a vacuum environment is preferably 0.09 MPa to 0.095 MPa, and the vacuum degree in a vacuum environment is preferably 0.09 MPa, 0.092 MPa and 0.095 MPa. Due to space limitations and for simplicity, the present invention will no longer exhaustively list the specific point values ​​included in the range;

[0060] S3: The slurry after ball milling is subjected to rotary evaporation for solid-liquid separation to obtain a rotary dried powder;

[0061] S4: The powder after rotary evaporation drying is rinsed twice in isopropanol to obtain a powder after secondary rinsing, and the powder after secondary rinsing is subjected to rotary evaporation for solid-liquid separation to obtain a pure ceramic powder;

[0062] The rotary evaporation temperature for the solid-liquid separation of the ball-milled slurry or the secondary rinsing of the powder after rotary evaporation in isopropanol is 35°C to 45°C, and the rotary evaporation speed for the solid-liquid separation of the ball-milled slurry or the secondary rinsing of the powder after rotary evaporation in isopropanol is 5rpm to 15rpm;

[0063] The rotary evaporation temperature for performing rotary evaporation solid-liquid separation on the ball-milled slurry or for secondary rinsing of the rotary dried powder in isopropanol is preferably 35° C., 40° C. and 45° C. Due to space limitations and for the sake of simplicity, the present invention will no longer exhaustively list the specific point values ​​included in the range;

[0064] The rotary evaporation speed for performing solid-liquid separation on the ball-milled slurry or for secondary rinsing of the rotary evaporation dried powder in isopropanol is preferably 5 rpm, 10 rpm and 15 rpm. Due to space limitations and for the sake of simplicity, the present invention will no longer exhaustively list the specific point values ​​included in the range;

[0065] For a 5L rotary evaporation container, 1 to 2L of ball-milled slurry or powder after secondary rinsing can be processed at one time. The rotary evaporation time for rotary evaporation solid-liquid separation of the ball-milled slurry or rotary evaporation solid-liquid separation of the powder after secondary rinsing is 3 to 4 hours. The rotary evaporation time for rotary evaporation solid-liquid separation of the ball-milled slurry or rotary evaporation solid-liquid separation of the powder after secondary rinsing is preferably 3 hours, 3.5 hours and 4 hours. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range;

[0066] The present invention also provides a pure ceramic powder, which is prepared according to any of the above-mentioned granulation waste powder separation and recovery methods.

[0067] Example 1

[0068] The present invention provides a method for separating and recovering granulation waste powder, comprising the following steps:

[0069] S1: Pour 1 kg of granulation waste powder into a ball mill, add 1 kg of isopropanol and 0.1 kg of citric acid, the concentration of the isopropanol is 90%;

[0070] Adding citric acid provides an acidic environment. In this acidic environment, the dispersant ammonium polyacrylate in the granulation waste powder can be fully decomposed into polyacrylic acid and NH4+;

[0071] S2 adds 2 kg of grinding balls, wherein the grinding balls are alumina balls, and performs ball milling for 30 min under vacuum conditions, wherein the vacuum degree of the ball milling under the vacuum conditions is 0.09 MPa, and the rotation speed of the ball milling under the vacuum conditions is 50 rpm. After ball milling, the mixture is allowed to stand for 30 min, and after standing, the mixture is fully decomposed using ammonium polyacrylate, and the following ball milling steps are repeated at least five times: the mixture is allowed to stand for 30 min under vacuum conditions, wherein the vacuum degree of the ball milling under the vacuum conditions is 0.09 MPa, and the rotation speed of the ball milling under the vacuum conditions is 50 rpm. After ball milling, the mixture is allowed to stand for 30 min, and after standing, the mixture is fully decomposed using ammonium polyacrylate, to obtain a ball-milled slurry;

[0072] During the ball milling process, the addition of citric acid provides an acidic environment, so that the organic additives in the granulation waste powder can be fully dissolved, and the ammonium polyacrylate is decomposed into polyacrylic acid and NH4+. NH4+ combines with water molecules and is removed in the form of NH3 under vacuum.

[0073] S3: the slurry after ball milling is subjected to rotary evaporation for solid-liquid separation. The rotary evaporation temperature for the rotary evaporation of the slurry after ball milling is 35°C and the rotary evaporation speed is 15 rpm to obtain a powder after rotary evaporation drying. For a 5L rotary evaporation container, 1L of the slurry after ball milling can be processed at one time. The rotary evaporation time for the rotary evaporation of the slurry after ball milling is 3h.

[0074] S4: The powder after rotary evaporation drying is rinsed twice in isopropanol. The rotary evaporation temperature of the powder after rotary evaporation drying in isopropanol is 35°C and the rotary evaporation speed is 15rpm. The powder after the secondary rinsing is subjected to rotary evaporation solid-liquid separation to prepare pure ceramic powder. For a 5L rotary evaporation container, 1L of the powder after the secondary rinsing can be processed at one time. The rotary evaporation time for the solid-liquid separation of the powder after the secondary rinsing is 3h.

[0075] The present invention also provides a pure ceramic powder, which is prepared according to any of the above-mentioned granulation waste powder separation and recovery methods.

[0076] Example 2

[0077] The present invention provides a method for separating and recovering granulation waste powder, comprising the following steps:

[0078] S1: Pour 1 kg of granulation waste powder into a ball mill, add 2 kg of ethanol and 0.15 kg of citric acid, and the concentration of the ethanol is preferably 85%;

[0079] S2 adds 3kg grinding balls, the grinding balls are zirconia balls, and performs ball milling for 35 minutes under vacuum conditions. The rotation speed of the ball milling under vacuum conditions is 45rpm, and the vacuum degree of the ball milling under vacuum conditions is 0.095MPa. After ball milling, it is placed for 60 minutes, and after being placed, it is fully decomposed with ammonium polyacrylate, and the following ball milling steps are repeated for at least five times: ball milling for 35 minutes under vacuum conditions, the rotation speed of the ball milling under vacuum conditions is 45rpm, and the vacuum degree of the ball milling under vacuum conditions is 0.095MPa. After ball milling, it is placed for 60 minutes, and after being placed, it is fully decomposed with ammonium polyacrylate to obtain a ball-milled slurry;

[0080] During the ball milling process, the addition of citric acid provides an acidic environment, so that the organic additives in the granulation waste powder can be fully dissolved, and the ammonium polyacrylate is decomposed into polyacrylic acid and NH4+. NH4+ combines with water molecules and is removed in the form of NH3 under vacuum.

[0081] S3: the slurry after ball milling is subjected to rotary evaporation for solid-liquid separation. The temperature for rotary evaporation for solid-liquid separation of the slurry after ball milling is 45° C. The rotary evaporation speed for rotary evaporation for solid-liquid separation of the slurry after ball milling is 5 rpm. A powder after rotary evaporation drying is obtained. For a 5 L rotary evaporation container, 2 L of the slurry after ball milling can be processed at one time. The rotary evaporation time for rotary evaporation for solid-liquid separation of the slurry after ball milling is 4 h.

[0082] S4: The powder after rotary evaporation drying is rinsed twice in isopropanol, and the powder after the second rinse is subjected to rotary evaporation for solid-liquid separation. The temperature for rotary evaporation of the powder after the second rinse is 45°C, and the rotary evaporation speed for rotary evaporation of the powder after the second rinse is 5rpm, to obtain pure ceramic powder. For a 5L rotary evaporation container, 2L of the second rinsed powder can be processed at one time, and the rotary evaporation time for rotary evaporation of the powder after the second rinse is 4h;

[0083] The present invention also provides a pure ceramic powder, which is prepared according to any of the above-mentioned granulation waste powder separation and recovery methods.

[0084] Example 3

[0085] The present invention provides a method for separating and recovering granulation waste powder, comprising the following steps:

[0086] S1: 1 kg of granulation waste powder is poured into a ball mill, and 1.5 kg of a mixture of ethanol and isopropanol and 0.12 kg of citric acid are added, wherein the concentration of the mixture of ethanol and isopropanol is 95%, and the mass ratio of ethanol to isopropanol in the mixture of ethanol and isopropanol is 1:1;

[0087] S2 adds 2.5 kg of grinding balls, wherein the grinding balls are a mixture of alumina balls and zirconia balls, wherein the mass ratio of alumina balls to zirconia balls in the mixture is 1:1, and ball milling is performed for 30 min under vacuum conditions, wherein the vacuum degree of the ball milling under the vacuum conditions is 0.092 MPa, and the rotation speed of the ball milling under the vacuum conditions is 50 rpm. After ball milling, the mixture is allowed to stand for 50 min, and after standing, the mixture is fully decomposed using ammonium polyacrylate, and the following ball milling steps are repeated for at least five times: ball milling is performed for 30 min under vacuum conditions, wherein the vacuum degree of the ball milling under the vacuum conditions is 0.092 MPa, and the rotation speed of the ball milling under the vacuum conditions is 50 rpm. After ball milling, the mixture is allowed to stand for 50 min, and after standing, the mixture is fully decomposed using ammonium polyacrylate, to obtain a ball-milled slurry;

[0088] During the ball milling process, the addition of citric acid provides an acidic environment, so that the organic additives in the granulation waste powder can be fully dissolved, and the ammonium polyacrylate is decomposed into polyacrylic acid and NH4+. NH4+ combines with water molecules and is removed in the form of NH3 under vacuum.

[0089] S3: the slurry after ball milling is subjected to rotary evaporation for solid-liquid separation, the rotary evaporation temperature for the rotary evaporation of the slurry after ball milling is 40°C, the rotary evaporation speed for the rotary evaporation of the slurry after ball milling is 10 rpm, and a powder after rotary evaporation drying is obtained. For a 5L rotary evaporation container, 1.5L of the slurry after ball milling can be processed at one time, and the rotary evaporation time for the rotary evaporation of the slurry after ball milling is 3.5h;

[0090] S4: The powder after rotary evaporation drying is rinsed twice in isopropanol, and the powder after the second rinse is subjected to rotary evaporation for solid-liquid separation. The rotary evaporation temperature for the second rinse is 40°C, and the rotary evaporation speed for the second rinse is 10 rpm to obtain pure ceramic powder. For a 5L rotary evaporation container, 1.5L of the second rinsed powder can be processed at one time, and the rotary evaporation time for the second rinsed powder is 3.5h.

[0091] The present invention also provides a pure ceramic powder, which is prepared according to any of the above-mentioned granulation waste powder separation and recovery methods.

[0092] Comparative Example 1

[0093] Comparative Example 1 provides a method for separating and recovering granulation waste powder, comprising the following steps:

[0094] S1 takes 1 kg of granulation waste powder and pours it into the ball mill, and adds 1 kg of isopropanol, the concentration of which is 90%.

[0095] S2 adds 2 kg of grinding balls, wherein the grinding balls are alumina balls, and performs ball milling for 30 min under vacuum conditions, wherein the vacuum degree of the ball milling under the vacuum conditions is 0.09 MPa, and the rotation speed of the ball milling under the vacuum conditions is 50 rpm. After ball milling, the mixture is allowed to stand for 30 min, and the following ball milling steps are repeated at least five times: performing ball milling for 30 min under vacuum conditions, wherein the vacuum degree of the ball milling under the vacuum conditions is 0.09 MPa, and the rotation speed of the ball milling under the vacuum conditions is 50 rpm. After ball milling, the mixture is allowed to stand for 30 min, and after standing, ammonium polyacrylate is used to fully decompose the mixture to obtain a ball-milled slurry;

[0096] S3: The slurry after ball milling is subjected to rotary evaporation for solid-liquid separation, wherein the rotary evaporation temperature for the rotary evaporation of the slurry after ball milling is 35° C. and the rotary evaporation speed is 15 rpm to obtain a powder after rotary evaporation drying;

[0097] S4 directly places the powder after rotary evaporation drying in a thermal degassing furnace for thermal degassing for 24 hours to obtain a thermally dehydrated powder.

[0098] Comparative Example 2

[0099] Comparative Example 2 provides a method for separating and recovering granulation waste powder, comprising the following steps:

[0100] S1 takes 1 kg of granulation waste powder and pours it into the ball mill, and adds 1 kg of isopropanol, the concentration of which is 90%.

[0101] S2 adds 2 kg of grinding balls, wherein the grinding balls are alumina balls, and performs ball milling for 30 min under vacuum conditions, wherein the vacuum degree of the ball milling under the vacuum conditions is 0.09 MPa, and the rotation speed of the ball milling under the vacuum conditions is 50 rpm. After ball milling, the mixture is allowed to stand for 30 min, and the following ball milling steps are repeated at least five times: performing ball milling for 30 min under vacuum conditions, wherein the vacuum degree of the ball milling under the vacuum conditions is 0.09 MPa, and the rotation speed of the ball milling under the vacuum conditions is 50 rpm. After ball milling, the mixture is allowed to stand for 30 min, and after standing, ammonium polyacrylate is used to fully decompose the mixture to obtain a ball-milled slurry;

[0102] S3: The slurry after ball milling is subjected to rotary evaporation for solid-liquid separation, wherein the rotary evaporation temperature for the rotary evaporation of the slurry after ball milling is 35° C. and the rotary evaporation speed is 15 rpm to obtain a powder after rotary evaporation drying;

[0103] S4: directly placing the powder after rotary evaporation drying in a thermal degassing furnace for thermal degassing for 24 hours to obtain a thermally dehydrated powder;

[0104] S5 sintering the heat-desorbed powder, the sintering process is heating to 1500°C, the heating rate is 10°C / min, the heat preservation time is 3h, the cooling rate is 10°C / min, and the sintered powder is obtained;

[0105] In step S5, the powder after thermal stripping is subjected to high-temperature sintering, which may cause the following technical problems: high-temperature sintering requires higher-performance sintering equipment, such as a high-temperature furnace and a temperature control system, which increases equipment costs and operating energy consumption.

[0106] Comparative Example 3

[0107] Comparative Example 3 provides a method for separating and recovering granulation waste powder, comprising the following steps:

[0108] S1 takes 1 kg of granulation waste powder and pours it into a ball mill, adds 1 kg of isopropanol and 0.1 kg of citric acid, wherein the alcohol substance is isopropanol, and the concentration of the isopropanol is 90%.

[0109] S2 adds 2 kg of grinding balls, wherein the grinding balls are alumina balls, and performs ball milling for 30 min under vacuum conditions, wherein the vacuum degree of the ball milling under the vacuum conditions is 0.09 MPa, and the rotation speed of the ball milling under the vacuum conditions is 50 rpm. After ball milling, the mixture is allowed to stand for 30 min, and after standing, the mixture is fully decomposed using ammonium polyacrylate, and the following ball milling steps are repeated at least five times: the mixture is allowed to stand for 30 min under vacuum conditions, wherein the vacuum degree of the ball milling under the vacuum conditions is 0.09 MPa, and the rotation speed of the ball milling under the vacuum conditions is 50 rpm. After ball milling, the mixture is allowed to stand for 30 min, and after standing, the mixture is fully decomposed using ammonium polyacrylate, to obtain a ball-milled slurry;

[0110] During the ball milling process, the addition of citric acid provides an acidic environment, so that the organic additives in the granulation waste powder can be fully dissolved, and the ammonium polyacrylate is decomposed into polyacrylic acid and NH4+. NH4+ combines with water molecules and is removed in the form of NH3 under vacuum.

[0111] S3: Place the ball-milled slurry in an open beaker (2000 ml beaker), set the water bath temperature to 45°C, evaporate to dryness for more than 8 hours, and at least 12 hours are required to obtain a rotary dried powder.

[0112] In order to solve the problem of recycling granulation waste powder, during the evaporation process of the ball-milled slurry, step S3 in comparative example 3 adopts the method of placing the ball-milled slurry in a container and letting it stand in a water bath for evaporation, which has the following technical problems: first, the evaporation efficiency is slow; second, alcohols are difficult to be effectively recycled, causing pollution to the environment.

[0113] In order to solve the problem of recycling waste powder from granulation, the slurry after ball milling is evaporated to dryness. In step 3 of Example 1 of the present application, the slurry after ball milling is subjected to rotary evaporation for solid-liquid separation. The rotary evaporation for solid-liquid separation can make the slurry fully roll and the solvent fully evaporate in the rotary evaporation drying equipment, thereby improving the efficiency of the rotary evaporation for solid-liquid separation. In addition, the alcohol solvent is condensed and recovered through the cold water circulation of the rotary evaporation drying equipment, thereby reducing pollution to the environment.

[0114] Experimental means of experimental data testing

[0115] The powders prepared in Example 1 and Comparative Examples 1-2 were tested by EDS-semi-quantitative method, wherein the powders prepared in Example 1 were tested by EDS-semi-quantitative method with the following parameters:

[0116] Signal: SED (Secondary Electron Detector);

[0117] Accelerating voltage: 20.0 kv;

[0118] Working distance: 19.4mm;

[0119] Magnification: ×1,700;

[0120] Vacuum mode: High vacuum.

[0121] The powder prepared in Comparative Example 1 was tested by EDS-semi-quantitative method with the following parameters:

[0122] Signal: SED (Secondary Electron Detector);

[0123] Accelerating voltage: 20.0 kv;

[0124] Working distance: 19.4mm;

[0125] Magnification: ×500;

[0126] Vacuum mode: High vacuum.

[0127] The powder prepared in Comparative Example 2 was tested by EDS-semi-quantitative method with the following parameters:

[0128] Signal: SED (Secondary Electron Detector);

[0129] Accelerating voltage: 20.0 kv;

[0130] Working distance: 15.5mm;

[0131] Magnification: ×190;

[0132] Vacuum mode: High vacuum.

[0133] The elemental analysis experimental data of the powders prepared in Example 1 and Comparative Examples 1-2 were tested by EDS-semi-quantitative method and are shown in Tables 1-3 below.

[0134] Table 1 Elemental analysis experimental data of the powder prepared in Example 1 tested by EDS-semi-quantitative method

[0135]

[0136] Table 2 Elemental analysis experimental data of the powder prepared in Comparative Example 1 tested by EDS-semi-quantitative method

[0137]

[0138] Table 3 Elemental analysis experimental data of the powder prepared in Comparative Example 2 tested by EDS-semi-quantitative method

[0139]

[0140] From Table 1-3 and Figure 1-3As shown, the powders prepared in Example 1 and Comparative Examples 1-2 were tested by EDS-semi-quantitative method for elemental analysis experimental data. We can observe that the carbon content percentage of the powder prepared in Comparative Example 1 is as high as more than 30%, and N element appears in the powder, proving that the powder prepared in Comparative Example 1 contains a large amount of organic matter. The carbon content percentages of the powders prepared in Example 1 of the present application and the powders prepared by high-temperature sintering in Comparative Example 2 are similar. The carbon content percentage in the powders prepared by high-temperature sintering in Comparative Example 2 drops to less than 9.1%, and the powder does not contain N element. It can be judged that the powder does not contain organic matter, and a pure ceramic powder is obtained. However, in the process of preparing the powder by high-temperature sintering in Comparative Example 2, the following technical problems will arise: high-temperature sintering requires higher-performance sintering equipment, such as a high-temperature furnace and a temperature control system, which increases equipment costs and operating energy consumption; the carbon content percentage in the powder prepared in Example 1 of the present application drops to below 8.9%, and the powder does not contain N element. It can be judged that the powder does not contain organic matter, and a purer ceramic powder is obtained. In addition, the preparation process does not require high-temperature sintering, which reduces equipment costs and operating energy consumption.

[0141] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all various changes or equivalent substitutions falling within the scope of the claims of the present application are included. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application are within the scope protected by the present invention.

Claims

1. A method for separating and recovering granulation waste powder, characterized in that: The following steps are involved: S1 takes an appropriate amount of granulation waste powder and pours it into a ball mill, and adds alcohol and citric acid; S2 adds grinding balls, performs ball milling under vacuum conditions, leaves the milling aside, and uses ammonium polyacrylate to fully decompose the milling after leaving aside, and then repeats the following ball milling steps at least five times: performs ball milling under vacuum conditions, leaves the milling aside, and uses ammonium polyacrylate to fully decompose the milling after leaving aside, to obtain a ball milled slurry; S3: The slurry after ball milling is subjected to rotary evaporation for solid-liquid separation to obtain a rotary dried powder; S4: The powder after rotary evaporation drying is rinsed twice in isopropanol to obtain a powder after secondary rinsing, and the powder after secondary rinsing is subjected to rotary evaporation for solid-liquid separation to obtain pure ceramic powder.

2. The method for separating and recovering granulation waste powder according to claim 1, characterized in that: The concentration of the alcohol substance is 85% to 95%, and the alcohol substance includes: any one or two of ethanol and isopropanol.

3. The method for separating and recovering granulation waste powder according to claim 1 or 2, characterized in that: The mass ratio of the granulation waste powder to the alcohol substance is 1:(1-2).

4. The method for separating and recovering granulation waste powder according to claim 1, characterized in that: The mass ratio of the granulation waste powder to the citric acid is 1:(0.1-0.15).

5. The method for separating and recovering granulation waste powder according to claim 1, characterized in that: The grinding balls are either one or both of aluminum oxide balls and zirconium oxide balls, and the mass ratio of the granulation waste powder to the grinding balls is 1:(2-3).

6. The method for separating and recovering granulation waste powder according to claim 1 or 5, characterized in that: In step S2, the vacuum degree of the ball milling under the vacuum condition is 0.09 MPa to 0.095 MPa, the time of the ball milling under the vacuum condition is 25 min to 35 min, the rotation speed of the ball milling under the vacuum condition is 45 rpm to 55 rpm, and the standing time after the ball milling is 30 min to 60 min.

7. The method for separating and recovering granulation waste powder according to claim 1, characterized in that: In step S2, during the ball milling process, the addition of citric acid to provide an acidic environment allows the organic additives in the granulation waste powder to be fully dissolved, and the ammonium polyacrylate is decomposed into polyacrylic acid and NH4 + , NH4 + It combines with water molecules and is removed in the form of NH3 under vacuum.

8. The method for separating and recovering granulation waste powder according to claim 1, characterized in that: The rotary evaporation temperature for rotary evaporation solid-liquid separation of the ball-milled slurry or secondary rinsing of the powder after rotary evaporation drying in isopropanol is 35°C to 45°C, and the rotary evaporation speed for rotary evaporation solid-liquid separation of the ball-milled slurry or secondary rinsing of the powder after rotary evaporation drying in isopropanol is 5rpm to 15rpm.

9. A pure ceramic powder, characterized in that: The granulation waste powder is prepared according to any one of claims 1 to 8.

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