CN112678779A - Preparation method of ammonium persulfate crystal - Google Patents
Preparation method of ammonium persulfate crystal Download PDFInfo
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- CN112678779A CN112678779A CN202110142580.8A CN202110142580A CN112678779A CN 112678779 A CN112678779 A CN 112678779A CN 202110142580 A CN202110142580 A CN 202110142580A CN 112678779 A CN112678779 A CN 112678779A
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Abstract
The invention provides a preparation method of ammonium persulfate crystals, which comprises the following steps: adding ammonium persulfate seed crystal into the mixture liquid of ammonium persulfate and ammonium sulfate at 25-35 ℃ for seeding under the stirring action of a propelling stirrer with a guide cylinder, slowly heating to 0.5-1 ℃, and then cooling to-3-10 ℃ at the cooling rate of 3-18 ℃/h for cooling crystallization to obtain ammonium persulfate crystals; the average grain diameter of the ammonium persulfate crystals is more than 800 mu m; by using the push type stirrer with the guide cylinder, the micro-amplitude heating process at 0.5-1 ℃ is carried out, the cooling range is expanded, the growth and crystallization process of the crystal can be better controlled through the multi-factor synergistic cooperation effect, the increase of the crystal purity, the uniformity and the average granularity is facilitated, the anti-caking performance of the ammonium persulfate crystal can be improved, and the application range of the product is greatly expanded.
Description
Technical Field
The invention belongs to the field of industrial crystallization, relates to a preparation method of ammonium persulfate crystals, and particularly relates to a crystallization method of ammonium persulfate crystals with the purity higher than 99% and the average grain size higher than 800 mu m.
Background
Ammonium Persulfate, also known as Ammonium Persulfate or Ammonium Persulfate, also known as Ammonium Persulfate or Ammonium Persulfate, having the English name Ammonium Persulfate, or APS for short, has the molecular formula (NH4)2S2O8It is white monoclinic crystal or white powdery crystal, and is easy to dissolve in water. The dried ammonium persulfate has good stability and is easy to be moisture-blocking in humid air. After absorbing moisture, ammonium persulfate can generate hydrolysis reaction in an aqueous solution; can be oxidized and decomposed by heating or under the catalytic action of silver salt and other substances, and release a large amount of heat energy. Ammonium persulfate is widely applied to the fields of chemical industry, petroleum industry, electronic industry, food industry and the like, and is mainly used as an oxidant, a polymerization promoter for high-molecular polymerization, a polymerization agent for a vinyl chloride compound, an initiator for organic synthesis, an etching agent for the electronic industry, a desizing agent for the textile industry, an additive for a petroleum fracturing agent, an oxidant for aniline dye, a vulcanizing agent for rubber, a disinfectant for a swimming pool, a drying bleaching agent for a washing and dyeing shop, a hair bleaching agent and the like.
CN109665498A proposes a method for preparing ammonium persulfate crystals, which comprises the following specific operation steps: providing a mixed feed liquid of ammonium persulfate and ammonium sulfate, wherein the mass concentration ratio of the ammonium persulfate to the ammonium sulfate in the mixed feed liquid is 1: (2-3); when the temperature of the mixed feed liquid is controlled to be 20-25 ℃, adding ammonium persulfate seed crystals, and then cooling to-2-6 ℃ at a cooling rate of 5-15 ℃/h to obtain ammonium persulfate crystals, wherein the particle size of the ammonium persulfate crystals is more than 500 mu m; however, the average particle size and the anti-caking property of the ammonium persulfate crystals obtained by this method are still to be further improved.
Therefore, it is necessary to provide a method for producing ammonium persulfate crystals having a uniform particle size and an average particle size of more than 800 μm, in order to further increase the particle size of the ammonium persulfate crystals and reduce the agglomeration rate.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a preparation method of ammonium persulfate crystals with uniform particle size and average particle size higher than 800 microns, wherein a push type stirrer with a guide cylinder is used, a slow temperature rise process with a tiny amplitude of 0.5-1 ℃ is carried out, the temperature reduction range is expanded, the growth and crystallization process of the crystals can be better controlled through the synergistic cooperation of multiple factors, the increase of the purity, the uniformity and the average particle size of the crystals is facilitated, the anti-caking performance of the ammonium persulfate crystals can be improved, and the application range of the product is greatly expanded; and the preparation method is simple, the raw materials are easy to obtain, the price is low, the realization is easy, and the industrial large-scale production and application are convenient.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a preparation method of ammonium persulfate crystals, which comprises the following steps:
under the stirring action of a propeller stirrer with a guide cylinder, the mixture liquid of ammonium persulfate and ammonium sulfate is added with ammonium persulfate seed crystals at 25-35 ℃ (for example, 25 ℃, 26 ℃, 27 ℃, 28 ℃, 29 ℃, 30 ℃, 31 ℃, 32 ℃, 33 ℃, 34 ℃, 35 ℃ and the like) for seeding, then slowly heated to 0.5-1 ℃ (for example, 0.5 ℃, 0.6 ℃, 0.7 ℃, 0.8 ℃, 0.9 ℃, 1 ℃ and the like), and then cooled to-3-10 ℃ (for example, -3 ℃ and-10 ℃/h, 11 ℃/h, 12 ℃/h, 13 ℃/h, 14 ℃/h, 15 ℃/h, 16 ℃/h, 17 ℃/h, 18 ℃/h and the like) at a cooling rate of 3-18 ℃/h (for example, 3℃ and-10℃), 4 ℃ below zero, -5 ℃ below zero, -6 ℃ below zero, -7 ℃ below zero, -8 ℃ below zero, -9 ℃ below zero, -10 ℃ below zero, and the like) to obtain ammonium persulfate crystals.
The preparation method is simple, the raw materials are easy to obtain, the price is low, the realization is easy, and the large-scale industrial production and application are facilitated.
The ammonium persulfate crystal prepared by the preparation method has high purity and uniformity, and the average grain diameter of the crystal is larger than 800 mu m.
The invention adopts the push type stirrer with the guide cylinder, on one hand, the flow field can be strengthened, and the crystallization process is controlled not to generate secondary nucleation, thereby ensuring that only the crystal growth process is generated in the crystallization process, but not the nucleation phenomenon, and ensuring the continuous growth of solute on the surface of the crystal seed; on the other hand, the method can effectively prevent the seed crystals from settling, is convenient for improving the uniformity of crystal particles, and can ensure that the shearing force in the crystallizer is more stable and uniform.
After the seed crystal is added, the slow heating process with the tiny range of 0.5-1 ℃ is carried out under the stirring action of the propelling type stirrer with the guide cylinder, so that the fine crystals in the crystallization process can be eliminated, the growth of the precipitated solute on the surface of the fine crystals is avoided, and the uniformity and the average grain size of the crystals are increased.
According to the invention, by increasing the cooling range, more solutes can be separated out on the premise of ensuring the product purity; and by reducing the use of the seed crystal amount, the growth and crystallization process of the crystal can be better controlled, more solute can be ensured to grow on the surface of the seed crystal, and the average grain size of the crystal is improved.
The mixed feed liquid of ammonium persulfate and ammonium sulfate can be obtained by purchase or self-preparation.
In the present invention, the mass ratio of ammonium persulfate to ammonium sulfate in the mixed feed liquid of ammonium persulfate and ammonium sulfate is 1 (1-2), for example, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, etc., preferably 1 (1.1-1.4).
In the invention, the quality ratio of ammonium persulfate to ammonium sulfate in the mixed feed liquid is controlled so as to ensure that the purity and the average grain diameter of ammonium persulfate crystals meet the requirements at the same time; if the proportion of the ammonium persulfate is too high, secondary nucleation is initiated, so that the average grain size of ammonium persulfate crystals is reduced; if the proportion of ammonium sulfate is too high, the purity of ammonium persulfate crystals cannot reach 99%.
In the present invention, the concentration of ammonium persulfate in the mixed feed liquid is 0.35 to 0.5g/mL, for example, 0.35g/mL, 0.37g/mL, 0.4g/mL, 0.42g/mL, 0.45g/mL, 0.47g/mL, 0.5g/mL or the like, preferably 0.4 to 0.45 g/mL.
In the invention, the propelling type stirrer with the guide cylinder comprises a stirring driving device, a stirring paddle connected with the stirring driving device and the guide cylinder coaxially arranged with the stirring paddle.
In the present invention, the crystallization process of the ammonium persulfate crystals is performed in a crystallizer.
In the invention, the propulsion stirrer with the guide cylinder comprises a conventional propulsion stirrer and the guide cylinder sleeved on the outer surface of a stirring paddle of the propulsion stirrer; if the outer surface of the stirring paddle is not sleeved with the guide cylinder or does not adopt a push type stirrer, the uniformity of a final product can be influenced, and the increase of the grain size of crystals is not facilitated.
The invention does not limit the concrete structure and size of the guide shell, and only needs to meet the adaptability with the propelling type stirrer and the crystallizer, and the technical personnel in the field can adjust the guide shell according to the actual requirement; the invention does not limit the specific design and model of the crystallizer, and can be used in the basic crystallization process, and the technicians in the field can adjust the crystallizer according to the actual needs.
In the present invention, the stirring rate is 50 to 300rpm, for example, 50rpm, 80rpm, 100rpm, 120rpm, 150rpm, 180rpm, 200rpm, 220rpm, 250rpm, 280rpm, 300rpm and the like, preferably 230 and 260 rpm.
The stirring speed is controlled to be 50-300rpm, and the ammonium persulfate crystal can be prevented from settling while the ammonium persulfate crystal is not stirred; if the stirring speed is too high, crystals are small; if the stirring rate is too low, the crystals settle.
In the present invention, the ammonium persulfate seed crystal has an average particle diameter of 60 to 100 mesh, for example, 60 mesh, 70 mesh, 80 mesh, 90 mesh, 100 mesh, etc., preferably 80 to 100 mesh.
In the present invention, the ammonium persulfate seed crystal is added in an amount of 5 to 7mg, for example, 5mg, 5.2mg, 5.5mg, 5.7mg, 6mg, 6.2mg, 6.5mg, 6.7mg, 7mg, etc., preferably 5.5 to 6.5mg, based on 1mL of the mixed feed liquid.
In the invention, the amount of the added seed crystal is less, and the final ammonium persulfate crystal particle size is larger under the condition that the amount of the precipitated solute is the same.
In the present invention, the temperature at which the ammonium persulfate seed crystal is added is preferably 28 to 33 ℃ such as 28 ℃, 29 ℃, 30 ℃, 31 ℃, 32 ℃, 33 ℃ and the like.
In the invention, the rate of temperature rise is 0.5-1 ℃/h.
In the invention, the crystallization process is better controlled by controlling the temperature rise rate of the temperature rise process; when the temperature rise rate is too fast, the seed crystal is easy to dissolve, which is not beneficial to the crystallization process; when the temperature rise rate is too slow, although the final product is not greatly affected, the time of the process flow is increased, which is not favorable for the economy and efficiency of industrial production.
In the present invention, the cooling rate of the cooling crystal is preferably 5 to 10 ℃/h, for example, 5 ℃/h, 5.5 ℃/h, 6 ℃/h, 6.5 ℃/h, 7 ℃/h, 7.5 ℃/h, 8 ℃/h, 8.5 ℃/h, 9 ℃/h, 9.5 ℃/h, 10 ℃/h, and the like.
In the present invention, the temperature of the temperature-decreasing crystallization is preferably decreased to-4 to-8 ℃, for example, -4 ℃, -5 ℃, -6 ℃, -7 ℃, -8 ℃.
In the invention, the crystallization process is better controlled by controlling the cooling rate and the final temperature of the cooling crystallization; when the temperature reduction rate is too fast or the temperature reduction range is too narrow, the crystal growth time is not enough or the precipitated solute is too little, so that the particle size of the ammonium persulfate crystal is reduced; when the temperature reduction rate is too slow or the temperature reduction range is too wide, the time of the process flow is increased, which is not favorable for the economical efficiency and the efficiency of industrial production.
In the present invention, the purity of the ammonium persulfate crystal is higher than 99%, for example, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, etc.
In the present invention, the ammonium persulfate crystals have an average particle size of more than 800. mu.m, for example, 800. mu.m, 810. mu.m, 820. mu.m, 830. mu.m, 840. mu.m, 850. mu.m, 860. mu.m, 870. mu.m, 880. mu.m, 890. mu.m, 900. mu.m, 920. mu.m, 950. mu.m, 970. mu.m, 1000. mu.m, etc., preferably 800-900. mu.m.
In the invention, the preparation method comprises the following steps:
(1) placing the mixed feed liquid of ammonium persulfate and ammonium sulfate in a crystallizer, and stirring under the action of a propelling stirrer with a guide cylinder; wherein the mass ratio of ammonium persulfate to ammonium sulfate in the mixed feed liquid is 1:1-1:2, and the stirring speed is 200-300 rpm;
(2) under the condition of keeping the stirring in the step (1), adding ammonium persulfate seed crystals with the particle size of 60-100 meshes at 25-35 ℃ for seeding, and then slowly heating to 0.5-1 ℃; wherein the heating rate is 0.5-1 ℃/h;
(3) cooling the mixed material liquid heated in the step (2) to-3 to-10 ℃ at a cooling rate of 3-18 ℃/h for cooling crystallization, and then sequentially filtering, cleaning and drying to obtain ammonium persulfate crystals;
the purity of the obtained ammonium persulfate crystal is higher than 99 percent, and the average grain diameter is larger than 800 mu m.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, by using the push type stirrer with the guide cylinder, a small-amplitude slow heating process of 0.5-1 ℃ is carried out, the cooling range is expanded, the growth and crystallization processes of crystals can be better controlled through the synergistic cooperation of multiple factors, the purity, uniformity and average particle size of the crystals can be increased conveniently, the anti-caking performance of ammonium persulfate crystals can be improved, and the application range of products is greatly expanded; and the preparation method is simple, the raw materials are easy to obtain, the price is low, the realization is easy, and the industrial large-scale production and application are convenient.
Drawings
FIG. 1 is a schematic structural view of a crystallizer provided with a guide cylinder and a propeller-type stirring paddle;
FIG. 2 is a microscopic image of the product obtained in example 1;
FIG. 3 is a microscopic view of the product obtained with reference to comparative example 1;
FIG. 4 is a graph showing the particle size distribution of the products obtained in example 1 and comparative example 1;
FIG. 5 is an XRD pattern of the product obtained in example 1 and a commercial ammonium persulfate product.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
The embodiment provides a crystallization method of ammonium persulfate crystals, which comprises the following steps:
(1) dissolving ammonium persulfate and ammonium sulfate in distilled water according to the mass ratio of 1:1.25 to prepare mixed feed liquid, wherein the concentration of the ammonium persulfate is 0.4 g/mL;
(2) putting the mixed feed liquid obtained in the step (1) into a crystallizer with a guide cylinder, starting a push type stirrer, controlling the stirring speed to be 230rpm, adding ammonium persulfate seed crystals with the particle size of 80-100 meshes when the temperature of the mixed feed liquid is controlled to be 30 ℃, wherein the concentration of the seed crystals in the mixed feed liquid is 6mg/mL, slowly heating to 0.5 ℃, and then cooling to-5 ℃ at the cooling speed of 10 ℃/h for cooling crystallization to obtain a crystallization mixture;
(3) and (3) filtering the crystallization mixture obtained in the step (2) to obtain a solid, and then cleaning and drying to obtain ammonium persulfate crystals.
Fig. 1 is a schematic structural diagram of a crystallizer provided with a guide shell and a push-type stirring paddle, as can be seen from fig. 1, the guide shell and the push-type stirring paddle are arranged in the crystallizer, the push-type stirring paddle comprises a driving device and a stirring paddle connected with the driving device, one end of the stirring paddle, which is far away from the driving device, is inserted into the crystallizer, and one end of the guide shell, which is inserted into the crystallizer, is sleeved with the guide shell.
The purity of the ammonium persulfate crystals obtained in this example was measured by a gas chromatograph Bruker SCION 456-GC, and it was found that the purity of the ammonium persulfate crystals obtained was 99%.
The ammonium persulfate crystals obtained in this example were subjected to a particle size distribution test (the test instrument was a malvern MS3000 laser particle sizer), and it was found that the average particle size of the obtained ammonium persulfate crystals was 897 μm.
Reference comparative example 1
See CN 109665498A.
The ammonium persulfate crystals obtained in this comparative example were subjected to the same test method as in example 1, and the obtained ammonium persulfate crystals had a purity of 99% and an average particle diameter of 516 μm.
FIG. 2 is a microscopic view of the product obtained in example 1, with a scale of 1mm, FIG. 3 is a microscopic view of the product obtained in reference to comparative example 1, with a scale of 1mm, and it is apparent from a comparison of FIGS. 2 and 3 that the crystal size of ammonium persulfate obtained in example 1 is larger.
FIG. 4 is a graph showing a particle size distribution of the products obtained in example 1 and comparative example 1, and it can be seen from FIG. 4 that the ammonium persulfate crystals obtained in example 1 have a larger average particle size and a more uniform particle size.
FIG. 5 is an XRD pattern of the product obtained in example 1 and a commercial ammonium persulfate product (from Wien division of Hebei Ji Heng Co., Ltd.), and it can be understood from FIG. 5 that the XRD pattern of the ammonium persulfate crystal produced by the present invention is consistent with that of the commercial product.
The samples of example 1 and reference example 1 were placed in a caking mould under an applied pressure of 10300Pa and an added amount of water of 1% for 3 days to obtain A, B two sets of identical cylindrical caking samples, 5mm in diameter and 1cm in height, respectively. The agglomerated samples were allowed to free fall from the same height and the degree of crushing was compared, i.e. the agglomerated strength test, the test results are shown in table 1:
TABLE 1
| Experiment of | Sample (I) | Height of free fall | Rate of |
|
| 1 | Example 1 caking | 1m | 100％ | |
| 2 | Example 1 blocking | 2m | 100％ | |
| 3 | Reference comparative example 1 blocking | 1m | 20％ | |
| 4 | Reference comparative example 1 blocking sample B | 2m | 45％ |
As can be seen from Table 1, comparing the caking strength test experiment 1 and experiments 3 and 4, it can be seen that the caking sample prepared from the product of example 1 can be completely broken down already when free falling at a height of 1 m; whereas the agglomerated sample obtained from the product of comparative example 1 had a breakage rate of less than 50% when it was free-dropped at a height of 2 m. The experimental result shows that the anti-caking performance of the ammonium persulfate product prepared by the invention is far superior to that of the product in the patent CN 109665498A.
Example 2
The only difference from example 1 is that the concentration of ammonium sulfate was 0.8g/mL, and the preparation method was the same as example 1.
The ammonium persulfate crystals obtained in this example were subjected to the same test method as in example 1, and it was found that the purity of the obtained ammonium persulfate crystals was 98% and the average particle diameter was 822. mu.m.
Example 3
The only difference from example 1 is that the ammonium persulfate concentration was 0.5g/mL and the ammonium sulfate concentration was 0.625g/mL, and the other preparation methods were the same as example 1.
The ammonium persulfate crystals obtained in this example were subjected to the same test method as in example 1, and it was found that the purity of the obtained ammonium persulfate crystals was 99% and the average particle diameter was 831. mu.m.
Example 4
The only difference from example 1 is that the particle size of the ammonium persulfate seed crystal is 60-80 mesh, and the rest of the preparation method is the same as that of example 1.
The same test as in example 1 was conducted on the ammonium persulfate crystals obtained in this example, and it was found that the obtained ammonium persulfate crystals had a purity of 99% and an average particle diameter of 825 μm.
Example 5
The only difference from example 1 is that the concentration of ammonium persulfate seed crystals in the mixed feed solution was 7mg/mL, and the other preparation methods were the same as those of example 1.
The ammonium persulfate crystals obtained in this example were measured by the same test method as in example 1, and it was found that the purity of the obtained ammonium persulfate crystals was 99% and the average particle diameter was 809 μm.
Example 6
The only difference from example 1 is that the temperature at the time of adding ammonium persulfate seed crystal was 27 ℃ and the other preparation method was the same as example 1.
The ammonium persulfate crystals obtained in this example were measured by the same test method as in example 1, and it was found that the obtained ammonium persulfate crystals had a purity of 99% and an average particle diameter of 813 μm.
Example 7
The only difference from example 1 is that the cooling rate is 15 ℃/h and the rest of the preparation method is the same as example 1.
The ammonium persulfate crystals obtained in this example were measured by the same test method as in example 1, and it was found that the purity of the obtained ammonium persulfate crystals was 99% and the average particle diameter was 818 μm.
Example 8
The only difference from example 1 is that the end point of the temperature reduction is-3 ℃, and the rest of the preparation method is the same as example 1.
The ammonium persulfate crystals obtained in this example were subjected to the same test method as in example 1, and it was found that the purity of the obtained ammonium persulfate crystals was 99% and the average particle diameter was 837 μm.
Example 9
The only difference from example 1 is that the teaching rate is 300rpm, and the rest of the preparation method is the same as example 1.
The ammonium persulfate crystals obtained in this example were subjected to the same test method as in example 1, and it was found that the purity of the obtained ammonium persulfate crystals was 99% and the average particle diameter was 846. mu.m.
Example 10
(1) Dissolving ammonium persulfate and ammonium sulfate in distilled water according to the mass ratio of 1:1 to prepare mixed feed liquid, wherein the concentration of the ammonium persulfate is 0.5 g/mL;
(2) putting the mixed material liquid obtained in the step (1) into a crystallizer with a guide cylinder, starting a push type stirrer, controlling the stirring speed to be 230rpm, adding ammonium persulfate seed crystals with the particle size of 80-100 meshes when the temperature of the mixed material liquid is controlled to be 25 ℃, wherein the concentration of the seed crystals in the mixed material liquid is 6mg/mL, slowly heating to 0.5 ℃, and then cooling to-5 ℃ at the cooling speed of 15 ℃/h for cooling crystallization to obtain a crystallization mixture;
(3) and (3) filtering the crystallization mixture obtained in the step (2) to obtain a solid, and then cleaning and drying to obtain ammonium persulfate crystals.
The ammonium persulfate crystals obtained in this example had a purity of 99% and an average particle diameter of 811 μm.
Example 11
(1) Dissolving ammonium persulfate and ammonium sulfate in distilled water according to the mass ratio of 1:1.5 to prepare mixed feed liquid, wherein the concentration of the ammonium persulfate is 0.45 g/mL;
(2) putting the mixed feed liquid obtained in the step (1) into a crystallizer with a guide cylinder, starting a push type stirrer, controlling the stirring speed to be 260rpm, adding ammonium persulfate seed crystals with the particle size of 80-100 meshes when the temperature of the mixed feed liquid is controlled to be 30 ℃, wherein the concentration of the seed crystals in the mixed feed liquid is 6mg/mL, slowly heating to 1 ℃, and then cooling to-5 ℃ at the cooling rate of 10 ℃/h for cooling crystallization to obtain a crystallization mixture;
(3) and (3) filtering the crystallization mixture obtained in the step (2) to obtain a solid, and then cleaning and drying to obtain ammonium persulfate crystals.
The ammonium persulfate crystals obtained in this example had a purity of 99% and an average particle diameter of 819. mu.m.
Example 12
(1) Dissolving ammonium persulfate and ammonium sulfate in distilled water according to the mass ratio of 1:1.25 to prepare mixed feed liquid, wherein the concentration of the ammonium persulfate is 0.45 g/mL;
(2) placing the mixed feed liquid obtained in the step (1) in a crystallizer with a guide cylinder, starting a push type stirrer, controlling the stirring speed to be 300rpm, adding ammonium persulfate seed crystals with the particle size of 80-100 meshes when the temperature of the mixed feed liquid is controlled to be 27 ℃, wherein the concentration of the seed crystals in the mixed feed liquid is 7mg/mL, slowly heating to 1 ℃, and then cooling to-8 ℃ at the cooling speed of 10 ℃/h for cooling crystallization to obtain a crystallization mixture;
(3) and (3) filtering the crystallization mixture obtained in the step (2) to obtain a solid, and then cleaning and drying to obtain ammonium persulfate crystals.
The ammonium persulfate crystals obtained in this example had a purity of 99% and an average particle diameter of 802 μm.
Comparative example 1
The difference from the example 1 is that the propeller of the propeller stirrer is coaxially not sleeved with a draft tube, and the other preparation methods are the same as the example 1.
The ammonium persulfate crystals obtained in this comparative example were measured by the same test method as in example 1, and it was found that the obtained ammonium persulfate crystals had a purity of 99% and an average particle diameter of 641. mu.m.
As can be seen from comparison between example 1 and comparative example 1, the draft tube influences the crystal grain size by influencing the secondary nucleation, and the average grain size of ammonium persulfate crystals cannot reach 800 μm without the draft tube.
Comparative example 2
The only difference from example 1 is that the propeller stirrer was replaced with an anchor stirrer, and the rest of the preparation method was the same as example 1.
The ammonium persulfate crystals obtained in this comparative example were measured by the same test method as in example 1, and it was found that the obtained ammonium persulfate crystals had a purity of 99% and an average particle diameter of 622. mu.m.
As can be seen from the comparison between example 1 and comparative example 2, the flow field formed by the propeller type stirring paddle is more uniform, the crystals can be effectively prevented from settling, and the average particle size of the ammonium persulfate crystals cannot reach 800 μm when the anchor type stirring paddle is used.
Comparative example 3
The only difference from example 1 is that the cooling rate was 20 ℃/h and the rest of the preparation method was the same as example 1.
The ammonium persulfate crystals obtained in this comparative example were measured by the same test method as in example 1, and it was found that the obtained ammonium persulfate crystals had a purity of 99% and an average particle diameter of 577 μm.
As is clear from a comparison between example 1 and comparative example 3, when the temperature decreasing rate is too fast, the temperature decreasing time is too short, and the average particle diameter of ammonium persulfate crystals cannot reach 800. mu.m.
Comparative example 4
The only difference from example 1 is that the concentration of the seed crystal in the mixed feed solution was 8.5mg/mL, and the other preparation methods were the same as example 1.
The ammonium persulfate crystals obtained in this comparative example were measured by the same test method as in example 1, and it was found that the obtained ammonium persulfate crystals had a purity of 99% and an average particle diameter of 630 μm.
As is clear from a comparison of example 1 and comparative example 4, when the amount of seed crystals is too large, the average particle diameter of ammonium persulfate crystals decreases to less than 800. mu.m.
Comparative example 5
The difference from example 1 is only that the concentration of the seed crystal in the mixed feed solution is 4mg/mL, and the other preparation methods are the same as example 1.
The ammonium persulfate crystals obtained in this comparative example were measured by the same test method as in example 1, and it was found that the obtained ammonium persulfate crystals had a purity of 99% and an average particle diameter of 612. mu.m.
As is clear from the comparison of example 1 and comparative example 5, when the seed crystal is added too little, secondary nucleation occurs, resulting in a bimodal distribution of crystal particle sizes and a decrease in average particle size.
Comparative example 6
The only difference from example 1 is that the temperature raising process after the seed crystal addition is not included, and the rest of the preparation method is the same as example 1.
The ammonium persulfate crystals obtained in this comparative example were measured by the same test method as in example 1, and it was found that the obtained ammonium persulfate crystals had a purity of 99% and an average particle diameter of 693 μm.
As is apparent from a comparison between example 1 and comparative example 6, if the temperature raising process is not performed after the seed crystal is added, the precipitated solute grows on fine crystals, resulting in a decrease in the average particle diameter of less than 800. mu.m.
Comparative example 7
The only difference from example 1 is that the temperature rise rate during the temperature rise process is too fast, 5 ℃/h, and the rest of the preparation method is the same as example 1.
The ammonium persulfate crystals obtained in this comparative example were measured by the same test method as in example 1, and it was found that the obtained ammonium persulfate crystals had a purity of 99% and an average particle diameter of 586 μm.
As is clear from a comparison between example 1 and comparative example 7, when the temperature increase rate is too fast, part of the seed crystals are also dissolved, resulting in a decrease in the seed crystal concentration, secondary nucleation occurs, and the average particle diameter of the crystals decreases recently.
Comparative example 8
The only difference from example 1 is that the end temperature of the temperature reduction process is-20 ℃, and the rest of the composition and the preparation method are the same as example 1.
The ammonium persulfate crystals obtained in this comparative example were measured by the same test method as in example 1, and it was found that the purity of the obtained ammonium persulfate crystals was 85% and the average particle diameter was 987 μm.
As can be seen from a comparison between example 1 and comparative example 8, when the temperature lowering end point is too low, ammonium sulfate precipitates and the crystal particle size increases, but more ammonium sulfate is contained, resulting in a decrease in the purity of ammonium persulfate crystals; in addition, too low a temperature requires more cooling medium, and is economically inefficient.
Comparative example 9
The only difference from example 1 is that the end temperature of the temperature reduction process is 5 ℃, and the rest of the composition and the preparation method are the same as example 1.
The ammonium persulfate crystals obtained in this comparative example were measured by the same test method as in example 1, and it was found that the obtained ammonium persulfate crystals had a purity of 99% and an average particle diameter of 581 μm.
As can be seen from the comparison between example 1 and comparative example 9, when the temperature lowering end point is too high, the temperature lowering range is too short, and the amount of solute precipitated is too small, resulting in small crystal length of ammonium persulfate and average particle diameter of less than 800. mu.m.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (10)
1. A preparation method of ammonium persulfate crystals is characterized by comprising the following steps:
adding ammonium persulfate seed crystal into the mixture liquid of ammonium persulfate and ammonium sulfate at 25-35 ℃ for seeding under the stirring action of a propelling stirrer with a guide cylinder, slowly heating to 0.5-1 ℃, and then cooling to-3-10 ℃ at the cooling rate of 3-18 ℃/h for cooling crystallization to obtain ammonium persulfate crystals.
2. The preparation method according to claim 1, wherein the mass ratio of ammonium persulfate to ammonium sulfate in the mixed feed liquid of ammonium persulfate and ammonium sulfate is 1 (1-2), preferably 1 (1.1-1.4);
preferably, the concentration of ammonium persulfate in the mixed feed liquid is 0.35-0.5 g/mL;
preferably, the concentration of ammonium persulfate in the mixed feed liquid is 0.4-0.45 g/mL.
3. The preparation method of claim 1, wherein the propeller mixer with the guide shell comprises a mixing driving device, a mixing paddle connected with the mixing driving device, and a guide shell coaxially arranged with the mixing paddle;
preferably, the crystallization process of the ammonium persulfate crystals is carried out in a crystallizer.
4. The method according to claim 1, wherein the stirring rate is 50-300rpm, preferably 230-260 rpm.
5. The production method according to claim 1, wherein the ammonium persulfate seed crystal has an average particle diameter of 60 to 100 mesh, preferably 80 to 100 mesh;
preferably, the addition amount of the ammonium persulfate seed crystal is 5-7mg, preferably 5.5-6.5mg, based on the volume of the mixed feed liquid of 1 mL.
6. The method according to claim 1, wherein the temperature at which the ammonium persulfate seed crystal is added is 28-33 ℃.
7. The method of claim 1, wherein the slow temperature rise rate is 0.5-1 ℃/h.
8. The preparation method according to claim 1, wherein the preferred cooling rate of the cooling crystallization is 5-10 ℃/h;
preferably, the temperature of the temperature-reducing crystallization is reduced to-4 to-8 ℃.
9. The preparation method according to claim 1, wherein the purity of the ammonium persulfate crystals is more than 99%;
preferably, the ammonium persulfate crystals have an average particle size of greater than 800 μm, preferably 800-900 μm.
10. The method of claim 1, comprising the steps of:
(1) placing the mixed feed liquid of ammonium persulfate and ammonium sulfate in a crystallizer, and stirring under the action of a propelling stirrer with a guide cylinder; wherein the mass ratio of ammonium persulfate to ammonium sulfate in the mixed liquid is 1:1-1:2, and the stirring speed is 200-300 ppm;
(2) under the condition of keeping the stirring in the step (1), adding ammonium persulfate seed crystals with the particle size of 60-100 meshes at 25-35 ℃ for seeding, and then slowly heating to 0.5-1 ℃; wherein the heating rate is 0.5-1 ℃/h;
(3) cooling the mixed material liquid heated in the step (2) to-3 to-10 ℃ at a cooling rate of 3-18 ℃/h for cooling crystallization, and then sequentially filtering, cleaning and drying to obtain ammonium persulfate crystals;
the purity of the obtained ammonium persulfate crystal is more than 99 percent, and the average grain diameter is more than 800 mu m.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112608471A (en) * | 2020-12-12 | 2021-04-06 | 东北师范大学 | High-crystallization-quality polypyrrole conductive film and preparation method thereof |
| CN115385776A (en) * | 2022-08-08 | 2022-11-25 | 天津大学 | Erythritol crystal and preparation method and application thereof |
| CN115403013A (en) * | 2022-09-01 | 2022-11-29 | 福建铭麟科技有限公司 | Preparation method and preparation device of ammonium persulfate crystal |
| CN115520880A (en) * | 2021-06-25 | 2022-12-27 | 中国石油化工股份有限公司 | Preparation method, crystallizer and production device of homogenized large-particle ammonium sulfate |
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| CN205340185U (en) * | 2015-11-27 | 2016-06-29 | 天津大学 | Continuous crystallization equipment of multistage high vacuum insulation flash distillation |
| CN109665498A (en) * | 2019-02-14 | 2019-04-23 | 河北中科同创科技发展有限公司 | A kind of preparation method of ammonium persulfate crystalline solid |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN205340185U (en) * | 2015-11-27 | 2016-06-29 | 天津大学 | Continuous crystallization equipment of multistage high vacuum insulation flash distillation |
| CN109665498A (en) * | 2019-02-14 | 2019-04-23 | 河北中科同创科技发展有限公司 | A kind of preparation method of ammonium persulfate crystalline solid |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112608471A (en) * | 2020-12-12 | 2021-04-06 | 东北师范大学 | High-crystallization-quality polypyrrole conductive film and preparation method thereof |
| CN112608471B (en) * | 2020-12-12 | 2022-09-02 | 东北师范大学 | High-crystallization-quality polypyrrole conductive film and preparation method thereof |
| CN115520880A (en) * | 2021-06-25 | 2022-12-27 | 中国石油化工股份有限公司 | Preparation method, crystallizer and production device of homogenized large-particle ammonium sulfate |
| CN115520880B (en) * | 2021-06-25 | 2024-03-26 | 中国石油化工股份有限公司 | Preparation method, crystallizer and production device of uniform large-particle ammonium sulfate |
| CN115385776A (en) * | 2022-08-08 | 2022-11-25 | 天津大学 | Erythritol crystal and preparation method and application thereof |
| CN115385776B (en) * | 2022-08-08 | 2023-09-26 | 天津大学 | Erythritol crystal and preparation method and application thereof |
| CN115403013A (en) * | 2022-09-01 | 2022-11-29 | 福建铭麟科技有限公司 | Preparation method and preparation device of ammonium persulfate crystal |
| CN115403013B (en) * | 2022-09-01 | 2023-12-15 | 福建铭麟科技有限公司 | Preparation method and preparation device of ammonium persulfate crystals |
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