Large-particle funnel crystal salt and preparation method thereof

文档序号:561222 发布日期:2021-05-18 浏览:23次 中文

阅读说明:本技术 一种大颗粒漏斗晶盐及其制备方法 (Large-particle funnel crystal salt and preparation method thereof ) 是由 唐娜 卢敏 杜威 张蕾 王松博 程鹏高 项军 张建平 于 2021-01-06 设计创作,主要内容包括:本发明公开了一种大颗粒漏斗晶盐,其粒度为0.1-1.0cm,该漏斗晶盐解决了盐的粒径细小、形貌单一、流动性差、易结块等问题。本发明还公开了漏斗晶盐的制备方法,制备过程中本发明针对性的加入20%的甲酰胺和2%的二甲基甲酰胺(基于氯化钠饱和溶液中溶质氯化钠的质量百分比),在蒸发温度为60℃,搅拌速率为100r/min,蒸发时间为6h的条件下,成功制备了粒度为0.6cm的大颗粒漏斗晶盐。本发明克服了现有技术中,为了提高产品盐的流动性,降低结块能力,就要提高其球形度制备球形盐的技术偏见,首次制备出漏斗状的大颗粒漏斗晶盐吗,且漏斗晶盐粒径分布均匀,外观良好,可与其他物质结合,增加盐的附加值。同时,本发明制备的漏斗晶盐流动性好、不易结块,易于存储。(The invention discloses large-particle funnel crystal salt, the particle size of which is 0.1-1.0cm, and the funnel crystal salt solves the problems of small particle size, single appearance, poor fluidity, easy caking and the like of salt. The invention also discloses a preparation method of the funnel crystal salt, wherein in the preparation process, 20% of formamide and 2% of dimethylformamide (based on the mass percentage of solute sodium chloride in a sodium chloride saturated solution) are added in a targeted manner, and under the conditions that the evaporation temperature is 60 ℃, the stirring speed is 100r/min, and the evaporation time is 6 hours, the large-particle funnel crystal salt with the particle size of 0.6cm is successfully prepared. The invention overcomes the technical prejudice that the sphericity of the product salt needs to be improved to prepare the spherical salt in order to improve the fluidity of the product salt and reduce the caking capacity in the prior art, and prepares the funnel-shaped large-particle funnel crystal salt for the first time, and the funnel crystal salt has uniform particle size distribution and good appearance, can be combined with other substances and increases the additional value of the salt. Meanwhile, the funnel crystal salt prepared by the invention has good fluidity, is not easy to agglomerate and is easy to store.)

1. The large-particle funnel crystal salt is characterized in that the particle size of the large-particle funnel crystal salt is 0.1-1.0cm, the large-particle funnel crystal salt is obtained by evaporating a sodium chloride saturated solution, formamide and dimethylformamide are added into the sodium chloride saturated solution, and the addition amounts of the formamide and the dimethylformamide are 10-50% and 1-5% of the solute mass of the sodium chloride saturated solution respectively.

2. The large-particle funnel crystalline salt of claim 1, wherein the amount of formamide and dimethylformamide added is 10: 1.

3. the large granular funnel crystalline salt of claim 1, wherein the particle size of the large granular funnel crystalline salt is 0.6cm, the large granular funnel crystalline salt is obtained by evaporating a saturated sodium chloride solution to which formamide and dimethylformamide are added, and the amount of the formamide and the dimethylformamide added is 20% and 2% of the solute mass of the saturated sodium chloride solution, respectively.

4. The method for preparing large-particle funnel crystalline salt according to claim 1, comprising the steps of:

(1) preparing a sodium chloride saturated solution in a crystallizer, adding an additive, heating, stirring and evaporating to separate out crystals; the additive is formamide and dimethylformamide;

(2) and (3) carrying out suction filtration and collection on the crystals obtained in the step (1), and drying the crystals to obtain the large-particle funnel crystal salt.

5. The preparation method according to claim 4, wherein the mass of the formamide and the dimethylformamide added in the step (1) is 1-50% and 1-5% of the mass of the solute of the saturated solution of the sodium chloride respectively, and in the heating, stirring and evaporation processes, the heating temperature is 45-75 ℃, the stirring speed is 50-200r/min, and the evaporation time is 2-10 h.

6. The preparation method according to claim 4, wherein the mass of the formamide and the dimethylformamide added in the step (1) is 20% and 2% of the mass of the solute of the saturated solution of the sodium chloride respectively, and in the heating, stirring and evaporation process, the heating temperature is 60 ℃, the stirring speed is 100r/min, and the evaporation time is 6 h.

7. The method according to claim 5, wherein the crystal induction period in the step (1) is 16 to 47 min.

8. The method according to claim 4, wherein the saturated sodium chloride solution is prepared at 45 to 75 ℃ in the step (1).

9. The method according to claim 4, wherein the drying temperature in the step (2) is 60 ℃ and the drying time is 2 hours.

Technical Field

The invention relates to the technical field of salt science and crystallization, in particular to large-particle funnel crystal salt and a preparation method thereof.

Background

Sodium chloride has wide application, is a very important chemical raw material, and the consumption of the sodium chloride is one of important marks for measuring the national industrialization degree. With the continuous progress of society, the application field of sodium chloride is continuously widened, and the quality requirement of people on sodium chloride is higher and higher. However, sodium chloride crystals are extremely easy to agglomerate, which is always a problem to be solved, and is especially obvious in damp and hot seasons, long-term storage and lump extrusion. The caking destroys the free flowing state of the product, and the product is often crushed during use, which brings great inconvenience to people. And the common sodium chloride has low price and low added value.

In order to prevent sodium chloride crystals from caking, mechanical methods, physical methods and additive methods are available at present, wherein the mechanical methods are based on a salt consolidation mechanism, air is pressed into a salt accumulation layer at certain intervals, and when weak bonding generated by just-bonded point crosslinking is not firm in the moisture absorption and release processes of salt crystalline particles while the salt crystalline particles are wet, the relative positions of the salt particles are changed by vibration of air pressing, so that the salt particles are broken to form firm crosslinking bonding, and the aim of preventing salt consolidation is fulfilled. The method has the defects of harsh storage conditions, high power consumption, limited storage capacity and the like. Therefore, this method is not basically adopted at home and abroad. The physical method is used to prevent the consolidation of salt, which is mainly controlled by the conditions of the environment humidity, temperature, pressure, etc. for storing salt. However, these conditions are less controllable and the anti-caking effect is oneAnd (4) the steps are as follows. Most of the methods widely used in industrial production in many countries adopt additive method, the additives selected abroad are mainly ammonium ferric citrate, ferrous phosphate and so on, while K is mainly selected in China at present4[Fe(CN)6]As an additive to prevent salt consolidation. K4[Fe(CN)6]Also called as potassium ferrocyanide, is a lemon yellow crystal or powder, which is dissolved in water and acetic acid, and is insoluble in alcohol, and when heated to 60 ℃, the crystal water is lost, and the high-temperature decomposition is toxic. Therefore, in the production process of table salt, a certain amount of K is added4[Fe(CN)6]To prevent caking, and not to be excessive, and must be uniform during the addition process. After observation and testing in long-term production practice, it has been found that proper uniformity is not easily achieved by the additive method regardless of the point of addition or the manner of addition, since the additive solution can only be sprayed onto the surface layer of the salt, whereas the salt in the middle and lower parts cannot be sprayed. Therefore, this method cannot be used for the production of sodium chloride for a long time.

In order to make the contact area of sodium chloride crystals smaller, the flowability better and the caking resistance less, some researchers at home and abroad are beginning to make an effort to change the cubic crystal form of sodium chloride by adding additives and controlling thermodynamic factors during the crystallization of sodium chloride. Currently, some researchers have added glycine as an additive to saturated sodium chloride solutions to obtain octahedral salts that resemble spheres and enhance the mobility of the crystals to some extent. However, the contact area of octahedral salts is still large and the anti-caking properties of the corresponding salts are not optimal. Other researchers have controlled the rate of stirring, fraction of vaporization and evaporation intensity to obtain spheroidal salts with large particles, but the sphericity is not high and the fluidity and anti-caking properties of the salt are not optimal. Further, researchers have controlled the solvent to be a mixed solution of methanol and water to dissolve sodium chloride into spherulites in the mixed solution, but the size of crystals dissolved into spherulites is small, about 150 μm, which causes the crystals to easily aggregate and thus agglomerate.

In summary, in order to improve the fluidity and the anti-caking performance of the product salt, in the current research, regardless of the addition of additives, the control of thermodynamic factors, or the control of stirring rate, vaporization fraction and evaporation strength, the cubic crystal form of sodium chloride can only be changed within a small range, that is, only the regulation and control can be performed between the cubic shape or the spherical shape, although the spherical shape of the spherical salt enhances the fluidity of the crystal to a certain extent, the sphericity of the spherical salt of the current product is not very high, the contact area between the spherical salts is still large, and the anti-caking performance of the corresponding salt is not particularly good.

Therefore, it is desirable to prepare polymorphic sodium chloride with small contact area and large particle size, which deviates from the current spherical salt limitation.

The present invention has been made to solve the above problems.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a large-particle funnel crystal salt and a preparation method thereof. The large-particle funnel crystal salt prepared by the invention has the following remarkable advantages: firstly, the crystal fluidity is good, and the salt is not easy to agglomerate. And secondly, the large-particle ball funnel crystal salt has good appearance and can be combined with other substances, so that the additional value of the salt is increased. Meanwhile, the invention provides the preparation method of the large-particle funnel crystal salt, which has the advantages of wide application range, simple salt preparation method and strong controllability.

The invention provides a large-particle funnel crystal salt, wherein the particle size of the large-particle funnel crystal salt is 0.1-1.0cm, the large-particle funnel crystal salt is obtained by evaporating a sodium chloride saturated solution, formamide and dimethylformamide are added into the sodium chloride saturated solution, and the addition amounts of the formamide and the dimethylformamide are respectively 1-50% and 1-5% of the solute mass of the sodium chloride saturated solution.

Wherein the addition amount of the formamide and the dimethylformamide is 10: 1.

the granularity of large granule funnel crystalline salt is 0.6cm, large granule funnel crystalline salt is evaporated by sodium chloride saturated solution and is obtained, formamide and dimethylformamide have been added to sodium chloride saturated solution, the addition of formamide and dimethylformamide is respectively sodium chloride saturated solution solute mass's 20% and 2%.

The second aspect of the present invention provides a preparation method of the large-particle funnel crystal salt, which comprises the following steps:

(1) preparing a sodium chloride saturated solution in a crystallizer, adding an additive, heating, stirring and evaporating to separate out crystals; the additive is formamide and dimethylformamide;

(2) and (3) carrying out suction filtration and collection on the crystals obtained in the step (1), and drying the crystals to obtain the large-particle funnel crystal salt.

Preferably, the mass of the formamide and the dimethylformamide added in the step (1) is 1-50% and 1-5% of the mass of the solute of the sodium chloride saturated solution respectively, in the heating, stirring and evaporation process, the heating temperature is 45-75 ℃, the stirring speed is 50-200r/min, and the evaporation time is 2-10 h.

Preferably, the mass of the formamide and the dimethylformamide added in the step (1) is 20 percent and 2 percent of the mass of the solute of the saturated solution of the sodium chloride respectively, and in the heating, stirring and evaporating process, the heating temperature is 60 ℃, the stirring speed is 100r/min, and the evaporating time is 6 h.

Preferably, the crystal induction period in step (1) is 16-47min at an evaporation temperature of 45-75 ℃. The crystal induction period is mainly related to the evaporation temperature, the crystal induction period is short, the crystal nucleation is facilitated, and the evaporation time is calculated from the time when the crystal begins to generate crystal nucleus to the time when the evaporation crystallization process is finished.

Preferably, a saturated sodium chloride solution is prepared at 45-75 ℃. About 37-38g of sodium chloride was dissolved in 100mL of distilled water. Wherein the temperature for preparing the saturated sodium chloride solution is kept consistent with the evaporation temperature in the subsequent heating, stirring and evaporation process.

Preferably, the drying temperature in the step (2) is 60 ℃, and the drying time is 2 h.

The large-particle funnel crystal salt provided by the invention has the advantages of wide application range, simple salt preparation method and strong controllability.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, 1-50% and 1-5% of formamide and dimethylformamide (based on the mass percentage of solute sodium chloride in a sodium chloride saturated solution) are added in a targeted manner in the process of evaporating, crystallizing and salifying sodium chloride to obtain the large-particle funnel crystal salt with the particle size of 0.1-1.0 cm.

2. In a preferred embodiment of the invention, the preparation process of the large-particle funnel crystal salt is further optimized by the invention as follows: adding formamide and dimethylformamide with the mass respectively being 20% and 2% of the solute mass of the saturated solution of sodium chloride, heating at 60 deg.C under stirring at 100r/min for 6h in the heating, stirring and evaporating process, and successfully preparing large-particle funnel crystal salt with particle size of 0.6 cm. The mixture is placed at the ambient temperature of 23 ℃ and the ambient humidity of 15 percent, and no obvious agglomeration phenomenon is found after 30 days.

3. The large-particle funnel crystal salt prepared by the invention has uniform particle size distribution, and most of the salt is funnel crystal salt with smooth and funnel-shaped surface and the particle sizes are almost distributed at the same level when seen by naked eyes.

4. The large-particle funnel crystal salt provided by the invention has good appearance, can be combined with other substances, and increases the additional value of the salt.

5. The invention has wide application range, simple salt preparation method and strong controllability.

6. The invention overcomes the technical prejudice that the sphericity of the product salt needs to be improved to prepare the spherical salt in order to improve the fluidity of the product salt and reduce the caking capacity in the prior art, prepares the funnel-shaped large-particle funnel crystal salt for the first time, widens the crystal form variety of sodium chloride and provides a research basis for preparing the polycrystalline sodium chloride.

Drawings

FIG. 1 is an EMS map of the surface of comparative example 1 of particulate salt prepared in comparative example 1;

FIG. 2 is an EMS map of the surface of comparative example 2 of particulate salt prepared in comparative example 2;

FIG. 3 is an EMS map of the surface of the polyhedral salt sample 1 prepared in example 1;

FIG. 4 is a graph of the surface of large particle funnel crystalline salt sample 1 prepared in example 2;

FIG. 5 is a plot of the surface of a large funnel-shaped crystalline salt sample 2 prepared in example 3;

FIG. 6 is a plot of the surface of large particle funnel crystalline salt sample 3 prepared in example 4;

FIG. 7 is an EMS map of the surface of polyhedral salt sample 2 prepared in example 5;

FIG. 8 is a drawing of the surface of large particle funnel crystalline salt sample 4 prepared in example 6;

FIG. 9 is a drawing of the surface of large particle funnel crystalline salt sample 5 prepared in example 7;

FIG. 10 is a drawing of the surface of large particle funnel crystalline salt sample 6 prepared in example 8;

FIG. 11 is a drawing of the surface of large particle funnel crystalline salt sample 7 prepared in example 9;

FIG. 12 is an EMS map of the surface of a spherical salt sample prepared in example 10;

FIG. 13 is a drawing of the surface of large particle funnel crystalline salt sample 8 prepared in example 11;

FIG. 14 is a drawing of the surface of large particle funnel salt sample 9 prepared in example 12;

wherein the magnification factors of figures 1-3, 7 and 10 are all 40, and the other figures are all camera shooting without magnification factors.

Detailed Description

The present invention will be described below with reference to specific examples, but the embodiments of the present invention are not limited thereto.

The morphology of the macroaggregated funnel crystalline salt was observed under a polarization microscope (EMS) and under the naked eye in the following comparative examples and examples, and the particle size was measured using a particle size analyzer and ruler measurement, respectively.

Comparative example 1

Preparing 300mL of saturated sodium chloride solution, placing the saturated sodium chloride solution in a crystallizer, heating the saturated sodium chloride solution at a constant temperature by using a water bath, evaporating the saturated sodium chloride solution at the temperature of 60 ℃, stirring the saturated sodium chloride solution at a stirring speed of 100r/min, evaporating the saturated sodium chloride solution for 6 hours until a large number of crystals are separated out, carrying out suction filtration on the crystals, and drying the crystals in an oven at the temperature of 60 ℃ for 2 hours to obtain a granular salt reference sample 1. The crystal shape was observed under a polarizing microscope (see FIG. 1), and the particle size of the crystal was measured to be 0.0425cm by a particle size analyzer.

Comparative example 2

Preparing 300mL of sodium chloride saturated solution into a crystallizer, adding mannitol with the mass being 20% of the mass of a solute of the sodium chloride saturated solution, heating the solution at a constant temperature by using a water bath, evaporating the solution at 60 ℃, stirring the solution at a stirring speed of 100r/min, evaporating the solution for 6 hours to separate out a large amount of crystals, carrying out suction filtration on the crystals, and drying the crystals in an oven at 60 ℃ for 2 hours to obtain a granular salt reference sample 2. The crystal shape was observed under a microscope (see FIG. 2), and the particle size of the crystal was measured by a particle sizer to be 0.0632 cm.

Examples 1 to 12

Examples 1-12 large-particle funnel crystalline salt samples 1-9, polyhedral salt samples 1-2, and spherical salt samples were prepared, respectively, in substantially the same manner as in comparative example 2, except for the type of additive, the amount of additive added (relative to the mass of solute sodium chloride in a saturated solution of sodium chloride), the evaporation temperature, the stirring rate during evaporation, and the evaporation time, and specific differences are shown in table 1. The particle sizes of the large particle funnel crystal salt sample 1-9, the polyhedral salt sample 1-2 and the spherical salt sample were measured with a ruler and a particle size analyzer, respectively, and the results are shown in table 1.

TABLE 1 preparation conditions and particle sizes of large particle funnel crystalline salt samples 1-9

As can be seen from Table 1, compared with the granular salt comparison sample 1-2, the polyhedral salt sample 1-2 and the spherical salt sample, the grain size of the large-grain funnel crystal salt sample 1-9 is obviously increased, and the large-grain sodium chloride crystal of the funnel-shaped crystal form can be prepared under the conditions of well controlling the stirring speed, the temperature, the time and the like.

Comparing the polyhedral salt sample 1 and the large-particle funnel crystal salt samples 1 to 3, it can be seen that funnel-shaped large-particle salts can be obtained by properly increasing the addition amounts of formamide and dimethylformamide, but the crystal particle size is reduced when the addition amounts of formamide and dimethylformamide are too high.

Comparing the large-particle funnel crystal salt samples 1 and 4-5 with the polyhedral salt sample 2, the evaporation temperature has great influence on the appearance and granularity of the large-particle funnel crystal salt, and when the temperature is low, the nucleation and growth of the crystal are difficult, funnel-shaped crystals are difficult to obtain, the yield is low, and the actual production is not facilitated; at higher temperatures, the crystals are predominantly nucleated due to excessive evaporation intensity, which reduces the average particle size of the funnel crystals.

Contrast large granule funnel crystal salt sample 1, 6-7, spherical salt sample can know, suitably improve stirring rate among the evaporation process and can make funnel crystal form looks better, and the granularity is more even, but when stirring rate was too big, the increase of the collision abrasion intensity between the crystal not only can reduce the brilliant granularity of funnel, but also can change the brilliant appearance of funnel, makes its wearing and tearing be spherical.

Comparing the large-particle funnel crystal salt samples 1 and 8-9, it can be seen that the evaporation time is too short, the funnel crystal is not completely grown, and the yield is low; the evaporation time is too long, a large amount of crystals collide and wear, and the particle size distribution of the crystals is not uniform, and when the evaporation time is 6 hours, the appearance of the funnel crystals is best, and the particle size is larger.

In conclusion, in the heating, stirring and evaporating process, the heating temperature is 60 ℃, the stirring speed is 100r/min, the evaporating time is 6h, and the large-particle funnel crystal salt with the particle size of 0.6cm is successfully prepared, wherein the mass of the added formamide and the mass of the added dimethylformamide are respectively 20 percent and 2 percent of the mass of the solute of the saturated solution of the sodium chloride.

Example 13

Respectively with granule salt comparison sample 1, granule salt comparison sample 2, large granule funnel crystal salt sample 1, large granule funnel crystal salt sample 5, spherical salt sample place ambient temperature 23 ℃, ambient humidity 15% down 40 days, observe each sample and discover granule salt comparison sample 1, granule salt comparison sample 2 all have the caking phenomenon of different degrees, and spherical salt sample is a little a lot of caking, nevertheless compare in granule salt comparison sample 1, granule salt comparison sample 2, the caking volume of spherical salt sample obviously reduces. The large-particle funnel crystal salt sample 1 and the large-particle funnel crystal salt sample 5 have no obvious caking phenomenon, particularly the large-particle funnel crystal salt sample 1 hardly has caking phenomenon, and has good fluidity, and the phenomenon is caused because the funnel crystal salt has small contact area compared with a cubic salt or a spherical salt crystal, has good fluidity and is not easy to cake, and the funnel crystal salt prepared by the invention has larger granularity and is not easy to aggregate and cake.

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