Large-Particle Spherical Salt and Preparation Method Thereof

Abstract

A large-particle spherical salt with a particle size of 400-950 μm and a sphericity of 0.5-1.0 is disclosed, which overcomes the existing difficulty in this field for larger particle size as well as higher sphericity. A preparation method of the large-particle spherical salt is also disclosed, wherein in one preparation process, 2% of gum arabic (based on the mass percentage of solute sodium chloride in a sodium chloride saturated solution) is added, and under conditions of an evaporating temperature of 60° C. a stirring rate of 350 rpm, and an evaporating time of 8 hours, a large-particle spherical salt with a particle size of 921.593 μm and an average sphericity of 0.904 is successfully prepared. The large-particle spherical salt prepared by the method has a uniform particle size distribution and good appearance, can be combined with other substances, adding some extra value to the salt. Meanwhile, the large-particle spherical salt prepared by the method has a high safety grade (e.g.: food grade) and can be used as edible salt, nutrient salt or foot bath salt.

Claims

1. A large-particle, spherical sodium chloride, having a particle size of 400-950 μm and a sphericity of 0.5-1.0, obtained by evaporating a saturated sodium chloride solution into which 0.5-5 mass % of gum arabic relative to a mass of sodium chloride in the saturated sodium chloride solution is added.

2. The large-particle spherical sodium chloride in claim 1, having an average particle size of 921.593 μm, and an average sphericity of 0.904, wherein 2 mass % of the gum arabic is added to the saturated solution of sodium chloride.

3. A method for preparing a large-particle spherical salt, comprising: (1) preparing a saturated solution of sodium chloride in a crystallizer, adding gum arabic into the saturated solution, then heating, stirring and evaporating the saturated solution to form crystals; and (2) filtering and drying the crystals to obtain the large-particle spherical salt.

4. The preparation method in claim 3, wherein the gum arabic is present in a mass percentage of 0.5-5% of a mass of the sodium chloride in the saturated solution, the saturated solution is heated at a temperature of 55-75° C., the saturated solution is stirred at a rate of 300-400 rpm, and the saturated solution is evaporated for a time of 4-12 hours.

5. The preparation method in claim 4, wherein the mass percentage of the gum arabic is 2% of the sodium chloride in the saturated solution, the temperature is 60° C., the rate is 350 rpm, and the evaporation time is 8 hours.

6. The preparation method in claim 4, further comprising inducing crystals for a period of 38 to 65 min.

7. The method in claim 3, wherein the saturated solution of sodium chloride has a temperature of 55 to 75° C. while inducing the crystals.

8. The method in claim 3, wherein the crystals are dried at a temperature of 60° C. for a time of 2 hours.

9. A large-particle, spherical sodium chloride, having a particle size of 400-950 μm and a sphericity of 0.5-1.0.

10. The large-particle spherical sodium chloride in claim 9, wherein the sphericity is 0.52-0.95.

11. The large-particle spherical sodium chloride in claim 10, wherein the particle size is 600-925 μm.

12. The large-particle spherical sodium chloride in claim 9, wherein the sphericity is 0.685-0.904.

13. The large-particle spherical sodium chloride in claim 12, wherein the particle size is 684-922 μm.

14. The large-particle spherical sodium chloride in claim 9, wherein the sphericity is 0.721-0.904.

15. The large-particle spherical sodium chloride in claim 14, wherein the particle size is 739.388-921.593 μm.

16. The large-particle spherical sodium chloride in claim 9, having an average particle size of 921.593 μm, and an average sphericity of 0.904.

Description

DRAWINGS

[0027] FIG. 1 is an EMS map of the surface of the particulate salt prepared in comparative example 1;

[0028] FIG. 2 is an EMS map of the surface of the particulate salt prepared in comparative example 2;

[0029] FIG. 3 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 1;

[0030] FIG. 4 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 2;

[0031] FIG. 5 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 3;

[0032] FIG. 6 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 4;

[0033] FIG. 7 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 5;

[0034] FIG. 8 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 6;

[0035] FIG. 9 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 7;

[0036] FIG. 10 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 8;

[0037] FIG. 11 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 9;

[0038] FIG. 12 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 10

[0039] FIG. 13 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 11;

[0040] FIG. 14 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 12; and

[0041] FIG. 15 is an EMS map of the surface of the large particle spherical salt prepared in exemplary embodiment 2.

[0042] The magnification of FIGS. 1-14 is 40, and the magnification of FIG. 15 is 4.

DETAILED DESCRIPTION

[0043] The present invention will be described below with reference to specific examples, but the embodiments of the present invention are not limited thereto.

[0044] The morphology of the large-particle spherical salt was observed under a polarization microscope (EMS) in the following comparative examples and exemplary embodiments. The particle size and particle size distribution of the large-particle spherical salt were measured by a particle size analyzer, and the sphericity of the large-particle spherical salt was measured by a particle shape meter.

Comparative Example 1

[0045] 300 mL of a saturated solution of sodium chloride was prepared, the saturated solution was placed in a crystallizer, heated at a constant temperature in a water bath, and evaporated at a temperature of 60° C. for 8 hours with stirring at a stirring speed of 350 rpm, until a large number of crystals were formed. The saturated solution was filtered and the crystals were dried in an oven at a temperature of 60° C. for 2 hours to obtain a granular salt reference sample 1. The crystal shape was observed under a polarizing microscope (see FIG. 1). The particle size of the crystal was 382.744 in as measured by a particle size analyzer, and the sphericity of the crystal was 0.136 as measured by a particle shape meter.

Comparative Example 2

[0046] 300 mL of a saturated solution of sodium chloride was prepared in a crystallizer. 2% glycine by mass of the sodium chloride in the saturated solution was added, heated at a constant temperature in a water bath, and evaporated at 60° C. for 8 hours with stirring the solution at a stirring speed of 350 rpm to form a large number of crystals. The solution was filtered and the crystals were dried in an oven at 60° C. for 2 hours to obtain a granular salt reference sample 2. The shape of the crystal was observed under a microscope (see FIG. 2). The particle size of the crystal was 391.628 μm as measured by a particle size analyzer, and the sphericity of the crystal was 0.426 as measured by a particle shape meter.

Examples 1 to 12

[0047] In examples 1-12, large particle spherical salt samples 1-12 were prepared, respectively, using substantially the same procedure as in comparative example 2, except that the additive, the amount of additive added (relative to the mass of the sodium chloride in the saturated solution), the evaporation temperature, the stirring rate during evaporation, and the evaporation time were varied, as shown in table 1. The particle size and particle size distribution of the large-particle spherical salt samples 1 to 12 were measured by a particle size analyzer, and the sphericity of the large-particle spherical salt samples 1 to 12 was measured by a particle shape meter. The results are shown in Table 1.

TABLE-US-00001 TABLE 1 Preparation conditions for large particle spherical salt samples 1-12 and their particle sizes and sphericities Additive Evaporation Stirring Evaporation Particle Embodiment Sample Additive percentage (%) Temp (° C.) rate (rpm) duration (h) size (μm) Sphericity Comparative Particle salt N/A N/A 60 350 8 382.744 0.136 example 1 comparative example 1 Comparative Particle salt Glycine 2 60 350 8 391.628 0.426 example 2 comparative example 2 Embodiment Large particle gum 0.5 60 350 8 403.597 0.596 1 spherical salt arabic sample 1 Embodiment Large particle gum 2 60 350 8 921.593 0.904 2 spherical salt arabic sample 2 Embodiment Large particle gum 5 60 350 8 748.625 0.685 3 spherical salt arabic sample 3 Embodiment Large particle gum 2 60 250 8 388.942 0.316 4 spherical salt arabic sample 4 Embodiment Large particle gum 2 60 300 8 789.642 0.721 5 spherical salt arabic sample 5 Embodiment Large particle gum 2 60 400 8 414.051 0.532 6 spherical salt arabic sample 6 Embodiment Large particle gum 2 60 350 2 486.354 0.236 7 spherical salt arabic sample 7 Embodiment Large particle gum 2 60 350 4 739.388 0.831 8 spherical salt arabic sample 8 Embodiment Large particle gum 2 60 350 12 684.592 0.774 9 spherical salt arabic sample 9 Embodiment Large particle gum 2 45 350 8 604.715 0.154 10  spherical salt arabic  sample 10 Embodiment Large particle gum 2 55 350 8 893.569 0.892 11  spherical salt arabic  sample 11 Embodiment Large particle gum 2 75 350 8 628.939 0.528 12  spherical salt arabic  sample 12

[0048] As can be seen from Table 1, compared with the granular salt in comparative samples 1-2, the particle sizes of the large-particle spherical salt samples 1-12 are significantly increased, and the sphericities are also significantly improved under the conditions of well-controlled stirring rate, temperature, evaporation duration and the like.

[0049] Comparing the large particle spherical salt samples 1 to 3, it can be seen that adding more gum arabic increases the particle size and sphericity of the large particle spherical salt, but when the amount of gum arabic increases beyond a certain amount, the particle size and sphericity are reduced. Comparing the large particle spherical salt samples 2 and 4-6, it can be seen that the particle size and sphericity of the large particle spherical salt can be increased by properly increasing the stirring rate during the evaporation process, but the particle size and sphericity can decrease when the stirring rate increases beyond a certain rate. Comparing the large-particle spherical salt samples 2 and 7-9, it can be seen that when the evaporation time is less than the ideal length, the crystals are not completely formed, and the particle size and the sphericity of the crystals are relatively low. When the evaporation time is longer than ideal, a large number of crystals collide and wear, and the particle size and the sphericity of the crystals are relatively low. When the evaporation duration is 8 hours, the sphericity of the crystals is the best, and the particle size is the largest. Comparing the large-particle spherical salt samples 2 and 10-12, it can be seen that the evaporation temperature has a great influence on the particle size and sphericity of the large-particle spherical salt, when the temperature is less than ideal, the nucleation and growth of the crystal is relatively difficult, leading to relatively small particle size and sphericity of the crystal, a relatively low yield and relative difficulty for actual production. When the temperature is relatively high, the particle size and sphericity are relatively low due to over-evaporation Under ideal temperature conditions, the sphericity of the salt reached as high as 0.904 at an evaporation temperature of 60° C., and when the evaporation temperature was slightly decreased to 55° C., the sphericity still reached 0.892.

Embodiment 13

[0050] The granular salt reference sample 1, the granular salt reference sample 2, the large-particle spherical salt sample 2 and the large-particle spherical salt sample 6 were respectively stored at an ambient temperature of 23° C. and an ambient humidity of 15% for 30 days, and each sample was observed. The granular salt reference sample 1 and the granular salt reference sample 2 showed caking phenomena of different degrees, but the large-particle spherical salt sample 2 and the large-particle spherical salt sample 6 had no obvious caking phenomenon. In particular, the large-particle spherical salt sample 2 shows almost no caking phenomenon and has good fluidity, and the reason for the phenomenon is that the spherical salt has a smaller contact area and better fluidity than a cubic salt crystal. Also, the spherical salt prepared by this invention has larger particle size, which does not easily aggregate and agglomerate