阅读说明：本技术 一种从盐湖中制备氯化钾的方法、提高氯化钾晶体颗粒粒度的方法 (Method for preparing potassium chloride from salt lake and method for improving granularity of potassium chloride crystal particles ) 是由 李海朝 张净净 石成龙 张丽娟 祝永强 王广乐 于 2020-11-30 设计创作，主要内容包括：本申请提供一种从盐湖中制备氯化钾的方法、提高氯化钾晶体颗粒粒度的方法,属于化工提纯技术领域。从盐湖中制备氯化钾的方法包括：从盐湖中提取并制备饱和氯化钾溶液,将饱和氯化钾溶液和盐酸溶液混合使氯化钾晶体颗粒析出。本申请通过在饱和氯化钾溶液中加入盐酸溶液以增加溶液中Cl~-的量,氯化钾能够在较快时间内结晶析出并且得到粒度较大的氯化钾晶体颗粒。从而使得从盐湖出产的氯化钾晶体颗粒较大,其粒径可以达到0.1～0.2mm,同时,由于氯化钾的结晶速率提高,能够在相同时间内结晶得到更多的氯化钾晶体颗粒,进而提高产量。(The application provides a method for preparing potassium chloride from a salt lake and a method for improving the granularity of potassium chloride crystal particles, and belongs to the technical field of chemical purification. The method for preparing potassium chloride from the salt lake comprises the following steps: extracting and preparing saturated potassium chloride solution from salt lake, and mixing the saturated potassium chloride solution and hydrochloric acid solution to separate out potassium chloride crystal particles. The method is used for increasing Cl in a saturated potassium chloride solution by adding a hydrochloric acid solution into the saturated potassium chloride solution ‑ In an amount that allows the potassium chloride to crystallize out in a relatively rapid time and results in potassium chloride crystal particles of relatively large size. Therefore, potassium chloride crystal particles produced from the salt lake are large, the particle size of the potassium chloride crystal particles can reach 0.1-0.2 mm, and meanwhile, as the crystallization rate of potassium chloride is increased, more potassium chloride crystal particles can be obtained through crystallization in the same time, and further the yield is increased.)

1. A method for preparing potassium chloride from a salt lake, which is characterized by comprising the following steps: saturated potassium chloride solution is extracted and prepared from the salt lake, and the saturated potassium chloride solution and hydrochloric acid solution are mixed to separate out potassium chloride crystal particles.

2. The method for preparing potassium chloride from a salt lake according to claim 1, wherein the molar concentration of the hydrochloric acid is 1-10 mol/L.

3. The method for preparing potassium chloride from a salt lake according to claim 1, wherein the molar concentration of the hydrochloric acid is 1-5 mol/L.

4. The method for preparing potassium chloride from a salt lake according to claim 1, wherein the molar ratio of the chloride ions in the saturated potassium chloride solution to the chloride ions in the hydrochloric acid solution is 4: 1-20: 1.

5. The method for preparing potassium chloride from a salt lake according to claim 1, wherein the molar ratio of the chloride ions in the saturated potassium chloride solution to the chloride ions in the hydrochloric acid solution is 10: 1-20: 1.

6. The method for preparing potassium chloride from a salt lake according to claim 1, wherein the molar concentration of the hydrochloric acid is 1-5 mol/L, and the molar ratio of the chloride ions in the saturated potassium chloride solution to the chloride ions in the hydrochloric acid solution is 10: 1-20: 1.

7. The method for preparing potassium chloride from a salt lake according to any one of claims 1 to 6, wherein the potassium chloride crystal particles are precipitated at 15 to 35 ℃.

8. The method for preparing potassium chloride from a salt lake according to any one of claims 1 to 6, wherein the saturated potassium chloride solution is a saturated potassium chloride solution at 15 to 35 ℃.

9. A method for increasing the particle size of potassium chloride crystal particles, which is characterized by comprising the following steps: mixing saturated potassium chloride solution and hydrochloric acid solution, and crystallizing.

10. The method for increasing the particle size of potassium chloride crystals as claimed in claim 9, wherein the crystallization time is 6-15 h.

Technical Field

The application relates to the technical field of chemical purification, in particular to a method for preparing potassium chloride from a salt lake and a method for improving the granularity of potassium chloride crystal particles.

Background

Potassium salt is one of three agricultural fertilizers, belongs to a strategic resource necessary for developing agriculture, 94 percent of potassium salt products are applied to the manufacturing of potassium fertilizers, and the rest are applied to the industrial aspect. The potassium chloride is a basic raw material for manufacturing various agricultural fertilizers, can be used for preparing compound fertilizers or used as potassium fertilizers for direct use, has quick fertilizer effect, can be directly applied to farmlands, can increase the moisture of the lower layer of soil, has the drought resistance effect, is a nutrient substance necessary for the growth of crops, and can be used as a base fertilizer and an additional fertilizer. Most of potassium salt in the world is used as potassium fertilizer, accounting for about 95 percent, and is widely applied to grains, soybeans, cotton and other crops to promote photosynthesis of the crops so as to achieve the purposes of improving the quality of the crops and increasing the yield of the crops. The potassium exists in the form of free potassium ion in the plant body, promotes the metabolism of carbohydrate and nitrogen, and regulates the activity of various mineral nutrient elements to prevent the plant from withering. According to investigation, 84% of land is deficient in potassium, but potassium resources are relatively deficient, so that the supply and demand gaps are large, the development of agriculture is severely restricted, and the application prospect is very wide along with the popularization of potassium fertilizers in the field of agriculture.

The existing potash fertilizer-potassium chloride is generally extracted from salt lake. Firstly, potassium chloride solution is extracted from salt lake, and then the potassium chloride solution is exposed to the sun to evaporate the solvent to obtain potassium chloride particles. However, potassium chloride particles produced by the solvent evaporation method have a small particle size. The potassium chloride particles have poor adhesion to the ground, and are easy to float and separate from the ground in the wind after fertilization, so that the fertilizing amount is large or fertilization needs to be performed again.

Disclosure of Invention

The application provides a method for preparing potassium chloride from a salt lake and a method for increasing the granularity of potassium chloride crystal particles, which can prepare potassium chloride crystal particles with larger granularity from the salt lake and increase the yield.

The embodiment of the application is realized as follows:

in a first aspect, the present application provides a method for preparing potassium chloride from a salt lake, comprising: extracting and preparing saturated potassium chloride solution from salt lake, and mixing the saturated potassium chloride solution and hydrochloric acid solution to separate out potassium chloride crystal particles.

In the technical scheme, the hydrochloric acid solution is added into the saturated potassium chloride solution to increase Cl in the solution^-In an amount that allows the potassium chloride to crystallize out in a relatively rapid time and results in potassium chloride crystal particles of relatively large size. Therefore, potassium chloride crystal particles produced from the salt lake are large, the particle size of the potassium chloride crystal particles can reach 0.1-0.2 mm, and meanwhile, as the crystallization rate of potassium chloride is increased, more potassium chloride crystal particles can be obtained through crystallization in the same time, and further the yield is increased.

In combination with the first aspect, in a first possible example of the first aspect of the present application, the hydrochloric acid has a molar concentration of 1 to 10 mol/L.

In the above example, considering the cost of hydrochloric acid, the cost of the hydrochloric acid solution with the molar concentration of 1-10 mol/L is low, and the cost for preparing the potash fertilizer can be reduced.

In a second possible example of the first aspect of the present application in combination with the first aspect, the hydrochloric acid has a molar concentration of 1 to 5 mol/L.

In a third possible example of the first aspect of the present application, in combination with the first aspect, a molar ratio of chloride ions in the saturated potassium chloride solution to chloride ions in the hydrochloric acid solution is 4:1 to 20: 1.

With reference to the first aspect, in a fourth possible example of the first aspect of the present application, a molar ratio of chloride ions in the saturated potassium chloride solution to chloride ions in the hydrochloric acid solution is 10:1 to 20: 1.

In a fifth possible example of the first aspect of the present application, in combination with the first aspect, the hydrochloric acid has a molar concentration of 1 to 5mol/L, and a molar ratio of chloride ions in the saturated potassium chloride solution to chloride ions in the hydrochloric acid solution is 10:1 to 20: 1.

In the above example, when hydrochloric acid with a molar concentration of 1-5 mol/L is selected and the molar ratio of chloride ions in the saturated potassium chloride solution to chloride ions in the hydrochloric acid solution is 10: 1-20: 1, potassium chloride crystal particles with a particle size of 0.12-0.18 mm can be prepared, and the crystallization rate is highCan reach 1.7 multiplied by 10^-6Kg/(m²·s)。

In a sixth possible example of the first aspect of the present application in combination with the first aspect, the potassium chloride crystal particles are precipitated at 15 to 35 ℃.

In the above example, the crystallization is performed at normal temperature, so that energy conservation, emission reduction and cost reduction can be realized.

With reference to the first aspect, in a seventh possible example of the first aspect of the present application, the saturated potassium chloride solution is a saturated potassium chloride solution at 15 to 35 ℃.

In a second aspect, the present application provides a method for increasing the particle size of potassium chloride crystals, comprising: mixing saturated potassium chloride solution and hydrochloric acid solution, and crystallizing.

In the technical scheme, the hydrochloric acid solution is added into the saturated potassium chloride solution to increase Cl in the solution^-In an amount that allows the potassium chloride to crystallize out in a relatively rapid time and results in potassium chloride crystal particles of relatively large size.

In a first possible example of the second aspect of the present application in combination with the second aspect, the crystallization time is 6 to 15 hours.

In the above example, after mixing the saturated potassium chloride solution with the hydrochloric acid solution, standing for 6-15 h to obtain potassium chloride crystal particles with larger particle size.

Detailed Description

Embodiments of the present application will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present application and should not be construed as limiting the scope of the present application. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The following description is specific to a method for preparing potassium chloride from a salt lake and a method for increasing the particle size of potassium chloride crystal particles in the embodiments of the present application:

the application provides a method for preparing potassium chloride from a salt lake, which comprises the following steps: extracting and preparing saturated potassium chloride solution from salt lake, and mixing the saturated potassium chloride solution and hydrochloric acid solution to separate out potassium chloride crystal particles.

The method is used for increasing Cl in a saturated potassium chloride solution by adding a hydrochloric acid solution into the saturated potassium chloride solution^-In an amount that allows the potassium chloride to crystallize out in a relatively rapid time and results in potassium chloride crystal particles of relatively large size. Therefore, potassium chloride crystal particles produced from the salt lake are large, the particle size of the potassium chloride crystal particles can reach 0.1-0.2 mm, and meanwhile, as the crystallization rate of potassium chloride is increased, more potassium chloride crystal particles can be obtained through crystallization in the same time, and further the yield is increased.

The saturated potassium chloride solution in the present application refers to potassium chloride in a saturated state in a solution system, but some other unsaturated or saturated compounds may also be dissolved in the saturated potassium chloride solution. For example, the saturated potassium chloride solution may contain small amounts of magnesium ions, sodium ions, sulfate ions, and the like.

The process technology for preparing potassium chloride from sylvite comprises the following steps: cold decomposition-flotation, reverse flotation-cold crystallization and hot melt crystallization. While salt lakes are used as a base for potassium chloride production, which relies on sodium-containing carnallite obtained from salt fields. Carnallite mainly comprises (KCl MgCl)₂·6H₂O) and potassium chloride (KCl) with very small amount of Mg₄Cl(OH)₇·6H₂And (4) output in the form of O. The sodium-containing mineral is mainly sodium halite (NaCl), and the magnesium-containing mineral is mainly carnallite (KCl MgCl)₂·6H₂O) and bischofite (MgCl)₂·2H₂O). Carnallite is an important industrial raw material for manufacturing potash fertilizers and extracting magnesium metal, and table 1 shows the composition of low sodium carnallite.

TABLE 1 composition of low-sodium carnallite

The existing method for preparing potassium chloride from salt lakes comprises: saturated potassium chloride solution is prepared by taking carnallite as a raw material, and then the saturated potassium chloride solution is exposed to the sun to evaporate the hydrosolvent, so that potassium chloride crystal particles are separated out.

This application can make potassium chloride can obtain the potassium chloride crystal of large granule in the crystallization in short time through adding hydrochloric acid in to saturated potassium chloride solution, improves crystallization efficiency to increase of production. The prepared large-particle potassium chloride crystals can be effectively attached to the surface of the land, so that the fertilizing amount is reduced, secondary fertilization is not needed, and the application of potassium chloride in the fertilizer is more convenient.

The method for preparing the low-sodium carnallite from the salt lake specifically comprises the following steps:

taking carnallite from the salt lake, transferring the liquid into a flotation tank by adopting a solid-liquid separation method, adding a flotation agent to float sodium ions, reducing the number of the sodium ions in the solution, then entering a belt tank crystallizer to crystallize, wherein most of magnesium ions exist in the solution to remove part of magnesium ions, and finally obtaining the low-sodium carnallite.

Optionally, the molar concentration of the hydrochloric acid is 1-10 mol/L.

Optionally, the molar concentration of the hydrochloric acid is 1-5 mol/L.

In one embodiment of the present application, the hydrochloric acid has a molar concentration of 5 mol/L. In other embodiments of the present application, the hydrochloric acid may also have a molar concentration of 1mol/L, 2mol/L, 3mol/L, 4mol/L, 6mol/L, 7mol/L, 8mol/L, 9mol/L, or 10 mol/L.

In the present application, the concentration of hydrochloric acid is not limited, and any concentration of hydrochloric acid may be used as the hydrochloric acid in theory. However, the inventors have found that the particle size of potassium chloride crystal particles obtained by direct evaporative crystallization of a solvent in a saturated potassium chloride solution without adding hydrochloric acid is 0.1mm, the particle size of potassium chloride crystal particles obtained by crystallization with addition of 1mol/L hydrochloric acid solution is 0.12mm, the particle size of potassium chloride crystal particles obtained by crystallization with addition of 2mol/L hydrochloric acid solution is 0.14mm, the particle size of potassium chloride crystal particles obtained by crystallization with addition of 3mol/L hydrochloric acid solution is 0.15mm, the particle size of potassium chloride crystal particles obtained by crystallization with addition of 4mol/L hydrochloric acid solution is 0.17mm, and the particle size of potassium chloride crystal particles obtained by crystallization with addition of 5mol/L hydrochloric acid solution is 0.18 mm. While the largest potassium chloride crystal particles precipitated from the saturated potassium chloride solution had a particle size of 0.2 mm.

From the above rules, the inventors found that even if the concentration of the hydrochloric acid solution is increased on the basis of 5mol/L, the particle size of the potassium chloride crystal particles can be increased only from 0.18mm to 0.2mm, and the increase is not large. Moreover, the hydrochloric acid with higher concentration is expensive, which increases the production cost of the potash fertilizer. A hydrochloric acid solution with the concentration of 1-5 mol/L is selected, so that the particle size of potassium chloride crystal particles can be increased to a certain extent, and the production cost of the potassium fertilizer can be strictly controlled.

The molar ratio of the chloride ions in the saturated potassium chloride solution to the chloride ions in the hydrochloric acid solution is 4: 1-20: 1.

Optionally, the molar ratio of the chloride ions in the saturated potassium chloride solution to the chloride ions in the hydrochloric acid solution is 8: 1-15: 1.

In one embodiment of the present application, the molar ratio of chloride ions in the saturated potassium chloride solution to chloride ions in the hydrochloric acid solution may be 10: 1. In other embodiments of the present application, the molar ratio of chloride ions in the saturated potassium chloride solution to chloride ions in the hydrochloric acid solution may also be 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, or 20: 1.

In order to reduce energy consumption and save cost, the saturated potassium chloride solution is a saturated potassium chloride solution at normal temperature, namely a saturated potassium chloride solution at 15-35 ℃.

Adding a certain volume of hydrochloric acid solution into saturated potassium chloride solution at normal temperature, and standing and crystallizing at normal temperature to obtain potassium chloride crystal particles.

Optionally, the hydrochloric acid solution is normal-temperature hydrochloric acid solution, and the temperature of the hydrochloric acid solution is 15-35 ℃.

Optionally, the molar concentration of the hydrochloric acid is 1-5 mol/L, and the molar ratio of chloride ions in the saturated potassium chloride solution to chloride ions in the hydrochloric acid solution is 10: 1-20: 1.

Selecting hydrochloric acid with the molar concentration of 1-5 mol/L, wherein the molar ratio of chloride ions in a saturated potassium chloride solution to chloride ions in a hydrochloric acid solution is 10:1 ℃At the ratio of 20:1, potassium chloride crystal particles with the particle size of 0.12-0.18 mm can be easily obtained at normal temperature, and the crystallization rate can reach 1.7 multiplied by 10^-6Kg/(m²·s)。

Optionally, the molar concentration of the hydrochloric acid is 3-5 mol/L, and the molar ratio of chloride ions in the saturated potassium chloride solution to chloride ions in the hydrochloric acid solution is 12: 1-18: 1.

Selecting hydrochloric acid with the molar concentration of 3-5 mol/L, and easily obtaining potassium chloride crystal particles with the particle size of 0.15-0.18 mm at normal temperature when the molar ratio of chloride ions in the saturated potassium chloride solution to chloride ions in the hydrochloric acid solution is 12: 1-18: 1, wherein the crystallization rate can reach 3.4 multiplied by 10^-6Kg/(m²·s)。

Optionally, the molar concentration of the hydrochloric acid is 4-5 mol/L, and the molar ratio of chloride ions in the saturated potassium chloride solution to chloride ions in the hydrochloric acid solution is 14: 1-16: 1.

When hydrochloric acid with the molar concentration of 4-5 mol/L is selected and the molar ratio of chloride ions in a saturated potassium chloride solution to chloride ions in a hydrochloric acid solution is 14: 1-16: 1, potassium chloride crystal particles with the particle size of 0.17-0.18 mm can be easily obtained at normal temperature, and the crystallization rate can reach 4.9 multiplied by 10^-6Kg/(m²·s)。

Optionally, the molar concentration of the hydrochloric acid is 4-5 mol/L, and the molar ratio of chloride ions in the saturated potassium chloride solution to chloride ions in the hydrochloric acid solution is 14: 1-16: 1.

When hydrochloric acid with the molar concentration of 5mol/L is selected and the molar ratio of chloride ions in a saturated potassium chloride solution to chloride ions in a hydrochloric acid solution is 15:1, potassium chloride crystal particles with the particle size of 0.18mm can be easily obtained at normal temperature, and the crystallization rate can reach 5.9 multiplied by 10^-6Kg/(m²·s)。

The present application also provides a method for increasing the particle size of potassium chloride crystals, comprising: mixing saturated potassium chloride solution and hydrochloric acid solution, and crystallizing.

The method is used for increasing Cl in a saturated potassium chloride solution by adding a hydrochloric acid solution into the saturated potassium chloride solution^-In an amount that allows the potassium chloride to crystallize out in a relatively rapid time and results in potassium chloride crystal particles of relatively large size.

Optionally, the crystallization time is 6-15 h.

In one embodiment of the present application, the crystallization time may be 10 hours. In other embodiments herein, the crystallization time may also be 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, or 15 h.

The following examples are provided to further describe the method for preparing potassium chloride from salt lake and the method for increasing the particle size of potassium chloride crystal particles in detail.

Example 1

The embodiment of the application provides a method for improving the granularity of potassium chloride crystal particles, which comprises the following steps:

1. preparing solution

Saturated potassium chloride aqueous solution and hydrochloric acid aqueous solution with the concentration of 1mol/L are prepared at the temperature of 20 ℃.

2. Preparation of Potassium chloride crystals

Adding 11.3mL of 1mol/L hydrochloric acid aqueous solution into 50mL of saturated potassium chloride aqueous solution to prepare a mixed solution, standing the mixed solution at 20 ℃ for 10 hours, and precipitating potassium chloride crystal particles in the mixed solution.

3. Characterization of

The time for the dissolution to occur and crystallization was observed and the particle size distribution of the crystals was determined for potassium chloride crystals using a belgian fully automatic static dry and wet particle size analyzer (500Nano XY).

Example 2

The embodiment of the application provides a method for improving the granularity of potassium chloride crystal particles, which comprises the following steps:

1. preparing solution

Saturated potassium chloride aqueous solution and hydrochloric acid aqueous solution with the concentration of 2mol/L are prepared at the temperature of 20 ℃.

2. Preparation of Potassium chloride crystals

5.7mL of 2mol/L hydrochloric acid aqueous solution was added to 50mL of a saturated potassium chloride aqueous solution to prepare a mixed solution, and then the mixed solution was allowed to stand at 20 ℃ for 10 hours to precipitate potassium chloride crystal particles in the mixed solution.

3. Characterization of

The time for the dissolution to occur and crystallization was observed and the particle size distribution of the crystals was determined for potassium chloride crystals using a belgian fully automatic static dry and wet particle size analyzer (500Nano XY).

Example 3

The embodiment of the application provides a method for improving the granularity of potassium chloride crystal particles, which comprises the following steps:

1. preparing solution

Saturated potassium chloride aqueous solution and hydrochloric acid aqueous solution with the concentration of 3mol/L are prepared at the temperature of 20 ℃.

2. Preparation of Potassium chloride crystals

3.8mL of 3mol/L hydrochloric acid aqueous solution was added to 50mL of saturated potassium chloride aqueous solution to prepare a mixed solution, and then the mixed solution was allowed to stand at 20 ℃ for 10 hours to precipitate potassium chloride crystal particles in the mixed solution.

3. Characterization of

The time for the dissolution to occur and crystallization was observed and the particle size distribution of the crystals was determined for potassium chloride crystals using a belgian fully automatic static dry and wet particle size analyzer (500Nano XY).

Example 4

The embodiment of the application provides a method for improving the granularity of potassium chloride crystal particles, which comprises the following steps:

1. preparing solution

Saturated potassium chloride aqueous solution and hydrochloric acid aqueous solution with the concentration of 4mol/L are prepared at the temperature of 20 ℃.

2. Preparation of Potassium chloride crystals

2.8mL of 4mol/L hydrochloric acid aqueous solution was added to 50mL of saturated potassium chloride aqueous solution to prepare a mixed solution, and then the mixed solution was allowed to stand at 20 ℃ for 10 hours to precipitate potassium chloride crystal particles in the mixed solution.

3. Characterization of

The time for the dissolution to occur and crystallization was observed and the particle size distribution of the crystals was determined for potassium chloride crystals using a belgian fully automatic static dry and wet particle size analyzer (500Nano XY).

Example 5

The embodiment of the application provides a method for improving the granularity of potassium chloride crystal particles, which comprises the following steps:

1. preparing solution

Saturated potassium chloride aqueous solution and hydrochloric acid aqueous solution with the concentration of 5mol/L are prepared at the temperature of 20 ℃.

2. Preparation of Potassium chloride crystals

Adding 2.3mL of 5mol/L hydrochloric acid aqueous solution into 50mL of saturated potassium chloride aqueous solution to prepare a mixed solution, standing the mixed solution at 20 ℃ for 10 hours, and separating out potassium chloride crystal particles from the mixed solution.

3. Characterization of

The time for the dissolution to occur and crystallization was observed and the particle size distribution of the crystals was determined for potassium chloride crystals using a belgian fully automatic static dry and wet particle size analyzer (500Nano XY).

Example 6

The embodiment of the application provides a method for improving the granularity of potassium chloride crystal particles, which comprises the following steps:

1. preparing solution

Saturated potassium chloride aqueous solution and hydrochloric acid aqueous solution with the concentration of 5mol/L are prepared at the temperature of 20 ℃.

2. Preparation of Potassium chloride crystals

Adding 8.5mL of 5mol/L hydrochloric acid aqueous solution into 50mL of saturated potassium chloride aqueous solution to prepare a mixed solution, standing the mixed solution at 20 ℃ for 8 hours, and precipitating potassium chloride crystal particles in the mixed solution.

3. Characterization of

The time for the dissolution to occur and crystallization was observed and the particle size distribution of the crystals was determined for potassium chloride crystals using a belgian fully automatic static dry and wet particle size analyzer (500Nano XY).

Example 7

The embodiment of the application provides a method for improving the granularity of potassium chloride crystal particles, which comprises the following steps:

1. preparing solution

Saturated potassium chloride aqueous solution and hydrochloric acid aqueous solution with the concentration of 5mol/L are prepared at the temperature of 20 ℃.

2. Preparation of Potassium chloride crystals

1.7mL of 5mol/L hydrochloric acid aqueous solution was added to 50mL of a saturated potassium chloride aqueous solution to prepare a mixed solution, and then the mixed solution was allowed to stand at 20 ℃ for 15 hours to precipitate potassium chloride crystal particles in the mixed solution.

3. Characterization of

The time for the dissolution to occur and crystallization was observed and the particle size distribution of the crystals was determined for potassium chloride crystals using a belgian fully automatic static dry and wet particle size analyzer (500Nano XY).

Comparative example 1

The comparative example of the application provides a method for improving the granularity of potassium chloride crystal particles, which comprises the following steps:

1. preparing solution

Saturated potassium chloride aqueous solution was prepared at 20 ℃.

2. Preparation of Potassium chloride crystals

And (3) standing the saturated potassium chloride aqueous solution at the temperature of 20 ℃ for 24 hours, and separating out potassium chloride crystal particles from the mixed solution.

3. Characterization of

The time for the dissolution to occur and crystallization was observed and the particle size distribution of the crystals was determined for potassium chloride crystals using a belgian fully automatic static dry and wet particle size analyzer (500Nano XY).

Test example 1

The crystallization rates of the potassium chloride crystals of examples 1 to 9 and comparative example 1 and the particle diameters of the obtained potassium chloride crystals were counted, as shown in table 2.

TABLE 2 crystallization Rate of Potassium chloride crystals and particle size of the Potassium chloride crystals obtained

Item	Crystallization time (h)	Crystallization Rate x 10-6Kg/(m2·s)	Particle size (mm)
				Example 1	10	1.7510	0.12
Example 2	10	2.7806	0.14
				Example 3	10	3.4200	0.15
Example 4	10	4.9785	0.17
				Example 5	10	5.9097	0.18
Example 6	8	5.9563	0.16
				Example 7	15	1.6152	0.11
Comparative example 1	≥24	1.10133	0.10

From the above, when the concentration of hydrochloric acid is sequentially increased, the crystallization rate of potassium chloride is sequentially increased, and the obtained potassium chloride crystal particles are sequentially increased;

when the molar ratio of the chloride ions in the saturated potassium chloride solution to the chloride ions in the hydrochloric acid solution is 15:1, the obtained potassium chloride crystal particles are large, when the molar ratio of the chloride ions in the saturated potassium chloride solution to the chloride ions in the hydrochloric acid solution is 4:1, the crystallization rate of potassium chloride becomes large, but the obtained potassium chloride crystal particles become small, and when the molar ratio of the chloride ions in the saturated potassium chloride solution to the chloride ions in the hydrochloric acid solution is 20:1, both the crystallization rate of potassium chloride and the obtained potassium chloride crystal particles become small.

Test example 2

Potassium chloride crystal particles are extracted from the salt lake by the method for preparing potassium chloride from the salt lake. According to the existing salt lake production quality and crystal size, calculating according to the spherical shape to obtain the theoretical production particle number of the potassium chloride. The mass of the prepared potassium chloride crystal is calculated according to the spherical shape and multiplied by the corresponding number, and the theoretical production quality is calculated, as shown in table 3.

Wherein, the calculation formula

The calculation process is carried out in such a way that the ratio of the chloride ions of the saturated potassium chloride solution to the chloride ions of the hydrochloric acid solution is 15: 1.

Table 3 shows the annual yield of potassium chloride from salt lakes

As is clear from table 3, it is understood by calculation that the annual production amount of potassium chloride crystal grains is 100 million tons without adding the hydrochloric acid solution. The annual yield of the potassium chloride crystal particles is greatly improved after the hydrochloric acid solution is added, when the hydrochloric acid solution with the concentration of 5mol/L is added, the annual yield of the potassium chloride crystal particles reaches 583.34 ten thousand tons, and compared with the situation that the hydrochloric acid solution is not added, the yield is increased by 583.34%.

In summary, the embodiments of the present application provide a method for preparing potassium chloride from salt lake and a method for increasing the particle size of potassium chloride crystal particles, and the present application adds hydrochloric acid solution into saturated potassium chloride solution to increase Cl in the solution^-In an amount that allows the potassium chloride to crystallize out in a relatively rapid time and results in potassium chloride crystal particles of relatively large size. Therefore, potassium chloride crystal particles produced from the salt lake are large, the particle size of the potassium chloride crystal particles can reach 0.1-0.2 mm, and meanwhile, as the crystallization rate of potassium chloride is increased, more potassium chloride crystal particles can be obtained through crystallization in the same time, and further the yield is increased.

The foregoing is illustrative of the present application and is not to be construed as limiting thereof, as numerous modifications and variations will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.