阅读说明：本技术 一种脱色氯化钾溶液的制备方法 (Preparation method of decolored potassium chloride solution ) 是由 徐毅 冷鹏 曹国华 于 2020-05-13 设计创作，主要内容包括：为解决现有技术中氯化钾溶液脱色效果不佳的问题,本发明提供了一种脱色氯化钾溶液的制备方法,包括以下操作步骤：氯化钾盐渣原料进行加热处理,得到氯化钾盐渣中间体,将氯化钾盐渣中间体溶解于溶剂中,得到氯化钾溶液,再向氯化钾溶液中加入氧化剂以及吸附剂,分离吸附剂,得到脱色氯化钾溶液,其中,吸附剂包括活性炭和聚丙烯酰胺,活性炭采用硝酸活化处理。在本发明提供的脱色氯化钾溶液的制备方法中,脱色性能良好,生产工艺和使用简便,脱色效果稳定以及适合大规模生产。(In order to solve the problem of poor decolorizing effect of potassium chloride solution in the prior art, the invention provides a preparation method of decolorized potassium chloride solution, which comprises the following operation steps: heating a potassium chloride salt slag raw material to obtain a potassium chloride salt slag intermediate, dissolving the potassium chloride salt slag intermediate in a solvent to obtain a potassium chloride solution, adding an oxidant and an adsorbent into the potassium chloride solution, and separating the adsorbent to obtain a decolored potassium chloride solution, wherein the adsorbent comprises activated carbon and polyacrylamide, and the activated carbon is subjected to nitric acid activation treatment. In the preparation method of the decolored potassium chloride solution provided by the invention, the decoloration performance is good, the production process and the use are simple and convenient, the decoloration effect is stable, and the method is suitable for large-scale production.)

1. The preparation method of the decolored potassium chloride solution is characterized by comprising the following operation steps:

heating the potassium chloride slag raw material to obtain a potassium chloride slag intermediate;

dissolving the potassium chloride salt residue intermediate in a solvent to obtain a potassium chloride solution;

adding an oxidant to the potassium chloride solution;

adding an adsorbent into the potassium chloride solution, and separating the adsorbent to obtain a decolored potassium chloride solution;

the adsorbent comprises activated carbon and polyacrylamide, and the activated carbon is activated by nitric acid.

2. The method for preparing a decolorized potassium chloride solution according to claim 1, wherein the mass ratio of the activated carbon to the polyacrylamide in the adsorbent is (9.5-9.9): (0.1-0.5).

3. The method for preparing a decolorized potassium chloride solution according to claim 1, wherein the nitric acid activation treatment includes:

controlling the pH value of nitric acid to be less than 3, and completely immersing the activated carbon in the nitric acid;

separating the activated carbon from the nitric acid, spraying the activated carbon, and drying to obtain the nitric acid activated carbon.

4. The method for preparing a decolorized potassium chloride solution according to claim 1, characterized in that an alkaline assistant is added to a potassium chloride slag raw material before or while the heating treatment is performed, and the mass ratio of the potassium chloride slag raw material to the alkaline assistant is (9.0-9.5): 0.5-1.0;

the alkaline auxiliary agent comprises KOH and Ca (OH)₂One or two of them.

5. The method for preparing a decolorized potassium chloride solution according to claim 1, wherein the temperature of the heat treatment is 120 to 200 ℃.

6. The method for preparing the decolored potassium chloride solution according to claim 1, wherein the solvent is selected from water, and the mass ratio of the solvent to the potassium chloride salt residue intermediate is 2: 1-4: 1.

7. The method for preparing a decolorized potassium chloride solution according to claim 1, wherein the oxidizing agent comprises hydrogen peroxide and/or sodium hypochlorite, and the amount of the oxidizing agent added is 2% to 8% based on 100% by mass of the potassium chloride solution.

8. The method for preparing a decolorized potassium chloride solution according to claim 1, wherein the adsorbent is added in an amount of 1% to 3% based on 100% by mass of the total potassium chloride solution.

9. The method for preparing a decolorized potassium chloride solution according to claim 1, wherein the potassium chloride slag raw material includes potassium chloride, carbon-containing organic substances, and potassium fluoride.

10. The method for preparing a decolorized potassium chloride solution according to claim 9, further comprising, before the "adding an adsorbent to the potassium chloride solution":

adding a calcium salt to the potassium chloride solution.

Technical Field

The invention belongs to the field of waste salt resource recycling, and particularly relates to a preparation method of a decolored potassium chloride solution.

Background

Potassium chloride is a versatile inorganic salt. Potassium chloride is mainly used in the inorganic industry and is a basic raw material for manufacturing various potassium salts or alkalis such as potassium hydroxide, potassium sulfate, potassium nitrate, potassium chlorate, potassium bichromate and the like. In the pharmaceutical industry, it is used as diuretic and potassium deficiency preventing medicine.

In some organic or inorganic chemical production processes, potassium chloride waste salt is often generated, contains a large amount of organic or inorganic impurities, cannot be directly used as industrial raw material salt, and has a great threat to the environment, the salt and the impurities are extremely easy to run off, the surrounding soil is salinized, surrounding vegetation is endangered, and surrounding rivers, water sources, rice fields and the like are polluted. Therefore, the high-purity potassium chloride can be obtained only by the steps of removing impurities, oxidizing, decoloring and the like of the waste potassium chloride salt.

At present, the decolorizing technology for treating the potassium chloride waste salt mainly comprises the following steps: adsorption decoloration, coagulation decoloration, oxidation decoloration, electrolysis decoloration, biological decoloration, flocculation decoloration and the like. However, the components of the potassium chloride solution are complex and variable, only one decolorizing technology is used, the requirement of decolorizing treatment of the potassium chloride solution cannot be met, and how to improve the decolorizing and impurity removing effects of the potassium chloride waste salt is a problem to be solved in the field.

Disclosure of Invention

Aiming at the problem of poor decolorizing effect of potassium chloride solution in the prior art, the invention provides a preparation method of decolorized potassium chloride solution.

The technical scheme adopted by the invention for solving the problems is as follows:

the invention provides a preparation method of a decolored potassium chloride solution, which comprises the following operation steps:

heating the potassium chloride slag raw material to obtain a potassium chloride slag intermediate;

dissolving the potassium chloride salt residue intermediate in a solvent to obtain a potassium chloride solution;

adding an oxidant to the potassium chloride solution;

adding an adsorbent into the potassium chloride solution, and separating the adsorbent to obtain a decolored potassium chloride solution;

the adsorbent comprises activated carbon and polyacrylamide, and the activated carbon is activated by nitric acid.

Optionally, in the adsorbent, the mass ratio of the activated carbon to the polyacrylamide is (9.5-9.9): (0.1-0.5).

Alternatively, the nitric acid activation treatment comprises:

controlling the pH value of nitric acid to be less than 3, and completely immersing the activated carbon in the nitric acid;

separating the activated carbon from the nitric acid, spraying the activated carbon, and drying to obtain the nitric acid activated carbon.

Optionally, before or during the heating treatment, adding an alkaline assistant into the potassium chloride salt slag raw material, wherein the mass ratio of the potassium chloride salt slag raw material to the alkaline assistant is (9.0-9.5): (0.5-1.0).

Optionally, the basic auxiliary agent comprises KOH and Ca (OH)₂One or two of them.

Optionally, the temperature of the heating treatment is 120-200 ℃.

Optionally, the solvent is selected from water, and the mass ratio of the solvent to the potassium chloride salt residue intermediate is 2: 1-4: 1.

Optionally, the oxidant comprises hydrogen peroxide and/or sodium hypochlorite, and the addition amount of the oxidant is 2-8% based on 100% of the total mass of the potassium chloride solution.

Optionally, the addition amount of the adsorbent is 1% to 3% based on 100% of the total mass of the potassium chloride solution.

Optionally, the potassium chloride slag raw material comprises potassium chloride, carbon-containing organic matter and potassium fluoride.

Optionally, before the "adding an adsorbent to the potassium chloride solution", further comprising:

adding a calcium salt to the potassium chloride solution.

The invention adopts polyacrylamide and nitric acid activated carbon as the adsorbent to treat the potassium chloride solution, and the inventor finds that the polyacrylamide and the nitric acid activated carbon have obvious synergistic effect, and compared with a single component, the adsorbent formed by compounding two substances can show more excellent adsorption performance under the condition of the same addition amount, so that the use amount of the adsorbent can be reduced while the removal efficiency of organic pigments and other impurities in the potassium chloride solution is improved, and the invention has the advantages of favorable decoloration performance, low production process cost, simple and convenient use and stable decoloration effect, and is suitable for large-scale production.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects solved by the present invention more apparent, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides a preparation method of a decolored potassium chloride solution, which comprises the following operation steps:

heating the potassium chloride slag raw material to obtain a potassium chloride slag intermediate;

dissolving the potassium chloride salt residue intermediate in a solvent to obtain a potassium chloride solution;

adding an oxidant to the potassium chloride solution;

adding an adsorbent into the potassium chloride solution, and separating the adsorbent to obtain a decolored potassium chloride solution;

the adsorbent comprises activated carbon and polyacrylamide, and the activated carbon is activated by nitric acid.

The invention adopts polyacrylamide and nitric acid activated carbon as the adsorbent to treat the potassium chloride solution, and the inventor finds that the polyacrylamide and the nitric acid activated carbon have obvious synergistic effect, and compared with a single component, the adsorbent formed by compounding two substances can show more excellent adsorption performance under the condition of the same addition amount, so that the use amount of the adsorbent can be reduced while the removal efficiency of organic pigments and other impurities in the potassium chloride solution is improved, and the invention has the advantages of favorable decoloration performance, low production process cost, simple and convenient use and stable decoloration effect, and is suitable for large-scale production.

The activated carbon is activated with nitric acid to increase the specific surface area of the activated carbon, thereby increasing the adsorption effect.

In some embodiments of the invention, the mass ratio of the activated carbon to the polyacrylamide in the adsorbent is (9.5-9.9): (0.1-0.5).

Compared with the single adsorbent, the nitric acid activated carbon and polyacrylamide are better in adsorption and decoloration effects, have stronger flocculation adhesion and trapping effects on fine particle impurities in a potassium chloride solution, are lower in combined use amount and are clearer. If the ratio of polyacrylamide in the adsorbent is too high, the potassium chloride solution is too viscous, and the amount of waste residues generated is too large, which in turn deteriorates the decoloring effect of the present invention. In the adsorbent, if the ratio of the activated carbon is too high, namely the usage amount of the polyacrylamide is too small, the decolorizing effect of the invention is not obvious.

In some embodiments of the invention, the nitric acid activation treatment comprises:

controlling the pH value of nitric acid to be less than 3, and completely immersing the activated carbon in the nitric acid;

separating the activated carbon from the nitric acid, spraying the activated carbon, and drying to obtain the nitric acid activated carbon.

More preferably, controlling the pH value of nitric acid to be less than 3, completely immersing the activated carbon in the nitric acid, and stirring for 1h at the temperature of 75-85 ℃;

and cooling, centrifugally separating the activated carbon from the nitric acid, spraying the activated carbon with pure water, and drying to obtain the nitric acid activated carbon.

The activated carbon with larger specific surface area and more uniform pore size distribution is obtained by controlling the pH value of the nitric acid, preserving heat, stirring, cooling, centrifuging and spraying and cleaning the activated carbon.

In some embodiments of the invention, before or simultaneously with the heating treatment, an alkaline assistant is added into the potassium chloride salt slag raw material, and the mass ratio of the potassium chloride salt slag raw material to the alkaline assistant is (9.0-9.5): (0.5-1.0).

In the invention, organic matters with chromaticity in the potassium chloride salt slag raw material are evaporated or carbonized and polymerized by using a heating method, and the carbonic ester polymer and other carbon-containing organic matters can be promoted to be carbonized and decomposed by using the alkaline auxiliary agent, so that the removal efficiency of the carbon-containing organic matters in the subsequent operation is improved, and the intermediate of the potassium chloride salt slag is obtained quickly.

In some embodiments of the invention, the basic additive comprises KOH and Ca (OH)₂One or two of them.

In a preferred embodiment, the alkaline builder is selected from potassium hydroxide, which is advantageous in avoiding the introduction of impurity elements in subsequent operations.

In some embodiments of the present invention, the temperature of the heat treatment is 120 to 200 ℃.

If the temperature of the heating treatment is more than 200 ℃, a large amount of heat and gas can be generated, and the safety of experimental equipment is threatened. The heating treatment temperature is lower than 120 ℃, and the effect of decomposing impurity organic matters in the potassium chloride slag raw material by heating treatment is not obvious.

More preferably, the temperature of the heating treatment is controlled within the range of 150-160 ℃.

In some embodiments of the invention, the solvent is selected from water, and the mass ratio of the solvent to the potassium chloride salt residue intermediate is 2: 1-4: 1.

More preferably, the mass ratio of the solvent to the potassium chloride salt slag intermediate is 3: 1-4: 1.

In some embodiments of the invention, the oxidizing agent comprises hydrogen peroxide and/or sodium hypochlorite, and the amount of the oxidizing agent is 2-8% based on 100% of the total mass of the potassium chloride solution.

More preferably, the amount of the oxidizing agent is 2% to 5% based on 100% by mass of the total potassium chloride solution.

The hydrogen peroxide or the sodium hypochlorite is used as the oxidant, and the hydrogen peroxide and the sodium hypochlorite are strong oxidants, so that organic matters subjected to carbonization decomposition and carbonization polymerization can be oxidized, and the decoloring effect is improved.

In some embodiments of the invention, the adsorbent is added in an amount of 1% to 3% based on 100% of the total mass of the potassium chloride solution.

More preferably, the adsorbent is added in an amount of 1% to 3% based on 100% by mass of the total potassium chloride solution.

In some embodiments of the invention, the potassium chloride slag feedstock comprises potassium chloride, a carbon-containing organic, and potassium fluoride.

The carbon-containing organic includes a carbonate polymer.

Because fluoride ions are contained in the potassium chloride slag raw material, before the step of adding the adsorbent into the potassium chloride solution, the method further comprises the following steps:

adding calcium salt into the potassium chloride solution, and combining fluoride ions with calcium ions for precipitation. The formed precipitate can be separated in the subsequent operation of separating the adsorbent, thereby effectively reducing impurity ions in the potassium chloride solution.

In some embodiments of the invention, the potassium chloride salt residue intermediate is dissolved in a solvent, an oxidant is added into a potassium chloride solution, an adsorbent is added into the potassium chloride solution, and the adsorbent is removed by stirring and filtering, wherein the stirring time is 1-4 hours.

More preferably, the stirring time is 1-2 h.

The present invention will be further illustrated by the following examples. It is to be understood that the present invention is not limited to the following embodiments, and methods are regarded as conventional methods unless otherwise specified. Materials are commercially available from the open literature unless otherwise specified.

Example 1

This example illustrates the preparation of a decolorized potassium chloride solution according to the present disclosure.

The potassium chloride solution is prepared by the following material components:

(1) potassium chloride slag raw material 200g

(2) 800g of tap water

(3) 50g of hydrogen peroxide

(4) 10g of adsorbent (the adsorbent comprises powdered activated carbon and polyacrylamide powder, and the activated carbon is activated by nitric acid)

The preparation method comprises the following steps:

(1) according to the components, putting a potassium chloride salt slag raw material into a muffle furnace, baking at 150 ℃ for 24 hours, and taking out to obtain a potassium chloride salt slag intermediate;

(2) adding tap water into the potassium chloride salt slag intermediate obtained in the step (1) according to the components to obtain a black turbid potassium chloride solution, and stirring until the black turbid potassium chloride solution is fully dissolved;

(3) adding hydrogen peroxide according to the components, and stirring for 1 h;

(4) the adsorbent was added to the above components, stirred for 1h and filtered to obtain a decolorized potassium chloride solution, labeled S1.

Example 2

This example illustrates the preparation of a decolorized potassium chloride solution according to the present disclosure.

The potassium chloride solution is prepared by the following material components:

(1) potassium chloride slag raw material 200g

(2) 800g of tap water

(3) Sodium hypochlorite 50g

(4) 10g of adsorbent (the adsorbent comprises powdered activated carbon and polyacrylamide powder, and the activated carbon is activated by nitric acid)

The preparation method comprises the following steps:

(1) according to the components, putting a potassium chloride salt slag raw material into a muffle furnace, baking at 150 ℃ for 24 hours, and taking out to obtain a potassium chloride salt slag intermediate;

(2) adding tap water into the step (1) according to the components to obtain a black turbid potassium chloride solution, and stirring until the black turbid potassium chloride solution is fully dissolved;

(3) adding sodium hypochlorite into the components and stirring for 1 hour;

(4) the adsorbent was added to the above components, stirred for 1h and filtered to obtain a decolorized potassium chloride solution, labeled S2.

Example 3

This example illustrates the preparation of a decolorized potassium chloride solution according to the present disclosure.

The potassium chloride solution is prepared by the following material components:

(1) potassium chloride slag raw material 200g

(2) 800g of tap water

(3) 50g of hydrogen peroxide

(4) 10g of adsorbent (the adsorbent comprises powdered activated carbon and polyacrylamide powder, and the activated carbon is activated by nitric acid)

The preparation method comprises the following steps:

(1) according to the components, putting a potassium chloride salt slag raw material into a muffle furnace, baking at 160 ℃ for 24 hours, and taking out to obtain a potassium chloride salt slag intermediate;

(2) adding tap water into the step (1) according to the components to obtain a black turbid potassium chloride solution, and stirring until the black turbid potassium chloride solution is fully dissolved;

(3) adding hydrogen peroxide according to the components, and stirring for 1 h;

(4) the adsorbent was added to the above components, stirred for 1h and filtered to obtain a decolorized potassium chloride solution, labeled S3.

Example 4

This example illustrates the preparation of a decolorized potassium chloride solution according to the present disclosure.

The potassium chloride solution is prepared by the following material components:

(1) potassium chloride slag raw material 200g

(2) 800g of tap water

(3) 20g of hydrogen peroxide

(4) 10g of adsorbent (the adsorbent comprises powdered activated carbon and polyacrylamide powder, and the activated carbon is activated by nitric acid)

The preparation method comprises the following steps:

(1) according to the components, putting a potassium chloride salt slag raw material into a muffle furnace, baking at 150 ℃ for 24 hours, and taking out to obtain a potassium chloride salt slag intermediate;

(2) adding tap water into the step (1) according to the components to obtain a black turbid potassium chloride solution, and stirring until the black turbid potassium chloride solution is fully dissolved;

(3) adding hydrogen peroxide according to the components, and stirring for 1 h;

(4) the adsorbent was added to the above components, stirred for 1h and filtered to obtain a decolorized potassium chloride solution, labeled S4.

Example 5

This example illustrates the preparation of a decolorized potassium chloride solution according to the present disclosure.

The potassium chloride solution is prepared by the following material components:

(1) potassium chloride slag raw material 200g

(2) 800g of tap water

(3) 50g of hydrogen peroxide

(4) 20g of adsorbent (the adsorbent comprises powdered activated carbon and polyacrylamide powder, and the activated carbon is activated by nitric acid)

The preparation method comprises the following steps:

(1) according to the components, putting a potassium chloride salt slag raw material into a muffle furnace, baking at 150 ℃ for 24 hours, and taking out to obtain a potassium chloride salt slag intermediate;

(2) adding tap water into the step (1) according to the components to obtain a black turbid potassium chloride solution, and stirring until the black turbid potassium chloride solution is fully dissolved;

(3) adding hydrogen peroxide according to the components, and stirring for 1 h;

(4) the adsorbent was added to the above components, stirred for 1h and filtered to obtain a decolorized potassium chloride solution, labeled S5.

Example 6

This example illustrates the preparation of a decolorized potassium chloride solution according to the present disclosure.

The potassium chloride solution is prepared by the following material components:

(1) potassium chloride slag raw material 200g

(2) 800g of tap water

(3) 50g of hydrogen peroxide

(4) 20g of adsorbent (the adsorbent comprises powdered activated carbon and polyacrylamide powder, and the activated carbon is activated by nitric acid)

The preparation method comprises the following steps:

(1) according to the components, putting a potassium chloride salt slag raw material into a muffle furnace, baking at 150 ℃ for 24 hours, and taking out to obtain a potassium chloride salt slag intermediate;

(2) adding tap water into the step (1) according to the components to obtain a black turbid potassium chloride solution, and stirring until the black turbid potassium chloride solution is fully dissolved;

(3) adding hydrogen peroxide according to the components, and stirring for 2 hours;

(4) the adsorbent is added according to the components, stirred for 2h and filtered to obtain a decolorized potassium chloride solution, which is marked as S6.

Example 7

This example illustrates the preparation of a decolorized potassium chloride solution according to the present disclosure.

The potassium chloride solution is prepared by the following material components:

(1) potassium chloride slag raw material 200g

(2) 10g of potassium hydroxide

(2) 800g of tap water

(3) 50g of hydrogen peroxide

(4) 10g of adsorbent (the adsorbent comprises powdered activated carbon and polyacrylamide powder, and the activated carbon is activated by nitric acid)

The preparation method comprises the following steps:

(1) according to the components, potassium chloride salt slag raw materials are added with potassium hydroxide and mixed, the mixture is placed in a muffle furnace and baked for 24 hours at 150 ℃, and then taken out to obtain a potassium chloride salt slag intermediate;

(2) adding tap water into the potassium chloride salt slag intermediate obtained in the step (1) according to the components to obtain a black turbid potassium chloride solution, and stirring until the black turbid potassium chloride solution is fully dissolved;

(3) adding hydrogen peroxide according to the components, and stirring for 1 h;

(4) the adsorbent was added to the above components, stirred for 1h and filtered to obtain a decolorized potassium chloride solution, labeled S7.

Example 8

This example illustrates the preparation of a decolorized potassium chloride solution according to the present disclosure.

The potassium chloride solution is prepared by the following material components:

(1) potassium chloride slag raw material 200g

(2) 20g of anhydrous calcium chloride

(3) 800g of tap water

(4) 50g of hydrogen peroxide

(5) 10g of adsorbent (the adsorbent comprises powdered activated carbon and polyacrylamide powder, and the activated carbon is activated by nitric acid)

The preparation method comprises the following steps:

(1) according to the components, putting a potassium chloride salt slag raw material into a muffle furnace, baking at 150 ℃ for 24h, and taking out to obtain a potassium chloride salt slag intermediate;

(2) adding tap water into the potassium chloride salt slag intermediate obtained in the step (1) according to the components to obtain a black turbid potassium chloride solution, and stirring until the black turbid potassium chloride solution is fully dissolved;

(3) adding calcium chloride into the potassium chloride solution, and stirring for 1 h;

(4) adding hydrogen peroxide according to the components, and stirring for 1 h;

(5) the adsorbent was added to the above components, stirred for 1h and filtered to obtain a decolorized potassium chloride solution, labeled S8.

Comparative example 1

This example is intended to illustrate by way of comparison the preparation of a decolorized potassium chloride solution according to the present disclosure.

The comparative preparation of potassium chloride solution comprises the following material components:

(1) potassium chloride slag raw material 200g

(2) 800g of tap water

(3) 50g of hydrogen peroxide

(4) 10g of adsorbent (powdered activated carbon, activated carbon by nitric acid treatment)

The preparation method comprises the following steps:

(1) according to the components, taking a potassium chloride salt slag raw material, baking the potassium chloride salt slag raw material in a muffle furnace at 150 ℃ for 24 hours, and taking out the potassium chloride salt slag raw material to obtain a potassium chloride salt slag intermediate;

(2) adding tap water into the step (1) according to the components to obtain a black turbid potassium chloride solution, and stirring until the black turbid potassium chloride solution is fully dissolved;

(3) adding hydrogen peroxide according to the components, and stirring for 1 h;

(4) the adsorbent was added as above, stirred for 1h and filtered to give a comparative potassium chloride solution, labelled D1.

Comparative example 2

This example is intended to illustrate by way of comparison the preparation of a decolorized potassium chloride solution according to the present disclosure.

The comparative preparation of potassium chloride solution comprises the following material components:

(1) potassium chloride slag raw material 200g

(2) 800g of tap water

(3) 50g of hydrogen peroxide

(4) Adsorbent (Polyacrylamide) 10g

The preparation method comprises the following steps:

(1) according to the components, taking a potassium chloride salt slag raw material, baking the potassium chloride salt slag raw material in a muffle furnace at 150 ℃ for 24 hours, and taking out the potassium chloride salt slag raw material to obtain a potassium chloride salt slag intermediate;

(2) adding tap water into the step (1) according to the components to obtain a black turbid potassium chloride solution, and stirring until the black turbid potassium chloride solution is fully dissolved;

(3) adding hydrogen peroxide according to the components, and stirring for 1 h;

(4) the adsorbent was added as above, stirred for 1h and filtered to give a comparative potassium chloride solution, labelled D2.

Comparative example 3

This example is intended to illustrate by way of comparison the preparation of a decolorized potassium chloride solution according to the present disclosure.

The comparative preparation of potassium chloride solution comprises the following material components:

(1) potassium chloride slag raw material 200g

(2) 800g of tap water

(3) 50g of hydrogen peroxide

(4) 10g of adsorbent (the adsorbent comprises powdered activated carbon and polyacrylamide powder, and the activated carbon is not subjected to nitric acid activation treatment)

The preparation method comprises the following steps:

(1) according to the components, taking a potassium chloride salt slag raw material, baking the potassium chloride salt slag raw material in a muffle furnace at 150 ℃ for 24 hours, and taking out the potassium chloride salt slag raw material to obtain a potassium chloride salt slag intermediate;

(2) adding tap water into the step (1) according to the components to obtain a black turbid potassium chloride solution, and stirring until the black turbid potassium chloride solution is fully dissolved;

(3) adding hydrogen peroxide according to the components, and stirring for 1 h;

(4) the adsorbent was added as above, stirred for 1h and filtered to give a comparative potassium chloride solution, labelled D3.

Evaluation of Performance

Colorimetric test

And respectively taking potassium chloride solutions S1-S8 and the compared potassium chloride solutions D1-D3 and a standard sample colorimetric tube for color comparison, and detecting the content of fluoride ions in the potassium chloride solution by adopting a chemical titration method.

The results of the tests are shown in table 1.

TABLE 1

Numbering	Chroma (Hazen)	Fluoride ion content (mg/L)
			S1	Light color transparent (30-35)	1500
S2	Light yellow transparent (45-50)	1460
			S3	Light color transparent (20-25)	1490
S4	Light yellow transparent (45-50)	1530
			S5	Light color transparent (20-25)	1520
S6	Light color transparent (20-25)	1410
			S7	Light color transparent (15-20)	1470
S8	Light color transparent (30-35)	0.15
			D1	Yellow with turbidity (155-	1505
D2	Black and red color	1450
			D3	Deep yellow transparent (250-255)	1490

As can be seen from Table 1, the potassium chloride solutions obtained in examples S1 to S8 have higher transparency than those obtained in comparative examples D1 to D3, which indicates that the activated carbon activated by polyacrylamide and nitric acid composite is used as an adsorbent, so that the decolorization effect is better, and pigments or other organic impurities in the potassium chloride solution can be more effectively removed.

The test results of the comparative example 7 and the example 1 show that the addition of the alkaline assistant in the heating treatment process can effectively promote the decomposition of organic impurities in the potassium chloride salt slag raw material, and further reduce the impurity content in the decolored potassium chloride solution.

The test results of comparative example 8 and example 1 show that the addition of calcium salt to the potassium chloride solution can promote the precipitation of fluoride ions therein, and effectively reduce the content of impurity ions in the potassium chloride solution.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.