Preparation method of potassium bicarbonate

Abstract

The invention discloses a preparation method of potassium bicarbonate, and belongs to the technical field of chemical raw material preparation. A preparation method of potassium bicarbonate comprises the following steps: mixing a water phase and an extraction agent, adding potassium chloride, uniformly mixing, introducing carbon dioxide gas, and stirring for reaction; crystallizing to obtain crystallized potassium bicarbonate and a mixed phase liquid, and standing the mixed phase liquid 1 for phase splitting; washing and separating the solid potassium bicarbonate with water, pre-melting the material with water, heating and cooking, and crystallizing a barren solution to obtain a finished product potassium bicarbonate; ammonium chloride is added into the ammonia water mother liquor to enable the mother liquor to be saturated, then the mother liquor is mixed with a solvent, liquid ammonia is introduced, the reaction is closed and stirred, crystallized solid ammonium chloride and mixed-phase liquid 2 are obtained, and the mixed-phase liquid 2 is subjected to standing layering; and adding ammonia mother liquor and the water pre-melting material into solid ammonium chloride, and concentrating and crystallizing the cooked solution to obtain the finished product ammonium chloride. The problems of low generation rate, high energy consumption, difficulty in solvent recovery and difficulty in application and popularization are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical raw material preparation, and particularly relates to a preparation method of potassium bicarbonate. Background Art

[0002] As an important chemical raw material, potassium bicarbonate plays a key role in industrial production. It is a potassium salt raw material used for the production of potassium carbonate and various downstream potassium salt products. In the food and pharmaceutical industries, although the usage amount is relatively small, due to its unique chemical properties and safety, it also has an indispensable application.

[0003] Currently, the production processes of potassium bicarbonate mainly include the ion exchange method and the method of electrolyzing potassium hydroxide and then carbonizing it with carbon dioxide. In the actual operation of the ion exchange method, a large amount of solution concentration is required. This step is not only complex in process but also consumes a huge amount of energy. Taking the common ion exchange method as an example, during the process of adsorbing and exchanging potassium ions, the solution needs to be concentrated. For every certain amount of product produced, the energy cost consumed occupies a quite large proportion in the total cost. When producing potassium bicarbonate through the electrolysis process, the consumption of electric energy is even more prominent. During the electrolysis process, a continuous and stable high-voltage current supply is required. Potassium chloride solution is electrolyzed to obtain potassium hydroxide, and then carbonized to obtain potassium bicarbonate. The large amount of electric energy consumption makes the production cost remain high, which undoubtedly greatly restricts the application of potassium bicarbonate in a wider range of fields and further market expansion.

[0004] In recent decades, the process of preparing potassium bicarbonate by solvent extraction has gradually come into the view of researchers, although only a small number of literatures have mentioned it. However, most of these studies are limited to basic aspects such as process principles, conversion rates, and conditions affecting the reaction. They mainly focus on theoretical exploration in the laboratory environment, and do not conduct a comprehensive and detailed demonstration of the entire process, nor propose a mature method suitable for large-scale industrial production. In industrial production, merely understanding the basic principles is far from enough. Many complex factors such as equipment selection, process flow optimization, production cost control, and product quality stability also need to be considered, and these aspects have not been fully explored and solved in previous studies.

[0005] Many countries have tried to promote the industrialization of this process, but in the actual process of promotion, they have encountered numerous obstacles. First of all, the difficult recovery of solvents is a thorny problem. The organic solvents used in the extraction process are difficult to recover and have low efficiency. Not only does it require a large amount of human, material and time costs, but the recovery effect is often not satisfactory. Secondly, the toxicity and safety issues of solvents have also greatly increased the difficulty of industrialization. Some organic solvents have strong toxicity and volatility. During the production, storage and transportation processes, they are likely to pose hazards to the health of operators, and there are also significant safety hazards. Once there is a leakage or accident, it may have a serious impact on the environment and surrounding residents. Moreover, the low conversion rate makes it difficult to achieve mass production. Due to the difficult precise control of reaction conditions, the production efficiency of potassium bicarbonate is low and cannot meet the requirements of large-scale industrial production. In addition, a large amount of energy is consumed during the solvent recovery process, further increasing the production cost. Also, the by-product calcium chloride generated during the reaction is difficult to handle. If it is discharged randomly, it will cause serious environmental pollution. If professional methods are used for treatment, it will bring additional economic costs and cause economic losses. These problems combined make the process of preparing potassium bicarbonate by solvent extraction face huge challenges in industrial promotion compared with the traditional ion exchange method and electrolysis method, and it is difficult to be widely applied in actual production. Summary of the Invention

[0006] The technical problem to be solved by the present invention is that the traditional method of preparation has problems such as low production rate, high energy consumption, difficult solvent recovery and difficult application and promotion. The purpose is to provide a method for preparing potassium bicarbonate, which solves the problems of low production rate, high energy consumption, difficult solvent recovery and difficult application and promotion.

[0007] The present invention is achieved by the following technical solutions:

[0008] A method for preparing potassium bicarbonate, comprising the following steps:

[0009] Mix the aqueous phase and the extractant, then add potassium chloride, mix evenly, introduce carbon dioxide gas, and start stirring and reacting in a closed space;

[0010] Obtain crystalline potassium bicarbonate and a mixed-phase liquid of aqueous phase and oil phase, and let the mixed-phase liquid 1 stand for phase separation;

[0011] The solid potassium bicarbonate is separated by washing with water to obtain crude potassium bicarbonate. The crude potassium bicarbonate is pre-treated with water, heated and cooked, and then crystallized from the lean liquid to obtain the finished potassium bicarbonate;

[0012] Add ammonium chloride to the ammonia mother liquor to saturate the mother liquor with ammonium chloride, then mix with the solvent, introduce liquid ammonia, react in a closed state, stir and react to obtain crystalline solid ammonium chloride and a mixed-phase liquid 2, and let the mixed-phase liquid 2 stand for layering;

[0013] Solid ammonium chloride is added to the ammonia mother liquor and water for pre-treatment, heated and cooked to remove ammonia and solvents, and the solution after cooking is concentrated and crystallized.

[0014] As a possible design, the above extractant includes alcohol, organic amine, kerosene and catalyst

[0015] As a possible design, the weight ratio of the above aqueous phase to the extractant is 1:(1 - 3).

[0016] As a possible design, the solid-liquid ratio of the above potassium chloride to the mixed solution of the aqueous phase and the extractant is (1 - 2):10.

[0017] As a possible design, the stirring speed of the above stirring reaction is 50 - 500 r / min, the reaction end point pressure is 0.01 - 0.5 MPa, the reaction temperature is 5 - 30 °C, and the reaction time is 10 - 60 min.

[0018] As a possible design, the above heating and cooking conditions are to dissolve the crude potassium bicarbonate in water at 80 °C - 130 °C, and dissolve the ammonium chloride in water at 60 °C - 130 °C.

[0019] As a possible design, the concentration of free amine in the above ammonia mother liquor is 1 - 25%.

[0020] As a possible design, the ratio of the aqueous phase to the organic phase for the back extraction of the above solid ammonium chloride obtained by crystallization is 1:(1 - 5).

[0021] As a possible design, the above stirring reaction conditions are a stirring speed of 50 - 500 revolutions per minute; a reaction temperature of 5 - 40 °C, the reaction end point is controlled at an ammonia gas introduction amount of 3% - 10% of the mass fraction of the extractant, and the reaction time is controlled at 10 - 60 min.

[0022] As a possible design, the ammonia and solvents removed by the above cooking are recovered and reused by spraying;

[0023] The above heating and cooking conditions are to dissolve the ammonium chloride in water at 60 °C - 130 °C.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] The present invention solves the energy consumption problem of traditional processes, solves the solvent recovery in solvent extraction, uses liquid ammonia for back extraction, and obtains high-quality ammonium chloride as a by-product. Ammonia and solvent are recovered in the system, and solid potassium bicarbonate and solid ammonium chloride are directly extracted, greatly reducing the concentration energy consumption. Moreover, a new extraction system is adopted, which greatly improves the single-pass conversion rate, making industrial production easier and more scalable. The solvent is completely recovered, and the product hardly contains any entrained solvent, making it more valuable in industrial economy. Through the treatment steps of the present invention, the single-pass output is greatly increased, as reflected in the chloride ion content in the organic phase reaching 1-2 mol / L. The solvent and extraction method of the present invention greatly improve the production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0027] Figure 1 is a flowchart of the present invention;

[0028] Figure 2 is a product diagram of step S3 of Example 1 of the present invention;

[0029] Figure 3 is a product diagram of step S5 of Example 1 of the present invention;

[0030] Figure 4 is a product diagram of step S3 of Example 2 of the present invention;

[0031] Figure 5 is a product diagram of step S5 of Example 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will further elaborate on the present invention in detail in combination with the embodiments and the drawings. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0033] A method for preparing potassium bicarbonate includes the following steps:

[0034] S1. Mix the aqueous phase and the extractant, then add potassium chloride, mix evenly, introduce carbon dioxide gas, and start stirring and reacting in a closed space to obtain a reaction solution.

[0035] The above extractant includes alcohol, organic amine, kerosene and catalyst.

[0036] The above alcohol can be but is not limited to n-octanol, the organic amine can be but is not limited to tri-n-octylamine, and the catalyst can be but is not limited to acetone.

[0037] In some embodiments of the present invention, the weight ratio of the above aqueous phase to the extractant is 1:(1 - 3).

[0038] In some embodiments of the present invention, the solid-liquid ratio of the above potassium chloride to the mixed solution of the aqueous phase and the extractant is (1 - 2):10.

[0039] Adding an excessive amount of potassium chloride will cause an increase in the chloride ions of the product, and a lower amount will cause a decrease in the single-pass conversion yield.

[0040] In some embodiments of the present invention, the stirring speed of the above stirring reaction is 50 - 500 r / min, the reaction key pressure is 0.01 - 0.5 MPa, the reaction temperature is 5 - 30 °C, and the reaction time is 10 - 60 min.

[0041] In some embodiments of the present invention, the above diluent includes kerosene and / or alcohols.

[0042] S2. Extract the reaction solution to obtain crystalline potassium bicarbonate and a mixed-phase liquid, and let the mixed-phase liquid 1 stand for phase separation.

[0043] The solid phase of the mixed-phase liquid 1 sinks to the bottom of the tank, the aqueous phase is in the middle, and the oil phase is on the top. It is separated manually or by an automatic instrument. The lower-layer solid phase and the aqueous phase are filtered to obtain solid potassium bicarbonate, the aqueous phase is recycled to the mother liquor tank, and the oil phase enters the back-extraction solvent tank.

[0044] In some embodiments of the present invention, the extractant used for the above extraction is n-octanol, tri-n-octylamine, kerosene and catalyst acetone

[0045] S3. The solid potassium bicarbonate is washed with water and separated to obtain crude potassium bicarbonate. The crude potassium bicarbonate is pre-treated with water, heated and cooked, and then crystallized from the lean liquid to obtain the finished potassium bicarbonate.

[0046] After the crude potassium bicarbonate is pre-treated with water and then heated and cooked, a small amount of ammonia and solvent can be removed. The lean liquid after ammonia evaporation enters the crystallizer for crystallization, thereby obtaining the finished potassium bicarbonate. The ammonia and solvent are recovered by spraying, and the ammonia and solvent can be completely recovered.

[0047] In some embodiments of the present invention, the above heating and cooking conditions are to dissolve the crude potassium bicarbonate in water at 80 °C - 130 °C, dissolve ammonium chloride in water at 60 °C - 130 °C, remove ammonia and solvent by heating, and spray and absorb the evaporated gas, so that the ammonia and solvent can be completely recovered.

[0048] S4. Add ammonium chloride to the ammonia mother liquor to saturate the mother liquor with ammonium chloride, then mix it with the solvent, introduce liquid ammonia, seal the reaction, stir the reaction to obtain crystalline solid ammonium chloride and the mixed-phase liquid 2, and let the mixed-phase liquid 2 stand for liquid separation.

[0049] The solvent (oil phase) in step S2 needs to be regenerated by back-extraction after extraction. Through the above treatment, the solvent is regenerated and continues to be used for extraction in step S2 after back-extraction regeneration.

[0050] The lower solid phase and the aqueous phase are filtered to obtain solid ammonium chloride. The aqueous phase is recycled to the mother liquor tank, and the oil phase enters the normal extraction solvent tank.

[0051] In some embodiments of the present invention, the concentration of the above ammonia mother liquor is 1-25%.

[0052] In some embodiments of the present invention, the ratio of the back-extraction aqueous phase to the organic phase for obtaining the crystalline solid ammonium chloride is 1:(1-5).

[0053] In some embodiments of the present invention, the stirring reaction conditions are as follows: the stirring speed is 50-500 revolutions per minute; the reaction temperature is 5-40°C, the reaction end point is controlled such that the liquid ammonia input amount is 3%-10% of the mass fraction of the extractant, and the reaction time is controlled within 10-60 min.

[0054] The above mixed-phase liquid 2 includes a liquid phase and an organic phase. To improve production efficiency, the unstratified mixed-phase liquid 2 is directly fed into a phase separation tank for operation, and left to stand for three-phase separation. The solid phase sinks to the bottom of the tank, the aqueous phase is in the middle, and the oil phase is on the top. Separation is carried out manually or by an automatic instrument.

[0055] S5. Add the solid ammonium chloride to the ammonia mother liquor and water for pre-conditioning, heat and cook to remove ammonia and the solvent, and concentrate and crystallize the cooked solution.

[0056] The ammonia and the solvent removed by the above cooking are recovered by spraying for reuse.

[0057] In some embodiments of the present invention, the above heating and cooking conditions are to dissolve ammonium chloride in water at 100°C - 130°C, remove ammonia and the solvent by heating, and spray and absorb the evaporated gas, so that ammonia and the solvent can be completely recovered.

[0058] Example 1

[0059] A method for preparing potassium bicarbonate, comprising the following steps:

[0060] S1. The forward and reverse extraction experiments were carried out in a 2L airtight stainless steel container. A saturated potassium mother liquor (saturated mother liquor of potassium chloride and potassium bicarbonate) was prepared, with the chloride ion content in the aqueous phase being 131.4 g / L. An extractant of n-octanol, tri-n-octylamine, kerosene and the catalyst acetone was prepared. The volume ratio of the extractant to the aqueous phase was 2:1. With the volume of the extractant being 1L, 0.5L of the mother liquor was added, and 80g of potassium chloride solid was added to the container. It was stirred airtight, and carbon dioxide gas was introduced. The reaction temperature was 5°C - 30°C, the extraction time was 30 min, and the pressure gauge showed a pressure of 0.1 Mpa.

[0061] S2. The reaction solution in step S1 was subjected to forward extraction. After the forward extraction was completed, it was placed in a funnel and left to stand. The phase separation time was recorded as 3 min 15 s, and the organic phase and the aqueous phase were completely clarified. The lower part of the potassium bicarbonate solid was separated, and the crude potassium bicarbonate was obtained by suction filtration. The mass of the crude potassium bicarbonate was weighed as 150.65 g. The chloride ion contents in the organic phase and the aqueous phase after extraction were measured. The chloride ion content in the aqueous phase was 128.5 g / L, and the chloride ion content in the organic phase was 40.48 g / L. Generally, the higher the chloride ion content in the organic phase, the better, as a higher content means higher extraction efficiency and higher yield.

[0062] S3. Water was added to the crude potassium bicarbonate, heated and dissolved, and continuously heated until there was no odor. The time was recorded as 10 min. After cooling and crystallization, the finished product of potassium bicarbonate was obtained. The product situation and indicators are as Figure 2 shown in Table 1.

[0063] S4. The reverse extraction experiment was carried out in a 2L airtight stainless steel container. A saturated ammonium chloride and concentrated ammonia water (saturated ammonium chloride solution prepared with concentrated ammonia water) was prepared, and the organic phase after forward extraction was added. The volume ratio of the organic phase to the aqueous phase was 3:1. With the volume of the organic phase being 1L, 0.33L of the mother liquor was added. It was stirred airtight, the reaction temperature was at room temperature, and the extraction time was 15 min. After the reverse extraction was completed, it was placed in a funnel and left to stand. The phase separation time was recorded as 3 min 45 s, and the organic phase and the aqueous phase were completely clarified. The lower part of the ammonium chloride solid was separated, and the crude ammonium chloride was obtained by suction filtration. The mass of the ammonium chloride was weighed as 58.32 g. The chloride ion content in the organic phase after extraction was measured. The chloride ion content in the organic phase was 0.1 g / L, and the reverse extraction was complete.

[0064] S5. Water was added to the crude ammonium chloride, heated and dissolved, and continuously heated until there was no odor. The time was recorded as 10 min. After cooling and crystallization, the finished product of ammonium chloride was obtained. The product situation and indicators are as Figure 3 shown in Table 2.

[0065] Table 1: Potassium bicarbonate

[0066]

[0067]

[0068] Table 2: Ammonium Chloride

[0069]

[0070] Example 2:

[0071] A method for preparing potassium bicarbonate, comprising the following steps:

[0072] S1. The forward and reverse extraction experiments are carried out in a 2L airtight stainless steel container. Prepare a saturated potassium mother liquor (saturated mother liquor of potassium chloride and potassium bicarbonate), with the chloride ion content in the aqueous phase being 134.8 g / L. Prepare an extractant of n-octanol, tri-n-octylamine, kerosene and a catalyst acetone. The volume ratio of the extractant to the aqueous phase is 3:1, and the volume of the solid of the extractant is 1L. Then add 0.33L of the mother liquor, add 70g of potassium chloride solid into the container, stir airtight, and introduce carbon dioxide gas. The reaction temperature is 5°C - 10°C, the extraction time is 30 min, and the pressure gauge shows a pressure of 0.1 Mpa.

[0073] S2. Carry out forward extraction on the reaction solution in step S1. After the forward extraction is completed, place it in a funnel and let it stand still. Record the phase separation time as 2 min 30 s, and the organic phase and the aqueous phase are completely clarified. Separate the lower part of the potassium bicarbonate solid, and obtain the crude potassium bicarbonate by suction filtration. Weigh the mass of the crude potassium bicarbonate as 132.25 g. Measure the chloride ion content in the organic phase and the aqueous phase after extraction. The chloride ion content in the aqueous phase is 133.5 g / L, and the chloride ion content in the organic phase is 34.62 g / L. Generally, the higher the chloride ion content in the organic phase, the better, which means the higher the extraction efficiency and the higher the yield.

[0074] S3. Add water to the crude potassium bicarbonate, heat and dissolve it, and continue heating until there is no smell. Record the time as 10 min, cool down and crystallize to obtain the finished product of potassium bicarbonate. The product situation and indicators are as Figure 4 , shown in Table 1.

[0075] S4. The reverse extraction experiment is carried out in a 2L airtight stainless steel container. Prepare a saturated ammonium chloride and concentrated ammonia water (prepare a saturated ammonium chloride solution with concentrated ammonia water), add the organic phase after forward extraction. The volume ratio of the organic phase to the aqueous phase is 4:1, and the volume of the organic phase is 1L. Then add 0.25L of the mother liquor, stir airtight, and the reaction temperature is room temperature, and the extraction time is 15 min. After the reverse extraction is completed, place it in a funnel and let it stand still. Record the phase separation time as 3 min 30 s, and the organic phase and the aqueous phase are completely clarified. Separate the lower part of the ammonium chloride solid, and obtain the crude ammonium chloride by suction filtration. Weigh the mass of the ammonium chloride as 51.32 g. Measure the chloride ion content in the organic phase after extraction. The chloride ion content in the organic phase is 0.1 g / L, and the reverse extraction is complete.

[0076] S5. Add water to the crude ammonium chloride, heat to dissolve it, and continue heating until there is no odor. Record the time as 10 minutes, and then cool down to crystallize to obtain the ammonium chloride product. The product situation and indicators are as Figure 5 , shown in Table 2.

[0077] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing potassium bicarbonate, characterized in that, The steps include: The aqueous phase and the extractant are mixed, potassium chloride is added, the mixture is evenly mixed, carbon dioxide gas is introduced, and the stirring reaction is started in a closed space; Crystallized potassium bicarbonate and a mixed phase liquid are obtained, and the mixed phase liquid 1 is allowed to stand for phase separation; Solid potassium bicarbonate is washed and separated with water to obtain crude potassium bicarbonate, and the crude potassium bicarbonate is pre-treated with water, heated and boiled, and then crystallized to obtain finished potassium bicarbonate; Add ammonium chloride to the ammonia mother liquor to saturate the mother liquor with ammonium chloride, mix it with the solvent, introduce liquid ammonia, close the reaction chamber, stir the reaction, and obtain crystalline solid ammonium chloride and a mixed phase liquid 2, and let the mixed phase liquid 2 stand for stratification; Solid ammonium chloride is added to ammonia mother liquor and water to pre-cook the material, heated and boiled to remove ammonia and solvent, and the boiled solution is concentrated and crystallized.

2. A method for preparing potassium bicarbonate according to claim 1, characterized in that, The extractant comprises alcohol, organic amine, kerosene and a catalyst.

3. A method for preparing potassium bicarbonate according to claim 1, characterized in that, The volume ratio of aqueous phase to extractant is 1:(1-3).

4. A method for preparing potassium bicarbonate according to claim 1, characterized in that, The solid-to-liquid ratio of the potassium chloride to the mixed solution of the aqueous phase and the extractant is (1-2):

10.

5. A method for preparing potassium bicarbonate according to claim 1, characterized in that, The stirring speed of the stirring reaction is 50-500 r / min, the reaction pressure is 0.01-0.5 MPa, the reaction temperature is 5-30° C., and the reaction time is 10-60 min.

6. A method for preparing potassium bicarbonate according to claim 1, characterized in that, The heating and cooking conditions are as follows: the crude potassium bicarbonate is dissolved in water at 80° C.-130° C., and the ammonium chloride is dissolved in water at 60° C.-130° C.

7. A method for preparing potassium bicarbonate according to claim 1, characterized in that, The free ammonia concentration of the ammonia mother liquor is 1-25%.

8. A method for preparing potassium bicarbonate according to claim 1, characterized in that, The ratio of the aqueous phase to the organic phase of the solvent in the back extraction of the crystalline solid ammonium chloride is 1:(1-5).

9. A method for preparing potassium bicarbonate according to claim 1, characterized in that, The stirring reaction conditions are stirring speed of 50-500 rpm, reaction temperature of 5-40°C, reaction end point controlled at liquid ammonia introduction amount of 3%-10% of the mass fraction of the extractant, and reaction time controlled at 10-60min.

10. A method for preparing potassium bicarbonate according to claim 1, characterized in that: The ammonia and solvent removed by the cooking are recycled and reused through spraying; The heating and steaming conditions are as follows: dissolving ammonium chloride in water at 60° C.-130° C.

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