A process for recovering potassium dihydrogen phosphate, potassium chloride and inositol from a potassium dihydrogen phosphate mother liquor

Abstract

The present application relates to the technical field of corn soaking water treatment, and particularly relates to a process method for recovering potassium dihydrogen phosphate, potassium chloride and inositol from potassium dihydrogen phosphate mother liquor, which comprises the following contents: the collected potassium dihydrogen phosphate mother liquor is first treated by a simulated moving bed chromatographic separation system, the collected inositol phase is concentrated, crystallized and filtered, the collected first filter cake is heated and added with water, decolorized and filtered, the collected second filtrate is cooled, crystallized, filtered and eluted, and the collected filter cake is dried; the collected salt phase is adjusted in pH, concentrated, cooled and crystallized, and filtered, the collected third filter cake is dried to obtain potassium dihydrogen phosphate product, and the collected third filtrate is concentrated and filtered, and the collected fourth filter cake is dried to obtain potassium chloride product; the process method greatly improves the yield and purity of the inositol product, and also obtains high-yield and high-yield potassium dihydrogen phosphate product and potassium chloride product.

Description

Technical Field

[0001] This invention relates to the field of corn soaking water treatment technology, and in particular to a process for recovering potassium dihydrogen phosphate, potassium chloride and inositol from potassium dihydrogen phosphate mother liquor. Background Technology

[0002] Corn soaking water is a byproduct of wet corn starch production, containing 1-2% phytic acid. Currently, there are reported methods for recovering phytic acid from corn soaking water to prepare potassium phytate, followed by hydrolysis, separation, concentration, and crystallization to produce inositol and potassium dihydrogen phosphate. Compared to traditional potassium dihydrogen phosphate production processes such as neutralization and metathesis, using corn soaking water as a raw material not only avoids the environmental damage caused by phosphate rock mining but also achieves the recycling of phosphorus resources from plants, resulting in significant economic and social benefits.

[0003] Current processes typically separate potassium dihydrogen phosphate (KH2PO4) and inositol obtained from corn soaking water using simulated moving bed chromatography. This separation yields KH2PO4 and inositol solutions. However, both inositol and KH2PO4 are readily soluble in water. In actual production, limitations imposed by chromatographic resin separation and process parameters mean that the resulting KH2PO4 solution usually contains a certain concentration of inositol. During KH2PO4 crystallization, inositol, pigments, proteins, calcium and magnesium, chloride ions, and other substances gradually accumulate in the mother liquor, eventually reaching a KH2PO4 concentration of 25-45 g / L. Currently, the KH2PO4 crystallization mother liquor is mostly sold directly as liquid fertilizer, resulting in significant underutilization of its inositol value and substantial losses.

[0004] Existing patents disclose a process for recovering inositol from potassium dihydrogen phosphate mother liquor. While this process can recover inositol from the mother liquor, small molecule salts are not separated from inositol during crude product crystallization, resulting in a low inositol yield. Furthermore, the phosphate and potassium ions in the mother liquor are not fully recovered. Therefore, to address these issues, it is necessary to develop a process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a process for recovering potassium dihydrogen phosphate, potassium chloride and inositol from potassium dihydrogen phosphate mother liquor, which can obtain a high yield of inositol product, and can also obtain potassium dihydrogen phosphate and potassium chloride products.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] A process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor includes the following steps:

[0008] (1) The collected potassium dihydrogen phosphate crystallization mother liquor was processed using a simulated moving bed chromatography separation system, and the inositol phase and salt phase were collected separately;

[0009] (2) Take the inositol phase described in step (1), concentrate, cool and crystallize, filter and wash, and collect the first filter cake and the first filtrate respectively. The first filtrate is combined with the potassium dihydrogen phosphate mother liquor.

[0010] (3) Take the first filter cake from step (2), add purified water, stir, heat, add decolorizing agent, continue stirring and filtering, cool the collected second filtrate to crystallize, filter, and rinse, and dry and crush the collected filter cake to obtain inositol product, and combine the collected filtrate into the inositol phase;

[0011] (4) Take the salt phase described in step (1), add potassium salt or potassium hydroxide, adjust the pH of the salt phase to acidic, then concentrate, cool and crystallize, filter, and dry the collected third filter cake to obtain potassium dihydrogen phosphate product. The collected third filtrate is used for later use.

[0012] (5) Take the third filtrate from step (4), concentrate and filter it, and dry the collected fourth filter cake to obtain potassium chloride product; cool and filter the collected fourth filtrate, dry the collected fifth filter cake and combine it with the potassium dihydrogen phosphate product from step (4), and keep the collected fifth filtrate for later use.

[0013] (6) Take the fifth filtrate from step (5), concentrate and filter it, dry the collected filter cake and combine it with the potassium chloride product from step (5), and keep the collected sixth filtrate for later use.

[0014] (7) Take the sixth filtrate from step (6), cool it down, filter it, dry the collected filter cake and combine it with the potassium dihydrogen phosphate product from step (4), and use the collected filtrate as a liquid fertilizer component.

[0015] As an improved technical solution, in step (1), the chromatographic column packing material in the simulated moving bed chromatography separation system is calcium-type S1850 or potassium-type S1850 gel chromatography resin with a particle size of 300±40μm. The height-to-diameter ratio of the chromatographic column is 1-1.5:2.0, the feed rate is 10-15% v / v of the single column volume, and the feed, circulation, water top salt and water top inositol rates are controlled at 1-2 BV / h, with a running cycle of 15-30 min.

[0016] As an improved technical solution, in step (2), the inositol phase is concentrated to a solid content of 45-60 wt%, and then cooled to 25-35℃ for heat preservation and crystallization.

[0017] As an improved technical solution, in step (3), purified water is added at a mass-volume ratio of 1:1-1.5 and heated to 90-98℃; the second filtrate is cooled to 25-40℃ and kept warm for crystallization.

[0018] As an improved technical solution, the potassium salt added in step (4) is potassium carbonate or potassium bicarbonate. After adjusting the pH to 3.2-3.8, the solution is concentrated to obtain a concentrated solution with a solid content of 50-60wt%, and then cooled to 20-30℃ for crystallization.

[0019] As an improved technical solution, the third filtrate in step (5) is thermally concentrated to obtain a concentrate with a solid content of 65-75 wt%.

[0020] As an improved technical solution, in step (5), the fourth filtrate is cooled to 25-35℃ within 3 hours.

[0021] As an improved technical solution, the fifth filtrate in step (6) is concentrated to obtain a concentrate with a solid content of 60-70 wt%.

[0022] After adopting the above technical solution, the beneficial effects of the present invention are:

[0023] This invention involves first processing the collected potassium dihydrogen phosphate mother liquor using a simulated moving bed chromatography separation system to collect the salt phase and inositol phase separately. The inositol phase is concentrated, crystallized, and filtered to collect the first filtrate and the first filter cake. The first filter cake is added to purified water, heated and stirred, and then decolorized and filtered. The collected second filtrate is cooled, crystallized, filtered, and washed. The collected filter cake is dried to obtain the inositol product. The collected salt phase is adjusted to acidic pH with potassium salt or potassium hydroxide, concentrated, cooled, crystallized, and filtered. The collected third filter cake is dried to obtain the potassium dihydrogen phosphate product. The collected third filtrate is concentrated and filtered, and the collected fourth filter cake is dried to obtain the potassium chloride product. The collected fourth filtrate is cooled, crystallized, and filtered. The collected filter cake is dried and combined with the potassium dihydrogen phosphate product. The collected fifth filtrate is further concentrated and filtered, and the collected filter cake is dried and combined with the potassium chloride product. The collected sixth filtrate is cooled, filtered, and the collected filter cake is dried and combined with the potassium dihydrogen phosphate product. The above process first uses a simulated moving bed to separate inositol from potassium dihydrogen phosphate, potassium chloride, small molecule amino acids, proteins, etc. in the inositol mother liquor. The inositol phase is crystallized twice to obtain the inositol product. The salt phase utilizes the difference in solubility between potassium dihydrogen phosphate and potassium chloride to separate the two under different temperature conditions, which greatly improves the yield and purity of the inositol product. At the same time, it also obtains high-yield and high-volume potassium dihydrogen phosphate and potassium chloride products. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Example 1

[0026] A process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor includes the following steps:

[0027] (1) 1000L of potassium dihydrogen phosphate crystallization mother liquor (mother liquor solid content 29.3wt%, inositol concentration 37.6g / L, potassium dihydrogen phosphate concentration 238.9g / L, potassium chloride concentration 48.2g / L) was separated by a simulated moving bed chromatography system (the chromatographic column packing material was calcium type S1850 gel chromatography resin with a particle size of 300±40μm), the height-to-diameter ratio of the chromatographic column was 1:2.0, the feed rate was 10% v / v of the single column volume, the feed, circulation, water top salt and water top inositol rates were controlled at 1 BV / h, the running cycle was 30min (the volume of each chromatographic column was 50L, and the number of chromatographic columns was 6) and the inositol phase 1300L and salt phase 2700L were collected respectively.

[0028] (2) Take 1300L of the inositol phase from step (1), first concentrate it through a reverse osmosis membrane, then concentrate it by heat to a solid content of 45wt%, then cool it down to 25℃, keep it warm for crystallization, filter, and rinse, and collect 38.3kg of the first filter cake and 55L of the first filtrate (combined into the potassium dihydrogen phosphate mother liquor).

[0029] (3) Take 38.3 kg of the first filter cake from step (2), add 38.3 L of purified water at a mass-volume ratio of 1:1, stir, heat to 90°C, add decolorizing agent (689 g of activated carbon at a material volume ratio of 1%), continue stirring and filtering, cool the collected second filtrate to 25°C, keep it warm to crystallize, filter, and rinse, dry and crush the collected filter cake to obtain inositol product, and combine 42.7 L of collected filtrate into the inositol phase;

[0030] (4) Take 2700L of the salt phase from step (1), add potassium carbonate, adjust the pH of the salt phase to 3.2, and then concentrate to obtain a concentrated solution with a solid content of 50wt%, cool down to 20℃ for crystallization, filter, and dry the collected third filter cake to obtain potassium dihydrogen phosphate product. Collect 355L of the third filtrate for later use.

[0031] (5) Take 355L of the third filtrate from step (4), concentrate it by heat to obtain a concentrate with a solid content of 65wt%, filter it, and dry the collected fourth filter cake to obtain potassium chloride product; cool the collected fourth filtrate to 25℃ within 3h and filter it, dry the collected fifth filter cake and combine it with the potassium dihydrogen phosphate product from step (4), and keep 138.8L of the collected fifth filtrate for later use.

[0032] (6) Take 138.8L of the fifth filtrate from step (5), concentrate it by heat to obtain a concentrated solution with a solid content of 60wt%, filter it, dry the collected filter cake and combine it with the potassium chloride product from step (5), and collect 95.4L of the sixth filtrate for later use.

[0033] (7) Take 95.4 L of the sixth filtrate from step (6), cool it to 20°C within 3 hours and then filter it. After drying the collected filter cake, combine it with the potassium dihydrogen phosphate product from step (4). The collected filtrate is used as a liquid fertilizer component.

[0034] Example 2

[0035] A process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor includes the following steps:

[0036] (1) The collected 1000L potassium dihydrogen phosphate crystallization mother liquor (mother liquor solid content 29.3wt%, inositol concentration 37.6g / L, potassium dihydrogen phosphate concentration 238.9g / L, potassium chloride concentration 48.2g / L) was processed using a simulated moving bed chromatography separation system (the chromatographic column packing material was potassium-type gel chromatography resin with a particle size of 300±40μm, the height-to-diameter ratio of the chromatographic column was 1.3:2.0, the feed rate was 13% v / v of the single column volume, the feed, circulation, water-to-salt and water-to-inositol rates were controlled at 1.2 BV / h, the running cycle was 25.6min, (the chromatographic column volume was 65L, and the number of chromatographic columns was 6) and 1300L of inositol phase and 2700L of salt phase were collected respectively.

[0037] (2) Take 1300L of the inositol phase from step (1), first concentrate it through a reverse osmosis membrane, then concentrate it through heat to a solid content of 50wt%, then cool it down to 28℃, keep it warm to crystallize, filter, and rinse, and collect 39.8kg of the first filter cake and 43L of the first filtrate (combined into the potassium dihydrogen phosphate mother liquor).

[0038] (3) Take 39.8 kg of the first filter cake from step (2), add 47.8 L of purified water at a mass-to-volume ratio of 1:1.2, stir, heat to 92°C, add decolorizing agent (add 955 g of activated carbon at a material volume ratio of 1.2%), continue stirring and filtering, cool the collected second filtrate to 30°C, keep it warm to crystallize, filter, and rinse, dry and crush the collected filter cake to obtain inositol product, and combine 51.2 L of collected filtrate into the inositol phase;

[0039] (4) Take 2700L of the salt phase from step (1), add potassium hydroxide, adjust the pH of the salt phase to 3.4, and then concentrate to obtain a concentrated solution with a solid content of 52wt%, cool down to 23℃ for crystallization, filter, and dry the collected third filter cake to obtain potassium dihydrogen phosphate product. Collect 323.8L of the third filtrate for later use.

[0040] (5) Take 323.8L of the third filtrate from step (4), concentrate it by heat to obtain a concentrate with a solid content of 68wt%, filter it, and dry the collected fourth filter cake to obtain potassium chloride product; cool the collected fourth filtrate to 28℃ within 3h and filter it, dry the collected fifth filter cake and combine it with the potassium dihydrogen phosphate product from step (4), and keep 128.9L of the collected fifth filtrate for later use;

[0041] (6) Take 128.9L of the fifth filtrate from step (5), concentrate it by heat to obtain a concentrated solution with a solid content of 68wt%, filter it, dry the collected filter cake and combine it with the potassium chloride product from step (5), and collect 89.9L of the sixth filtrate for later use.

[0042] (7) Take 89.9 L of the sixth filtrate from step (6), cool it to 27°C within 3 hours and then filter it. After drying the collected filter cake, combine it with the potassium dihydrogen phosphate product from step (4). The collected filtrate is used as a component of liquid fertilizer.

[0043] Example 3

[0044] A process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor includes the following steps:

[0045] (1) The collected 1000L potassium dihydrogen phosphate crystallization mother liquor (mother liquor solid content 29.3wt%, inositol concentration 37.6g / L, potassium dihydrogen phosphate concentration 238.9g / L, potassium chloride concentration 48.2g / L) was processed using a simulated moving bed chromatography separation system (the chromatographic column packing material was potassium type S1850 gel chromatography resin with a particle size of 300±40μm, the height-to-diameter ratio of the chromatographic column was 1.5:2.0, the feed rate was 12% v / v of the single column volume, the feed, circulation, water top salt and water top inositol rates were controlled at 1.5 BV / h, the operation cycle was 20.4min, (the chromatographic column volume was 75L, and the number of chromatographic columns was 6) and 1300L of inositol phase and 2700L of salt phase were collected respectively.

[0046] (2) Take 1300L of the inositol phase from step (1), first concentrate it through a reverse osmosis membrane, then concentrate it by heat to a solid content of 53wt%, then cool it to 30℃, keep it warm for crystallization, filter, and rinse, and collect 39.9kg of the first filter cake and 40L of the first filtrate (combined into the potassium dihydrogen phosphate mother liquor).

[0047] (3) Take 39.9 kg of the first filter cake from step (2), add 59.9 L of purified water at a mass-volume ratio of 1:1.5, stir, heat to 95°C, add decolorizing agent (1377 g of activated carbon at a material volume ratio of 1.5%), continue stirring and filtering, cool the collected second filtrate to 32°C, keep it warm to crystallize, filter, and rinse. The collected filter cake is dried and crushed to obtain the inositol product. The collected filtrate of 62.1 L is combined into the inositol phase.

[0048] (4) Take 2700L of the salt phase from step (1), add potassium hydroxide, adjust the pH of the salt phase to 3.5, and then concentrate to obtain a concentrated solution with a solid content of 55wt%. Cool down to 25℃ and keep it warm to crystallize. Filter and dry the collected third filter cake to obtain potassium dihydrogen phosphate product. Collect 293.9L of the third filtrate for later use.

[0049] (5) Take 293.9L of the third filtrate from step (4), concentrate it by heat to obtain a concentrated solution with a solid content of 70wt%, filter it, and dry the collected fourth filter cake to obtain potassium chloride product; cool the collected fourth filtrate to 30℃ within 3h and filter it, dry the collected fifth filter cake and combine it with the potassium dihydrogen phosphate product from step (4), and keep 122.2L of the collected fifth filtrate for later use;

[0050] (6) Take 122.2L of the fifth filtrate from step (5), concentrate it by heat to obtain a concentrate with a solid content of 65wt%, filter it, dry the collected filter cake and combine it with the potassium chloride product from step (5), and collect 86.5L of the sixth filtrate for later use.

[0051] (7) Take 86.5L of the sixth filtrate from step (6), cool it to 30°C within 3 hours and then filter it. After drying the collected filter cake, combine it with the potassium dihydrogen phosphate product from step (4). The collected filtrate is used as a liquid fertilizer component.

[0052] Example 4

[0053] A process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor includes the following steps:

[0054] (1) The collected 1000L potassium dihydrogen phosphate crystallization mother liquor (mother liquor solid content 29.3wt%, inositol concentration 37.6g / L, potassium dihydrogen phosphate concentration 238.9g / L, potassium chloride concentration 48.2g / L) was processed using a simulated moving bed chromatography separation system (the chromatographic column packing material was calcium type S1850 gel chromatography resin with a particle size of 300±40μm, the height-to-diameter ratio of the chromatographic column was 1.2:2.0, the feed rate was 15% v / v of the single column volume, the feed, circulation, water top salt and water top inositol rates were controlled at 1.8 BV / h, the operation cycle was 17.7min, (the chromatographic column volume was 60L, and the number of chromatographic columns was 6) and 1300L of inositol phase and 2700L of salt phase were collected respectively.

[0055] (2) Take 1300L of the inositol phase from step (1), first concentrate it through a reverse osmosis membrane, then concentrate it by heat to a solid content of 56wt%, then cool it to 32℃, keep it warm for crystallization, filter, and rinse, and collect 40.3kg of the first filter cake and 38L of the first filtrate (combined into the potassium dihydrogen phosphate mother liquor).

[0056] (3) Take 40.3 kg of the first filter cake from step (2), add 60.5 L of purified water at a mass-volume ratio of 1:1.5, stir, heat to 98°C, add decolorizing agent (1669 g of activated carbon at a material volume ratio of 1.8%), continue stirring and filtering, cool the collected second filtrate to 38°C, keep it warm to crystallize, filter, and rinse. The collected filter cake is dried and crushed to obtain the inositol product. The collected filtrate of 65.2 L is combined into the inositol phase.

[0057] (4) Take 2700L of the salt phase from step (1), add potassium bicarbonate, adjust the pH of the salt phase to 3.7, and then concentrate to obtain a concentrated solution with a solid content of 58wt%, cool to 28℃ for crystallization, filter, and dry the collected third filter cake to obtain potassium dihydrogen phosphate product. Collect 267.3L of the third filtrate for later use.

[0058] (5) Take 267.3L of the third filtrate from step (4), concentrate it by heat to obtain a concentrate with a solid content of 72wt%, filter it, and dry the collected fourth filter cake to obtain potassium chloride product; cool the collected fourth filtrate to 33℃ within 3h and filter it, dry the collected fifth filter cake and combine it with the potassium dihydrogen phosphate product from step (4), and keep 117.9L of the collected fifth filtrate for later use;

[0059] (6) Take 117.9L of the fifth filtrate from step (5), concentrate it by heat to obtain a concentrate with a solid content of 67wt%, filter it, dry the collected filter cake and combine it with the potassium chloride product from step (5), and collect 83.6L of the sixth filtrate for later use.

[0060] (7) Take 83.6L of the sixth filtrate from step (6), cool it to 33°C within 3 hours and then filter it. After drying the collected filter cake, combine it with the potassium dihydrogen phosphate product from step (4). The collected filtrate is used as a liquid fertilizer component.

[0061] Example 5

[0062] A process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor includes the following steps:

[0063] (1) The collected 1000L potassium dihydrogen phosphate crystallization mother liquor (mother liquor solid content 29.3wt%, inositol concentration 37.6g / L, potassium dihydrogen phosphate concentration 238.9g / L, potassium chloride concentration 48.2g / L) was separated by a simulated moving bed chromatography system (the chromatographic column packing material was calcium type S1850 gel chromatography resin with a particle size of 300±40μm), the height-to-diameter ratio of the chromatographic column was 1.5:2.0, the feed rate was 13% v / v of the single column volume, the feed, circulation, water top salt and water top inositol rates were controlled at 2BV / h, the running cycle was 15.6min (the chromatographic column volume was 75L, the number of chromatographic columns was 6) was processed, and 1300L of inositol phase and 2700L of salt phase were collected respectively.

[0064] (2) Take 1300L of the inositol phase from step (1), first concentrate it through a reverse osmosis membrane, then heat concentrate it to a solid content of 60wt%, then cool it down to 35℃, keep it warm for crystallization, filter, and rinse, and collect 41.1kg of the first filter cake and 39L of the first filtrate (combined into the potassium dihydrogen phosphate mother liquor).

[0065] (3) Take 41.1 kg of the first filter cake from step (2), add 61.7 L of purified water at a mass-volume ratio of 1:1.5, stir, heat to 98°C, add decolorizing agent (1892 g of activated carbon at a material volume ratio of 2%), continue stirring and filtering, cool the collected second filtrate to 40°C, keep it warm to crystallize, filter, and rinse, dry and crush the collected filter cake to obtain inositol product, and combine 64.8 L of collected filtrate into the inositol phase;

[0066] (4) Take 2700L of the salt phase from step (1), add potassium hydroxide, adjust the pH of the salt phase to 3.8, and then concentrate to obtain a concentrated solution with a solid content of 60wt%, cool down to 30℃ for crystallization, filter, and dry the collected third filter cake to obtain potassium dihydrogen phosphate product. 249.9L of the collected third filtrate is used for later use.

[0067] (5) Take 249.9L of the third filtrate from step (4), concentrate it by heat to obtain a concentrate with a solid content of 75wt%, filter it, and dry the collected fourth filter cake to obtain potassium chloride product; cool the collected fourth filtrate to 35℃ within 3h and filter it, dry the collected fifth filter cake and combine it with the potassium dihydrogen phosphate product from step (4), and keep 110.8L of the collected fifth filtrate for later use;

[0068] (6) Take 110.8L of the fifth filtrate from step (5), concentrate it by heat to obtain a concentrated solution with a solid content of 70wt%, filter it, dry the collected filter cake and combine it with the potassium chloride product from step (5), and collect 79.4L of the sixth filtrate for later use.

[0069] (7) Take 79.4 L of the sixth filtrate from step (6), cool it to 30 °C within 3 hours and then filter it. After drying the collected filter cake, combine it with the potassium dihydrogen phosphate product from step (4). The collected filtrate is used as a liquid fertilizer component.

[0070] To better demonstrate that the process of the present invention can yield high yields of inositol, as well as high quantities of potassium dihydrogen phosphate and potassium chloride, 11 comparative examples are provided with reference to Example 3, as detailed below.

[0071] Comparative Example 1

[0072] Unlike Example 3, the chromatographic column in step (1) has a particle size of 500 μm, while the rest of the operation is the same.

[0073] Comparative Example 2

[0074] Unlike Example 3, in step (1), the resin in the chromatographic column is S1160 resin, which is a uniform particle size (300±40μm) styrene-propylene chromatographic resin, and the rest of the operation is the same.

[0075] Comparative Example 3

[0076] Unlike Example 3, in step (2), the temperature is lowered to 15°C, while the rest of the operation is the same.

[0077] Comparative Example 4

[0078] Unlike Example 3, in step (2), the temperature is lowered to 40°C, while the rest of the operation is the same.

[0079] Comparative Example 5

[0080] Unlike Example 3, in step (3), the temperature is lowered to 20°C, while the rest of the operation is the same.

[0081] Comparative Example 6

[0082] Unlike Example 3, in step (3), the temperature is lowered to 45°C, while the rest of the operation is the same.

[0083] Comparative Example 7

[0084] Unlike Example 3, in step (4), the pH is adjusted to 2.8, while the rest of the operation is the same.

[0085] Comparative Example 8

[0086] Unlike Example 3, in step (4), the pH is adjusted to 4.2, while the rest of the operation is the same.

[0087] Comparative Example 9

[0088] Unlike Example 3, in step (4), the temperature is lowered to 15°C, while the rest of the operation is the same.

[0089] Comparative Example 10

[0090] Unlike Example 3, in step (4), the temperature is lowered to 35°C, while the rest of the operation is the same.

[0091] Comparative Example 11

[0092] Unlike Example 3, in step (5), the temperature is lowered to 25°C within 4 hours, while the rest of the operation is the same.

[0093] Table 1

[0094] Example Inositol yield (kg), percentage (%), and purity (%) Yield (kg), purity (%) of potassium dihydrogen phosphate Potassium chloride yield (kg), yield (%), purity (%) Example 1 31.2、82.6、99.6 265.2、93.4、98.5 42.5、87.0、98.7 Example 2 31.7、83.8、99.4 265.2、93.5、98.4 42.8、87.5、98.5 Example 3 32.4、85.9、99.7 267.9、94.9、99.0 43.1、88.3、98.7 Example 4 31.5、83.4、99.5 266.8、94.4、98.9 43.2、88.0、98.2 Example 5 31.3、82.9、99.6 267.5、94.2、98.5 43.1、87.7、98.1 Comparative Example 1 27.5、72.2、98.7 265.5、89.6、94.4 46.6、77.6、80.3 Comparative Example 2 0、0、0 269.8、87.3、90.5 31.5、28.2、43.2 Comparative Example 3 30.8、79.4、96.9 266.8、94.4、98.9 42.7、87.2、98.4 Comparative Example 4 28.5、75.5、99.6 266.2、93.9、98.6 42.5、86.9、98.5 Comparative Example 5 33.9、87.3、96.8 267.5、94.4、98.7 43.1、88.3、98.7 Comparative Example 6 27.6、73.2、99.7 266.1、93.8、98.6 42.5、86.9、98.5 Comparative Example 7 32.3、85.5、99.5 257.2、87.8、95.4 37.6、72.9、93.5 Comparative Example 8 32.1、84.9、99.4 251.6、87.3、97.0 38.6、73.9、92.3 Comparative Example 9 32.4、85.7、99.5 287.8、95.4、92.7 40.2、76.3、91.5 Comparative Example 10 32.3、85.4、99.4 255.2、87.9、96.3 36.1、65.4、87.3 Comparative Example 11 31.9、84.6、99.7 271.8、91.8、94.4 38.5、76.0、95.2

[0095] As can be seen from Table 1, the inositol yield, recovery rate, and purity, as well as the potassium dihydrogen phosphate yield, potassium chloride yield, recovery rate, and purity obtained in Example 3 using the process method of the present invention are significantly higher than those of other examples and comparative examples 1-11.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor, characterized in that, Includes the following steps: (1) The collected potassium dihydrogen phosphate crystallization mother liquor was processed using a simulated moving bed chromatography separation system to collect the inositol phase and salt phase respectively; the packing material of the chromatographic column in the simulated moving bed chromatography separation system was calcium type S1850 or potassium type S1850 gel chromatography resin with a particle size of 300±40μm. (2) Take the inositol phase described in step (1), concentrate it, cool it to 25-35℃ and keep it warm to crystallize, filter it, and rinse it. Collect the first filter cake and the first filtrate respectively. Combine the first filtrate with the potassium dihydrogen phosphate mother liquor. (3) Take the first filter cake from step (2), add purified water, stir, heat, add decolorizing agent, continue stirring and filtering, cool the collected second filtrate to 25-40℃ for crystallization, filter, and rinse, dry and crush the collected filter cake to obtain inositol product, and combine the collected filtrate into the inositol phase; (4) Take the salt phase described in step (1), add potassium salt or potassium hydroxide, adjust the pH of the salt phase to 3.2-3.8, then concentrate, cool to 20-30℃ for crystallization, filter, and dry the collected third filter cake to obtain potassium dihydrogen phosphate product. The collected third filtrate is used for later use. (5) Take the third filtrate from step (4), concentrate and filter it, and dry the collected fourth filter cake to obtain potassium chloride product; cool and filter the collected fourth filtrate, dry the collected fifth filter cake and combine it with the potassium dihydrogen phosphate product from step (4), and keep the collected fifth filtrate for later use. (6) Take the fifth filtrate from step (5), concentrate and filter it, dry the collected filter cake and combine it with the potassium chloride product from step (5), and keep the collected sixth filtrate for later use. (7) Take the sixth filtrate from step (6), cool it down, filter it, dry the collected filter cake and combine it with the potassium dihydrogen phosphate product from step (4), and use the collected filtrate as a liquid fertilizer component.

2. The process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, In step (1), the height-to-diameter ratio of the chromatographic column is 1-1.5:2.0, the feed rate is 10-15% v / v of the single column volume, the feed, circulation, water top salt and water top inositol rates are controlled at 1-2 BV / h, and the running cycle is 15-30 min.

3. The process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, In step (2), the inositol phase is concentrated to a solid content of 45-60 wt%.

4. The process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, In step (3), purified water is added at a mass-volume ratio of 1:1-1.5 and heated to 90-98℃.

5. The process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, The potassium salt added in step (4) is potassium carbonate or potassium bicarbonate, and the concentrate is concentrated to obtain a concentrate with a solid content of 50-60 wt%.

6. The process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, In step (5), the third filtrate is thermally concentrated to obtain a concentrate with a solid content of 65-75 wt%.

7. The process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, In step (5), the fourth filtrate is cooled to 25-35℃ within 3 hours.

8. The process for recovering potassium dihydrogen phosphate, potassium chloride, and inositol from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, In step (6), the fifth filtrate is concentrated to obtain a concentrated solution with a solid content of 60-70 wt%.