A system for reducing chloride ions in a lean organic phase in a system for producing potassium dihydrogen phosphate from crude phosphoric acid by organic extraction

Abstract

The utility model discloses a system of removing chlorine ion in lean organic phase in the system of crude phosphoric acid organic extraction production potassium dihydrogen phosphate, which comprises: a back extraction tank for reacting hydrochloric acid organic phase with ammonia water to generate ammonium chloride and separating phases; an aging tank connected to the outlet of the back extraction tank for static separation and phase separation to precipitate a chlorine-containing water phase; a multi-stage countercurrent water washing tank comprising at least three series-connected water washing tanks for washing the organic phase step by step; and an adsorption tower connected to the outlet of the last-stage water washing tank and provided with an adsorbent for further removing chlorine ions in the organic phase. The utility model fully utilizes washing water, reduces water consumption, realizes a chlorine ion removal rate of 94% to 96% in the lean organic phase, improves the purity of potassium dihydrogen phosphate products, prolongs the service life of the extraction agent, and systematically solves the industry problem that it is difficult to remove alkyl halides in the lean organic phase.

Description

Technical Field

[0001] This invention relates to the field of solvent regeneration technology in the extraction method for producing potassium dihydrogen phosphate, specifically to a system for reducing chloride ions in a lean organic phase. Background Technology

[0002] In the traditional solvent extraction process for producing potassium dihydrogen phosphate, phosphoric acid and potassium chloride form a mixed solution, and then a mixture of amines and alcohols is used as the extractant. The extractant selectively extracts hydrochloric acid. After phase separation, the aqueous phase is a potassium dihydrogen phosphate solution, and the organic phase is an organic phase containing hydrochloric acid. This organic phase containing hydrochloric acid is back-extracted with ammonia and then recycled.

[0003] However, in actual production, after the ammonia and organic phases are mixed in the back-extraction tank and separated, ammonium chloride enters the aqueous phase, while the organic phase (this organic phase is called the lean organic phase) contains ammonium chloride droplets and a small amount of unreacted hydrochloric acid, which enters the potassium dihydrogen phosphate product. Moreover, due to the long-term recycling of the extractant, a small amount of organic hydrogen atoms are replaced by chlorine, resulting in alkane chlorination. Organic matter with hydrogen atoms replaced by chlorine not only affects the extraction efficiency of hydrochloric acid, but is also difficult to remove using conventional methods.

[0004] After the extractant is recycled, ammonium chloride and unreacted hydrochloric acid are trapped in the lean organic phase, resulting in a high chloride ion content (chloride ion content > 0.2%) in the product, which affects product quality. Existing extraction methods for producing potassium dihydrogen phosphate lack systematic methods for removing chloride ions from the lean organic phase, especially alkane chlorides, which are difficult to remove effectively. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies and provide a system for systematically and efficiently removing chloride ions from the organic-poor phase in a crude phosphoric acid organic extraction process for producing potassium dihydrogen phosphate. This system utilizes a three-stage coupled process of physical sedimentation, multi-stage countercurrent washing, and adsorption to remove chloride ions from the organic-poor phase in a systematic and efficient manner.

[0006] The technical solution adopted by this utility model is as follows: A system for reducing chloride ions in an organic-lean phase during the organic extraction of crude phosphoric acid to produce potassium dihydrogen phosphate includes: The back-extraction tank is used to react the hydrochloric acid-containing organic phase with ammonia water to generate ammonium chloride and separate the phases. The generated ammonium chloride enters the lower aqueous phase, and the organic phase with reduced hydrochloric acid content is called the lean organic phase. The aging tank, connected to the outlet of the back-extraction tank, is used for static separation to precipitate the chloride-containing aqueous phase. Here, the organic-lean phase enters the aging tank, and after static separation, the lower layer is the aqueous phase, and the upper layer is the organic phase. After aging, the chloride ion content of the organic phase is reduced by 10-15%. A multi-stage countercurrent washing tank, comprising at least three washing tanks connected in series, is used for washing the organic phase in stages; the organic phase after aging tank is sent to the multi-stage countercurrent washing tank, and after three stages of countercurrent washing, the chloride ion content of the organic phase is reduced by 80-85%; The adsorption tower, connected to the outlet of the last stage water washing tank, contains adsorbent for further removal of chloride ions from the organic phase. The organic phase, after passing through the multi-stage countercurrent water washing tank, is then fed back into the adsorption tower, where the chloride ion content of the organic phase is reduced by 94-96%.

[0007] Furthermore, the settling time of the organic-poor phase in the aging tank is 4 to 10 hours.

[0008] Furthermore, the multi-stage countercurrent washing tank has a three-stage structure, including washing tanks #1, #2, and #3, with a washing temperature of 10~15℃.

[0009] Furthermore, the volume ratio of organic phase to water in the No. 3 washing tank is (5~7):1.

[0010] Furthermore, the adsorbent used in the adsorption tower is coconut shell activated carbon with an iodine adsorption value ≥1000mg / g, and the mass ratio of adsorbent to organic phase is (100~500):1.

[0011] Furthermore, the temperatures of the back-extraction tank, aging tank, washing tank, and adsorption tower are controlled at 10~20℃, 5~10℃, 10~15℃, and 5~10℃, respectively.

[0012] Furthermore, the multi-stage countercurrent water washing tank has 3 to 7 stages, which can be adjusted according to the chloride ion requirements of the product.

[0013] Furthermore, the system also includes chloride ion concentration detection points, which are respectively set at the outlets of the lean organic phase, the water washing tanks at each stage, and the adsorption tower outlet, for real-time monitoring of chloride ion removal effect.

[0014] The beneficial effects of this utility model are: 1. This utility model forms a synergistic dechlorination mechanism by coupling physical sedimentation, multi-stage countercurrent washing and adsorption dechlorination three-stage processes, so that the chloride ion removal rate in the lean organic phase reaches 94%~96%.

[0015] 2. The chloride ion content in the organic phase after processing by this system is reduced, effectively preventing chlorine-containing substances from participating in the extractant cycle, and reducing the chloride ion content in the final product potassium dihydrogen phosphate to <0.03%, thereby improving product quality and purity.

[0016] 3. The system of this utility model can not only remove chloride ions in the form of ammonium chloride and hydrochloric acid, but also effectively adsorb and remove the extractant that has undergone alkane chlorination reaction, slow down the performance decay of the extractant, extend the service life of the extractant, and improve the quality of potassium dihydrogen phosphate products.

[0017] 4. The multi-stage countercurrent washing tank of this utility model can be flexibly set to 3-7 stages according to the chloride ion content requirements of the product. The adsorbent addition ratio can be adjusted within the range of 100:1 to 500:1 to adapt to different production needs and raw material characteristics. By setting a reasonable temperature gradient and optimizing process parameters, the system can be made stable, with good dechlorination effect, and is suitable for continuous industrial production.

[0018] 5. This utility model adopts a countercurrent washing method, makes full use of washing water, reduces water consumption, and systematically solves the industry problem of the difficulty in removing alkane chlorides in the lean organic phase, providing technical support for the production of high-purity potassium dihydrogen phosphate by solvent extraction. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process flow of this utility model. Detailed Implementation

[0020] The content of this utility model will be further described below with reference to the accompanying drawings and embodiments.

[0021] like Figure 1 As shown, a system for reducing chloride ions in an organic-lean phase during crude phosphoric acid organic extraction to produce potassium dihydrogen phosphate includes: The back-extraction tank is used to react the hydrochloric acid-containing organic phase with ammonia water to generate ammonium chloride and separate the phases. The generated ammonium chloride enters the lower aqueous phase, and the organic phase with reduced hydrochloric acid content is called the lean organic phase. The aging tank, connected to the outlet of the back-extraction tank, is used for settling and phase separation. The chlorine-containing aqueous phase is precipitated, and the organic-lean phase enters the aging tank. After settling for 4 to 10 hours, phase separation occurs, with the lower layer being the aqueous phase and the upper layer being the organic phase. After aging, the chloride ion content of the organic phase decreases by 10 to 15%. A multi-stage counter-current washing tank, comprising at least three washing tanks connected in series, is used for washing the organic phase in stages; the organic phase is fed into the multi-stage counter-current washing, and after three stages of counter-current washing, the chloride ion content of the organic phase is reduced by 80-85%; The adsorption tower, connected to the outlet of the last-stage washing tank, contains adsorbent for further removal of chloride ions from the organic phase. The organic phase is then fed back into the adsorption tower, where the chloride ion content is reduced by 94-96%.

[0022] The number of stages in the multi-stage countercurrent water washing tank can be adjusted to 3-7 stages according to the chloride ion requirements of the product. For example, it can be adjusted to a three-stage structure, including water washing tanks (1#, 2#, 3#), with a water washing temperature of 10-15℃. The volume ratio of organic phase to water in the 3# water washing tank is (5-7):1. The temperatures of the back-extraction tank, aging tank, water washing tank, and adsorption tower are controlled at 10-20℃, 5-10℃, 10-15℃, and 5-10℃, respectively, to form a temperature gradient conducive to chloride ion removal. The reasonable temperature gradient and optimized process parameters ensure stable system operation, good dechlorination effect, and suitability for continuous industrial production.

[0023] The adsorbent used in the adsorption tower is coconut shell activated carbon with an iodine adsorption value ≥1000mg / g. The mass ratio of adsorbent to organic phase is (100~500):1. This can effectively adsorb and remove the extractant that has undergone alkane chlorination reaction, slow down the performance decay of the extractant, extend the service life of the extractant, and improve the quality of potassium dihydrogen phosphate product.

[0024] The system may also include chloride ion concentration detection points, which are respectively set at the outlets of the lean organic phase, each stage of the water washing tank, and the adsorption tower outlet, for real-time monitoring of chloride ion removal effect and adjustment of the multi-stage countercurrent water washing tank according to the product chloride ion requirements.

[0025] The system in the following embodiment includes a back-extraction tank, an aging tank, a three-stage countercurrent water washing tank (1#, 2#, 3#), and an adsorption tower. The adsorbent used in the adsorption tower is coconut shell activated carbon with an iodine adsorption value of 1800 mg / g. The organic phase containing hydrochloric acid reacts with ammonia water in the back-extraction tank. After phase separation, the lean organic phase enters the aging tank and is left to stand for 4-10 hours to precipitate a chlorine-containing aqueous phase. Subsequently, the organic phase enters the three-stage water washing tank for countercurrent washing and finally enters the adsorption tower for deep dechlorination.

[0026] Example 1 like Figure 1 As shown, the chloride ion content in the lean organic phase is 5000 mg / m³. 3 The settling time in the aging tank was controlled at 4 hours. The temperatures of each section of the system were as follows: back-extraction tank 15℃, aging tank 8℃, water washing tank 12℃, and adsorption tower 8℃. The ratio of organic phase to water in the No. 3 water washing tank was 5:1, and the mass ratio of adsorbent to organic phase was 100:1. After stable operation, the chloride ion removal effect is shown in the table below:

[0027] After dechlorination treatment by this system, the chloride ion content in organic phase 5 was reduced to 280 mg / m³.

[0028] Example 2 like Figure 1 As shown, the chloride ion content in the lean organic phase is 5000 mg / m³. 3In this embodiment, the ratio of organic phase to water in the No. 3 washing tank was adjusted to 6:1, while the other conditions remained the same as in Example 1. The chloride ion removal effect was further improved, and the chloride ion removal effect is shown in the table below:

[0029] After dechlorination treatment by this system, the chloride ion content in organic phase 5 was reduced to 230 mg / m³.

[0030] This invention achieves efficient and stable removal of chloride ions from organic-lean phases through systematic integration and process optimization, and has significant industrial application value.

[0031] The embodiments described above are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Various modifications and improvements made to the technical solutions of the present utility model by those skilled in the art without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.

Claims

1. A system for reducing chloride ions in an organic-lean phase during crude phosphoric acid organic extraction to produce potassium dihydrogen phosphate, characterized in that, include: The back-extraction tank is used to react the hydrochloric acid-containing organic phase with ammonia water to generate ammonium chloride and then separate the phases. The aging tank, connected to the outlet of the back-extraction tank, is used for settling and phase separation to precipitate the chlorine-containing aqueous phase; A multi-stage counter-current washing tank, comprising at least three washing tanks connected in series, is used for washing the organic phase in stages. The adsorption tower, connected to the outlet of the last-stage washing tank, contains adsorbent for further removal of chloride ions from the organic phase.

2. The system according to claim 1, characterized in that, The settling time for the depleted organic phase in the aging tank is 4 to 10 hours.

3. The system according to claim 1, characterized in that, The multi-stage countercurrent water washing tank has a three-stage structure, including washing tanks #1, #2, and #3, with a water washing temperature of 10~15℃.

4. The system according to claim 3, characterized in that, The volume ratio of organic phase to water in the No. 3 washing tank is (5~7):

1.

5. The system according to claim 1, characterized in that, The adsorbent used in the adsorption tower is coconut shell activated carbon with an iodine adsorption value ≥1000mg / g, and the mass ratio of adsorbent to organic phase is (100~500):

1.

6. The system according to claim 1, characterized in that, The temperatures of the back-extraction tank, aging tank, washing tank, and adsorption tower are controlled at 10~20℃, 5~10℃, 10~15℃, and 5~10℃, respectively.

7. The system according to claim 1, characterized in that, The multi-stage counter-current water washing tank has 3 to 7 stages, which can be adjusted according to the chloride ion requirements of the product.

8. The system according to any one of claims 1 to 7, characterized in that, The system also includes chloride ion concentration detection points, which are respectively set at the outlets of the lean organic phase, the water washing tanks at each stage, and the adsorption tower outlet, for real-time monitoring of chloride ion removal effect.

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