Recycling method for hydrochloric acid method food-grade phosphoric acid TBP compound extraction agent

Abstract

The invention relates to the field of food-grade phosphoric acid production, and discloses a recycling method for a hydrochloric acid method food-grade phosphoric acid TBP compound extracting agent. The recycling method comprises the following steps: carrying out alkali washing and 1-4-stage countercurrent washing on a recycled TBP compound extracting agent by using a NaOH solution to remove degradation products and impurities in an organic phase; washing the alkali-washed organic phase with process water or desalted water, and carrying out 1-4-stage countercurrent washing until the organic phase is neutral; acidizing the washed organic phase by using hydrochloric acid to recover the extraction performance; and recycling the acidified organic phase to a hydrochloric acid method food-grade phosphoric acid production process. According to the recycling method, the regeneration efficiency of the TBP compound extracting agent is obviously improved, the production cost of the hydrochloric acid process food-grade phosphoric acid is reduced, and the recycling method has important significance on industrial continuous production of the hydrochloric acid process food-grade phosphoric acid.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of food-grade phosphoric acid production, more particularly, it relates to a recycling method of TBP complexing extractant for food-grade phosphoric acid produced by hydrochloric acid method. BACKGROUND

[0002] Phosphoric acid is an important chemical raw material, which is widely used in fertilizer industry, food industry, water treatment industry, electronic industry, coating industry and many other fields. Food-grade phosphoric acid is also a cheap acidulant, which is widely used as food additive in the production process of dairy products, meat products, aquatic products and various beverages. The demand for food-grade phosphoric acid is very large at home and abroad, but the preparation method has been relatively backward.

[0003] In the process of producing food-grade phosphoric acid by hydrochloric acid method, the complexing extractant composed of phosphoric acid tributyl ester (TBP) and kerosene is widely used due to its good extraction selectivity and stability. However, during long-term continuous operation, the TBP complexing extractant will degrade to generate by-products, which will cause the color of the extractant to deepen and the extraction rate to decrease significantly.

[0004] At present, the regeneration methods of TBP complexing extractant in industry mainly include water washing method, adsorption method and distillation method. However, the water washing method only uses process water or desalted water to wash the organic phase, which can remove part of water-soluble impurities, but the removal effect of TBP degradation products is limited, and the recovery of extraction rate is insufficient; the adsorption method uses activated carbon or silica gel to adsorb impurities, but the adsorbent is easy to saturate, needs to be replaced frequently, and cannot repair the degraded TBP molecules; the distillation method recovers TBP by high-temperature distillation, but the energy consumption is high.

[0005] Therefore, it is of great significance to develop an efficient and low-cost regeneration method of TBP complexing extractant for the industrialized continuous production of food-grade phosphoric acid by hydrochloric acid method. SUMMARY

[0006] The purpose of the present application is to develop an efficient and low-cost regeneration method of TBP complexing extractant.

[0007] In order to achieve the above-mentioned purpose of the application, the following technical solutions are adopted in the present application:

[0008] The present application discloses a recycling method of TBP complexing extractant for food-grade phosphoric acid produced by hydrochloric acid method, which comprises the following steps:

[0009] Step 1, using NaOH solution to alkali wash the recycled TBP complexing extractant, 1~4 stage countercurrent washing, removing degradation products and impurities in the organic phase;

[0010] Step 2, using process water or desalted water to wash the organic phase after alkaline washing, 1-4 stages of countercurrent washing until the organic phase is neutral;

[0011] Step 3, using hydrochloric acid to acidify the organic phase after water washing to restore the extraction performance;

[0012] Step 4, the acidified organic phase is reused in the production process of food-grade phosphoric acid by hydrochloric acid method.

[0013] Further, in step 1, the reused TBP complexing extractant is washed with 4-10% NaOH solution.

[0014] Further, in step 1, the volume ratio of NaOH solution to organic phase is (0.5-2):1.

[0015] Further, in step 1, the washing temperature is 20-50°C and the washing time is 30-60 minutes.

[0016] Further, in step 2, the volume ratio of process water or desalted water to organic phase is (0.5-2):1.

[0017] Further, in step 2, the water washing temperature is 20-50°C and the washing time is 30-60 minutes.

[0018] Further, in steps 1 and 2, 2 stages of countercurrent washing are used in the washing process.

[0019] Further, in step 3, 4 mol / L hydrochloric acid is used to acidify the organic phase after water washing.

[0020] Further, in step 3, the amount of hydrochloric acid used is 30-100% of the volume of the organic phase and the acidification time is 20-40 minutes.

[0021] Further, in step 4, before reuse, a detection step is included, which is: taking the regenerated organic phase and mixing it with a solution containing phosphoric acid at a volume ratio of (3-5):1 to determine the secondary countercurrent extraction rate of phosphoric acid. If the extraction rate is ≥75%, it is determined to be qualified, and unqualified products are reprocessed from step 1 to step 3.

[0022] In summary, the present application has the following beneficial effects:

[0023] TBP complexing extractant will darken in color and the extraction rate will decrease significantly over time. In production, the organic phase is washed with 4-10% NaOH solution, 1-4 stages of countercurrent washing, and the washed organic phase is reused and washed with process water or desalted water, 1-4 stages of countercurrent washing. The color of the organic phase becomes clear, and the washed organic phase can achieve extraction effect after acidification with 2-4 mol / L hydrochloric acid.

[0024] The recycling method of the application significantly improves the regeneration efficiency of the TBP complexing extractant, and is conducive to reducing the production cost of food-grade phosphoric acid by hydrochloric acid method, and has important significance for the industrialized continuous production of food-grade phosphoric acid by hydrochloric acid method. DETAILED DESCRIPTION

[0025] The technical solutions and effects of the application are further described in detail below in conjunction with examples. It can be understood that the specific examples described herein are only used to explain the application, and not to limit the application.

[0026] In the patent (CN102515134A) of the applicant's prior application, a production process of food-grade phosphoric acid by hydrochloric acid method is described, which includes the following steps: taking 200 grams of poor phosphate ore containing about 20% P2O5, crushing to 20 mesh or more, and then adding into a beaker; adding 400 ml of 23 wt% hydrochloric acid and a part of water, and adding 14 ml of 6 wt% Na2S solution under stirring for 20 minutes for pre-removing impurities, then adding 10 ml of 0.1 wt% flocculant for flocculation and precipitation, and then filtering with filter paper; using a mixed solvent of volume percentage N235: isooctanol: kerosene = 15%: 15%: 70% to extract the filtrate to remove iron, the extraction temperature is 20-30℃, the extraction phase: water phase = 1:1, and the obtained raffinate water phase is the iron-removed dilute phosphoric acid; then, using a mixed solvent of phosphoric acid tributyl ester and kerosene as an extractant to extract the iron-removed dilute phosphoric acid for ten times, the extraction temperature is 20-30℃, the volume ratio of phosphoric acid tributyl ester: kerosene = 1:1, and the water phase: organic phase = 1:4 during extraction; then, using 15 wt% dilute phosphoric acid solution to wash the organic phase obtained by extraction for five times, the water phase: organic phase = 1:25 during washing; then, using 1 wt% dilute hydrochloric acid to back-extract the organic phase for five times, the water phase obtained by back-extraction is the dilute phosphoric acid solution, the water phase: organic phase = 1:10 during back-extraction, and the organic phase after back-extraction is back-extracted with pure water for five times to return the organic phase to the extraction process for recycling, the water phase: organic phase = 1:10 during back-extraction with pure water; then, adding 4 ml of 6 wt% Na2S solution to the dilute phosphoric acid solution for removing impurities; adding 5 g of activated carbon to the dilute phosphoric acid solution for stirring to remove organic matter therein; filtering with filter paper; adding 1 ml of 30 wt% hydrogen peroxide to the dilute phosphoric acid solution for removing easily oxidizable substances; evaporating and concentrating the dilute phosphoric acid solution, the evaporation temperature is 158℃; adding 1 g of activated carbon to the cooled dilute phosphoric acid solution for stirring to decolorize, and then filtering with a sand core funnel to obtain 56.4 grams of colorless and transparent finished product phosphoric acid.

[0027] The present application is based on the patent, and the inventors find that in the process of producing food-grade phosphoric acid by hydrochloric acid method, the TBP complexing extractant will degrade to generate byproducts, which will cause the color of the extractant to deepen and the extraction rate to decrease significantly. Therefore, the present application develops a high-efficiency and low-cost regeneration method of TBP complexing extractant.

[0028] In this embodiment, a reuse method of TBP complexing extractant is disclosed, which comprises the following steps:

[0029] Step 1: The reused TBP complexing extractant is alkaline washed with 4-10% NaOH solution, the volume ratio of NaOH solution to organic phase is (0.5-2):1, 1-4 stages of countercurrent washing, the alkaline washing temperature is 20-50°C, and the washing time is 30-60 minutes, so as to remove the degradation products and impurities in the organic phase;

[0030] Step 2: The organic phase after alkaline washing is water washed with process water or desalted water, the volume ratio of process water or desalted water to organic phase is (0.5-2):1, 1-4 stages of countercurrent washing, the water washing temperature is 20-50°C, and the washing time is 30-60 minutes, until the organic phase is neutral;

[0031] Step 3: The organic phase after water washing is acidified by using 4 mol / L hydrochloric acid, the amount of hydrochloric acid is 30-100% of the volume of the organic phase, and the acidification time is 20-40 minutes, so as to restore the extraction performance;

[0032] Step 4: The acidified organic phase is reused to the production process of food-grade phosphoric acid by hydrochloric acid method.

[0033] Further, before reuse, a detection step is further included, which is that the regenerated organic phase is mixed with a solution containing phosphoric acid at a volume ratio of (3-5):1, the secondary countercurrent extraction rate of phosphoric acid is determined, if the extraction rate is ≥75%, it is determined to be qualified, and the unqualified product is subjected to steps 1-3 again.

[0034] Example 1

[0035] The present embodiment discloses a reuse method of TBP complexing extractant, which comprises the following steps:

[0036] Step 1: The reused TBP complexing extractant is alkaline washed with 4% NaOH solution, the volume ratio of NaOH solution to organic phase is 0.5:1, 1 stage of countercurrent washing, the alkaline washing temperature is 20°C, and the washing time is 30 minutes, so as to remove the degradation products and impurities in the organic phase;

[0037] Step 2: The organic phase after alkaline washing is water washed with process water or desalted water, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1 stage of countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes, until the organic phase is neutral;

[0038] Step 3, the organic phase after water washing is acidified by using 4 mol / L hydrochloric acid, the amount of hydrochloric acid is 30% of the volume of the organic phase, and the acidification time is 20 minutes to restore the extraction performance;

[0039] Step 4, the acidified organic phase is reused to the food-grade phosphoric acid production process by the hydrochloric acid method.

[0040] Further, before reuse, a detection step is further included, which is that the regenerated organic phase is mixed with a solution containing phosphoric acid at a volume ratio of 3:1 to determine the secondary countercurrent extraction rate of phosphoric acid, and if the extraction rate is ≥75%, it is determined to be qualified, and the unqualified product is reprocessed from step 1 to step 3.

[0041] Example 2

[0042] The embodiment discloses a reuse method of TBP complexing extractant, which comprises the following steps:

[0043] Step 1, the reused TBP complexing extractant is alkali washed by using 7% NaOH solution, the volume ratio of NaOH solution to organic phase is 0.5:1, 1-stage countercurrent washing, the alkali washing temperature is 20°C, and the washing time is 20 minutes to remove the degradation products and impurities in the organic phase;

[0044] Step 2, the organic phase after alkali washing is water washed by using process water or desalted water, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes until the organic phase is neutral;

[0045] Step 3, the organic phase after water washing is acidified by using 4 mol / L hydrochloric acid, the amount of hydrochloric acid is 30% of the volume of the organic phase, and the acidification time is 20 minutes to restore the extraction performance;

[0046] Step 4, the acidified organic phase is reused to the food-grade phosphoric acid production process by the hydrochloric acid method.

[0047] Further, before reuse, a detection step is further included, which is that the regenerated organic phase is mixed with a solution containing phosphoric acid at a volume ratio of 3:1 to determine the secondary countercurrent extraction rate of phosphoric acid, and if the extraction rate is ≥75%, it is determined to be qualified, and the unqualified product is reprocessed from step 1 to step 3.

[0048] Example 3

[0049] The embodiment discloses a reuse method of TBP complexing extractant, which comprises the following steps:

[0050] Step 1, using 10% NaOH solution to alkaline wash the recycled TBP complexing extractant, the volume ratio of NaOH solution to organic phase is 0.5:1, 1-stage countercurrent washing, the alkaline washing temperature is 20°C, and the washing time is 20 minutes, to remove the degradation products and impurities in the organic phase;

[0051] Step 2, using process water or desalted water to water wash the organic phase after alkaline washing, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes, until the organic phase is neutral;

[0052] Step 3, using 4 mol / L hydrochloric acid to acidify the organic phase after water washing, the hydrochloric acid dosage is 30% of the volume of the organic phase, and the acidification time is 20 minutes, to restore the extraction performance;

[0053] Step 4, recycling the acidified organic phase to the hydrochloric acid method food-grade phosphoric acid production process.

[0054] Further, before recycling, a detection step is further included, which is: mixing the regenerated organic phase with a solution containing phosphoric acid at a volume ratio of 3:1, determining the secondary countercurrent extraction rate of phosphoric acid, and if the extraction rate is ≥75%, it is determined to be qualified, and the unqualified product is reprocessed from step 1 to step 3.

[0055] Example 4

[0056] The embodiment discloses a recycling method of TBP complexing extractant, including the following steps:

[0057] Step 1, using 4% NaOH solution to alkaline wash the recycled TBP complexing extractant, the volume ratio of NaOH solution to organic phase is 1:1, 1-stage countercurrent washing, the alkaline washing temperature is 20°C, and the washing time is 20 minutes, to remove the degradation products and impurities in the organic phase;

[0058] Step 2, using process water or desalted water to water wash the organic phase after alkaline washing, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes, until the organic phase is neutral;

[0059] Step 3, using 4 mol / L hydrochloric acid to acidify the organic phase after water washing, the hydrochloric acid dosage is 30% of the volume of the organic phase, and the acidification time is 20 minutes, to restore the extraction performance;

[0060] Step 4, recycling the acidified organic phase to the hydrochloric acid method food-grade phosphoric acid production process.

[0061] Further, before reuse, a detection step is further included, which is: mixing the regenerated organic phase with a solution containing phosphoric acid at a volume ratio of 3:1, determining the secondary countercurrent extraction rate of phosphoric acid, if the extraction rate is ≥75%, it is determined to be qualified, and unqualified products are reprocessed from step 1 to step 3.

[0062] Example 5

[0063] The embodiment discloses a reuse method of TBP complexing extractant, comprising the following steps:

[0064] Step 1, using 4% NaOH solution to alkali wash the reused TBP complexing extractant, the volume ratio of NaOH solution to organic phase is 2:1, 1-stage countercurrent washing, the alkali washing temperature is 20°C, and the washing time is 20 minutes, so as to remove the degradation products and impurities in the organic phase;

[0065] Step 2, using process water or desalted water to water wash the organic phase after alkali washing, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes, so as to make the organic phase neutral;

[0066] Step 3, using 4 mol / L hydrochloric acid to acidify the organic phase after water washing, the amount of hydrochloric acid is 30% of the volume of the organic phase, and the acidification time is 20 minutes, so as to restore the extraction performance;

[0067] Step 4, recycling the acidified organic phase to the hydrochloric acid method food-grade phosphoric acid production process.

[0068] Further, before reuse, a detection step is further included, which is: mixing the regenerated organic phase with a solution containing phosphoric acid at a volume ratio of 3:1, determining the secondary countercurrent extraction rate of phosphoric acid, if the extraction rate is ≥75%, it is determined to be qualified, and unqualified products are reprocessed from step 1 to step 3.

[0069] Example 6

[0070] The embodiment discloses a reuse method of TBP complexing extractant, comprising the following steps:

[0071] Step 1, using 4% NaOH solution to alkali wash the reused TBP complexing extractant, the volume ratio of NaOH solution to organic phase is 0.5:1, 1-stage countercurrent washing, the alkali washing temperature is 35°C, and the washing time is 45 minutes, so as to remove the degradation products and impurities in the organic phase;

[0072] Step 2, using process water or desalted water to water wash the organic phase after alkali washing, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes, so as to make the organic phase neutral;

[0073] Step 3, the organic phase after water washing is acidified by using 4 mol / L hydrochloric acid, the amount of hydrochloric acid is 30% of the volume of the organic phase, and the acidification time is 20 minutes to restore the extraction performance;

[0074] Step 4, the acidified organic phase is reused in the food-grade phosphoric acid production process by the hydrochloric acid method.

[0075] Further, before reuse, a detection step is further included, which is that the regenerated organic phase is mixed with a solution containing phosphoric acid at a volume ratio of 3:1 to determine the secondary countercurrent extraction rate of phosphoric acid, and if the extraction rate is ≥75%, it is determined to be qualified, and unqualified products are reprocessed from step 1 to step 3.

[0076] Example 7

[0077] The embodiment discloses a reuse method of TBP complexing extractant, including the following steps:

[0078] Step 1, the reused TBP complexing extractant is alkali washed by using 4% NaOH solution, the volume ratio of NaOH solution to organic phase is 0.5:1, 1-stage countercurrent washing, the alkali washing temperature is 50°C, and the washing time is 60 minutes to remove degradation products and impurities in the organic phase;

[0079] Step 2, the organic phase after alkali washing is water washed by using process water or desalted water, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes until the organic phase is neutral;

[0080] Step 3, the organic phase after water washing is acidified by using 4 mol / L hydrochloric acid, the amount of hydrochloric acid is 30% of the volume of the organic phase, and the acidification time is 20 minutes to restore the extraction performance;

[0081] Step 4, the acidified organic phase is reused in the food-grade phosphoric acid production process by the hydrochloric acid method.

[0082] Further, before reuse, a detection step is further included, which is that the regenerated organic phase is mixed with a solution containing phosphoric acid at a volume ratio of 3:1 to determine the secondary countercurrent extraction rate of phosphoric acid, and if the extraction rate is ≥75%, it is determined to be qualified, and unqualified products are reprocessed from step 1 to step 3.

[0083] Example 8

[0084] The embodiment discloses a reuse method of TBP complexing extractant, including the following steps:

[0085] Step 1, using 4% NaOH solution to alkali wash the recycled TBP complexing extractant, the volume ratio of NaOH solution to organic phase is 0.5:1, 1-stage countercurrent washing, the alkali washing temperature is 20°C, and the washing time is 30 minutes, to remove the degradation products and impurities in the organic phase;

[0086] Step 2, using process water or desalted water to water wash the organic phase after alkali washing, the volume ratio of process water or desalted water to organic phase is 1:1, 1-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes, until the organic phase is neutral;

[0087] Step 3, using 4 mol / L hydrochloric acid to acidify the organic phase after water washing, the hydrochloric acid dosage is 30% of the volume of the organic phase, the acidification time is 20 minutes, and the extraction performance is restored;

[0088] Step 4, recycling the acidified organic phase to the hydrochloric acid method food-grade phosphoric acid production process.

[0089] Further, before recycling, a detection step is further included, that is, mixing the regenerated organic phase with a solution containing phosphoric acid at a volume ratio of 3:1, determining the secondary countercurrent extraction rate of phosphoric acid, if the extraction rate is ≥75%, it is determined to be qualified, and the unqualified product is reprocessed from step 1 to step 3.

[0090] Example 9

[0091] The embodiment discloses a recycling method of TBP complexing extractant, including the following steps:

[0092] Step 1, using 4% NaOH solution to alkali wash the recycled TBP complexing extractant, the volume ratio of NaOH solution to organic phase is 0.5:1, 1-stage countercurrent washing, the alkali washing temperature is 20°C, and the washing time is 30 minutes, to remove the degradation products and impurities in the organic phase;

[0093] Step 2, using process water or desalted water to water wash the organic phase after alkali washing, the volume ratio of process water or desalted water to organic phase is 2:1, 1-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes, until the organic phase is neutral;

[0094] Step 3, using 4 mol / L hydrochloric acid to acidify the organic phase after water washing, the hydrochloric acid dosage is 30% of the volume of the organic phase, the acidification time is 20 minutes, and the extraction performance is restored;

[0095] Step 4, recycling the acidified organic phase to the hydrochloric acid method food-grade phosphoric acid production process.

[0096] Further, before reuse, a detection step is further included, which is: mixing the regenerated organic phase with a solution containing phosphoric acid at a volume ratio of 3:1, determining the secondary countercurrent extraction rate of phosphoric acid, if the extraction rate is ≥75%, it is determined to be qualified, and unqualified products are reprocessed from step 1 to step 3.

[0097] Example 10

[0098] The embodiment discloses a reuse method of TBP complexing extractant, comprising the following steps:

[0099] Step 1, using 4% NaOH solution to alkali wash the reused TBP complexing extractant, the volume ratio of NaOH solution to organic phase is 0.5:1, 1-stage countercurrent washing, the alkali washing temperature is 20°C, and the washing time is 30 minutes, so as to remove the degradation products and impurities in the organic phase;

[0100] Step 2, using process water or desalted water to water wash the organic phase after alkali washing, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing, the water washing temperature is 35°C, and the washing time is 45 minutes, until the organic phase is neutral;

[0101] Step 3, using 4 mol / L hydrochloric acid to acidify the organic phase after water washing, the hydrochloric acid amount is 30% of the volume of the organic phase, the acidification time is 20 minutes, and the extraction performance is recovered;

[0102] Step 4, the acidified organic phase is reused to the food-grade phosphoric acid production process by hydrochloric acid method.

[0103] Further, before reuse, a detection step is further included, which is: mixing the regenerated organic phase with a solution containing phosphoric acid at a volume ratio of 3:1, determining the secondary countercurrent extraction rate of phosphoric acid, if the extraction rate is ≥75%, it is determined to be qualified, and unqualified products are reprocessed from step 1 to step 3.

[0104] Example 11

[0105] The embodiment discloses a reuse method of TBP complexing extractant, comprising the following steps:

[0106] Step 1, using 4% NaOH solution to alkali wash the reused TBP complexing extractant, the volume ratio of NaOH solution to organic phase is 0.5:1, 1-stage countercurrent washing, the alkali washing temperature is 20°C, and the washing time is 30 minutes, so as to remove the degradation products and impurities in the organic phase;

[0107] Step 2, using process water or desalted water to water wash the organic phase after alkali washing, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing, the water washing temperature is 50°C, and the washing time is 60 minutes, until the organic phase is neutral;

[0108] Step 3, the organic phase after water washing is acidified by using 4 mol / L hydrochloric acid, the amount of hydrochloric acid is 30% of the volume of the organic phase, and the acidification time is 20 minutes to restore the extraction performance;

[0109] Step 4, the acidified organic phase is reused in the food-grade phosphoric acid production process by the hydrochloric acid method.

[0110] Further, before reuse, a detection step is further included, which is that the regenerated organic phase is mixed with a solution containing phosphoric acid at a volume ratio of 3:1 to determine the secondary countercurrent extraction rate of phosphoric acid, and if the extraction rate is ≥75%, it is determined to be qualified, and unqualified products are reprocessed from step 1 to step 3.

[0111] Example 12

[0112] The embodiment discloses a reuse method of TBP complexing extractant, including the following steps:

[0113] Step 1, the reused TBP complexing extractant is alkali washed by using 4% NaOH solution, the volume ratio of NaOH solution to organic phase is 0.5:1, 1-stage countercurrent washing, the alkali washing temperature is 20°C, and the washing time is 30 minutes to remove degradation products and impurities in the organic phase;

[0114] Step 2, the organic phase after alkali washing is water washed by using process water or desalted water, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes until the organic phase is neutral;

[0115] Step 3, the organic phase after water washing is acidified by using 4 mol / L hydrochloric acid, the amount of hydrochloric acid is 100% of the volume of the organic phase, and the acidification time is 40 minutes to restore the extraction performance;

[0116] Step 4, the acidified organic phase is reused in the food-grade phosphoric acid production process by the hydrochloric acid method.

[0117] Further, before reuse, a detection step is further included, which is that the regenerated organic phase is mixed with a solution containing phosphoric acid at a volume ratio of 3:1 to determine the secondary countercurrent extraction rate of phosphoric acid, and if the extraction rate is ≥75%, it is determined to be qualified, and unqualified products are reprocessed from step 1 to step 3.

[0118] Example 13

[0119] The embodiment discloses a reuse method of TBP complexing extractant, including the following steps:

[0120] Step 1, using 4% NaOH solution to alkaline wash the recycled TBP complexing extractant, the volume ratio of NaOH solution to organic phase is 0.5:1, 2-stage countercurrent washing, the alkaline washing temperature is 20°C, and the washing time is 30 minutes, to remove the degradation products and impurities in the organic phase;

[0121] Step 2, using process water or desalted water to water wash the organic phase after alkaline washing, the volume ratio of process water or desalted water to organic phase is 0.5:1, 2-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes, until the organic phase is neutral;

[0122] Step 3, using 4 mol / L hydrochloric acid to acidify the organic phase after water washing, the hydrochloric acid dosage is 30% of the volume of the organic phase, the acidification time is 20 minutes, and the extraction performance is restored;

[0123] Step 4, recycling the acidified organic phase to the hydrochloric acid method food-grade phosphoric acid production process.

[0124] Further, before recycling, a detection step is further included, which is: mixing the regenerated organic phase with a solution containing phosphoric acid at a volume ratio of 3:1, determining the secondary countercurrent extraction rate of phosphoric acid, and if the extraction rate is ≥75%, it is determined to be qualified, and the unqualified product is reprocessed from step 1 to step 3.

[0125] Example 14

[0126] The embodiment discloses a recycling method of TBP complexing extractant, comprising the following steps:

[0127] Step 1, using 4% NaOH solution to alkaline wash the recycled TBP complexing extractant, the volume ratio of NaOH solution to organic phase is 0.5:1, 4-stage countercurrent washing, the alkaline washing temperature is 20°C, and the washing time is 30 minutes, to remove the degradation products and impurities in the organic phase;

[0128] Step 2, using process water or desalted water to water wash the organic phase after alkaline washing, the volume ratio of process water or desalted water to organic phase is 0.5:1, 4-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes, until the organic phase is neutral;

[0129] Step 3, using 4 mol / L hydrochloric acid to acidify the organic phase after water washing, the hydrochloric acid dosage is 30% of the volume of the organic phase, the acidification time is 20 minutes, and the extraction performance is restored;

[0130] Step 4, recycling the acidified organic phase to the hydrochloric acid method food-grade phosphoric acid production process.

[0131] Further, before reuse, a detection step is further included, which is: mixing the regenerated organic phase with a solution containing phosphoric acid at a volume ratio of 3:1, determining the secondary countercurrent extraction rate of phosphoric acid, if the extraction rate is ≥75%, it is determined to be qualified, and unqualified products are reprocessed from step 1 to step 3.

[0132] Example 15

[0133] The embodiment discloses a reuse method of TBP complexing extractant, comprising the following steps:

[0134] Step 1, using 4% NaOH solution to alkali wash the reused TBP complexing extractant, the volume ratio of NaOH solution to organic phase is 0.5:1, 1-stage countercurrent washing, the alkali washing temperature is 20°C, and the washing time is 30 minutes, so as to remove the degradation products and impurities in the organic phase;

[0135] Step 2, using process water or desalted water to water wash the organic phase after alkali washing, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes, so as to make the organic phase neutral;

[0136] Step 3, using 4 mol / L hydrochloric acid to acidify the organic phase after water washing, the hydrochloric acid amount is 30% of the volume of the organic phase, and the acidification time is 20 minutes, so as to restore the extraction performance;

[0137] Step 4, recycling the acidified organic phase to the food-grade phosphoric acid production process by hydrochloric acid method.

[0138] Further, before reuse, a detection step is further included, which is: mixing the regenerated organic phase with a solution containing phosphoric acid at a volume ratio of 3:1, determining the secondary countercurrent extraction rate of phosphoric acid, if the extraction rate is ≥75%, it is determined to be qualified, and unqualified products are reprocessed from step 1 to step 3.

[0139] Example 16

[0140] The embodiment discloses a reuse method of TBP complexing extractant, comprising the following steps:

[0141] Step 1, using 4% NaOH solution to alkali wash the reused TBP complexing extractant, the volume ratio of NaOH solution to organic phase is 0.5:1, 1-stage countercurrent washing, the alkali washing temperature is 20°C, and the washing time is 30 minutes, so as to remove the degradation products and impurities in the organic phase;

[0142] Step 2, using process water or desalted water to water wash the organic phase after alkali washing, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing, the water washing temperature is 20°C, and the washing time is 30 minutes, so as to make the organic phase neutral;

[0143] Step 3, the organic phase after water washing is acidified by using 2 mol / L hydrochloric acid, the amount of hydrochloric acid is 30% of the volume of the organic phase, and the acidification time is 20 minutes to restore the extraction performance;

[0144] Step 4, the acidified organic phase is reused in the hydrochloric acid method food-grade phosphoric acid production process.

[0145] Further, before reuse, a detection step is further included, which is that the regenerated organic phase is mixed with a phosphoric acid-containing solution at a volume ratio of 5:1 to determine the phosphoric acid secondary countercurrent extraction rate, and if the extraction rate is ≥75%, it is determined to be qualified, and unqualified products are reprocessed from step 1 to step 3.

[0146] Comparative Example 1

[0147] A reuse method of TBP complexing extractant, which adopts water washing method, only uses process water or desalted water to wash the organic phase after alkaline washing, the volume ratio of process water or desalted water to organic phase is 0.5:1, and 2-stage countercurrent washing is performed.

[0148] Comparative Example 2

[0149] A reuse method of TBP complexing extractant, which includes the following steps:

[0150] Step 1, the reused TBP complexing extractant is alkaline washed by using 4% NaOH solution, the volume ratio of NaOH solution to organic phase is 0.5:1, 1-stage countercurrent washing is performed, the alkaline washing temperature is 20°C, and the washing time is 30 minutes to remove degradation products and impurities in the organic phase;

[0151] Step 2, the organic phase after alkaline washing is water washed by using process water or desalted water, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing is performed, the water washing temperature is 20°C, and the washing time is 30 minutes until the organic phase is neutral;

[0152] Step 3, the organic phase is reused in the hydrochloric acid method food-grade phosphoric acid production process.

[0153] Comparative Example 3

[0154] A reuse method of TBP complexing extractant, which includes the following steps:

[0155] Step 1, the organic phase is water washed by using process water or desalted water, the volume ratio of process water or desalted water to organic phase is 0.5:1, 1-stage countercurrent washing is performed, the water washing temperature is 20°C, and the washing time is 30 minutes until the organic phase is neutral;

[0156] Step 2, the organic phase after water washing is acidified by using 2 mol / L hydrochloric acid, the amount of hydrochloric acid is 30% of the volume of the organic phase, and the acidification time is 20 minutes to restore the extraction performance;

[0157] Step 3, the acidified organic phase is recycled to the hydrochloric acid method food-grade phosphoric acid production process.

[0158] Performance test

[0159] The recycling method of the above examples 1-16 and comparative examples 1-3 is tested, and the extraction rate of the regenerated TBP complex extractant is tested, and the method is as follows:

[0160] Take 50 mL of simulated solution (containing H3PO4 20wt%, HCl 5wt%, simulating the iron removal dilute phosphoric acid in the production of hydrochloric acid method phosphoric acid) and 50 mL of regenerated TBP complex extractant (1:1) into a separatory funnel, and place it in a constant temperature water bath oscillator, oscillate at 25°C for 10 minutes. Stand for 10 minutes, separate the aqueous phase (raffinate) and organic phase.

[0161] Take 10 mL of raffinate, add 50 mL of deionized water, and add 2 drops of phenolphthalein indicator.

[0162] Titrate with 0.1 mol / L NaOH standard solution to pink end point (pH about 8.3), record the volume of NaOH consumed (V1).

[0163] The phosphoric acid concentration of the original simulated solution is determined by the same method (the volume of NaOH consumed V0).

[0164] Calculate the extraction rate:

[0165] Extraction rate (%) = (1-V0 / V1)*100%.

[0166] The results are shown in the following table:

[0167] Extraction rate Control group (TBP compound extractant without regeneration) 56.5 Blank group (TBP compound extractant is not used) 83.3 Example 1 82.1 Example 2 82.4 Example 3 82.3 Example 4 82.2 Example 5 82.2 Example 6 82.2 Example 7 82.3 Example 8 82.2 Example 9 82.4 Example 10 82.4 Example 11 82.5 Example 12 82.3 Example 13 82.4 Example 14 82.7 Example 15 82.2 Example 16 82.0 Comparative Example 1 64.5 Comparative Example 2 76.1 Comparative Example 3 75.7

[0168] From the above table data, it can be seen that the color of the TBP complex extractant deepens after a long time, and the extraction rate decreases significantly. In production, the organic phase is washed with 4%-10% NaOH solution, 1-4 stage countercurrent washing, and the organic phase is recycled after washing. The color of the organic phase is clear, and the organic phase after washing is acidified with 2-4 mol / L hydrochloric acid to achieve the extraction effect. The recycling method of the present application significantly improves the regeneration efficiency of the TBP complex extractant, and is conducive to reducing the production cost of hydrochloric acid method food-grade phosphoric acid. It has important significance for the industrialization and continuous production of hydrochloric acid method food-grade phosphoric acid.

[0169] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, but as long as the scope of the claims of the present application is within the scope of the patent law.

Claims

1. A method for reusing a compound extractant of food-grade TBP phosphate obtained by hydrochloric acid extraction, characterized in that, Includes the following steps: Step 1: Use NaOH solution to wash the recycled TBP compound extractant with alkaline solution, and perform 1-4 stages of countercurrent washing to remove degradation products and impurities from the organic phase; Step 2: Wash the organic phase after alkaline washing with process water or demineralized water using countercurrent washing stages 1-4 until the organic phase is neutral. Step 3: Acidify the washed organic phase with hydrochloric acid to restore extraction performance; Step 4: The acidified organic phase is recycled into the hydrochloric acid process for producing food-grade phosphoric acid.

2. The method for reusing the compound extractant of food-grade TBP phosphate using the hydrochloric acid method according to claim 1, characterized in that, In step 1, the reused TBP compound extractant is washed with 4-10% NaOH solution.

3. The method for reusing the compound extractant of food-grade TBP phosphate using the hydrochloric acid method according to claim 2, characterized in that, In step 1, the volume ratio of the NaOH solution to the organic phase is (0.5~2):

1.

4. The method for reusing the compound extractant of food-grade TBP phosphate using the hydrochloric acid method according to claim 3, characterized in that, In step 1, the alkaline washing temperature is 20~50°C and the washing time is 30~60 minutes.

5. The method for reusing the compound extractant of food-grade TBP phosphate using the hydrochloric acid method according to claim 1, characterized in that, In step 2, the volume ratio of the process water or desalinated water to the organic phase is (0.5~2):

1.

6. The method for reusing the compound extractant of food-grade TBP phosphate using the hydrochloric acid method according to claim 5, characterized in that, In step 2, the water washing temperature is 20~50°C and the washing time is 30~60 minutes.

7. The method for reusing the compound extractant of food-grade TBP phosphate using the hydrochloric acid method according to claim 1, characterized in that, In both steps 1 and 2, the washing process uses a two-stage countercurrent washing process.

8. The method for reusing the compound extractant of food-grade TBP phosphate in the hydrochloric acid process according to claim 1, characterized in that, In step 3, the organic phase after water washing is acidified using 2-4 mol / L hydrochloric acid.

9. The method for reusing the compound extractant of food-grade TBP phosphate in the hydrochloric acid process according to claim 8, characterized in that, In step 3, the amount of hydrochloric acid used is 30-100% of the volume of the organic phase, and the acidification time is 20-40 minutes.

10. The method for reusing the compound extractant of food-grade TBP phosphate using the hydrochloric acid method according to claim 1, characterized in that, In step 4, before reuse, a detection step is also included. The detection step is as follows: take the regenerated organic phase and the phosphoric acid-containing solution and mix them at a volume ratio of (3~5):

1. Measure the secondary countercurrent extraction rate of phosphoric acid. If the extraction rate is ≥75%, it is judged to be qualified. Unqualified products are repeated in steps 1 to 3.