Method for recovering glyphosate from glyphosate acid mother liquor

Abstract

The invention provides a method for recovering glyphosate from a glyphosate acid mother liquor, which comprises the following steps: concentration of the glyphosate acid mother liquor: heating and concentrating the glyphosate acid mother liquor, and carrying out solid-liquid separation after the concentration is finished to obtain triethylamine hydrochloride and a concentrated solution; adhering and separating out glyphosate: adding a flocculating agent into the concentrated solution, stirring, settling, and carrying out solid-liquid separation to recover a precipitate; and glyphosate recovery: adding a deflocculating agent into the sediment, stirring, carrying out solid-liquid separation, and washing and drying the recovered solid to obtain the glyphosate active compound. According to the method, the glyphosate mother liquor difficult to separate is subjected to three-step treatment including concentration treatment, flocculation and deflocculation, efficient recovery of glyphosate is achieved, the purity of the obtained glyphosate product can reach 70% or above, the recovery rate reaches 60% or above, a flocculating agent and a deflocculating agent can be recycled, and the method is suitable for industrial production. And a new method is provided for resource recovery of the glyphosate acid mother liquor.

Description

Technical Field

[0001] The invention belongs to the technical field of glyphosate production, and particularly relates to a method for recovering glyphosate from glyphosate acid mother liquor. Background Art

[0002] Glyphosate, chemically known as N-(phosphomethyl)glycine, is an organophosphine herbicide with excellent properties such as high efficiency, low toxicity, broad spectrum, lethality, and non-selectivity. It is widely used in orchards, woodlands, recreational areas, farmlands, and other places to control various weeds. Glyphosate is currently the most widely used herbicide. According to statistics, every ton of glyphosate produced will produce about 3.5 tons of glyphosate acid mother liquor, which contains 1-3% glyphosate, 1-2% glycine, 1-2% glyphosate, 1-10% sodium chloride, 20-30% triethylamine hydrochloride, etc. At present, the glyphosate mother liquor is mostly treated by concentrated incineration and wet oxidation in industry. The high-value phosphide is difficult to recycle, and the phosphorus-containing solid waste generated is also a problem that needs to be dealt with urgently. At present, there are certain methods for recycling glyphosate from glyphosate mother liquor, such as: Patent CN113072580A discloses a method for recycling glyphosate from glyphosate acid mother liquor of glycine method, by multi-stage concentration of acid mother liquor and secondary hydrolysis, although glyphosate can be effectively recovered, the operation steps are relatively cumbersome, and the accumulation of other impurities will affect the glyphosate produced by hydrolysis; Patent CN101704841B discloses a method for recycling glyphosate mother liquor, by adding alkali to neutralize the acid mother liquor, then multi-stage concentration and desalination, and adjusting the pH of the remaining mother liquor to prepare glyphosate aqueous solution, this method does not effectively recover glyphosate from the mother liquor, and the quality of the subsequent glyphosate aqueous solution is unstable, which may further pollute the natural environment. Therefore, it is of great research significance to further explore efficient and simple methods for recycling glyphosate mother liquor. Summary of the invention

[0003] The present invention provides a method for recovering glyphosate from a glyphosate acid mother liquor. In the embodiment of the present invention, the glyphosate acid mother liquor is the acidic filtrate remaining after collecting the original drug in the glyphosate production process, and comprises the following steps: adding the glyphosate acid mother liquor into a reactor, concentrating and separating the glyphosate acid mother liquor, collecting the glyphosate concentrated solution, adding a flocculant into the concentrated solution to fully precipitate the glyphosate in the system, then performing solid-liquid separation, and then adding a deflocculating agent into the system to recover the glyphosate. The present invention adopts a three-step treatment process based on concentration, flocculation and deflocculation of the glyphosate acid mother liquor, which can realize the efficient, rapid and selective precipitation of glyphosate in the glyphosate mother liquor. The designed separation process is simple and easy to operate. The selected flocculants and deflocculating agents can be recycled and reused, and have certain economic and environmental benefits.

[0004] In view of the above problems, the present invention provides a method for recovering glyphosate from glyphosate acid mother liquor. The process comprises concentrating the glyphosate acid mother liquor, enriching the glyphosate, and then diluting the glyphosate, adding a flocculant thereto, allowing the glyphosate to be fully separated and attached, and then performing solid-liquid separation and adding a deflocculating agent to recover the glyphosate.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows: (1) Concentration of glyphosate acid mother liquor: Add a certain amount of glyphosate acid mother liquor into the reactor, increase the temperature to concentrate it, and perform solid-liquid separation after concentration to obtain triethylamine hydrochloride and concentrated solution.

[0006] (2) Glyphosate adhesion and precipitation: Add flocculant to the concentrated solution, stir, settle, separate the solid and liquid, and recover the sediment.

[0007] (3) Glyphosate recovery: add a deflocculant to the sediment, stir, separate the solid and liquid, wash and dry the recovered solid to obtain glyphosate technical.

[0008] In the above scheme, the glyphosate acid mother liquor is the acidic filtrate remaining after collecting the original drug during the glyphosate production process.

[0009] In the above scheme, the glyphosate content of the acidic mother solution is 0.8%-2%, and the pH is 0.2-1.6.

[0010] In the above scheme, the concentration method is atmospheric pressure concentration or reduced pressure concentration.

[0011] In the above scheme, the stirring time during the concentration is 1-180 min, and the stirring speed is 1-500 r / min.

[0012] In the above scheme, the temperature during atmospheric concentration is 105-130°C, and the temperature during reduced pressure concentration is 60-80°C.

[0013] In the above scheme, the pressure during the reduced pressure concentration is -0.01~-0.09MPa.

[0014] In the above scheme, the mass ratio of the concentrate to the glyphosate acid mother solution is 0.2-0.5:1, preferably 0.25-0.4:1. In the present invention, the ratio of the concentrate (i.e., the glyphosate content in the concentrate) is determined: if the concentration ratio is too low or not concentrated, the required amount of flocculant is high and the recovery efficiency is low; if the concentration degree is high, the glyphosate loss is large and the recovery is difficult.

[0015] In the above scheme, the flocculant is a common inorganic flocculant and an organic polymer flocculant, including but not limited to any one of polyaluminium chloride, polyaluminium sulfate, polyferric chloride, polyferric sulfate, aminated chitosan-based flocculant, cellulose-based flocculant, starch-based flocculant, etc.

[0016] In the above scheme, the content of the flocculant is 1%-30%, preferably 5%-20%; the dosage is 1%-30% of the mass of the concentrated liquid, preferably 10%-25%.

[0017] In the above scheme, the stirring method is magnetic stirring, electric stirring, etc.; the stirring time is 30-600min, and the stirring speed is 50-600r / min.

[0018] In the above scheme, the deflocculating agent includes but is not limited to any one or more of common organic and inorganic deflocculating agents such as citrate, tartrate, phosphate, carbonate, glycine, etc.

[0019] In the above scheme, the citrate, tartrate, phosphate, carbonate, and glycine salt include any one or more of common soluble salts such as sodium salt, potassium salt, magnesium salt, and ammonium salt.

[0020] In the above scheme, the content of the deflocculating agent is 1%-25%, preferably 8%-15%; the dosage is 1%-50% of the mass of the concentrated liquid, preferably 20%-40%.

[0021] The flocculant is used to separate glyphosate from the mother liquor. The main components of the precipitated solid are glyphosate, triethylamine hydrochloride, sodium chloride, glycine, glyphosate and other substances. The system is flocculent and it is difficult to remove impurities by washing to obtain the glyphosate product. It needs to be deflocculated to remove the complex state of each substance, and then washed to obtain glyphosate. Comparative Example 2 has a case where no deflocculating agent is used.

[0022] In the above scheme, the drying method is air drying, freeze drying, reduced pressure drying, spray drying, etc.

[0023] The present invention aims at the glyphosate mother liquor which is difficult to separate, and realizes the efficient recovery of glyphosate through the three-step treatment of concentration treatment, flocculation and deflocculation. The purity of the obtained glyphosate product can reach more than 70%, and the recovery rate reaches more than 60%. Moreover, the flocculant and the deflocculating agent can be recycled and reused, which provides a new method for the resource recovery of glyphosate acid mother liquor.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention effectively realizes the recycling and utilization of glyphosate, and at the same time, the purity and recovery rate of the recovered glyphosate are high, the operation is simple, less materials are involved, and it is easy to carry out industrial promotion; (2) The operation steps designed by the present invention are simple and easy to operate, do not involve complicated reactions, and the used reagents can be recycled and reused, with low recycling costs, and have certain environmental and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the infrared spectrum of the glyphosate sample and glyphosate standard recovered in Example 1. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] Examples 1-5 A method for recovering glyphosate from glyphosate acid mother liquor comprises the following steps: 16 kg of glyphosate acid mother liquor (glyphosate content 1.32%, pH 1.1) was added to a 20 L glass reactor and concentrated under reduced pressure to obtain 5.12 kg of condensate and 10.88 kg of mixed slurry. The mixed slurry was subjected to solid-liquid separation to obtain 4.58 kg of crystalline salt and 6.3 kg of concentrated liquid. After testing, the glyphosate content in the concentrated liquid was 3.28%.

[0028] Take 5 500ml flasks and number them 1#-5#, add 200g of the above concentrate thereto, and then add 10% polyaluminium chloride, 10% polyaluminium sulfate, 10% polyferric chloride, 10% polyferric sulfate, 40g of 10% aminated chitosan-based flocculant aqueous solution in sequence, stir at a fixed speed of 500rpm for 3h, let stand and settle for about 30min, and obtain flocculent agglomerates by solid-liquid separation; then add 60g of 10% sodium glycinate aqueous solution thereto respectively, stir for 30min, separate the solid and liquid, wash and dry, and obtain the recovered glyphosate sample. The recovery content and recovery rate indicators are shown in the table below.

[0029]

[0030] Figure 1 The infrared spectra of the glyphosate sample obtained in the example and the glyphosate standard are shown in Figure 2. The results show that the infrared spectra of the recovered glyphosate sample and the glyphosate standard are basically consistent.

[0031] Examples 6-10 A method for recovering glyphosate from glyphosate acid mother liquor comprises the following steps: Take 5 500ml flasks and number them 6#-10#, add 200g of the above concentrate thereto, then add 40g of 10% polyaluminium chloride aqueous solution respectively, stir at a fixed speed of 500rpm for 3h, let stand and settle for about 30min, and separate the solid and liquid to obtain flocculent agglomerates; then add 60g of 10% sodium tartrate, 10% sodium phosphate, 10% sodium hydrogen phosphate, 10% magnesium succinate, and 10% potassium glycinate aqueous solution respectively, stir for 30min, separate the solid and liquid, wash and dry, and obtain the recovered glyphosate sample. The recovery content and recovery rate indicators are shown in the table below.

[0032]

[0033] Examples 11-15 A method for recovering glyphosate from glyphosate acid mother liquor comprises the following steps: Take 5 500ml flasks and number them 11#-15#, add 200g of the above-mentioned concentrated solution thereto, and then add 20g, 60g of 5% polyaluminium chloride aqueous solution, 20g, 40g, 60g of 20% polyaluminium chloride aqueous solution respectively, stir at a fixed speed of 500rpm for 3h, let stand and settle for about 30min, and obtain flocculent agglomerates by solid-liquid separation; then add 60g of 10% sodium glycinate aqueous solution respectively, stir for 30min, separate the solid and liquid, wash and dry, and obtain the recovered glyphosate samples. The recovery content and recovery rate indicators are shown in the table below.

[0034]

[0035] Examples 16-20 A method for recovering glyphosate from glyphosate acid mother liquor comprises the following steps: Take 5 500ml flasks and number them 16#-20#, add 200g of the above concentrate therein, then add 40g of 10% polyaluminium chloride aqueous solution respectively, stir at a fixed speed of 500rpm for 3h, let stand and settle for about 30min, and obtain flocculent agglomerates by solid-liquid separation; then add 80g, 120g of 8% sodium glycinate aqueous solution, 40g, 80g, 120g of 15% sodium glycinate respectively, stir for 30min, separate the solid and liquid, wash and dry, and obtain the recovered glyphosate sample. The recovery content and recovery rate indicators are shown in the table below.

[0036]

[0037] Comparative Example 1 Take a 500ml flask and add 200g of the above concentrate, then add 40g of water, stir at a fixed speed of 500rpm for 3h, let it stand and settle for about 30min, separate the solid and liquid to obtain a small amount of solid, wash and dry, and obtain 0.36g of solid, with a glyphosate content of 6.27% and a recovery rate of 0.34%.

[0038] Comparative Example 2 Take a 500ml flask and add 200g of the above concentrate, then add 40g of 10% polyaluminium chloride aqueous solution, stir at a fixed speed of 500rpm for 3h, let it stand and settle for about 30min, separate the solid and liquid to obtain flocculent agglomerates, wash and dry to obtain 12.86g of solid, with a glyphosate content of 26.68% and a recovery rate of 52.3%.

[0039] Comparative Example 3 Take a 500ml flask and add 200g of the above concentrate, then add 60g of 10% sodium glycinate aqueous solution, stir at a fixed speed of 500rpm for 3h, let it stand and settle for about 30min, separate the solid and liquid to obtain a small amount of solid, wash and dry to obtain 1.68g of solid, with a glyphosate content of 5.66% and a recovery rate of 1.45%.

[0040] The above embodiments are only examples for clear explanation and are not intended to limit the implementation of the method. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here, so the obvious changes or modifications derived are still within the protection scope of the invention.

Claims

1. A method for recovering glyphosate from a glyphosate acid mother liquor, characterized in that: The steps include: (1) Concentration of glyphosate acid mother liquor: The glyphosate acid mother liquor is heated and concentrated, and after the concentration is completed, solid-liquid separation is performed to obtain triethylamine hydrochloride and a concentrated solution; (2) Glyphosate adhesion and precipitation: add flocculant to the concentrated solution, stir, settle, separate the solid and liquid, and recover the sediment; (3) Glyphosate recovery: add a deflocculant to the sediment, stir, separate the solid and liquid, wash and dry the recovered solid to obtain glyphosate technical.

2. The method for recovering glyphosate from glyphosate acid mother liquor according to claim 1, characterized in that: The glyphosate acid mother liquor is the acidic filtrate remaining after collecting the original drug in the glyphosate production process. The glyphosate content of the acidic mother liquor is 0.8%-2%, and the pH is 0.2-1.

6.

3. The method for recovering glyphosate from glyphosate acid mother liquor according to claim 1, characterized in that: The concentration method is atmospheric pressure concentration or reduced pressure concentration.

4. The method for recovering glyphosate from glyphosate acid mother liquor according to claim 1, characterized in that: During the concentration, the stirring time is 1-180 min, and the stirring speed is 1-500 r / min.

5. The method for recovering glyphosate from glyphosate acid mother liquor according to claim 1, characterized in that: The temperature during atmospheric pressure concentration is 105-130° C.; the temperature during reduced pressure concentration is 60-80° C., and the pressure during reduced pressure concentration is -0.01-0.09 MPa.

6. The method for recovering glyphosate from glyphosate acid mother liquor according to claim 1, characterized in that: The mass ratio of the concentrated solution to the glyphosate acid mother solution is 0.2-0.5:

1.

7. The method for recovering glyphosate from glyphosate acid mother liquor according to claim 1, characterized in that: The flocculants include inorganic flocculants and organic polymer flocculants, including any one or more of polyaluminium chloride, polyaluminium sulfate, polyferric chloride, polyferric sulfate, aminated chitosan-based flocculants, cellulose-based flocculants and starch-based flocculants; The content of the flocculant is 1%-30%, and the dosage is 1%-30% of the mass of the concentrated liquid.

8. The method for recovering glyphosate from glyphosate acid mother liquor according to claim 1, characterized in that: The stirring method is magnetic stirring and electric stirring; the stirring time is 30-600min, and the stirring speed is 50-600r / min.

9. The method for recovering glyphosate from glyphosate acid mother liquor according to claim 1, characterized in that: The deflocculating agent includes any one or more of citrate, tartrate, phosphate, carbonate and glycine; the content of the deflocculating agent is 1%-25%; and the dosage is 1%-50% of the mass of the concentrated liquid.

10. The method for recovering glyphosate from glyphosate acid mother liquor according to claim 1, characterized in that: The drying method is air drying, freeze drying, reduced pressure drying or spray drying.

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