Purification process and device of by-product ammonium chloride of industrial grade aminoacetic acid

Abstract

The present application relates to the technical field of industrial aminoacetic acid production, in particular to a kind of industrial aminoacetic acid by-product ammonium chloride purification process and device. First, the methanol mother liquor after separating aminoacetic acid is decolorized by activated carbon or amino multi-walled carbon tube, then continuously enters the beating kettle with by-product red ammonium chloride, is fully stirred and mixed, the slurry is continuously extracted into horizontal scraper centrifuge, and ammonium chloride wet product is separated, the separation filtrate is returned to rectification mother liquor pool, the filtrate normally enters methanol recovery and red ammonium chloride recovery process, and ammonium chloride wet product is dried in micro negative pressure in disc dryer, agricultural high-grade ammonium chloride can be produced. One is that the quality of aminoacetic acid by-product ammonium chloride can be improved from agricultural qualified product to high-quality product, two is that the method can improve the quality of ammonium chloride while intermittently recovering part of organic matter, three is that the methanol mother liquor generated by aminoacetic acid itself is used without changing or affecting the normal operation of aminoacetic acid.

Description

Technical Field

[0001] This invention belongs to the field of industrial-grade glycine production technology, and in particular relates to a process and apparatus for purifying ammonium chloride, a byproduct of industrial-grade glycine production. Background Technology

[0002] Glycoacetic acid, as an important fine chemical product, is widely used in pharmaceuticals, food, daily chemicals, and agriculture. Particularly in agriculture, it is the main raw material for the synthesis of glyphosate, the most widely used, highest-volume, and most active green herbicide globally. Glycoacetic acid synthesis includes the Strecker process, chloroacetic acid ammonolysis, the Hein process, and biosynthesis. Among these, only the Strecker process (a foreign process) and the chloroacetic acid ammonolysis process (a domestic process) have been industrialized. In my country, glycoacetic acid production uses the chloroacetic acid ammonolysis process, with water as a solvent and hexamethylenetetramine as a catalyst. Ammonia is passed through an aqueous solution of chloroacetic acid to produce glycoacetic acid and ammonium chloride. Glycoacetic acid is then obtained through methanol extraction, crystallization, and centrifugation. The methanol mother liquor from the centrifugation is recovered by distillation, and the residue in the distillation column is concentrated using a double-effect distillation process, crystallized until thickened, and centrifuged to obtain red ammonium chloride wet powder. Ammonium chloride filtrate is produced as a byproduct.

[0003] The production of 10,500 tons of industrial-grade glycine produces 10,500 tons of red ammonium chloride as a byproduct. This red ammonium chloride is yellowish in color and its quality grade only meets the standards for qualified agricultural-grade ammonium chloride (nitrogen content ≥24%, moisture ≤7%, sodium salt content ≤1.6%), with a selling price of approximately 50-100 yuan / ton. To further improve quality and efficiency, it is urgent to find a purification technology for this byproduct, ammonium chloride, to upgrade its quality from qualified agricultural-grade ammonium chloride to superior agricultural-grade ammonium chloride.

[0004] Patent CN114455607 discloses a method for purifying industrial by-product ammonium chloride. The method involves forming a suspension from an industrial by-product ammonium chloride solution, removing impurities from the suspension to form an aerosol, subjecting the aerosol to particle collision and coalescence treatment to form ammonium chloride crystals, and drying the ammonium chloride crystals to obtain reagent-grade anhydrous ammonium chloride. This method employs sublimation, pressurized particle collision treatment, and heat treatment processes, making the process lengthy and unsuitable for the industrial-scale purification of low-value-added by-products from the tens of thousands of tons of glycine.

[0005] As is known from existing technology, the profit margin of industrial-grade glycine is relatively low. For ammonium chloride, a byproduct of glycine with low added value, it is necessary to develop purification processes and equipment for high-quality ammonium chloride products for agricultural use, while also taking into account production costs. This requires continuous innovation and optimization, and the development of better industrial solutions. Summary of the Invention

[0006] In response to the mainstream industrialization route for ammonium chloride, a byproduct of glycine, this invention provides a purification process and apparatus for industrial-grade ammonium chloride, addressing issues such as low nitrogen content, yellow color, low selling price despite large quantities, small particle size, severe odor, and enrichment of organic amines in existing processes.

[0007] To achieve the above objectives, the present invention adopts the following process technology solution: (1) First, the methanol mother liquor after separating glycine is decolorized by activated carbon and / or aminated multi-walled carbon nanotubes; (2) Then, the by-product red ammonium chloride and aminated multi-walled carbon nanotubes are continuously fed into the pulping kettle in a certain proportion, and a certain amount of aminated multi-walled carbon nanotubes are added and thoroughly stirred and mixed. (3) The slurry obtained in step (2) is continuously collected and fed into a horizontal scraper centrifuge to separate the wet ammonium chloride. The separated filtrate is then returned to the methanol mother liquor in the distillation mother liquor pool in step (1). (4) The mother liquor is used to recover methanol through a distillation column and red ammonium chloride is recovered through double-effect concentration. The wet ammonium chloride is dried under slight negative pressure in a disc dryer to produce high-grade ammonium chloride for agricultural use.

[0008] Specifically, the methanol mother liquor contains (wt%): 60-63.5% methanol, 8-10% ammonium chloride, 15-18% water, 1-2% hexamethylenetetramine, 1-2% dichloroacetate, 1-2% iminodiacetic acid, and 1-2% ammonium acetate.

[0009] Activated carbon properties: 50~400 mesh, iodine adsorption value 900~1500mg / g, pH=7~10, caramel decolorization 80~130%, moisture content 1~3%.

[0010] In step (1), the ratio of activated carbon to methanol mother liquor (mass ratio) is 0.001 to 0.005:1.

[0011] In step (1), the amount of aminated multi-walled carbon nanotubes added is 0.01-1 wt% of the amount of methanol mother liquor, the decolorization temperature is 25-45℃, and the decolorization time is 10-50 min.

[0012] Specifically, the decolorized methanol mother liquor contains (wt%): 62-65% methanol, 9-11.5% ammonium chloride, 15-18% water, 0.5-1% hexamethylenetetramine, 0.5-1.2% dichloroacetic acid, 0.5-1.1% iminodiacetic acid, 0.5-1.3% ammonium acetate, and has a whiteness of 90-95%.

[0013] Specifically, the red ammonium chloride byproduct of glycine contains (wt%): nitrogen content 23-24.5%, moisture 3-5%, organic matter 6-8%, and whiteness 50-60%.

[0014] Specifically, in step (2), the amount of aminated multi-walled carbon nanotubes added is 0.01-1 wt% of the methanol mother liquor, the decolorization temperature is 25-45℃, and the decolorization time is 10-50 min. The aminated multi-walled carbon nanotubes were purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0015] Specifically, the ratio of crude red ammonium chloride to decolorized methanol mother liquor is 1:1 to 1:10, and the mixing and pulping time is 15 to 60 minutes. Specifically, the drying temperature of the disc dryer is 80 to 90℃, the vacuum degree is -0.05 MPa to -0.01 MPa, the stirring speed is 10 to 60 rpm, the drying time is 10 to 30 minutes, the number of drying discs is 15 to 22, and the number of cooling discs is 1 to 10.

[0016] By adopting the above scheme, high-quality ammonium chloride for agricultural use can be produced. The specific composition is: pure ammonium chloride with an inorganic nitrogen content of 25.4-26%, a moisture content of 0.3-0.5%, and a whiteness of 85-90%.

[0017] To achieve the above objectives, the present invention employs the following industrial apparatus: The tubular chain conveyor A is connected to the top port of the pulping kettle, and the methanol mother liquor pump is connected to the top port of the pulping kettle through a basket filter; the bottom port of the pulping kettle is connected to the inlet of the horizontal scraper centrifuge, the outlet of the horizontal scraper centrifuge is connected to the top port of the mother liquor tank, the solid outlet of the horizontal scraper centrifuge is located above the tubular chain conveyor B, and the bottom port of the mother liquor tank is connected to the methanol mother liquor pump B; the tubular chain conveyor B is connected to the top port of the disc dryer, the lower outlet of the disc dryer is located above the tubular chain conveyor C, and the tubular chain conveyor C is connected to the ton bag packaging machine.

[0018] The beneficial effects of this invention are: (1) The quality of ammonium chloride, a byproduct of glycine, can be improved from qualified agricultural grade to superior grade, thereby increasing the value of the byproduct and ultimately reducing the production cost of glycine.

[0019] (2) This method improves the quality of ammonium chloride and also recovers some organic matter intermittently, which can improve the organic matter recovery rate.

[0020] (3) The methanol mother liquor generated by the aminoacetic acid itself is used without changing or affecting the normal operation of the aminoacetic acid, and without adding a methanol recovery process.

[0021] (4) This purification method only increases a small amount of equipment and production cost of RMB 20 / ton, but can increase the selling price by RMB 150 / ton. 10,000 tons of aminoacetic acid will produce about 10,000 tons of ammonium chloride as a byproduct, which can save RMB 1.3 million in production costs per year, resulting in significant economic benefits.

[0022] Red ammonium chloride is the main raw material in this case. First, aminated multi-walled carbon nanotubes are used to remove the high molecular weight organic matter (decolorization) from the glycine centrifugation filtrate that cannot be removed by methanol extraction. Then, the organic matter in the red ammonium chloride is extracted using the glycine centrifugation mother liquor. Using the principle of solubility saturation crystallization, the ammonium chloride in the red ammonium chloride squeezes out the ammonium chloride in the glycine centrifugation mother liquor, thus obtaining high-quality ammonium chloride.

[0023] After adopting this method, firstly, the quality of ammonium chloride, a byproduct of glycine, can be improved from qualified agricultural grade to superior grade, thereby increasing the value of the byproduct and ultimately reducing the production cost of glycine; secondly, while improving the quality of ammonium chloride, this method also intermittently recovers some organic matter, which can improve the organic matter recovery rate; and thirdly, it utilizes the methanol mother liquor generated by glycine itself, without changing or affecting the normal operation of glycine production, and without adding a methanol recovery process. Attached Figure Description

[0024] Figure 1 The diagram shows the structure of the device of the present invention. Among them, (1) tubular chain conveyor A; (2) methanol mother liquor pump A; (3) basket filter; (4) pulping kettle; (5) horizontal scraper centrifuge; (6) methanol filtrate tank; (7) methanol mother liquor pump B; (8) tubular chain conveyor B; (9) disc dryer; (10) tubular chain conveyor C; (11) ton bag packaging machine. Detailed Implementation

[0025] The embodiments of the present invention are used to further illustrate the substantive content of the invention, but are not intended to limit the invention: In this embodiment, the methanol mother liquor after separating glycine contains (wt%): 60-63.5% methanol, 8-10% ammonium chloride, 15-18% water, 1-2% hexamethylenetetramine, 1-2% ammonium dichloroacetate, 1-2% iminodiacetic acid, 1-2% ammonium acetate, and 60-70% whiteness.

[0026] Outer diameter 8-15nm, length ≤20μm, specific surface area >233m² 2 / g, bulk density 0.256g / cm³ 3 Electrical conductivity > 150 S / cm, suspension pH > 7. The amount of amination-modified carbon nanotubes added is 0.01-1 wt% of the methanol mother liquor.

[0027] Example 1 First, add 5500 kg of methanol mother liquor after separating glycine into a K10000L decolorization kettle, start stirring, add 3 g of activated carbon for decolorization (mass ratio 0.005), decolorize for 15 min, decolorize at 25℃, filter out the activated carbon, and then analyze the whiteness value of the methanol filtrate.

[0028] Example 2 First, add 5500 kg of methanol mother liquor after separating glycine into a K10000L decolorization kettle, start stirring, add 12 g of activated carbon for decolorization (mass ratio 0.022), decolorize for 15 min, decolorize at 25℃, filter out the activated carbon, and then analyze the whiteness value of the methanol filtrate.

[0029] Example 3 First, add 5500 kg of methanol mother liquor after separating glycine into a K10000L decolorization kettle, start stirring, add 18 g of activated carbon for decolorization (mass ratio 0.033), decolorize for 15 min, decolorize at 25℃, filter out the activated carbon, and then analyze the whiteness value of the methanol filtrate.

[0030] Example 4 First, add 5500 kg of methanol mother liquor after separating glycine into a K10000L decolorization kettle, start stirring, add 12 g of activated carbon for decolorization (mass ratio 0.022), decolorize for 30 min, decolorize at 25℃, filter out the activated carbon, and then analyze the whiteness value of the methanol filtrate.

[0031] Example 5 First, add 5500 kg of methanol mother liquor after separating glycine into a K10000L decolorization kettle, start stirring, add 12 g of activated carbon for decolorization (mass ratio 0.022), decolorize for 45 min, decolorize at 25℃, filter out the activated carbon, and then analyze the whiteness value of the methanol filtrate.

[0032] Example 6 First, add 5500 kg of methanol mother liquor after separating glycine into a K10000L decolorization kettle, start stirring, add 12 g of activated carbon for decolorization (mass ratio 0.022), decolorize for 15 min, decolorize at 30℃, filter out the activated carbon, and then analyze the whiteness value of the methanol filtrate.

[0033] Example 7 First, add 5500 kg of methanol mother liquor after separating glycine into a K10000L decolorization kettle, start stirring, add 12 g of activated carbon for decolorization (mass ratio 0.022), decolorize for 15 min, decolorize at 35℃, filter out the activated carbon, and then analyze the whiteness value of the methanol filtrate.

[0034] Example 8 First, add 5500 kg of methanol mother liquor after separating glycine into a K10000L decolorization kettle, start stirring, add 12 g of activated carbon for decolorization (mass ratio 0.022), decolorize for 15 min, decolorize at 40℃, filter out the activated carbon, and then analyze the whiteness value of the methanol filtrate.

[0035] Example 9 First, add 5500 kg of methanol mother liquor after separating glycine to a K10000L decolorization kettle, start stirring, add 5 g of aminated multi-walled carbon nanotubes for decolorization, with a mass ratio of 0.022, decolorization time of 45 min, decolorization temperature of 25℃, filter out the aminated multi-walled carbon nanotubes, and analyze the whiteness value of the methanol filtrate.

[0036] Examples 1-9, data comparison is shown in Table 1 below:

[0037] Aminated multi-walled carbon nanotubes (MWCNTs) were used to decolorize methanol mother liquor. The decolorization effect was mainly affected by the weight ratio (activated carbon nanotubes / methanol mother liquor), decolorization time, and decolorization temperature. The weight ratio (activated carbon / methanol mother liquor) had a greater impact, while the decolorization time and temperature had a smaller impact. When the ratio of aminated MWCNTs to methanol mother liquor was 0.022, the decolorization time was 15 min, and the decolorization temperature was 35℃, the whiteness of the mother liquor could exceed 90%.

[0038] Example 10 First, add 5500 kg of the decolorizing methanol mother liquor from Example 9 to a K10000L decolorizing reactor, start stirring, then add 650 kg of red ammonium chloride and 5 g of aminated multi-walled carbon nanotubes. The weight ratio (ammonium chloride / decolorizing mother liquor) is 0.12. The extraction time is 20 min, and the extraction temperature is 25℃. Organic matter is extracted from the red ammonium chloride from the decolorizing methanol mother liquor. After thorough mixing, the wet ammonium chloride is separated using a horizontal scraper centrifuge. The filtrate is returned to the methanol mother liquor. The centrifuge speed is 1000 rpm. The separated wet ammonium chloride is dried under a vacuum of -0.095 MPa at 80℃ for 1 h. The dried ammonium chloride is then analyzed for nitrogen and moisture content.

[0039] Example 11 First, add 5500 kg of the decolorizing methanol mother liquor from Example 7 to a K10000L decolorizing reactor, start stirring, add 450 kg of red ammonium chloride and 5 g of aminated multi-walled carbon nanotubes, with a weight ratio (ammonium chloride / decolorizing mother liquor) of 0.08, extraction time of 30 min, extraction temperature of 25℃, and extract organic matter from the red ammonium chloride from the decolorizing methanol mother liquor. After thorough mixing, separate the wet ammonium chloride product using a horizontal scraper centrifuge. Return the separated filtrate to the methanol mother liquor, centrifuge speed of 1000 rpm, and dry the separated wet ammonium chloride product under a drying vacuum of -0.095 MPa, drying temperature of 80℃, and drying time of 1 h. Analyze the nitrogen and moisture content of the dried ammonium chloride.

[0040] Example 12 First, add 5500 kg of the decolorizing methanol mother liquor from Example 7 to a K10000L decolorizing reactor, start stirring, add 450 kg of red ammonium chloride and 5 g of aminated multi-walled carbon nanotubes, with a weight ratio (ammonium chloride / decolorizing mother liquor) of 0.08, extraction time 20 min, extraction temperature 25℃. Organic matter is extracted from the red ammonium chloride from the decolorizing methanol mother liquor. After thorough mixing, separate the wet ammonium chloride product using a horizontal scraper centrifuge. Return the separated filtrate to the methanol mother liquor. The centrifuge speed is 1000 rpm. The separated wet ammonium chloride product is dried under a vacuum of -0.095 MPa, at a temperature of 95℃, for 1 h. The dried ammonium chloride is then analyzed for nitrogen and moisture content.

[0041] Example 13 First, add 5500 kg of the decolorizing methanol mother liquor from Example 7 to a K10000L decolorizing reactor, start stirring, and then add 450 kg of red ammonium chloride. The weight ratio (ammonium chloride / decolorizing mother liquor) is 0.08. The extraction time is 20 min, and the extraction temperature is 25℃. Organic matter is extracted from the red ammonium chloride from the decolorizing methanol mother liquor. After thorough mixing, the wet ammonium chloride is separated using a horizontal scraper centrifuge. The filtrate is returned to the methanol mother liquor. The centrifuge speed is 1000 rpm. The separated wet ammonium chloride is dried under vacuum at 95℃ for 1 h. The nitrogen and moisture content of the dried ammonium chloride is analyzed.

[0042] Example 14 First, add 5500 kg of the decolorizing methanol mother liquor from Example 7 to a K10000L decolorizing reactor, start stirring, and then add 450 kg of white ammonium chloride. The weight ratio (ammonium chloride / decolorizing mother liquor) is 0.08. The extraction time is 20 min, and the extraction temperature is 25℃. Organic matter is extracted from the red ammonium chloride by the decolorizing methanol mother liquor. After thorough mixing, the wet ammonium chloride is separated by a horizontal scraper centrifuge. The filtrate is returned to the methanol mother liquor. The centrifuge speed is 1000 rpm. The separated wet ammonium chloride is dried under vacuum at 95℃ for 1 h. The nitrogen and moisture content of the dried ammonium chloride is analyzed.

[0043]

[0044] Red ammonium chloride was purified using decolorized methanol mother liquor. The purification effect was mainly affected by factors such as the weight ratio (ammonium chloride / decolorized methanol mother liquor), the presence or absence of amination-modified multi-walled carbon nanotubes, extraction time, extraction temperature, centrifuge speed, drying vacuum degree, drying temperature, and drying time. The weight ratio (ammonium chloride / decolorized methanol mother liquor, amination-modified multi-walled carbon nanotubes / decolorized methanol mother liquor) had a greater impact, while the others had a smaller impact. When the weight ratio (ammonium chloride / decolorized methanol mother liquor) = 0.08~0.12, the extraction time was 20-30 min, the extraction temperature was 25-35℃, the drying temperature was 80-90℃, and the drying time was 1-2 h, high-quality ammonium chloride with a nitrogen content of not less than 25.4% and a moisture content of less than 0.5% could be obtained. The data for the decolorized methanol mother liquor and clean ammonium chloride, without the addition of amination-modified multi-walled carbon nanotubes, remained almost unchanged.

Claims

1. A process for purifying ammonium chloride, a byproduct of glycine production, in industrial-grade aminoacetic acid, characterized in that: The main steps include: (1) First, the methanol mother liquor after separating glycine is decolorized by activated carbon and / or aminated multi-walled carbon nanotubes; (2) Then, the by-product red ammonium chloride and aminated multi-walled carbon nanotubes are continuously added to the pulping kettle in a certain proportion and thoroughly mixed. (3) The slurry is continuously collected and fed into a horizontal scraper centrifuge to separate the wet ammonium chloride. The filtrate is then returned to the mother liquor pool. (4) The filtrate normally enters the methanol recovery and red ammonium chloride recovery process. The wet ammonium chloride enters the disc dryer for micro-negative pressure drying, which can produce agricultural-grade high-quality ammonium chloride.

2. The purification process for ammonium chloride, a byproduct of glycine, according to claim 1, is characterized in that, The activated carbon in step (1) has the following properties: 50~400 mesh, iodine adsorption value of 900~1500mg / g, pH=7~10, caramel decolorization of 80~130%, and moisture content of 1~3%.

3. The purification process for ammonium chloride, a byproduct of glycine, according to claim 1, is characterized in that, In step (1), the ratio of activated carbon to methanol mother liquor (mass ratio) is 0.001 to 0.005:

1.

4. The purification process for ammonium chloride, a byproduct of glycine, according to claim 1, is characterized in that, Properties of amination-modified carbon nanotubes in step (1) or (2): outer diameter 8-15 nm, length ≤20 μm, specific surface area >233 m² 2 / g, bulk density 0.256g / cm³ 3 Electrical conductivity > 150 S / cm, suspension pH > 7.

5. The purification process for ammonium chloride, a byproduct of glycine, according to claim 1, is characterized in that, In step (1) or (2), the amount of aminated multi-walled carbon nanotubes added is 0.01-1wt% of the amount of methanol mother liquor, the decolorization temperature is 25-45℃, and the decolorization time is 10-50min.

6. The purification process for ammonium chloride, a byproduct of glycine, according to claim 1, is characterized in that, The methanol mother liquor after separating glycine contains: 60-63.5 wt% methanol, 8-10 wt% ammonium chloride, 15-18 wt% water, 1-2 wt% hexamethylenetetramine, 1-2 wt% ammonium dichloroacetate, 1-2 wt% iminodiacetic acid, and 1-2 wt% ammonium acetate.

7. The purification process for ammonium chloride, a byproduct of glycine, according to claim 1, is characterized in that, Red ammonium chloride contains: nitrogen content 23~24.5 wt%, moisture 3~5 wt%, organic matter 6~8 wt%, and whiteness 50~60 wt%.

8. The purification process for ammonium chloride, a byproduct of glycine, according to claim 1, is characterized in that, The tray dryer has a drying temperature of 80~90℃, a vacuum degree of -0.05Mpa~-0.01Mpa, a stirring speed of 10~60rpm, a drying time of 10-30min, 15~22 drying trays, and 1-10 cooling trays.

9. The purification process for ammonium chloride, a byproduct of glycine, according to claim 1, is characterized in that, Pure ammonium chloride has an inorganic nitrogen content of 25.4-26%, a moisture content of 0.3-0.5%, and a whiteness of 90-95%.

10. The purification process for ammonium chloride, a byproduct of glycine, according to any one of claims 1-9, is characterized in that, The industrial-grade ammonium chloride purification unit used in this process consists of the following equipment: a tubular chain conveyor A is connected to the top port of the pulping kettle; a methanol mother liquor pump is connected to the top port of the pulping kettle through a basket filter; the bottom port of the pulping kettle is connected to the inlet of a horizontal scraper centrifuge; the outlet of the horizontal scraper centrifuge is connected to the top port of the mother liquor tank; the solid outlet of the horizontal scraper centrifuge is located above the tubular chain conveyor B; the bottom port of the mother liquor tank is connected to the methanol mother liquor pump B; the tubular chain conveyor B is connected to the top port of a disc dryer; the lower outlet of the disc dryer is located above the tubular chain conveyor C; and the tubular chain conveyor C is connected to a ton bag packaging machine.

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