CN109734637B - Methionine crystallization mother liquor treatment method - Google Patents
Methionine crystallization mother liquor treatment method Download PDFInfo
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- CN109734637B CN109734637B CN201910113860.9A CN201910113860A CN109734637B CN 109734637 B CN109734637 B CN 109734637B CN 201910113860 A CN201910113860 A CN 201910113860A CN 109734637 B CN109734637 B CN 109734637B
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Abstract
The invention relates to a methionine crystallization mother liquor treatment method, which takes methionine crystallization mother liquor extracted in the production process of a methionine sylvite process as a raw material and comprises the following steps: (1) heating and concentrating the extracted methionine crystallization mother liquor to obtain mixed liquor of potassium methionine and potassium carbonate, then introducing carbon dioxide gas to respectively obtain a potassium bicarbonate solid containing methionine and a potassium bicarbonate filtrate, and returning the solid to the hydrolysis of 5- (2-methylthioethyl) -hydantoin; (2) and (2) performing bipolar membrane electrodialysis treatment on the potassium bicarbonate filtrate obtained in the step (1), obtaining an aqueous solution containing organic matters in an acid chamber, concentrating and burning the aqueous solution, obtaining a dilute potassium hydroxide aqueous solution in an alkali chamber, and returning the dilute potassium hydroxide aqueous solution to the hydrolysis of the 5- (2-methylthioethyl) -hydantoin. The method uses carbon dioxide acidification and bipolar membrane electrodialysis again to fully recover methionine and potassium ions in the mother liquor, avoids loss of valuable compounds in the mother liquor and reduces production cost.
Description
Technical Field
The invention belongs to the field of chemical industry, and particularly relates to a method for treating methionine crystallization mother liquor collected in a methionine potassium salt production process.
Background
The main known production method of methionine is to hydrolyze 5- (2-methylthioethyl) -hydantoin aqueous solution in the presence of potassium carbonate to obtain potassium methionine aqueous solution containing potassium carbonate, then introduce carbon dioxide into the potassium methionine aqueous solution containing potassium carbonate to neutralize, crystallize and separate methionine, and respectively obtain wet methionine and potassium bicarbonate aqueous solution (filtrate) containing methionine; the methionine-containing potassium bicarbonate aqueous solution (filtrate) is concentrated and returned to the hydrolysis process of the 5- (2-methylthioethyl) -hydantoin aqueous solution.
In the prior technical scheme, the main impurities in the mother liquor are methionine dimer, the methionine dimer can be converted into methionine under alkaline condition, the methionine dimer can be regarded as an equivalent of methionine, only if the methionine dimer in the mother liquor is accumulated too much, the crystallization of the methionine is influenced, however, other substances added in the crystallization process of the methionine, such as polyvinyl alcohol, sorbitan laurate, hydroxypropyl methyl cellulose, and the like can be accumulated along with the circulation of the mother liquor, no matter the method adds an organic solvent which is miscible with water to precipitate the methionine and the potassium bicarbonate, the obtained methionine and the potassium bicarbonate can carry the impurities, and the impurities can be brought into a system, in fact, the method fundamentally solves the problem of accumulation of the impurities in the mother liquor, and the fundamentally effective method is to partially extract the mother liquor for incineration treatment, thereby avoiding or addressing the accumulation of impurities in the system. Of course, such treatment is carried out at the expense of the environment and the economy, because the mother liquor of incineration treatment also contains methionine and potassium bicarbonate with considerable value, and the mother liquor of incineration is rich in potassium ions.
Adding water-miscible organic solvents such as methanol, acetone and isopropanol into the mother liquor, and precipitating a large amount of methionine and potassium bicarbonate, wherein after the methionine and the potassium bicarbonate are taken, the mother liquor not only contains methanol or acetone and isopropanol, but also contains other impurities such as methionine dimer, potassium formate, potassium propionate, potassium acetate, potassium butyrate, potassium carbonate, polyvinyl alcohol, sorbitan laurate, hydroxypropyl methylcellulose and the like. Such mother liquor treatment is difficult because a large amount of organic solvent is used first, and therefore the solvent is required to be recovered, the organic solvent is recovered by distillation and rectification, and the residue after the recovery of the organic solvent must be incinerated so that the impurities thereof are not returned to the methionine production system. The recovery of the solvent requires a large amount of energy consumption and a large amount of equipment investment, and the loss of the solvent is inevitable, increasing the production cost of methionine.
Aiming at the defects, through the production practice of the inventor for many years, a methionine crystallization mother liquor egg production treatment method is developed, the method fully utilizes methionine and potassium bicarbonate in the produced methionine crystallization mother liquor to recover methionine, potassium bicarbonate and potassium hydroxide, plays a role in comprehensively utilizing wastes, achieves the win-win purpose of economy and environment, avoids the loss of methionine and potassium ions through incineration treatment, avoids the traditional use of organic solvents, and avoids the pollution to the environment.
Disclosure of Invention
In order to solve these problems, the present inventors have found an effective method for recovering methionine, potassium bicarbonate and potassium hydroxide from the discharged mother liquor, which avoids the accumulation of organic impurities in the mother liquor. As a result, the method can fully utilize methionine, potassium bicarbonate and potassium hydroxide in the discharged mother liquor, and achieve the win-win effect on economy and environmental protection. Carrying out heat treatment and concentration on the discharged mother liquor to decompose potassium bicarbonate into potassium carbonate, then introducing carbon dioxide for acidification to simultaneously separate out methionine and potassium bicarbonate to obtain a solid potassium bicarbonate containing methionine, circulating the solid to the step of hydrolyzing 5- (2-methylthioethyl) -hydantoin, heating and decomposing the filtrate, carrying out electrodialysis treatment on the filtrate by using a bipolar membrane to control the pH value and the potassium ion concentration of the material in an acid chamber, obtaining an organic matter aqueous solution in the acid chamber, and then carrying out incineration treatment; the alkali chamber obtains a dilute potassium hydroxide aqueous solution which is directly or circularly recycled to the 5- (2-methylmercapto ethyl) -hydantoin hydrolysis step after being concentrated. The present invention has been accomplished based on the above findings, which are based on a comprehensive consideration of wastes and a large number of experimental demonstrations and market value of by-products thereof.
According to the methionine crystallization mother liquor treatment method provided by the invention, methionine crystallization mother liquor extracted in the production process of a methionine potassium salt process is taken as a raw material, and the method comprises the following steps:
(1) heating and concentrating the extracted methionine crystallization mother liquor to obtain mixed liquor of potassium methionine and potassium carbonate, then introducing carbon dioxide gas to respectively obtain a potassium bicarbonate solid containing methionine and a potassium bicarbonate filtrate, and returning the solid to the hydrolysis process of 5- (2-methylthioethyl) -hydantoin (see background technology);
(2) performing bipolar membrane electrodialysis treatment on the potassium bicarbonate filtrate obtained in the step (1), obtaining an aqueous solution (waste) containing organic matters in an acid chamber, and concentrating and burning the aqueous solution; the alkali chamber obtains dilute potassium hydroxide aqueous solution (recycling), and the dilute potassium hydroxide aqueous solution is returned to the hydrolysis process of the 5- (2-methylthioethyl) -hydantoin (see background technology).
Further, the methionine crystallization mother liquor is as follows: in the potassium salt process, carbon dioxide is introduced for neutralization, and crystallization mother liquor is obtained after methionine is separated and consists of 4.0-9.0 wt% of methionine, 4.0-11.0 wt% of potassium ions, 0.01-1.0 wt% of methionine dipeptide, 0.01-0.5 wt% of other organic impurities and 7.5-9.0 of the pH value of the mother liquor. In this case, if the entire amount of the mother liquor is recycled, impurities accumulate in the step of re-hydrolyzing 5- (2-methylthioethyl) -hydantoin, and therefore the mother liquor needs to be discharged at a prescribed rate. Further, the treatment of discharging the mother liquor as a waste liquid is not a good measure, thus resulting in the loss of methionine and potassium hydrogencarbonate contained therein, and the load and consumption of waste liquid treatment are very high.
Further, the methionine crystallization mother liquor in the step (1) is concentrated until the concentration of potassium ions is 20.0wt% -30 wt%, the concentration temperature is 80-140 ℃, and the pH value of the aqueous solution is 12-14. The concentration is to precipitate the methionine and the potassium bicarbonate as much as possible, and reduce the residue of the methionine and the potassium bicarbonate in the mother liquor.
Further, in the step (1), carbon dioxide is neutralized, the pressure of the introduced carbon dioxide is 0.1-1.0 Mpa, the neutralization temperature is 0-10 ℃, the obtained solid is potassium bicarbonate solid containing a small amount of methionine, the solid is returned to the 5- (2-methylthioethyl) -hydantoin by hydrolysis, and the concentration of potassium ions in the filtrate is 6.0-9.0 wt%. The solid matter is mainly potassium bicarbonate, which accounts for 40-65 wt% of the solid matter, and methionine accounts for 10-30 wt%.
Further, the filtrate is a potassium bicarbonate aqueous solution, and contains a small amount of one or more of methionine, methionine dimer, potassium formate, potassium propionate, potassium acetate, potassium butyrate, potassium carbonate, potassium citrate, polyvinyl alcohol, sorbitan laurate, hydroxypropyl methylcellulose and the like. Some impurities in the mother liquor are generated by reaction, such as methionine dimer, potassium formate and the like, the potassium formate is generated by hydrolysis due to the excess of hydrocyanic acid serving as a raw material, and the proportion of propionaldehyde in the impurities is large; the added impurities include propionic acid, acetic acid, butyric acid, citric acid, polyvinyl alcohol, sorbitan laurate, hydroxypropyl methylcellulose, etc., and the impurities include a catalyst added during the production of cyanohydrin, and impurities inevitably exist when methionine is crystallized to obtain a high bulk density.
Further, in the bipolar membrane electrodialysis in the step (2), an acid chamber obtains an organic compound aqueous solution, wherein the pH value is 6-7, the potassium ion concentration is lower than 0.10wt%, a potassium hydroxide aqueous solution is obtained in an alkali chamber, the potassium hydroxide concentration is 2.0-10.0 wt%, and the bipolar membrane electrodialysis working temperature is 20-35 ℃.
Further, the material entering the bipolar membrane electrodialysis treatment is preferably subjected to pretreatment, that is: heating to decompose potassium bicarbonate into potassium carbonate, cooling, passing through a precision filter, and treating with a bipolar membrane electrodialyzer.
Further, the operation of the material pretreatment and the bipolar membrane electrodialysis may be performed in one or more cycles until the potassium ion concentration in the acid compartment of the bipolar membrane electrodialysis is reduced to within 0.10 wt%. Methionine and other organic substances such as methionine dimer, potassium formate, potassium propionate, potassium acetate, potassium butyrate, potassium carbonate, polyvinyl alcohol, sorbitan laurate, hydroxypropyl methylcellulose, etc. remain in the acid compartment, and the aqueous solution of potassium hydroxide formed in the base compartment for the migrating potassium ions is substantially free or very low in impurity content, except for potassium hydroxide. Therefore, the bipolar membrane electrodialysis device is utilized to not only separate potassium ions from the mother liquor of methionine and other organic impurities, but also achieve the purpose of recovering valuable potassium ions.
Further, the potassium hydroxide in the base compartment is returned to the process of hydrolyzing 5- (2-methylthioethyl) -hydantoin either directly or after concentration.
The invention has the advantages and positive effects that: the method provided by the invention fully utilizes methionine and potassium bicarbonate in the extracted methionine crystallization mother liquor to recover methionine, potassium bicarbonate and potassium hydroxide, plays a role in comprehensive utilization of waste, achieves economic and environmental win-win effects, avoids loss of methionine and potassium ions through incineration treatment, avoids traditional use of organic solvents, avoids environmental pollution, achieves economic and environmental win-win effects, is low in production cost, simple in production and easy to operate, and has a very high industrial application value.
Detailed Description
The present invention is further illustrated by the following specific examples, which are intended to be illustrative, not limiting and are not intended to limit the scope of the invention.
Examples
Adding 500 kg of methionine crystallization mother liquor into a reaction kettle, wherein the mass percent of methionine is 7.5wt%, the mass percent of methionine dimer is 0.5wt%, the mass percent of potassium ions is 9.5wt%, the mass percent of other organic matters is 0.02wt%, and the pH of the mother liquor is 8.7; the mother liquor is heated to 120 ℃, and then concentrated to the concentration of 28.5wt% of potassium ions, the concentration of 22.5wt% of methionine, the concentration of methionine dimer is 1.5wt%, the total concentration of other organic matters is 0.06wt%, and the pH value of the feed liquor is 12.8 (the amount of the mother liquor extracted is 1-2% of the total circulating amount).
Cooling the obtained mixed solution of the potassium methionine and the potassium carbonate to 5 ℃, then introducing carbon dioxide, introducing the carbon dioxide under the pressure of 0.5Mpa, neutralizing the pH value of 8.2, separating out a large amount of milky white precipitate, and performing suction filtration to obtain 142.0 kilograms of solid potassium bicarbonate containing methionine, wherein the content of the potassium bicarbonate is 65.0wt%, the content of the methionine is 24.65wt%, and the solid is returned to the process of hydrolyzing the 5- (2-methylthioethyl) -hydantoin in the production process of the methionine. The filtrate obtained amounted to 147.45 kg, with a potassium bicarbonate content of 20.0 wt.%, a methionine content of 1.7 wt.% and other organic impurities content of 1.8 wt.%.
And heating the obtained filtrate to completely decompose potassium bicarbonate into potassium carbonate, cooling to 25 ℃, passing through a precision filter, and entering a bipolar membrane electrodialysis device for potassium removal, wherein potassium ions in an acid chamber in the bipolar membrane electrodialysis device are gradually reduced, the pH value is gradually reduced, the concentration of potassium ions in an alkali chamber is gradually increased, and the pH value is gradually increased. When the pH value in the acid chamber can not be reduced, heating and decomposing the material in the acid chamber to convert potassium bicarbonate into potassium carbonate again, performing bipolar membrane electrodialysis potassium removal operation, and repeating the above operation until the concentration of potassium ions in the acid chamber is reduced to below 0.1 wt%. The acid chamber obtains aqueous solution containing methionine (a small amount) and other organic matters, and the aqueous solution is directly incinerated after concentration treatment (because the methionine contained in the aqueous solution accounts for very little total methionine and accounts for 6.67 percent of the methionine in the mother solution, the methionine can be completely ignored), the alkaline chamber obtains 209.18 kilograms of potassium hydroxide with 7.5 weight percent, and the recovery rate of potassium ions reaches 95 percent. The potassium hydroxide aqueous solution can be directly returned to the 5- (2-methylmercapto ethyl) -hydantoin hydrolysis process in the methionine production process or after concentration treatment.
Claims (9)
1. A methionine crystallization mother liquor treatment method is characterized by comprising the following steps:
(1) taking methionine crystallization mother liquor extracted in the process of producing methionine sylvite as a raw material, heating and concentrating the methionine crystallization mother liquor to obtain mixed liquor of potassium methionine and potassium carbonate, then introducing carbon dioxide gas to respectively obtain a potassium bicarbonate solid containing methionine and a potassium bicarbonate filtrate, and returning the solid to the hydrolysis process of 5- (2-methylthioethyl) -hydantoin;
(2) performing bipolar membrane electrodialysis treatment on the potassium bicarbonate filtrate obtained in the step (1), obtaining an aqueous solution containing organic matters in an acid chamber, and performing concentration and incineration treatment; the alkali chamber obtains dilute potassium hydroxide aqueous solution which is returned to the 5- (2-methylmercapto ethyl) -hydantoin hydrolysis process.
2. The method for treating a methionine crystallization mother liquor according to claim 1, wherein the methionine crystallization mother liquor is: in the sylvite process, carbon dioxide is introduced for neutralization, and crystallization mother liquor is obtained after methionine is separated, wherein the mother liquor comprises methionine, potassium bicarbonate, potassium formate, potassium propionate, potassium citrate, potassium acetate, potassium butyrate, potassium carbonate, methionine dipeptide and other organic matters, namely polyvinyl alcohol, sorbitan laurate or hydroxypropyl methyl cellulose, wherein the methionine accounts for 4.0-9.0 wt%, the potassium ions account for 4.0-11.0 wt%, the methionine dipeptide accounts for 0.01-1.0 wt%, the other organic matter impurities account for 0.01-0.5 wt%, and the pH value of the mother liquor is 7.5-9.0.
3. The method for treating the methionine crystallization mother liquor according to claim 1, wherein the methionine crystallization mother liquor in the step (1) is concentrated to a potassium ion concentration of 20.0wt% to 30wt%, and the concentration temperature is 80 ℃ to 140 ℃.
4. The method for treating methionine crystallization mother liquor according to claim 1, wherein the carbon dioxide is neutralized in the step (1), the pressure of introducing the carbon dioxide is 0.1-1.0 Mpa, the neutralization temperature is 0-10 ℃, and the obtained solid is potassium bicarbonate solid containing a small amount of methionine.
5. The method for treating a methionine crystallization mother liquor according to claim 4, wherein the filtrate is a potassium bicarbonate aqueous solution containing one or more of methionine, methionine dimer, potassium formate, potassium propionate, potassium acetate, potassium butyrate, potassium carbonate, potassium citrate, polyvinyl alcohol, sorbitan laurate and hydroxypropyl methylcellulose.
6. The method for treating methionine crystallization mother liquor according to claim 1, wherein in the step (2) bipolar membrane electrodialysis, the acid chamber obtains an aqueous solution of organic compound with pH of 6-7 and potassium ion concentration of less than 0.10wt%, the alkali chamber obtains an aqueous solution of potassium hydroxide with potassium hydroxide concentration of 2.0-10.0 wt%, and the bipolar membrane electrodialysis working temperature is 20-35 ℃.
7. A methionine crystallization mother liquor treatment method according to claim 6, wherein the material entering into bipolar membrane electrodialysis treatment is pretreated by: heating to decompose potassium bicarbonate into potassium carbonate, cooling, passing through a precision filter, and treating with a bipolar membrane electrodialyzer.
8. The method for treating methionine crystallization mother liquor according to claim 7, wherein the operation of the material pretreatment and bipolar membrane electrodialysis is performed in one or more cycles until the potassium ion concentration in the acid compartment of the bipolar membrane electrodialysis is reduced to within 0.10 wt%.
9. The method for treating methionine crystallization mother liquor according to claim 6, wherein the potassium hydroxide in the alkaline chamber is returned to the process of hydrolyzing 5- (2-methylthioethyl) -hydantoin directly or after concentration.
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| CN112679397B (en) * | 2020-12-21 | 2023-08-01 | 宁夏紫光天化蛋氨酸有限责任公司 | Preparation method of DL-methionine |
| CN112679401B (en) * | 2020-12-30 | 2022-12-09 | 天宝动物营养科技股份有限公司 | Potassium carbonate full-circulation process for preparing D, L-methionine |
| CN114163367A (en) * | 2021-12-09 | 2022-03-11 | 宁夏紫光天化蛋氨酸有限责任公司 | Methionine environment-friendly preparation method based on carbon dioxide acidification method |
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| CN102399177B (en) * | 2010-09-15 | 2016-02-24 | 李宽义 | The environment-friendly clean process method of serialization synthetic methionine |
| CN103922980B (en) * | 2014-04-22 | 2016-08-24 | 中国科学技术大学 | A kind of method utilizing bipolar membrane electrodialysis to isolate methionine from the mixed solution of methionine salt and carbonate |
| CN104130169A (en) * | 2014-07-08 | 2014-11-05 | 重庆紫光化工股份有限公司 | Environment-friendly clean production method of D,L-methionine |
| CN105671587B (en) * | 2015-12-10 | 2018-02-13 | 浙江工业大学 | A kind of method and its device for preparing methionine and reclaiming accessory substance carbon dioxide |
| CN106083674B (en) * | 2016-06-03 | 2018-11-06 | 宁夏紫光天化蛋氨酸有限责任公司 | A kind of production method reducing carbonate in methionine saponification liquor |
| CN106432018A (en) * | 2016-09-14 | 2017-02-22 | 宁夏紫光天化蛋氨酸有限责任公司 | Method for environment-friendly clean production of D,L-methionine |
| CN106432020B (en) * | 2016-09-14 | 2018-11-20 | 宁夏紫光天化蛋氨酸有限责任公司 | A kind of D, the isolation and purification method of L-Methionine |
| CN108658821B (en) * | 2017-06-13 | 2020-07-17 | 宁夏紫光天化蛋氨酸有限责任公司 | Clean production method of D, L-methionine and product thereof |
| CN109232339B (en) * | 2018-11-09 | 2020-09-08 | 天宝动物营养科技股份有限公司 | Cleaning process for co-production of D, L-methionine, D, L-methionine hydroxy analogue and calcium salt thereof |
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