Treatment method for oxadiargyl byproduct etherified salt slag and hydrolysis waste sulfuric acid

Abstract

The invention discloses a treatment method of oxadiargyl byproduct etherified salt slag and hydrolysis waste sulfuric acid, which comprises the following steps: comprehensively treating the byproduct etherified salt slag and hydrolysis waste sulfuric acid generated in the production process of oxadiargyl; the method comprises the following steps: converting etherified salt slag and potassium hydrogen sulfate into an isopropyl bromide product capable of being used for producing oxadiargyl and a potassium hydrogen sulfate product capable of being directly sold, dropwise adding hydrolyzed waste sulfuric acid into a mixed solution of etherified salt slag, water and isopropanol, carrying out a reflux reaction, carrying out atmospheric distillation, cooling and filtering to obtain an isopropyl bromide crude product and a potassium hydrogen sulfate crude product; the treatment method is simple and convenient to operate, the treatment difficulty of the etherified salt slag and the hydrolysis waste sulfuric acid can be solved at the same time, the treatment cost is reduced, effective recovery of the etherified salt slag and the hydrolysis waste sulfuric acid is realized, effective components in the two wastes are fully utilized, and the method is suitable for industrial production. The treatment process basically has no secondary pollution, has no special requirements on production equipment, and can be suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of by-products in chemical production, and particularly relates to a method for treating by-product etherification salt residue and hydrolyzed waste sulfuric acid of propyzamide. Background Art

[0002] Propyzamide is a herbicide that can be widely applied to crop fields such as rice, vegetables, and orchards. It mainly acts by contact absorption through the young buds or seedlings of sensitive weeds such as barnyard grass before and after the emergence of weeds. Propyzamide has little mobility in the soil. Using it for weed control can avoid excessive pesticide residues in crops. The action mechanism of propyzamide is similar to that of oxadiazon, but compared with oxadiazon, propyzamide has advantages such as a wide control range, strong compatibility, and high activity.

[0003] The preparation methods of propyzamide can generally be divided into three types. Two of the methods both use 2,4-dichlorophenol as the starting material, and the third method is to use oxadiazon to obtain oxadiazonol through a hydrolysis reaction, and then use a C2-C5 fatty alcohol as a solvent, an inorganic base as an acid-binding agent, and under the action of a catalyst, an alkylation reaction is carried out to generate an alcohol solution of propyzamide, and then propyzamide is obtained through steps such as filtration, washing, cooling crystallization, and drying.

[0004] In the preparation process of propyzamide, 2,4-dichloro-5-isopropoxynitrobenzene is both an intermediate of oxadiazon and an important intermediate of propyzamide. Generally, 2,4-dichloro-5-isopropoxynitrobenzene is prepared by an etherification reaction of 2,4-dichloro-5-nitrophenol. The reaction equation is as follows: During this etherification reaction, a large amount of etherification salt residue will be generated. Such etherification salt residue has a complex composition and contains a variety of inorganic substances and a variety of organic components, belonging to production waste. Moreover, during the process of oxadiazon reacting with water under the catalysis of concentrated sulfuric acid to generate the intermediate oxadiazonol and isopropanol, a large amount of hydrolyzed waste sulfuric acid will be generated. The reaction equation is as follows: This hydrolyzed waste sulfuric acid also contains a variety of complex components and also belongs to production waste. At present, when treating the etherification salt residue and hydrolyzed waste sulfuric acid separately, there are problems such as great difficulty in treatment technology, high cost of required equipment configuration, which is not conducive to expanding to industrial production, resulting in a problem that the treatment cost is not proportional to the output. The unprocessed waste continues to accumulate, making the treatment of both etherification salt residue and hydrolyzed waste sulfuric acid difficult points in the enterprise's environmental protection governance. Summary of the Invention

[0005] The object of the present invention is to provide a method for treating the by-product etherification salt residue and hydrolyzed waste sulfuric acid of propyzamide, so as to solve the problem that when the etherification salt residue and hydrolyzed waste sulfuric acid are treated separately, the technical difficulty is large, resulting in a disproportionate treatment cost and output.

[0006] To solve the above technical problems, the present invention provides a method for treating the by-product etherification salt residue and hydrolyzed waste sulfuric acid of propyzamide, comprising the following steps: Mix the etherification salt residue, water and isopropanol and stir evenly to obtain a mixed solution dissolving the etherification salt residue and isopropanol; Drop the hydrolyzed waste sulfuric acid into the mixed solution dissolving the etherification salt residue and isopropanol, and obtain crude isopropyl bromide after reflux reaction and atmospheric distillation; The residual liquid after the atmospheric distillation is cooled and filtered to obtain crude potassium bisulfate; The crude isopropyl bromide is washed with water to obtain isopropyl bromide product, and the isopropyl bromide product can be used for the production of propyzamide; The crude potassium bisulfate is refined, purified and dried to obtain a potassium bisulfate product that can be directly sold.

[0007] It should be noted in the solution that the main components of the etherification salt residue are KBr, KHCO 3 , K 2 CO 3 , 2,4-dichloro-5-isopropoxynitrobenzene and water, and the mass contents of KBr, KHCO 3 , K 2 CO 3 , 2,4-dichloro-5-isopropoxynitrobenzene and water are 35-65%, 30-50%, 1-10%, 0.1-3% and 0.5-3% respectively.

[0008] Further, it is worth noting that the main components of the hydrolyzed waste sulfuric acid are sulfuric acid, isopropanol and water, and the mass contents of sulfuric acid, isopropanol and water are 50%-90%, 3%-30% and 10%-30% respectively.

[0009] As a preferred embodiment, the mass ratio of the dissolved etherification salt residue, the isopropanol and the hydrolyzed waste sulfuric acid is 1:0.2-0.6:1.5-3.

[0010] As a preferred embodiment, the dropping temperature of the hydrolyzed waste sulfuric acid is maintained below 20°C, and the dropping time is 1-3 hours.

[0011] As a preferred embodiment, the reflux reaction time is 2-4 hours.

[0012] As a preferred embodiment, the heating can be stopped when the temperature of the atmospheric distillation reaches 100°C.

[0013] As a preferred embodiment, a method for treating by-product etherification salt residue and hydrolyzed waste sulfuric acid of oxadiargyl further includes recycling the filtrate after cooling and filtration to the next batch of reactions, and substituting part of the hydrolyzed waste sulfuric acid by dripping it into the mixed solution of dissolved etherification salt residue and isopropanol.

[0014] As a preferred embodiment, a method for treating by-product etherification salt residue and hydrolyzed waste sulfuric acid of oxadiargyl further includes absorbing the reaction tail gas generated in the reflux reaction and the atmospheric distillation process with water to obtain hydrobromic acid, and using the hydrobromic acid to replace the filtrate after multiple cycles of recycling.

[0015] Furthermore, it is worth noting that the content of isopropyl bromide in the isopropyl bromide product is more than 98%; the content of potassium bisulfate in the potassium bisulfate product is more than 98%.

[0016] Compared with the prior art, a method for treating by-product etherification salt residue and hydrolyzed waste sulfuric acid of oxadiargyl provided by the present invention has at least the following beneficial effects: Mix the etherification salt residue, water and isopropanol evenly by stirring. While dissolving the etherification salt residue, since the hydrolyzed waste sulfuric acid contains isopropanol, but the content is lower than the required amount for the subsequent reaction, a certain amount of isopropanol needs to be supplemented in advance. Then, drip the hydrolyzed waste sulfuric acid into the mixed solution of dissolved etherification salt residue and isopropanol. After reflux reaction and atmospheric distillation, a crude product of isopropyl bromide is obtained. The solid filter residue after cooling and filtration of the residual liquid after atmospheric distillation is the crude product of potassium bisulfate. The crude product of isopropyl bromide can be obtained as an isopropyl bromide product that can be used in the production of oxadiargyl after washing with water. The crude product of potassium bisulfate can be obtained as a salable potassium bisulfate product after refining, purification and drying. This treatment method is simple to operate, basically has no secondary pollution during the treatment process, and has no special requirements for production equipment. The entire treatment process can be realized by using basic general equipment, and it can be applied to industrial production.

[0017] By comprehensively treating the by-product etherification salt residue and hydrolyzed waste sulfuric acid generated in the production process of oxadiargyl by this method, the two are converted into an isopropyl bromide product that can be used in the production of oxadiargyl and a potassium bisulfate product that can be directly sold. While reducing the treatment cost of the etherification salt residue and hydrolyzed waste sulfuric acid, the effective recovery of the two is realized, the effective components in the two wastes are fully utilized, and at the same time, the difficulties in treating the etherification salt residue and hydrolyzed waste sulfuric acid are solved, and the economic and environmental benefits created by the recovery are remarkable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0019] Figure 1 A process flow diagram for the treatment method of the by - product etherification salt residue and hydrolyzed waste sulfuric acid provided by the present invention; Figure 2 A gas chromatogram of the isopropyl bromide product obtained by the treatment method of the by - product etherification salt residue and hydrolyzed waste sulfuric acid provided by the present invention. Detailed implementation manners

[0020] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0021] The core of the present invention is to provide a treatment method for the by - product etherification salt residue and hydrolyzed waste sulfuric acid of propyzamide, which solves the problem that when separately treating the etherification salt residue and hydrolyzed waste sulfuric acid, the technical difficulty is so great that the treatment cost is disproportionate to the output.

[0022] Figure 1 A process flow diagram for the treatment method of the by - product etherification salt residue and hydrolyzed waste sulfuric acid provided by the present invention, Figure 2 A gas chromatogram of the isopropyl bromide product obtained by the treatment method of the by - product etherification salt residue and hydrolyzed waste sulfuric acid provided by the present invention, see Figures 1 to 2 .

[0023] A treatment method for the by - product etherification salt residue and hydrolyzed waste sulfuric acid of propyzamide includes the following steps: Mix the etherification salt residue, water and isopropyl alcohol evenly by stirring to obtain a mixed solution dissolving the etherification salt residue and isopropyl alcohol; It should be noted that the main components of the etherification salt residue are KBr, KHCO 3 , K 2 CO 3 , 2,4 - dichloro - 5 - isopropoxynitrobenzene and moisture. The mass contents of KBr, KHCO 3 , K 2 CO 3 , 2,4 - dichloro - 5 - isopropoxynitrobenzene and moisture are 35 - 65%, 30 - 50%, 1 - 10%, 0.1 - 3% and 0.5 - 3% respectively.

[0024] The etherification salt residue is dissolved in water and mixed with supplementary isopropanol to form a mixed solution dissolving the etherification salt residue and isopropanol. Hydrolyzed waste sulfuric acid is dropped into the mixed solution of the dissolved etherification salt residue and isopropanol. Further, it should be noted that the main components of the hydrolyzed waste sulfuric acid are sulfuric acid, isopropanol and water, and the mass contents of sulfuric acid, isopropanol and water are 50% - 90%, 3 - 30% and 10 - 30% respectively. The role of supplementary isopropanol is that although the hydrolyzed waste sulfuric acid contains a certain amount of isopropanol, the content of isopropanol in the hydrolyzed waste sulfuric acid is still lower than the amount of isopropanol required for the subsequent reaction. Therefore, it is necessary to supplement and add isopropanol in advance to ensure the complete reaction. As a preferred embodiment, the dropping temperature of the hydrolyzed waste sulfuric acid is kept below 20°C, and the dropping time is 1 - 3 hours.

[0025] After the dropping of the hydrolyzed waste sulfuric acid is completed, the mixture of the dissolved etherification salt residue, isopropanol and hydrolyzed waste sulfuric acid is subjected to heating reflux reaction and atmospheric distillation to obtain crude isopropyl bromide. As a preferred embodiment, the mass ratio of the dissolved etherification salt residue, isopropanol and hydrolyzed waste sulfuric acid is 1:0.2 - 0.6:1.5 - 3. It should be noted that the reflux reaction time is 2 - 4 hours. After the reflux reaction is completed, a distillation device is installed on the reaction vessel, and the reaction device can be heated by a heating jacket. Further, it should be noted that during atmospheric distillation, the heating of the reaction device can be stopped when the temperature of the reaction device reaches 100°C. When applied to industrial production, production equipment that can meet the aforementioned reaction conditions can be used. Since the corresponding industrial production equipment does not belong to the protection scope of the present invention, it will not be elaborated here.

[0026] Potassium bromide contained in the etherification salt residue reacts with sulfuric acid in the hydrolyzed waste sulfuric acid to generate hydrogen bromide and potassium bisulfate. In this chemical reaction, sulfuric acid acts as both a reactant and a catalyst. Then, the generated hydrogen bromide will continue to react with the supplementary added isopropanol and isopropanol in the hydrolyzed waste sulfuric acid to generate isopropyl bromide and water. The chemical reaction equation is as follows: KBr + H 2 SO 4 HBr + KHSO 4 HBr + (CH 3 ) 2 CHOH ====== (CH 3 ) 2 CHBr+ H 2 O The reflux reaction can ensure that potassium bromide, sulfuric acid, isopropyl alcohol, and hydrogen bromide as reactants can participate in the reaction as fully as possible, prevent the loss of reactants during the process of maintaining boiling for a long time, and improve the conversion rate of etherification salt residue and hydrolyzed waste sulfuric acid into isopropyl bromide and potassium bisulfate; isopropyl bromide is separated by atmospheric distillation. During the atmospheric distillation process, the distillate contains components such as isopropyl bromide, a small amount of acidic water, and isopropyl alcohol. The collected distillate is stratified. After stratification, isopropyl bromide is located in the lower layer. It should be noted that the isopropyl bromide obtained at this time is a crude product of isopropyl bromide and cannot be directly used in the production of oxadiargyl.

[0027] Meanwhile, the main components of KHCO 3 , K 2 CO 3 in the etherification salt residue react with the sulfuric acid in the hydrolyzed waste sulfuric acid respectively, and the reaction products are all potassium bisulfate, water, and carbon dioxide. The chemical reaction equations are as follows: KHCO 3 + H 2 SO 4 ====== KHSO 4 + H 2 O + CO 2 K 2 CO 3 + 2H 2 SO 4 ====== 2KHSO 4 + H 2 O + CO 2 The residual liquid after atmospheric distillation is cooled and filtered to obtain crude potassium bisulfate; After separating the crude isopropyl bromide by atmospheric distillation, the main component of the residual solid-liquid mixture (residual liquid) is potassium bisulfate. The solid filter residue obtained by cooling and filtering is the crude potassium bisulfate.

[0028] The crude isopropyl bromide is washed with water to obtain isopropyl bromide product, and the isopropyl bromide product can be used in the production of oxadiargyl; By washing with water to remove impurities such as a small amount of acidic water and isopropyl alcohol in the crude isopropyl bromide, the isopropyl bromide product that can be used in the production of oxadiargyl can be obtained. It should be noted that the isopropyl bromide content in the isopropyl bromide product reaching more than 98% can be used in the production of oxadiargyl.

[0029] The crude potassium bisulfate is refined, purified, and dried to obtain a potassium bisulfate product that can be directly sold.

[0030] The content of potassium bisulfate in the crude potassium bisulfate can be increased through refining and purification. After drying, a potassium bisulfate product with a purity meeting the selling standard can be obtained. It should be noted that the content of potassium bisulfate in the potassium bisulfate product that can be directly sold as a by-product is more than 98%.

[0031] Through the above treatment steps, the by-product etherification salt residue and hydrolyzed waste sulfuric acid generated in the production process of oxadiargyl can be comprehensively treated, and the two are converted into isopropyl bromide products and potassium bisulfate products. The isopropyl bromide product can be used again in the production of oxadiargyl, and the potassium bisulfate product can be directly sold. The effective recovery of the etherification salt residue and hydrolyzed waste sulfuric acid, the waste materials in the production of oxadiargyl, is realized. Compared with the cost of treating the two separately, the effective components in the etherification salt residue and hydrolyzed waste sulfuric acid are fully utilized, which not only reduces the treatment cost of the two, but also solves the treatment difficulties of the two. The above treatment method is simple to operate, and there are basically no secondary pollution products in the treatment process. All production equipment such as containers, cooling and heating equipment, reflux and distillation devices, and filter funnels required in the whole treatment method are basic general equipment in this field, and there are no special requirements. Therefore, this treatment method can be applied to industrial production and can bring significant economic and environmental benefits.

[0032] Example 1 Weigh 120 g of etherification salt residue (with a potassium bromide content of 55.02%) and add it to a 500 mL four-necked flask equipped with an electric stirrer. Then add 25 g of isopropyl alcohol and pure water to the four-necked flask. The amount of pure water added should be such that the concentration of the intermediate product hydrogen bromide reaches 40% - 50%. Then stir for 30 min to fully dissolve and mix the etherification salt residue and isopropyl alcohol evenly. Then place the four-necked flask inside an ice machine and use the ice machine to lower the temperature inside the four-necked flask to below 10°C. Start gradually dropping 250 g of hydrolyzed waste sulfuric acid into the four-necked flask, and always control the temperature inside the four-necked flask to remain below 20°C during the dropping process.

[0033] After the hydrolyzed waste sulfuric acid was added dropwise within 3 h, the ice machine was removed, and the four-necked flask was heated using an electric heating mantle until reflux. After 4 h of reflux reaction, devices required for atmospheric distillation such as an external condenser were connected to the four-necked flask, and atmospheric distillation was started. The distilled fraction was collected. Heating was stopped when the temperature reached 100 °C. The collected fraction started to separate into layers. The crude isopropyl bromide in the lower layer was obtained through liquid separation operation. The obtained lower layer liquid was washed twice with 15 ml and 10 ml of water successively, and 62.8 g of isopropyl bromide product could be obtained. The isopropyl bromide content in this isopropyl bromide product was 98.52%, and the yield was 90.66%, which could meet the purity requirements for recycling and use in the production of oxadiargyl. The remaining solid-liquid mixture in the flask was cooled to below 5 °C, and this solid-liquid mixture was filtered through a sintered glass funnel. The filtered residue was dried to obtain 120.5 g of crude potassium bisulfate. At this time, the purity of the crude potassium bisulfate could not yet reach the selling standard, so it was recycled and awaited subsequent preparation of sellable potassium bisulfate product through refining, purification, and drying. The remaining 136.6 g of filtrate could be used as the acid in the next batch of reactions and recycled together with the hydrolyzed waste sulfuric acid to achieve recycling.

[0034] For the next batch of reaction, 120 g of etherification salt residue (with potassium bromide content of 55.02%) was weighed and added to a 500 mL four-necked flask equipped with an electric stirrer. Then 25 g of isopropyl alcohol was added to the four-necked flask. It should be noted that water is generated during the reaction process itself. In this reaction, recycled filtrate and hydrolyzed waste sulfuric acid would be added later. The two kinds of waste sulfuric acid contain enough water to dissolve the etherification salt residue, so there is no need to add pure water additionally. Then, it was stirred for 30 min to fully dissolve and mix the etherification salt residue and isopropyl alcohol evenly. After that, the four-necked flask was placed inside the ice machine, and the temperature inside the four-necked flask was lowered to below 10 °C using the ice machine. Then, 130 g of the recycled filtrate from the previous batch and 140 g of hydrolyzed waste sulfuric acid were added dropwise to the four-necked flask in sequence. During the dropping process, the temperature inside the four-necked flask was always controlled to be below 20 °C.

[0035] After adding the two kinds of waste sulfuric acid dropwise within 3 h, the temperature was raised to reflux. After 4 h of reflux reaction, atmospheric distillation was started, and the distilled fraction was collected. Heating was stopped when the temperature reached 100 °C. The collected fraction began to separate into layers, and the lower layer of crude isopropyl bromide was obtained by liquid separation. It was washed twice with 15 ml and 10 ml of water in sequence to obtain 64.8 g of isopropyl bromide product. The content of isopropyl bromide in the obtained isopropyl bromide product this time was 98.48%, and the yield was 93.51%. It could be directly recycled for the production of oxyfluorfen. It is worth noting that isopropanol could be obtained by distilling the two washing liquids, and the recycled isopropanol could be reused. The distilled washing liquid could also be repeatedly used to wash the crude isopropyl bromide; the remaining solid-liquid mixture in the flask was cooled to below 5 °C and filtered through a sintered glass funnel. The filtered residue was dried to obtain 128.8 g of crude potassium bisulfate, which was recycled and waiting for subsequent purification and drying. The remaining 145.8 g of filtrate and the recycled filtrate from the previous batch that had not been reused were used together as the acid part in the next batch of reactions to replace the hydrolyzed waste sulfuric acid and were reused to achieve repeated recycling.

[0036] 150 g of the recycled crude potassium bisulfate was weighed and added to a 500 mL four-necked flask equipped with an electric stirrer. Then 150 g of pure water was added to the four-necked flask. The four-necked flask was heated to 80 °C using an electric heating mantle. After stirring for 30 min to ensure complete dissolution, 6 g of activated carbon with a mesh size of 200 was added to adsorb the impurities in the recycled crude potassium bisulfate. 2,4-Dichloro-5-isopropoxynitrobenzene in the etherification salt residue was insoluble in water and could be removed by adsorption with activated carbon. After continuing to stir for 30 min, filtration was carried out while it was hot to obtain a colorless filtrate. The obtained colorless filtrate was placed in an ice machine and slowly cooled to below 5 °C, and then filtered through a sintered glass funnel to obtain white crystals. After drying the white crystals, 98.6 g of potassium bisulfate product could be obtained. The content of potassium bisulfate in the potassium bisulfate product after refining, purification, and drying was 98.84%, meeting the purity requirements of the potassium bisulfate product for external sales. The remaining 173.6 g of recrystallization filtrate after filtration could be recycled for dissolving the recycled crude potassium bisulfate in the next batch.

[0037] Example 2 On the basis of Example 1, for a new batch of reactions, 120 g of etherification salt residue (with a potassium bromide content of 50.31%) was weighed and added to a 500 mL four-necked flask equipped with an electric stirrer. Then 25 g of isopropanol and pure water were added to the four-necked flask. The amount of pure water added was such that the concentration of the intermediate hydrogen bromide reached 40% - 50%. Then, after stirring for 30 min to ensure that the etherification salt residue and isopropanol were completely dissolved and mixed evenly, the four-necked flask was placed inside an ice machine, and the temperature inside the four-necked flask was lowered to below 10 °C using the ice machine. Then, 250 g of hydrolyzed waste sulfuric acid was gradually added dropwise to the four-necked flask, and the temperature inside the four-necked flask was always controlled to be below 20 °C during the dropping process.

[0038] After the hydrolyzed waste sulfuric acid was added dropwise within 3 h, the ice machine was removed, and the four-necked flask was heated using an electric heating mantle until reflux. After 4 h of reflux reaction, devices required for atmospheric distillation such as an external condenser were connected to the four-necked flask, and atmospheric distillation was started. The distilled fractions were collected. Heating was stopped when the temperature reached 100 °C. The collected fractions started to separate into layers. The crude isopropyl bromide in the lower layer was obtained through liquid separation operation. The obtained lower layer liquid was washed twice with 15 ml and 10 ml of water successively, and 56.8 g of isopropyl bromide product was obtained. The isopropyl bromide content in this isopropyl bromide product was 98.72%, and the yield was 89.38%, which could meet the purity requirements for recycling in the production of propyzamide. The remaining solid-liquid mixture in the flask was cooled to below 5 °C, and the solid-liquid mixture was filtered through a sintered glass funnel. The filtered residue was dried to obtain 119.6 g of crude potassium bisulfate. At this time, the purity of the crude potassium bisulfate could not reach the selling standard, and it was recycled and awaited subsequent preparation of sellable potassium bisulfate product through refining, purification, and drying. The remaining 138.5 g of filtrate could be used as the acid in the next batch of reactions and recycled together with the hydrolyzed waste sulfuric acid to achieve recycling.

[0039] For the next batch of reactions, 120 g of etherification salt residue (with a potassium bromide content of 50.31%) was weighed and added to a 500 mL four-necked flask equipped with an electric stirrer. Then, 25 g of isopropyl alcohol was added to the four-necked flask. Next, stirring was carried out for 30 min to fully dissolve and mix the etherification salt residue and isopropyl alcohol evenly. Then, the four-necked flask was placed inside the ice machine, and the temperature inside the four-necked flask was reduced to below 10 °C using the ice machine. Then, 135 g of the filtrate recycled from the previous batch and 135 g of hydrolyzed waste sulfuric acid were added dropwise to the four-necked flask in sequence. During the dropping process, the temperature inside the four-necked flask was always controlled to be below 20 °C.

[0040] After the two kinds of waste sulfuric acids were added dropwise within 3 h, the temperature was raised to reflux. After 4 h of reflux reaction, atmospheric distillation was started, and the distilled fractions were collected. Heating was stopped when the temperature reached 100 °C. The collected fractions started to separate into layers. The crude isopropyl bromide in the lower layer was obtained through liquid separation and washed twice with 15 ml and 10 ml of water successively, and 59.2 g of isopropyl bromide product was obtained. The isopropyl bromide content in the isopropyl bromide product obtained this time was 98.45%, and the yield was 93.40%. The purity reached the requirements for recycling in the production of propyzamide. The remaining solid-liquid mixture in the flask was cooled to below 5 °C, filtered through a sintered glass funnel. The filtered residue was dried to obtain 128.4 g of crude potassium bisulfate. The remaining 148.2 g of filtrate and the filtrate recycled from the previous batch that had not been recycled were continued to be used as the acid part in the next batch of reactions to partially replace the hydrolyzed waste sulfuric acid for recycling to achieve repeated recycling.

[0041] Weigh 150 g of the recovered crude potassium bisulfate and add it to a 500 mL four-necked flask equipped with an electric stirrer. Then add 30 g of pure water and 170 g of the recrystallization filtrate remaining after filtration in Example 1 to the four-necked flask. Use an electric heating mantle to heat the four-necked flask to 80 °C. Stir for 30 min to ensure complete dissolution. Then add 6 g of 200-mesh activated carbon to adsorb the impurities in the recovered crude potassium bisulfate. Continue to stir for 30 min, and then filter while it is hot to obtain a colorless filtrate. Put the obtained colorless filtrate into an ice machine and slowly cool it to below 5 °C. Then filter it through a sintered glass funnel to obtain white crystals. After drying the white crystals, 103.8 g of potassium bisulfate product can be obtained. The content of potassium bisulfate in the potassium bisulfate product after purification and drying this time is 98.34%, meeting the purity requirements of the potassium bisulfate product for external sales. The remaining 215.5 g of recrystallization filtrate after filtration can continue to be used in the next batch to replace part of the pure water and be recycled for dissolving the recovered crude potassium bisulfate.

[0042] Furthermore, it is worth noting that after recycling and reusing the recovered filtrate multiple times to partially replace the hydrolyzed waste sulfuric acid, the recovered filtrate contains too many impurities and is not suitable for continued use. During the reflux reaction and atmospheric distillation processes, some reaction tail gases will be generated, and their main component is volatile hydrobromic acid. The reaction tail gases can be absorbed by water to obtain a hydrobromic acid solution. Repeat the absorption of the reaction tail gases multiple times until the hydrobromic acid solution reaches a certain concentration, and then it can be used to replace the filtrate after multiple cycles of reuse as the acid in the next batch of reactions and be used together with the hydrolyzed waste sulfuric acid, improving the recovery rate of bromine elements and having certain economic benefits.

[0043] To facilitate better understanding of this solution by those skilled in the art, the method adopted by the present invention for determining the content of potassium bisulfate in the potassium bisulfate product is as follows: Weigh 2 g (accurate to 0.0001 g) of the potassium bisulfate product into a 250 mL conical flask, add 100 mL of carbon dioxide-free pure water, shake well, add 2 drops of phenolphthalein indicator solution (10 g / L), and titrate with a sodium hydroxide standard titration solution [C(NaOH) = 0.5 mol / L] until the solution turns pink. After calculation, the content of potassium bisulfate in the potassium bisulfate product can be obtained. Repeat the above steps for a second determination, and take the average of the two parallel determination results to obtain the content of potassium bisulfate in the potassium bisulfate product as 98.72%. Similarly, according to the above steps, the concentration of the potassium bisulfate products obtained in Example 1 and Example 2 can be obtained, which will not be elaborated here. Through experimental determination, the concentrations of the potassium bisulfate products obtained in Example 1 and Example 2 are both greater than 98%, meeting the external sales standard.

[0044] Table 1 is for Figure 1 the result data table corresponding to the gas chromatogram of the isopropyl bromide product shown.

[0045] Table 1: Data sheet of the results of the gas chromatogram of the isopropyl bromide product prepared by a treatment method for by-product etherification salt residue and hydrolyzed waste sulfuric acid of oxadiargyl In the present invention, by comprehensively treating the by-product etherification salt residue and hydrolyzed waste sulfuric acid generated in the production process of oxadiargyl, the two are converted into an isopropyl bromide product that can be used for the production of oxadiargyl and a potassium bisulfate product that can be directly sold. Hydrolyzed waste sulfuric acid is dropped into the mixed solution of etherification salt residue, water and isopropanol. After reflux reaction, atmospheric distillation and cooling filtration, crude isopropyl bromide and crude potassium bisulfate are obtained. After washing with water, refining, purification and drying respectively, the isopropyl bromide product and potassium bisulfate product can be obtained. This treatment method is simple to operate, can simultaneously solve the treatment difficulties of etherification salt residue and hydrolyzed waste sulfuric acid, reduce the treatment cost, realize the effective recovery of the two, make full use of the effective components in the two wastes. The remaining filtrate, recrystallization filtrate and recovered hydrobromic acid during the treatment process can be repeatedly recycled and applied instead of part of the hydrolyzed waste sulfuric acid. There is basically no secondary pollution during the treatment process, and there are no special requirements for production equipment, which can be applied to industrial production, realizing the double improvement of economic benefits and environmental benefits.

[0046] The content recorded in the embodiments of the present invention is only the preferred embodiment of the present invention. It should be noted that those skilled in the art will easily think of other implementation schemes of the present invention after considering the specification and practicing the application disclosed herein. The present invention aims to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include the common general knowledge or conventional technical means in the technical field disclosed by the present invention. The specification and examples are only regarded as exemplary, and the true scope of the present invention is pointed out by the claims.

[0047] It should be understood that the present invention is not limited to the exact structure already described and shown in the drawings, and various modifications and changes can be made without departing from its scope. The above-described embodiments of the present invention do not constitute a limitation on the protection scope of the present invention.

Claims

1. A method for treating etherified salt slag and hydrolysis waste sulfuric acid produced as byproducts of oxadiazon, characterized in that: The following steps are involved: The etherified salt residue, water and isopropanol are mixed and stirred uniformly to obtain a mixed solution in which the etherified salt residue and the isopropanol are dissolved; Adding hydrolyzed waste sulfuric acid dropwise into the mixed solution of the dissolved etherified salt residue and isopropanol, and obtaining a crude isopropyl bromide product after reflux reaction and atmospheric distillation; The residual liquid after the atmospheric distillation is cooled and filtered to obtain a crude potassium hydrogen sulfate product; The crude isopropyl bromide is washed with water to obtain an isopropyl bromide product, and the isopropyl bromide product can be used to produce oxadiazon; The crude potassium bisulfate is refined, purified and dried to obtain a potassium bisulfate product that can be directly sold.

2. The method for treating by-product etherified salt slag and hydrolysis waste sulfuric acid of oxadiazon according to claim 1, characterized in that: The etherified salt slag contains mainly KBr, KHCO3, K2CO3, 2,4-dichloro-5-isopropoxynitrobenzene and water, and the mass contents of KBr, KHCO3, K2CO3, 2,4-dichloro-5-isopropoxynitrobenzene and water are 35-65%, 30-50%, 1-10%, 0.1-3% and 0.5-3%, respectively.

3. The method for treating by-product etherified salt slag and hydrolysis waste sulfuric acid of oxadiazon according to claim 1, characterized in that: The hydrolyzed waste sulfuric acid contains sulfuric acid, isopropanol and water as main components, and the mass contents of the sulfuric acid, isopropanol and water are 50% to 90%, 3 to 30% and 10 to 30% respectively.

4. The method for treating by-product etherified salt slag and hydrolysis waste sulfuric acid of oxadiazon according to claim 1, characterized in that: The mass ratio of the dissolved etherified salt residue, the isopropanol and the hydrolyzed waste sulfuric acid is 1:0.2-0.6:1.5-3.

5. The method for treating by-product etherified salt slag and hydrolysis waste sulfuric acid of oxadiazon according to claim 1, characterized in that: The dropping temperature of the hydrolyzed waste sulfuric acid is maintained below 20° C., and the dropping time is 1 to 3 hours.

6. The method for treating by-product etherified salt slag and hydrolysis waste sulfuric acid of oxadiazon according to claim 1, characterized in that: The reflux reaction time is 2 to 4 hours.

7. The method for treating by-product etherified salt slag and hydrolysis waste sulfuric acid of oxadiazon according to claim 1, characterized in that: When the temperature of the atmospheric distillation reaches 100°C, the heating can be stopped.

8. The method for treating by-product etherified salt slag and hydrolysis waste sulfuric acid of oxadiazon according to claim 1, characterized in that: Also includes: The filtrate after cooling and filtration is used in the next batch of reactions, replacing part of the waste sulfuric acid from hydrolysis and dripping it into the mixed solution of the dissolved etherified salt residue and isopropanol.

9. The method for treating by-product etherified salt slag and hydrolysis waste sulfuric acid of oxadiazon according to claim 8, characterized in that: Also includes: Water is used to absorb the reaction tail gas generated in the reflux reaction and the atmospheric distillation process to obtain hydrobromic acid, and the hydrobromic acid is used to replace the filtrate after multiple cycles of use.

10. A method for treating by-product etherified salt slag and hydrolysis waste sulfuric acid of oxadiazon according to any one of claims 1 to 9, characterized in that: The isopropyl bromide content in the isopropyl bromide product is more than 98%; the potassium hydrogen sulfate content in the potassium hydrogen sulfate product is more than 98%.

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