阅读说明：本技术 一种混合废溶剂的处理方法 (Treatment method of mixed waste solvent ) 是由 李寿丽 史会兵 赵德明 崔勇 郭虎菲 王耀伟 栾波 于 2021-10-29 设计创作，主要内容包括：本发明涉及危废处理技术领域,尤其涉及一种混合废溶剂的处理方法,包括以下步骤：A)将混合废溶剂、水和氧化钙混合,得到混合料液；B)将所述混合料液进行过滤,得到混合溶液；C)将所述混合溶液进行分液,得到甲醇粗液和甲苯粗液；将所述甲醇粗液在甲醇蒸馏釜中进行蒸馏,得到甲醇成品；所述甲醇蒸馏釜的塔顶温度保持在60～70℃；将所述甲苯粗液在甲苯脱水釜中进行蒸馏,蒸馏出的气体进入盐析分层器,分出的上层甲苯返回所述甲苯脱水釜中,当所述甲苯脱水釜的塔顶温度达到105～110℃,得到甲苯成品。本发明提供的处理方法可以有效分离出甲苯和甲醇,并且甲苯和甲醇的回收率和纯度均较高,质量均可达到工业品要求。(The invention relates to the technical field of hazardous waste treatment, in particular to a treatment method of a mixed waste solvent, which comprises the following steps: A) mixing the mixed waste solvent, water and calcium oxide to obtain a mixed feed liquid; B) filtering the mixed material liquid to obtain a mixed solution; C) separating the mixed solution to obtain a methanol crude solution and a toluene crude solution; distilling the methanol crude liquid in a methanol distillation kettle to obtain a methanol finished product; the tower top temperature of the methanol distillation kettle is kept at 60-70 ℃; and distilling the toluene crude liquid in a toluene dehydration kettle, feeding distilled gas into a salting-out delayer, returning the separated upper-layer toluene into the toluene dehydration kettle, and obtaining a toluene finished product when the tower top temperature of the toluene dehydration kettle reaches 105-110 ℃. The treatment method provided by the invention can effectively separate the toluene and the methanol, and the toluene and the methanol have high recovery rate and purity and can meet the requirements of industrial products.)

1. A treatment method of a mixed waste solvent comprises the following steps:

A) mixing the mixed waste solvent, water and calcium oxide to obtain a mixed feed liquid;

B) filtering the mixed material liquid to obtain a mixed solution;

C) separating the mixed solution to obtain a methanol crude solution and a toluene crude solution;

distilling the methanol crude liquid in a methanol distillation kettle to obtain a methanol finished product; the tower top temperature of the methanol distillation kettle is kept at 60-70 ℃;

and distilling the toluene crude liquid in a toluene dehydration kettle, feeding distilled gas into a salting-out delayer, returning the separated upper-layer toluene into the toluene dehydration kettle, and obtaining a toluene finished product when the tower top temperature of the toluene dehydration kettle reaches 105-110 ℃.

2. The process of claim 1, wherein in step a), the mixed waste solvent comprises methanol, toluene, methyl acetate, acetic acid and water.

3. The process according to claim 1, wherein the water content of the mixed waste solvent in the step a) is 0.34 to 13.47%.

4. The process according to claim 1, characterized in that in step a), the quantity of water is calculated according to formula (1):

V_{water (W)}＝M_{Waste solvent}×C_{(methyl acetate + acetic acid)}×3.7 (1)；

In the formula (1), V_{Water (W)}Volume of water added, mL;

M_{waste solvent}Mass of the mixed waste solvent, g;

C_{(methyl acetate + acetic acid)}Is the sum of the mass contents of methyl acetate and acetic acid in the mixed waste solvent.

5. The treatment process according to claim 1, wherein in step a), the amount of calcium oxide is calculated according to formula (2):

M_{calcium oxide}＝M_{Waste solvent}×C_{Acetic acid methyl ester}×0.45+M_{Waste solvent}×C_{Acetic acid}×0.55 (2)；

In the formula (2), M_{Calcium oxide}Mass of calcium oxide added, g;

M_{waste solvent}Mass of the mixed waste solvent, g;

C_{acetic acid methyl ester}The mass content of methyl acetate in the mixed waste solvent is percent;

C_{acetic acid}Is the mass content of acetic acid in the mixed waste solvent.

6. The process according to claim 1, characterized in that in step a), the mixing is stirred mixing;

the mixing temperature is 50-60 ℃, and the mixing time is 1.5-2.5 h.

7. The treatment method according to claim 1, wherein in the step C), the crude methanol solution is distilled in a methanol distillation kettle, when the temperature of the bottom of the methanol distillation kettle reaches 103-105 ℃, the distillation is stopped, and calcium acetate is separated out from the bottom of the methanol distillation kettle;

after the distillation of the crude methanol solution is finished, the method further comprises the following steps:

and cooling the distilled gas to obtain a methanol finished product.

8. The process of claim 7, further comprising, after stopping distillation: and discharging the tower bottom liquid.

9. The process of claim 1, wherein in step C), the salt solution in the salting-out delayer comprises a sodium chloride solution.

10. The treatment method according to claim 1, wherein in the step C), after the temperature of the top of the toluene dehydration kettle reaches 105-110 ℃, the method further comprises the following steps:

and cooling the liquid in the toluene dehydration kettle to obtain a toluene finished product.

Technical Field

The invention relates to the technical field of hazardous waste treatment, in particular to a treatment method of a mixed waste solvent.

Background

Different solvents such as methanol, toluene, methyl acetate, acetic acid, water and the like are used in the process of producing pesticide raw medicines and fine chemicals, the problems of difficult azeotropy and separation and high treatment cost exist, waste solvents are often generated, outsourcing is needed to endanger waste treatment factories to treat the waste solvents, the treatment cost is high, and the development of enterprises is seriously restricted, so that the problem to be solved urgently is developed by the method for quickly and efficiently solving the mixed waste solvents.

Disclosure of Invention

In view of the above, the present invention provides a method for treating a mixed waste solvent, which has high recovery rate and purity of toluene and methanol.

The invention provides a method for treating mixed waste solvent, which comprises the following steps:

A) mixing the mixed waste solvent, water and calcium oxide to obtain a mixed feed liquid;

B) filtering the mixed material liquid to obtain a mixed solution;

C) separating the mixed solution to obtain a methanol crude solution and a toluene crude solution;

distilling the methanol crude liquid in a methanol distillation kettle to obtain a methanol finished product; the tower top temperature of the methanol distillation kettle is kept at 60-70 ℃;

and distilling the toluene crude liquid in a toluene dehydration kettle, feeding distilled gas into a salting-out delayer, returning the separated upper-layer toluene into the toluene dehydration kettle, and obtaining a toluene finished product when the tower top temperature of the toluene dehydration kettle reaches 105-110 ℃.

Preferably, in the step a), the mixed waste solvent includes methanol, toluene, methyl acetate, acetic acid and water.

Preferably, in the step a), the water content of the mixed waste solvent is 0.34% to 13.47%.

Preferably, in step a), the amount of water is calculated according to formula (1):

V_{water (W)}＝M_{Waste solvent}×C_{(methyl acetate + acetic acid)}×3.7 (1)；

In the formula (1), V_{Water (W)}Volume of water added, mL;

M_{waste solvent}Mass of the mixed waste solvent, g;

C_{(methyl acetate + acetic acid)}Is the sum of the mass contents of methyl acetate and acetic acid in the mixed waste solvent.

Preferably, in step a), the amount of calcium oxide is calculated according to formula (2):

M_{calcium oxide}＝M_{Waste solvent}×C_{Acetic acid methyl ester}×0.45+M_{Waste solvent}×C_{Acetic acid}×0.55 (2)；

In the formula (2), M_{Calcium oxide}Mass of calcium oxide added, g;

M_{waste solvent}Mass of the mixed waste solvent, g;

C_{acetic acid methyl ester}The mass content of methyl acetate in the mixed waste solvent is percent;

C_{acetic acid}Is the mass content of acetic acid in the mixed waste solvent.

Preferably, in the step A), the mixing is stirring mixing;

the mixing temperature is 50-60 ℃, and the mixing time is 1.5-2.5 h.

Preferably, in the step C), distilling the methanol crude liquid in a methanol distillation kettle, stopping distilling when the temperature of the bottom of the methanol distillation kettle reaches 103-105 ℃, and separating out calcium acetate at the bottom of the methanol distillation kettle;

after the distillation of the crude methanol solution is finished, the method further comprises the following steps:

and cooling the distilled gas to obtain a methanol finished product.

Preferably, after the distillation is stopped, the method further comprises the following steps: and discharging the tower bottom liquid.

Preferably, in step C), the salt solution in the salting-out delayer comprises a sodium chloride solution.

Preferably, in the step C), when the temperature of the top of the toluene dehydration kettle reaches 105 to 110 ℃, the method further comprises the following steps:

and cooling the liquid in the toluene dehydration kettle to obtain a toluene finished product.

The invention provides a method for treating mixed waste solvent, which comprises the following steps: A) mixing the mixed waste solvent, water and calcium oxide to obtain a mixed feed liquid; B) filtering the mixed material liquid to obtain a mixed solution; C) separating the mixed solution to obtain a methanol crude solution and a toluene crude solution; distilling the methanol crude liquid in a methanol distillation kettle to obtain a methanol finished product; the tower top temperature of the methanol distillation kettle is kept at 60-70 ℃; and distilling the toluene crude liquid in a toluene dehydration kettle, feeding distilled gas into a salting-out delayer, returning the separated upper-layer toluene into the toluene dehydration kettle, and obtaining a toluene finished product when the tower top temperature of the toluene dehydration kettle reaches 105-110 ℃. The treatment method provided by the invention can effectively separate the toluene and the methanol, and the toluene and the methanol have high recovery rate and purity and can meet the requirements of industrial products. Meanwhile, the separated sodium chloride solution and the calcium hydroxide solution can be recycled.

Drawings

Fig. 1 is a flow chart of a treatment process of a mixed waste solvent according to an embodiment of the present invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a method for treating mixed waste solvent, which comprises the following steps:

A) mixing the mixed waste solvent, water and calcium oxide to obtain a mixed feed liquid;

B) filtering the mixed material liquid to obtain a mixed solution;

C) separating the mixed solution to obtain a methanol crude solution and a toluene crude solution;

distilling the methanol crude liquid in a methanol distillation kettle to obtain a methanol finished product; the tower top temperature of the methanol distillation kettle is kept at 60-70 ℃;

and distilling the toluene crude liquid in a toluene dehydration kettle, feeding distilled gas into a salting-out delayer, returning the separated upper-layer toluene into the toluene dehydration kettle, and obtaining a toluene finished product when the tower top temperature of the toluene dehydration kettle reaches 105-110 ℃.

The invention firstly mixes the mixed waste solvent, water and calcium oxide to obtain mixed feed liquid.

In certain embodiments of the present invention, the mixed waste solvent comprises methanol, toluene, methyl acetate, acetic acid, and water.

In certain embodiments of the present invention, the water content of the mixed waste solvent is 0.34% to 13.47%. In certain embodiments, the water content of the mixed waste solvent is 1.92% or 0.5%.

In certain embodiments of the present invention, the mixed waste solvent has a methanol content of 89.36% by mass, a toluene content of 7.65% by mass, a methyl acetate content of 0.68% by mass, an acetic acid content of 0.39% by mass, and a water content of 1.92% by mass. In certain embodiments of the present invention, the mixed waste solvent has a methanol content of 0.26% by mass, a toluene content of 79.90% by mass, a methyl acetate content of 1.72% by mass, an acetic acid content of 17.62% by mass, and a water content of 0.5% by mass.

In some embodiments of the invention, the amount of water is calculated according to equation (1):

V_{water (W)}＝M_{Waste solvent}×C_{(methyl acetate + acetic acid)}×3.7 (1)；

In the formula (1), V_{Water (W)}Volume of water added, mL;

M_{waste solvent}Mass of the mixed waste solvent, g;

C_{(methyl acetate + acetic acid)}Is the sum of the mass contents of methyl acetate and acetic acid in the mixed waste solvent.

In certain embodiments of the invention, the amount of calcium oxide is calculated according to equation (2):

M_{calcium oxide}＝M_{Waste solvent}×C_{Acetic acid methyl ester}×0.45+M_{Waste solvent}×C_{Acetic acid}×0.55 (2)；

In the formula (2), M_{Calcium oxide}Mass of calcium oxide added, g;

M_{waste solvent}Mass of the mixed waste solvent, g;

C_{acetic acid methyl ester}The mass content of methyl acetate in the mixed waste solvent is percent;

C_{acetic acid}Is the mass content of acetic acid in the mixed waste solvent.

In certain embodiments of the invention, the calcium oxide is powdered calcium oxide.

In certain embodiments of the invention, the mixing is stirred mixing.

In some embodiments of the invention, the mixing temperature is 50-60 ℃ and the mixing time is 1.5-2.5 h. In certain embodiments, the temperature of the mixing is 50 ℃ or 60 ℃. In certain embodiments, the time of mixing is 2 hours.

In certain embodiments of the invention, the mixing is performed in a stirred tank.

According to the invention, after the mixed waste solvent, calcium oxide and water are mixed, methyl acetate is hydrolyzed under an alkaline condition and reacts with calcium hydroxide to generate calcium acetate and methanol.

According to the invention, the mixed waste solvent, calcium oxide and water are mixed, so that methyl acetate and acetic acid in the mixed waste solvent can be removed.

The obtained mixed feed liquid comprises solid matters of calcium oxide and calcium hydroxide.

And after the mixed material liquid is obtained, filtering the mixed material liquid to obtain a mixed solution. The method of filtration is not particularly limited in the present invention, and a filtration method known to those skilled in the art may be used. The filtration is used for removing solid substances of calcium oxide and calcium hydroxide in the mixed feed liquid. In certain embodiments of the invention, the solid materials calcium oxide and calcium hydroxide may be recycled.

In the invention, the upper layer of the obtained mixed solution is the crude toluene solution, and the lower layer of the obtained mixed solution is the crude methanol solution.

And after a mixed solution is obtained, separating the mixed solution to obtain a methanol crude liquid and a toluene crude liquid.

In certain embodiments of the invention, the liquid separation is performed in a liquid separation tank.

In the invention, the methanol crude liquid is distilled in a methanol distillation kettle to obtain a methanol finished product.

The tower top temperature of the methanol distillation kettle is kept at 60-70 ℃. In certain embodiments of the invention, the overhead temperature of the methanol still is maintained at 64.6 ℃ or 70 ℃.

In some embodiments of the present invention, the crude methanol may be pumped into the methanol still via a first transfer pump. The structure and source of the first delivery pump are not particularly limited, and a delivery pump known to those skilled in the art may be used.

And heating the kettle interlayer of the methanol distillation kettle by using steam, controlling reflux at the tower top by controlling the flow rate of cooling water of a condenser, and keeping the temperature at the tower top at 60-70 ℃.

In some embodiments of the invention, the crude methanol solution is distilled in a methanol distillation still, and when the temperature of the bottom of the methanol distillation still reaches 103-105 ℃, the distillation is stopped, and calcium acetate is separated out from the bottom of the methanol distillation still and can be used as a snow melting agent.

In certain embodiments of the invention, the distillation is stopped when the bottom temperature of the methanol still reaches 103 ℃ or 105 ℃.

In some embodiments of the present invention, after the distillation of the crude methanol solution is completed, the method further comprises:

and cooling the distilled gas to obtain a methanol finished product.

In certain embodiments of the invention, the cooling is performed in a first condensate cooler. The structure and source of the first condensing cooler are not particularly limited in the present invention, and those known to those skilled in the art may be used.

In certain embodiments of the present invention, after stopping distillation, further comprising: and discharging the tower bottom liquid. In some embodiments, after the discharging of the bottom liquid, the method further comprises: the salt is removed by filtration, the content of the components in the filtrate is analyzed, and then the filtrate is combined into the next batch of mixed waste solvent for treatment.

In the invention, the crude toluene liquid is distilled in a toluene dehydration kettle, the distilled gas enters a salting-out delayer, the separated toluene on the upper layer returns to the toluene dehydration kettle, and when the temperature of the top of the toluene dehydration kettle reaches 105-110 ℃, a toluene finished product is obtained.

In certain embodiments of the present invention, the crude toluene liquid may be pumped into the toluene dehydration kettle via a second transfer pump. The structure and source of the second delivery pump are not particularly limited, and those well known to those skilled in the art can be used.

In certain embodiments of the invention, the overhead temperature of the toluene dehydration kettle reaches 105 ℃ or 108.5 ℃ to obtain the finished toluene product.

In certain embodiments of the invention, the distilled gas is cooled and then enters a salting-out demixer. In certain embodiments of the invention, the cooling is performed in a second condensate cooler. The structure and source of the second condensing cooler are not particularly limited in the present invention, and those known to those skilled in the art can be used.

In certain embodiments of the invention, the salt solution in the salting-out delaminator is a sodium chloride solution. In certain embodiments, the concentration of the sodium chloride solution is 20 wt%.

The method can further remove the methanol in the toluene crude liquid by adopting a salting-out delayer.

In some embodiments of the present invention, after the temperature of the top of the toluene dehydration kettle reaches 105 to 110 ℃, the method further includes:

and cooling the liquid in the toluene dehydration kettle to obtain a toluene finished product.

In certain embodiments of the invention, the cooling is performed in a chiller. The present invention is not particularly limited as to the structure and source of the cooler, and any cooler known to those skilled in the art may be used.

In some embodiments of the invention, the distilled gas enters a salting-out demixer, and the lower layer solution separated out is water, which can be mixed into the salt solution for reuse.

The source of the above-mentioned raw materials is not particularly limited in the present invention, and may be generally commercially available.

Fig. 1 is a flow chart of a treatment process of a mixed waste solvent according to an embodiment of the present invention. Wherein, mixed useless solvent corresponds the miscella in figure 1, and the filler hole is used for adding calcium oxide, and 1 is stirred tank, 2 is the branch fluid reservoir, and 3 is the thick fluid reservoir of methyl alcohol, and 4 is the thick fluid reservoir of toluene, and 5 is the methyl alcohol stills, and 6 is the toluene dehydration cauldron, and 7 is first condensation cooler, and 8 is the second condensation cooler, and 9 is the layering ware of salting out, and 10 is first delivery pump, and 11 is the second delivery pump, and 12 is methyl alcohol finished product storage tank, and 13 is toluene finished product storage tank, and 14 is the cooler, and 15 is the filter.

In order to further illustrate the present invention, the following will describe the method for treating a mixed waste solvent according to the present invention in detail with reference to the following examples, which should not be construed as limiting the scope of the present invention.

The starting materials used in the following examples are all commercially available.

Example 1

The treatment of the mixed waste solvent is carried out according to the process flow diagram shown in figure 1:

the mixed waste solvent comprises methanol, toluene, methyl acetate, acetic acid and water, wherein the water content of the mixed waste solvent is 1.92%, the mass content of the methanol is 89.36%, the mass content of the toluene is 7.65%, the mass content of the methyl acetate is 0.68%, and the mass content of the acetic acid is 0.39%;

adding 15.91mL of water into a stirring kettle filled with 800g of mixed waste solvent, adding 3.516g of powdered calcium oxide into a feeding hopper, controlling the temperature of the stirring kettle at 50 ℃, and stirring for 2 hours to obtain mixed feed liquid;

filtering the mixed material liquid to obtain a mixed solution;

inputting the mixed solution into a liquid separation tank for liquid separation, wherein the lower-layer solution enters a methanol crude liquid tank, and the upper-layer solution enters a toluene crude liquid tank;

pumping the methanol crude liquid in the methanol crude liquid tank into a methanol distillation kettle through a first delivery pump, heating the kettle interlayer by using steam, controlling reflux at the tower top by controlling the cooling water flow of a condenser, and keeping the temperature at the tower top at 64.6 ℃; when the temperature of the bottom of the methanol distillation kettle reaches 103 ℃, stopping distillation, and separating out calcium acetate which can be used as a snow-melting agent; after the crude methanol liquid is distilled, cooling the distilled gas in a first condensing cooler to obtain a finished methanol product, and feeding the finished methanol product into a finished methanol product storage tank; discharging tower bottom liquid, filtering to remove salt, analyzing component content in filtrate, and then merging the filtrate into the next batch of mixed waste solvent for treatment;

pumping the toluene crude liquid in the toluene crude liquid tank into a toluene dehydration kettle through a second conveying pump, distilling in the toluene dehydration kettle, cooling the distilled gas in a second condensation cooler, then feeding the cooled gas into a salting-out delayer, returning the separated toluene in the upper layer into the toluene dehydration kettle, cooling the liquid in the toluene dehydration kettle in the cooler when the temperature of the tower top of the toluene dehydration kettle reaches 105 ℃, obtaining a toluene finished product, and feeding the toluene finished product into a toluene finished product storage tank; the salt solution in the salting-out delayer is 20 wt% of sodium chloride solution; the separated lower layer solution is water and can be mixed into the salt solution for recycling.

The finished methanol product in the finished methanol product storage tank is detected, and the experimental result shows that the purity of the finished methanol product is 99.3 percent, and the recovery rate of the methanol is 93.5 percent; the toluene finished product in the toluene finished product storage tank is detected, and the experimental result shows that the purity of the toluene finished product is 99.5%, and the recovery rate of the toluene is 95.6%.

Example 2

The treatment of the mixed waste solvent is carried out according to the process flow diagram shown in figure 1:

the mixed waste solvent comprises methanol, toluene, methyl acetate, acetic acid and water, wherein the water content of the mixed waste solvent is 0.5 percent, the mass content of the methanol is 0.26 percent, the mass content of the toluene is 79.90 percent, the mass content of the methyl acetate is 1.72 percent, and the mass content of the acetic acid is 17.62 percent;

adding 468.4mL of water into a stirring kettle filled with 800g of mixed waste solvent, adding 70.99g of powdered calcium oxide into a feeding hopper, controlling the stirring kettle at 60 ℃, and stirring for 2 hours to obtain mixed feed liquid;

filtering the mixed material liquid to obtain a mixed solution;

inputting the mixed solution into a liquid separation tank for liquid separation, wherein the lower-layer solution enters a methanol crude liquid tank, and the upper-layer solution enters a toluene crude liquid tank;

pumping the methanol crude liquid in the methanol crude liquid tank into a methanol distillation kettle through a first delivery pump, heating the kettle interlayer by using steam, controlling reflux at the tower top by controlling the cooling water flow of a condenser, and keeping the temperature at the tower top at 70 ℃; when the temperature of the bottom of the methanol distillation kettle reaches 105 ℃, stopping distillation, and separating out calcium acetate which can be used as a snow-melting agent; after the crude methanol liquid is distilled, cooling the distilled gas in a first condensing cooler to obtain a finished methanol product, and feeding the finished methanol product into a finished methanol product storage tank; discharging tower bottom liquid, filtering to remove salt, analyzing component content in filtrate, and then merging the filtrate into the next batch of mixed waste solvent for treatment;

pumping the toluene crude liquid in the toluene crude liquid tank into a toluene dehydration kettle through a second conveying pump, distilling in the toluene dehydration kettle, cooling the distilled gas in a second condensation cooler, then feeding the cooled gas into a salting-out delayer, returning the separated toluene in the upper layer into the toluene dehydration kettle, cooling the liquid in the toluene dehydration kettle in the cooler when the temperature of the top of the toluene dehydration kettle reaches 108.5 ℃, thus obtaining a toluene finished product, and feeding the toluene finished product into a toluene finished product storage tank; the salt solution in the salting-out delayer is 20 wt% of sodium chloride solution; the separated lower layer solution is water and can be mixed into the salt solution for recycling.

The finished methanol product in the finished methanol product storage tank is detected, and the experimental result shows that the purity of the finished methanol product is 99.4 percent, and the recovery rate of the methanol is 93.2 percent; the toluene finished product in the toluene finished product storage tank is detected, and the experimental result shows that the purity of the toluene finished product is 99.6%, and the recovery rate of the toluene is 95.7%.

The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.