Improved vulcanization accelerator production method

Abstract

The invention discloses an improved vulcanization accelerator production method, which comprehensively improves the mother liquor wastewater treatment flow aiming at the characteristics of overhigh COD and ammonia nitrogen content of mother liquor wastewater, overhigh treatment difficulty, low product recycling rate and the like in the production process of a rubber accelerator. Comprising the following steps: recovering excessive carbon disulfide by heating and evaporating a reaction system, adding a small amount of active agent and soluble zinc salt into reaction slurry without carbon disulfide, preserving heat for corresponding time after reaching a titration end point, and centrifugally separating materials and mother liquor; according to the method, the recovery rate of the accelerant product is increased by 6-8%, the COD content and the ammonia nitrogen content in the mother liquor wastewater can be remarkably reduced, the subsequent wastewater treatment process is simplified, the mother liquor recycling frequency is increased, and the economic benefits and the environmental benefits of enterprises are increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of rubber vulcanization accelerator production, and particularly relates to an improved production method of vulcanization accelerator. Background Art

[0002] With the rapid development of the rubber industry, the research and production of rubber vulcanization accelerators have received extensive attention. However, due to factors such as excessive raw material input and low chemical reaction conversion rate, a large amount of mother liquor with a COD exceeding 1000 mg / L and an ammonia nitrogen content of 6000 - 8000 ppm is generated during the production of accelerators. Recycling such high-COD and high-ammonia-nitrogen mother liquor will lead to a decrease in the dispersibility of raw materials in the slurry, making it difficult to ensure continuous and stable production; direct discharge will cause water eutrophication, heavy metal and COD enrichment, seriously damaging the ecological balance. Traditional wastewater treatment methods have complex processes and relatively high treatment costs. Therefore, developing an economical, practical, and safe treatment method for high-COD and high-ammonia-nitrogen wastewater has become an important topic at present, which is of great significance for improving production efficiency, increasing enterprise benefits, and promoting process innovation. Currently, high-ammonia-nitrogen wastewater removal technologies usually include biochemical method, stripping method, steam stripping method, ion exchange method, chemical precipitation method, etc. Among them, the steam stripping method has a relatively high removal rate of ammonia nitrogen and good technical maturity, and is commonly used to treat high-concentration ammonia-nitrogen wastewater (ammonia nitrogen content 500 - 10000 ppm). However, the traditional steam stripping ammonia removal technology has a large steam consumption and high energy consumption for treating wastewater.

[0003] For example, during the production of vulcanization accelerators ZDMC / ZDEC (zinc dimethyldithiocarbamate / zinc diethyldithiocarbamate), organic amines (dimethylamine, diethylamine), carbon disulfide, and zinc compounds (zinc oxide) directly generate accelerator product powder through stirring in a liquid-phase reaction system. After centrifugal separation, the average COD of the mother liquor of ZDMC is in the range of 28000 - 35000 mg / L, and the average ammonia nitrogen is in the range of 3000 - 4000 ppm; the average COD of the mother liquor of ZDEC is in the range of 31000 - 46000 mg / L, and the average ammonia nitrogen is in the range of 1500 - 2500 ppm. Unreacted organic amines, intermediate reaction products of organic amines and carbon disulfide such as dithiocarbamic acid are enriched in the mother liquor, resulting in a low product yield, and the COD and ammonia nitrogen content of the mother liquor seriously exceeding the standard; volatile organic amines diffuse in the production workshop, with a strong odor in the working environment, affecting human health; the treatment process of the mother liquor wastewater consumes complex chemical raw materials, generates a large amount of low-quality by-product sodium salts, and has low treatment efficiency, greatly increasing the treatment cost. Summary of the Invention

[0004] In view of the characteristics in the prior art that the content of COD and ammonia nitrogen in the mother liquor wastewater during the production process of accelerators is too high, the treatment difficulty is too great, and the product recovery rate is relatively low, the present invention discloses an improved production method of vulcanization accelerators, aiming to improve the product yield, reduce the content of pollutants in the mother liquor wastewater, and simplify the subsequent process of wastewater treatment.

[0005] The technical solution of the present invention is as follows: An improved production method of vulcanization accelerators, comprising the following steps: (1) For the accelerator reaction slurry that has ended the heat preservation reaction under suitable temperature conditions, use the jacket device in the reaction kettle to raise the temperature and keep it warm for a certain period of time, so that the unreacted carbon disulfide evaporates and separates from the reaction slurry; (2) Use a negative pressure induced draft cooling recovery device to collect the carbon disulfide evaporated and separated in step (1) to obtain a reaction slurry from which carbon disulfide has been removed; (3) Add a certain amount of active agent to the reaction slurry in step (2) and stir well until it is completely dissolved; (4) Add a quantitative soluble zinc salt to the reaction slurry in step (3) in batches at a certain speed through a dropping control device, and keep it warm for a period of time after reaching the titration end point; (5) Use condensed water to cool down the reaction slurry in step (4), and separate the reaction slurry through a centrifugal device to obtain a high-recovery accelerator product and a mother liquor with low COD and low ammonia nitrogen content.

[0006] Further, in step (1), the material ratio in the accelerator reaction slurry is: the molar ratio of organic amine, carbon disulfide, and zinc oxide is 1:1.0 - 1.3:0.45 - 0.6, the type of organic amine is any one of dimethylamine and diethylamine, the heat preservation temperature is 30 - 40 °C, and the heat preservation time is 3 - 6 h.

[0007] Further, in step (1), the reaction kettle is heated to 60 - 80 °C.

[0008] Further, in step (1), the heat preservation time is 1 - 2 h.

[0009] Further, in step (3), the type of active agent is one or several of sodium dodecylbenzenesulfonate and tallow oil.

[0010] Further, in step (3), the concentration of the active agent in the reaction slurry is 0.1 - 0.15 g / L.

[0011] Further, in step (4), the type of soluble zinc salt is one or several of zinc chloride, zinc nitrate, and zinc acetate.

[0012] Further, in the step (4), the concentration of the soluble zinc salt in the reaction slurry is 1.6 - 3 g equivalent of Zn 2 + / L.

[0013] Further, in the step (4), the soluble zinc salt is added in 1 - 4 batches.

[0014] Further, in the step (4), the time interval between each batch addition of the soluble zinc salt is 15 - 30 min.

[0015] Further, in the step (4), the addition rate of the soluble zinc salt is 100 - 500 g equivalent Zn 2+ / min.

[0016] Further, in the step (4), the soluble zinc salt can be added in solid or solution form.

[0017] Further, in the step (4), the specified pH end point is 5 - 7.

[0018] Further, in the step (4), the heat preservation time is 0.5 - 1 h.

[0019] Further, in the step (5), the reaction slurry is cooled to 30 - 40 °C.

[0020] The present invention also provides an environmental protection treatment method for the high - COD and high - ammonia - nitrogen mother liquor in the production of vulcanization accelerators, including the following steps: (1) For the accelerator reaction slurry that has completed the heat - preservation reaction under appropriate temperature conditions, use the jacket device in the reaction kettle to raise the temperature and keep it warm for a certain time to evaporate and separate the unreacted carbon disulfide from the reaction slurry; (2) Use a negative - pressure induced - draft cooling and recovery device to collect the carbon disulfide evaporated and separated in step (1) to obtain the reaction slurry from which carbon disulfide has been removed; (3) After the reaction slurry has removed carbon disulfide, pass condensed water circulation in the jacket device of the reaction kettle. After the temperature of the reaction slurry drops to 30 °C, transfer it to a centrifugal device to separate the accelerator product from the slurry, obtaining the accelerator product A and the first mother liquor. At this time, the COD in the first mother liquor is 28000 - 35000 mg / L and the ammonia - nitrogen is 3000 - 4000 ppm; (4) Add a certain amount of surfactant to the first mother liquor in step (3). The surfactant is selected from one or both of sodium dodecylbenzenesulfonate and tallow oil, with a concentration of 0.1 - 0.15 g / L, and stir well until completely dissolved; (5) Add a quantitative soluble zinc salt in batches at a certain speed to the first mother liquor in step (4) through a dropping control device. The types of soluble zinc salts are one or several of zinc chloride, zinc nitrate, and zinc acetate. The concentration of the soluble zinc salt in the mother liquor is 1.6 - 3 g equivalents of Zn 2+ / L. After reaching the titration end point with a pH of 5 - 7, keep it warm for a period of time; (6) Use condensed water to cool down the reaction slurry in step (5) to 30°C, and separate it through a centrifugal device to obtain accelerator product B and a second mother liquor with low COD and low ammonia nitrogen content; Combine accelerator products A and B; The COD content in the second mother liquor is less than 1000 mg / L, and the ammonia nitrogen is less than 500 ppm, which can be recycled in the accelerator reaction system or subjected to subsequent wastewater environmental protection treatment.

[0021] Beneficial effects: After the main chemical reaction process of the accelerator ends, by treating the mother liquor after filtration or directly adding a small amount of active agent and soluble zinc salt to the slurry in the accelerator reaction system respectively to change part of the chemical reaction process. Among them, the active agent can improve the dispersibility of zinc compounds and soluble zinc salts in the reaction slurry, and the soluble zinc salt promotes the conversion of unreacted dithiocarbamic acid into accelerator products. On the one hand, these measures can improve the yield of accelerator products (increase by 6 - 8%), increasing the product benefit in a single batch production process; On the other hand, it can quantitatively remove high COD and high ammonia nitrogen in the mother liquor, reducing the average COD of the mother liquor of ZDMC and ZDEC to <1000 mg / L and the average ammonia nitrogen to <500 ppm. This is conducive to increasing the number of times the mother liquor is recycled and reused, simplifying the subsequent wastewater treatment process, reducing the input of chemical raw materials in the wastewater treatment process, and without generating a large amount of by-product sodium salts, improving the working environment, enhancing labor efficiency, and having obvious cost reduction and efficiency improvement effects, significantly enhancing the economic and environmental benefits of the enterprise. Specific embodiments

[0022] The following further clarifies the present invention in combination with specific embodiments. It should be understood that the following specific embodiments are only used to illustrate and explain the present invention and are not used to limit the protection scope of the present invention.

[0023] Example 1 (1) Add approximately 2.7 cubic meters of water into the reaction kettle. Then, put 500 kg of industrial dimethylamine (40% aqueous solution) into the reaction kettle. Next, add a certain amount of zinc oxide, start the stirring inside the kettle, and then dropwise add carbon disulfide. The molar ratio of dimethylamine, carbon disulfide, and zinc oxide is 1:1.1:0.45. After the reaction system reacts and is kept warm at 30 °C for 4 hours, the resulting reaction slurry is a mixture of accelerator powder ZDMC and mother liquor. Then, introduce high-temperature steam into the jacket device inside the reaction kettle. The reaction slurry exchanges heat with the high-temperature steam. After the high-temperature steam condenses, it is discharged through the steam trap. The temperature of the reaction slurry rises. After reaching 65 °C, it is kept warm for 1 hour. The unreacted carbon disulfide in the slurry evaporates due to heat and continuously escapes in the form of gas, realizing the separation of carbon disulfide from the reaction slurry; (2) The carbon disulfide vapor escaping from the reaction slurry continuously rises and gathers above the inside of the reaction kettle. Due to the temperature decrease, it condenses into a liquid, is captured by the negative-pressure induced draft cooling recovery device, and collected in the carbon disulfide recovery tank. The reaction slurry with carbon disulfide removed is obtained inside the reaction kettle; (3) Add 400 g of sodium dodecylbenzenesulfonate to the reaction slurry with carbon disulfide removed in step (2) at one time, and make the active agent fully dissolve and disperse evenly in the slurry through the stirring device inside the reaction kettle, so that the concentration of the active agent in the reaction slurry reaches 0.11 g / L; (4) Feed a certain amount of solid powder of zinc chloride into the raw material tank. The raw material tank is connected to the dropping control device through a pipeline network. Adjust the speed of the dropping control device to 100 g equivalent of Zn 2+ / min, and add it to the reaction kettle in two batches. The time interval between additions is 15 min. Make zinc chloride disperse evenly in the reaction slurry through the stirring device inside the reaction kettle and then fully react. The pH at the titration end point is 7. At this time, the concentration of equivalent Zn 2+ in the reaction slurry is 1.7 g / L, and the reaction slurry is kept warm for 0.5 h; (5) After the reaction slurry finishes keeping warm, introduce condensed water circulation into the jacket device inside the reaction kettle. After the temperature of the reaction slurry drops to 35 °C, transfer it to the centrifugal device to separate the accelerator product from the mother liquor. The accelerator product is obtained as the finished product ZDMC after being dried by high-temperature vacuum evaporation and pulverized.

[0024] Example 2

[0025] (1) Add approximately 2.7 cubic meters of water to the reactor. Charge 530 kg of industrial diethylamine into the reactor, then add a certain amount of zinc oxide. Start the agitation inside the reactor, and then add carbon disulfide dropwise. The molar ratio of diethylamine, carbon disulfide, and zinc oxide is 1:1.2:0.5. After the reaction system reacts and is kept at 35 °C for 5 hours, the resulting reaction slurry is a mixture of accelerator powder ZDEC and mother liquor. Pass high-temperature steam into the jacket device of the reactor, and the reaction slurry exchanges heat with the high-temperature steam. After the high-temperature steam condenses, it is discharged through a steam trap, and the temperature of the reaction slurry rises. After reaching 70 °C, it is kept warm for 1.5 hours. The unreacted carbon disulfide evaporates due to heat and continuously escapes in the form of gas, realizing the separation of carbon disulfide from the reaction slurry; (2) The carbon disulfide vapor escaping from the reaction slurry continuously rises and accumulates above the inside of the reactor. Due to the temperature drop, it condenses into a liquid and is captured by the negative-pressure induced air cooling and recovery device and collected in the carbon disulfide recovery tank. The reaction slurry from which carbon disulfide has been removed is obtained inside the reactor; (3) Add 450 g of tallow oil to the reaction slurry from which carbon disulfide has been removed in step (2) at one time, and make the active agent dissolve and disperse evenly in the slurry through the agitation device inside the reactor, so that the concentration of the active agent in the reaction slurry reaches 0.13 g / L; (4) Charge zinc nitrate solid powder into the raw material tank. The raw material tank is connected to a dropping control device through a pipeline network. Adjust the speed of the dropping control device to 200 g equivalents of Zn 2+ / min, and add it in two times with an interval of 20 minutes. After zinc nitrate is dispersed evenly in the reaction slurry through the agitation device inside the reactor and fully reacts, the pH at the titration end point is 6.5. At this time, the concentration of Zn 2+ in the reaction slurry is 2.3 g / L, and the reaction slurry is kept warm for 0.5 h; (5) After the reaction slurry finishes keeping warm, pass condensed water circulation into the jacket device of the reactor. After the temperature of the reaction slurry drops to 35 °C, transfer it to a centrifugal device to separate the accelerator product from the mother liquor. The accelerator product is obtained as the finished product ZDEC after being dried by high-temperature vacuum evaporation and pulverized.

[0026] Example 3

[0027] (1) Add approximately 2.7 cubic meters of water into the reaction kettle, put 550 kg of industrial dimethylamine into the reaction kettle, then add a certain amount of zinc oxide, start the stirring inside the kettle, and then dropwise add carbon disulfide. The molar ratio of dimethylamine, carbon disulfide, and zinc oxide is 1:1.3:0.6. After the reaction system reacts and is kept warm at 40°C for 5 hours, the resulting reaction slurry is a mixture of accelerator powder ZDMC and mother liquor. Pass high-temperature steam into the jacket device of the reaction kettle, and the reaction slurry exchanges heat with the high-temperature steam. After the high-temperature steam condenses, it is discharged through the steam trap, and the temperature of the reaction slurry rises. After reaching 75°C, it is kept warm for 2 hours. The unreacted carbon disulfide evaporates due to heat and continuously escapes in the form of gas, realizing the separation of carbon disulfide from the reaction slurry; (2) The carbon disulfide vapor escaping from the reaction slurry continuously rises and gathers above the inside of the reaction kettle. Due to the temperature drop, it condenses into a liquid, is captured by the negative pressure induced air cooling recovery device, and collected in the carbon disulfide recovery tank. The reaction slurry from which carbon disulfide has been removed is obtained inside the reaction kettle; (3) Add 500 g of sodium dodecylbenzenesulfonate to the reaction slurry from which carbon disulfide has been removed in step (2) at one time, and make the surfactant fully dissolve and disperse evenly in the slurry through the stirring device inside the reaction kettle, so that the concentration of the surfactant in the reaction slurry reaches 0.14 g / L; (4) Feed the zinc chloride solution into the raw material tank. The raw material tank is connected to the dropping control device through a pipeline network. Adjust the speed of the dropping control device to 300 g equivalent of Zn 2+ / min, and add it in two times with an interval of 20 min between the addition times. Make the zinc chloride disperse evenly in the reaction slurry through the stirring device inside the reaction kettle and then fully react. The pH at the titration end point is 6. At this time, the concentration of equivalent Zn 2+ in the reaction slurry is 2.6 g / L, and the reaction slurry is kept warm for 1 h; (5) After the reaction slurry finishes keeping warm, pass condensed water circulation into the jacket device of the reaction kettle. After the temperature of the reaction slurry drops to 30°C, transfer it to the centrifugal device to separate the accelerator product from the mother liquor. The accelerator product is obtained as the finished product ZDMC after high-temperature vacuum evaporation to dryness and pulverization treatment.

[0028] Comparative Example 1 (1) Add approximately 2.7 cubic meters of water into the reaction kettle. Put 550 kg of industrial dimethylamine into the reaction kettle, then add a certain amount of zinc oxide. Start the stirring inside the kettle, and then dropwise add carbon disulfide. The molar ratio of dimethylamine, carbon disulfide, and zinc oxide is 1:1.3:0.6. After the reaction system reacts and is kept warm at 40 °C for 5 hours, the resulting reaction slurry is a mixture of accelerator powder ZDMC and mother liquor. Pass high-temperature steam into the jacket device of the reaction kettle. The reaction slurry exchanges heat with the high-temperature steam. After the high-temperature steam condenses, it is discharged through the steam trap. The temperature of the reaction slurry rises. After reaching 75 °C, it is kept warm for 2 hours. The unreacted carbon disulfide evaporates due to heat and continuously escapes in the form of gas, realizing the separation of carbon disulfide from the reaction slurry; (2) The carbon disulfide vapor escaping from the reaction slurry continuously rises and gathers above the interior of the reaction kettle. It condenses into a liquid due to temperature reduction and is captured by the negative-pressure induced air cooling and recovery device and collected in the carbon disulfide recovery tank. The reaction slurry with carbon disulfide removed is obtained inside the reaction kettle; (3) After the reaction slurry removes carbon disulfide, pass condensed water circulation into the jacket device of the reaction kettle. After the temperature of the reaction slurry drops to 30 °C, transfer it to the centrifugal device to separate the accelerator product from the mother liquor; (4) After subjecting the accelerator product to high-temperature vacuum evaporation to dryness and pulverization treatment, obtain the finished accelerator ZDMC; (5) Calculate the recovery rates of the finished accelerators obtained in Example 3 and Comparative Example 1 respectively; Use the stripping deammoniation technology to quantitatively remove COD and ammonia nitrogen from the mother liquor of the accelerator in Comparative Example 1. Detect the COD and ammonia nitrogen contents of the mother liquor before and after treatment in Example 3 and Comparative Example 1 respectively. The results are shown in the following table.

[0029] Project Example 3 Comparative Example 1 Product recovery rate ＞98% 91-93.5% Wastewater treatment capacity 3.5 t / h 3.5 t / h Wastewater index before treatment COD = 28000 - 35000 mg / L Ammonia nitrogen: 3000 - 4000 ppm COD = 28000 - 35000 mg / L Ammonia nitrogen: 3000 - 4000 ppm Wastewater index after treatment COD = 600 - 1000 mg / L Ammonia nitrogen: 100 - 500 ppm COD = 5000 - 15000 mg / L Ammonia nitrogen: 1000 - 1500 ppm Energy consumption <![CDATA[Only 1.7 - 3 kg equivalent of Zn per ton of wastewater 2+ (the actual weight is subject to the specific zinc salt) and 120 - 140 g of surfactant]]> Average steam consumption: 180 - 200 kg / t wastewater 。

[0030] The above content illustrates the technical idea and specific implementation of the present invention by way of examples. The protection scope of the present invention cannot be limited thereby. For those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements all fall within the protection scope of the claims of the present invention.

Claims

1. An improved method for producing a vulcanization accelerator, characterized in that: The following steps are involved: (1) For the accelerator reaction slurry after the reaction in the reactor, the obtained slurry is heated by a jacket device in the reactor and kept warm for a certain period of time to evaporate the unreacted carbon disulfide and leave the reaction slurry; (2) using a negative pressure draft cooling recovery device to collect the carbon disulfide evaporated in step (1) to obtain a reaction slurry from which carbon disulfide has been removed; (3) adding a certain amount of active agent to the reaction slurry of step (2) and stirring thoroughly until it is completely dissolved; (4) adding a certain amount of soluble zinc salt to the reaction slurry of step (3) in batches at a certain speed through a drop control device, and keeping the temperature for a certain time after reaching the titration endpoint; (5) Cooling the reaction slurry of step (4) with condensed water, and separating the reaction slurry with a centrifugal device to obtain a high recovery rate promoter product and a mother liquor with low COD and low ammonia nitrogen content.

2. An improved method for producing a vulcanization accelerator according to claim 1, characterized in that: The reaction slurry in step (1) is obtained as follows: add an appropriate amount of water to a reaction kettle, and add materials according to the molar ratio of organic amine, carbon disulfide, and zinc oxide of 1:1.0-1.3:0.45-0.6 for reaction, wherein the type of organic amine is any one of dimethylamine and diethylamine, and the reaction is completed at a certain temperature to obtain a promoter reaction slurry.

3. An improved method for producing a vulcanization accelerator according to claim 1, characterized in that: In step (1), the reactor is heated to 60-80° C., and the insulation time is 1-2 h.

4. An improved method for producing a vulcanization accelerator according to claim 1, characterized in that: In step (3), the type of the active agent is one or both of sodium dodecylbenzene sulfonate and Taiko oil.

5. An improved method for producing a vulcanization accelerator according to claim 1, characterized in that: In step (3), the concentration of the active agent in the reaction slurry is 0.1-0.15 g / L.

6. An improved method for producing a vulcanization accelerator according to claim 1, characterized in that: In step (4), the soluble zinc salt is one or more of zinc chloride, zinc nitrate and zinc acetate.

7. An improved method for producing a vulcanization accelerator according to claim 1, characterized in that: In step (4), the concentration of the soluble zinc salt in the reaction slurry is 1.6-3 g equivalent of Zn 2+ / L.

8. An improved method for producing a vulcanization accelerator according to claim 1, characterized in that: In step (4), the soluble zinc salt is added in 1-4 batches, and the time interval between each batch addition is 15-30 min.

9. An improved method for producing a vulcanization accelerator according to claim 1, characterized in that: In step (4), the soluble zinc salt is added at a rate of 100-500 g equivalent Zn 2+ / min.

10. An improved method for producing a vulcanization accelerator according to claim 1, characterized in that: In step (4), the pH of the titration endpoint is 5-7, and the insulation time is 0.5-1h.