阅读说明：本技术 一种用于废硫酸的回收方法 (Method for recovering waste sulfuric acid ) 是由 黄中桂 袁晓林 朱礼华 陈军 孔德明 于 2020-07-28 设计创作，主要内容包括：本发明涉及一种用于废硫酸的回收方法,基于一套回收装置,回收装置包括有过滤釜、萃取釜、精馏Ⅰ釜、精馏Ⅱ釜、阳离子交换树脂柱、浓缩釜和双重冷凝器；本发明的废硫酸的回收方法针对的是氯苯法制备对硝基酚的生产过程,先通过过滤的方式分离废硫酸中的不溶物,用苯萃取废硫酸中的剩余的有机物,并通过精馏的方式分离出萃取剂,再通过离子交换后浓缩得到较高纯度的硫酸溶液；本发明创造性地用萃取的方式将废硫酸中的有机相剥离废硫酸,再通过离子交换拦截溶液中的金属离子,将溶液中盐含量降至最低,实现溶液中杂质过滤,回收的废硫酸、有机相可重复套用,进而降低生产成本,提高经济效益,具有良好的实用性和应用前景。(The invention relates to a recovery method for waste sulfuric acid, which is based on a set of recovery device, wherein the recovery device comprises a filtering kettle, an extraction kettle, a rectification kettle I, a rectification kettle II, a cation exchange resin column, a concentration kettle and a double condenser; the method for recovering the waste sulfuric acid aims at the production process of preparing the p-nitrophenol by the chlorobenzene method, firstly, insoluble substances in the waste sulfuric acid are separated in a filtering mode, the residual organic substances in the waste sulfuric acid are extracted by benzene, an extracting agent is separated in a rectifying mode, and then, a sulfuric acid solution with higher purity is obtained by concentration after ion exchange; the invention creatively uses the extraction mode to strip the organic phase in the waste sulfuric acid from the waste sulfuric acid, then intercepts the metal ions in the solution through ion exchange, reduces the salt content in the solution to the minimum, realizes the filtration of impurities in the solution, and can repeatedly use the recovered waste sulfuric acid and the organic phase, thereby reducing the production cost, improving the economic benefit and having good practicability and application prospect.)

1. A method for recovering waste sulfuric acid is characterized in that: the recovery method is based on a set of recovery device, the recovery device comprises a filtering kettle (1), an extraction kettle (2), a rectifying I kettle (3), a rectifying II kettle (4), a cation exchange resin column (5) and a concentration kettle (6), and double condensers (7) are connected to the rectifying I kettle (3), the rectifying II kettle (4) and the concentration kettle (6);

the method for recovering the waste sulfuric acid comprises the following steps:

1) filtering: transferring the solution containing the waste sulfuric acid into a filtering kettle, heating to 50-80 ℃, adding coconut shell activated carbon into the solution, stirring at a stirring speed of 500-800 r/min for 20-40 min, standing at a constant temperature for 10-30 min, performing filter pressing with a microfiltration membrane, performing filter pressing with a nanofiltration membrane, controlling the air pressure to be 0.2-0.5 Mpa, and collecting filtrate;

2) extraction: transferring the filtrate into an extraction kettle, cooling to 20-30 ℃, adding an extractant benzene into the filtrate, uniformly stirring at a stirring speed of 500-800 r/min, standing for layering, transferring an organic phase into a rectification I kettle, and transferring a water phase into a rectification II kettle;

3) rectifying: setting different heating temperature points according to the boiling point difference of benzene and other organic matters in the rectifying kettle I, stirring at a stirring speed of 500-1000 r/min, completely separating an extracting agent from other organic components, directly using high-boiling-point impurities at the bottom of the rectifying kettle as fuel for combustion, and recovering the extracting agent benzene;

heating the temperature of a rectification II kettle to 80-100 ℃, stirring at a stirring speed of 500-1000 r/min, collecting rectified light components, heating to 100-110 ℃ again, rectifying to remove water, and primarily concentrating the solution;

4) column passing: transferring the heavy rectification component in the rectification II kettle into a cation exchange resin column for cation exchange, recovering a sulfuric acid solution from the lower end of the resin column, and controlling the temperature of the column passing at 20-50 ℃;

5) concentrating: transferring the sulfuric acid solution after column passing into a concentration kettle, raising the temperature in the kettle to 100-150 ℃, rectifying to remove water and concentrate sulfuric acid, and controlling the rectifying temperature and the rectifying time according to the required concentration to obtain the recovered waste sulfuric acid.

2. A recovery process for spent sulfuric acid according to claim 1, characterized in that: in the recovery method, the mass percent of the coconut shell activated carbon added into the filtering kettle in the step 1 is 5-15%.

3. A recovery process for spent sulfuric acid according to claim 1, characterized in that: in the recovery method, in the step 1, the membrane aperture of the microfiltration membrane is 500-800 nm, and the membrane aperture of the nanofiltration membrane is 50-250 nm.

4. A recovery process for spent sulfuric acid according to claim 1, characterized in that: in the recovery method, the mass percent of the extractant benzene added in the step 2 is 30-70%.

5. A recovery process for spent sulfuric acid according to claim 1, characterized in that: in the recovery method, the concentration of the primarily concentrated sulfuric acid solution in the rectifying II kettle in the step 3 is 30-50%.

6. A recovery process for spent sulfuric acid according to claim 1, characterized in that: the cation exchange resin in the step 4 of the recovery method is hydrogen ion exchange resin.

7. A recovery process for spent sulfuric acid according to claim 1, characterized in that: the concentration of the sulfuric acid solution finally recovered in the step 5 of the recovery method is 50-80%.

Technical Field

The invention relates to the technical field of waste acid recovery, in particular to a recovery method for waste sulfuric acid.

Background

Sulfuric acid has been widely used as a chemical product in various industries, such as chemical industry, petroleum industry, etc., and a large amount of dilute sulfuric acid is produced in the production process. In order to avoid pollution of dilute sulfuric acid to the environment, lime or other alkaline solutions are generally adopted for neutralization, but consumption of lime or other alkaline solutions is caused, and waste of sulfuric acid resources is caused, and concentration of waste sulfuric acid is beneficial to reducing consumption of substances such as lime and the like, recycling of sulfuric acid can be achieved, economic cost is increased, and a resource-saving society is constructed.

At present, the concentration treatment of dilute sulfuric acid in production mainly comprises the following methods: evaporating and eluting water at high temperature in a heating environment, or concentrating under reduced pressure in a heating process. However, since sulfuric acid has a strong corrosiveness, it is liable to corrode the concentration equipment, and the consumption rate of the concentration equipment is further increased under a high temperature condition, which will increase the maintenance and management costs of the concentration equipment. In addition, different industrial waste liquids contain dilute sulfuric acid to be recovered, and also contain other waste materials, for example, in the process of producing alkylate by a sulfuric acid method, isoparaffin and olefin generate alkylate under the catalysis of strong acid, and the reaction only contains waste sulfuric acid in the waste liquid, but also contains a small amount of unreacted isoparaffin, olefin and alkylate which is completely separated. The waste sulfuric acid solution from the pickling of the factory may also contain metal ions such as Fe 3+, Ni +, Cr 3+ and the like, and may also contain chlorine or other suspended matters. If the waste liquid is directly used for heating and concentrating, only the effect of concentrating sulfuric acid can be achieved, and the effect of increasing the purity of the sulfuric acid cannot be achieved.

In conclusion, the prior art has the problems that the equipment loss rate is high and the purity of the sulfuric acid cannot be improved in the process of heating and concentrating the sulfuric acid.

Disclosure of Invention

The invention aims to provide a method for recovering waste sulfuric acid, which aims to recover a high-purity and high-concentration sulfuric acid solution from the waste sulfuric acid, degrade the loss rate, improve the economic benefit and avoid environmental pollution.

The invention is realized by the following technical scheme:

a recovery method for waste sulfuric acid is based on a set of recovery device, the recovery device comprises a filtering kettle (1), an extraction kettle (2), a rectifying kettle I (3), a rectifying kettle II (4), a cation exchange resin column (5) and a concentration kettle (6), and double condensers (7) are connected to the rectifying kettle I (3), the rectifying kettle II (4) and the concentration kettle (6);

the method for recovering the waste sulfuric acid comprises the following steps:

1) filtering: transferring the solution containing the waste sulfuric acid into a filtering kettle, heating to 50-80 ℃, adding coconut shell activated carbon into the solution, stirring at a stirring speed of 500-800 r/min for 20-40 min, standing at a constant temperature for 10-30 min, performing filter pressing with a microfiltration membrane, performing filter pressing with a nanofiltration membrane, controlling the air pressure to be 0.2-0.5 Mpa, and collecting filtrate;

2) extraction: transferring the filtrate into an extraction kettle, cooling to 20-30 ℃, adding an extractant benzene into the filtrate, uniformly stirring at a stirring speed of 500-800 r/min, standing for layering, transferring an organic phase into a rectification I kettle, and transferring a water phase into a rectification II kettle;

3) rectifying: setting different heating temperature points according to the boiling point difference of benzene and other organic matters in the rectifying kettle I, stirring at a stirring speed of 500-1000 r/min, completely separating an extracting agent from other organic components, directly using high-boiling-point impurities at the bottom of the rectifying kettle as fuel for combustion, and recovering the extracting agent benzene;

heating the temperature of a rectification II kettle to 80-100 ℃, stirring at a stirring speed of 500-1000 r/min, collecting rectified light components, heating to 100-110 ℃ again, rectifying to remove water, and primarily concentrating the solution;

4) column passing: transferring the heavy rectification component in the rectification II kettle into a cation exchange resin column for cation exchange, recovering a sulfuric acid solution from the lower end of the resin column, and controlling the temperature of the column passing at 20-50 ℃;

5) concentrating: transferring the sulfuric acid solution after column passing into a concentration kettle, raising the temperature in the kettle to 100-150 ℃, rectifying to remove water and concentrate sulfuric acid, and controlling the rectifying temperature and the rectifying time according to the required concentration to obtain the recovered waste sulfuric acid.

As a preferable technical scheme, the mass percent of the coconut shell activated carbon added into the filtering kettle in the step 1 of the recovery method is 5-15%.

As a preferable technical scheme, in the recovery method, in the step 1, the membrane aperture of the microfiltration membrane is 500-800 nm, and the membrane aperture of the nanofiltration membrane is 50-250 nm.

As a preferable technical scheme, the mass percent of the extractant benzene added in the step 2 of the recovery method is 30-70%.

As a preferable technical scheme, the concentration of the primarily concentrated sulfuric acid solution in the rectifying II kettle in the step 3 of the recovery method is 30-50%.

Preferably, the cation exchange resin in step 4 of the recovery method is a hydrogen ion exchange resin.

Preferably, the concentration of the sulfuric acid solution finally recovered in step 5 of the recovery method is 50-80%.

The invention has the beneficial effects that: the method for recovering the waste sulfuric acid aims at the production process of preparing the p-nitrophenol by the chlorobenzene method, firstly, insoluble substances in the waste sulfuric acid are separated in a filtering mode, the residual organic substances in the waste sulfuric acid are extracted by benzene, an extracting agent is separated in a rectifying mode, and then, a sulfuric acid solution with higher purity is obtained by concentration after ion exchange; the invention creatively uses the extraction mode to strip the organic phase in the waste sulfuric acid from the waste sulfuric acid, then intercepts the metal ions in the solution through ion exchange, reduces the salt content in the solution to the minimum, realizes the filtration of impurities in the solution, and can repeatedly use the recovered waste sulfuric acid and the organic phase, thereby reducing the production cost, improving the economic benefit and having good practicability and application prospect.

Drawings

FIG. 1 is a schematic view of the overall structure of a recovery apparatus for waste sulfuric acid according to the present invention.

In the figure: 1. filtering the kettle; 2. an extraction kettle; 3. a rectifying kettle I; 4. a rectifying kettle II; 5. a cation exchange resin column; 6. a concentration kettle; 7. a double condenser.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious 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.