Waste acid treatment system and method based on vacuum degassing

Abstract

The invention discloses a waste acid treatment system and method based on vacuum degassing, the waste acid treatment system comprises a waste acid input unit, a dosing unit, a negative pressure former, a mixing device, a reaction tank and a vacuum tower, the waste acid input unit is communicated with a liquid phase inlet of the negative pressure former, and a top outlet of the vacuum tower is communicated with a gas phase inlet of the negative pressure former; an outlet of the negative pressure former is communicated with a first inlet of the mixing device, an outlet of the dosing unit is communicated with a second inlet of the mixing device, an outlet of the mixing device is communicated with a feed port of the reaction tank, and a discharge port of the reaction tank is communicated with a feed port of the vacuum tower. According to the waste acid treatment system and method, the kinetic energy of a waste acid input source is utilized, negative pressure is generated according to the negative pressure former principle, liquid obtained after vulcanization reaction is desorbed, chemicals are fully recycled, the utilization rate is increased, meanwhile, residual vulcanization chemicals in the liquid obtained after vulcanization reaction are avoided, and safety guarantee is provided for further treatment of waste acid in a downstream workshop section.

Description

Technical Field

[0001] The present invention belongs to the technical field of smelting acid wastewater treatment, and relates to a waste acid treatment system and method based on vacuum degassing, and specifically relates to a heavy metal-containing waste acid treatment system and method based on vacuum degassing. Background Art

[0002] Nonferrous metals such as copper, lead, and zinc in the smelting industry are all associated minerals containing S elements. A large amount of flue gas containing SO2 is produced during the pyrometallurgical smelting process. When the flue gas is washed and purified, a large amount of acidic wastewater containing heavy metal ions such as copper, arsenic, lead, zinc, and cadmium will be produced. This acidic wastewater contains toxic gases with pungent odors, and has the characteristics of multiple elemental components, high acidity, and strong corrosiveness. It is often treated in steps by "sulfurization + lime neutralization method". The reagent utilization rate in the sulfidation treatment process is only 70%-85%, which has the disadvantages of low reagent utilization rate, poor reaction effect, toxic gas leakage, and high energy consumption. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a waste acid treatment system and method based on vacuum degassing with high reagent utilization rate, extremely low residual reagent amount in the liquid after degassing, low safety risk, low energy consumption and short process.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0005] A waste acid treatment system based on vacuum degassing, comprising a waste acid input unit, a dosing unit, a negative pressure generator, a mixing device, a reaction tank and a vacuum tower, wherein the negative pressure generator is provided with a gas phase inlet and a liquid phase inlet, the waste acid input unit is communicated with the liquid phase inlet of the negative pressure generator, the top outlet of the vacuum tower is communicated with the gas phase inlet of the negative pressure generator, the mixing device is provided with a first inlet and a second inlet, the outlet of the negative pressure generator is communicated with the first inlet of the mixing device, the outlet of the dosing unit is communicated with the second inlet of the mixing device, the outlet of the mixing device is communicated with the feed inlet of the reaction tank, and the discharge port of the reaction tank is communicated with the feed inlet of the vacuum tower.

[0006] The above-mentioned waste acid treatment system based on vacuum degassing is preferably provided with a negative pressure valve group between the top outlet of the vacuum tower and the gas phase inlet of the negative pressure former, and a vacuum tower negative pressure gauge is provided on the top of the vacuum tower; a first-level liquid distributor is provided below the feed inlet of the vacuum tower, and a second-level liquid distributor is provided below the first-level liquid distributor.

[0007] In the above-mentioned waste acid treatment system based on vacuum degassing, preferably, the waste acid input unit is connected to the liquid phase inlet of the negative pressure former through a waste acid delivery pipeline, a waste acid component detector is provided on the waste acid delivery pipeline, the waste acid component detector is connected to a dosing controller, and is used to feed back the concentration of the detected waste acid component to the dosing controller, a reaction tank pressure gauge is provided on the top of the reaction tank, the reaction tank pressure gauge is connected to the dosing controller, and is used to feed back the pressure detected by the reaction tank pressure gauge to the dosing controller, the outlet of the dosing unit is connected to the second inlet of the mixing device through a drug delivery pipeline, a drug delivery pipeline is provided with a drug regulating valve, and the dosing controller is connected to the drug regulating valve to control the opening of the drug regulating valve.

[0008] In the above-mentioned waste acid treatment system based on vacuum degassing, preferably, the mixing device includes a first mixer, a second mixer and a third mixer, the first mixer is provided with a first inlet and a second inlet, the second mixer is provided with a first inlet and a second inlet, the third mixer is provided with a first inlet and a second inlet, the first inlet of the first mixer, the first inlet of the second mixer, and the first inlet of the third mixer are respectively connected to the outlet of the negative pressure former, the second inlet of the first mixer, the second inlet of the second mixer, and the second inlet of the third mixer are respectively connected to the outlet of the pharmaceutical delivery pipeline, the reaction tank is provided with three feed ports, namely the first feed port, the second feed port and the third feed port, the first feed port is connected to the outlet of the first mixer, the second feed port is connected to the outlet of the second mixer, and the third feed port is connected to the outlet of the third mixer, the first feed port, the second feed port and the third feed port of the reaction tank are all provided with oblique feed pipes, and the angle of the oblique feed pipe to the side wall of the reaction tank is 30° to 60° upward.

[0009] The above-mentioned waste acid treatment system based on vacuum degassing is preferably provided with a waste acid regulating valve, a waste acid flowmeter and a waste acid pressure gauge on the waste acid delivery pipeline; the waste acid flowmeter is connected to the waste acid regulating valve to feed back the waste acid flow detected by the waste acid flowmeter to the waste acid regulating valve; and a reagent flowmeter is provided on the reagent delivery pipeline.

[0010] The above-mentioned waste acid treatment system based on vacuum degassing is preferably provided with an agitator and a discharge pipe, the agitator is connected to a reaction tank motor, and the discharge pipe is connected to the feed port of the vacuum tower; the kettle of the vacuum tower is provided with an inclined bottom, the slope of the inclined bottom is 10° to 20°, a drainage pump is provided at the bottom of the slope of the inclined bottom, and a defoamer is provided at the top of the vacuum tower.

[0011] In the above-mentioned waste acid treatment system based on vacuum degassing, preferably, the negative pressure former is a venturi ejector or a water-flushed vacuum pump, the waste acid component detector is an arsenic concentration online detection instrument, the first mixer, the second mixer, and the third mixer are blade mixers or spiral mixers, the reaction tank is made of acid-corrosion-resistant materials, and the acid-corrosion-resistant materials include one or more of titanium, fiberglass, rubber lining and fluorine lining, the pressure reducing tower is an empty tower or a packed tower, and the demister is a wire mesh demister or a baffle demister.

[0012] As a general technical concept, the present invention also provides a method for treating waste acid based on vacuum degassing, which is implemented using the above-mentioned waste acid treatment system based on vacuum degassing, and includes the following steps:

[0013] The waste acid is sent to the mixing device through the waste acid input unit and the negative pressure forming device, and the waste acid is arsenic-containing waste acid. The sulfiding agent is sent to the mixing device through the dosing unit, and the waste acid and the sulfiding agent are mixed in the mixing device. The obtained mixed liquid is sent to the reaction tank for sulfidation reaction. The reaction tank is controlled under a micro-positive pressure condition of 400Pa to 600Pa. After the reaction, the obtained sulfidation reaction liquid is sent to the vacuum tower, and the vacuum tower is controlled under a vacuum condition of 6kPa to 50kPa by the negative pressure forming device, so that the sulfiding agent in the sulfidation reaction liquid is resolved to achieve vacuum degassing. The sulfiding agent obtained after the resolution is returned to the negative pressure forming device, mixed with the waste acid from the waste acid input unit, and then sent to the reaction tank through the mixing device for continuous reaction. The degassed liquid obtained after the resolution is discharged from the vacuum tower, and finally the waste acid is treated.

[0014] In the above-mentioned waste acid treatment method based on vacuum degassing, preferably, the sulfiding agent includes one or more of sodium sulfide, sodium hydrosulfide and hydrogen sulfide gas; and / or the concentration of arsenic ions in the arsenic-containing waste acid is 4000 mg / L to 12000 mg / L.

[0015] In the above-mentioned waste acid treatment method based on vacuum degassing, preferably, the material flow rate sent to the mixing device is controlled at 1.0m / s to 2.0m / s, the material residence time in the reaction tank is controlled at 10min to 30min, and the liquid spray density of the liquid after the sulfidation reaction in the vacuum tower is controlled to be 10m 3 / (m 2 ·h)~30m 3 / (m 2 h).

[0016] In the present invention, the waste acid input unit generally includes a waste acid storage tank, a waste acid pump, a matching liquid level meter and a connecting pipeline.

[0017] In the present invention, the dosing unit generally includes a medicine preparation tank, a medicine storage tank, a pump, a matching liquid level meter and a connecting pipeline.

[0018] In the prior art, waste acid generated in the smelting industry usually contains As. The present invention mainly treats waste acid with high arsenic content.

[0019] In the present invention, after the sulfiding agent (taking sodium sulfide as an example) is mixed with the waste acid, the following chemical reaction will occur:

[0020] Na2S+2H + →H2S+2Na + (1)

[0021] H2S→2H + +S 2- (2)

[0022] S 2- +As 3+ →As2S3(precipitation) (3).

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] 1. The waste acid treatment system of the present invention is connected to the upstream waste acid through the waste acid input unit to provide a waste acid source. The waste acid passes through the negative pressure forming device and the mixing device in turn and enters the reaction tank (i.e., the downstream reaction unit). The system is connected to the upstream vulcanizing agent through the dosing unit to provide an agent source. The agent enters the reaction tank after the mixing device. The liquid after the vulcanization reaction obtained by the reaction is sent to the vacuum tower (i.e., the gas recovery unit). The top of the vacuum tower is connected to the negative pressure forming device to form a negative pressure in the vacuum tower. The waste acid is sprayed in the vacuum tower. The residual vulcanizing agent in the waste acid is analyzed under negative pressure conditions to achieve the purpose of vacuum degassing. The vulcanizing agent obtained by analysis is continuously recycled. The system makes full use of the power energy of the waste acid input unit, cancels the degassing fan, and reduces the use of the delivery pump in the system by negative pressure liquid introduction, reduces equipment investment, reduces installed power, and achieves the purpose of energy saving. The system uses the principle of the negative pressure forming device to produce a high vacuum to remove the residual vulcanizing agent in the liquid after the vulcanization reaction, so that the downstream section further processes the waste acid to achieve the purpose of safety and controllability.

[0025] 2. The waste acid treatment method of the present invention is a safe and energy-saving method for treating waste acid containing heavy metals. The method can utilize the kinetic energy of the waste acid source (such as the waste acid input unit with its own pump, without the need for additional devices such as fans), and utilize the principle of a negative pressure generator to generate negative pressure, desorb the liquid after the sulfidation reaction, fully recover the reagent, improve the utilization rate, and avoid residual sulfiding reagents in the liquid after the sulfidation reaction, so as to provide safety for further treatment of waste acid in the downstream section. The method of the present invention controls the reaction under micro-positive pressure conditions, thereby controlling the reagent to be in a micro-excess state. The intermediate product of the reaction between the waste acid and the sulfiding reagent contains hydrogen sulfide. The pressure of the micro-positive pressure mainly comes from hydrogen sulfide. By controlling the micro-positive pressure, the reagent can be controlled to be in a micro-excess state. The utilization rate of the sulfiding reagent of the waste acid treatment method of the present invention can reach more than 99.5%, and the amount of residual sulfiding reagents in the degassed liquid is ≤50ppm.

[0026] In summary, the present invention aims at the technical problems of the prior art and proposes a treatment system and method for heavy metal-containing waste acid with vacuum degassing, low safety risk, avoidance of toxic gas leakage and low energy consumption. The system and method of the present invention combine the sulfidation method and the unpowered gas recovery design, which increases the utilization efficiency of the reagents and reduces the power consumption of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic structural diagram of a waste acid treatment system based on vacuum degassing according to Example 1 of the present invention.

[0028] Legend:

[0029] 1. Dosing unit; 2. Dosing controller; 3. Waste acid regulating valve; 4. Waste acid input unit; 5. Negative pressure former; 6. Reactor; 7. Pressure reducing tower; 8. Pressure reducing tower negative pressure gauge; 9. Negative pressure valve group; 10. Chemical conveying pipeline; 11. Chemical flow meter; 12. Chemical regulating valve; 13. Reactor pressure gauge; 14. Waste acid component detector; 15. Reactor motor; 16. Waste acid conveying pipeline; 17. Waste acid flow meter; 18. Vacuum pipe; 19. Oblique feed pipe; 20. Discharge pipe; 21. Agitator; 22. Primary liquid distributor; 23. Secondary liquid distributor; 24. Tower kettle; 25. Liquid discharge pump; 26. Defoamer; 27. Oblique bottom; 28. Waste acid pressure gauge; 29. ​​First mixer; 30. Second mixer; 31. Third mixer. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby. The materials and instruments used in the following embodiments are all commercially available.

[0031] Example 1

[0032] A waste acid treatment system based on vacuum degassing of the present invention, such as Figure 1 As shown, it includes a waste acid input unit 4, a dosing unit 1, a negative pressure generator 5, a mixing device, a reaction tank 6 and a vacuum tower 7. The negative pressure generator 5 is provided with a gas phase inlet and a liquid phase inlet. The waste acid input unit 4 is communicated with the liquid phase inlet of the negative pressure generator 5. The top outlet of the vacuum tower 7 is communicated with the gas phase inlet of the negative pressure generator 5. The mixing device is provided with a first inlet and a second inlet. The outlet of the negative pressure generator 5 is communicated with the first inlet of the mixing device. The outlet of the dosing unit 1 is communicated with the second inlet of the mixing device. The outlet of the mixing device is communicated with the feed port of the reaction tank 6. The discharge port of the reaction tank 6 is communicated with the feed port of the vacuum tower 7.

[0033] The waste acid treatment system of this embodiment is connected with the upstream waste acid through the waste acid input unit 4 to provide the waste acid source. The waste acid passes through the negative pressure forming device 5 and the mixing device in turn and enters the reaction tank 6 (i.e., the downstream reaction unit). The dosing unit 1 is connected with the upstream sulfiding agent to provide the agent source. The agent enters the reaction tank 6 after the mixing device. The sulfiding reaction liquid obtained by the reaction is sent to the vacuum tower 7 (i.e., the gas recovery unit). The top of the vacuum tower 7 is connected to the negative pressure forming device 5 to form a negative pressure in the vacuum tower 7. The waste acid is sprayed in the vacuum tower 7. The residual sulfiding agent in the waste acid is analyzed under negative pressure conditions to achieve the purpose of vacuum degassing. The sulfiding agent obtained by analysis is further recycled. The system makes full use of the power energy of the waste acid input unit, cancels the degassing fan, and reduces the use of the delivery pump in the system by negative pressure liquid introduction, reduces equipment investment, reduces installed power, and achieves the purpose of energy saving. The system uses the principle of a negative pressure generator to generate a high vacuum to remove the residual sulfiding agent in the liquid after the sulfidation reaction, so that the downstream process can further treat the waste acid in a safe and controllable manner.

[0034] In this embodiment, a negative pressure valve group 9 is provided between the top outlet of the vacuum tower 7 and the gas phase inlet of the negative pressure generator 5, and a vacuum tower negative pressure gauge 8 is provided at the top of the vacuum tower 7. During normal operation, negative pressure is formed at the top of the vacuum tower 7 through the negative pressure generator 5, and the opening of the negative pressure valve group 9 is controlled by the vacuum tower negative pressure gauge 8 to adjust the negative pressure value. A first-level liquid distributor 22 is provided below the feed inlet of the vacuum tower 7, and a second-level liquid distributor 23 is provided below the first-level liquid distributor 22.

[0035] In this embodiment, the waste acid input unit 4 is connected to the liquid phase inlet of the negative pressure generator 5 through a waste acid delivery pipeline 16. The waste acid delivery pipeline 16 is provided with a waste acid component detector 14 for detecting the As concentration in the waste acid. The waste acid component detector 14 is connected to a dosing controller 2 (signal connection can be adopted). The waste acid component detector 14 of this embodiment adopts an online detection instrument, which is used to automatically detect the As concentration in the waste acid and feed back the signal to the dosing controller 2. A reaction tank pressure gauge 13 is provided on the top of the reaction tank 6. The reaction tank pressure gauge 13 is connected to the dosing controller 2 (signal connection can be adopted), and the pressure signal detected by the reaction tank pressure gauge 13 is fed back to the dosing controller 2. The reaction tank 6 is usually controlled under a micro-positive pressure condition of 400Pa to 600Pa, so that when the waste acid and the sulfiding agent react, the sulfiding agent is always in a micro-excess state. The outlet of the dosing unit 1 is connected to the second inlet of the mixing device through the drug delivery pipeline 10. The drug delivery pipeline 10 is provided with a drug regulating valve 12. The dosing controller 2 is connected to the drug regulating valve 12. The opening of the drug regulating valve 12 is interlocked by the dosing controller 2. The dosing controller 2 controls the opening of the drug regulating valve 12 according to the feedback signals from the waste acid component detector 14 and the reaction tank pressure gauge 13, thereby controlling the amount of drug added.

[0036] In this embodiment, the mixing device includes a first mixer 29, a second mixer 30 and a third mixer 31. The first mixer 29 is provided with a first inlet and a second inlet, the second mixer 30 is provided with a first inlet and a second inlet, and the third mixer 31 is provided with a first inlet and a second inlet. The first inlet of the first mixer 29, the first inlet of the second mixer 30, and the first inlet of the third mixer 31 are respectively connected to the outlet of the negative pressure forming device 5, and the second inlet of the first mixer 29, the second inlet of the second mixer 30, and the second inlet of the third mixer 31 are respectively connected to the outlet of the drug delivery pipeline 10. The reaction tank 6 is provided with three feed ports, namely, the first feed port and the second inlet. The first feed port is connected to the outlet of the first mixer 29, the second feed port is connected to the outlet of the second mixer 30, and the third feed port is connected to the outlet of the third mixer 31. The first feed port, the second feed port and the third feed port of the reaction tank 6 are all provided with an inclined feed pipe 19, and the angle between the inclined feed pipe 19 and the side wall of the reaction tank 6 is 30° to 60° upward. The present embodiment specifically adopts 3 inclined feed pipes, and the feeding position is at the same height as the paddle of the agitator 21. The angle between the inclined feed pipe and the side wall is 30° upward. The inclined feed pipe 19 makes the material upward and flows upward after the liquid is taken in, thereby increasing the residence time and avoiding direct discharge from the discharge pipe 20 after the liquid is taken in.

[0037] In this embodiment, a waste acid regulating valve 3, a waste acid flowmeter 17 and a waste acid pressure gauge 28 are provided on the waste acid transport pipeline 16. The waste acid flowmeter 17 is connected to the waste acid regulating valve 3 (signal connection can be adopted) to feed back the waste acid flow signal detected by the waste acid flowmeter 17 to the waste acid regulating valve 3.

[0038] In this embodiment, a medicine flow meter 11 is provided on the medicine delivery pipeline 10 .

[0039] In this embodiment, the reaction tank 6 is provided with a stirrer 21 and a discharge pipe 20 . The stirrer 21 is connected to a reaction tank motor 15 , and the discharge pipe 20 is communicated with a feed port of the vacuum tower 7 .

[0040] In this embodiment, the kettle 24 of the vacuum tower 7 is provided with a sloping bottom 27, the slope of the sloping bottom 27 can be selected from 10° to 20°, specifically 15° in this embodiment, a drainage pump 25 is provided at the bottom of the slope of the sloping bottom 27, and a defoamer 26 is provided at the top of the vacuum tower 7.

[0041] In the present embodiment, the negative pressure forming device 5 is a Venturi ejector RPP-65, PP material, and the negative pressure forming device 5 can be a Venturi ejector or a water-flushing vacuum pump. The first mixer 29, the second mixer 30, and the third mixer 31 are blade mixers or spiral mixers, and the blade mixer has a conical nozzle inside, and the spiral mixer has a spiral blade inside, which can increase the mixing effect of waste acid and reagents, and the material flow rate is controlled at 1.0m / s-2.0m / s, and the effect is better. The present embodiment adopts a blade mixer. The reaction tank 6 is composed of an acid-corrosion-resistant material, and the acid-corrosion-resistant material includes one or more of titanium, glass fiber reinforced plastic, rubber lining and fluorine lining. The present embodiment adopts carbon steel rubber lining. The vacuum tower 7 can be an empty tower or a packed tower, and the demister 26 can be a wire mesh demister or a baffle demister. In view of the anti-blocking measures, the vacuum tower 7 adopts an empty tower structure, the first-level liquid distributor 22 is a trough liquid distributor, and the second-level liquid distributor 23 is a swirl plate liquid distributor. The vacuum tower 7 is made of glass fiber reinforced plastic anti-corrosion material and can withstand high vacuum. The pressure of the vacuum tower negative pressure gauge 8 can be set to 6kPa~50kPa. The vacuum tower negative pressure gauge 8 detects that the pressure is reduced and closes the negative pressure valve group 9, and opens the negative pressure valve group 9 when the pressure increases. When the equipment is arranged, the bottom of the vacuum tower 7 is 2 meters higher than the drainage pump 25 to offset the effect of the negative pressure in the vacuum tower 7 on the drainage. The residual sulfidizing agent content of the degassed liquid obtained after desorption in the vacuum tower 7 is ≤50ppm.

[0042] A method for treating waste acid based on vacuum degassing of the present invention is implemented using the waste acid treatment system based on vacuum degassing of this embodiment, comprising the following steps:

[0043] The waste acid is sent to the mixer through the waste acid input unit 4 and the negative pressure forming device 5, and the vulcanizing agent is sent to the mixing device through the dosing unit 1. The waste acid and the vulcanizing agent are mixed in the mixing device to obtain a mixed liquid, and the mixed liquid is sent to the reaction tank 6 for vulcanization reaction. The reaction tank 6 is controlled under a micro-positive pressure condition of 400Pa-600Pa, so that when the waste acid and the vulcanizing agent react, the vulcanizing agent is always in a micro-excess state. After the reaction, the obtained vulcanization reaction liquid is sent to the vacuum tower 7, and the vacuum tower 7 is controlled under a vacuum condition of 6kPa-50kPa (controlled at 20kPa in this embodiment) by the negative pressure forming device 5, so that the vulcanizing agent in the vulcanization reaction liquid is resolved to realize vacuum degassing, and the vulcanizing agent obtained after the resolution is returned to the negative pressure forming device 5, mixed with the waste acid from the waste acid input unit 4, and then sent to the reaction tank 6 through the mixer to continue the reaction, and the degassed liquid obtained after the resolution is discharged from the vacuum tower 7, and finally the waste acid is treated.

[0044] In the present embodiment, the waste acid is acidic wastewater containing heavy metal ions such as As, mainly containing the following components and contents: H2SO4 is 70g / L, As is 12000mg / L, Cu is 50mg / L, Pb is 20mg / L, Cd is 100mg / L, Zn is 380mg / L, F is 3000mg / L, and Cl is 2000mg / L. When processing multiple batches of waste acid in general, the components and contents of the waste acid can fluctuate in the following ranges: H2SO4 is 50-100g / L, As is 4000-12000mg / L, Cu is 20-400mg / L, Pb is 5-120mg / L, Cd is 30-200mg / L, Zn is 160-450mg / L, F is 1500-4500mg / L, and Cl is 1000-3000mg / L. Among them, As, Cu, Pb, and Cd can react with the sulfiding agent to produce response precipitation, while other ions do not react with the sulfiding agent under acidic conditions. The As concentration in the waste acid is much greater than the concentration of other reactive metal ions, so the agent consumption is mainly related to the As ion concentration. The treatment capacity of acidic wastewater is 80m 3 / h, and the maximum head of the feed pump configured for the waste acid input unit 4 is 32m.

[0045] In this embodiment, the sulfiding agent is hydrogen sulfide gas, and sodium sulfide or sodium hydrosulfide may also be used.

[0046] In this embodiment, the maximum suction volume of the negative pressure generator 5 is 150m 3 / h, generating a negative pressure of -20 kPa to ensure the desorption effect, and the waste acid is ejected from the negative pressure generator 5 along with the gas from the vacuum tower 7.

[0047] In this embodiment, the material flow rate sent to the mixer is controlled at 1.5 m / s, the material residence time in the reaction tank 6 is controlled at 15 min, the liquid after the vulcanization reaction in the vacuum tower 7 enters the first-level liquid distributor 22 to form dispersed droplets, and then the droplets are spirally dropped through the second-level liquid distributor 23. The liquid spray density of the liquid after the vulcanization reaction is controlled at 15 m 3 / (m 2 h), the residual vulcanizing agent in the droplets is resolved under negative pressure to achieve the purpose of vacuum degassing.

[0048] In this embodiment, the As ion concentration in the waste acid influent is 12000 mg / L. Under the condition of fluctuating influent water quality, the As ion concentration in the liquid after the sulfidation reaction can be stabilized at less than 1 mg / L for a long time, and the removal rate can be stably reached above 99.5%. The residual sulfidation agent content in the degassed liquid after desorption in the vacuum tower 7 is ≤50ppm, and the comprehensive utilization rate of the agent can reach above 99.5%. The waste acid treatment system and method of the present invention have the characteristics of good reaction effect, stable water outlet, high agent utilization rate, and low residual agent content in the degassed liquid.

[0049] The working principle of the waste acid treatment and method based on vacuum degassing in this embodiment is as follows:

[0050] Acidic wastewater containing heavy metal ions (Cu, As, etc.) (referred to as waste acid, usually upstream waste acid) is sent to the waste acid input unit 4, and then sent to the negative pressure generator 5 through the waste acid delivery pipeline 16. The waste acid flowmeter 17 on the waste acid delivery pipeline 16 is used to detect the flow of the waste acid and feed it back to the waste acid regulating valve 3. The flow of the waste acid is adjusted by the waste acid regulating valve 3 to ensure a continuous and stable supply of waste acid. The waste acid pressure gauge 28 on the waste acid delivery pipeline 16 is used to detect the pressure of the waste acid. The waste acid component detector 14 arranged on the waste acid delivery pipeline 16 adopts an arsenic concentration online detector (commercially available) to automatically detect the concentration of As in the waste acid and feed the signal back to the dosing controller 2. The vulcanizing agent (usually the upstream vulcanizing agent) is delivered to the dosing unit 1, and is respectively delivered to the first mixer 29, the second mixer 30 and the third mixer 31 through the agent input pipeline 10. The agent flow meter 11 on the agent input pipeline 10 is used to monitor the flow of the agent. The opening of the agent regulating valve 12 is interlocked with the dosing controller 2. The dosing controller 2 controls the opening of the agent regulating valve 12 according to the feedback signals from the waste acid component detector 14 and the reaction tank pressure gauge 13, thereby controlling the amount of agent added (controlling the micro positive pressure). The negative pressure former 5 is provided with a liquid phase inlet and a gas phase inlet, the outlet of the waste acid conveying pipeline 16 is communicated with the liquid phase inlet of the negative pressure former 5, the top outlet of the vacuum tower 7 is communicated with the gas phase inlet of the negative pressure former 5, and the waste acid entrained gas passes through the outlet of the negative pressure former 5 and is evenly divided into three streams of materials, which are respectively conveyed to the first mixer 29, the second mixer 30, and the third mixer 31 to mix with the vulcanizing agent (certain reactions will occur) to form a first mixed liquid, a second mixed liquid, and a third mixed liquid, respectively. The first mixed liquid, the second mixed liquid, and the third mixed liquid are respectively conveyed to the reaction tank 6 through three oblique feed pipes 19 for vulcanization reaction, and are stirred by the agitator 21 during the reaction process. The liquid after the vulcanization reaction is conveyed to the feed port of the vacuum tower 7 through the discharge pipe 20, and the top outlet of the vacuum tower 7 is communicated with the gas phase inlet of the negative pressure former 5 through the exhaust pipe 18. Through the action of the negative pressure former 5, the vacuum tower 7 forms a negative pressure. When the reading of the negative pressure gauge 8 is higher than the set value, the valve opening of the negative pressure valve group 9 is automatically closed, and when the reading of the negative pressure gauge 8 is lower than the set value, the valve opening of the negative pressure valve group 9 is automatically opened, so as to maintain the negative pressure value of the vacuum tower 7 within the set range. A first-level liquid distributor 22 is provided below the feed port of the vacuum tower 7, and a second-level liquid distributor 23 is provided below the first-level liquid distributor 22. The liquid after the sulfidation reaction forms dispersed droplets through the first-level liquid distributor 22, and then the droplets are spirally descended after passing through the second-level liquid distributor 23. The residual sulfiding agent in the droplets is analyzed under negative pressure conditions to achieve the purpose of vacuum degassing. A defoamer 26 is provided at the top of the vacuum tower 7. The tower kettle 24 of the vacuum tower 7 adopts an inclined bottom 27, and the degassed liquid after desorption of the vacuum tower 7 passes through the inclined bottom 27 and the sloped drainage pump 25 to the downstream for treatment.

[0051] Comparative Example 1

[0052] A method for treating waste acid based on vacuum degassing is basically the same as Example 1, except that: the reaction tank pressure gauge 13 controls the micro-positive pressure to 0-50Pa, the vacuum tower negative pressure gauge 8 controls the negative pressure value to -0.1kPa~0kPa, the content of the residual sulfiding agent in the desorbed and degassed liquid after the vacuum tower 7 is about 400ppm, the utilization rate of the sulfiding agent is about 85%, and the removal rate of As ions in the waste acid is 97.5%.

[0053] Comparative Example 2

[0054] A method for treating waste acid based on vacuum degassing is basically the same as Example 1, except that: the reaction tank pressure gauge 13 controls the micro-positive pressure to be 100-300Pa, the vacuum tower negative pressure gauge 8 controls the negative pressure value to be -10kPa, the content of the residual sulfiding agent in the desorbed and degassed liquid after the vacuum tower 7 is about 100ppm, the utilization rate of the sulfiding agent is 96%, and the removal rate of As ions in the waste acid is 98.5%.

[0055] Comparative Example 3

[0056] A method for treating waste acid based on vacuum degassing is basically the same as Example 1, except that: there is no vacuum tower 7, the reaction tank pressure gauge 13 controls the micro-positive pressure to be 400-600Pa, and the removal rate of As ions in the waste acid can still reach more than 99.5%, but the content of the residual sulfiding agent in the sulfided liquid discharged from the discharge pipe 20 is about 700ppm, and the utilization rate of the sulfiding agent does not exceed 75%.

[0057] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as above in the preferred embodiment, it is not used to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention, still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A waste acid treatment system based on vacuum degassing, characterized in that: The invention comprises a waste acid input unit (4), a dosing unit (1), a negative pressure generator (5), a mixing device, a reaction tank (6) and a vacuum tower (7), wherein the negative pressure generator (5) is provided with a gas phase inlet and a liquid phase inlet, the waste acid input unit (4) is communicated with the liquid phase inlet of the negative pressure generator (5), the top outlet of the vacuum tower (7) is communicated with the gas phase inlet of the negative pressure generator (5), the mixing device is provided with a first inlet and a second inlet, the outlet of the negative pressure generator (5) is communicated with the first inlet of the mixing device, the outlet of the dosing unit (1) is communicated with the second inlet of the mixing device, the outlet of the mixing device is communicated with the feed inlet of the reaction tank (6), and the discharge outlet of the reaction tank (6) is communicated with the feed inlet of the vacuum tower (7).

2. The waste acid treatment system based on vacuum degassing according to claim 1, characterized in that: A negative pressure valve group (9) is provided between the top outlet of the vacuum tower (7) and the gas phase inlet of the negative pressure generator (5), and a vacuum tower negative pressure gauge (8) is provided at the top of the vacuum tower (7); a first-level liquid distributor (22) is provided below the feed inlet of the vacuum tower (7), and a second-level liquid distributor (23) is provided below the first-level liquid distributor (22).

3. The waste acid treatment system based on vacuum degassing according to claim 1 or 2, characterized in that: The waste acid input unit (4) is connected to the liquid phase inlet of the negative pressure generator (5) through a waste acid delivery pipeline (16); a waste acid component detector (14) is provided on the waste acid delivery pipeline (16); the waste acid component detector (14) is connected to a dosing controller (2) and is used to feed back the concentration of the detected waste acid component to the dosing controller (2); a reaction tank pressure gauge (13) is provided on the top of the reaction tank (6); the reaction tank pressure gauge (13) is connected to the dosing controller (2) and is used to feed back the pressure detected by the reaction tank pressure gauge (13) to the dosing controller (2); the outlet of the dosing unit (1) is connected to the second inlet of the mixing device through a drug delivery pipeline (10); a drug regulating valve (12) is provided on the drug delivery pipeline (10); the dosing controller (2) is connected to the drug regulating valve (12) and is used to control the opening of the drug regulating valve (12).

4. The waste acid treatment system based on vacuum degassing according to claim 3, characterized in that: The mixing device comprises a first mixer (29), a second mixer (30) and a third mixer (31); the first mixer (29) is provided with a first inlet and a second inlet; the second mixer (30) is provided with a first inlet and a second inlet; the third mixer (31) is provided with a first inlet and a second inlet; the first inlet of the first mixer (29), the first inlet of the second mixer (30) and the first inlet of the third mixer (31) are respectively connected to the outlet of the negative pressure forming device (5); the second inlet of the first mixer (29), the second inlet of the second mixer (30) and the third mixer (31) are respectively connected to the outlet of the negative pressure forming device (5); The second inlet of the device (31) is respectively connected to the outlet of the drug delivery pipeline (10), and the reaction tank (6) is provided with three feed ports, namely a first feed port, a second feed port and a third feed port. The first feed port is connected to the outlet of the first mixer (29), the second feed port is connected to the outlet of the second mixer (30), and the third feed port is connected to the outlet of the third mixer (31). The first feed port, the second feed port and the third feed port of the reaction tank (6) are all provided with an inclined feed pipe (19), and the angle between the inclined feed pipe (19) and the side wall of the reaction tank (6) is 30° to 60° upward.

5. The waste acid treatment system based on vacuum degassing according to claim 3, characterized in that: The waste acid delivery pipeline (16) is provided with a waste acid regulating valve (3), a waste acid flow meter (17) and a waste acid pressure gauge (28); the waste acid flow meter (17) is connected to the waste acid regulating valve (3) and is used to feed back the waste acid flow detected by the waste acid flow meter (17) to the waste acid regulating valve (3); and the reagent delivery pipeline (10) is provided with a reagent flow meter (11).

6. The waste acid treatment system based on vacuum degassing according to claim 3, characterized in that: The reaction tank (6) is provided with a stirrer (21) and a discharge pipe (20), wherein the stirrer (21) is connected to a reaction tank motor (15), and the discharge pipe (20) is communicated with a feed port of the vacuum tower (7); the tower kettle (24) of the vacuum tower (7) is provided with a sloping bottom (27), wherein the slope of the sloping bottom (27) is 10° to 20°, and a drainage pump (25) is provided at the bottom of the slope of the sloping bottom (27); and a defoamer (26) is provided at the top of the vacuum tower (7).

7. The waste acid treatment system based on vacuum degassing according to any one of claims 4 to 6, characterized in that: The negative pressure generator (5) is a venturi ejector or a water-flushed vacuum pump, the waste acid component detector (14) is an arsenic concentration online detection instrument, the first mixer (29), the second mixer (30), and the third mixer (31) are blade mixers or spiral mixers, the reaction tank (6) is made of acid corrosion resistant material, and the acid corrosion resistant material includes one or more of titanium, fiberglass, rubber lining, and fluorine lining, the pressure reducing tower (7) is an empty tower or a packed tower, and the demister (26) is a wire mesh demister or a baffle demister.

8. A method for treating waste acid based on vacuum degassing, characterized in that: The waste acid treatment system based on vacuum degassing according to any one of claims 1 to 7 is implemented, comprising the following steps: The waste acid is sent to the mixing device through the waste acid input unit (4) and the negative pressure generator (5), and the waste acid is arsenic-containing waste acid. The sulfiding agent is sent to the mixing device through the dosing unit (1). The waste acid and the sulfiding agent are mixed in the mixing device. The resulting mixed liquid is sent to the reaction tank (6) for sulfidation reaction. The reaction tank (6) is controlled under a micro-positive pressure condition of 400Pa to 600Pa. After the reaction, the obtained sulfidation reaction liquid is sent to the vacuum tower. (7), the vacuum tower (7) is controlled under a vacuum condition of 6 kPa to 50 kPa by the negative pressure generator (5), so that the sulfiding agent in the liquid after the sulfidation reaction is resolved to achieve vacuum degassing. The sulfiding agent obtained after the resolution is returned to the negative pressure generator (5), mixed with the waste acid from the waste acid input unit (4), and then sent to the reaction tank (6) through the mixing device to continue the reaction. The degassed liquid obtained after the resolution is discharged from the vacuum tower (7), and finally the waste acid is treated.

9. The method for treating waste acid based on vacuum degassing according to claim 8, characterized in that: The sulfiding agent includes one or more of sodium sulfide, sodium hydrosulfide and hydrogen sulfide gas; and / or the concentration of arsenic ions in the arsenic-containing waste acid is 4000 mg / L to 12000 mg / L.

10. The method for treating waste acid based on vacuum degassing according to claim 8 or 9, characterized in that: The material flow rate sent to the mixing device is controlled at 1.0m / s to 2.0m / s, the material residence time in the reaction tank (6) is controlled at 10min to 30min, and the liquid spray density of the liquid after the sulfidation reaction in the vacuum tower (7) is controlled at 10m 3 / (m 2 ·h)~30m 3 / (m 2 h).

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