A method and device for non-discharge treatment of hydrochloric acid pickling waste liquid

Abstract

The application discloses a kind of hydrochloric acid pickling solution's no discharge processing method and its device, processing method includes the following steps: (1) using iron oxide sand to neutralize the hydrochloric acid in pickling after waste water, and filter organic matter and solid impurities in waste water;(2) to the waste water after neutralization filtration, add coagulant, carry out solid-liquid separation;(3) further processing after the overflow clear liquid is passed through reverse osmosis system, the pure water that flows out is recycled to pickling production line, and the concentrated waste liquid that flows out is mixed with the waste water after step (1) pickling and is recycled;(4) the waste acid after pickling is sent into acid regeneration system and occurs hydrolysis reaction, and the regenerated hydrochloric acid generated is recycled to pickling production line.The application processing method combines waste acid regeneration technology with reverse osmosis membrane technology, has the advantages of high process reliability, low waste acid purity requirement, wide application range, no secondary pollution and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the sewage treatment technical field, especially to a kind of hydrochloric acid pickling solution's no discharge processing method and its device. BACKGROUND

[0002] One important link in metal surface treatment process is pickling, and hydrochloric acid is widely used as pickling medium, with high pickling efficiency, small damage to metal substrate, and high product metal surface quality, so it is widely used. Pickling treatment produces two kinds of waste liquid: waste acid with hydrochloric acid concentration below 6% and ferrous chloride concentration above 10%, and waste water with hydrochloric acid concentration below 3% and ferrous chloride concentration below 5%.

[0003] The harmless treatment of waste acid generally uses full acid regeneration technology, which can recover more than 99% of the chloride ions in waste acid and combine into hydrogen chloride, which is absorbed by water to form a saturated hydrogen chloride solution, i.e. regenerated hydrochloric acid; and all metal ions in waste acid, mainly iron ions, form by-products that can be recycled in the form of metal oxides.

[0004] The treatment of waste water, except for part of it supplied to the acid regeneration unit to absorb hydrogen chloride gas to generate regenerated acid, the rest generally uses neutralization, precipitation and dehydration process to neutralize the hydrochloric acid in the waste water with alkali, and generate ferrous hydroxide, which is oxidized by aeration and then precipitated with a flocculating agent to form solid waste residue for landfill treatment. The squeezed clear water has high salt content and must be desalted before it has any value, otherwise it will be directly discharged, causing salinization of water systems and damage to the environment.

[0005] Using reverse osmosis process to treat waste water can recover most of the water in waste water to generate pure industrial water with good recycling value, but the concentrated waste liquid still needs to be solidified into waste residue for discharge. Moreover, due to the presence of hydrochloric acid, organic impurities and other solid substances such as crystals in the waste water, it must be pretreated before reverse osmosis, which also generates contaminated waste liquid that must be solidified into waste residue.

[0006] In summary, because hydrochloric acid is used as a process medium in many metal pickling production processes, a large amount of waste acid and acid-containing waste water is generated during the pickling process. In order to eliminate the serious damage of these waste liquids to the water environment, special equipment must be used to treat the waste liquids. The current method is to neutralize the waste water, so the waste water treatment will generate a large amount of soluble harmful waste residue, causing secondary pollution to the environment. SUMMARY

[0007] The present application provides a kind of hydrochloric acid pickling solution's no discharge processing method and its device to solve the problem of neutralizing waste water in the prior art to generate a large amount of soluble harmful waste residue and cause secondary pollution to the environment.

[0008] The present application firstly provides a new process method, i.e. a non-discharge treatment method of hydrochloric acid pickling solution, which effectively solves the problem of waste residue discharge of hydrochloric acid pickling line wastewater treatment by combining waste acid regeneration technology with reverse osmosis membrane technology, and improves the operation benefit of waste liquid treatment facilities.

[0009] The present application also provides a non-discharge treatment device for the above-mentioned treatment method of hydrochloric acid pickling solution, which combines a fluidized bed acid regeneration device and a reverse osmosis purification device and applies them to the treatment device of the present application, effectively recycles and reuses the concentrated waste liquid, wastewater and waste residue generated in each process step, effectively solves the problems of wastewater treatment and waste residue generation, and realizes the purpose of non-discharge treatment of pickling waste liquid of the pickling production line.

[0010] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0011] The first aspect of the present application is to provide a non-discharge treatment method of hydrochloric acid pickling solution, which specifically comprises the following steps:

[0012] (1) neutralizing the hydrochloric acid in the wastewater after pickling by using iron oxide sand, and filtering the organic matter and solid impurities in the wastewater, controlling the neutralized wastewater to be weakly acidic, and the neutralization reaction is:

[0013] Fe2O3+6HCl→2FeCl3+3H2O;

[0014] (2) adding a coagulant to the neutralized and filtered wastewater, performing solid-liquid separation, and obtaining a suspended particulate matter precipitate and an overflow liquid;

[0015] (3) further treating the overflow liquid through a reverse osmosis system, recycling the pure water flowing out to the pickling production line, and mixing the concentrated waste liquid flowing out with the wastewater after pickling in step (1) for recycling treatment;

[0016] (4) sending the waste acid after pickling into an acid regeneration system, and the ferrous chloride in the waste acid undergoes a thermal hydrolysis reaction with water and oxygen at a high temperature greater than 600℃:

[0017] 4FeCl2+O2+4H2O→8HCl+2Fe2O3;

[0018] Other metals in the waste acid are solidified in the generated by-product iron oxide sand, the generated hydrogen chloride gas is absorbed by the wastewater after pickling, and the regenerated hydrochloric acid is recycled to the pickling production line.

[0019] Further, in the non-discharge treatment method of hydrochloric acid pickling solution, in step (1), the pH value of the neutralized and filtered wastewater is controlled to be 4 to 7.

[0020] Further, in the said non-discharge treatment method of hydrochloric acid pickling solution, the iron oxide sand used in the step (1) is derived from the by-product iron oxide sand generated in the step (4).

[0021] Further, in the said non-discharge treatment method of hydrochloric acid pickling solution, the ferrous chloride in the waste acid in the step (4) is subjected to thermal hydrolysis reaction with water and oxygen at a high temperature of 800-900℃.

[0022] Further, in the said non-discharge treatment method of hydrochloric acid pickling solution, the concentration of the regenerated hydrochloric acid in the step (4) is 15-30%.

[0023] Further, in the said non-discharge treatment method of hydrochloric acid pickling solution, the solid impurities after filtration in the step (1) and / or the suspended particulate matter precipitated after solid-liquid separation in the step (2) are mixed with the waste acid after pickling in the step (4) for recycling treatment.

[0024] The second aspect of the present application is to provide a non-discharge treatment device for hydrochloric acid pickling solution, mainly comprising:

[0025] a regenerated acid storage tank 21, a waste acid storage tank 22, a waste water storage tank 23, a recycled water storage tank 24 and a steam boiler 3 connected to the acid pickling production line 1 respectively;

[0026] a neutralization sand filter tank 4 connected to the waste water storage tank 23 for neutralizing hydrochloric acid in the waste water and filtering solid impurities and organic matter in the waste water;

[0027] a precipitation tank 5 connected to the neutralization sand filter tank 4 for further solid-liquid separation of the waste water after neutralization and filtration in the neutralization sand filter tank 4;

[0028] a reverse osmosis purification device 9 connected to the precipitation tank 5 for reverse osmosis purification of the waste water after solid-liquid separation; the reverse osmosis purification device 9 is connected to the waste acid storage tank 22 and the recycled water storage tank 24 respectively; and

[0029] a fluidized bed acid regeneration device 10 connected to the regenerated acid storage tank 21, the waste acid storage tank 22 and the waste water storage tank 22 respectively for regenerating hydrochloric acid and storing the regenerated hydrochloric acid in the regenerated acid storage tank 21 for use by the acid pickling production line 1.

[0030] Further, in the said non-discharge treatment device for hydrochloric acid pickling solution, the recycled water storage tank 24 is connected to the steam boiler 3 for providing water for acid pickling steam for the acid pickling production line 1.

[0031] Further, the non-discharge treatment device for hydrochloric acid pickling solution further comprises a concentrated liquid tank 7 connected with the neutralization sand filter tank 4 and the precipitation tank 5 respectively, and the concentrated liquid tank 7 is connected with the waste acid storage tank 22.

[0032] Further, the non-discharge treatment device for hydrochloric acid pickling solution further comprises an iron oxide sand storage tank 8 connected with the fluidized bed acid regeneration device 10, and the iron oxide sand storage tank 8 stores the iron oxide sand generated by the fluidized bed acid regeneration device 10.

[0033] Further, the non-discharge treatment device for hydrochloric acid pickling solution is provided with an intermediate tank 6 for storing waste water clear liquid between the precipitation tank 5 and the reverse osmosis purification device 9.

[0034] Compared with the prior art, the non-discharge treatment device for hydrochloric acid pickling solution has the following technical effects:

[0035] Compared with other acid regeneration processes, the non-discharge treatment method for hydrochloric acid pickling solution has the advantages of high process reliability, low purity requirement for waste acid, wide application range, no secondary pollution, etc. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The non-discharge treatment method for hydrochloric acid pickling solution is a process flow chart.

[0037] 1-acid pickling production line, 2-liquid storage tank, 21-regenerated acid storage tank, 22-waste acid storage tank, 23-waste water storage tank, 24-reused water storage tank, 3-steam boiler, 4-neutralization sand filter tank, 5-precipitation tank, 6-intermediate tank, 7-concentrated liquid tank, 8-iron oxide sand storage tank, 9-reverse osmosis purification device, and 10-fluidized bed acid regeneration device. DETAILED DESCRIPTION

[0038] The following specific examples are used to introduce the present application in detail and specifically, so that the present application can be better understood.

[0039] The non-discharge treatment method for hydrochloric acid pickling solution provided by the embodiment of the present application comprises the following steps:

[0040] (1) using the iron oxide sand to neutralize the hydrochloric acid in the waste water after pickling, and filtering the organic matter and solid impurities in the waste water, controlling the neutralized waste water to be weakly acidic to meet the requirements of the reverse osmosis membrane, and the chemical reaction formula of the neutralization reaction is:

[0041] Fe2O3 + 6HCl → 2FeCl3 + 3H2O;

[0042] (2) adding a coagulant to the neutralized and filtered waste water, performing solid-liquid separation, precipitating and separating the fine suspended particles from the clear liquid to eliminate the damage of the particles to the reverse osmosis membrane, and obtaining the suspended particles and the overflow clear liquid;

[0043] (3) further processing the overflow clear liquid through a reverse osmosis system, recycling the pure water flowing out to the pickling production line, and mixing the concentrated waste liquid flowing out with the waste water after pickling in step (1) for recycling treatment;

[0044] (4) sending the waste acid after pickling to an acid regeneration system, and performing a thermal hydrolysis reaction of ferrous chloride in the waste acid with water and oxygen at high temperature:

[0045] 4FeCl2 + O2 + 4H2O → 8HCl + 2Fe2O3;

[0046] other metals in the waste acid are solidified in the generated byproduct iron oxide sand, the generated hydrogen chloride gas is absorbed by the waste water after pickling, and the regenerated hydrochloric acid is recycled to the pickling production line.

[0047] On the basis of the above technical scheme, in step (1) of the no-discharge treatment method of the hydrochloric acid pickling solution, the pH value of the neutralized and filtered waste water is controlled to be 4 to 7; preferably, the pH value of the neutralized and filtered waste water is controlled to be 5.5 to 6.5.

[0048] On the basis of the above technical scheme, in step (1) of the no-discharge treatment method of the hydrochloric acid pickling solution, the iron oxide sand used is all derived from the byproduct iron oxide sand generated in step (4).

[0049] On the basis of the above technical scheme, in step (4) of the no-discharge treatment method of the hydrochloric acid pickling solution, the thermal hydrolysis reaction of ferrous chloride in the waste acid with water and oxygen is performed at a high temperature of 800-900℃; preferably, the high temperature is 860-880℃.

[0050] On the basis of the above technical scheme, in step (4) of the no-discharge treatment method of the hydrochloric acid pickling solution, the concentration of the regenerated hydrochloric acid is 15-30%; preferably, the concentration of the regenerated hydrochloric acid is 18% for use in the metal pickling production line.

[0051] On the basis of the above technical solution, the solid impurities filtered in step (1) and / or the suspended particulate matter precipitated after the solid-liquid separation in step (2) of the hydrochloric acid pickling solution non-discharge treatment method are mixed with the waste acid after the pickling in step (4) for recycling treatment.

[0052] The embodiment of the present application also provides a hydrochloric acid pickling solution non-discharge treatment device, and material is delivered between components through a pump or a high-pressure pump, which mainly comprises: a regenerated acid storage tank 21, a waste acid storage tank 22, a waste water storage tank 23, a recycled water storage tank 24 and a steam boiler 3 connected with the pickling production line 1 respectively; a neutralization sand filter tank 4 connected with the waste water storage tank 23, used for neutralizing hydrochloric acid in waste water and filtering solid impurities and organic matter in waste water; a sedimentation tank 5 connected with the neutralization sand filter tank 4, used for further solid-liquid separation of waste water after neutralization and filtration in the neutralization sand filter tank 4; a reverse osmosis purification device 9 connected with the sedimentation tank 5, used for reverse osmosis purification of waste water after solid-liquid separation; the reverse osmosis purification device 9 is connected with the waste acid storage tank 22 and the recycled water storage tank 24 respectively; and a fluidized bed acid regeneration device 10 connected with the regenerated acid storage tank 21, the waste acid storage tank 22 and the waste water storage tank 22 respectively, used for regenerating hydrochloric acid and storing the regenerated hydrochloric acid in the regenerated acid storage tank 21 for use of the pickling production line 1.

[0053] On the basis of the above technical solution, the recycled water storage tank 24 is connected with the steam boiler 3 on the hydrochloric acid pickling solution non-discharge treatment device, used for providing pickling steam water for the pickling production line 1.

[0054] On the basis of the above technical solution, the hydrochloric acid pickling solution non-discharge treatment device further comprises a concentrated liquid tank 7 connected with the neutralization sand filter tank 4 and the sedimentation tank 5 respectively, and the concentrated liquid tank 7 is connected with the waste acid storage tank 22.

[0055] On the basis of the above technical solution, the hydrochloric acid pickling solution non-discharge treatment device further comprises an iron oxide sand storage tank 8 connected with the fluidized bed acid regeneration device 10, and the iron oxide sand storage tank 8 stores iron oxide sand generated by the fluidized bed acid regeneration device 10.

[0056] On the basis of the above technical solution, the hydrochloric acid pickling solution non-discharge treatment device further comprises an intermediate tank 6 for storing waste water clear liquid between the sedimentation tank 5 and the reverse osmosis purification device 9.

[0057] The hydrochloric acid pickling solution non-discharge treatment process using the non-discharge treatment device of the present application is as follows:

[0058] The waste acid and waste water generated by the pickling production line 1 are respectively stored in the waste acid storage tank 22 and the waste water storage tank 23.

[0059] First, the wastewater needs to be pre-cleaned, the wastewater is pumped from the wastewater storage tank 23 to the sand filter tank 4, the sand filter tank 4 uses iron oxide sand from the iron oxide sand storage tank 8, the hydrochloric acid in the wastewater is neutralized by the iron oxide sand, and the following chemical reaction occurs:

[0060] Fe2O3+6HCl->2FeCl3+3H2O;

[0061] After neutralization, the pH of the wastewater is weakly acidic between 4 and 7, which meets the requirements of the reverse osmosis membrane; the sand filter tank 4 simultaneously removes larger solid impurities from the wastewater to the concentrated liquid tank 7; at the same time, the neutralized and filtered wastewater flows into the sedimentation tank 5, a coagulant is added, and the suspended particles are precipitated and discharged to the concentrated liquid tank 7 at regular intervals to eliminate the damage of these substances to the reverse osmosis membrane, so that the wastewater meets the requirements of the reverse osmosis membrane in the reverse osmosis purification device.

[0062] Then, the overflow liquid from the sedimentation tank 5 is transported into the intermediate tank 6, and the wastewater liquid is pumped from the intermediate tank 6 to the reverse osmosis purification device 9 for reverse osmosis purification treatment by a high-pressure pump, the pure water from the reverse osmosis purification device 9 flows into the recycled water tank 24 for use by the pickling production line 1; while the concentrated wastewater from the reverse osmosis purification device 9 flows into the wastewater tank 23 for use by the acid regeneration device 10 or the reverse osmosis purification device 9.

[0063] Finally, the spent acid after pickling is pumped from the spent acid storage tank 22 to the acid regeneration device 10, in which the ferrous chloride in the spent acid undergoes a thermal hydrolysis reaction with water and oxygen at high temperature:

[0064] 4FeCl2+O2+4H2O->8HCl+2Fe2O3;

[0065] The generated hydrogen chloride gas is absorbed by the wastewater from the wastewater storage tank 23, producing regenerated hydrochloric acid with a concentration of 18% and being sent to the regenerated acid storage tank 21 for use by the pickling production line 1; while the generated iron oxide sand is sent to the iron oxide sand storage tank 8 to provide neutralized hydrochloric acid for the sand filter tank 4 or for other purposes, and other metal impurities in the spent acid are solidified in the iron oxide sand, which is harmless to the environment.

[0066] The above describes the specific embodiments of the present application in detail, but it is only as an example, the present application is not limited to the specific embodiments described above. Any equivalent modification and replacement of the present application made by those skilled in the art is also within the scope of the present application. Therefore, any equivalent transformation and modification made without departing from the spirit and scope of the present application should be covered within the scope of the present application.

Claims

1. A method for emissionless treatment of a hydrochloric acid pickle liquor, characterized in that, The method comprises the following steps: (1) neutralizing hydrochloric acid in the waste water after pickling by using iron oxide sand, filtering organic substances and solid impurities in the waste water, controlling the waste water after neutralization to be weakly acidic, and the neutralization reaction being: Fe2O3+ 6HCl → 2FeCl3 + 3H2O; (2) adding a coagulant to the waste water after neutralization and filtration, performing solid-liquid separation, and obtaining a suspended particulate matter precipitate and an overflow liquid; (3) further processing the overflow liquid by a reverse osmosis system, recycling pure water flowing out of the reverse osmosis system to a pickling production line, and mixing concentrated waste liquid flowing out of the reverse osmosis system with the waste water after pickling in step (1) for recycling treatment; (4) sending the waste acid after pickling to an acid regeneration system, and performing a thermal hydrolysis reaction of ferrous chloride in the waste acid with water and oxygen at a high temperature greater than 600℃: 4FeCl2 + O2 + 4H2O → 8HCl + 2Fe2O3; other metals in the waste acid are solidified in the generated by-product iron oxide sand, and generated hydrogen chloride gas is absorbed by the waste water after pickling, and regenerated hydrochloric acid is recycled to the pickling production line; the solid impurities after filtration in step (1) and / or the suspended particulate matter precipitate after solid-liquid separation in step (2) are mixed with the waste acid after pickling in step (4) for recycling treatment.

2. The method of claim 1, wherein the hydrochloric acid pickle liquor is treated without emission, characterized in that, In step (1), the pH value of the waste water after neutralization and filtration is controlled to be 4 to 7.

3. The method of claim 1, wherein the hydrochloric acid pickle liquor is treated without emission, characterized in that, The iron oxide sand used in step (1) is derived from the by-product iron oxide sand generated in step (4).

4. The method of claim 1, wherein the hydrochloric acid pickle liquor is treated without emission. In step (4), the concentration of the regenerated hydrochloric acid is 15-30%.

5. A salt acid pickling solution emission-free treatment device characterized by comprising: The method comprises the following steps: a regenerated acid storage tank (21), a waste acid storage tank (22), a waste water storage tank (23), a recycled water storage tank (24) and a steam boiler (3) connected to the pickling production line (1) respectively; a neutralization sand filter tank (4) connected to the waste water storage tank (23) and used for neutralizing hydrochloric acid in the waste water and filtering solid impurities and organic substances in the waste water; a precipitate tank (5) connected to the neutralization sand filter tank (4) and used for further performing solid-liquid separation on the waste water after neutralization and filtration in the neutralization sand filter tank (4); a reverse osmosis purification device (9) connected to the precipitate tank (5) and used for performing reverse osmosis purification on the waste water after solid-liquid separation; the reverse osmosis purification device (9) is connected to the waste acid storage tank (22) and the recycled water storage tank (24) respectively; and a fluidized bed acid regeneration device (10) connected to the regenerated acid storage tank (21), the waste acid storage tank (22) and the waste water storage tank (22) respectively, and used for regenerating hydrochloric acid and storing the regenerated hydrochloric acid in the regenerated acid storage tank (21) for use of the pickling production line (1).

6. The apparatus for emissionless treatment of a hydrochloric acid pickle liquor according to claim 5, characterized in that, The recycled water storage tank (24) is connected to the steam boiler (3) and used for providing water for pickling steam for the pickling production line (1).

7. The apparatus for emissionless treatment of a hydrochloric acid pickle liquor according to claim 5, characterized in that, The method further comprises a concentrated liquid tank (7) connected to the neutralization sand filter tank (4) and the precipitate tank (5) respectively, and the concentrated liquid tank (7) is connected to the waste acid storage tank (22).

8. The apparatus for emissionless treatment of a hydrochloric acid pickle liquor according to claim 5, characterized in that, The method further comprises an iron oxide sand storage tank (8) connected to the fluidized bed acid regeneration device (10).

9. The apparatus for emissionless treatment of a hydrochloric acid pickle liquor according to claim 5, characterized in that, The sedimentation tank (5) and the reverse osmosis purification device (9) are provided with an intermediate tank (6) for storing wastewater supernatant.

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