Method and device for recycling acid-containing washing water

Abstract

The invention provides a cyclic utilization method and device of acid-containing washing water, and the method comprises the following steps: carrying out reverse osmosis on the acid-containing washing water to obtain a filtrate and a trapped fluid; wherein the trapped fluid comprises chloride ions and silicate ions trapped in the reverse osmosis process and metal ions on the surface of strip steel; the acid-containing washing water comprises an acid mist washing solution and / or rinsing water after strip steel pickling; absorbing furnace gas by using the trapped fluid to obtain regenerated acid; the furnace gas comprises HCl gas; and treating the filtrate through a cation bed, an anion bed and a mixed bed in sequence to obtain desalted water. In the cyclic utilization method of the acid-containing washing water, the trapped fluid absorbs the furnace gas to obtain the regenerated acid, so that the salt substances and the free acid are utilized as components of the regenerated acid, the loss rate of acid circulation of acid pickling and acid regeneration is reduced, and hydrochloric acid is regenerated during acid regeneration by recycling chloride ions. The filtrate is treated by the cation bed, the anion bed and the mixed bed to obtain desalted water, so that the preparation process of the desalted water is shortened, and the filtrate is recycled.

Description

Technical Field

[0001] The invention relates to the field of acid-containing wastewater treatment, and in particular to a method and device for recycling acid-containing washing water. Background Art

[0002] The hot-rolled strip enters the pickling unit (such as a continuous pickling unit, a push-pull pickling unit) and passes through the three-stage pickling section or the four-stage pickling section. The acid mist generated is entrained and sucked into the two-stage self-circulating acid mist washing tower for washing. The washing medium used is desalted water supplied by the workshop pipe network. The desalted water has low conductivity and has the ability to continuously wash and absorb chloride ions in the acid mist and ensure that the acid mist discharge meets the standards. After the desalted water reaches saturation in the self-circulation (when the free acidity reaches 5g / L), an acid mist washing liquid is formed. Most of the acid mist washing liquid is discharged into the wastewater treatment station as acid-containing wastewater for treatment.

[0003] However, this treatment method has high treatment costs for wastewater treatment plants, and although the treated wastewater meets the standards, it has a high salt content. Summary of the invention

[0004] The main purpose of the present invention is to provide a method and device for recycling acid-containing washing water to solve the technical problems of high treatment cost in conventional treatment methods and high salinity in the treated wastewater even though it meets the standards.

[0005] To achieve the above object, the present invention provides a method for recycling acid-containing washing water, comprising the following steps:

[0006] The acid-containing washing water is subjected to reverse osmosis to obtain a filtrate and a retentate. The retentate includes chloride ions, silicate ions and metal ions on the surface of the steel strip retained during the reverse osmosis process. The acid-containing washing water includes acid mist washing liquid and / or rinsing water, and the rinsing water is the rinsing water after the steel strip is pickled.

[0007] The retentate absorbs the furnace gas to obtain the regenerated acid. The furnace gas includes HCl gas.

[0008] The filtrate is treated in sequence by a cation bed, anion bed and mixed bed to obtain desalted water.

[0009] According to an embodiment of the present application, in the step of performing reverse osmosis on the acid-containing washing water, the chloride ion removal rate is ≥98%, and the conductivity of the produced water is ≤30 microSiemens / cm.

[0010] According to an embodiment of the present application, the concentration ratio of the acid-containing washing water is 2 to 3 times.

[0011] According to the implementation mode of the present application, it also includes:

[0012] The reverse osmosis membrane is cleaned with membrane tube cleaning fluid, and the waste liquid generated by the cleaning is discharged into the cold rolling wastewater treatment station for treatment.

[0013] According to an embodiment of the present application, the step of absorbing the furnace gas with the retentate to obtain the regenerated acid comprises:

[0014] The furnace gas is cooled, and the retentate is absorbed by the cooled furnace gas to obtain the regenerated acid.

[0015] According to the implementation mode of the present application, it also includes:

[0016] The regenerated acid is used to perform multi-stage pickling on the steel strip to obtain a pickling solution, wherein the multi-stage pickling process includes a pre-desiliconization treatment.

[0017] The pickled solution is heated in sequence, the scrap steel is soaked, the pH of the soaked solution is adjusted to 3.5-4.4, and then the treated acid is obtained by precipitation and separation. The treated acid is a ferrous chloride solution.

[0018] The treated acid is concentrated by a heat exchange mechanism and then enters a roasting furnace to obtain furnace gas.

[0019] According to the implementation mode of the present application, it also includes:

[0020] The desalted water continuously replaces the acid mist washing liquid, and the replaced acid mist washing liquid forms the acid-containing washing water, wherein the acid mist washing liquid is a washing liquid formed by the desalted water absorbing chloride ions of the acid mist.

[0021] The present application also provides a recycling device for acid-containing washing water, comprising:

[0022] The reverse osmosis component has a reverse osmosis membrane, a filtration port and a retention port. It is used to reverse osmosis the acid-containing washing water to obtain a filtrate and a retention liquid. The retention liquid includes chloride ions, silicate ions and metal ions on the surface of the strip retained during the reverse osmosis process. The acid-containing washing water includes acid mist washing liquid and / or rinsing water, and the rinsing water is the rinsing water after the strip is pickled.

[0023] The absorption tower has a furnace gas inlet and an absorption liquid inlet, wherein the furnace gas inlet is used to introduce furnace gas, and the absorption liquid inlet is connected to the interception port to absorb the furnace gas with the interception liquid to obtain regenerated acid. The furnace gas includes HCl gas.

[0024] A cation bed, anion bed and mixed bed are connected in sequence, and the cation bed is connected to the filtration port, so as to process the filtrate in sequence through the cation bed, anion bed and mixed bed to obtain desalted water.

[0025] According to the implementation mode of the present application, it also includes:

[0026] The acid mist washing tower comprises an acid mist inlet, a primary washing component and a secondary washing component, wherein the secondary washing component is located above the first washing component.

[0027] The primary washing tank circulates with the primary washing component to absorb the chloride ions in the acid mist to form a primary washing liquid. The primary washing tank continuously introduces desalted water to replace the primary washing liquid, and the replaced primary washing liquid forms the acid-containing washing water.

[0028] The secondary washing tank circulates with the secondary washing component to absorb the chloride ions in the acid mist to form a secondary washing liquid. The secondary washing tank continuously introduces desalted water to replace the secondary washing liquid, and the replaced secondary washing liquid forms the acid-containing washing water.

[0029] According to the implementation mode of the present application, it also includes:

[0030] The multi-stage pickling mechanism has a pre-desiliconization component. The multi-stage pickling mechanism is used to carry out multi-stage pickling of the strip steel with the regenerated acid to obtain a post-pickling liquid. The multi-stage pickling process includes a pre-desiliconization treatment.

[0031] The sequentially arranged leaching tower, reaction tank, sedimentation tank, heat exchanger and roasting furnace are used to heat the pickling solution in sequence, leaching scrap steel, adjusting the pH of the leached solution to 3.5-4.4, precipitating and separating to obtain treatment acid, concentrating the treatment acid, and then roasting to obtain furnace gas, wherein the treatment acid is ferrous chloride solution.

[0032] In the above-mentioned recycling method of acid-containing washing water, the acid-containing washing water is subjected to reverse osmosis and classified treatment. The retentate absorbs the furnace gas to obtain regenerated acid, so that salt substances and free acid can be used as components of the regenerated acid, reducing the loss rate of the acid cycle of pickling and acid regeneration, and realizing the recovery of chloride ions to regenerate hydrochloric acid in acid regeneration. The filtrate does not contain elemental ions in steel such as chloride ions, iron ions, silicate ions, and manganese ions. Desalted water is obtained after treatment with a cation bed, anion bed, and mixed bed, shortening the preparation process of desalted water and realizing the recycling of desalted water and filtrate. The above-mentioned recycling method of acid-containing washing water fully improves the utilization rate of acid-containing washing water, avoids it from being directly discharged into a wastewater treatment station as acid-containing wastewater, reduces the treatment cost, and reduces the salt content in the wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0034] Figure 1It is a schematic diagram of the operation of a recycling device for acid-containing washing water according to one embodiment of the present application.

[0035] Figure 2 It is a schematic diagram of a recycling device for acid-containing washing water according to one embodiment of the present application.

[0036] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings.

[0037] 100, reverse osmosis assembly; 200, absorption tower; 300, cation bed; 400, anion bed; 500, mixed bed; 700, acid mist scrubber; 800, primary scrubber; 900, secondary scrubber

[0038] 610, multi-stage pickling mechanism; 620, leaching tower; 630, reaction tank; 640, sedimentation tank; 650, heat exchanger; 660, roasting furnace; 710, primary washing component; 720, secondary washing component. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0041] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0042] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0043] The applicant has found that the acid mist washing liquid is relatively pure, mainly because the desalted water contains free acidity of 2-5g / L, a small amount of iron ions (0-50mg / L) and a very small amount of elemental ions in steel such as silicate ions and manganese ions. The acid mist washing liquid is discharged into the wastewater treatment station as acid-containing wastewater, which causes the chloride ions in the acid solution to gradually decrease between pickling and acid regeneration, and the high treatment cost caused by the discharge into the wastewater treatment station, and the wastewater after treatment meets the standards but has high salinity. According to the new national emission standards, the country has new requirements for the salt content in the wastewater after treatment. In addition, the utilization rate of desalted water is not high, and all-round utilization has not been achieved, resulting in waste of resources, and the production cost of desalted water is relatively high.

[0044] To achieve the above object, the present invention provides a method for recycling acid-containing washing water. Figure 1 and Figure 2 , including the following steps:

[0045] S100: The acid-containing washing water is subjected to reverse osmosis to obtain a filtrate and a retentate. The retentate includes chloride ions, silicate ions and metal ions on the surface of the steel strip retained during the reverse osmosis process. The acid-containing washing water includes acid mist washing liquid and / or rinsing water, and the rinsing water is the rinsing water after the steel strip is pickled.

[0046] The acid-containing washing water includes acid mist washing liquid and / or rinsing water. The acid mist washing liquid has been introduced in the background technology and will not be described in detail.

[0047] Rinsing water is the water used for rinsing the steel strip after pickling. Specifically, the steel strip after pickling enters the fourth or fifth stage of rinsing, and the medium used for rinsing is the condensed water produced after the heated desalted water mixed steam is heated (acid solution and desalted water). After continuous four or five stages of rinsing, a part of it is discharged into the acid-containing wastewater pit of pickling; the other part enters the rinsing water tank of acid regeneration and is used as acid regeneration rinsing water operation, acid solution preparation, etc. In this acid-containing wastewater pit, there are rinsing wastewater generated by the rinsing section, acid mist washing wastewater, and pickling acid regeneration drainage, etc. Several acid-containing wastewaters are discharged into the wastewater treatment station together. Relatively speaking, rinsing water also has a higher utilization value, and directly discharging it into the wastewater treatment station also faces the same problem as discharging acid-containing washing water into the wastewater treatment station. There are certain differences between acid mist washing liquid and rinsing water. The free acidity of rinsing water (2-10g / L) is slightly larger than that of acid mist washing liquid (free acidity 2-5g / L). Acid mist washing liquid does not contain silicate ions and metal ions on the surface of the strip, while rinsing water contains silicate ions and metal ions on the surface of the strip.

[0048] Exemplarily, the acid mist washing liquid and the rinsing water both enter the acid-containing washing water collection box and merge to obtain the acid-containing washing water.

[0049] The acid-containing washing water is subjected to reverse osmosis, and the chloride ions, silicate ions, and metal ions on the surface of the strip (such as iron ions and manganese ions) are retained by the reverse osmosis membrane due to their large molecules and remain in the retained liquid. The filtrate does not contain the above ions, and the hydrogen ion molecules are smaller and can pass through the reverse osmosis membrane into the filtrate.

[0050] S200: The retentate absorbs the furnace gas to obtain regenerated acid. The furnace gas includes HCl gas.

[0051] Since salt substances and free acid are still present in the retentate, they are illustratively stored and utilized by entering the acid regeneration rinse water tank. In some embodiments, HCl gas in the furnace gas is absorbed in the absorption tower 200 to become regenerated acid.

[0052] Generally speaking, the subsequent use process of regenerated acid is as follows: the regenerated acid becomes waste acid after pickling the strip steel, the waste acid is concentrated by Venturi heat, and then absorbed by the acid regeneration roasting furnace 660, and then absorbed by the absorption tower 200. The recovered chloride ions enter the regenerated acid, which slows down the decay of chloride ions in the cycle between pickling and acid regeneration. Cl - +H + =HCl.

[0053] In this way, the chloride ions in the acid-containing washing water enter the regenerated acid and are reused.

[0054] S300: The filtrate is sequentially treated by the cation bed 300, the anion bed 400 and the mixed bed 500 to obtain desalted water.

[0055] The filtrate enters the cation bed 300, anion bed 400 and mixed bed 500 of the desalting water station again for treatment due to the low pH value, and desalted water is obtained. For example, the filtrate enters the acid mist washing and rinsing process through the pipe network, and the cycle is continued.

[0056] The complete preparation process of conventional desalted water includes: using source water to precipitate through an inclined plate sedimentation tank 640 - filtering through a multi-media filter - filtering through a precision filter - filtering through a reverse osmosis membrane, and then sequentially processing through a cation bed 300, anion bed 400, and mixed bed 500 to obtain desalted water.

[0057] Overall, the above-mentioned recycling method of acid-containing washing water realizes the circulation of desalted water, improves the utilization rate of desalted water, realizes all-round utilization, and reduces resource waste. The continuous circulation of desalted water can ensure the operation of large amounts of desalted water washing strip steel and acid mist washing with low ion concentration.

[0058] Secondly, it reduces the discharge of acid liquid, lowers the loss rate of acid circulation during pickling and acid regeneration, and realizes the recovery of chloride ions to regenerate hydrochloric acid in acid regeneration.

[0059] Moreover, it meets the new national emission standards and reduces the salt content in wastewater.

[0060] In the above-mentioned recycling method of acid-containing washing water, the acid-containing washing water is subjected to reverse osmosis and classified treatment. The trapped liquid absorbs the furnace gas to obtain regenerated acid, so that salt substances and free acids can be used as components of the regenerated acid, reducing the loss rate of the acid cycle of pickling and acid regeneration, and realizing the recovery of chloride ions to regenerate hydrochloric acid in acid regeneration. The filtrate does not contain elemental ions in steel such as chloride ions, iron ions, silicate ions, and manganese ions. Desalted water is obtained after being treated by the cation bed 300, the anion bed 400, and the mixed bed 500, shortening the preparation process of desalted water. The above-mentioned recycling method of acid-containing washing water fully improves the utilization rate of acid-containing washing water, avoids it from being directly discharged into the wastewater treatment station as acid-containing wastewater, reduces the treatment cost, and reduces the salt content in the wastewater.

[0061] In some embodiments, in the step of performing reverse osmosis on the acid-containing washing water, the chloride ion removal rate is ≥98%, and the conductivity of the produced water is ≤30 microSiemens / cm.

[0062] In some embodiments, the concentration ratio of the acid-containing washing water is 2 to 3 times.

[0063] The concentration ratio of the reverse osmosis membrane refers to the volume ratio of the stock solution (acid-containing washing water) to the concentrated solution (retentate) during the reverse osmosis process. In this embodiment, the concentration ratio does not need to be large, and only 2-3 times is sufficient. The pressure of the acid-containing wastewater is not high enough to overcome the osmotic pressure, and the energy consumption of the reverse osmosis will not be high.

[0064] Moreover, in the subsequent acid regeneration process of the retentate, the amount of water that needs to be evaporated during the roasting process is lower, which also reduces energy consumption.

[0065] In some specific embodiments, see Figure 1 and Figure 2 The above concentration ratio is conducive to achieving water balance. The water balance relationship is that the rinsing water is about 12-14 cubic meters / hour, the first stage produces 3-4 cubic meters / hour of acid mist washing water, and the first stage produces acid mist washing water and the second stage produces acid mist washing water, which together produce about 6-8 cubic meters / hour of acid mist washing water. An acid regeneration unit that produces 10 cubic meters of regenerated acid per hour uses 10 cubic meters of acid-containing washing water per hour. At this time, according to the reverse osmosis operation mode with a concentration ratio of 2 times, rinsing and acid mist washing produce 20 cubic meters of acid-containing washing water. After reverse osmosis, 10 cubic meters of acid-containing washing water retentate is stored in the acid regeneration rinsing water tank for normal use of acid regeneration, and the other 10 cubic meters of filtrate enters the desalting water station to produce desalted water through circulation, thus maintaining water balance and achieving zero discharge. On the one hand, a too high concentration ratio is unnecessary, and on the other hand, it increases the energy consumption of water pump pressurization.

[0066] In some embodiments, see Figure 1 , also includes:

[0067] The reverse osmosis membrane is cleaned with membrane tube cleaning fluid, and the waste liquid generated by the cleaning is discharged into the cold rolling wastewater treatment station for treatment.

[0068] In this way, the volume of waste liquid treated by the cold rolling wastewater treatment station is greatly reduced, and the salt content in the waste liquid is also greatly reduced. After the treated wastewater meets the standards, the salt content is also lower.

[0069] In some embodiments, see Figure 1 and Figure 2 The step of using the retentate to absorb the furnace gas to obtain the regenerated acid comprises:

[0070] The furnace gas is cooled, and the retentate is absorbed by the cooled furnace gas to obtain the regenerated acid. In this step, since the temperature of the furnace gas is relatively high, such as 450°C, the absorption of the hydrogen chloride mist by the retentate is limited to a certain extent. Therefore, the furnace gas can be cooled in advance, such as cooling under heat exchange conditions. Exemplarily, the treatment acid and the furnace gas are heat exchanged in a venturi device, and the treatment acid cools the furnace gas. In the venturi device, the furnace gas is greatly reduced in temperature due to heat exchange, forming a cooled furnace gas, the temperature of which is about 90 to 95°C.

[0071] After the cooling gas enters the absorption tower 200, due to the low temperature and the structural setting of the absorption tower 200 is mainly for the consideration of promoting absorption, the cooling gas is fully in contact with the retentate after heat exchange, so the hydrogen chloride mist in the cooling gas can be more fully absorbed, thereby obtaining a regenerated acid with a high concentration of free acid (170-190g / l). In this way, two-stage absorption is achieved, the hydrogen chloride mist is absorbed more thoroughly, and the environmental pressure is reduced.

[0072] The temperature of the cooling furnace gas is relatively low, which is beneficial to the absorption of the hydrogen chloride gas therein and reduces the loss of hydrogen chloride due to failure to absorb. Secondly, it can reduce the influence of the cooling furnace gas on the absorption tower 200 and the fillers in the absorption tower 200. The material of the absorption tower 200 and the fillers in the absorption tower 200 is a high molecular polymer, which is easily deformed by heat at high temperature, affecting its life. And the deformation of the filler will also affect the absorption of the cooling furnace gas. Therefore, when the temperature of the cooling furnace gas is relatively low, it is beneficial to extend the service life of the absorption tower 200 and increase the absorption efficiency of the absorption tower 200 for the cooling furnace gas.

[0073] In this embodiment, the amount of unusable acid-containing washing water discharged into the wastewater station is reduced, the discharge of acidic wastewater is reduced, the cost of treating wastewater in the wastewater station is reduced, and the system emission reduction is achieved. In addition, the loss of acid retained in the pickling and acid regeneration systems is reduced, and acid losses are reduced.

[0074] In some embodiments, see Figure 1 and Figure 2 , also includes:

[0075] S400: The regenerated acid is used to perform multi-stage pickling on the steel strip to obtain a pickling solution, wherein the multi-stage pickling process includes a pre-desiliconization treatment.

[0076] The number of multi-stage pickling is 3 to 4, and a pre-desiliconization treatment is included between two stages of pickling to reduce the silicon content in the final pickling solution. The specific pre-desiliconization treatment includes directly adding flocculants to precipitate the silicon therein, and using a brush roller to remove the silica gel formed on the surface of the strip during the pickling process. The specific method will not be repeated here.

[0077] S500: heating the pickled solution in sequence, dissolving the scrap steel, adjusting the pH of the solution to 3.5-4.4, and then precipitating and separating to obtain a treatment acid, wherein the treatment acid is a ferrous chloride solution.

[0078] In this step, the pickling liquid can be heated by steam, which can accelerate the reaction speed of the pickling liquid in dissolving the scrap steel.

[0079] The scrap steel is dissolved, and the pickling liquid reacts with the edge wire to generate hydrogen and a dissolving solution. The dissolving solution includes a ferrous chloride solution generated by the reaction of the pickling liquid and the edge wire.

[0080] In the process of push-pull pickling and pickling-rolling, the corresponding pickling liquid reacts with the strip steel, so the pickling liquid also contains a large amount of ferrous chloride. In addition, the ferrous chloride solution is generated by the reaction of the pickling liquid and the edge wire.

[0081] After the leaching solution is added with ammonia water to adjust the pH value to 3.5-4.4, aeration is performed, and the supernatant is separated in the sedimentation tank 640, and the supernatant is the treatment acid. In this process, a flocculent iron hydroxide precipitate is generated. The iron hydroxide precipitate has an adsorption effect and can adsorb other impurities such as silicon in the leaching solution. Therefore, the supernatant is the treatment acid, which has fewer impurities and is basically a ferrous chloride solution. The treatment acid can be stored in a treatment acid tank.

[0082] S600: roasting the treated acid to obtain furnace gas.

[0083] When the treatment acid is roasted, the treatment acid is roasted under the condition of introducing air to obtain iron oxide powder and furnace gas. HCl gas is the main component of the furnace gas. The furnace gas here can be used as the furnace gas absorbed by the retentate in step S200.

[0084] In some embodiments, see Figure 1 and Figure 2 , also includes:

[0085] The desalted water continuously replaces the acid mist washing liquid, and the replaced acid mist washing liquid forms the acid-containing washing water, wherein the acid mist washing liquid is a washing liquid formed by the desalted water absorbing chloride ions of the acid mist.

[0086] During the acid mist washing process, desalted water continuously replaces the acid mist washing liquid so that the acid mist washing liquid is at a low free acidity, thereby ensuring the effect of the acid mist washing and further ensuring that the acid mist meets the environmental protection standards. Instead of the acid mist washing liquid being discharged only when the free acidity reaches 5g / L during the acid mist washing process, the acid mist washing liquid often has a reduced ability to absorb and wash the free acid in the acid mist when the free acidity reaches 5g / L.

[0087] The present application also provides a recycling device for acid-containing washing water, see Figure 1 and Figure 2 ,include:

[0088] The reverse osmosis component 100 has a reverse osmosis membrane, a filtration port and a retention port. It is used to reverse osmosis the acid-containing washing water to obtain a filtrate and a retention liquid. The retention liquid includes chloride ions, silicate ions and metal ions on the surface of the steel strip retained during the reverse osmosis process. The acid-containing washing water includes acid mist washing liquid and / or rinsing water, and the rinsing water is the water used for rinsing the steel strip after pickling.

[0089] The absorption tower 200 has a furnace gas inlet and an absorption liquid inlet, wherein the furnace gas inlet is used to introduce furnace gas, and the absorption liquid inlet is connected to the interception port to absorb the furnace gas with the interception liquid to obtain regenerated acid. The furnace gas includes HCl gas.

[0090] The cation bed 300, the anion bed 400 and the mixed bed 500 are connected in sequence, and the cation bed 300 is connected with the filtration port, so as to process the filtrate in sequence through the cation bed 300, the anion bed 400 and the mixed bed 500 to obtain desalted water.

[0091] The recycling device for acid-containing washing water is used to implement the recycling method for acid-containing washing water, and therefore has the beneficial effects corresponding to the recycling method for acid-containing washing water, which will not be described in detail.

[0092] In some embodiments, see Figure 1 and Figure 2 , also includes:

[0093] The acid mist washing tower 700 has an acid mist inlet, a primary washing component 710 and a secondary washing component 720 , wherein the secondary washing component 720 is located above the first washing component 710 .

[0094] The primary washing tank 800 circulates with the primary washing assembly 710 to absorb the chloride ions in the acid mist to form a primary washing liquid. The primary washing tank 800 continuously introduces desalted water to replace the primary washing liquid, and the replaced primary washing liquid forms the acid-containing washing water.

[0095] The secondary washing tank 900 circulates with the secondary washing assembly 720 to absorb the chloride ions in the acid mist to form a secondary washing liquid. The secondary washing tank 900 continuously introduces desalted water to replace the secondary washing liquid, and the replaced secondary washing liquid forms the acid-containing washing water.

[0096] This method allows the desalted water to continuously replace the acid mist washing liquid during the acid mist washing process, so that the acid mist washing liquid is at a low free acidity, thereby ensuring the effect of the acid mist washing and further ensuring that the acid mist meets the environmental protection standards. Instead of the acid mist washing liquid being discharged only when the free acidity reaches 5g / L during the acid mist washing process, the acid mist washing liquid often has a reduced ability to absorb and wash the free acid in the acid mist when the free acidity reaches 5g / L.

[0097] In some embodiments, it also includes:

[0098] The multi-stage pickling mechanism 610 has a pre-desiliconization component. The multi-stage pickling mechanism 610 is used to perform multi-stage pickling on the strip steel with the regenerated acid to obtain a post-pickling liquid. The multi-stage pickling process includes a pre-desiliconization treatment.

[0099] The sequentially arranged leaching tower 620, reaction tank 630, sedimentation tank 640, heat exchanger 650 and roasting furnace 660 are used to heat the pickling liquid in sequence, leaching scrap steel, adjusting the pH of the leached solution to 3.5-4.4, separating and precipitating to obtain treatment acid, concentrating the treatment acid, and then roasting to obtain furnace gas, wherein the treatment acid is ferrous chloride solution.

[0100] The recycling device of the acid-containing washing water has a simple structure, realizes efficient acid washing, and reduces the loss of chlorine. In the above technical scheme of the present invention, the above is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for recycling acid-containing washing water, characterized in that: The following steps are involved: The acid-containing washing water is subjected to reverse osmosis to obtain a filtrate and a retentate; wherein the retentate includes chloride ions, silicate ions and metal ions on the surface of the steel strip retained in the reverse osmosis process; the acid-containing washing water includes acid mist washing liquid and / or rinsing water, and the rinsing water is the rinsing water after the steel strip is pickled; The retentate absorbs the furnace gas to obtain regenerated acid; the furnace gas includes HCl gas; The filtrate is treated in sequence by a cation bed, anion bed and mixed bed to obtain desalted water.

2. The method for recycling acid-containing washing water according to claim 1, characterized in that: In the step of performing reverse osmosis on the acid-containing washing water, the chloride ion removal rate is ≥98%, and the conductivity of the produced water is ≤30 microSiemens / cm.

3. The method for recycling acid-containing washing water according to claim 2, characterized in that: The concentration ratio of the acid-containing washing water is 2 to 3 times.

4. The method for recycling acid-containing washing water according to claim 2, characterized in that: Also includes: The reverse osmosis membrane is cleaned with membrane tube cleaning fluid, and the waste liquid generated by the cleaning is discharged into the cold rolling wastewater treatment station for treatment.

5. The method for recycling acid-containing washing water according to claim 1, characterized in that: The step of using the retentate to absorb the furnace gas to obtain the regenerated acid comprises: The furnace gas is cooled, and the retentate is absorbed by the cooled furnace gas to obtain the regenerated acid.

6. The method for recycling acid-containing washing water according to claim 1, characterized in that: Also includes: The regenerated acid is used to perform multi-stage pickling on the strip steel to obtain a pickling liquid; wherein the multi-stage pickling process includes a pre-desiliconization treatment; The pickled solution is sequentially heated, the scrap steel is leached, the pH of the leached solution is adjusted to 3.5-4.4, and then the treated acid is obtained by precipitation and separation, wherein the treated acid is a ferrous chloride solution; The treated acid is concentrated by a heat exchange mechanism and then enters a roasting furnace to obtain furnace gas.

7. The method for recycling acid-containing washing water according to any one of claims 1 to 6, characterized in that: Also includes: The desalted water continuously replaces the acid mist washing liquid, and the replaced acid mist washing liquid forms the acid-containing washing water, wherein the acid mist washing liquid is a washing liquid formed by the desalted water absorbing chloride ions of the acid mist.

8. A recycling device for acid-containing washing water, characterized in that: include: A reverse osmosis component having a reverse osmosis membrane, a filter port and a retentate port; Used to reverse osmosis the acid-containing washing water to obtain a filtrate and a retentate; wherein the retentate includes chloride ions, silicate ions and metal ions on the surface of the steel strip retained during the reverse osmosis process; the acid-containing washing water includes acid mist washing liquid and / or rinsing water, and the rinsing water is the water used for rinsing the steel strip after pickling; An absorption tower having a furnace gas inlet and an absorption liquid inlet, wherein the furnace gas inlet is used to introduce furnace gas, and the absorption liquid inlet is connected to the interception port to continuously circulate the interception liquid to absorb the furnace gas to obtain regenerated acid; the furnace gas includes HCl gas; A cation bed, anion bed and mixed bed are connected in sequence, and the cation bed is connected to the filtration port, so as to process the filtrate in sequence through the cation bed, anion bed and mixed bed to obtain desalted water.

9. The recycling device according to claim 8, characterized in that: Also includes: An acid mist washing tower, comprising an acid mist inlet, a primary washing component and a secondary washing component, wherein the secondary washing component is located above the first washing component; A primary washing tank circulates with the primary washing component to absorb chloride ions in the acid mist to form a primary washing liquid; the primary washing tank continuously introduces desalted water to replace the primary washing liquid, and the replaced primary washing liquid forms the acid-containing washing water; A secondary washing tank circulates with the secondary washing component to absorb chloride ions in the acid mist to form a secondary washing liquid; Desalted water is continuously introduced into the secondary washing tank to replace the secondary washing liquid, and the replaced secondary washing liquid forms the acid-containing washing water.

10. The recycling device according to claim 8, characterized in that: Also includes: A multi-stage pickling mechanism, having a pre-desiliconization component; the multi-stage pickling mechanism is used to carry out multi-stage pickling of the strip steel with the regenerated acid to obtain a post-pickling liquid; wherein the multi-stage pickling process includes a pre-desiliconization treatment; The sequentially arranged leaching tower, reaction tank, sedimentation tank, heat exchanger and roasting furnace are used to heat the pickling solution in sequence, leaching scrap steel, adjusting the pH of the leached solution to 3.5-4.4, precipitating and separating to obtain treatment acid, concentrating the treatment acid, and then roasting to obtain furnace gas, wherein the treatment acid is ferrous chloride solution.

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