CN111530291A - Recovery treatment and working method of electrode liquid of electrodialysis equipment - Google Patents
Recovery treatment and working method of electrode liquid of electrodialysis equipment Download PDFInfo
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Abstract
The invention relates to a method for recovering, treating and operating electrode liquid of electrodialysis equipment, which comprises the following steps: (1) conveying electrode liquid with magnesium ion content exceeding a technological requirement value from a replacement mechanism to a treatment mechanism, (2) adding a medicament into the treatment mechanism to enable magnesium ions to form precipitates to obtain electrode liquid slurry, (3) conveying the electrode liquid slurry to a filter pressing mechanism to obtain a first clear liquid, (4) filtering again to obtain a second clear liquid, (5) performing acid regulation treatment to obtain a neutralization supplementary liquid, (6) adding a second acid regulation medicament to obtain electrode liquid, and enabling the electrode liquid to circularly work between the replacement mechanism and an electrodialysis device. The method of the invention obviously reduces the content of magnesium ions in the electrode solution through the specific electrode solution recovery treatment step, so that the treated electrode solution can be recycled, thereby reducing the production cost.
Description
Technical Field
The invention relates to the processing field of separating salt lake brine with high magnesium-lithium ratio by using electrodialysis equipment, in particular to a recovery treatment and working method of electrode liquid of the electrodialysis equipment.
Background
In the processing process of separating the salt lake brine with high magnesium-lithium ratio by using the electrodialysis equipment, the electrodialysis equipment forms the directional migration of ions by utilizing the selective permeability of the ion exchange membrane under the action of a direct current electric field, thereby achieving the magnesium-lithium separation effect. The electrode liquid in the electrodialysis device is a medium for providing current transfer, and the electrode liquid circulates between the positive stage and the negative stage of the electrodialysis device so as to protect the operation safety of core equipment. During operation of the electrodialysis apparatus, a large number of hydroxide ions are generated in the electrode liquid as a result of water dissociation. In addition, as the operation time of the electrodialysis device is prolonged, the content of magnesium ions in the electrode liquid is increased. Magnesium ions combine with hydroxyl ions to produce magnesium hydroxide, which precipitates and adheres to the polar film, resulting in an increase in the resistance of the polar film and a decrease in the current, thereby causing ignition of the polar film.
In order to avoid the situation, when the concentration of magnesium ions in the electrode solution reaches 1.0g/l, the newly prepared electrode solution is used for replacing the electrode solution with the excessively high concentration of magnesium ions, so that the safe and stable operation of equipment is protected. The displaced electrode liquid is generally discharged to a waste tank in its entirety.
If the electrode solution is replaced frequently, the raw material cost is too high. Therefore, there is a need for a method for recycling the electrode solution to reduce the raw material cost and thus the production cost.
Disclosure of Invention
Technical problem
The invention aims to solve the technical problems and provides a method for recycling and operating electrode liquid of an electrodialysis device, which can effectively reduce magnesium ions in the electrode liquid and enable the magnesium ion content in the electrode liquid after treatment to meet the production requirements of the electrodialysis device, thereby recycling the electrode liquid and saving the cost of raw materials. The method is a key technology for recovering and treating the electrode liquid of the electrodialysis equipment.
Technical scheme
In one aspect, the present invention relates to a method for the recovery treatment and operation of an electrode liquid of an electrodialysis plant, comprising the steps of:
(1) the electrode liquid with the magnesium ion content exceeding the technological requirement value is conveyed from a displacement mechanism in an electrode liquid working system to a processing mechanism in an electrode liquid recovery processing system,
(2) adding a medicament into the treatment mechanism to enable magnesium ions in the electrode liquid to form precipitates to obtain electrode liquid slurry,
(3) conveying the electrode liquid slurry to a filter pressing mechanism, removing precipitates in the electrode liquid slurry through pressure filtration to obtain a first clear liquid,
(4) conveying the first clear liquid to a precise filtering mechanism for secondary filtering to remove particulate impurities to obtain a second clear liquid,
(5) conveying the second clear liquid to a storage mechanism, adding a first acid regulating medicament into the storage mechanism for acid regulation treatment to obtain a neutralization replenishing liquid,
(6) and conveying the neutralization replenishing liquid to the replacement mechanism in the electrode liquid working system, adding a second acid regulating medicament into the replacement mechanism to obtain electrode liquid, and circulating the electrode liquid between the replacement mechanism and the electrodialysis equipment.
In one embodiment of the process of the present invention,
in the step (1), the electrode solution is sodium nitrate solution, the process requirement value is 1.0g/l,
in the step (2), the medicament is solid sodium hydroxide,
in the step (3), the precipitate in the electrode liquid slurry is mainly magnesium hydroxide precipitate,
in the step (5), the first acid regulating agent added into the storage mechanism is nitric acid solution with the concentration of 30 vol%,
in the step (6), the second acid adjusting agent added to the displacement mechanism is a nitric acid solution having a concentration of 30 vol%.
In one embodiment of the process of the present invention,
in the step (3), the pH of the first clear liquid is 10-12,
in the step (5), the pH value of the neutralization supplementary liquid is 6-8,
in the step (6), the pH of the electrode liquid is 1.5-2.
In one embodiment, in step (4), the turbidity of the second clear solution is 0.5 to 1 NTU.
In one embodiment, in step (5), the first souring agent is added from above the storage mechanism.
In one embodiment, in step (6), the magnesium ion content in the electrode liquor conveyed from the displacement mechanism to the electrodialysis apparatus is not more than 1.0 g/l.
In one embodiment of the process of the present invention,
in the step (1), the replacement mechanism is a storage tank, the storage tank comprises a tank body, a pH meter and a liquid level meter,
in the step (2), the processing mechanism is an electrode liquid preparation tank, the electrode liquid preparation tank comprises a tank body, a feeding hopper and a stirring motor,
in the step (3), the filter pressing mechanism is a plate-and-frame filter press,
in the step (4), the precise filtering mechanism is a precise safety filter,
in step (5), the storage mechanism is a storage tank, the storage tank comprises a tank body and a liquid level meter, and in step (6), the electrodialysis device comprises a flow meter.
In one embodiment, steps (1) to (6) are carried out cyclically.
Advantageous effects
The recycling and working method of the electrode liquid of the electrodialysis equipment provided by the invention has the advantages that through the specific electrode liquid recycling treatment step, the magnesium ion content in the electrode liquid before entering the electrodialysis equipment is obviously reduced, and the treated electrode liquid can be recycled. Therefore, the purpose of recycling the electrode solution is achieved, the raw material consumption is saved, and the production cost is reduced.
Drawings
Fig. 1 is a schematic diagram of the dosing and the working flow of an electrode liquid of an electrodialysis apparatus according to the prior art.
Fig. 2 is a schematic view of a recovery process and a work flow of an electrode liquid of an electrodialysis apparatus according to an embodiment of the present invention.
Reference numerals
1000: material preparation and working device for electrode liquid of electrodialysis equipment
1100: electrode solution batching system
110: batching mechanism
130: filtering mechanism
140: storage mechanism
1200: electrode liquid working system
150: replacement mechanism
160: electrodialysis apparatus
10: solid sodium nitrate
11: water preparation
12: nitric acid solution
13: brine feed liquid
14: returning brine
101: sodium nitrate solution
102: filtered liquid
103: supplementary liquid
104: electrode liquid feeding liquid
105: electrode liquid return liquid
106: discharging liquid
2000: recovery processing and working device for electrode liquid of electrodialysis equipment
2100: electrode solution recovery processing system
210: processing mechanism
220: filter pressing mechanism
230: precise filtering mechanism
240: storage mechanism
2200: electrode liquid working system
250: replacement mechanism
260: electrodialysis apparatus
20: solid sodium hydroxide
201: electrode liquid slurry
202 a: first clear liquid
202 b: second clear liquid
203: neutralization supplementary liquid
206: recovery liquid
Detailed Description
The recovery treatment and working method of the electrode liquid of the electrodialysis equipment of the invention are described in detail below with reference to the accompanying drawings.
The terms or words used in the present specification and claims should not be construed restrictively as general or dictionary definitions, and should be construed as meanings and concepts corresponding to technical ideas of the present invention on the basis of the principle that the inventor can appropriately define concepts of the terms to describe the invention in the best possible manner.
1. Proportioning and working process of electrode liquid of electrodialysis equipment in prior art
As shown in fig. 1, the dosing and work flow of the electrode liquid of the electrodialysis apparatus of the prior art is performed by using a dosing and work device 1000 of the electrode liquid of the electrodialysis apparatus, which dosing and work device 1000 of the electrode liquid of the electrodialysis apparatus comprises an electrode liquid dosing system 1100 and an electrode liquid work system 1200.
1.1 dosing procedure for electrode liquid of electrodialysis apparatus
Electrode fluid dosing system 1100 includes dosing mechanism 110, microfiltration mechanism 130, and storage mechanism 140.
The batching mechanism 110 can be a tank that includes a tank body, a stirring motor, and a hopper.
First, a fixed amount of preparation water 11 is added to a tank body as a tank of the dosing mechanism 110 through a water supply facility; meanwhile, quantitatively adding solid sodium nitrate 10 into the tank body through a feeding hopper above the tank body, starting a stirring motor to fully dissolve the solid sodium nitrate to obtain a dissolved sodium nitrate solution 101, wherein the conductivity value of the dissolved sodium nitrate solution can be 45-55 ms/cm. The main content of the solid sodium nitrate 10 may be 98 wt% or more.
And conveying the dissolved sodium nitrate solution 101 from the batching mechanism 110 to a precise filtering mechanism 130, and removing 1 micron-sized micro particles in the sodium nitrate solution to obtain filtered liquid 102. The turbidity of the filtered solution may be between 0.5 and 1 NTU.
The precise filtering mechanism 130 is usually a security filter, such as a precise security filter, which contains 8 filter cartridges and is equipped with a 1 μm filter bag, and is mainly used for filtering 1 micron-sized particles in the electrode solution.
To ensure production capacity, a fixed amount of electrode liquid (i.e., filtered liquid 102) is delivered from the microfiltration mechanism 130 to the storage mechanism 140 as a replenishment liquid 103 for storage, and the replenishment liquid 103 is supplied to the displacement mechanism 150 as needed.
The storage mechanism 140 may typically be a steel-lined glue tank that includes a tank body and a level gauge (e.g., a radar level gauge) for monitoring the level of electrode fluid.
1.2 working procedure of electrode liquid of electrodialysis equipment
The electrode fluid working system 1200 may include a displacement mechanism 150 and an electrodialysis device 160. The displacement mechanism 150 mainly includes a tank (e.g., a glass fiber reinforced plastic tank) including a tank body, a pH meter, and a liquid level meter. The displacement mechanism 150 and the electrodialysis device 160 form a circulation loop. The electrodialysis device 160 is provided with a flow meter.
First, the replenishment liquid 103 from the reservoir mechanism 140 is supplied from above the replacement mechanism 150; at the same time, the automatic acid addition control program was started, and 30 vol% nitric acid solution 12 was introduced from above the displacement mechanism 150 to adjust the pH of the electrode solution. When the pH of the electrode solution reaches the process control requirement (e.g., pH 1-2, preferably 1.5), the automatic acid addition control procedure is stopped.
Then, the electrodialysis device 160 is started, brine feed liquid 13 is conveyed to the inside of the electrodialysis device through a brine conveying pump for separation, and obtained brine return liquid 14 is conveyed to a brine storage tank. Meanwhile, the electrode solution feed liquid 104 is delivered to both sides of the positive electrode and the negative electrode of the electrodialysis device 160 by the electrode solution delivery pump to work, and the electrode solution return liquid 105 after working is delivered back to the displacement mechanism 150.
During operation of the electrodialysis apparatus 160, the electrode liquid in the tank of the displacement mechanism 150 is periodically assayed for magnesium ion content. When the magnesium ion content exceeds 1.0g/l, the electrode liquid is discharged as a discharge liquid 106 from the displacement mechanism 150 to a discharge tank.
Then, the replenishment liquid 103 is transferred to the replacement mechanism 150 through the storage mechanism 140, and the transfer amount of the replenishment liquid 103 is controlled by a level meter, so that the electrode liquid in the replacement mechanism 150 rises to the set liquid level of the storage tank; at the same time, the automatic acid addition control program is started to allow 30 vol% of the nitric acid solution 12 to enter from above the displacement mechanism 150 to adjust the pH of the electrode solution, and when the pH of the electrode solution reaches the process control requirement (for example, pH 1 to 2, preferably 1.5), the automatic acid addition control program is stopped.
When the electrode solution is circulated between the displacement mechanism 150 and the electrodialysis device 160 for a plurality of times, magnesium ions in the brine treated in the electrodialysis device 160 permeate into the electrode solution through the polar membrane, resulting in a magnesium ion content in the electrode solution of more than 1.0 g/l. The electrode liquid is thereby delivered as discharge liquid 106 from the displacement mechanism 150 to the discharge tank via the discharge pump. This results in a loss of electrode liquid. In addition, in order to provide a new electrode liquid, a new replenishment liquid 103 needs to be added to the replacement mechanism 150, which increases the production cost.
When the sodium nitrate solution (electrode liquid) in the storage means 140 is completely transferred to the displacement means 150 and the magnesium ion content in the displacement means 150 exceeds 1.0g/l, the electrodialysis apparatus is stopped according to the production and maintenance requirements.
2. The invention relates to a recycling treatment and a working process of electrode liquid of electrodialysis equipment
In order to improve the use efficiency of the electrode liquid and reduce the production cost, when the magnesium ion content of the electrode liquid in the replacement mechanism exceeds 1.0g/l, the invention improves the batching and the working process of the electrode liquid of the electrodialysis equipment in figure 1 into the recovery treatment and the working process of the electrode liquid of the electrodialysis equipment in the invention by adding processes and equipment, and uses the recovery treatment and the working device 2000 of the electrode liquid of the electrodialysis equipment in figure 2.
Fig. 2 shows a recovery treatment and a work flow of an electrodialysis device electrode liquid according to an embodiment of the present invention, which includes a recovery treatment and work apparatus 2000 using an electrodialysis device electrode liquid, the recovery treatment and work apparatus 2000 of an electrodialysis device electrode liquid including an electrode liquid recovery treatment system 2100 and an electrode liquid work system 2200.
In contrast to the compounding and operation of the electrode liquid for the electrodialysis apparatus of fig. 1, in the recovery treatment and operation of the electrode liquid for the electrodialysis apparatus of fig. 2, the discharge liquid 206 discharged from the displacement mechanism 250 is recycled to the treatment mechanism 210, and a filtration and slag pressing process (which is performed by the filter pressing mechanism 220) is provided between the treatment mechanism 210 and the microfiltration mechanism 230, and a fixed amount of 30 vol% nitric acid solution 12 is replenished to the storage mechanism 240. Otherwise, the flow in fig. 2 corresponds to, i.e. is identical to, the flow in fig. 1.
In practical use, after the work flow of fig. 1 is finished, the work flow of fig. 1 may be modified (including valve change, etc.), so as to obtain the flow of fig. 2.
This will be described in detail with reference to fig. 2.
2.1 recovery treatment Process of electrode liquid for electrodialysis Equipment
The electrode solution recycling system 2100 mainly includes a processing mechanism 210, a filter-pressing mechanism 220, a microfiltration mechanism 230, and a storage mechanism 240.
The processing mechanism 210 corresponds to the dosing mechanism 110 of fig. 1 and may be a tank including a tank body, a stirring motor, and a hopper.
First, the collected liquid 206 from the replacement means 250 is sent to the treatment means 210; meanwhile, solid sodium hydroxide 20 is quantitatively put into the tank body through a feeding hopper above the tank body, and is stirred to be completely reacted with magnesium ions in the discharge liquid 206, so that electrode liquid slurry containing magnesium hydroxide solid is obtained, and the pH value of the electrode liquid slurry is 10-12. The main content of the solid sodium hydroxide 20 was 98 wt%.
Then, the electrode solution slurry 201 enters a filter pressing mechanism 220, and a large amount of precipitates (mainly magnesium hydroxide) in the electrode solution slurry form a filter cake on the surface of the plate frame through filter pressing deslagging, so that a filtered first clear liquid 202a is obtained, wherein the pH value of the filtered first clear liquid is 10-12.
The filter press mechanism 220 may be a plate and frame filter press. The filter cake in the plate frame of the plate-and-frame filter press can be discharged periodically.
Then, the first clear liquid 202a enters a subsequent microfiltration mechanism 230, which is mainly used for filtering 1 micron-sized fine particles in the first clear liquid 202a, and obtaining a second clear liquid 202b with a turbidity of 0.5-1 NTU.
The microfiltration mechanism 230, which corresponds to the microfiltration mechanism 130 of fig. 1, can be a precision cartridge filter.
The second clear liquid 202b is then passed into a storage mechanism 240. The storage mechanism 240, which corresponds to the storage mechanism 140 of fig. 1, may be a steel-lined glue tank, which includes a tank body and a level gauge (e.g., a radar level gauge) for monitoring the level of electrode liquid.
When the second clear liquid 202b is introduced into the storage means 240, a fixed amount of 30 vol% nitric acid solution 12 may be supplemented into the storage means 240 to adjust the pH of the second clear liquid 202b to 6 to 8, preferably 7, thereby obtaining the neutralization replenishment liquid 203. The storage mechanism 240 is mainly used to prepare and store the neutralization solution 203, and supply the neutralization solution 203 to the replacement mechanism 250 when necessary to ensure the production capacity.
2.2 working procedure of electrode liquid for electrodialysis apparatus
The electrode bath working system 2200 includes a displacement mechanism 250 and an electrodialysis device 260.
First, the neutralization replenishment liquid 203 from the reservoir 240 is replenished from above the replacement mechanism 250; at the same time, the automatic acid addition control program is started to allow 30 vol% of the nitric acid solution 12 to enter from above the displacement mechanism 150 to adjust the pH of the electrode solution in the displacement mechanism 250, and when the pH of the electrode solution reaches the process control requirement (for example, pH 1 to 2, preferably 1.5), the automatic acid addition control program is stopped.
Then, the electrodialysis apparatus 260 is started, brine feed liquid 13 is conveyed to the inside of the electrodialysis apparatus for treatment through a brine conveying pump, and obtained brine return liquid 14 is conveyed to a brine storage tank. The electrode solution feed liquid 104 is conveyed to the positive and negative sides of the electrodialysis device 260 by an electrode solution conveying pump to work, and the electrode solution return liquid 105 after the work is conveyed to the replacement mechanism 250.
The electrodialysis apparatus 260 corresponds to the electrodialysis apparatus 160 of fig. 1 and is provided with a flow meter. The displacement mechanism 250 corresponds to the displacement mechanism 150 in fig. 1 and mainly includes a tank (e.g., a glass fiber reinforced plastic tank) including a tank body, a pH meter, and a liquid level meter. The displacement mechanism 250 and the electrodialysis apparatus 260 form a circulation loop.
During operation of the electrodialysis apparatus 260, the electrode liquid in the tank of the displacement mechanism 250 is periodically assayed for magnesium ion content. When the magnesium ion content exceeds 1.0g/l, the electrode liquid is conveyed from the replacement means 250 to the treatment means 210 as the recovered liquid 206.
Then, the neutralization make-up liquid 203 is conveyed to the replacement mechanism 250 through the storage mechanism 240, and the conveying amount of the neutralization make-up liquid 203 is controlled through the liquid level, so that the electrode liquid in the replacement mechanism 250 is raised to the set liquid level of the storage tank; at the same time, the automatic acid addition control program is started, and the nitric acid solution 12 is conveyed to the displacement mechanism 250 by the conveying pump. When the pH of the electrode solution reaches the process control requirement (e.g., pH 1-2, preferably 1.5), the automatic acid addition control procedure is stopped.
In one embodiment, the process pipeline of the electrode liquid recovery processing and working device 2000 of the electrodialysis equipment can be a UPVC pipeline.
In one embodiment, the above-described electrodialysis apparatus electrode liquid recovery treatment and working apparatus 2000 may further include one or more valves, a transfer pump, a pH meter, a liquid level meter, and a flow meter as necessary.
In one embodiment, in the above-mentioned apparatus 2000 for recovering and treating electrode liquid of an electrodialysis apparatus, the nitric acid solution 12 used in the storage means 240 and the replacement means 250 may be supplied from the same or different nitric acid solution storage tanks and transfer pumps as needed.
In one embodiment, the above-mentioned prior art electrodialysis apparatus electrode liquid formulation and work flow is subjected to process modification to obtain the electrodialysis apparatus electrode liquid recovery treatment and work flow of the present invention.
In one embodiment, a sodium nitrate solution is required to be prepared as an electrode solution starting solution at the initial start-up of the electrodialysis apparatus. Specifically, the above-mentioned dosing and work flow of the electrode liquid of the electrodialysis apparatus of the prior art are first started, and the electrode liquid is circulated between the electrodialysis apparatus and the displacement mechanism for many times. When the magnesium ion content of the electrode liquid in the replacement mechanism exceeds the process requirement value, the recovery treatment and the working process of the electrode liquid of the electrodialysis equipment are started.
Examples
Hereinafter, the present invention will be described in detail with reference to examples to specifically describe the present invention. However, the embodiment of the present invention may be modified into various other forms and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention to those of ordinary skill in the art.
The apparatus or materials in the following examples are commercially available from the general market or can be easily prepared by the self, unless otherwise specified.
Comparative example 1
Referring to fig. 1, the dosing and the work flow of the electrode liquid of the electrodialysis apparatus in this comparative example included treatment using an electrode liquid dosing system and an electrode liquid working system.
1. Dosing process using electrode fluid dosing system
First, a preparation water (4 m) from a water supply facility was added to an electrode solution preparation tank (steel-lined glue tank made of Q235-B-lined glue, from Jiangsu Langyuan environmental protection technology Co., Ltd.) as a preparation mechanism3) And solid sodium nitrate (200kg) was added from a hopper above the steel lined glue tank. And starting a stirring motor to stir for 30min to completely dissolve the solid sodium nitrate to obtain a sodium nitrate solution.
The sodium nitrate solution is made to enter a precise cartridge filter (black platinum industrial technology limited, 8 bags, three-layer filter bag with inner filter bag of 1 μm, the removal rate of the three-layer filter bag to the micro particles is 90%, the material is TA8), and 1 micron-sized micro particles in the sodium nitrate solution are removed to obtain the filtered sodium nitrate solution.
The filtered sodium nitrate solution (6 m)3) The liquid is stored in a storage tank (steel lined rubber tank made of Q235-B lined rubber, from Jiangsu Langyuan environmental protection technology Co., Ltd.) as a storage means 140 as a replenishment liquid for being transported to a replacement means described below.
Furthermore, the filtered sodium nitrate solution (6 m) was subsequently delivered from the storage tank3) Thereafter, the above compounding process was repeated to obtain a new supplement (6 m)3)。
2. Working process using electrode liquid working system
First, the electrode solution was transferred (6 m) to an electrode solution tank (from glass fiber reinforced plastics, a material of chemical and chemical apparatus, Inc. in Jiangsu province)3) A replenishment solution from the storage means.
Then, the electrodialysis apparatus (model: ED-X, available from ASTOM of Japan) was started to feed the electrode solution (6 m)3H) entering positive and negative poles of the electrodialysis equipment for circulation, and returning electrode solution to the electrode solution storage tank; simultaneously feeding brine (30 m)3H) entering the electrodialysis equipment for separation, conveying the separated brine return liquid to a brine storage tank,
and sampling and analyzing the electrode solution in the electrode solution storage tank every hour, and checking the magnesium ion content of the electrode solution. When the content of magnesium ions exceeds 1.0g/l, the electrode liquid with high content of magnesium ions is discharged to a discharge tank through a discharge pump on the premise of ensuring the electrode liquid circulation flow required by the operation of the electrodialysis equipment.
The discharge amount of the electrode liquid is controlled by the liquid level. Specifically, the liquid level was lowered to 2/3 of the electrode liquid storage tank, corresponding to a discharge of 1.5m3The effluent of (4); and timely feeding of a new replenishing liquid (1.5 m) from the storage means3) To the set level of the electrode solution tank (specifically, the tank is 1.5m high, and the replenishment level is 1.4m high). And simultaneously starting an automatic acid adding program control program (from an automatic control operation system in Zheda province), so that the nitric acid solution (with the concentration of 30 vol%) enters from the upper part of the electrode solution storage tank, and stopping the automatic acid adding program control program when the pH value of the electrode solution in the electrode solution storage tank reaches 1.5.
The electrode liquid batching system and the electrode liquid working system are connected in series. During the operation of the electrodialysis device, the electrode solution proportioning system intermittently supplies the supplementary solution to meet the operation requirement of the electrode solution working system. And the electrode liquid with the magnesium ion content exceeding the process value in the electrode liquid working system is discharged to a discharge pool through an electrode liquid storage tank serving as a replacement mechanism.
When the sodium nitrate solution in the reservoir as the storage mechanism 140 is entirely transferred to the electrode solution reservoir as the replacement mechanism and the magnesium ion content in the electrode solution reservoir exceeds 1.0g/l, the electrodialysis apparatus is stopped.
Example 1
Referring to fig. 2, the recovery treatment and the work flow of the electrode liquid of the electrodialysis apparatus in the present embodiment include treatment using an electrode liquid recovery treatment system and an electrode liquid working system.
In comparison with the preparation and operation of the electrode liquid for an electrodialysis apparatus of comparative example 1, in the recovery treatment and operation of the electrode liquid for an electrodialysis apparatus of the present embodiment, the recovery liquid 206 discharged from the replacement mechanism 250 is recycled and recovered to the treatment mechanism 210, the filter press mechanism 220 is provided between the treatment mechanism 210 and the microfiltration mechanism 230 to perform the filtration treatment, and a fixed amount of the nitric acid solution 12 is replenished to the storage mechanism 240. Otherwise, the flow in example 2 corresponds to, i.e. is the same as, the flow in example 1.
Specifically, after the flow of comparative example 1 was completed, the flow of comparative example 1 was modified (including valve change and the like) to obtain the flow of example 1.
1. Recovery process using electrode solution recovery processing system
First, the blending process using the electrode solution blending system and the working process using the electrode solution working system in comparative example 1 described above were repeated. After the electrodialysis equipment is circulated for many times, when the magnesium ion content of the electrode liquid in the replacement mechanism exceeds 1.0g/l (the process requirement value), the recovery treatment and working device of the electrode liquid of the electrodialysis equipment in the embodiment is started.
Specifically, the recovered solution (1.5 m) of comparative example 1, in which the magnesium ion content from the electrode solution reservoir as the replacement means exceeded 1.0g/l3) And transferred to a processing means (which is a storage tank corresponding to the electrode solution preparation tank in comparative example 1). After 4 times of discharge and transportation, the accumulated recovery liquid in the treatment mechanism reaches 6m3。
Then, solid sodium hydroxide (12kg) is added from a charging hopper above the treatment mechanism, and a stirring motor is started to stir for 50min, so that the solid sodium hydroxide and magnesium ions in the recovered solution completely react to obtain electrode solution slurry containing a large amount of magnesium hydroxide precipitates.
And (3) conveying the electrode solution slurry which is completely reacted to a plate-and-frame filter press (from Jingjin environmental protection, model: XMY20/630-U) serving as a filter press mechanism through a conveying pump for primary filtration, so that a large amount of magnesium hydroxide is precipitated on the surface of the plate frame to form a filter cake, and obtaining a first filtered clear solution.
And filtering the first clear liquid again. Specifically, the first clear liquid is conveyed to a precise cartridge filter serving as a precise filtering mechanism, and 1 micron-sized micro particles in the first clear liquid are removed to obtain a second clear liquid which is alkaline and has the pH value of 10-12.
Then, the second clear liquid was transferred to a storage tank as a storage mechanism, and a 30 vol% nitric acid solution was passed on the storage tankSquare into a storage tank, wherein the square is based on 1m3The nitric acid solution of the second clear solution was added in an amount of 4L, and the pH of the resulting solution was adjusted to 7 as a neutralization supplement (6 m)3)。
2. Working process using electrode liquid working system
First, a recovered solution (1.5 m) having a magnesium ion content of more than 1.0g/l was fed from the electrode solution reservoir as the displacement mechanism3) After being conveyed to the processing mechanism, the electrode solution is conveyed to the electrode solution storage tank (1.5 m)3) A neutralization replenishment solution from a storage mechanism, and a nitric acid solution (with a concentration of 30 vol%) is added to the electrode solution tank to adjust the pH.
Then, the electrodialysis apparatus was started to feed the electrode solution (6 m)3H) entering positive and negative poles of the electrodialysis equipment for circulation, and returning electrode solution to the electrode solution storage tank; simultaneously feeding brine (30 m)3And h) entering the electrodialysis equipment for separation, and conveying the separated brine return liquid to a brine storage tank.
And sampling and analyzing the electrode solution in the electrode solution storage tank every hour, and checking the magnesium ion content of the electrode solution. When the content of magnesium ions exceeds 1.0g/l, the electrode liquid circulation flow (6 m) required for ensuring the operation of the electrodialysis equipment3H), discharging the electrode solution with high magnesium ion content from the electrode solution storage tank to a storage tank serving as a treatment mechanism by a displacement pump, and repeating the recovery treatment process.
In addition, the discharge amount of the electrode liquid is controlled by the liquid level. Specifically, the liquid level was lowered to 2/3 of the electrode liquid storage tank, corresponding to a discharge of 1.5m3The effluent of (4); then, the neutralization replenishment liquid (1.5 m) was supplied from the reservoir3) Raising the electrode solution in the electrode solution storage tank to a set liquid level (specifically, the storage tank is 1.5m high, and the supplement liquid level is 1.4m high); meanwhile, the automatic acid adding program control program is started to enable the nitric acid solution (with the concentration of 30 vol%) to enter from the upper part of the electrode solution storage tank, and the automatic acid adding program control program is stopped when the pH value of the electrode solution in the electrode solution storage tank reaches 1.5.
The electrode liquid recovery processing system is in circulating connection with the electrode liquid working system. During the operation of the electrodialysis device, the electrode solution recovery treatment system intermittently supplies the supplementary solution to meet the operation requirement of the electrode solution working system. The electrode liquid with the magnesium ion content exceeding 1.0g/l (process value) in the electrode liquid working system is recycled from the electrode liquid storage tank serving as the replacement mechanism to the storage tank serving as the treatment mechanism for recycling treatment again, thereby achieving the purpose of recycling.
Experimental example 1 measurement of magnesium ion content
The recovered solution from the replacement mechanism 250 (corresponding to the effluent solution of comparative example 1) and the neutralization/replenishment solution from the storage mechanism 240 in example 1 were each subjected to measurement of the magnesium ion content by a detection method of complexometric titration.
Specifically, 10ml of each of the recovered solution and the neutralization replenisher in example 1 was taken, 10ml of an ammonia buffer solution was added, 3 to 5 drops of cadmium black T were added, EDTA with a titer of about 1.2 was added to the purple color, the number of volumes of EDTA used was read, and the magnesium ion content in the recovered solution and the neutralized solution was obtained by calculation.
TABLE 1
| Content of magnesium ions (g/l) | |
| Recovery liquid | 1.10 |
| Neutralization supplementary liquid | 0.005 |
As is apparent from Table 1, the magnesium ion content of the recovered solution exceeds the process requirement value of 1.0g/l, the magnesium ion content of the neutralization replenishing solution is obviously reduced, the electrode solution after recovery treatment achieves the purpose of recycling, and the batching cost of the electrode solution is reduced. This is a sufficient evidence that the recovery treatment method of the present invention significantly reduces the magnesium ion content in the recovered liquid (corresponding to the effluent of comparative example 1).
Experimental example 2 comparison of blending cost and recovery processing cost of electrode liquid
At a treatment rate of 500m per 24h3Brine and discharge of 30m3The electrode solution discharge solution was used as a production amount, and the electrode solution compounding cost of comparative example 1 and the electrode solution recovery processing cost of example 1 were calculated.
TABLE 2 cost of electrode solution formulation of comparative example 1 (2019)
| Item | Monovalent (yuan/ton) | Dosage (t) | Cost of liquid preparation (Yuan) |
| Solid sodium nitrate | 2619.469 | 1.2 | 3143.36 |
| |
14 | 30 | 420 |
| Total up to | 3563.36 |
TABLE 3 cost of electrode solution recovery treatment of example 1 (2019)
| Item | Monovalent (yuan/ton) | Dosage (t) | Cost of treatment (Yuan) |
| Nitric acid | 3451.327 | 0.01875 | 64.71 |
| Sodium hydroxide | 2814.15 | 0.165 | 464.33 |
| Total up to | 529.04 |
According to Table 2, the cost of the electrode solution formulation of comparative example 1 was 3563.36 Yuan. According to Table 3, the cost of the electrode solution recovery treatment in example 1 was only 529.04 Yuan. That is, according to the recovery treatment and working method of the electrode liquid of the electrodialysis apparatus of example 1, at least 3000 yuan will be saved per day, which significantly reduces the production cost.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
Claims (8)
1. A method for recovery treatment and operation of an electrode liquid of an electrodialysis device, the method comprising the steps of:
(1) the electrode liquid with the magnesium ion content exceeding the technological requirement value is conveyed from a displacement mechanism in an electrode liquid working system to a processing mechanism in an electrode liquid recovery processing system,
(2) adding a medicament into the treatment mechanism to enable magnesium ions in the electrode liquid to form precipitates to obtain electrode liquid slurry,
(3) conveying the electrode liquid slurry to a filter pressing mechanism, removing precipitates in the electrode liquid slurry through pressure filtration to obtain a first clear liquid,
(4) conveying the first clear liquid to a precise filtering mechanism for secondary filtering to remove particulate impurities to obtain a second clear liquid,
(5) conveying the second clear liquid to a storage mechanism, adding a first acid regulating medicament into the storage mechanism for acid regulation treatment to obtain a neutralization replenishing liquid,
(6) and conveying the neutralization replenishing liquid to the replacement mechanism in the electrode liquid working system, adding a second acid regulating medicament into the replacement mechanism to obtain electrode liquid, and circulating the electrode liquid between the replacement mechanism and the electrodialysis equipment.
2. The method of claim 1, wherein
In the step (1), the electrode solution is sodium nitrate solution, the process requirement value is 1.0g/l,
in the step (2), the medicament is solid sodium hydroxide,
in the step (3), the precipitate in the electrode liquid slurry is mainly magnesium hydroxide precipitate,
in the step (5), the first acid regulating agent added into the storage mechanism is nitric acid solution with the concentration of 30 vol%,
in the step (6), the second acid adjusting agent added to the displacement mechanism is a nitric acid solution having a concentration of 30 vol%.
3. The method of any one of claims 1-2, wherein
In the step (3), the pH of the first clear liquid is 10-12,
in the step (5), the pH value of the neutralization supplementary liquid is 6-8,
in the step (6), the pH of the electrode liquid is 1.5-2.
4. The method according to any one of claims 1-3, wherein in step (4), the turbidity of the second serum is 0.5-1 NTU.
5. The method of claim 1, wherein in step (5), the first acid regulating agent is added from above the storage mechanism.
6. A process according to claim 1, wherein in step (6), the magnesium ion content in the electrode liquor delivered from the displacement means to the electrodialysis apparatus does not exceed 1.0 g/l.
7. The method of claim 1, wherein
In the step (1), the replacement mechanism is a storage tank, the storage tank comprises a tank body, a pH meter and a liquid level meter,
in the step (2), the processing mechanism is an electrode liquid preparation tank, the electrode liquid preparation tank comprises a tank body, a feeding hopper and a stirring motor,
in the step (3), the filter pressing mechanism is a plate-and-frame filter press,
in the step (4), the precise filtering mechanism is a precise safety filter,
in the step (5), the storage mechanism is a storage tank, the storage tank comprises a tank body and a liquid level meter,
in step (6), the electrodialysis apparatus includes a flow meter.
8. The method of claim 1, wherein steps (1) through (6) are performed cyclically.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20030072977A (en) * | 2002-03-07 | 2003-09-19 | 엘지.필립스 엘시디 주식회사 | Method of Ag electroless plating on ITO electrode |
| CN106365183A (en) * | 2016-11-14 | 2017-02-01 | 中国科学院青海盐湖研究所 | Recovery method of electrode discharge solution in high-magnesium solution electrodialysis lithium extraction process |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20030072977A (en) * | 2002-03-07 | 2003-09-19 | 엘지.필립스 엘시디 주식회사 | Method of Ag electroless plating on ITO electrode |
| CN106365183A (en) * | 2016-11-14 | 2017-02-01 | 中国科学院青海盐湖研究所 | Recovery method of electrode discharge solution in high-magnesium solution electrodialysis lithium extraction process |
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