CN113860597A

CN113860597A - High-salinity wastewater resource recovery method and system

Info

Publication number: CN113860597A
Application number: CN202010614339.6A
Authority: CN
Inventors: 杨本涛; 廖继勇; 康建刚; 魏进超; 何凯琳; 戴波
Original assignee: Zhongye Changtian International Engineering Co Ltd
Current assignee: Zhongye Changtian International Engineering Co Ltd
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2021-12-31
Anticipated expiration: 2040-06-30
Also published as: CN113860597B

Abstract

A resource recovery method of high-salinity wastewater comprises the following steps: 1) adsorbing fluorine ions and chloride ions in the high-salinity wastewater onto an anode adsorption rod in an electric adsorption mode, leaving sulfate radical-containing miscellaneous salt wastewater mainly containing sulfate radicals, and desorbing the anode adsorption rod to obtain the fluorine-chlorine wastewater; 2) adding chlorine into the fluorine-chlorine wastewater for treatment, increasing the concentration of chloride ions in the fluorine-chlorine wastewater until the chloride ions are supersaturated, crystallizing and separating out the fluoride ions and the chloride ions to obtain fluorine-chlorine mixture crystals, and remaining saturated chlorine-containing solution; 3) crystallizing the saturated chlorine-containing solution to obtain chloride crystal salt; 4) dissolving the fluorine-chlorine mixture for crystallization to obtain a fluorine-chlorine-containing mixed solution, dissolving and adding fluoride for multiple times, and separating to obtain fluoride crystals. The technical scheme that this application provided can reduce the input of extra precipitant, simplifies process flow, and the effect of fluorine chlorine separation to high salt waste water can very big improvement.

Description

High-salinity wastewater resource recovery method and system

Technical Field

The invention relates to a high-salinity wastewater recycling method, in particular to a high-salinity wastewater resource recycling method, belonging to the technical field of sintering wastewater treatment; the invention also relates to a high-salinity wastewater resource recovery system.

Background

The high-salinity wastewater generally contains a large amount of fluorine, chlorine, sulfate and other compounds, has high concentration, complex components and large discharge amount, seriously influences the safety and the product quality of the industrial production process, and simultaneously can generate high toxic risk to the ecological environment.

Aiming at the treatment of high-salinity wastewater, if an evaporation/concentration crystallization method is simply adopted, only low-value mixed salt can be obtained, the resource utilization cannot be realized, the energy consumption is high, and the production cost is high. The idea of purification and recovery generally adopts a process route of 'defluorination, nanofiltration, freezing crystallization and evaporative crystallization', wherein the defluorination process generally adopts methods such as a precipitation method, an adsorption method, an ion exchange method, an electrodialysis method, chemical flocculation precipitation and the like to convert fluorine into other forms so as to realize the defluorination. The methods have different advantages and disadvantages and use conditions, and have the defects of complex operation, higher investment and low resource utilization rate in general. And the nanofiltration method has the problems of high cost and generation of mixed salt mother liquor. In recent years, the electrochemical enhanced deionization technology is concerned in the fields of seawater desalination and the like, and a feasible technical method is provided for the treatment of industrial high fluorine-chlorine wastewater.

In addition, sodium fluoride/potassium fluoride is an important chemical raw material and is widely used for chemical industry, metallurgy, wood preservative and the like. At present, the main production methods of sodium fluoride/potassium fluoride include a melt leaching method, a neutralization method, a sodium fluosilicate method, an ion exchange method and the like. However, these methods require a higher concentration of fluoride ions, which is generally much higher than the concentration of the actual wastewater containing fluorine, and therefore, the wastewater containing fluorine in the prior art cannot be generally used for preparing and recovering sodium fluoride. Only a few patents and documents report methods for preparing recycled sodium fluoride using fluorine waste water, for example, chinese patent CN201710109272 reports a method for separating fluorine from waste water by adding a calcium-containing precipitant, a magnesium-containing precipitant, a sodium-containing precipitant, and an ammonium-or ammonia-containing precipitant to fluorine-containing waste water. However, the method has the defects of large medicament investment and complicated operation. Further innovation is needed.

Therefore, it is an urgent technical problem to be solved by technical personnel in the field how to provide a resource recycling method for high-salinity wastewater, which can reduce the investment of extra precipitant in the process of treating the high-salinity wastewater, simplify the process flow, and greatly improve the effect of fluorine-chlorine separation on the high-salinity wastewater, thereby being beneficial to recycling valuable substances, namely fluoride and chloride, in the process of treating the high-salinity wastewater and improving the treatment quality of the high-salinity wastewater.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to reduce the investment of extra precipitator, simplify the process flow and greatly improve the fluorine-chlorine separation effect aiming at the high-salinity wastewater in the process of treating the high-salinity wastewater, thereby being beneficial to recovering valuable substances, namely fluoride and chloride in the process of treating the high-salinity wastewater and improving the treatment quality of the high-salinity wastewater. The invention provides a resource recovery method of high-salinity wastewater, which comprises the following steps: 1) separating to obtain fluorine-chlorine wastewater: adsorbing fluorine ions and chloride ions in the high-salinity wastewater onto an anode adsorption rod in an electric adsorption mode, leaving sulfate radical-containing miscellaneous salt wastewater mainly containing sulfate radicals, and desorbing the anode adsorption rod to obtain the fluorine-chlorine wastewater; 2) obtaining a saturated chlorine-containing solution: adding chlorine into the fluorine-chlorine wastewater for treatment, increasing the concentration of chloride ions in the fluorine-chlorine wastewater until the chloride ions are supersaturated, crystallizing and separating out the fluoride ions and the chloride ions to obtain fluorine-chlorine mixture crystals, and remaining saturated chlorine-containing solution; 3) obtaining chloride crystal salt: crystallizing the saturated chlorine-containing solution to obtain chloride crystal salt; 4) separating to obtain fluoride crystals: dissolving the fluorine-chlorine mixture to crystallize to obtain chlorine-containing mixed solution, dissolving and adding fluoride for several times, and separating to obtain fluoride crystal.

According to a first embodiment of the invention, a resource recovery method of high-salinity wastewater is provided:

a resource recovery method of high-salinity wastewater comprises the following steps: 1) separating to obtain fluorine-chlorine wastewater: treating the high-salinity wastewater in an electric adsorption mode, adsorbing fluorine ions and chloride ions in the high-salinity wastewater to an anode adsorption rod of an electric adsorption device, leaving sulfate radical-containing miscellaneous salt wastewater mainly containing sulfate radicals, and desorbing the anode adsorption rod to obtain the fluorine-chlorine wastewater; 2) obtaining a saturated chlorine-containing solution: chlorine is added into the fluorine-chlorine wastewater for treatment, the concentration of chloride ions in the fluorine-chlorine wastewater is increased until the chloride ions are supersaturated, all fluoride ions and part of the chloride ions in the wastewater are crystallized and separated out to obtain fluorine-chlorine mixture crystals, and the liquid phase is a saturated chlorine-containing solution; 3) obtaining chloride crystal salt: crystallizing the saturated chlorine-containing solution obtained in the step 2) to obtain chloride crystal salt; 4) separating to obtain fluoride crystals: dissolving the fluorine-chlorine mixture obtained in the step 2) to obtain chlorine-containing mixed solution, dissolving and adding fluoride for multiple times, and separating to obtain fluoride crystals.

In the invention, fluoride is dissolved and added for a plurality of times to improve the concentration of the fluorine ions in the chlorine-containing mixed solution until the fluorine ions are supersaturated, and the fluorine ions are crystallized and separated out to obtain the fluoride crystals. The specific times of dissolving and the specific times of adding fluoride are that the concentration of fluorine ions in the chlorine-containing mixed solution is over saturated until the fluorine ions are over saturated, and the fluorine ions are crystallized to obtain fluoride crystals.

Preferably, the step 4) of increasing the concentration of the fluorine ions in the mixed solution containing fluorine and chlorine until the fluorine ions are supersaturated specifically comprises the following steps: adding water-soluble fluorine salt into the fluorine-chlorine-containing mixed solution until the added fluorine salt is not dissolved any more.

Preferably, the fluoride salt soluble in water is the fluoride crystal finally obtained in step 4) or an outsourced fluoride.

Preferably, the step 2) of increasing the concentration of the chloride ions in the fluorine-chlorine wastewater until the chlorine ions are supersaturated specifically comprises the following steps: adding water-soluble chlorine salt into the fluorine-chlorine wastewater until the chlorine adding completion condition is met, and then completing the chlorine adding treatment; the chlorination conditions are as follows: the introduced chloride crystal salt is not dissolved; or monitoring the fluorine ion concentration C of the fluorine-chlorine wastewater_F，C_FLess than 0.1 g/L; preferably C_FLess than 0.05 g/L; more preferably C_F＜0.01g/L。

Preferably, the water-soluble chloride salt is the chloride crystalline salt finally obtained in step 3).

Preferably, the water-soluble chloride salt is an externally available chloride.

Preferably, the anode adsorption rod in step 1) is an electrode containing a graphene material. The graphite electrode can be simple or can be an adsorption electrode made of special materials.

Preferably, the voltage applied between the anode and cathode materials in the electro-adsorption in the step 1) is 0.2-3.4V; preferably 0.6-1.2V; when the anode adsorption rod is desorbed, reverse voltage is applied to the anode after electric adsorption, and the reverse voltage is-1.2 to-0.6V.

Preferably, the method further comprises the steps of: 5) crystallizing and separating out fluorine ions in the step 4) to obtain fluoride crystals, wherein the liquid phase is a fluorine-chlorine mixed solution; detecting the concentration C of chloride ions in the high fluorine-chlorine mixed solution finally obtained in the step 4)_Cl(ii) a When C is present_Cl> 80g/L, preferably C_Cl> 95g/L, more preferably C_ClWhen the concentration is more than 100g/L, introducing the high fluorine-chlorine mixed solution into the high-salinity wastewater in the step 1) or the fluorine-chlorine wastewater in the step 2), and conversely, introducing the high fluorine into the high-salinity wastewater in the step 1)And introducing the chlorine mixed solution into the step 4) to be used as a dissolving mother solution.

Preferably, the method further comprises the steps of: 6) separating to obtain sulfate: concentrating the sulfate radical-containing mixed salt wastewater obtained in the step 1) to obtain concentrated sulfate radical-containing mixed salt wastewater, and crystallizing the concentrated sulfate radical-containing mixed salt wastewater to obtain sulfate crystals and mixed salt mother liquor; 7) and introducing the mixed salt mother liquor into the concentrated mixed salt wastewater containing sulfate radicals.

Preferably, in the step 2), the step 4) and the step 6), one or more of centrifugal separation, gravity settling and filtration separation are adopted for solid-liquid separation.

Preferably, the crystallization treatment in step 3) and step 6) is one or more of evaporative crystallization, temperature-reduced crystallization, and freeze-dried crystallization.

Preferably, the high-salt wastewater is wastewater containing sulfate, fluoride and chloride which are easily soluble in water, or a mixture of wastewater containing sulfate, fluoride and chloride which are easily soluble in water.

Preferably, the high-salinity wastewater is one or more of wastewater containing sodium sulfate, sodium fluoride and sodium chloride, wastewater containing potassium sulfate, potassium fluoride and potassium chloride, and wastewater containing ammonium sulfate, ammonium fluoride and ammonium chloride.

Preferably, the sulfate concentration in the high-salt wastewater is greater than the fluoride ion concentration.

Preferably, the sulfate radical concentration is 0.05-100 g/L; the concentration of the fluorinion is 0.05 g/L-15 g/L; the concentration of the chloride ions is 0.01 g/L-150 g/L.

According to a second embodiment of the invention, a high-salinity wastewater resource recycling system is provided:

a resource recovery system for high salinity wastewater using the method of the first embodiment, the system comprising: an electro-adsorption desorption device, a chlorination salt precipitation device, a mixed dissolution precipitation device and a first solution crystallization device; the original high-salinity wastewater pipeline is communicated with a liquid inlet of the electro-adsorption desorption device, and a desorption liquid outlet of the electro-adsorption desorption device is communicated with a liquid inlet of the chlorination salting-out device;

the charging hole of the chlorination salt-separating device is communicated with a chloride source; the liquid outlet of the chlorination salt-separating device is communicated with the liquid inlet of the first solution crystallizing device; a solid outlet of the first solution crystallization device discharges chloride crystal salt; a solid outlet of the chlorination salt precipitation device is communicated with a feed inlet of the mixed dissolution precipitation device; the feed inlet of the mixed dissolution and precipitation device is communicated with a fluoride source; and discharging fluoride crystal salt from a solid outlet of the mixing, dissolving and separating device.

Preferably, the chloride source introduced into the feeding port of the chlorine salting-out device is chloride crystallized salt discharged from the first solution crystallizing device.

Preferably, the fluoride source introduced into the feed inlet of the mixed dissolution and precipitation device is fluoride crystal salt discharged by the mixed dissolution and precipitation device.

Preferably, a liquid outlet of the mixed dissolution and precipitation device passes through a first high-fluorine circulating pipeline and returns to a feed inlet of the mixed dissolution and precipitation device; or the second high fluorine circulating pipeline is introduced into the chlorine salting-out device.

Preferably, a chloride ion concentration sensor is arranged at a liquid outlet of the mixed dissolving and precipitating device.

Preferably, the system further comprises: a solution concentration device and a second solution crystallization device; a mother liquor outlet of the electro-adsorption desorption device is communicated with a liquid inlet of the solution concentration device; the liquid outlet of the solution concentration device is communicated with the liquid inlet of the second solution crystallization device; and a solid outlet of the second solution crystallization device discharges sulfate crystals.

Preferably, the liquid outlet of the second solution crystallization device is connected to the original high-salt waste water pipeline or the second solution crystallization device through a third mixed salt mother liquor circulating pipeline.

In the first embodiment of the application, the high-salinity wastewater is treated by adopting an electric adsorption mode, fluoride ions and chloride ions are adsorbed on an anode adsorption rod, then the anode adsorption rod is desorbed to obtain the fluorine-chlorine wastewater, and the sulfate radical-containing mixed salt wastewater mainly containing sulfate radicals is electrolyzed to be left. And then, adopting a self-induction mode to perform chlorination treatment on the fluorine-chlorine wastewater, and increasing the concentration of chloride ions in the fluorine-chlorine wastewater until the chloride ions are saturated. Due to the homoionic effect, i.e. the higher the concentration of chloride ions in the solution, the lower the solubility of fluoride ions; therefore, fluoride ions can be preferentially separated out, when the concentration of chloride ions in the solution is over-saturated, the fluoride ions are completely separated out, and the chloride ions are partially separated out; the mixture of saturated chlorine-containing solution and fluorine and chlorine is finally crystallized in the step 2). And 3) precipitating from the saturated chlorine-containing solution by adopting a crystallization treatment mode to obtain chloride crystalline salt. And finally, in the step 4), after the fluorine-chlorine mixture is dissolved, carrying out fluoridation treatment, increasing the concentration of fluorine ions in the fluorine-chlorine-containing mixed solution until supersaturation, and preferentially separating out the fluorine ions in a fluoride crystal form according to the same ion effect so as to obtain the fluoride crystal. The application provides a technical scheme, at the in-process of handling high salt waste water, has reduced the input of extra precipitant, easy operation, improvement that can be very big is to the effect of the fluorine chlorine separation of high salt waste water to be favorable to handling the recovery of high salt waste water's in-process to valuable material fluoride, chloride, improve the treatment quality of high salt waste water.

It should be noted that, the preferential separation of sulfate ions and fluorine-chlorine elements by means of electro-adsorption is a distinguishing technical feature of the technical scheme provided by the present application, which is different from the prior art. Compared with the prior art that the fluorine element is preferentially separated, the quality of fluorine-chlorine separation in the later period can be effectively improved.

As shown in FIG. 2, when the concentration of sodium chloride exceeds 240g/L under the influence of the homoionic effect of fluorine and chlorine, the NaF solubility is zero.

It should be further explained that the invention provides a method for self-induced separation of fluorine and chlorine for a separation method provided on the basis of a large amount of researches, and the technical process and the technical principle of the method are briefly described as follows: the property that the chloride can reduce the solubility of the fluoride is ingeniously utilized by utilizing the homoionic effect. The method comprises the following steps of increasing the concentration of chloride ions in the fluorine-chlorine wastewater to saturation by utilizing the solubility difference of fluoride and chloride in water and adding chloride salt, wherein the fluoride is difficult to dissolve in a high-concentration chloride solution, so that the fluoride is precipitated in a crystal form, and only the chloride ions are contained in a liquid phase, so that the solution is a saturated chlorine-containing solution; the saturated chlorine-containing solution is continuously crystallized to obtain chloride crystals with extremely high purity. In actual practice, fluoride is precipitated by addition of chlorine salt, and part of fluoride grows on the surface of chloride, and at this time, the precipitated fluorine-chlorine mixture crystals contain not only fluoride but also chloride. The invention utilizes the same ion effect and skillfully utilizes the property that the chloride can reduce the solubility of the fluoride. The fluoride-chlorine mixture is crystallized and the added fluoride is added into a mixed dissolving tank, and with the increase of cycle times and the added fluoride, when the concentration of the mixed fluoride ions reaches saturation, the fluoride crystals can be directly separated out through solid-liquid separation; the residual solution is recycled, thereby realizing the separation of fluorine and chlorine and the respective recovery of fluoride and chloride crystal salt.

In the first embodiment of the present application, the fluorine salt soluble in water is added to the fluorine-containing chlorine mixed solution in step 4) to increase the concentration of fluorine ions in the solution until supersaturation, i.e., the introduced fluorine salt is not dissolved. In a preferred embodiment, the water-soluble fluoride salt used in this step may be either the fluoride crystal obtained in step 4) or an outsourced fluoride, thereby forming a cycle. When the concentration of the fluorine ions in the fluorine-containing chlorine mixed solution becomes supersaturated, no additional fluoride is used for crystallization.

It should be noted that, actually, step 4) can be divided into two steps: 1. adding water-soluble fluorine salt, and increasing the concentration of fluorine ions in the fluorine-chlorine-containing mixed solution until the concentration of the fluorine ions becomes supersaturated; 2. the mixed crystal salt of fluorine and chlorine obtained in the previous step is dissolved, and the mixed solution of fluoride crystal and high fluorine and chlorine can be obtained by solid-liquid separation because the fluorine salt is not dissolved.

In a first embodiment of the present application, the concentration of chloride ions in the wastewater of fluorine and chlorine is increased in step 2) by adding a water-soluble chloride salt to the wastewater of fluorine and chlorine. The same ion effect between fluorine and chlorine ions is utilized, namely, the higher the concentration of chlorine ions in the same solution, the lower the solubility of fluorine ions. That is, when the concentration of chloride ions in the solution is increased, fluoride ions are preferentially precipitated out of the solution to obtain fluoride crystals; and (3) continuing to increase the concentration of the chloride ions in the solution until the chloride ions are supersaturated, so that all the fluoride ions in the fluorine-chlorine wastewater are separated out in a crystalline form, and part of chloride crystalline salt is separated out due to the supersaturation of the chloride ions. Thereby obtaining a saturated chlorine-containing solution. Directly crystallizing the saturated chlorine-containing solution to obtain chloride crystal salt. In the process of adding the water-soluble chlorine salt, when judging that the chlorine salt in the added solution is not dissolved or the fluorine ion concentration is less than a certain value, judging that the chlorination is finished. In a preferred embodiment, the chloride salt added in step 2) may be the chloride crystal salt finally obtained in step 3 or an externally purchased chloride. With the process, only part of chloride crystalline salt in the step 3) needs to be added.

In a first embodiment of the present application, a method for selectively electro-adsorbing halogen ions in wastewater of complex salt type is disclosed in the prior art document (application No. 201910616599.4), and the technical content thereof relates to disclosing the electro-adsorption mode of the present application. Namely, the anode adsorption rod in the step 1) is an electrode containing a graphene material. The graphite electrode can be simple or can be an adsorption electrode made of special materials. Meanwhile, the voltage applied between the anode material and the cathode material in the electro-adsorption in the step 1) is 0.2-3.4V; preferably 0.6-1.2V; when the anode adsorption rod is desorbed, reverse voltage is applied to the anode after electric adsorption, and the reverse voltage is-1.2 to-0.6V.

In the first embodiment of the present application, since the crystals of the mixture of fluorine and chlorine obtained in step 2) contain chloride ions, the concentration C of the chloride ions in the high fluorine-chlorine mixed solution during the circulation of step 4) is_ClThe concentration of the chlorine ions increases, and the higher the concentration of the chlorine ions, the lower the solubility of the fluorine ions, that is, the increasing concentration of the chlorine ions promotes the precipitation of the fluorine ions in the form of crystals, due to the homoionic effect. But when the chloride ion concentration C is higher_ClWhen the concentration is close to the saturation concentration, the chloride ion may be precipitated in the form of crystals. Therefore, the concentration C of the chloride ions in the high fluorine-chlorine mixed solution finally obtained in the step 4) needs to be monitored in real time through the step 5)_ClWhen C is present_Cl> 80g/L, preferably C_Cl> 95g/L, more preferably C_ClWhen the concentration is more than 100g/L, the high fluorine-chlorine mixed solution is introduced into the fluorine-chlorine wastewater in the step 2) or the high-salt wastewater in the step 1) to prevent chloride crystal salt from being separated out in the step 4). Meanwhile, when the high fluorine-chlorine mixed solution containing high-concentration chlorine ions is introduced into the fluorine-chlorine wastewater, the process requirement of improving the concentration of the chlorine ions in the solution in the step 2) can be further promoted.

In a first embodiment of the present application, step 6) is carried out by subjecting the sulfate-containing waste brine to a freeze crystallization treatment. Because the solubility of the sodium sulfate is greatly changed along with the temperature, and the solubility of the fluorine chloride is basically unchanged along with the temperature, the crystallization and precipitation of the sodium sulfate can be realized by freezing and crystallizing the mixed salt wastewater containing the sulfate radical and consisting of high-concentration sulfate radical and low-concentration fluorine chloride, the solid is the sodium sulfate by further solid-liquid separation, and the liquid is the mixed salt mother liquor consisting of the fluorine chloride and a small amount of sulfate radical. In a preferred scheme, the mixed salt mother liquor is introduced into the high-salt wastewater through the step 7) to participate in the public welfare process again, so that the loss of substances to be recovered is prevented, and the separation effect of the method is improved.

The temperature of the freezing crystallization treatment is controlled in the range of-10 ℃ to 10 ℃, and T is preferably-5 ℃ to 5 ℃; more preferably T is-5 ℃ to 0 ℃; can accelerate the sucking out of sodium sulfate in the crystallization process and improve the production efficiency.

In the first embodiment of the present application, step 2), step 4) and step 6) all precipitate solids, and the whole scheme involves a solid-liquid separation treatment. The solid-liquid separation mode in the scheme provided by the application comprises but is not limited to one or more modes of centrifugal separation, gravity settling and filtration separation. And the crystallization treatment mode in the step 3) comprises but is not limited to one or more of evaporation crystallization, temperature reduction crystallization and freeze drying crystallization. Different modes are flexibly selected according to the requirements of the production process of the existing equipment.

In a second embodiment of the present application, a high salinity wastewater self-induced separation system comprises: an electro-adsorption desorption device, a chlorination salt precipitation device, a mixed dissolution precipitation device and a first solution crystallization device; and the devices are sequentially assembled into a whole system according to the process requirements. The system separates fluorine-chlorine wastewater from high-salt wastewater through an electro-adsorption desorption device. And then carrying out chlorination treatment on the fluorine-chlorine wastewater by using a chlorination salting-out device, and increasing the concentration of chloride ions in the wastewater to supersaturation so as to obtain a saturated chlorine-containing solution and fluorine-chlorine mixture crystal. The saturated chlorine-containing solution is crystallized through a first solution crystallizing device to obtain chloride crystal salt. And finally dissolving the fluorine-chlorine mixture crystals by using a mixing, dissolving and precipitating device to obtain a fluorine-chlorine-containing mixed solution, adding a fluoride into the fluorine-chlorine-containing mixed solution to ensure that the concentration of fluorine ions in the fluorine-chlorine-containing mixed solution becomes supersaturated, so that fluorine in the fluorine-chlorine-containing mixed solution crystals cannot be dissolved, and separating to obtain fluoride crystals. The technical scheme that this application provided can improve and separate out fluoride crystallization and the efficiency of chloride crystal salt from the fluorine chlorine waste water.

In a second embodiment of the present application, the chloride crystalline salt discharged from the first solution crystallization device is passed to a chlorine salting out device to increase the chloride ion concentration in the wastewater to supersaturation, thereby reducing the amount of additional additives used.

In the second embodiment of the application, the fluoride crystal salt discharged from the mixed dissolution and precipitation device is returned to the mixed dissolution and precipitation device, so that the fluorine ion concentration in the fluorine-containing chlorine mixed solution is increased, and the use amount of additional additives is reduced.

In the second embodiment of the application, according to the value of the chloride ion concentration of the high-fluorine chlorine mixed solution finally discharged from the mixed dissolving and precipitating device, the high-fluorine chlorine mixed solution is introduced back into the mixed dissolving and precipitating device or introduced into a chlorine salting device, so that the use amount of additional additives is reduced.

In a second embodiment of the present application, the high salinity wastewater self-induced separation system further comprises: a solution concentration device and a second solution crystallization device; and concentrating the sulfate radical-containing mixed salt wastewater into concentrated sulfate radical-containing mixed salt wastewater through a solution concentration device, and crystallizing the concentrated sulfate radical-containing mixed salt wastewater through a second solution crystallization device to obtain sulfate crystals.

The second solution crystallization apparatus employs a freeze crystallization process.

It is further noted that in the prior art, the conventional high-salinity wastewater is subjected to fluoride removal and then sulfate and chloride ion separation and crystallization. Because the properties of fluorine and chlorine are relatively close, if the fluorine is not removed firstly, the sulfate radical is separated out, and then the fluorine and chlorine mixed wastewater is obtained. The traditional fluorine-chlorine wastewater evaporation adopts one-step evaporation without effective control, and only mixed crystal salt of fluorine and chlorine can be obtained. Therefore, the invention can also be said to control the conventional evaporation technology, and realizes the separation of fluorine and chlorine by combining the circulating crystallization with the re-dissolution concentration. Adopts the simplest adjustment, and can realize the separation of fluorine and chlorine without special equipment.

Compared with the prior art, the invention has the following beneficial effects:

1. the application provides a technical scheme can utilize the mode of electrosorption to be preferred from the high salt waste water, separates out sulfate radical waste water and fluorine chlorine waste water, lays a good foundation for the processing of follow, has improved the accuracy and the speed of whole fluorine chlorine sulphur separation, compares in the mode of receiving to strain simultaneously and can greatly reduce investment cost

2. According to the technical scheme provided by the application, the process control is simple, and the concentration of the chlorine element and the fluorine element can be quickly controlled by only detecting the concentration of the chlorine element and the fluorine element, so that fluoride crystals and chloride crystal salts can be obtained;

3. according to the technical scheme, the conventional treatment mode is utilized, the wastewater is treated in the created method, and the initial investment cost of high-salinity wastewater treatment enterprises can be reduced.

4. The application provides a technical scheme, the in-process, the material that mainly utilizes self technology link to produce handles waste water, reduces extra additive demand to reduce the consumptive material cost among the high salt waste water treatment process.

Drawings

FIG. 1 is a flow chart of a resource recovery method of high-salinity wastewater in the technical scheme of the invention;

FIG. 2 is a curve showing the variation of F ion concentration in a saturated NaF solution with the addition of NaCl;

FIG. 3 is a structural flow chart of a high-salinity wastewater resource recovery system in the technical scheme of the invention.

Reference numerals:

1: an electro-adsorption desorption device; 2: a chlorine salting-out device; 3: a mixing, dissolving and separating device; 4: a first solution crystallization device; 5: a solution concentration device; 6: a second solution crystallization device;

l0: an original high-salinity wastewater pipeline; l1: a first high fluorine recycle line; l2: a second high fluorine recycle line; l3: a third mixed salt mother liquor circulating pipeline.

Detailed Description

Preferably, the fluoride salt soluble in water is the fluoride crystal finally obtained in step 4).

Preferably, the water-soluble fluoride salt is an externally available fluoride.

Preferably, the anode adsorption rod in step 1) contains an electrode made of graphene material.

Preferably, the method further comprises the steps of: 5) crystallizing and separating out fluorine ions in the step 4) to obtain fluoride crystals, wherein a liquid phase is a fluorine mixed solution; detecting the concentration C of chloride ions in the high fluorine-chlorine mixed solution finally obtained in the step 4)_Cl(ii) a When C is present_Cl> 80g/L, preferably C_Cl> 95g/L, more preferably C_ClWhen the concentration is more than 100g/L, introducing the high-fluorine-chlorine mixed solution into the high-salt wastewater in the step 1) or the fluorine-chlorine wastewater in the step 2), and conversely, introducing the high-fluorine-chlorine mixed solution into the step 4) to be used as a dissolving mother solution.

a resource recovery system for high salinity wastewater using the method of the first embodiment, the system comprising: an electro-adsorption desorption device 1, a chlorination salt precipitation device 2, a mixed dissolution precipitation device 3 and a first solution crystallization device 4; the original high-salinity wastewater pipeline L0 is communicated with a liquid inlet of the electro-adsorption desorption device 1, and a desorption liquid outlet of the electro-adsorption desorption device 1 is communicated with a liquid inlet of the chlorination salting-out device 2;

the charging hole of the chlorination salting-out device 2 is communicated with a chloride source; the liquid outlet of the chlorination salt-separating device 2 is communicated with the liquid inlet of the first solution crystallizing device 4; a solid outlet of the first solution crystallization device 4 discharges chloride crystal salt; a solid outlet of the chlorination salt precipitation device 2 is communicated with a feed inlet of the mixed dissolution precipitation device 3; the feed inlet of the mixed dissolution and precipitation device 3 is communicated with a fluoride source; and a solid outlet of the mixing, dissolving and precipitating device 3 discharges fluoride crystal salt.

Preferably, the chloride source introduced into the charging port of the chlorine salting-out device 2 is chloride crystal salt discharged from the first solution crystallizing device 4.

Preferably, the fluoride source introduced into the feed port of the mixed solution deposition apparatus 3 is a fluoride crystal salt discharged from the mixed solution deposition apparatus 3.

Preferably, the liquid outlet of the mixed solution separation device 3 is connected with the feed inlet of the mixed solution separation device 3 through a first high-fluorine circulating pipeline L1; or the second high fluorine circulating pipeline L2 is introduced into the chlorine salting-out device 2.

Preferably, a chloride ion concentration sensor is arranged at the liquid outlet of the mixed dissolution and precipitation device 3.

Preferably, the system further comprises: a solution concentration device 5 and a second solution crystallization device 6; a mother liquor outlet of the electro-adsorption desorption device 1 is communicated with a liquid inlet of the solution concentration device 5; the liquid outlet of the solution concentration device 5 is communicated with the liquid inlet of the second solution crystallization device 6; the solid outlet of the second solution crystallizing device 6 discharges sulfate crystals.

Preferably, the liquid outlet of the second solution crystallization device 6 is connected to the original high-salt wastewater pipeline L0 or the second solution crystallization device 6 through a third mixed salt mother liquor circulating pipeline L3.

Example 1

Example 2

Example 1 is repeated except that the concentration of the fluoride ions in the mixed solution containing fluorine and chlorine in the step 4) is increased until the supersaturation of the fluoride ions is specifically: adding water-soluble fluorine salt into the fluorine-chlorine-containing mixed solution until the added fluorine salt is not dissolved any more. The fluorine salt soluble in water is the fluoride crystal finally obtained in the step 4).

Example 3

Example 2 was repeated except that the concentration of chloride ions in the chlorofluoro-waste water was increased in step 2) until the supersaturation of chloride ions was specified as: adding water-soluble chlorine salt into the fluorine-chlorine wastewater until the chlorine adding completion condition is met, and then completing the chlorine adding treatment; the chlorination conditions are as follows: the introduced chloride crystal salt is not dissolved; or monitoring the fluorine ion concentration C of the fluorine-chlorine wastewater_F，C_FIs less than 0.01 g/L. The chloride salt soluble in water is the chloride crystalline salt finally obtained in the step 3).

Example 4

Example 3 was repeated except that the anode was adsorbing an electrode of attapulgite ink in step 1).

Example 5

Repeating the embodiment 4, except that the voltage applied between the anode and cathode materials in the electro-adsorption in the step 1) is 0.2-3.4V; preferably 0.6-1.2V; when the anode adsorption rod is desorbed, reverse voltage is applied to the anode after electric adsorption, and the reverse voltage is-1.2 to-0.6V.

Example 6

Example 6 is repeated, except that the method further comprises the steps of: 5) crystallizing and separating out fluorine ions in the step 4) to obtain fluoride crystals, wherein the liquid phase is a fluorine-chlorine mixed solution; detecting the concentration C of chloride ions in the high fluorine-chlorine mixed solution finally obtained in the step 4)_Cl(ii) a When C is present_ClWhen the concentration is more than 80g/L, the high-chlorine fluorine mixed solution is introduced into the high-salt wastewater in the step 1) or the fluorine-chlorine wastewater in the step 2), and conversely, the high-fluorine-chlorine mixed solution is introduced into the step 4) to be used as a dissolving mother solution.

Example 7

Example 6 is repeated, except that the method further comprises the steps of: 6) separating to obtain sulfate: concentrating the sulfate radical-containing mixed salt wastewater obtained in the step 1) to obtain concentrated sulfate radical-containing mixed salt wastewater, and crystallizing the concentrated sulfate radical-containing mixed salt wastewater to obtain sulfate crystals and mixed salt mother liquor; 7) and introducing the mixed salt mother liquor into the concentrated mixed salt wastewater containing sulfate radicals.

Example 8

Example 7 was repeated except that the solid-liquid separation was carried out by gravity settling in step 2), step 4) and step 6). The crystallization treatment in step 3) and step 6) is freeze-drying crystallization.

Example 9

Example 8 is repeated except that the high-salt wastewater is wastewater containing sulfate, fluoride and chloride which are easily soluble in water, or a mixture of wastewater containing sulfate which is easily soluble in water, wastewater containing fluoride which is easily soluble in water and wastewater containing chloride which is easily soluble in water.

Example 10

Example 9 was repeated except that the high-salinity wastewater was a mixture of wastewater containing sodium sulfate, sodium fluoride and sodium chloride, wastewater containing potassium sulfate, potassium fluoride and potassium chloride, and wastewater containing ammonium sulfate, ammonium fluoride and ammonium chloride.

Example 11

Example 10 was repeated except that the sulfate concentration in the high-salt wastewater was greater than the fluoride ion concentration.

Example 12

Example 11 was repeated except that the sulfate group concentration was 0.05 to 100 g/L; the concentration of the fluorinion is 0.05 g/L-15 g/L; the concentration of the chloride ions is 0.01 g/L-150 g/L.

Example 13

A resource recovery system for high salinity wastewater using the method of the first embodiment, the system comprising: an electro-adsorption desorption device 1, a chlorination salt precipitation device 2, a mixed dissolution precipitation device 3 and a first solution crystallization device 4; the original high-salinity wastewater pipeline L0 is communicated with a liquid inlet of the electro-adsorption desorption device 1, and a desorption liquid outlet of the electro-adsorption desorption device 1 is communicated with a liquid inlet of the chlorination salting-out device 2; the charging hole of the chlorination salting-out device 2 is communicated with a chloride source; the liquid outlet of the chlorination salt-separating device 2 is communicated with the liquid inlet of the first solution crystallizing device 4; a solid outlet of the first solution crystallization device 4 discharges chloride crystal salt; a solid outlet of the chlorination salt precipitation device 2 is communicated with a feed inlet of the mixed dissolution precipitation device 3; the feed inlet of the mixed dissolution and precipitation device 3 is communicated with a fluoride source; and a solid outlet of the mixing, dissolving and precipitating device 3 discharges fluoride crystal salt.

Example 14

Example 13 was repeated except that the chloride source introduced through the inlet of the chlorating salt apparatus 2 was the chloride crystal salt discharged from the first solution crystallization apparatus 4.

Example 15

Example 14 was repeated except that the fluoride source introduced through the feed port of the mixed solution deposition apparatus 3 was the fluoride crystal salt discharged from the mixed solution deposition apparatus 3.

Example 16

Example 15 was repeated except that the liquid outlet of the mixed solution precipitation device 3 was fed back to the feed inlet of the mixed solution precipitation device 3 through the first high-fluorine circulation line L1; or the second high fluorine circulating pipeline L2 is introduced into the chlorine salting-out device 2. A chloride ion concentration sensor is arranged at the liquid outlet of the mixed dissolution and precipitation device 3.

Example 17

Example 16 is repeated except that the system further comprises: a solution concentration device 5 and a second solution crystallization device 6; a mother liquor outlet of the electro-adsorption desorption device 1 is communicated with a liquid inlet of the solution concentration device 5; the liquid outlet of the solution concentration device 5 is communicated with the liquid inlet of the second solution crystallization device 6; the solid outlet of the second solution crystallizing device 6 discharges sulfate crystals.

Example 18

Example 17 was repeated except that the liquid outlet of the second solution crystallization device 6 was connected to the original high-salt wastewater line L0 or the second solution crystallization device 6 through a third mixed salt mother liquor circulation line L3.

Experiment 1

Experiments are carried out according to the resource recycling method of the high-salinity wastewater provided by the application. The experiment was started after the concentrations of chloride, fluoride and sulfate ions in the high-salinity wastewater obtained in the process were determined. Wherein the high fluorine-chlorine mixed solution in the step 4) is the measured value after the second circulation.

Claims

1. A resource recovery method of high-salinity wastewater is characterized by comprising the following steps:

1) separating to obtain fluorine-chlorine wastewater: treating the high-salinity wastewater in an electric adsorption mode, adsorbing fluorine ions and chloride ions in the high-salinity wastewater to an anode adsorption rod of an electric adsorption device, leaving sulfate radical-containing miscellaneous salt wastewater mainly containing sulfate radicals, and desorbing the anode adsorption rod to obtain the fluorine-chlorine wastewater;

2) obtaining a saturated chlorine-containing solution: chlorine is added into the fluorine-chlorine wastewater for treatment, the concentration of chloride ions in the fluorine-chlorine wastewater is increased until the chloride ions are supersaturated, all fluoride ions and part of the chloride ions in the wastewater are crystallized and separated out to obtain fluorine-chlorine mixture crystals, and the liquid phase is a saturated chlorine-containing solution;

3) obtaining chloride crystal salt: crystallizing the saturated chlorine-containing solution obtained in the step 2) to obtain chloride crystal salt;

4) separating to obtain fluoride crystals: dissolving the fluorine-chlorine mixture obtained in the step 2) to obtain chlorine-containing mixed solution, dissolving and adding fluoride for multiple times, and separating to obtain fluoride crystals.

2. The high-salinity wastewater resource recovery method according to claim 1, characterized in that the step 4) of increasing the concentration of the fluoride ions in the mixed solution containing fluorine and chlorine until the supersaturation of the fluoride ions is specifically: adding water-soluble fluorine salt into the fluorine-chlorine-containing mixed solution until the added fluorine salt is not dissolved any more; preferably, the fluoride salt soluble in water is the fluoride crystal finally obtained in step 4) or an outsourced fluoride.

3. The resource recovery method of the high-salinity wastewater according to claim 1 or 2, characterized in that the step 2) of increasing the concentration of the chloride ions in the chlorofluoro wastewater until the supersaturation of the chloride ions is specifically: adding water-soluble chlorine salt into the fluorine-chlorine wastewater until the chlorine adding completion condition is met, and then completing the chlorine adding treatment; the chlorination conditions are as follows: the introduced chloride crystal salt is not dissolved; or monitoring the fluorine ion concentration C of the fluorine-chlorine wastewater_F，C_FLess than 0.1 g/L; preferably C_FLess than 0.05 g/L; more preferably C_FLess than 0.01 g/L; preferably, the water-soluble chloride salt is the chloride crystalline salt finally obtained in step 3).

4. The method for fractional separation, crystallization, recovery and recycling of high-salinity wastewater according to any one of claims 1 to 3, characterized in that the anode adsorption rod in step 1) can be a simple graphite electrode or an adsorption electrode made of a special material; and/or

In the step 1), the voltage applied between the anode material and the cathode material during electric adsorption is 0.2-3.4V; preferably 0.6-1.2V; when the anode adsorption rod is desorbed, reverse voltage is applied to the anode after electric adsorption, and the reverse voltage is-1.2 to-0.6V.

5. The resource recovery method of the high-salinity wastewater according to any one of claims 1 to 4, characterized by further comprising the following steps:

5) crystallizing and separating out fluorine ions in the step 4) to obtain fluoride crystals, wherein the liquid phase is a fluorine-chlorine mixed solution; detecting the concentration C of chloride ions in the high fluorine-chlorine mixed solution finally obtained in the step 4)_Cl(ii) a When C is present_Cl> 80g/L, preferably C_Cl> 95g/L, more preferably C_ClWhen the concentration is more than 100g/L, introducing the high-fluorine-chlorine mixed solution into the high-salt wastewater in the step 1) or the fluorine-chlorine wastewater in the step 2), and conversely, introducing the high-fluorine-chlorine mixed solution into the step 4) to be used as a dissolving mother solution.

6. The resource recovery method of the high-salinity wastewater according to any one of claims 1 to 5, characterized by further comprising the following steps:

6) separating to obtain sulfate: concentrating the sulfate radical-containing mixed salt wastewater obtained in the step 1) to obtain concentrated sulfate radical-containing mixed salt wastewater, and crystallizing the concentrated sulfate radical-containing mixed salt wastewater to obtain sulfate crystals and mixed salt mother liquor;

7) and introducing the mixed salt mother liquor into the concentrated mixed salt wastewater containing sulfate radicals.

7. The resource recovery method of the high-salinity wastewater according to claim 6, characterized in that one or more of centrifugal separation, gravity settling and filtration separation are adopted for solid-liquid separation in the step 2), the step 4) and the step 6); preferably, the crystallization treatment in step 3) and step 6) is one or more of evaporative crystallization, temperature-reduced crystallization, and freeze-dried crystallization.

8. The method for recycling high-salt wastewater as claimed in any one of claims 1 to 7, wherein the high-salt wastewater is wastewater containing sulfate, fluoride and chloride which are easily soluble in water, or is a mixture of wastewater containing sulfate which is easily soluble in water, wastewater containing fluoride which is easily soluble in water and wastewater containing chloride which is easily soluble in water; preferably, the high-salinity wastewater is one or more of wastewater containing sodium sulfate, sodium fluoride and sodium chloride, wastewater containing potassium sulfate, potassium fluoride and potassium chloride, and wastewater containing ammonium sulfate, ammonium fluoride and ammonium chloride.

9. The high-salinity wastewater resource recovery method according to any one of claims 1 to 8, characterized in that the sulfate concentration in the high-salinity wastewater is greater than the fluoride ion concentration; preferably, the sulfate radical concentration is 0.05-100 g/L; the concentration of the fluorinion is 0.05 g/L-15 g/L; the concentration of the chloride ions is 0.01 g/L-150 g/L.

10. A high salinity wastewater resource recovery system applying the high salinity wastewater resource recovery method according to any one of claims 1 to 9, characterized in that the system comprises: an electro-adsorption desorption device (1), a chlorination salting-out device (2), a mixed dissolution precipitation device (3) and a first solution crystallization device (4); an original high-salinity wastewater pipeline (L0) is communicated with a liquid inlet of the electro-adsorption desorption device (1), and a desorption liquid outlet of the electro-adsorption desorption device (1) is communicated with a liquid inlet of the chlorination salt-separating device (2);

the charging hole of the chlorination salting-out device (2) is communicated with a chloride source; the liquid outlet of the chlorination salting-out device (2) is communicated with the liquid inlet of the first solution crystallizing device (4); a solid outlet of the first solution crystallization device (4) discharges chloride crystalline salt; a solid outlet of the chlorination salt precipitation device (2) is communicated with a feed inlet of the mixing, dissolving and precipitation device (3); the feed inlet of the mixed dissolution and precipitation device (3) is communicated with a fluoride source; and a solid outlet of the mixing, dissolving and precipitating device (3) discharges fluoride crystal salt.

11. The high-salinity wastewater self-induction separation system according to claim 10, wherein the chloride source introduced into the feed inlet of the chlorination salt device (2) is chloride crystallized salt discharged from the first solution crystallization device (4); and/or

The fluoride source introduced into the feed inlet of the mixed dissolution and precipitation device (3) is fluoride crystal salt discharged from the mixed dissolution and precipitation device (3).

12. The high-salinity wastewater self-induced separation system according to claim 11, wherein the liquid outlet of the mixed dissolution and precipitation device (3) is communicated back to the feed inlet of the mixed dissolution and precipitation device (3) through a first high-fluorine circulation pipeline (L1); or the mixture is introduced into the chlorine salting-out device (2) through a second high-fluorine circulating pipeline (L2); preferably, a chloride ion concentration sensor is arranged at a liquid outlet of the mixed dissolution and precipitation device (3).

13. The high salinity wastewater self-induced separation system of claim 12, wherein, the system further comprises: a solution concentration device (5) and a second solution crystallization device (6); a mother liquor outlet of the electro-adsorption desorption device (1) is communicated with a liquid inlet of the solution concentration device (5); the liquid outlet of the solution concentration device (5) is communicated with the liquid inlet of the second solution crystallization device (6); a solid outlet of the second solution crystallization device (6) discharges sulfate crystals; preferably, the liquid outlet of the second solution crystallization device (6) is connected to the original high-salinity wastewater pipeline (L0) or the second solution crystallization device (6) through a third mixed-salt mother liquid circulating pipeline (L3).