Gradient extraction method of produced water associated resources

Abstract

The invention provides a gradient extraction method of produced water associated resources. According to the produced water associated resource gradient extraction method, a pre-separation step is designed, monovalent ions and divalent ions in produced water are preliminarily separated, bromine extraction, strontium extraction and lithium extraction procedures are organically connected in series or in parallel, the strontium and lithium recovery steps can be synchronously carried out, the technological process is simpler, energy consumption is lower, and the production efficiency is improved. And efficient stepped extraction of bromine, lithium, strontium and other elements with the content reaching a certain abundance and exceeding the comprehensive industrial mining grade in the produced water is comprehensively realized in a complete set.

Description

Technical Field

[0001] This invention belongs to the field of produced water resource utilization technology, and particularly relates to a method for cascade extraction of associated resources from produced water. Background Technology

[0002] In many oilfields, the produced water contains levels of lithium (20-80 mg / L), strontium (500-1000 mg / L), and bromine (100-300 mg / L), exceeding the industrial grade for comprehensive utilization (lithium 25 mg / L, strontium 15 mg / L, bromine 60 mg / L). Based on current produced water volumes and market prices, it is estimated that the extraction of all associated resources could generate billions of yuan in economic value. Currently, the comprehensive utilization of produced water mainly focuses on the extraction of single resources, while other unextracted resources are reinjected with the produced water, resulting in a significant waste of resources.

[0003] Currently, there are few comprehensive methods for the utilization of produced water, and the extraction processes for multiple resources vary significantly depending on the type of resource to be extracted. For example, Chinese patent CN115404348B proposes a method for the comprehensive utilization of brine, using multiple types of adsorbents to adsorb uranium, cesium, and rubidium, and extracting lithium from the adsorption tailings. Another example is Chinese patent application CN114348970A, which proposes a method for the comprehensive utilization of underground brine, proposing a method for the comprehensive extraction of multiple elements such as sodium, calcium, magnesium, bromine, iodine, potassium, and lithium. These methods for the comprehensive utilization of brine are lengthy and complex, often requiring multiple concentrations of the brine, resulting in high energy consumption, and are not suitable for the reinjection treatment requirements of produced water from oil and gas fields. Summary of the Invention

[0004] To address the problems of existing technologies for the comprehensive utilization of associated resources in produced water, such as long process flow, cumbersome technology, and high energy consumption, which are not suitable for the reinjection treatment requirements of produced water in oil and gas fields, the purpose of this invention is to provide a tiered extraction method for associated resources in produced water. Through a simpler process flow and lower energy consumption, this method comprehensively and systematically extracts elements such as bromine, lithium, and strontium in produced water that have reached a certain abundance and exceed the comprehensive industrial extraction grade, so as to minimize the waste of associated resources in produced water.

[0005] One aspect of the present invention provides a method for cascade extraction of associated resources in produced water, comprising the following steps:

[0006] S1. Through pre-separation treatment, the target divalent ions and target monovalent ions in the extracted water are separated to obtain concentrated water containing the target divalent ions, and tailings containing at least impurity divalent ions, bromide ions and target monovalent ions.

[0007] S2. Remove the divalent ions of impurities from the concentrated tailings water to obtain the target monovalent ion solution;

[0008] S3. Electrolyze the target monovalent ion solution to extract bromine, obtaining liquid bromine and bromine extraction tail water;

[0009] S4. Extract the target monovalent ion from the bromine extraction tailwater by adsorption / desorption to obtain a target monovalent ion-rich desorption solution, wherein the concentration of the target monovalent ion is not less than 0.2 g / L and the concentration of the impurity divalent ion is not higher than 3% of the initial concentration of impurity divalent ions in the extracted water;

[0010] S5. The target monovalent ion and the target divalent ion are recovered from the target monovalent ion-rich desorption solution and the target divalent ion-rich concentrate, respectively.

[0011] According to the present invention, in the target monovalent ion-rich desorption solution, the concentration of the target monovalent ion is not less than 1 g / L.

[0012] According to the present invention, the target divalent ion includes strontium ions; and / or the target monovalent ion includes lithium ions; and / or the impurity divalent ion includes at least calcium ions and / or magnesium ions.

[0013] According to the present invention, in the target monovalent ion solution, the concentration of the target monovalent ion is not less than 90% of the initial concentration of the target monovalent ion in the produced water, the concentration of the target divalent ion is not more than 15% of the initial concentration of the target divalent ion in the produced water, and the concentration of the impurity divalent ion is not more than 10% of the initial concentration of the impurity divalent ion in the produced water; and / or

[0014] In the target divalent ion concentrate, the concentration of the target divalent ion is not less than 800 mg / L, and the concentration of the impurity divalent ion is not more than 60 mg / L.

[0015] According to the present invention, in step S1,

[0016] Using a first ion exchange resin, the target divalent ions are retained from the extracted water to obtain a diluted tailings water; the target divalent ions retained by the first ion exchange resin are eluted to obtain a concentrated water containing the target divalent ions.

[0017] and / or

[0018] In step S2, the second ion exchange resin is used to intercept the divalent impurity ions from the concentrated tailings water to obtain the target monovalent ion solution.

[0019] According to the present invention, the first ion exchange resin selectively adsorbs the target divalent ion; and / or

[0020] The second ion exchange resin selectively adsorbs the divalent impurity ions.

[0021] According to the present invention, the first ion exchange resin is ion exchange resin D001 or ion exchange resin DJH003; and / or

[0022] The second ion exchange resin is a calcium-magnesium chelating resin;

[0023] Preferably, the target divalent ions retained on the first ion exchange resin are eluted by sequentially performing water washing and first acid rinsing.

[0024] Preferably, the first acid solution is a 3-6 wt% aqueous solution of sulfuric acid.

[0025] According to the present invention, in step S4, the bromine extraction tail water is passed through an adsorption device to selectively adsorb the target monovalent ions; after the adsorption device reaches the adsorption endpoint, desorption is performed to obtain the target monovalent ion-rich desorbent solution.

[0026] According to the present invention, the number of adsorption devices is n, where n is an integer ≥ 1; and / or

[0027] The adsorption device is filled with a target monovalent ion selective adsorbent;

[0028] Preferably, the target monovalent ion selective adsorbent includes any one of titanium-based adsorbents, manganese-based adsorbents, and aluminum-based adsorbents.

[0029] According to the present invention, the desorption is performed on the adsorption device using a second acid solution or water;

[0030] Preferably, the second acid solution comprises dilute hydrochloric acid with a pH of 1.5-2.0.

[0031] According to the present invention, in step S5, the recovery of the target monovalent ion and the target divalent ion are carried out simultaneously.

[0032] According to the present invention, in step S5, the target monovalent ion is recovered in the following manner:

[0033] The desorption solution rich in target monovalent ions is concentrated using a reverse osmosis membrane to obtain a concentrate, which is then evaporated to obtain a target monovalent ion mother liquor. A target monovalent ion precipitant is added to the target monovalent ion mother liquor to precipitate the target monovalent ions, thus completing the recovery of the target monovalent ions.

[0034] Preferably, the concentration of the target monovalent ion in the concentrate is 2-5 g / L; and / or

[0035] In the target monovalent ion mother liquor, the concentration of the target monovalent ion is 15-20 g / L.

[0036] According to the present invention, in step S5, the target divalent ion is recovered in the following manner:

[0037] The target divalent ion concentrate is obtained by concentrating the water using a reverse osmosis membrane to obtain the target divalent ion mother liquor; the target divalent ion precipitant is added to the target divalent ion mother liquor to precipitate the target divalent ion, thereby completing the recovery of the target divalent ion;

[0038] Preferably, the concentration of the target divalent ion in the target divalent ion mother liquor is 1-5 g / L.

[0039] According to the present invention, the target monovalent ion precipitant comprises sodium carbonate; and / or

[0040] The target divalent ion precipitant includes ammonium carbonate and / or ammonium bicarbonate.

[0041] The beneficial effects of this invention are:

[0042] To address the problems of existing technologies for the comprehensive utilization of associated resources in produced water, such as long process flows, cumbersome processes, and high energy consumption, which are unsuitable for the reinjection treatment requirements of produced water in oil and gas fields, this invention provides a tiered extraction method for associated resources in produced water. Compared with existing technologies, the tiered extraction method for associated resources in produced water has at least the following advantages:

[0043] 1. A pre-separation step was designed to initially separate divalent strontium ions in the extracted water from divalent impurities including lithium ions, other monovalent ions, calcium ions, and magnesium ions. These impurities are removed before electrolytic bromine extraction and lithium ion adsorption / desorption. This avoids scale formation on the electrodes by calcium and magnesium ions during electrolytic bromine extraction, which would affect bromine extraction efficiency and reduce electrode lifespan. It also avoids interference from divalent ions such as strontium, calcium, and magnesium ions during lithium ion adsorption, preventing the introduction of impurities like calcium and magnesium ions into the lithium-rich desorption solution. Furthermore, [further details are needed]. The extraction of strontium avoids interference from monovalent ions such as lithium and sodium ions during the extraction process, reducing the operating pressure of subsequent lithium and strontium separation and purification stages, and further contributing to the efficient extraction of lithium and strontium. Specifically, after 30 days of stable operation in the heat exchange electrolytic cell, the voltage between the anode and cathode hardly increases compared to before electrolysis, and there is no obvious scaling on the electrode surface. In the obtained lithium-rich desorption solution, the concentration of lithium ions is not less than 0.2 g / L, preferably not less than 1 g / L, and the concentration of divalent impurity ions is not higher than 3% of the initial concentration of divalent impurity ions in the extracted water.

[0044] 2. The process of extracting strontium, bromine, and lithium is organically connected in series or in parallel. The recovery steps of strontium and lithium can also be carried out simultaneously. With a simpler process flow and lower energy consumption, it can achieve efficient cascade extraction of elements such as bromine, lithium, and strontium in produced water that have reached a certain abundance and exceed the grade of comprehensive industrial mining. This helps to reduce the waste of associated resources in produced water. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the steps in the stepwise extraction method of associated resources in produced water provided by the present invention;

[0046] Figure 2 This is a schematic diagram of the main process of the stepwise extraction method for associated resources in produced water provided by the present invention. Detailed Implementation

[0047] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0048] The produced water from oilfields contains multiple elements, including lithium, strontium, and bromine, exceeding the industrial grade for comprehensive utilization. The complete extraction of associated resources from produced water can bring significant economic benefits. However, existing technologies for extracting associated resources from produced water lack a complete and comprehensive extraction process for various associated resources, and suffer from problems such as long processes, cumbersome extraction procedures, high energy consumption, and incompatibility with the reinjection treatment requirements of produced water from oil and gas fields. This invention, through process design, integrates the extraction of associated resources from produced water, including bromine and other monovalent and divalent ions, forming a complete and comprehensive extraction process for associated resources. This fills a gap in existing technologies, enhances the utilization of associated resources in produced water, and can bring immeasurable economic benefits.

[0049] The first aspect of this invention provides a method for cascade extraction of associated resources from produced water, comprising the following steps: S1. Separating target divalent ions and target monovalent ions from the produced water through pre-separation treatment to obtain a target divalent ion concentrate and a reduced-concentration tailwater containing at least impurity divalent ions, bromide ions, and target monovalent ions; S2. Removing the impurity divalent ions from the reduced-concentration tailwater to obtain a target monovalent ion solution; S3. Electrolyzing the target monovalent ion solution to extract bromine, obtaining liquid bromine and bromine extraction tailwater; S4. Extracting the target monovalent ions from the bromine extraction tailwater by adsorption / desorption to obtain a target monovalent ion-rich desorption solution, wherein the concentration of the target monovalent ions is not less than 0.2 g / L, and the concentration of the impurity divalent ions is not higher than 3% of the initial concentration of impurity divalent ions in the produced water; S5. Recovering the target monovalent ions and target divalent ions from the target monovalent ion-rich desorption solution and the target divalent ion concentrate, respectively. The method for cascade extraction of associated resources in produced water provided by this invention creatively designs a specific extraction sequence. First, through pre-separation treatment, the target divalent ions are initially separated. Then, impurity divalent ions are removed, followed by electrolytic bromine extraction. Next, the target monovalent ions are separated and extracted. The concentration of target monovalent ions in the target monovalent ion-rich desorption solution obtained during the adsorption / desorption stage is strictly limited to achieve better extraction results. Finally, the target monovalent and divalent ions are recovered from the target monovalent ion-rich desorption solution and the target divalent ion concentrate. This method not only recovers the target divalent and monovalent ions but also essentially removes impurity divalent ions before electrolytic bromine extraction, preventing scale formation on the inner wall of the electrolysis equipment during the electrolytic bromine extraction process, which would affect the efficiency of the electrolytic bromine extraction and reduce the service life of the electrolysis equipment. This invention also limits the concentrations of the target monovalent ion, target divalent ion, and impurity divalent ion in the target monovalent ion solution and the target divalent ion concentrate. For example, in the target monovalent ion solution, the concentration of the target monovalent ion is not less than 90% of the initial concentration of the target monovalent ion in the extracted water, the concentration of the target divalent ion is not more than 15% of the initial concentration of the target divalent ion in the extracted water, and the concentration of the impurity divalent ion is not more than 10% of the initial concentration of the impurity divalent ion in the extracted water; and / or the concentration of the target divalent ion is not less than 800 mg / L, and the concentration of the impurity divalent ion is not more than 60 mg / L. Combined with the above-mentioned extraction sequence design and the limitations on the concentrations of the target monovalent ion and impurity divalent ion in the target monovalent ion-rich desorption solution, this further facilitates achieving better extraction effects of the target divalent ion, target monovalent ion, and bromide ion.

[0050] Besides the associated resources available for extraction, produced water generally contains a large amount of oil and some suspended solids. If these oil and suspended solids are not removed beforehand, they will affect the extraction efficiency of subsequent associated resources. Therefore, in the tiered extraction method for associated resources in produced water provided by this invention, preferably, the produced water is first subjected to oil and suspension removal treatment, and then the above steps S1 to S5 are performed sequentially. The apparatus or equipment required for oil and suspension removal treatment of produced water and the specific operating steps are prior art and will not be described here.

[0051] For typical produced water, the target monovalent ion includes lithium ions, and the target divalent ion includes strontium ions.

[0052] In addition to the target monovalent and divalent ions, produced water typically contains impurity divalent ions, such as calcium and / or magnesium ions, which cannot be removed by oil and suspension removal treatments. Practice has shown that these impurity divalent ions significantly interfere with subsequent electrolytic bromine extraction and the adsorption of the target monovalent ions. Therefore, it is necessary to remove these impurity divalent ions before the electrolytic bromine extraction step and the target monovalent ion adsorption / desorption step. In step S1, the produced water undergoes the pre-separation treatment to initially separate the target divalent ions. In step S2, the impurity divalent ions are removed from the concentrated tailings water containing at least impurity divalent ions, bromide ions, and target monovalent ions. This avoids scaling of impurity divalent ions during the electrolytic bromine extraction process in step S3 and reduces interference from impurity divalent ions on the target monovalent ion extraction process during the adsorption / desorption process in step S4, laying the foundation for the subsequent electrolytic bromine extraction in step S3 and the adsorption / desorption steps in step S4. In the prior art, there are many types of separation media capable of separating monovalent and divalent ions. Considering the chemical composition of the produced water itself, the specific types of the target monovalent and divalent ions, and the separation effect to be achieved in the pre-separation treatment, the present invention preferably uses ion exchange resin to separate the target divalent and monovalent ions in the produced water.

[0053] In a preferred embodiment of the present invention, in step S1, the pre-separation treatment of the produced water is performed using a first ion exchange resin: the first ion exchange resin is used to retain the target divalent ion (e.g., strontium ion) from the produced water to obtain a reduced concentration tailings water; the reduced concentration tailings water contains at least impurity divalent ions (e.g., calcium ion, magnesium ion), bromide ions and the target monovalent ion (e.g., lithium ion); the target divalent ions retained by the first ion exchange resin are eluted to obtain the target divalent ion concentrate.

[0054] In a preferred embodiment of the present invention, in step S2, the second ion exchange resin is used to retain the impurity divalent ions from the concentrated tailings water to obtain the target monovalent ion solution.

[0055] Through the above two preferred embodiments, not only are impurity divalent ions removed before electrolytic bromine extraction and adsorption / desorption of target monovalent ions, thus avoiding scaling of impurity divalent ions during electrolytic bromine extraction and interference with the adsorption / desorption process of target monovalent ions, but also useful target divalent ions are extracted.

[0056] In one specific embodiment of the present invention, the first ion exchange resin selectively adsorbs the target divalent ion; the second ion exchange resin selectively adsorbs the impurity divalent ion.

[0057] The specific types of the first ion exchange resin and the second ion exchange resin are determined based on the target divalent ion, the target monovalent ion, and the impurity divalent ion in the extracted water.

[0058] In a specific embodiment of the present invention, in order to achieve a better pre-separation effect, the first ion exchange resin is ion exchange resin D001 or ion exchange resin DJH003; wherein, the first ion exchange resin has a target divalent ion affinity functional group; further, the target divalent ion affinity functional group includes a sulfonic acid group.

[0059] In one specific embodiment of the present invention, the second ion exchange resin is a calcium-magnesium chelate resin.

[0060] In a preferred embodiment of the present invention, in step S1, the extracted water is first passed into an ion exchange column filled with the first ion exchange resin. The first ion exchange resin is used to selectively adsorb the target divalent ion, thereby retaining the target divalent ion from the extracted water. Meanwhile, monovalent ions, including the target monovalent ion, and the impurity divalent ion are hardly selectively adsorbed by the first ion exchange resin and flow out of the ion exchange column, resulting in a reduced-concentration tailwater containing at least the impurity divalent ion, bromide ion, and the target monovalent ion.

[0061] Next, the ion exchange column filled with the first ion exchange resin is sequentially washed with water and rinsed with the first acid solution to elute the target divalent ions trapped on the first ion exchange resin. The effluent is collected from the outlet of the ion exchange column filled with the first ion exchange resin, which is the target divalent ion concentrate.

[0062] In a preferred embodiment of the present invention, in step S2, the diluted tailwater is passed into an ion exchange column filled with the second ion exchange resin. The second ion exchange resin selectively adsorbs the divalent impurity ions, thereby retaining the divalent impurity ions in the diluted tailwater. Meanwhile, monovalent ions (e.g., bromide ions) containing the target monovalent ion are hardly selectively adsorbed by the second ion exchange resin and flow out from the ion exchange column filled with the second ion exchange resin to obtain the target monovalent ion solution.

[0063] Furthermore, to achieve continuous cascade extraction of associated resources from the produced water, on the one hand, after collecting the concentrated water containing the target divalent ions, the ion exchange column filled with the first ion exchange resin is washed with water to remove the residual first acid solution on the first ion exchange resin, and then the first ion exchange resin is transformed by rinsing with an alkaline solution. Finally, the residual alkaline solution on the first ion exchange resin is washed with water to regenerate the first ion exchange resin, enabling it to continue selectively adsorbing the target divalent ions; wherein, the first acid solution and the alkaline solution are determined according to the specific type of the first ion exchange resin. On the other hand, after the target monovalent ion solution is collected, the selective adsorption of the impurity divalent ions by the second ion exchange resin reaches the adsorption endpoint. The ion exchange column filled with the second ion exchange resin is washed with water and then rinsed with a third acid solution to wash off the impurity divalent ions trapped on the second ion exchange resin. Then, the residual third acid solution on the second ion exchange resin is removed by water washing, and then the second ion exchange resin is transformed by alkali rinsing. Finally, the residual alkali solution on the second ion exchange resin is removed by water washing, so that the second ion exchange resin is regenerated and can continue to selectively adsorb the impurity divalent ions.

[0064] In one embodiment of the present invention, the first acid solution is an aqueous solution of sulfuric acid, wherein the mass fraction of sulfuric acid is 3-6 wt%.

[0065] In one embodiment of the present invention, the third acid solution is an aqueous solution of hydrochloric acid, wherein the mass fraction of hydrochloric acid is 5-10 wt%.

[0066] In one embodiment of the present invention, the alkaline solution is an aqueous solution of sodium hydroxide, wherein the mass fraction of sodium hydroxide is 5 wt%.

[0067] In this invention, since the target monovalent ion solution obtained in step S2 contains almost no impurity divalent ions such as calcium and magnesium ions, bromine can be directly extracted from the target monovalent ion solution by electrolysis in step S3. That is, electrolysis is used to remove the trace amounts of residual organic matter or oil in the target monovalent ion solution through oxidative degradation; simultaneously, chloride ions are oxidized to chlorine gas; the generated chlorine gas further reacts with bromide ions in the target monovalent ion solution to obtain elemental bromine, thus achieving the extraction of bromine from the extracted water.

[0068] In a specific embodiment of the present invention, in step S3, the target monovalent ion solution is subjected to electrolytic bromine extraction according to the following steps:

[0069] S3-1. Electrolyze the target monovalent ion solution to obtain an electrolyzed target monovalent ion solution containing bromine, chlorine and hydrogen.

[0070] S3-2. Heating the electrolyzed target monovalent ion solution causes the elemental bromine in it to be converted into bromine gas, which escapes along with chlorine and hydrogen gas, yielding a mixed gas and the bromine extraction tail water;

[0071] S3-3 obtains bromine gas from the mixed gas by reduction with a reducing liquid and oxidative distillation;

[0072] S3-4 involves heat exchange between the bromine gas and the electrolyzed target monovalent ion solution, heating the electrolyzed target monovalent ion solution, while the bromine gas cools down to obtain the liquid bromine.

[0073] In a specific embodiment of the present invention, in step S3-1, during the electrolysis process, in the target monovalent ion solution, chloride ions are converted into chlorine gas by anodic oxidation, bromide ions are converted into elemental bromine by anodic oxidation and / or chlorine gas oxidation, and hydrogen ions are converted into hydrogen gas by cathode reduction; elemental bromine, chlorine gas and hydrogen gas are dissolved or dispersed in the target monovalent ion solution after electrolysis.

[0074] In one specific embodiment of the present invention, in step S3-2, the mixed gas includes bromine, chlorine and hydrogen.

[0075] In a specific embodiment of the present invention, in step S3-3, the mixed gas is injected into the reducing liquid, and the chlorine and bromine are reduced to hydrogen chloride and hydrogen bromide by the reducing substances in the reducing liquid, thereby obtaining a gas-liquid mixture containing hydrogen chloride, hydrogen bromide and hydrogen.

[0076] The gas-liquid mixture is subjected to gas-liquid separation to obtain a hydrogen chloride-hydrogen bromide mixed solution and tail gas; the hydrogen chloride-hydrogen bromide mixed solution is subjected to oxidative distillation, and the bromide is oxidized to elemental bromine by oxidizing gas; the elemental bromine is then distilled to obtain bromine gas.

[0077] In a specific embodiment of the present invention, in steps S3-4, the bromine gas and the electrolyzed target monovalent ion solution are heat-exchanged, and the heat from the distilled bromine gas is used to heat the electrolyzed target monovalent ion solution. During this process, the bromine gas is converted into liquid bromine due to the decrease in temperature.

[0078] In one specific embodiment of the present invention, the reducing liquid is an aqueous solution of sulfur dioxide; the aqueous solution of sulfur dioxide is prepared by simultaneously introducing sulfur dioxide gas and water.

[0079] Based on the above method for preparing sulfur dioxide aqueous solution, excess sulfur dioxide gas exists in the gas-liquid mixture. After gas-liquid separation, the sulfur dioxide gas is transferred to the tail gas. The amount of carbon dioxide gas introduced is controlled by monitoring the sulfur dioxide content in the tail gas, thereby controlling the concentration of sulfur dioxide in the sulfur dioxide aqueous solution.

[0080] In one specific embodiment of the present invention, the sulfur dioxide content in the exhaust gas is 20-30 mg / kg.

[0081] In one specific embodiment of the present invention, the oxidizing gas is chlorine.

[0082] In this invention, since the pre-separation treatment of the produced water has already been performed in step S1, the separation of the target divalent ions and target monovalent ions in the produced water has been achieved in advance. Furthermore, the impurity divalent ions have been largely removed in step S2, eliminating the interference of the impurity divalent ions during the adsorption and desorption process of the target monovalent ions in step S4. Therefore, in the adsorption / desorption step of step S4, it is not necessary to extract various associated resources in the produced water sequentially as in the general process of existing technologies. Instead, the target monovalent ions are directly adsorbed / desorbed to obtain the target monovalent ion-rich desorbent. This simplifies the process operation, reduces the extraction time, and improves the extraction efficiency.

[0083] In a specific embodiment of the present invention, in step S4, the bromine extraction tail water is passed through an adsorption device for selective adsorption of the target monovalent ion; after the adsorption device reaches the adsorption endpoint, desorption is performed to obtain the desorbed liquid rich in the target monovalent ion. During the selective adsorption of the target monovalent ion, the liquid flowing out of the outlet of the adsorption device is called the adsorption tail liquid; when the pH of the adsorption tail liquid is <4, the adsorption device is considered to have reached the adsorption endpoint; the concentration of the target monovalent ion in the adsorption tail liquid is not higher than 30 mg / L.

[0084] In one specific embodiment of the present invention, the adsorption device is filled with a target monovalent ion selective adsorbent.

[0085] In a preferred embodiment of the present invention, the target monovalent ion selective adsorbent is any one of titanium-based adsorbents, manganese-based adsorbents, and aluminum-based adsorbents.

[0086] In one specific embodiment of the present invention, the number of adsorption devices is n, where n is an integer ≥ 1. The adsorption device can be referred to as n groups of adsorption devices; each group of adsorption devices includes at least one adsorption column.

[0087] In one specific embodiment of the present invention, the n groups of adsorption devices are connected in series or in parallel.

[0088] In one specific embodiment of the present invention, in the n groups of adsorption devices, the adsorption columns in each group of adsorption devices are connected in series or in parallel.

[0089] In one specific embodiment of the present invention, the desorption of the adsorption device is performed using a second acid solution or water. Specifically, when the adsorption device is filled with the titanium-based adsorbent or the manganese-based adsorbent, the adsorption device is desorbed using the second acid solution; the desorption can be conventional acid circulation desorption, which is prior art and will not be described in detail here; when the adsorption device is filled with the aluminum-based adsorbent, the adsorption device is desorbed using water.

[0090] In a specific embodiment of the present invention, when the desorption is acidic cyclic desorption, the concentration of the target monovalent ion in the target monovalent ion-rich desorption solution is not less than 0.2 g / L.

[0091] In one specific embodiment of the present invention, the second acid solution comprises dilute hydrochloric acid with a pH of 1.5-2.0.

[0092] In a preferred embodiment of the present invention, the adsorption device is filled with the titanium-based adsorbent, and the adsorption device is desorbed using the second acid solution.

[0093] In a preferred embodiment of the present invention, when n is an integer ≥2, the desorption process of the adsorption device adopts a segmented cyclic concentration desorption method. The segmented cyclic concentration desorption includes surface desorption and internal pore rinsing performed in stages sequentially; firstly, the adsorption device, having reached the adsorption endpoint, undergoes one instance of surface desorption to desorb the target monovalent ions adsorbed on the surface of the target monovalent ion selective adsorbent; then, the adsorption device undergoes at least one instance of internal pore rinsing to allow the residual target monovalent ions in the internal pores of the target monovalent ion selective adsorbent to migrate down, resulting in the target monovalent ion-rich desorption solution.

[0094] In a preferred embodiment of the present invention, when the desorption is a segmented cyclic concentration desorption, the concentration of the target monovalent ion in the target monovalent ion-rich desorption solution is not less than 1 g / L.

[0095] In a more preferred embodiment of the present invention, the segmented cyclic concentration desorption is performed according to the following steps:

[0096] When n = 2 or n is an integer ≥ 3, the first adsorption device is subjected to surface desorption once with the second acid solution to generate the first-stage desorption solution; the first adsorption device is subjected to internal pore rinsing n-1 times with the washing solution, and the rinsing solution generated each time is collected separately.

[0097] When n is an integer ≥ 3, the eluent generated from the first internal pore rinsing of the (m-1)th adsorption device and the second acid solution are combined to perform the surface desorption of the m-th adsorption device once, generating the m-th stage desorption solution; the eluent generated from the second to n-(m-1)th internal pore rinsing of the (m-1)th adsorption device is used to perform nm rinsing of the internal pores of the m-th adsorption device, and the eluent generated from each rinsing is collected separately; m is an integer from 2 to (n-1);

[0098] When n = 2 or n is an integer ≥ 3, the rinsing liquid generated from the first internal pore rinsing of the (n-1)th adsorption device and the second acid solution are combined, and the surface desorption of the nth adsorption device is performed once to generate the nth stage desorption liquid; the internal pore rinsing of the nth adsorption device is performed at least once with the rinsing liquid, and the resulting rinsing liquid is combined into the adsorption tail liquid.

[0099] Collect the desorption solutions from the first to the nth stage to obtain the target-rich monovalent ion-rich desorption solution;

[0100] After the internal pores have been rinsed, the adsorption device continues to selectively adsorb the target monovalent ions.

[0101] In one specific embodiment of the present invention, the adsorption device is assembled in the form of a fixed bed or a continuous ion exchange.

[0102] In a specific embodiment of the present invention, when the adsorption device is assembled in a fixed-bed manner, the segmented cyclic concentration and desorption are performed according to the following steps:

[0103] When n = 2 or n is an integer ≥ 3, the second acid solution is passed into the first adsorption device to perform the surface desorption once, generating the first-stage desorption solution; the washing solution is passed into the first adsorption device to perform the internal pore rinsing n-1 times, and the rinsing solution generated each time is collected separately.

[0104] When n is an integer ≥ 3, the eluent generated from the first internal pore rinsing of the (m-1)th adsorption device and the second acid solution are combined and passed into the m-th adsorption device for the first surface desorption to generate the m-th desorption solution; the eluent generated from the second to n-(m-1) internal pore rinsing of the (m-1)th adsorption device is passed into the m-th adsorption device to perform nm internal pore rinsing on the m-th adsorption device, and the eluent generated from each rinsing is collected, where m is an integer from 2 to (n-1);

[0105] When n = 2 or n is an integer ≥ 3, the rinsing solution generated from the first internal pore rinsing of the (n-1)th adsorption device is combined with the second acid solution and passed into the nth adsorption device for one surface desorption to generate the nth stage desorption solution; the rinsing solution is passed into the nth adsorption device for at least one internal pore rinsing, and the resulting rinsing solution is combined with the adsorption tail liquid.

[0106] Collect the desorption solutions from the first to the nth stage to obtain the target ion-rich desorption solution;

[0107] After the internal pores have been rinsed, the adsorption device continues to selectively adsorb the target monovalent ions.

[0108] In a specific embodiment of the present invention, when the adsorption device is assembled in a continuous ion exchange manner, an adsorption zone, a surface desorption zone, and an internal pore rinsing zone are provided; wherein, the number of adsorption sites in the adsorption zone is at least the number of adsorption columns in each adsorption device group; the number of desorption sites in the surface desorption zone is at least the number of adsorption columns in each adsorption device group / (the ratio of surface desorption rate to adsorption rate); the number of rinsing sites in the internal pore rinsing zone is at least the number of adsorption columns in each adsorption device group / (the ratio of internal rinsing rate to adsorption rate); the n adsorption devices cyclically move along the route of adsorption sites, desorption sites, rinsing sites, and adsorption sites, sequentially performing selective adsorption of target monovalent ions, surface desorption, and internal pore rinsing, followed by selective adsorption of the target monovalent ions, continuously and cyclically performing selective adsorption of target monovalent ions and segmented cyclic concentration desorption; n is an integer ≥2. Based on the above settings, the segmented cyclic concentration desorption is performed according to the following steps:

[0109] When n = 2 or n is an integer ≥ 3, the first adsorption device is moved to the desorption position, and the second acid solution is introduced to perform the surface desorption once to generate the first-stage desorption solution; then the first adsorption device is moved to the rinsing position, and the rinsing solution is introduced to perform the internal pore rinsing n-1 times, and the rinsing solution generated each time is collected separately.

[0110] When n is an integer ≥ 3, the m-th adsorption device is moved to the desorption position, and the eluent generated by the first internal pore rinsing of the (m-1)-th adsorption device and the second acid solution are combined and introduced to perform the first surface desorption, generating the m-th stage desorption solution; then the m-th adsorption device is moved to the rinsing position, and the eluent generated by the second to n-(m-1) internal pore rinsing of the (m-1)-th adsorption device is introduced to perform nm internal pore rinsing, and the eluent generated by each rinsing is collected; where m is an integer from 2 to (n-1);

[0111] When n = 2 or n is an integer ≥ 3, the nth adsorption device is moved to the desorption position, and the rinsing liquid generated from the first internal pore rinsing of the (n-1)th adsorption device and the second acid solution are combined and introduced to perform the surface desorption once, generating the nth stage desorption liquid; then the nth adsorption device is moved to the rinsing position, and the rinsing liquid is introduced to perform at least one internal pore rinsing, and the resulting rinsing liquid is combined with the adsorption tail liquid;

[0112] Collect the desorption solutions from the first to the nth stage to obtain the target-rich monovalent ion-rich desorption solution;

[0113] After completing the internal pore rinsing, the adsorption device moves to the adsorption site to continue the selective adsorption of the target monovalent ion.

[0114] In one specific embodiment of the present invention, the washing solution is water.

[0115] In one specific embodiment of the present invention, the rinsing rate of the internal pores is 1 to 5 times the desorption rate of the surface layer.

[0116] In a specific embodiment of the present invention, when the n sets of adsorption devices are assembled in a continuous ion exchange manner, the surface desorption rate is 2 to 4 times the adsorption rate; n is an integer ≥ 2.

[0117] In a specific embodiment of the present invention, when any one of the adsorption devices in the second to nth groups performs the surface desorption, the pH of the combined solution of the second acid and the rinsing solution generated by the first internal pore rinsing of the previous adsorption device is 1.5-2.0; n is an integer ≥2.

[0118] For the adsorption device, whether a fixed-bed assembly or a continuous ion exchange assembly is used for the segmented cyclic concentration and desorption, the target monovalent ions adsorbed on the surface of the target monovalent ion selective adsorbent are first desorbed using a second acid solution (or a combination of the second acid solution and the eluent generated from the first internal pore rinsing of the previous adsorption device), i.e., surface desorption; then, the residual target monovalent ions in the internal pores of the target monovalent ion selective adsorbent are migrated out by the concentration gradient using the washing solution (or the eluent generated from the second to the last internal pore rinsing of the previous adsorption device), i.e., internal pore rinsing; in this way, the target monovalent ions adsorbed by the target monovalent ion selective adsorbent can be completely desorbed. Furthermore, since the surface desorption is performed only once during the segmented cyclic concentration desorption process, meaning that the second acid solution is used only once during the segmented cyclic concentration desorption process of a set of adsorption devices, unlike traditional acid solution cyclic desorption, this significantly reduces the concentration inhibition effect caused by the presence of a certain concentration of already desorbed target monovalent ions in the second acid solution on the subsequent target monovalent ion desorption process. After the surface desorption is performed once, the internal pores are rinsed. With the help of the concentration gradient, the release of residual target monovalent ions in the internal pores of the target monovalent ion selective adsorbent is promoted, and the residual target monovalent ions migrate down, achieving complete desorption of the target monovalent ions.

[0119] In one specific embodiment of the present invention, before the desorption or the segmented cyclic concentration desorption, the adsorption device is rinsed with water to remove impurities after reaching the adsorption endpoint.

[0120] In a preferred embodiment of the present invention, in step S5, the recovery of the target monovalent ion and the target divalent ion is carried out simultaneously.

[0121] In one specific embodiment of the present invention, in step S5, the target monovalent ion is recovered in the following manner:

[0122] The desorption solution rich in target monovalent ions is concentrated using a reverse osmosis membrane to obtain a concentrate, which is then evaporated to obtain a target monovalent ion mother liquor. A target monovalent ion precipitant is added to the target monovalent ion mother liquor to precipitate the target monovalent ions, thus completing the recovery of the target monovalent ions.

[0123] In a preferred embodiment of the present invention, the concentration of the target monovalent ion in the concentrate is 2-5 g / L; and / or

[0124] In the target monovalent ion mother liquor, the concentration of the target monovalent ion is 15-20 g / L.

[0125] In one specific embodiment of the present invention, in step S5, the target divalent ion is recovered in the following manner:

[0126] The target divalent ion concentrate is obtained by concentrating the water using a reverse osmosis membrane to obtain the target divalent ion mother liquor; the target divalent ion precipitant is added to the target divalent ion mother liquor to precipitate the target divalent ion, thereby completing the recovery of the target divalent ion.

[0127] In a preferred embodiment of the present invention, the concentration of the target divalent ion in the target divalent ion mother liquor is 1-5 g / L.

[0128] In a preferred embodiment of the present invention, in step S5, when the target divalent ion mother liquor contains the impurity divalent ions, before adding the target divalent ion precipitant, an impurity precipitant is added to precipitate the impurity divalent ions.

[0129] In one specific embodiment of the present invention, the target monovalent ion precipitant includes sodium carbonate; and / or

[0130] The target divalent ion precipitant includes ammonium carbonate and / or ammonium bicarbonate; and / or

[0131] The impurity precipitant includes strontium hydroxide.

[0132] It should be noted that after steps S1 to S5, the target monovalent ion precipitate obtained by precipitating the target monovalent ion inevitably contains a very small amount of impurity monovalent ions (e.g., sodium ions and / or potassium ions) and / or the impurity divalent ions; the target divalent ion precipitate obtained by precipitating the target divalent ion inevitably contains a very small amount of the impurity monovalent ions and / or the impurity divalent ions.

[0133] In one specific embodiment of the present invention, when the content of impurity monovalent ions (e.g., sodium ions and / or potassium ions) in the target monovalent ion precipitate obtained by precipitating the target monovalent ion exceeds the standard, the target monovalent ion precipitate is washed with hot water at a temperature not lower than 90°C, and then centrifuged and dried to obtain the purified target monovalent ion precipitate; or when the content of impurity divalent ions in the target monovalent ion precipitate exceeds the standard, the impurity precipitant is first added to the target monovalent ion mother liquor to precipitate the impurity divalent ions, the filtrate is collected by filtration, and then the target monovalent ion precipitant is added to it to precipitate the target monovalent ions and complete the recovery of the target monovalent ions.

[0134] In one specific embodiment of the present invention, when the content of impurity monovalent ions (e.g., sodium ions and / or potassium ions) in the target divalent ion precipitate obtained by precipitating the target divalent ions exceeds the standard, the target divalent ion precipitate is washed with hot water at a temperature not lower than 90°C, and then centrifuged and dried to obtain the purified target divalent ion precipitate; or when the impurity divalent ions in the target divalent ion precipitate exceed the standard, the impurity precipitant is first added to the target divalent ion mother liquor to precipitate the impurity divalent ions, the filtrate is collected by filtration, and then the target divalent ion precipitant is added to it to precipitate the target divalent ions and complete the recovery of the target divalent ions.

[0135] In one specific embodiment of the present invention, the process of precipitating the impurity divalent ions and the target divalent ions is carried out at room temperature; the process of precipitating the target monovalent ions is carried out at a temperature not lower than 90°C.

[0136] It should be noted that the "excessive use of monovalent ions" or "excessive use of divalent ions" mentioned in this invention refers to the maximum concentration requirements for monovalent and / or divalent ions in industrial or battery applications.

[0137] It should also be noted that, based on the above-mentioned method for cascade extraction of associated resources in produced water provided by the present invention, according to the endowment conditions of associated resources in produced water, an extraction step for cesium and rubidium is added. For example, after regenerating the second ion exchange resin, the resulting regenerated liquid is used to perform adsorption and desorption of cesium or rubidium using an adsorption device filled with an adsorbent capable of selectively adsorbing cesium or rubidium, thereby completing the extraction of cesium and rubidium from the produced water.

[0138] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0139] The ion exchange resin D001 used in the following examples and comparative examples was purchased from Xi'an Lanxiao Technology Co., Ltd.

[0140] Example 1

[0141] This embodiment employs the cascade extraction method for associated resources in produced water provided by the present invention to perform cascade extraction of associated resources from produced water with a chloride ion concentration of not less than 2 g / L from an oilfield. The produced water was found to contain: lithium ions 65 mg / L, bromide ions 230 mg / L, bicarbonate ions 150 mg / L, strontium ions 40 mg / L, oil 2500 mg / L, suspended solids 110 mg / L, calcium ions 730 mg / L, and magnesium ions 55 mg / L.

[0142] (1) The equipment and raw material information involved in steps S1 to S5 are as follows:

[0143] Heat exchange electrolytic cell: a ruthenium-iridium coated titanium-based electrode is used as the anode and an iron electrode is used as the cathode; the anode and cathode dimensions are 1m*1m, a total of 10 pairs of anode-cathode are set, and the current is set to 2000A;

[0144] An ion exchange column filled with a first ion exchange resin: wherein the first ion exchange resin is ion exchange resin D001;

[0145] An ion exchange column filled with a second ion exchange resin: wherein the second ion exchange resin is a calcium-magnesium chelating resin;

[0146] Four sets of adsorption devices in parallel: fixed bed type, each set of adsorption devices includes four adsorption columns connected in series, each adsorption column is filled with 1200g of titanium-based adsorbent; wherein, the titanium-based adsorbent is metatitanic acid type adsorbent.

[0147] A single adsorption column filled with titanium-based adsorbent, wherein the amount of titanium-based adsorbent is 1200g;

[0148] Titanium-based adsorbents are metatitanic acid type adsorbents;

[0149] Reducing liquid: an aqueous solution of sulfur dioxide prepared by simultaneously introducing sulfur dioxide and water;

[0150] First acid solution: 1.6 wt% sulfuric acid aqueous solution;

[0151] Second acid solution: dilute hydrochloric acid with a pH of 1.5-2.0;

[0152] Third acid solution: 10wt% dilute hydrochloric acid;

[0153] Alkaline solution: Sodium hydroxide aqueous solution, wherein the mass fraction of NaOH is 5 wt%.

[0154] (2) Figure 1 , Figure 2 As shown, using strontium ions as the target divalent ion and lithium ions as the target monovalent ion, the associated resources in the produced water are extracted in a cascade manner through the following steps:

[0155] First, the produced water is treated to remove oil and suspended solids, reducing the oil content to 45 mg / L and the suspended solids content to 31 mg / L. Then, the following steps S1 to S5 are performed.

[0156] S1. Through pre-separation treatment, the target divalent ions and target monovalent ions in the extracted water are separated to obtain concentrated water containing the target divalent ions, and tailings containing at least impurity divalent ions, bromide ions and target monovalent ions.

[0157] Specifically:

[0158] S1-1. Using the first ion exchange resin, target divalent ions are intercepted from the produced water to obtain concentrated tailings water;

[0159] The treated produced water, after being de-oiled and impurity removed, is passed into an ion exchange column filled with ion exchange resin D001. The ion exchange resin D001 selectively adsorbs strontium ions, thus retaining them in the produced water. Meanwhile, monovalent ions, including lithium ions such as bromide ions, as well as calcium and magnesium ions, are hardly selectively adsorbed by the ion exchange resin D001 and flow out of the ion exchange column, resulting in a reduced-concentration tailwater containing calcium, magnesium, bromide, and lithium ions.

[0160] S1-2. Elute the target divalent ions retained by the first ion exchange resin to obtain a concentrated solution of the target divalent ions;

[0161] Next, the ion exchange column filled with ion exchange resin D001 was sequentially washed with water and then rinsed with a 1.6 wt% sulfuric acid aqueous solution to elute the strontium ions retained on the ion exchange resin D001. The effluent was collected from the outlet of the ion exchange column, which is the strontium ion concentrate. The concentration of strontium ions in the strontium ion concentrate was measured to be 800 mg / L, calcium ions 55 mg / L, magnesium ions 6 mg / L, lithium ions 5 mg / L, and bicarbonate ions 150 mg / L.

[0162] S2. Remove divalent ions from the concentrated tailings water to obtain the target monovalent ion solution;

[0163] Specifically:

[0164] S2-1. Using a second ion exchange resin, divalent ions of impurities are intercepted from the concentrated tail water to obtain a solution of the target monovalent ion;

[0165] Specifically, the diluted tailwater obtained in step S1-1 is passed into an ion exchange column filled with calcium-magnesium chelating resin. Utilizing the selective adsorption of calcium and magnesium ions by the calcium-magnesium chelating resin, the calcium and magnesium ions in the diluted tailwater are retained, while monovalent ions such as lithium and bromide ions are hardly selectively adsorbed by the calcium-magnesium chelating resin. The tailwater flows out from the ion exchange column filled with calcium-magnesium chelating resin to obtain a lithium ion solution. The determination shows that the lithium ion solution obtained contains 52 mg / L of lithium ions, 5 mg / L of strontium ions, 70 mg / L of calcium ions, 5 mg / L of magnesium ions, and 150 mg / L of bicarbonate ions.

[0166] S2-2. To achieve continuous cascade extraction of associated resources from produced water, on the one hand, after collecting strontium ion concentrate, the ion exchange column filled with ion exchange resin D001 is first washed with water to remove residual sulfuric acid on the ion exchange resin D001, and then rinsed with 5wt% sodium hydroxide aqueous solution to achieve the transformation of ion exchange resin D001. Finally, it is washed with water to remove residual sodium hydroxide on the ion exchange resin D001, thereby regenerating the ion exchange resin D001 and enabling it to continue to selectively adsorb the strontium ions.

[0167] On the other hand, after the lithium ion solution is collected, when the selective adsorption of calcium and magnesium ions by the calcium-magnesium chelate resin in the ion exchange column filled with calcium-magnesium chelate resin reaches the adsorption endpoint, the adsorption column filled with calcium-magnesium chelate resin is washed with water and eluted with 10wt% dilute hydrochloric acid to elute the calcium and magnesium ions retained on the calcium-magnesium chelate resin. Then, water washing is performed to remove the residual dilute hydrochloric acid on the calcium-magnesium chelate resin, and then eluted with 5wt% sodium hydroxide aqueous solution to realize the transformation of the calcium-magnesium chelate resin. Finally, water washing is performed to remove the residual sodium hydroxide on the calcium-magnesium chelate resin, thereby regenerating the calcium-magnesium chelate resin so that it can continue to selectively adsorb calcium and magnesium ions.

[0168] S3. Electrolyze the target monovalent ion solution to extract bromine, obtaining liquid bromine and bromine extraction tail water;

[0169] Specifically:

[0170] S3-1. Electrolyze the lithium-ion solution obtained in step S2-1 to obtain an electrolyzed lithium-ion solution; the electrolyzed lithium-ion solution contains elemental bromine, chlorine gas and hydrogen gas.

[0171] A lithium-ion solution was passed through a heat exchange electrolytic cell for electrolysis to obtain an electrolyzed lithium-ion solution. During electrolysis, the residual free oil components in the lithium-ion solution were oxidized to 0.8 mg / L. Chloride ions were converted to chlorine gas by anodic oxidation, bromide ions were converted to elemental bromine by anodic oxidation and chlorine gas oxidation, and hydrogen ions were converted to hydrogen gas by cathode reduction. Elemental bromine, chlorine gas, and hydrogen gas dissolved or dispersed in the electrolyzed lithium-ion solution. The electrodes in the heat exchange electrolytic cell operated stably for more than 30 days. After electrolysis, the voltage between the anode and cathode was 5.05 V (the initial voltage before electrolysis was 5 V), and almost no scaling was observed on the surfaces of the anode and cathode.

[0172] S3-2. Heating and electrolyzing the lithium-ion solution causes the elemental bromine in it to be converted into bromine gas, which escapes along with chlorine and hydrogen gas, resulting in a mixed gas and bromine extraction tail water;

[0173] The temperature of the lithium-ion solution obtained after electrolysis in step S3-1 is heated to 20°C, where the elemental bromine is converted into bromine gas, which escapes along with chlorine and hydrogen gas, resulting in a mixed gas including bromine, chlorine and hydrogen, as well as bromine extraction tail water. The bromine extraction tail water was determined to contain: lithium ions 52 mg / L, strontium ions 5 mg / L, calcium ions 70 mg / L, magnesium ions 5 mg / L, and bicarbonate ions 140 mg / L.

[0174] S3-3. Bromine gas is obtained by separation and purification from the mixed gas through reduction with reducing liquid and oxidative distillation;

[0175] The sulfur dioxide aqueous solution is reacted with bromine and chlorine in the mixed gas obtained in step S3-2. The bromine and chlorine are reduced to hydrogen bromide and hydrogen chloride respectively by the bisulfite ions in the sulfur dioxide aqueous solution, resulting in a gas-liquid mixture containing hydrogen chloride, hydrogen bromide and hydrogen.

[0176] The obtained gas-liquid mixture was subjected to gas-liquid separation to obtain a mixed solution of hydrogen chloride and hydrogen bromide.

[0177] The obtained hydrogen chloride-hydrogen bromide mixed solution is subjected to oxidative distillation, specifically: the hydrogen chloride-hydrogen bromide mixed solution flows into the distillation column from the top, while chlorine gas and water vapor flow into the distillation column from the bottom. The chlorine gas oxidizes the bromide to elemental bromine on the packing material inside the distillation column; then, the generated elemental bromine is converted into bromine gas by steam distillation.

[0178] S3-4. Heat exchange is performed between bromine gas and the electrolyzed lithium-ion solution. Heating the electrolyzed lithium-ion solution causes the bromine gas to cool down, resulting in liquid bromine.

[0179] The bromine gas obtained from distillation in step S3-3 is exchanged with the lithium-ion solution after electrolysis for heat exchange. The heat carried by the bromine gas is used to heat the lithium-ion solution after electrolysis, raising its temperature to 20°C. During this process, the bromine gas is converted into liquid bromine due to the decrease in temperature. The purity of the liquid bromine is measured to be 91%.

[0180] S4. Extract the target monovalent ion from the target monovalent ion solution by adsorption / desorption to obtain a target monovalent ion-rich desorption solution, wherein the concentration of the target monovalent ion is not less than 0.2 g / L;

[0181] Specifically:

[0182] S4-1. The bromine extraction tailwater obtained in step S3-2 is passed into four sets of adsorption devices connected in parallel at a flow rate of 35 mL / min for lithium ion adsorption. After the adsorption devices have been running stably for 1 hour, the adsorption tail liquids flowing out of the four sets of adsorption devices are collected and combined. The lithium ion content in the adsorption tail liquid is measured to be reduced to 30 mg / L. Based on the fact that the average lithium ion content in the adsorption tail liquid after the adsorption devices have been running stably for 24 hours is 25 mg / L, the adsorption recovery rate of lithium ions by the adsorption devices can be calculated to be 52%.

[0183] S4-2. Water is passed through four sets of adsorption devices connected in parallel at a flow rate of 70 mL / min for one impurity removal rinse. Then, acid circulation desorption is performed sequentially on the four sets of adsorption devices: dilute hydrochloric acid is passed through the first set of adsorption devices at a flow rate of 70 mL / min for the first round of desorption, which lasts for 4 hours; the resulting desorption solution is then circulated through the first set of adsorption devices at a flow rate of 70 mL / min for four rounds of desorption, each round lasting for 4 hours, during which dilute hydrochloric acid is added to the desorption solution. Hydrochloric acid was used to maintain the pH of the desorption solution at 1.5-2.0. The second to fourth adsorption units were subjected to acid circulation desorption in the same manner. After the acid circulation desorption of lithium ions on the four adsorption units was completed, lithium-rich desorption solutions were collected from the outlets of the four adsorption units. The concentrations of lithium ions, calcium ions, magnesium ions, strontium ions, and bicarbonate ions in the lithium-rich desorption solutions were measured to be 0.2 g / L, 20 mg / L, 1 mg / L, 1 mg / L, and 1 mg / L, respectively.

[0184] S5. Recover the target monovalent ions and target divalent ions from the target monovalent ion-rich desorption solution and the target divalent ion-rich concentrate, respectively;

[0185] Specifically,

[0186] S5-1. Sodium hydroxide is added to the lithium-rich desorption solution obtained in step S4-2 to adjust the pH to 5 to 7, and then the solution is concentrated through a reverse osmosis membrane to obtain a concentrated solution. The lithium ion content in the concentrated solution is measured to be 3 g / L. The concentrated solution is evaporated to obtain a lithium ion mother liquor. The lithium ion content in the lithium ion mother liquor is measured to be 15 g / L.

[0187] Simultaneously, sodium hydroxide was added to the strontium ion concentrate obtained in step S1-2 to adjust the pH to 5 to 7, and then the concentrate was obtained by reverse osmosis membrane to obtain strontium ion mother liquor. The strontium ion content in the strontium ion mother liquor was measured to be 2.5 g / L.

[0188] S5-2. Sodium hydroxide is first added to the lithium-ion mother liquor obtained in step S5-1, and the mixture is stirred to produce magnesium hydroxide precipitate. After filtration, the filtrate is collected. Then sodium carbonate is added, and the mixture reacts to produce calcium carbonate precipitate. After filtration, the filtrate is collected, and sodium carbonate is added again to produce lithium carbonate solid. The content of calcium and magnesium in the lithium carbonate solid is 0, and the content of sodium is 2.8 wt%. The lithium carbonate solid is washed with hot water at a temperature higher than 90°C, then centrifuged, the lower precipitate is collected, and after drying, industrial-grade lithium carbonate is obtained. The purity is determined to be above 99.2%.

[0189] Simultaneously, strontium hydroxide was added to the strontium ion mother liquor obtained in step S5-1, and the reaction was carried out under stirring to produce magnesium hydroxide and calcium carbonate precipitates. After filtration, the filtrate was collected to obtain a purified strontium ion mother liquor, which was found to contain 2.2 g / L of strontium ions. Then, excess ammonium bicarbonate was added to the mother liquor, and the molar ratio of strontium ions to ammonium bicarbonate in the purified strontium ion mother liquor was 1:1.5. A metathesis reaction occurred at room temperature to produce strontium carbonate precipitate. After filtration, the filter residue was collected, washed, and dried to obtain strontium carbonate, which was found to have a purity of 99%. The filtrate obtained from filtration contained ammonium carbonate, which was collected by cooling and crystallization.

[0190] Example 2

[0191] This embodiment employs the cascade extraction method for associated resources in produced water provided by the present invention to perform cascade extraction of associated resources from produced water with a chloride ion concentration of not less than 2 g / L from an oilfield. The produced water was found to contain: lithium ions 65 mg / L, bromide ions 230 mg / L, bicarbonate ions 150 mg / L, strontium ions 40 mg / L, oil 2500 mg / L, suspended solids 110 mg / L, calcium ions 730 mg / L, and magnesium ions 55 mg / L.

[0192] (1) The equipment and raw material information involved in steps S1 to S5 are as follows:

[0193] Heat exchange electrolytic cell: a ruthenium-iridium coated titanium-based electrode is used as the anode and an iron electrode is used as the cathode; the anode and cathode dimensions are 1m*1m, a total of 10 pairs of anode-cathode are set, and the current is set to 2000A;

[0194] An ion exchange column filled with a first ion exchange resin: wherein the first ion exchange resin is ion exchange resin D001;

[0195] An ion exchange column filled with a second ion exchange resin: wherein the second ion exchange resin is a calcium-magnesium chelating resin;

[0196] Four sets of adsorption devices in parallel: fixed bed type, each set of adsorption devices includes four adsorption columns connected in series, each adsorption column is filled with 1200g of titanium-based adsorbent; wherein, the titanium-based adsorbent is metatitanic acid type adsorbent.

[0197] Reducing liquid: an aqueous solution of sulfur dioxide prepared by simultaneously introducing sulfur dioxide and water;

[0198] First acid solution: 1.6 wt% sulfuric acid aqueous solution;

[0199] Second acid solution: dilute hydrochloric acid with a pH of 1.5-2.0;

[0200] Third acid solution: 10wt% dilute hydrochloric acid;

[0201] Wash solution: water;

[0202] Alkaline solution: Sodium hydroxide aqueous solution, wherein the mass fraction of NaOH is 5 wt%.

[0203] (2) Figure 1 , Figure 2 As shown, using strontium ions as the target divalent ion and lithium ions as the target monovalent ion, the associated resources in the produced water are extracted in a cascade manner through the following steps:

[0204] First, the produced water is treated to remove oil and suspended solids, reducing the oil content to 45 mg / L and the suspended solids content to 31 mg / L. Then, the following steps S1 to S5 are performed.

[0205] S1. Through pre-separation treatment, the target divalent ions and target monovalent ions in the extracted water are separated to obtain concentrated water containing the target divalent ions, and tailings containing at least impurity divalent ions, bromide ions and target monovalent ions.

[0206] Specifically:

[0207] S1-1. Using the first ion exchange resin, target divalent ions are intercepted from the produced water to obtain concentrated tailings water;

[0208] The treated produced water, after being de-oiled and impurity removed, is passed into an ion exchange column filled with ion exchange resin D001. The ion exchange resin D001 selectively adsorbs strontium ions, thus retaining them in the produced water. Meanwhile, monovalent ions, including lithium ions such as bromide ions, as well as calcium and magnesium ions, are hardly selectively adsorbed by the ion exchange resin D001 and flow out of the ion exchange column, resulting in a reduced-concentration tailwater containing calcium, magnesium, bromide, and lithium ions.

[0209] S1-2. Elute the target divalent ions retained by the first ion exchange resin to obtain a concentrated solution of the target divalent ions;

[0210] Next, the ion exchange column filled with ion exchange resin D001 was sequentially washed with water and then rinsed with a 1.6 wt% sulfuric acid aqueous solution to elute the strontium ions retained on the ion exchange resin D001. The effluent was collected from the outlet of the ion exchange column, which is the strontium ion concentrate. The concentration of strontium ions in the strontium ion concentrate was measured to be 800 mg / L, calcium ions 55 mg / L, magnesium ions 6 mg / L, lithium ions 5 mg / L, and bicarbonate ions 150 mg / L.

[0211] S2. Remove divalent ions from the concentrated tailings water to obtain the target monovalent ion solution;

[0212] Specifically:

[0213] S2-1. Using a second ion exchange resin, divalent ions of impurities are intercepted from the concentrated tail water to obtain a solution of the target monovalent ion;

[0214] Specifically, the diluted tailwater obtained in step S1-1 is passed into an ion exchange column filled with calcium-magnesium chelating resin. Utilizing the selective adsorption of calcium and magnesium ions by the calcium-magnesium chelating resin, the calcium and magnesium ions in the diluted tailwater are retained, while monovalent ions such as lithium and bromide ions are hardly selectively adsorbed by the calcium-magnesium chelating resin. The tailwater flows out from the ion exchange column filled with calcium-magnesium chelating resin to obtain a lithium ion solution. The determination shows that the lithium ion solution obtained contains 52 mg / L of lithium ions, 5 mg / L of strontium ions, 70 mg / L of calcium ions, 5 mg / L of magnesium ions, and 150 mg / L of bicarbonate ions.

[0215] S2-2. To achieve continuous cascade extraction of associated resources from produced water, on the one hand, after collecting strontium ion concentrate, the ion exchange column filled with ion exchange resin D001 is first washed with water to remove residual sulfuric acid on the ion exchange resin D001, and then rinsed with 5wt% sodium hydroxide aqueous solution to achieve the transformation of ion exchange resin D001. Finally, it is washed with water to remove residual sodium hydroxide on the ion exchange resin D001, thereby regenerating the ion exchange resin D001 and enabling it to continue to selectively adsorb the strontium ions.

[0216] On the other hand, after the lithium ion solution is collected, when the selective adsorption of calcium and magnesium ions by the calcium-magnesium chelate resin in the ion exchange column filled with calcium-magnesium chelate resin reaches the adsorption endpoint, the adsorption column filled with calcium-magnesium chelate resin is washed with water and eluted with 10wt% dilute hydrochloric acid to remove the calcium and magnesium ions retained on the calcium-magnesium chelate resin. Then, it is washed with water to remove the residual dilute hydrochloric acid on the calcium-magnesium chelate resin, and then eluted with 5wt% sodium hydroxide aqueous solution to realize the transformation of calcium-magnesium chelate resin. Finally, it is washed with water to remove the residual sodium hydroxide on the calcium-magnesium chelate resin, thereby regenerating the calcium-magnesium chelate resin so that it can continue to selectively adsorb calcium and magnesium ions.

[0217] S3. Electrolyze the target monovalent ion solution to extract bromine, obtaining liquid bromine and bromine extraction tail water;

[0218] Specifically:

[0219] S3-1. Electrolyze the lithium-ion solution obtained in step S2-1 to obtain an electrolyzed lithium-ion solution; the electrolyzed lithium-ion solution contains elemental bromine, chlorine gas and hydrogen gas.

[0220] A lithium-ion solution was passed into a heat exchange electrolytic cell for electrolysis to obtain an electrolyzed lithium-ion solution. During electrolysis, the residual free oil components in the lithium-ion solution were oxidized to 0.8 mg / L. Chloride ions were converted into chlorine gas by anodic oxidation, bromide ions were converted into elemental bromine by anodic oxidation and chlorine gas oxidation, and hydrogen ions were converted into hydrogen gas by cathode reduction. Elemental bromine, chlorine gas, and hydrogen gas dissolved or dispersed in the electrolyzed lithium-ion solution. The electrodes in the heat exchange electrolytic cell operated stably for more than 30 days. After electrolysis, the voltage between the anode and cathode was 5.05V (the initial voltage before electrolysis was 5V), and almost no scaling was observed on the electrode surface.

[0221] S3-2. Heating and electrolyzing the lithium-ion solution causes the elemental bromine in it to be converted into bromine gas, which escapes along with chlorine and hydrogen gas, resulting in a mixed gas and bromine extraction tail water;

[0222] The temperature of the lithium-ion solution obtained after electrolysis in step S3-1 is heated to 20°C, where the elemental bromine is converted into bromine gas, which escapes along with chlorine and hydrogen gas, resulting in a mixed gas including bromine, chlorine and hydrogen, as well as bromine extraction tail water. The bromine extraction tail water was determined to contain: lithium ions 52 mg / L, strontium ions 5 mg / L, calcium ions 70 mg / L, magnesium ions 5 mg / L, and bicarbonate ions 140 mg / L.

[0223] S3-3. Bromine gas is obtained by separation and purification from the mixed gas through reduction with reducing liquid and oxidative distillation;

[0224] The sulfur dioxide aqueous solution is reacted with bromine and chlorine in the mixed gas obtained in step S3-2. The bromine and chlorine are reduced to hydrogen bromide and hydrogen chloride respectively by the bisulfite ions in the sulfur dioxide aqueous solution, resulting in a gas-liquid mixture containing hydrogen chloride, hydrogen bromide and hydrogen.

[0225] The obtained gas-liquid mixture was subjected to gas-liquid separation to obtain a mixed solution of hydrogen chloride and hydrogen bromide.

[0226] The obtained hydrogen chloride-hydrogen bromide mixed solution is subjected to oxidative distillation, specifically: the hydrogen chloride-hydrogen bromide mixed solution flows into the distillation column from the top, while chlorine gas and water vapor flow into the distillation column from the bottom. The chlorine gas oxidizes the bromide to elemental bromine on the packing material inside the distillation column; then, the generated elemental bromine is converted into bromine gas by steam distillation.

[0227] S3-4. Heat exchange is performed between bromine gas and the electrolyzed lithium-ion solution. Heating the electrolyzed lithium-ion solution causes the bromine gas to cool down, resulting in liquid bromine.

[0228] The bromine gas obtained from distillation in step S3-3 is exchanged with the lithium-ion solution after electrolysis for heat exchange. The heat carried by the bromine gas is used to heat the lithium-ion solution after electrolysis, raising its temperature to 20°C. During this process, the bromine gas is converted into liquid bromine due to the decrease in temperature. The purity of the liquid bromine is measured to be 91%.

[0229] S4. Extract the target monovalent ion from the target monovalent ion solution by adsorption / desorption to obtain a target monovalent ion-rich desorption solution, wherein the concentration of the target monovalent ion is not less than 0.2 g / L;

[0230] Specifically:

[0231] S4-1. The bromine extraction tail water obtained in step S3-2 is passed into four sets of adsorption devices connected in parallel at a flow rate of 35 mL / min for lithium ion adsorption. After the adsorption devices have been running stably for 1 hour, the adsorption tail liquids flowing out of the four sets of adsorption devices are collected and combined. The lithium ion content in the adsorption tail liquid is measured to be reduced to 30 mg / L. According to the average lithium ion content in the adsorption tail liquid after the adsorption devices have been running stably for 24 hours, it is 25 mg / L. The adsorption recovery rate of lithium ions by the adsorption devices can be calculated to be 52%.

[0232] S4-2. Water is passed into the adsorption unit at a flow rate of 70 mL / min for one impurity removal rinse. Then, acid is circulated to the four adsorption units at a flow rate of 70 mL / min for concentration and desorption.

[0233] Dilute hydrochloric acid was introduced into the first adsorption unit at a flow rate of 70 mL / min (or desorption flow rate) to perform one surface desorption, desorbing the lithium ions adsorbed on the surface of the titanium adsorbent in each adsorption column of the first adsorption unit. The first-stage desorption liquid was collected at the outlet of the first adsorption unit. Water was then introduced into the first adsorption unit at a flow rate of 140 mL / min to perform three internal pore rinsings, migrating the residual lithium ions in the internal pores of the titanium adsorbent. The rinsing liquid generated from each internal pore rinsing was collected at the outlet of the first adsorption unit.

[0234] The dilute hydrochloric acid and the eluent generated from the first internal pore rinsing of the first adsorption unit were combined (the combined pH was in the range of 1.5-2.0) and then introduced into the second adsorption unit at a flow rate of 70 mL / min for one surface desorption, desorbing the lithium ions adsorbed on the surface of the titanium adsorbent in each adsorption column of the second adsorption unit. The second-stage desorption liquid was collected at the outlet of the second adsorption unit. The eluent generated from the second and third internal pore rinsing of the first adsorption unit was introduced into the second adsorption unit at a flow rate of 140 mL / min for two internal pore rinsings, respectively, to migrate the residual lithium ions in the internal pores of the titanium adsorbent. The eluent generated from each internal pore rinsing was collected at the outlet of the second adsorption unit.

[0235] The dilute hydrochloric acid and the eluent generated from the first internal pore rinsing of the second adsorption unit were combined (the combined pH was in the range of 1.5-2.0) and then introduced into the third adsorption unit at a flow rate of 70 mL / min for one surface desorption. This desorbed the lithium ions adsorbed on the surface of the titanium-based adsorbent in each adsorption column of the third adsorption unit, and the third-stage desorption liquid was collected at the outlet of the third adsorption unit. The eluent generated from the second internal pore rinsing of the second adsorption unit was then introduced into the third adsorption unit at a flow rate of 140 mL / min for one internal pore rinsing. This migrated the residual lithium ions in the internal pores of the titanium-based adsorbent, and the eluent generated from the internal pore rinsing was collected at the outlet of the third adsorption unit.

[0236] The dilute hydrochloric acid and the eluent generated from the first internal pore rinsing of the third adsorption unit were combined (the combined pH was in the range of 1.5-2.0) and then introduced into the fourth adsorption unit at a flow rate of 70 mL / min for one surface desorption, desorbing the lithium ions adsorbed on the surface of the titanium-based adsorbent in each adsorption column of the fourth adsorption unit. The fourth-stage desorption liquid was collected at the outlet of the fourth adsorption unit. Water was then introduced into the fourth adsorption unit at a flow rate of 140 mL / min for one internal pore rinsing, and the eluent generated from the internal pore rinsing was collected at the outlet of the fourth adsorption unit. The eluent was then combined with the adsorption tail liquid obtained in step S4-1.

[0237] The first-stage desorption solution was combined with the fourth-stage desorption solution to obtain a lithium-rich desorption solution. The concentrations of lithium ions, calcium ions, magnesium ions, strontium ions, and bicarbonate ions in the lithium-rich desorption solution were measured to be 1 g / L, 20 mg / L, 1 mg / L, 1 mg / L, and 1 mg / L, respectively.

[0238] S5. Recover the target monovalent ions and target divalent ions from the target monovalent ion-rich desorption solution and the target divalent ion-rich concentrate, respectively;

[0239] Specifically,

[0240] S5-1. Sodium hydroxide is added to the lithium-rich desorption solution obtained in step S4-2 to adjust the pH to 5 to 7, and then the solution is concentrated through a reverse osmosis membrane to obtain a concentrated solution. The lithium ion content in the concentrated solution is measured to be 3 g / L. The concentrated solution is evaporated to obtain a lithium ion mother liquor. The lithium ion content in the lithium ion mother liquor is measured to be 15 g / L.

[0241] Simultaneously, sodium hydroxide was added to the strontium ion concentrate obtained in step S1-2 to adjust the pH to 5 to 7, and then the concentrate was obtained by reverse osmosis membrane to obtain strontium ion mother liquor. The strontium ion content in the strontium ion mother liquor was measured to be 2.5 g / L.

[0242] S5-2. Sodium hydroxide is first added to the lithium-ion mother liquor obtained in step S5-1, and the mixture is stirred to produce magnesium hydroxide precipitate. After filtration, the filtrate is collected. Then sodium carbonate is added, and the mixture reacts to produce calcium carbonate precipitate. After filtration, the filtrate is collected, and sodium carbonate is added again to produce lithium carbonate solid. The content of calcium and magnesium in the lithium carbonate solid is 0, and the content of sodium is 2.8 wt%. The lithium carbonate solid is washed with hot water at a temperature higher than 90°C, then centrifuged, the lower precipitate is collected, and after drying, industrial-grade lithium carbonate is obtained. The purity is determined to be above 99.2%.

[0243] Simultaneously, strontium hydroxide was added to the strontium ion mother liquor obtained in step S5-1, and the reaction was carried out under stirring to produce magnesium hydroxide and calcium carbonate precipitates. After filtration, the filtrate was collected to obtain a purified strontium ion mother liquor, which was found to contain 2.2 g / L of strontium ions. Then, excess ammonium bicarbonate was added to the mother liquor, and the molar ratio of strontium ions to ammonium bicarbonate in the purified strontium ion mother liquor was 1:1.5. A metathesis reaction occurred at room temperature to produce strontium carbonate precipitate. After filtration, the filter residue was collected, washed, and dried to obtain strontium carbonate, which was found to have a purity of 99%. The filtrate obtained from filtration contained ammonium carbonate, which was collected by cooling and crystallization.

[0244] Comparative Example 1

[0245] This comparative example involves the extraction of associated resources from the same produced water as in Example 2.

[0246] (1) Information on the apparatus and raw materials involved: No second ion exchange resin and corresponding ion exchange column filled with second ion exchange resin are used; no third acid solution is used; otherwise, it is the same as in Example 2.

[0247] (2) Using strontium ions as the target divalent ion and lithium ions as the target monovalent ion, the associated resources are extracted from the produced water through the following steps:

[0248] First, the produced water is treated to remove oil and suspended solids, and the treatment results are the same as in Example 2; then the following steps are performed.

[0249] Part 1: Lithium Extraction and Recovery

[0250] Step 1-1. The extracted water is passed into four sets of adsorption devices connected in parallel at a flow rate of 35 mL / min for lithium ion adsorption. After the adsorption devices have been running stably for 1 hour, the adsorption tail liquids flowing out of the four sets of adsorption devices are collected and combined. The lithium ion content in the adsorption tail liquid is measured to be reduced to 30 mg / L. According to the average lithium ion content in the adsorption tail liquid after the adsorption devices have been running stably for 24 hours, it is 25 mg / L. The adsorption recovery rate of lithium ions by the adsorption devices can be calculated to be 52%.

[0251] Steps 1-2. First, rinse the adsorption unit with water at a flow rate of 70 mL / min to remove impurities. Then, perform segmented circulation concentrating and desorption on the four adsorption units at a flow rate of 70 mL / min.

[0252] Dilute hydrochloric acid was introduced into the first adsorption unit at a flow rate of 70 mL / min (or desorption flow rate) to perform one surface desorption, desorbing the lithium ions adsorbed on the surface of the titanium adsorbent in each adsorption column of the first adsorption unit. The first-stage desorption liquid was collected at the outlet of the first adsorption unit. Water was then introduced into the first adsorption unit at a flow rate of 140 mL / min to perform three internal pore rinsings, migrating the residual lithium ions in the internal pores of the titanium adsorbent. The rinsing liquid generated from each internal pore rinsing was collected at the outlet of the first adsorption unit.

[0253] The dilute hydrochloric acid and the eluent generated from the first internal pore rinsing of the first adsorption unit were combined (the combined pH was in the range of 1.5-2.0) and then introduced into the second adsorption unit at a flow rate of 70 mL / min for one surface desorption, desorbing the lithium ions adsorbed on the surface of the titanium adsorbent in each adsorption column of the second adsorption unit. The second-stage desorption liquid was collected at the outlet of the second adsorption unit. The eluent generated from the second and third internal pore rinsing of the first adsorption unit was introduced into the second adsorption unit at a flow rate of 140 mL / min for two internal pore rinsings, respectively, to migrate the residual lithium ions in the internal pores of the titanium adsorbent. The eluent generated from each internal pore rinsing was collected at the outlet of the second adsorption unit.

[0254] The dilute hydrochloric acid and the eluent generated from the first internal pore rinsing of the second adsorption unit were combined (the combined pH was in the range of 1.5-2.0) and then introduced into the third adsorption unit at a flow rate of 70 mL / min for one surface desorption. This desorbed the lithium ions adsorbed on the surface of the titanium-based adsorbent in each adsorption column of the third adsorption unit, and the third-stage desorption liquid was collected at the outlet of the third adsorption unit. The eluent generated from the second internal pore rinsing of the second adsorption unit was then introduced into the third adsorption unit at a flow rate of 140 mL / min for one internal pore rinsing. This migrated the residual lithium ions in the internal pores of the titanium-based adsorbent, and the eluent generated from the internal pore rinsing was collected at the outlet of the third adsorption unit.

[0255] The dilute hydrochloric acid and the eluent generated from the first internal pore rinsing of the third adsorption unit were combined (the combined pH was in the range of 1.5-2.0) and then introduced into the fourth adsorption unit at a flow rate of 70 mL / min for one surface desorption, desorbing the lithium ions adsorbed on the surface of the titanium-based adsorbent in each adsorption column of the fourth adsorption unit. The fourth-stage desorption liquid was collected at the outlet of the fourth adsorption unit. Water was then introduced into the fourth adsorption unit at a flow rate of 140 mL / min for one internal pore rinsing, and the eluent generated from the internal pore rinsing was collected at the outlet of the fourth adsorption unit. The eluent was then combined with the adsorption tail liquid obtained in step S4-1.

[0256] The first-stage desorption solution was combined with the fourth-stage desorption solution to obtain a lithium-rich desorption solution. The concentrations of lithium ions, calcium ions, magnesium ions, strontium ions, and bicarbonate ions in the lithium-rich desorption solution were measured to be 1 g / L, 130 mg / L, 6 mg / L, 10 mg / L, and 1 mg / L, respectively.

[0257] Steps 1-3. Add sodium hydroxide to the lithium-rich desorption solution obtained in step 1-2 to adjust the pH to 5 to 7, and then concentrate it through a reverse osmosis membrane to obtain a concentrated solution; the lithium ion content in the concentrated solution is measured to be 3 g / L; evaporate the concentrated solution to obtain a lithium ion mother liquor, and the lithium ion content in the lithium ion mother liquor is measured to be 15 g / L.

[0258] Steps 1-4. Sodium hydroxide is first added to the lithium-ion mother liquor obtained in Step 1-3, and the mixture is stirred to produce magnesium hydroxide precipitate. After filtration, the filtrate is collected. Then sodium carbonate is added, and the mixture reacts to produce calcium carbonate precipitate. After filtration, the filtrate is collected, and sodium carbonate is added again to produce lithium carbonate solid. The content of calcium and magnesium in the lithium carbonate solid is 0, and the content of sodium is 2.8 wt%. The lithium carbonate solid is washed with hot water at a temperature higher than 90°C, then centrifuged, the lower precipitate is collected, and after drying, industrial-grade lithium carbonate is obtained. The purity is determined to be above 99.2%.

[0259] Part Two: Strontium Extraction and Recovery

[0260] Step 2-1. Pass the adsorption tail liquid obtained in Step 1-1 into an ion exchange column filled with ion exchange resin D001. The ion exchange resin D001 is used to selectively adsorb strontium ions. The deconcentrated adsorption tail water is collected from the outlet of the ion exchange column. The concentration of lithium ions in the deconcentrated adsorption tail water is measured to be 55 mg / L, strontium ions 10 mg / L, calcium ions 700 mg / L, magnesium ions 50 mg / L, and bicarbonate ions 150 mg / L.

[0261] Step 2-2. Next, the ion exchange column filled with ion exchange resin D001 is washed with water and then rinsed with 1.6wt% sulfuric acid aqueous solution to elute the strontium ions retained on the ion exchange resin D001. The effluent is collected from the outlet of the ion exchange column, which is the strontium ion concentrate. The concentration of strontium ions in the strontium ion concentrate is measured to be 600 mg / L, calcium ions 45 mg / L, magnesium ions 5 mg / L, lithium ions 5 mg / L, and bicarbonate ions 1 mg / L.

[0262] Steps 2-3. After collecting the strontium ion concentrate, the ion exchange column filled with ion exchange resin D001 is first washed with water to remove residual sulfuric acid on the ion exchange resin D001, and then rinsed with a 5wt% sodium hydroxide aqueous solution to achieve the transformation of ion exchange resin D001. Finally, it is washed with water to remove residual sodium hydroxide on the ion exchange resin D001, thereby regenerating the ion exchange resin D001 so that it can continue to selectively adsorb the strontium ions.

[0263] Step 2-4. Add sodium hydroxide to the strontium ion concentrate obtained in step 2-2 to adjust the pH to 5 to 7, and then concentrate it through a reverse osmosis membrane to obtain strontium ion mother liquor. The strontium ion content in the strontium ion mother liquor is measured to be 2.5 g / L.

[0264] Steps 2-5. Strontium hydroxide is added to the strontium ion mother liquor obtained in Step 2-4. The reaction is carried out under stirring to produce magnesium hydroxide and calcium carbonate precipitates. After filtration, the filtrate is collected to obtain purified strontium ion mother liquor, which is found to contain 2.2 g / L of strontium ions. Then, excess ammonium bicarbonate is added to the mother liquor, so that the molar ratio of strontium ions to ammonium bicarbonate in the purified strontium ion mother liquor is 1:1.5. A metathesis reaction occurs at room temperature to produce strontium carbonate precipitate. After filtration, the filter residue is collected, washed, and dried to obtain strontium carbonate, which is found to have a purity of 99%. The filtrate obtained from filtration contains ammonium carbonate, which is collected by cooling and crystallization.

[0265] Part Three: Extraction and Recovery of Bromine

[0266] Step 3-1. The diluted adsorption tailwater obtained in Step 2-1 is fed into a heat exchange electrolytic cell for electrolysis to obtain diluted adsorption tailwater containing bromine, chlorine, and hydrogen. During electrolysis, the residual free oil component in the diluted adsorption tailwater is oxidized to 0.8 mg / L. Chloride ions are converted to chlorine by anodic oxidation, bromide ions are converted to bromine by anodic oxidation and chlorine oxidation, and hydrogen ions are converted to hydrogen by cathode reduction. Bromine, chlorine, and hydrogen dissolve or disperse in the lithium-ion solution after electrolysis. The stable operating time of the electrodes in the heat exchange electrolytic cell does not exceed 10 days. After electrolysis, the voltage between the cathode and anode is 7.5V (the initial voltage before electrolysis is 5V), and the voltage rises by more than 1.2 times after electrolysis. Severe scaling is observed on the electrode surface.

[0267] Step 3-2. The temperature of the electrolytically concentrated adsorption tailwater obtained in Step 3-1 is heated to 65℃, where the elemental bromine is converted into bromine gas, which escapes along with chlorine and hydrogen gas, resulting in a mixed gas including bromine, chlorine and hydrogen, as well as bromine extraction tailwater. The bromine extraction tailwater contains the following components: lithium ions 52 mg / L, strontium ions 5 mg / L, calcium ions 630 mg / L, magnesium ions 45 mg / L, and bicarbonate ions 140 mg / L.

[0268] Step 3-3. React the sulfur dioxide aqueous solution with the bromine and chlorine in the mixed gas obtained in Step 3-2. Use the bisulfite ions in the sulfur dioxide aqueous solution to reduce the bromine and chlorine to hydrogen bromide and hydrogen chloride, respectively, to obtain a gas-liquid mixture containing hydrogen chloride, hydrogen bromide and hydrogen.

[0269] The obtained gas-liquid mixture was subjected to gas-liquid separation to obtain a mixed solution of hydrogen chloride and hydrogen bromide.

[0270] The obtained hydrogen chloride-hydrogen bromide mixed solution is subjected to oxidative distillation, specifically: the hydrogen chloride-hydrogen bromide mixed solution flows into the distillation column from the top, while chlorine gas and water vapor flow into the distillation column from the bottom. The chlorine gas oxidizes the bromide to elemental bromine on the packing material inside the distillation column; then, the generated elemental bromine is converted into bromine gas by steam distillation.

[0271] Step 3-4. The bromine gas obtained from distillation in step 3-3 is exchanged with the lithium ion solution after electrolysis. The heat carried by the bromine gas is used to heat the concentrated adsorption tail water after electrolysis, raising the temperature of the concentrated adsorption tail water to 20°C. During this process, the bromine gas is converted into liquid bromine due to the decrease in temperature. The purity of the liquid bromine is measured to be 91%.

[0272] Comparative Example 2

[0273] This comparative example involves the extraction of associated resources from the same produced water as in Example 2.

[0274] (1) Information on the apparatus and raw materials involved: No second ion exchange resin and corresponding ion exchange column filled with second ion exchange resin are used; no third acid solution is used; otherwise, it is the same as in Example 2.

[0275] (2) Figure 1 As shown, using strontium ions as the target divalent ion and lithium ions as the target monovalent ion, the associated resources are extracted from the produced water through the following steps:

[0276] First, the produced water is treated to remove oil and suspended solids, and the treatment results are the same as in Example 2; then the following steps are performed.

[0277] Part 1: Extraction and Recovery of Bromine

[0278] Step 1-1. The produced water is fed into a heat exchange electrolytic cell for electrolysis to obtain electrolyzed produced water containing elemental bromine, chlorine, and hydrogen. During electrolysis, the residual free oil components in the produced water are oxidized to 0.8 mg / L. Chloride ions are converted to chlorine gas through anodic oxidation, bromide ions are converted to elemental bromine through anodic oxidation and chlorine oxidation, and hydrogen ions are converted to hydrogen gas through cathode reduction. Elemental bromine, chlorine, and hydrogen dissolve or disperse in the electrolyzed produced water. The stable operating time of the electrodes in the heat exchange electrolytic cell does not exceed 10 days. After electrolysis, the voltage between the cathode and anode is 7V (the initial voltage before electrolysis is 5V), and the voltage rises by more than 1.2 times after electrolysis. Severe scaling is observed on the electrode surface.

[0279] Step 1-2. The temperature of the electrolyzed water obtained in Step 1-1 is heated to 20°C, where the elemental bromine is converted into bromine gas, which escapes along with chlorine and hydrogen gas, resulting in a mixed gas containing bromine, chlorine and hydrogen, as well as bromine extraction tail water. The bromine extraction tail water is found to contain: lithium ions 55 mg / L, strontium ions 40 mg / L, calcium ions 660 mg / L, magnesium ions 50 mg / L, and bicarbonate ions 140 mg / L.

[0280] Steps 1-3. React the sulfur dioxide aqueous solution with the bromine and chlorine in the mixed gas obtained in Step 1-2. Use the bisulfite ions in the sulfur dioxide aqueous solution to reduce the bromine and chlorine to hydrogen bromide and hydrogen chloride, respectively, to obtain a gas-liquid mixture containing hydrogen chloride, hydrogen bromide and hydrogen.

[0281] The obtained gas-liquid mixture was subjected to gas-liquid separation to obtain a mixed solution of hydrogen chloride and hydrogen bromide.

[0282] The obtained hydrogen chloride-hydrogen bromide mixed solution is subjected to oxidative distillation, specifically: the hydrogen chloride-hydrogen bromide mixed solution flows into the distillation column from the top, while chlorine gas and water vapor flow into the distillation column from the bottom. The chlorine gas oxidizes the bromide to elemental bromine on the packing material inside the distillation column; then, the generated elemental bromine is converted into bromine gas by steam distillation.

[0283] Steps 1-4. The bromine gas obtained from distillation in Step 1-3 is exchanged with the electrolyzed water for heat exchange. The heat carried by the bromine gas is used to heat the electrolyzed water, raising its temperature to 20°C. During this process, the bromine gas is converted into liquid bromine due to the decrease in temperature. The purity of the liquid bromine is measured to be 91%.

[0284] Part Two: Lithium Extraction and Recovery

[0285] Step 2-1. The bromine extraction tail water obtained in Step 1-2 is passed into four sets of adsorption devices connected in parallel at a flow rate of 35 mL / min for lithium ion adsorption. After the adsorption devices have been running stably for 1 hour, the adsorption tail liquids flowing out of the four sets of adsorption devices are collected and combined. The lithium ion content in the adsorption tail liquid is measured to be reduced to 30 mg / L. According to the average lithium ion content in the adsorption tail liquid after the adsorption devices have been running stably for 24 hours, it is 25 mg / L. Therefore, the adsorption recovery rate of lithium ions by the adsorption devices can be calculated to be 52%.

[0286] Step 2-2. Water is passed into the adsorption unit at a flow rate of 70 mL / min for one impurity removal rinse. Then, acid is circulated to the four adsorption units at a flow rate of 70 mL / min for concentration and desorption.

[0287] Dilute hydrochloric acid was introduced into the first adsorption unit at a flow rate of 70 mL / min (or desorption flow rate) to perform one surface desorption, desorbing the lithium ions adsorbed on the surface of the titanium adsorbent in each adsorption column of the first adsorption unit. The first-stage desorption liquid was collected at the outlet of the first adsorption unit. Water was then introduced into the first adsorption unit at a flow rate of 140 mL / min to perform three internal pore rinsings, migrating the residual lithium ions in the internal pores of the titanium adsorbent. The rinsing liquid generated from each internal pore rinsing was collected at the outlet of the first adsorption unit.

[0288] The dilute hydrochloric acid and the eluent generated from the first internal pore rinsing of the first adsorption unit were combined (the combined pH was in the range of 1.5-2.0) and then introduced into the second adsorption unit at a flow rate of 70 mL / min for one surface desorption, desorbing the lithium ions adsorbed on the surface of the titanium adsorbent in each adsorption column of the second adsorption unit. The second-stage desorption liquid was collected at the outlet of the second adsorption unit. The eluent generated from the second and third internal pore rinsing of the first adsorption unit was introduced into the second adsorption unit at a flow rate of 140 mL / min for two internal pore rinsings, respectively, to migrate the residual lithium ions in the internal pores of the titanium adsorbent. The eluent generated from each internal pore rinsing was collected at the outlet of the second adsorption unit.

[0289] The dilute hydrochloric acid and the eluent generated from the first internal pore rinsing of the second adsorption unit were combined (the combined pH was in the range of 1.5-2.0) and then introduced into the third adsorption unit at a flow rate of 70 mL / min for one surface desorption. This desorbed the lithium ions adsorbed on the surface of the titanium-based adsorbent in each adsorption column of the third adsorption unit, and the third-stage desorption liquid was collected at the outlet of the third adsorption unit. The eluent generated from the second internal pore rinsing of the second adsorption unit was then introduced into the third adsorption unit at a flow rate of 140 mL / min for one internal pore rinsing. This migrated the residual lithium ions in the internal pores of the titanium-based adsorbent, and the eluent generated from the internal pore rinsing was collected at the outlet of the third adsorption unit.

[0290] The dilute hydrochloric acid and the eluent generated from the first internal pore rinsing of the third adsorption unit were combined (the combined pH was in the range of 1.5-2.0) and then introduced into the fourth adsorption unit at a flow rate of 70 mL / min for one surface desorption, desorbing the lithium ions adsorbed on the surface of the titanium-based adsorbent in each adsorption column of the fourth adsorption unit. The fourth-stage desorption liquid was collected at the outlet of the fourth adsorption unit. Water was then introduced into the fourth adsorption unit at a flow rate of 140 mL / min for one internal pore rinsing, and the eluent generated from the internal pore rinsing was collected at the outlet of the fourth adsorption unit. This eluent was then combined with the adsorption tail liquid obtained in step 2-1.

[0291] The first-stage desorption solution was combined with the fourth-stage desorption solution to obtain a lithium-rich desorption solution. The concentrations of lithium ions, calcium ions, magnesium ions, strontium ions, and bicarbonate ions in the lithium-rich desorption solution were measured to be 1 g / L, 130 mg / L, 6 mg / L, 10 mg / L, and 1 mg / L, respectively.

[0292] Step 2-3. Add sodium hydroxide to the lithium-rich desorption solution obtained in step 2-2 to adjust the pH to 5 to 7, and then concentrate it through a reverse osmosis membrane to obtain a concentrated solution; the lithium ion content in the concentrated solution is measured to be 3 g / L; evaporate the concentrated solution to obtain a lithium ion mother liquor, and the lithium ion content in the lithium ion mother liquor is measured to be 15 g / L.

[0293] Steps 2-4. Sodium hydroxide is first added to the lithium-ion mother liquor obtained in step 2-3, and the mixture is stirred to produce magnesium hydroxide precipitate. After filtration, the filtrate is collected. Then sodium carbonate is added, and the mixture reacts to produce calcium carbonate precipitate. After filtration, the filtrate is collected, and sodium carbonate is added again to produce lithium carbonate solid. The content of calcium and magnesium in the lithium carbonate solid is 0, and the content of sodium is 2.8 wt%. The lithium carbonate solid is washed with hot water at a temperature higher than 90°C, then centrifuged, the lower precipitate is collected, and after drying, industrial-grade lithium carbonate is obtained. The purity is determined to be above 99.2%.

[0294] Part Three: Strontium Extraction and Recovery

[0295] Step 3-1. Pass the adsorption tail liquid obtained in Step 2-1 into an ion exchange column filled with ion exchange resin D001. Use ion exchange resin D001 to selectively adsorb strontium ions. Collect the deconcentrated adsorption tail water from the outlet of the ion exchange column.

[0296] Step 3-2. Next, the ion exchange column filled with ion exchange resin D001 is washed with water and then rinsed with 1.6wt% sulfuric acid aqueous solution to elute the strontium ions retained on the ion exchange resin D001. The effluent is collected from the outlet of the ion exchange column, which is the strontium ion concentrate. The concentration of strontium ions in the strontium ion concentrate is measured to be 800 mg / L, calcium ions 55 mg / L, magnesium ions 6 mg / L, lithium ions 5 mg / L, and bicarbonate ions 150 mg / L.

[0297] Step 3-3. After collecting the strontium ion concentrate, the ion exchange column filled with ion exchange resin D001 is first washed with water to remove residual sulfuric acid on the ion exchange resin D001, and then rinsed with 5wt% sodium hydroxide aqueous solution to achieve the transformation of ion exchange resin D001. Finally, it is washed with water to remove residual sodium hydroxide on the ion exchange resin D001, thereby regenerating the ion exchange resin D001 so that it can continue to selectively adsorb the strontium ions.

[0298] Step 3-4. Sodium hydroxide is added to the strontium ion concentrate obtained in step 3-2 to adjust the pH to 5 to 7. Then, the concentrate is obtained by passing it through a reverse osmosis membrane to obtain a strontium ion mother liquor. The strontium ion content in the strontium ion mother liquor is measured to be 2.5 g / L.

[0299] Steps 3-5. Strontium hydroxide is added to the strontium ion mother liquor obtained in step 3-4. The reaction is carried out under stirring to produce magnesium hydroxide and calcium carbonate precipitates. After filtration, the filtrate is collected to obtain purified strontium ion mother liquor, which is found to contain 2.2 g / L of strontium ions. Then, excess ammonium bicarbonate is added to the mother liquor, so that the molar ratio of strontium ions to ammonium bicarbonate in the purified strontium ion mother liquor is 1:1.5. A metathesis reaction occurs at room temperature to produce strontium carbonate precipitate. After filtration, the filter residue is collected, washed, and dried to obtain strontium carbonate, which is found to have a purity of 99%. The filtrate obtained after filtration contains ammonium carbonate, which is collected by cooling and crystallization.

[0300] Results Evaluation

[0301] The ion concentration information of key fluids such as lithium ion desorption fluid during the extraction of associated resources from produced water in Examples 1 and 2 and Comparative Examples 1 and 2 is summarized in Table 1.

[0302] Table 1. Concentration of various ions in key fluids during the extraction process of associated resources from produced water

[0303]

[0304]

[0305] As shown in Table 1, compared with Example 2, Comparative Examples 1 and 2 changed the extraction order of associated resources in the produced water and did not perform pre-separation treatment or removal of calcium and magnesium ions. Specifically, Comparative Example 1 did not perform pre-separation treatment to initially separate strontium, nor did it remove calcium and magnesium ions; it directly extracted in the lithium-strontium-bromine order. The resulting lithium-rich desorption solution had a calcium ion content as high as 130 mg / L and a strontium ion content of 10 mg / L. The excessively high content of divalent ions exacerbated the extraction of lithium-rich resources. The lithium ion desorption solution has a heavy burden of impurity removal during the conversion of lithium ions into lithium carbonate products; the strontium ion concentration in the resulting strontium ion concentrate is reduced to 600 mg / L; the calcium ion concentration in the resulting deconcentrated adsorption tail water is significantly increased to 700 mg / L, and the magnesium ion concentration is also 50 mg / L. As the feed water for electrolytic bromine extraction, the presence of a large amount of calcium and magnesium ions leads to significant scaling on the electrode surface during electrolysis, causing the electrode voltage to rise by more than 1.2 times the initial voltage, which affects the stable operation and service life of the electrolysis device. Comparative Example 2 did not perform pre-separation treatment to initially separate strontium, nor did it remove calcium and magnesium ions. It directly extracted strontium in the order of bromine-lithium-strontium. The extracted water was used as the feed water for electrolytic bromine extraction. The calcium ion content was as high as 730 mg / L and the magnesium ion content was as high as 55 mg / L. This caused a large amount of calcium and magnesium ions to form scale on the electrode surface during electrolysis, resulting in an increase in electrode voltage of more than 1.2 times the initial voltage, which affected the stable operation and service life of the electrolysis device. The calcium ion content in the bromine extraction tail water after electrolysis was still as high as 660 mg / L and the magnesium ion content was as high as 50 mg / L. The lithium-rich desorption solution obtained after lithium adsorption / desorption of the feed water also contained a large amount of calcium ions (calcium ion content of 130 mg / L), which increased the impurity removal pressure in the process of converting lithium ions in the lithium-rich desorption solution into lithium carbonate products.

[0306] In the process of extracting associated resources from the produced water in Examples 1 and 2, following a specific extraction sequence, strontium ions were first pre-separated to remove calcium and magnesium ions, followed by electrolytic bromine extraction and lithium separation. The resulting strontium ion concentrate had a strontium ion content as high as 800 mg / L, a calcium ion content as low as 55 mg / L, and a magnesium ion content as low as 6 mg / L, thus avoiding interference from the large presence of calcium and magnesium ions in strontium ion extraction. The resulting lithium ion solution had a very low calcium and magnesium ion content, which, when used as feed water for electrolytic bromine extraction, prevented the large-scale scaling of calcium and magnesium ions on the electrodes during electrolysis, thus avoiding impact on the operational safety and service life of the electrolysis equipment. The resulting bromine tail water also had a very low calcium and magnesium ion content, which, when used as feed water for lithium extraction, prevented interference from the large presence of calcium and magnesium ions in lithium adsorption and extraction. The resulting lithium-rich desorption solution had a lithium ion content as high as 1000 mg / L, a calcium and magnesium ion content as low as 20 mg / L, and a magnesium ion content as low as 1 mg / L.

[0307] While the present invention has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of the invention. Furthermore, numerous modifications can be made to the subject, spirit, and scope of the invention to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of the present invention.

Claims

1. A method for cascade extraction of associated resources from produced water, characterized in that, Includes the following steps: S1. Through pre-separation treatment, the target divalent ions and target monovalent ions in the extracted water are separated to obtain concentrated water containing the target divalent ions, and tailings containing at least impurity divalent ions, bromide ions and target monovalent ions. S2. Remove the divalent ions of impurities from the concentrated tailings water to obtain the target monovalent ion solution; S3. Electrolyze the target monovalent ion solution to extract bromine, obtaining liquid bromine and bromine extraction tail water; S4. Extract the target monovalent ion from the bromine extraction tailwater by adsorption / desorption to obtain a target monovalent ion-rich desorption solution, wherein the concentration of the target monovalent ion is not less than 0.2 g / L and the concentration of the impurity divalent ion is not higher than 3% of the initial concentration of impurity divalent ions in the extracted water; S5. The target monovalent ion and the target divalent ion are recovered from the target monovalent ion-rich desorption solution and the target divalent ion-rich concentrate, respectively.

2. The method according to claim 1, characterized in that, In the target monovalent ion-rich desorption solution, the concentration of the target monovalent ion is not less than 1 g / L.

3. The method according to claim 2, characterized in that, The target divalent ion includes strontium ions; and / or the target monovalent ion includes lithium ions; and / or the impurity divalent ions include at least calcium ions and / or magnesium ions.

4. The method according to claim 3, characterized in that, In the target monovalent ion solution, the concentration of the target monovalent ion is not less than 90% of the initial concentration of the target monovalent ion in the produced water, the concentration of the target divalent ion is not more than 15% of the initial concentration of the target divalent ion in the produced water, and the concentration of the impurity divalent ion is not more than 10% of the initial concentration of the impurity divalent ion in the produced water; and / or In the target divalent ion concentrate, the concentration of the target divalent ion is not less than 800 mg / L, and the concentration of the impurity divalent ion is not more than 60 mg / L.

5. The method according to claim 4, characterized in that, In step S1, the target divalent ions are retained from the extracted water using a first ion exchange resin to obtain the reduced-concentration tailwater; the target divalent ions retained by the first ion exchange resin are eluted to obtain the target divalent ion concentrate. and / or In step S2, the second ion exchange resin is used to intercept the divalent impurity ions from the concentrated tailings water to obtain the target monovalent ion solution.

6. The method according to claim 5, characterized in that, The first ion exchange resin selectively adsorbs the target divalent ion; and / or The second ion exchange resin selectively adsorbs the divalent impurity ions.

7. The method according to claim 6, characterized in that, The first ion exchange resin is ion exchange resin D001 or ion exchange resin DJH003; and / or The second ion exchange resin is a calcium-magnesium chelating resin; Preferably, the target divalent ions retained on the first ion exchange resin are eluted by sequentially performing water washing and first acid rinsing. Preferably, the first acid solution is a 3-6 wt% aqueous solution of sulfuric acid.

8. The method according to any one of claims 1 to 7, characterized in that, In step S4, the bromine extraction tail water is passed through an adsorption device for selective adsorption of the target monovalent ions; after the adsorption device reaches the adsorption endpoint, desorption is performed to obtain the target monovalent ion-rich desorbent solution.

9. The method according to claim 8, characterized in that, The number of adsorption devices is n, where n is an integer ≥ 1; and / or The adsorption device is filled with a target monovalent ion selective adsorbent; Preferably, the target monovalent ion selective adsorbent includes any one of titanium-based adsorbents, manganese-based adsorbents, and aluminum-based adsorbents.

10. The method according to claim 9, characterized in that, The adsorption device is desorbed using a second acid solution or water. Preferably, the second acid solution comprises dilute hydrochloric acid with a pH of 1.5-2.

0.

11. The method according to claim 10, characterized in that, In step S5, the recovery of the target monovalent ion and the target divalent ion is carried out simultaneously.

12. The method according to claim 10 or 11, characterized in that, In step S5, the target monovalent ion is recovered as follows: The desorption solution rich in target monovalent ions is concentrated using a reverse osmosis membrane to obtain a concentrate, which is then evaporated to obtain a target monovalent ion mother liquor. A target monovalent ion precipitant is added to the target monovalent ion mother liquor to precipitate the target monovalent ions, thus completing the recovery of the target monovalent ions. Preferably, the concentration of the target monovalent ion in the concentrate is 2-5 g / L; and / or In the target monovalent ion mother liquor, the concentration of the target monovalent ion is 15-20 g / L.

13. The method according to claim 12, characterized in that, In step S5, the target divalent ion is recovered as follows: The target divalent ion concentrate is obtained by concentrating the water using a reverse osmosis membrane to obtain the target divalent ion mother liquor; the target divalent ion precipitant is added to the target divalent ion mother liquor to precipitate the target divalent ion, thereby completing the recovery of the target divalent ion; Preferably, the concentration of the target divalent ion in the target divalent ion mother liquor is 1-5 g / L.

14. The method according to claim 13, characterized in that, The target monovalent ion precipitant includes sodium carbonate; and / or the target divalent ion precipitant includes ammonium carbonate and / or ammonium bicarbonate.

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