Process and device for extracting associated resources from produced water

Abstract

The present invention relates to a process and device for extracting associated resources from produced water. First target ions are separated from other ions by means of a pre-separation treatment, and impurity ions are removed prior to the electrolysis of an electrolysis device. In this way, impurity ions such as calcium ions and magnesium ions can be prevented from scaling on an electrode during the process of electrolyzing second target ions, thereby improving the electrolysis efficiency and prolonging the effective runtime of the electrolysis device. Moreover, the process of adsorbing and desorbing third target ions by means of an enrichment and purification device is also prevented from the influence of the impurity ions such as calcium ions and magnesium ions. Therefore, the stepwise extraction of associated resources from produced water is achieved in a comprehensive and systematic manner by means of a relatively simple process flow and lower energy consumption, thereby maximally avoiding wasting the associated resources.

Description

Process and device for extracting associated resources from produced water

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 2024113508580, filed on September 26, 2024, entitled “A bicarbonate buffer type adsorption / desorption method and device”, Chinese Patent Application No. 2024113508595, filed on September 26, 2024, entitled “An adsorption / segmented cycle concentration-enhanced desorption method and device”, Chinese Patent Application No. 2024113508608, filed on September 26, 2024, entitled “A method for gradient extraction of associated resources from produced water”, and Chinese Patent Application No. 2024113508612, filed on September 26, 2024, entitled “A bromine extraction device for oilfield produced water”, the entire contents of which are hereby incorporated by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of resource extraction, in particular to a process and device for extracting associated resources from produced water. BACKGROUND

[0004] There are a large amount of associated resources in natural water bodies such as seawater, salt lake water, and produced water during oil and gas extraction, such as lithium, sodium, potassium, strontium, and other metal resources, as well as bromine, iodine, and other non-metal resources. In non-natural water bodies such as industrial wastewater and domestic wastewater, these resources may also exist.

[0005] Currently, there are few processes or methods for comprehensive extraction of water bodies rich in resources. On the one hand, due to the large differences in resource types and grades in different water bodies, the processes or methods for extracting associated resources from water bodies also have large differences. Moreover, some processes have the problems of long process flow, complicated process, high energy consumption, etc. On the other hand, current extraction of associated resources from water bodies is mainly for single resources. For example, single resources are extracted from oilfield produced water, while other unextracted resources remain with the produced water for reinjection, resulting in a large waste of resources. SUMMARY

[0006] Based on the above problems in the prior art, the present application provides a process and device for extracting associated resources from produced water, which comprehensively and integrally extracts associated resources from produced water through a relatively simple process flow and lower energy consumption, to maximize the avoidance of waste of associated resources.

[0007] According to a first aspect of the present application, there is provided a process for extracting associated resources from produced water, comprising subjecting a produced water sample to a multi-stage enrichment purification process for a final target ion, wherein in each stage of the enrichment purification process: subjecting the produced water sample to an adsorption operation for the final target ion using an adsorbent, subjecting the adsorbent to one primary desorption to obtain and store a first liquid stream, and subjecting the adsorbent to a plurality of secondary desorptions to obtain a plurality of second liquid streams for use in the primary and secondary desorptions of the next stage of the enrichment purification process.

[0008] Further, the number of secondary desorptions in the next stage of the enrichment purification process is less than the number of secondary desorptions in the previous stage of the enrichment purification process, until no secondary desorption is performed in the last stage of the enrichment purification process.

[0009] Further, the produced water sample is subjected to n stages of enrichment purification, where n is an integer greater than or equal to 3, and in the i-th stage of enrichment purification, the adsorbent is subjected to n-i secondary desorptions, where i is an integer from 1 to n.

[0010] Further, in the first stage of enrichment purification, the primary desorption is performed by providing a first desorption liquid, and in the second to last stages of enrichment purification, the primary desorption is performed by providing a mixture of the first desorption liquid and one of the plurality of second liquid streams obtained in the previous stage of the enrichment purification process.

[0011] Further, in the second to last stages of enrichment purification, the primary desorption is performed by providing a mixture of the first desorption liquid and the first of the plurality of second liquid streams obtained in the previous stage of the enrichment purification process.

[0012] Further, the final target ion is recovered from the first liquid stream obtained in each stage of the enrichment purification process.

[0013] Further, in each stage of the enrichment purification process, the pH of the produced water sample is adjusted to be within a predetermined range prior to the adsorption operation.

[0014] Further, the pH of the produced water sample is adjusted to be not less than 7.5 using bicarbonate slow-release spheres.

[0015] Further, the bicarbonate slow-release spheres are prepared by: adding bicarbonate particles and a pore support material to a melt of a natural organic material, and after cooling, obtaining microspheres; and impregnating the microspheres in a solution of a non-water-soluble cellulose derivative to form a film of the non-water-soluble cellulose derivative on the surface of the microspheres, to obtain the bicarbonate slow-release spheres.

[0016] Further, the final target ion is a monovalent cation, preferably lithium or potassium.

[0017] Further, the original to-be-treated produced water stream is pre-separated before the produced water sample is subjected to multi-stage enrichment purification, wherein a first target ion and a second target ion in the original to-be-treated produced water stream are separated to obtain a first solution containing the first target ion and a second solution containing at least impurity ions, the second target ion and a final target ion.

[0018] Further, the impurity ions in the second solution are removed to obtain a third solution, and the third solution is treated to obtain a first product containing the second target ion and the produced water sample, wherein the third solution is subjected to electrolysis treatment, and electrolytic tail water obtained is used as the produced water sample.

[0019] Further, the first target ion is at least one selected from the group consisting of strontium ions, barium ions and uranium ions, and the second target ion is a halogen ion, preferably at least one selected from the group consisting of bromine ions, chlorine ions and iodine ions.

[0020] According to a second aspect of the present application, there is provided an enrichment purification device for extracting target ions from produced water, comprising a plurality of enrichment purification assemblies connected in sequence, each of the enrichment purification assemblies comprising an enrichment container for filling with an adsorbent, a first desorption container connected to an input end of the enrichment container, and a storage container and a plurality of intermediate containers connected to an output end of the enrichment container, wherein the enrichment container in each of the enrichment purification assemblies is configured to accept a produced water sample containing target ions and perform adsorption treatment on the produced water sample with respect to the target ions by using the adsorbent, and perform one primary desorption on the adsorbent by using a first desorption liquid from the first desorption container, and deliver a first liquid stream obtained to the storage container, and the enrichment container in each of the enrichment purification assemblies is further configured to perform a plurality of secondary desorptions on the adsorbent by using a second desorption liquid, and deliver a plurality of second liquid streams obtained to the plurality of intermediate containers respectively, to be used for primary desorption and secondary desorption of a next enrichment purification assembly.

[0021] Further, the number of secondary desorptions performed in each of the enrichment purification assemblies is less than the number of secondary desorptions performed in a previous enrichment purification assembly, until no secondary desorption is performed in a last enrichment purification assembly.

[0022] Further, the enrichment and purification device comprises n enrichment and purification assemblies connected in sequence, the number of intermediate containers in each enrichment and purification assembly is equal to the number of secondary desorption processes performed in the enrichment and purification assembly, wherein n-(j-1) intermediate containers are arranged in the j-1th enrichment and purification assembly, and the n-(j-1) intermediate containers are connected with the enrichment container of the jth enrichment and purification assembly, wherein n is an integer greater than or equal to 3, and j is an integer from 2 to n.

[0023] Further, in the 2nd and subsequent enrichment and purification assemblies, the primary desorption is performed by mixing the first desorption solution from the first desorption container of the enrichment and purification assembly (30) and one portion of the second solution stream from one of the intermediate containers in the previous enrichment and purification assembly, and each portion of the second solution stream from the remaining intermediate containers in the previous enrichment and purification assembly is used for each secondary desorption process of the enrichment and purification assembly.

[0024] Further, in the 2nd and subsequent enrichment and purification assemblies, the primary desorption is performed by mixing the first desorption solution from the first desorption container of the enrichment and purification assembly and the second solution stream from the first intermediate container in the previous enrichment and purification assembly.

[0025] Further, the input end of the enrichment container of the 1st enrichment and purification assembly is further connected with a second desorption container for providing an initial second desorption solution.

[0026] Further, the input end of the enrichment container of each enrichment and purification assembly is further connected with an adjusting container filled with an adjusting agent for adjusting the pH value of the produced water sample to a predetermined range.

[0027] Further, the target ion is a monovalent cation, preferably lithium or potassium.

[0028] The present application can at least achieve the following beneficial effects. The process and device for extracting associated resources from produced water provided by the present application separate the first target ion and other ions through pre-separation treatment, and remove impurity ions before electrolysis in the electrolysis device. In this way, the formation of impurity ions such as calcium ions and magnesium ions on the electrode during the electrolytic oxidation of the target ion can be avoided, thereby improving the electrolysis efficiency and increasing the effective operation time of the electrolysis device. At the same time, the adverse effects of impurity ions such as calcium ions and magnesium ions on the adsorption and desorption of the third target ion in the enrichment and purification device are also avoided.

[0029] On the one hand, the purification assembly of the electrolysis device can separate the first product from the electrolysis product of the electrolysis assembly, and then make the first product pass through the electrolysis assembly through the heat exchange pipe. In this way, the heat of the first product can be transferred to the electrolysis assembly, thereby improving the efficiency of blowing the electrolysis product out of the electrolysis assembly.

[0030] On the other hand, the enrichment and purification device adsorbs the third target ion from the electrolysis tail water, once primary desorbs, and multiple secondary desorbs, that is, through the first desorption solution, the second target ion adsorbed by the adsorbent is desorbed once, and through the second desorption solution, the third target ion in the internal pore of the adsorbent is migrated down by using the concentration gradient, so that the nearly complete extraction of the third target ion is realized. In this way, the adsorbent is fully utilized, and the extraction rate of the second target ion is effectively improved. And before the adsorbent adsorbs the third target ion, the pH value of the electrolysis tail water is adjusted by the adjusting agent, so as to improve the adsorption effect of the adsorbent. By using the bicarbonate slow-release ball to release bicarbonate in the electrolysis tail water, not only can the pH of the electrolysis tail water be stably maintained above 7.5 in the adsorption process of the second target ion, so that the adsorbent is in a suitable alkaline environment, but also the exchange of lithium hydrogen ions on the surface of the adsorbent is promoted by the reaction of bicarbonate and hydrogen ions, so as to promote the adsorption of the third target ion.

[0031] In addition, the process and device for extracting associated resources from produced water provided by the present application also have high applicability. The process and device can not only extract strontium elements, bromine elements and lithium elements, but also extract uranium elements, rubidium elements, cesium elements, iodine elements and other elements after adjusting the first ion exchange resin, the second ion exchange resin and the adsorbent. BRIEF DESCRIPTION OF DRAWINGS

[0032] The present application will be further described below in combination with the drawings and examples.

[0033] Fig. 1 is a flow chart of a process for extracting associated resources from produced water.

[0034] Fig. 2 is a process flow chart for extracting strontium, bromine and lithium from produced water based on the process shown in Fig. 1.

[0035] Fig. 3 is a structural schematic diagram of an electrolysis device used in the process shown in Fig. 1.

[0036] Fig. 4 is a structural schematic diagram of an electrolysis assembly of the electrolysis device shown in Fig. 3.

[0037] Fig. 5 is a schematic diagram of a manifold structure of an enrichment and purification device used in the process shown in Fig. 1 in one embodiment.

[0038] Fig. 6 is a schematic diagram of a manifold structure of an enrichment and purification device used in the process shown in Fig. 1 in another embodiment.

[0039] In the drawings, the meanings of various reference signs are as follows:

[0040] 100, electrolysis device; 200, enrichment and purification device;

[0041] 10, electrolysis assembly; 11, electrolytic cell; 111, liquid inlet; 112, gas outlet; 113, liquid outlet; 114, spacer; 115, first chamber; 116, second chamber; 12, electrolytic element; 13, nozzle; 14, direct current power supply;

[0042] 20, purification assembly; 21, pipe injector; 22, gas-liquid separator; 23, first fan; 24, first storage tank; 25, distillation column; 251, filler; 252, first input port; 253, second input port; 254, first output port; 255, second output port; 26, heat exchange pipe; 261, first end; 262, second end; 27, second fan; 28, second storage tank;

[0043] 30, enrichment purification assembly; 31, enrichment container; 32, first desorption container; 33, storage container; 34, second desorption container; 35, intermediate container;

[0044] 40, adjustment container. DETAILED DESCRIPTION

[0045] In order to make the technical problems to be solved by the present application, technical solutions and beneficial effects clearer, the present application will be described in detail in conjunction with the drawings. The drawings are simplified schematic diagrams, and only schematically illustrate the basic structure of the present application, and therefore only show the structures related to the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0046] Referring to FIG. 1, the present application provides a process for extracting associated resources from produced water, comprising the following steps.

[0047] In step S1, the produced water is pre-separated to separate the first target ion, the second target ion and the third target ion in the produced water, to obtain a first solution containing the first target ion, and a second solution containing at least the impurity ion, the second target ion and the third target ion.

[0048] It should be understood that the produced water is preferably oilfield produced water.

[0049] The first target ion can be a metal ion such as barium ion, strontium ion, uranium ion, etc., and the impurity ion can be an ion such as calcium ion, magnesium ion, iron ion, etc., which can affect the extraction of the second target ion and the third target ion. The third target ion can be a metal ion such as lithium ion, rubidium ion, cesium ion, etc. In the produced water, the second target ion is generally a non-metal ion such as chloride ion, bromide ion, iodide ion, etc. The first target ion, the second target ion, and the third target ion are the associated resources in the produced water. It is easy to understand that the specific types of the first target ion, the second target ion, and the third target ion need to be determined according to factors such as extraction cost, economic value of the final extraction product, abundance of the corresponding element in the produced water, and difficulty of industrialization, and need to meet the extraction of the process and be able to be processed by the device in the process.

[0050] In some embodiments, before the pre-separation treatment of the produced water, the produced water can be subjected to filtration, oil removal, etc., so as to remove solid impurities such as silt and organic matters such as oil stains in the produced water, thereby avoiding the influence of silt, oil stains, etc. on the pre-separation treatment of the produced water. These treatments are well known to those skilled in the art and will not be described in detail here.

[0051] In some embodiments, in step S1, the produced water can be subjected to the pre-separation treatment by using a first ion exchange resin capable of selectively adsorbing the first target ion, so as to intercept the first target ion from the produced water, and obtain the second solution. Then, the first target ion intercepted by the first ion exchange resin is eluted with water and / or acid liquor to obtain the first solution. It should be understood that the first ion exchange resin has a first target ion affinity functional group so as to intercept the first target ion in the produced water.

[0052] In a specific embodiment and implementation, the first target ion is strontium ion. The first ion exchange resin is ion exchange resin D001 or ion exchange resin DJH003, and the first target ion affinity functional group is a sulfonic acid group.

[0053] In some embodiments and implementations, in order to continuously extract the associated resources of the produced water in stages, after the first solution is collected, the first ion exchange resin is subjected to water washing so as to remove residual acid liquor on the first ion exchange resin. Then, the first ion exchange resin is regenerated by transformation through alkali liquor elution, and finally, the first ion exchange resin is subjected to water washing to remove residual alkali liquor on the first ion exchange resin, so that the first ion exchange resin can continue to selectively adsorb the first target ion. The acid liquor and the alkali liquor are determined according to the specific type of the first ion exchange resin.

[0054] In step S2, impurity ions in the second solution are removed to obtain a third solution.

[0055] In some embodiments, the impurity ions in the second solution can be intercepted by a second ion exchange resin capable of selectively adsorbing the impurity ions, and the third solution is obtained.

[0056] In a specific embodiment and implementation, the impurity ions are calcium ions and / or magnesium ions, and the second ion exchange resin is a calcium-magnesium chelating resin.

[0057] Similarly, after the selective adsorption of the second ion exchange resin on the impurity ions reaches the adsorption endpoint, the second ion exchange resin can be water-washed, acid-washed, and alkali-washed to achieve the transformation of the second ion exchange resin, and finally water-washed to remove residual alkali solution on the second ion exchange resin, thereby regenerating the second ion exchange resin and enabling the second ion exchange resin to continue to selectively adsorb the impurity ions.

[0058] In step S3, the third solution is electrolyzed by the electrolysis device 100 to obtain a first product and electrolysis tail water.

[0059] During operation, the electrolysis device 100 often produces thick scale. This not only affects the electrolysis of the third solution by the electrolysis device 100, but also frequently stops production to remove these thick scales. In the present application, by removing impurity ions such as calcium ions and magnesium ions in step S2, the generation of a large amount of scale in the electrolysis device 100 can be effectively avoided, thereby improving the electrolysis efficiency of the electrolysis device 100 and prolonging the effective operation time of the electrolysis device 100. The specific structure of the electrolysis device 100 will be described in detail below.

[0060] In some specific embodiments and implementations, the first product can be chlorine element and / or compound, bromine element and / or compound, and iodine element and / or compound.

[0061] In step S4, the third target ions in the electrolysis tail water are adsorbed and desorbed by the enrichment and purification device 200 to obtain a fourth solution with a concentration of the third target ions not less than a predetermined value.

[0062] In some embodiments, several adsorbents arranged in the enrichment and purification device 200 are capable of selectively adsorbing the third target ions. The specific structure of the enrichment and purification device 200, as well as the process of adsorption and desorption, will be described in detail below.

[0063] In some embodiments, the third target ion is lithium ion and the predetermined value is 0.2 g / L. It is easily understood that the predetermined value can be selected by those skilled in the art according to actual conditions.

[0064] In step S5, the first target ion and the third target ion are recovered from the first solution and the fourth solution respectively to obtain a second product and a third product.

[0065] In some embodiments, the first solution and the fourth solution can be treated by concentration, evaporation, precipitation, washing, drying, etc. to obtain the second product and the third product. In the process of steps S1 to S4, not only the separation of the first target ion, the second target ion and the third target ion is achieved, but also the third target ion is enriched by the enrichment and purification device 200, which increases the concentration of the third target ion in the fourth solution and facilitates the subsequent concentration, evaporation and precipitation, etc. to reduce the energy consumption required to obtain the third product.

[0066] In some embodiments, the concentration of lithium ion as the third target ion in the produced water is generally in the range of 10 mg / L to 100 mg / L. After the treatment of the enrichment and purification device 200 in step S4, the concentration of lithium ion in the fourth solution can reach at least 0.2 g / L.

[0067] It is to be noted that the implementation order of steps S1 to S5 can be adjusted according to actual conditions in the context of the present application, i.e. the process of the present application can not be implemented in the order of steps S1 to S5.

[0068] In addition, for the sake of convenience, the present application is introduced in the above by taking the process including steps S1 to S5 as an example. However, it is easily understood by those skilled in the art that the process according to the present application does not necessarily include all the above steps S1 to S5. On the contrary, according to actual conditions, those skilled in the art can only implement one or a combination of multiple arbitrary steps of the above steps S1 to S5 in order to extract one or more specific target ions in the produced water.

[0069] Example 1

[0070] In combination with FIG. 1 and FIG. 2, the above process will be described in detail. In the oilfield produced water to be treated, the concentration of chloride ions is not less than 2 g / L, the concentration of lithium ions is 65 mg / L, the concentration of bromide ions is 230 mg / L, the concentration of bicarbonate ions is 150 mg / L, the concentration of strontium ions is 40 mg / L, the concentration of oil is 2500 mg / L, the concentration of suspended solids is 110 mg / L, the concentration of calcium ions is 730 mg / L, and the concentration of magnesium ions is 55 mg / L.

[0071] In step S101, after removing the impurities such as silt, suspended solids, and oil in the oilfield produced water, the oilfield produced water is subjected to pre-separation treatment. First, the strontium ions in the produced water are selectively adsorbed by ion exchange resin D001. Then, the ion exchange resin D001 is eluted by water washing, acid washing, or the like, so as to elute the strontium ions adsorbed by the ion exchange resin D001, thereby obtaining a first solution containing strontium ions. Since the lithium ions, bromide ions, and other ions in the produced water are hardly adsorbed by the ion exchange resin D001, the second solution can be directly obtained after the strontium ions are adsorbed. The ion exchange resin D001 is purchased from Xi'an Lanxiao Technology Co., Ltd.

[0072] Specifically, the ion exchange resin D001 can be eluted multiple times by water and / or 1.6 wt% sulfuric acid solution, so as to sufficiently elute the strontium ions adsorbed by the ion exchange resin D001. The first solution is measured, wherein the concentration of strontium ions is 800 mg / L, the concentration of calcium ions is 55 mg / L, the concentration of magnesium ions is 6 mg / L, the concentration of lithium ions is 5 mg / L, and the concentration of bicarbonate ions is 150 mg / L.

[0073] Since the properties of strontium ions in adsorption are extremely similar to those of calcium ions and magnesium ions as impurity ions, the calcium ions and magnesium ions can only be removed after the strontium ions are extracted, otherwise part of the strontium ions will be removed when the calcium ions and magnesium ions are removed.

[0074] In step S201, the calcium ions and magnesium ions in the second solution are selectively adsorbed by a calcium-magnesium chelating resin. After the adsorption is completed, a third solution containing at least lithium ions and bromide ions is obtained. The third solution is measured, wherein the concentration of lithium ions is 52 mg / L, the concentration of strontium ions is 5 mg / L, the concentration of calcium ions is 70 mg / L, the concentration of magnesium ions is 5 mg / L, and the concentration of bicarbonate ions is 150 mg / L. Obviously, after step S201, the concentrations of calcium ions and magnesium ions are significantly reduced.

[0075] In step S301, the third solution is electrolyzed by the electrolysis device 100. During the electrolysis process, the anode of the electrolysis device 100 continuously generates bromine, chlorine, while the cathode continuously generates hydrogen. The bromine generated in the electrolysis device 100 is blown out at a temperature of at least 20°C, and after separation, purification and other treatments, liquid bromine is obtained as the first product. The third solution flows out of the electrolysis device 100 after electrolysis, and the electrolysis tail water is obtained. The electrolysis tail water is measured, and the concentration of lithium ions is 52 mg / L, the concentration of strontium ions is 5 mg / L, the concentration of calcium ions is 70 mg / L, the concentration of magnesium ions is 5 mg / L, and the concentration of bicarbonate is 140 mg / L.

[0076] In step S401, the lithium ions in the electrolysis tail water are adsorbed and fractionally desorbed by the enrichment purification device 200 to obtain a fourth solution. The fourth solution is measured, and the concentration of lithium ions is 1.0 g / L, the concentration of calcium ions is 20 mg / L, the concentration of magnesium ions is 1 mg / L, the concentration of strontium ions is 1 mg / L, and the concentration of bicarbonate is 1 mg / L.

[0077] In step S501, after the first solution and the fourth solution are concentrated and evaporated respectively, a corresponding precipitant is added to precipitate strontium ions and lithium ions, so as to obtain strontium carbonate as the second product and lithium carbonate as the third product.

[0078] Specifically, after the pH of the first solution is adjusted to 5-7, concentration and evaporation are performed, then strontium hydroxide is added, reacted under stirring, and magnesium hydroxide and calcium carbonate precipitates are generated. Then filtration is performed to obtain a strontium ion mother liquor. It is measured that the content of strontium ions in the mother liquor is 2.2 g / L. Then an excess of ammonium bicarbonate is added to the strontium ion mother liquor, and a double decomposition reaction occurs at room temperature to generate strontium carbonate precipitate. After filtration, the filter residue is collected, and after washing and drying, strontium carbonate is obtained. It is measured that the purity of strontium carbonate is 99%.

[0079] After the pH of the fourth solution is adjusted to 5-7, concentration and evaporation are performed, then sodium hydroxide and an appropriate amount of sodium carbonate are sequentially added to precipitate magnesium ions and calcium ions in the fourth solution. Then sodium carbonate is added to the filtrate after filtration to obtain lithium carbonate precipitate. It is measured that the content of calcium and magnesium elements in the lithium carbonate precipitate is 0, and the content of sodium element is 2.8 wt%. Finally, the lithium carbonate precipitate is washed with hot water at a temperature higher than 90°C, then centrifuged, and the lower precipitate is collected, dried and obtained as industrial-grade lithium carbonate. It is measured that the purity of lithium carbonate is more than 99.2%.

[0080] Example Two

[0081] The difference between Example Two and Example One is that the enrichment and purification device 200 is cycled for multiple times of desorption after adsorption of lithium ions is completed.

[0082] Comparative Example One

[0083] The difference between Comparative Example One and Example One is that no selective adsorption of impurity ions is performed by the second ion exchange resin, and the extraction sequence of strontium ions, bromide ions and lithium ions is different. Since the property of strontium ions in adsorption is very similar to that of calcium ions and magnesium ions as impurity ions, calcium ions and magnesium ions can only be removed after strontium ions are extracted, otherwise part of strontium ions will be removed when calcium ions and magnesium ions are removed.

[0084] In Comparative Example One, lithium ions in produced water are first adsorbed and fractionally desorbed by the enrichment and purification device 200 to obtain a fourth solution; then strontium ions are selectively adsorbed by the first ion exchange resin to obtain a first solution; finally, electrolysis is performed by the electrolysis device 100 to obtain liquid bromine.

[0085] Comparative Example Two

[0086] The difference between Comparative Example Two and Example One is that no selective adsorption of impurity ions is performed by the second ion exchange resin, and the extraction sequence of strontium ions, bromide ions and lithium ions is different.

[0087] In Comparative Example Two, produced water is first electrolyzed by the electrolysis device 100 to obtain liquid bromine; then lithium ions in produced water are adsorbed and fractionally desorbed by the enrichment and purification device 200 to obtain a fourth solution; finally, strontium ions are selectively adsorbed by the first ion exchange resin to obtain a first solution. Similarly, since the property of strontium ions in adsorption is very similar to that of calcium ions and magnesium ions as impurity ions, calcium ions and magnesium ions can only be removed when strontium ions are extracted.

[0088] The ion concentration information of each solution in the associated resource extraction process of the above-mentioned Example One, Example Two, Comparative Example One and Comparative Example Two is arranged in Table 1.

[0089] Table 1. Ion concentration of each solution in the associated resource extraction process of produced water

[0090] As can be seen from Table 1, in the process of the associated resource gradient extraction of the produced water in Embodiment 1 and Embodiment 2, strontium ions are preliminarily separated out through pre-separation treatment, then calcium ions and magnesium ions are removed, and then electrolysis is performed to separate out bromine and lithium in sequence. According to the above extraction sequence, the strontium ion content in the first solution is as high as 800 mg / L, the calcium ion content is as low as 55 mg / L, and the magnesium ion content is as low as 6 mg / L. The calcium ion and magnesium ion contents in the third solution are very low, and the third solution is used as the water inlet of the electrolysis device 100, which can avoid the formation of a large amount of scale of calcium ions and magnesium ions on the electrode in the electrolysis process, thereby affecting the operation safety and service life of the electrolysis equipment. The calcium ion and magnesium ion contents in the electrolysis tail water are very low, and the electrolysis tail water is used as the water inlet of the enrichment and purification device 200, which avoids the interference of a large amount of calcium ions and magnesium ions on the adsorption and extraction of lithium; the calcium ion content in the fourth solution obtained is as low as 20 mg / L, and the magnesium ion content is as low as 1 mg / L.

[0091] Next, the electrolysis device 100 of the present application will be described. As shown in FIGS. 3 and 5, the electrolysis device 100 comprises an electrolysis assembly 10 and a purification assembly 20 connected to the electrolysis assembly 10. After the electrolysis assembly 10 electrolyzes the third solution, the first gas generated is introduced into the purification assembly 20, and then the first gas is subjected to separation, purification and other treatments in the purification assembly 20, thereby obtaining the first product. The electrolysis tail water flows out of the electrolysis device 100, and then is transported to the enrichment and purification device 200, so as to adsorb and fractionally desorb the third target ions in the electrolysis tail water, thereby obtaining the fourth solution.

[0092] In combination with FIGS. 3 and 4, in some embodiments, the electrolysis assembly 10 comprises an electrolysis tank 11, a plurality of electrolysis pieces 12 arranged in the electrolysis tank 11, and a plurality of nozzles 13 arranged in the electrolysis tank 11 and in parallel communication with each other. The bottom of the electrolysis tank 11 is provided with a liquid inlet 111 for injecting the third solution into the electrolysis tank 11. The top of the electrolysis tank 11 is provided with a gas outlet 112 in communication with the purification assembly 20, and a liquid outlet 113 located below the gas outlet 112. The inside of the electrolysis tank 11 is provided with a partition 114 for dividing the internal space of the electrolysis tank 11 into a first chamber 115 located at the lower part of the electrolysis tank 11 and a second chamber 116 located at the upper part of the electrolysis tank 11. The plurality of electrolysis pieces 12 are installed in the first chamber 115, and the plurality of nozzles 13 are installed in the second chamber 116. The partition 114 can be a partition plate provided with a plurality of holes for fluid communication between the first chamber 115 and the second chamber 116.

[0093] Referring to FIG. 4, the third solution flows into the first chamber 115 from the liquid inlet 111, and the electrolytic members 12 electrolyze the third solution under the electric driving of the direct current power source 14 to oxidize the second target ions in the third solution. The electrolytic tail water obtained after electrolyzing the third solution flows into the second chamber 116 through the partition member 114. The nozzles 13 are immersed in the electrolytic tail water to spray gas into the electrolytic tail water. In this way, the flow state of the electrolytic tail water in the electrolytic cell 11 can be changed, and the volatile product in the electrolytic tail water can be blown out. Finally, the first gas in the electrolytic cell 11 enters the purification assembly 20 from the gas outlet 112, and the electrolytic tail water is discharged from the liquid outlet 113 and then transported to the enrichment purification device 200.

[0094] It is easy to understand that the electrolytic members 12 electrically connected to the positive electrode of the direct current power source 14 are anodes, and the electrolytic members 12 electrically connected to the negative electrode of the direct current power source 14 are cathodes. The anode electrolytic members 12 can be titanium-based electrodes of ruthenium or iridium series, and the cathode electrolytic members 12 can be electrodes of copper, iron, aluminum, or graphite. Each electrolytic member 12 can be in a plate or column structure. In addition, due to the heat effect of the current, the temperature in the electrolytic cell 11 will rise during electrolysis, so that the volatile product in the electrolytic tail water is more easily blown out. Preferably, the outside of the electrolytic cell 11 can be provided with a heat preservation layer to maintain the temperature inside the electrolytic cell 11. The heat preservation layer can be made of heat preservation cotton, rock wool, polyurethane foam board, etc.

[0095] Referring again to FIG. 3, the purification assembly 20 includes a pipeline ejector 21 connected to the gas outlet 112, a gas-liquid separator 22 connected to the pipeline ejector 21, a first fan 23 connected to the gas outlet end of the gas-liquid separator 22, and a first storage tank 24 connected to the liquid outlet end of the gas-liquid separator 22. The pipeline ejector 21 can add an absorbent to the first gas in the process of transporting the first gas in the electrolytic cell 11 to the gas-liquid separator 22, so as to absorb part of the components in the first gas, thereby obtaining a second gas that cannot be absorbed and an absorption product. The gas outlet end of the gas-liquid separator 22 is connected to the first fan 23 by a pipeline, and the first fan 23 is connected to the nozzles 13 by a pipeline to transport the separated second gas to the nozzles 13. The liquid outlet end of the gas-liquid separator 22 is connected to the first storage tank 24 by a pipeline to store the absorption product.

[0096] In some embodiments, the first tank 24 is also connected to a distillation column 25 through a pipe. The inside of the distillation column 25 is provided with a packing 251 for adsorbing the absorption product. The distillation column 25 is provided with a first input port 252 above the packing 251 and a second input port 253 below the packing 251. The distillation column 25 is also provided with a first output port 254 at the top end and a second output port 255 at the bottom end. The first input port 252 is connected to the first tank 24 so that the absorption product in the first tank 24 can be directly adsorbed by the packing 251 after entering the distillation column 25. The second input port 253 is used to deliver a third gas into the distillation column 25 for separating some components in the absorption product by chemical and / or physical actions so as to obtain a first product.

[0097] During the flowing of the absorption product along the surface of the packing 251, the third gas can be in full contact with the absorption product so as to improve the separation effect of the components in the absorption product. The first output port 254 is used to discharge the gaseous product after separation, and the second output port 255 is used to discharge the liquid product after separation. It is easy to understand that the first product can be the gaseous product or the liquid product separated from the absorption product.

[0098] The first tank 24 can play a buffering role between the electrolysis assembly 10 and the distillation column 25. Once the electrolysis rate of the electrolysis assembly 10 on the third solution is greater than the separation rate of the distillation column 25 on the absorption product, the first tank 24 can temporarily store the excessive absorption product so that the absorption product can enter the distillation column 25 at a constant flow rate, ensuring that the distillation column 25 can fully separate the absorption product entering the distillation column 25. Once the electrolysis rate of the electrolysis assembly 10 on the third solution is less than the separation rate of the distillation column 25 on the absorption product, the temporarily stored absorption product in the first tank 24 can still enter the distillation column 25 at a constant flow rate. In this way, the third gas in the distillation column 25 can be fully consumed, thereby avoiding that some components of the third gas are mixed into the gaseous product as impurities, and further ensuring the extraction purity.

[0099] In some embodiments, the first outlet 254 is also connected to a heat exchange pipe 26 arranged in the second chamber 116, as shown in FIG. 3 and FIG. 4. The first end 261 of the heat exchange pipe 26 is connected to the first outlet 254 by a pipe, and the second end 262 of the heat exchange pipe 26 is connected to the second storage tank 28 by a pipe. The third gas and / or gaseous product can conduct heat to the electrolysis tail water in the second chamber 116 through the heat exchange pipe 26 after flowing into the heat exchange pipe 26. In this way, the temperature in the second chamber 116 can be further increased, so that the volatile product after electrolysis is more easily blown out from the electrolysis tail water, thereby achieving step-by-step utilization of energy, improving the utilization rate of energy, and thus reducing the extraction cost and improving the economic benefit. Some third gas and / or gaseous product with a lower boiling point will gradually condense and liquefy after flowing into the heat exchange pipe 26, and finally flow into the second storage tank 20. Preferably, the heat exchange pipe 26 is arranged in the second chamber 116 in a curved and layered manner, so as to increase the contact area between the electrolysis tail water and the heat exchange pipe 26, thereby improving the heat transfer efficiency. More preferably, the heat exchange pipe 26 is made of copper, stainless steel or other metal or alloy, so as to improve the heat transfer efficiency.

[0100] In some embodiments not shown, the second outlet 255 can also be connected to a heat exchange pipe 26 arranged in the second chamber 116. The liquid product can conduct heat to the electrolysis tail water in the second chamber 116 through the heat exchange pipe 26 after flowing into the heat exchange pipe 26.

[0101] In some preferred embodiments, a second fan 27 is further arranged between the first outlet 254 and the first end 261, for increasing the flow rate of the third gas and / or gaseous product flowing into the heat exchange pipe 26. Moreover, the second fan 27 can also increase the flow rate of the third gas in the distillation column 25, thereby improving the reaction rate in the distillation column 25.

[0102] The electrolysis device 100 will be described in detail below with reference to FIG. 3 and FIG. 4 and in combination with the above-mentioned embodiment one. In the third solution entering the first chamber 115 from the liquid inlet 111, the concentration of chloride ions is not less than 2 g / L, the concentration of bromide ions is 230 mg / L, the concentration of lithium ions is 52 mg / L, the concentration of strontium ions is 5 mg / L, the concentration of calcium ions is 70 mg / L, the concentration of magnesium ions is 5 mg / L, and the concentration of bicarbonate is 150 mg / L.

[0103] In the first chamber 115, the voltage between the anode electrolyte 12 and the cathode electrolyte 12 is in the range of 5V to 6V under the electric driving of the direct current power supply 14. The anode electrolyte 12 oxidizes the bromine ions into bromine and the chlorine ions into chlorine. The chlorine produced further oxidizes the bromine ions in the third solution into bromine. The cathode electrolyte 12 reduces the hydrogen ions in the third solution into hydrogen gas. During the electrolysis, the temperature of the third solution is increased by 10°C to 15°C due to the heat effect of the current. The bromine, chlorine and hydrogen gas produced in the electrolysis enter the second chamber 116 through the spacer 114 along with the electrolysis tail water.

[0104] The nozzles 13 continuously spray gas into the electrolysis tail water in the second chamber 116 to blow out the bromine in the electrolysis tail water. Therefore, the first gas entering the pipe injector 21 from the outlet 112 of the electrolytic cell 11 includes at least bromine, chlorine and hydrogen. The pipe injector 21 adds the aqueous solution of sulfur dioxide as an absorbent to the first gas during the delivery of the first gas to the gas-liquid separator 22 to absorb the bromine and chlorine in the first gas and obtain a second gas. Since the hydrogen gas cannot be absorbed by the aqueous solution of sulfur dioxide, the second gas is hydrogen. The first fan 23 re-delivers the hydrogen gas to the nozzles 13 through a pipe to continuously blow out the bromine in the electrolysis tail water.

[0105] It can be understood that an exhaust port and a pressure gauge (not shown in the figure) can also be provided on the pipe between the gas-liquid separator 22 and the first fan 23 or on the pipe between the first fan 23 and the nozzles 13. Once the pressure of the hydrogen gas in the electrolytic cell 11, the pipe injector 21 and the gas-liquid separator 22 exceeds a pre-set safety range, the hydrogen gas can be discharged and collected through the exhaust port to ensure the safety of the entire electrolysis device 100.

[0106] Since the bromine and chlorine can chemically react with the aqueous solution of sulfur dioxide, the absorption product is a mixed solution of sulfuric acid, hydrogen bromide and hydrogen chloride. After entering the first storage tank 24, the absorption product enters the distillation column 25 through the first input port 252 and is then absorbed by the packing 251. The mixed gas of chlorine and water vapor is delivered into the distillation column 25 through the second input port 253 as a third gas. During the flow of the absorption product along the surface of the packing 251, the chlorine and the hydrogen bromide in the absorption product undergo a redox reaction to obtain bromine. The water vapor continuously releases heat so that the temperature in the distillation column 25 is always greater than the boiling point of bromine, allowing the bromine to leave the distillation column 25 in the form of gas through the first output port 254. Therefore, the gaseous product separated from the absorption product is bromine, and the liquid product separated from the absorption product is a hydrogen chloride solution.

[0107] The bromine gas and water vapor flowing out of the first output port 254 flow into the heat exchange tube 26 from the first end 261, and then are condensed and liquefied in the heat exchange tube 26 to obtain liquid bromine and water, which finally flow into the second storage tank 28. In this process, the heat exchange tube 26 conducts the heat of the bromine gas and water vapor to the electrolysis tail water in the second chamber 116, so that the temperature of the electrolysis tail water can continue to increase by 10-15°C, thereby further improving the blowing efficiency of bromine element. In a specific embodiment, the flow rate of the bromine gas and water vapor in the heat exchange tube 26 is in the range of 20-60 m / s, the diameter of the heat exchange tube 26 is in the range of 5-15 cm, and the flow rate of the third solution flowing in the electrolytic cell 11 in the vertical upward direction when the cross-sectional area is 0.8-2 m 2 ~2m 2

[0108] The electrolysis tail water discharged from the liquid outlet 113 of the electrolytic cell 11 is transported to the enrichment and purification device 200 to obtain the fourth solution with the concentration of the third target ion not less than a predetermined value.

[0109] The enrichment and purification device 200 of the present application will be described below. Referring to FIGS. 5 and 6, the enrichment and purification device 200 includes n enrichment and purification assemblies 30 connected in series or in parallel, where n is an integer greater than or equal to 3. Each enrichment and purification assembly 30 includes an enrichment container 31 filled with an adsorbent, a first desorption container 32 connected to the input end of the enrichment container 31, and a storage container 33 connected to the output end of the enrichment container 31. The adsorbent in the enrichment container 31 can selectively adsorb the third target ion in the electrolysis tail water transported to the enrichment container 31, so as to achieve the purpose of enriching the third target ion. The first desorption container 32 is used to store a first desorption solution, so as to transport the first desorption solution to the enrichment container 31 after the adsorbent adsorbs the third target ion, thereby desorbing the third target ion adsorbed by the adsorbent in the first stage, and further obtaining the fourth solution flowing into the storage container 33. It can be understood that after the fourth solutions in the storage containers 33 of the n enrichment and purification assemblies 30 are combined, preliminary concentration, evaporation, etc. can be performed to ensure that the concentration of the third target ion is not less than a predetermined value.

[0110] ​The skilled in the art can select the corresponding adsorbent according to the specific type of the third target ion to be extracted. Similarly, the specific type of the first eluent can be determined according to the selected adsorbent and the third target ion, etc. For example, when the third target ion is lithium ion, the adsorbent can be selected from titanium-based adsorbent or aluminum-based adsorbent, and the first eluent can be selected from dilute hydrochloric acid, dilute sulfuric acid, or other acidic solution.

[0111] In some preferred embodiments, for the first enrichment and purification assembly 30, the input end of the enrichment container 31 is further connected with a second elution container 34 for storing a second eluent, and the output end of the enrichment container 31 is further connected with n-1 intermediate containers 35. For the first enrichment and purification assembly 30, after the first eluent in the first elution container 32 elutes the third target ion adsorbed by the adsorbent in the enrichment container 31, the second eluent in the second elution container 34 is input into the enrichment container 31 to perform n-1 secondary elutions on the adsorbent in the enrichment container 31, so as to sufficiently elute the third target ion. The intermediate solutions obtained after each secondary elution are respectively stored in the n-1 intermediate containers 35.

[0112] For the i-th enrichment and purification assembly 30, the input end of the enrichment container 31 is further connected with the n-(i-1) intermediate containers 35 of the (i-1)-th enrichment and purification assembly 30, and the output end of the enrichment container 31 is further connected with n-i intermediate containers 35. Herein, 2≤i<n and i is an integer. The first eluent in the first elution container 32 of the i-th enrichment and purification assembly 30 is combined with the intermediate solution in the first intermediate container 35 of the (i-1)-th enrichment and purification assembly 30, and then the adsorbent in the enrichment container 31 is collectively subjected to one primary elution, thereby obtaining a fourth solution. The fourth solution flows into the storage container 33 of the i-th enrichment and purification assembly 30. Then, the adsorbent in the enrichment container 31 of the i-th enrichment and purification assembly 30 is subjected to n-(i-1)-1 secondary elutions by the intermediate solutions in the second to n-(i-1)-th intermediate containers 35 of the (i-1)-th enrichment and purification assembly 30. The intermediate solutions obtained after each secondary elution are respectively stored in the n-i intermediate containers 35 of the i-th enrichment and purification assembly 30.

[0113] The input end of the enrichment container 31 of the nth enrichment and purification assembly 30 (i.e. the last enrichment and purification assembly 30) is further connected to the first intermediate container 35 of the (n-1)th enrichment and purification assembly 30, and the output end of the enrichment container 31 is further connected to a tail liquid container (not shown in the figure) for storing adsorption tail liquid. The first desorption liquid in the first desorption container 32 of the nth enrichment and purification assembly 30 is combined with the intermediate solution in the first intermediate container 35 of the (n-1)th enrichment and purification assembly 30, and then the adsorbent in the enrichment container 31 is desorbed to obtain a fourth solution. The fourth solution flows into the storage container 33 of the nth enrichment and purification assembly 30.

[0114] It should be understood that, in actual production, the fixed bed type or the continuous ion exchange type can be used to assemble the n enrichment and purification assemblies 30 by fully considering the construction cost, production efficiency and the like.

[0115] In some preferred embodiments, the input end of the enrichment container 31 of at least one enrichment and purification assembly 30 is further connected to an adjusting container 40 for storing an adjusting agent capable of adjusting the pH. More preferably, the input end of the enrichment container 31 of each enrichment and purification assembly 30 is connected to an adjusting container 40.

[0116] As shown in FIG. 5, in some embodiments, the n adjusting containers 40 can be connected in parallel. The electrolysis tail water can be directly injected into the enrichment containers 31 of the enrichment and purification assemblies 30 after being injected into the n adjusting containers 40 at the same time, so as to adjust the pH of the electrolysis tail water to a predetermined range. In this way, the adsorption effect of the adsorbent on the third target ion in the electrolysis tail water can be effectively improved.

[0117] As shown in FIG. 6, in some embodiments, the n adjusting containers 40 can be connected in series between the enrichment and purification assemblies 30. The electrolysis tail water can sequentially pass through the adjusting containers 40 and the enrichment containers 31 of the enrichment and purification assemblies 30. In this way, the third target ion in the electrolysis tail water can be fully adsorbed on the premise of improving the adsorption effect of the adsorbent on the third target ion.

[0118] The enrichment and purification device 200 will be described in detail below in combination with the above-mentioned embodiment one. In the electrolysis tail water entering the enrichment and purification device 200, the concentration of lithium ions is 52 mg / L, the concentration of strontium ions is 5 mg / L, the concentration of calcium ions is 70 mg / L, the concentration of magnesium ions is 5 mg / L, and the concentration of bicarbonate is 140 mg / L.

[0119] The adjusting agent filled in each adjusting container 40 is bicarbonate slow-release agent, so as to adjust the pH value of the electrolytic tail water flowing through each adjusting container 40 to not less than 7.5. After the electrolytic tail water with the pH value not less than 7.5 flows into each enrichment container 31, the adsorbent in each enrichment container 31 selectively adsorbs lithium ions. Specifically, the adsorbent is a titanium-based adsorbent or a manganese-based adsorbent, and the delivery flow rate of the electrolytic tail water is 35 mL / min. After 1 h to 24 h, when the pH value of the adsorption tail liquid flowing out of each enrichment container 31 is less than 4, it can be determined that each enrichment and purification assembly 30 reaches the adsorption end point. At this time, the concentration of lithium ions in the adsorption tail liquid flowing out of each enrichment container 31 is not higher than 4 mg / L, and the calculation can obtain that the adsorption recovery rate of lithium is about 92%. It is easy to understand that each enrichment container 31 can be connected to the reinjection device of the oil and gas well head through the tail liquid container, so as to reinject the adsorption tail liquid into the oil and gas well, thereby meeting the reinjection requirement of produced water.

[0120] After each enrichment and purification assembly 30 reaches the adsorption end point, the adsorbent in each enrichment and purification assembly 30 is subjected to one primary desorption and multiple secondary desorptions in sequence, so as to obtain a fourth solution.

[0121] For the first enrichment and purification assembly 30, the dilute hydrochloric acid in the first desorption container 32 as the first desorption liquid is delivered to the enrichment container 31 at a flow rate of 70 mL / min, so as to perform one primary desorption on the lithium ions adsorbed by the adsorbent, and obtain a fourth solution containing lithium ions. The pH value of the dilute hydrochloric acid is in the range of 1.5-2.0, and the desorption time is 4 h. Then, the water in the second desorption container 34 as the second desorption liquid is delivered to the enrichment container 31 at a flow rate of 140 mL / min, so as to perform n-1 secondary desorptions on the adsorbent. It should be noted that in this embodiment, the primary desorption refers to the displacement of lithium ions in the adsorbent by hydrogen ions in the acid liquid, and the secondary desorption refers to the sufficient desorption of residual lithium ions in the internal pores of the adsorbent by means of the concentration gradient. The intermediate solutions containing lithium ions obtained after each secondary desorption are stored in n-1 intermediate containers 35, respectively.

[0122] For the i-th enrichment and purification assembly 30, the dilute hydrochloric acid in the first desorption container 32 is combined with the intermediate solution in the first intermediate container 35 of the (i-1)-th enrichment and purification assembly 30, and then delivered to the enrichment container 31 at a flow rate of 70 mL / min, so as to desorb the lithium ions adsorbed by the adsorbent therein and obtain a fourth solution containing lithium ions. The desorption time is also 4 h. It is easy to understand that the pH value of the combination of the dilute hydrochloric acid in the first desorption container 32 of the i-th enrichment and purification assembly 30 and the intermediate solution in the first intermediate container 35 of the (i-1)-th enrichment and purification assembly 30 should also be in the range of 1.5-2.0.

[0123] Then, the intermediate solution in the second to the n-(i-1)-th intermediate containers 35 of the i-1-th enrichment and purification assembly 30 is used to perform n-(i-1)-1 times of secondary desorption on the adsorbent in the enrichment container 31 of the i-th enrichment and purification assembly 30 at a flow rate of 140 mL / min. The intermediate solution obtained after each time of secondary desorption is stored in an n-i-th intermediate container 35.

[0124] For the n-th enrichment and purification assembly 30, the first desorption solution in the first desorption container 32 is combined with the intermediate solution in the first intermediate container 35 of the n-1-th enrichment and purification assembly 30, and then the combined solution is used to perform one time of primary desorption on the adsorbent in the enrichment container 31 at a flow rate of 70 mL / min, thereby obtaining the fourth solution.

[0125] It is determined that the average concentration of lithium ions in the first desorption solution obtained after the primary desorption of the first to the n-th enrichment and purification assemblies 30 is 1.0 g / L, and the average concentration of lithium ions in the second desorption solution obtained after the secondary desorption of the first to the n-1-th enrichment and purification assemblies 30 is 100 mg / L. Thus, the average desorption recovery rate of lithium corresponding to the lithium ions contained in the fourth solution is 95%.

[0126] Finally, after the fourth solutions in the storage containers 33 of the n enrichment and purification assemblies 30 are combined, subsequent processing is performed.

[0127] In the above process of adsorbing lithium ions, lithium ions in the electrolytic tail water exchange with hydrogen ions in the adsorbent, thereby realizing the adsorption of lithium ions. At the same time, bicarbonate ions released by the bicarbonate slow-release agent into the electrolytic tail water react with the exchanged hydrogen ions, so as to consume the hydrogen ions, thereby improving the adsorption effect of the adsorbent on lithium ions. Moreover, the bicarbonate ions released by the bicarbonate slow-release agent can continuously react with hydrogen ions, promote the lithium-hydrogen ion exchange on the surface of the adsorbent, thereby promoting the adsorption of lithium, and facilitating the maximum utilization of the high lithium adsorption capacity of the titanium-based adsorbent.

[0128] In the above process of desorbing lithium ions, hydrogen ions in the dilute hydrochloric acid exchange the lithium ions adsorbed by the adsorbent, thereby realizing the enrichment and purification of lithium ions and the resetting of the adsorbent for subsequent adsorption of lithium ions. Moreover, with the primary desorption and the secondary desorption of each enrichment and purification assembly 30 in turn, the operation efficiency of the entire enrichment and purification device 200 can be improved under the premise of effectively ensuring the desorption recovery rate of lithium by gradually reducing the number of times of secondary desorption, so that the enrichment and purification device 200 is more suitable for industrialization and commercialization applications.

[0129] In the above-mentioned embodiment two, the specific adsorption step of the adsorption process is the same as that of embodiment one. After the adsorption is completed, the concentration of lithium ions in the adsorption tail liquid flowing out of each enrichment container 31 is not higher than 4 mg / L, and the calculation can obtain that the adsorption recovery rate of lithium is about 92%.

[0130] However, in the above-mentioned embodiment two, when the first desorption of the first enrichment and purification assembly 30 is carried out, the dilute hydrochloric acid in the first desorption container 32 as the first desorption liquid is transported to the enrichment container 31 at a flow rate of 70 mL / min, so as to desorb the lithium ions adsorbed by the adsorbent. Among them, the desorption time is 4 h. Then the obtained first desorption liquid is re-input into the enrichment container 31 of the first enrichment and purification assembly 30 at a flow rate of 70 mL / min, and the desorption is carried out for 4 times, and each desorption time is 4 h. During this period, the dilute hydrochloric acid can be supplemented to the enrichment container 31 through the first desorption container 32 to maintain the pH of the first desorption liquid at 1.5-2.0.

[0131] The second enrichment and purification assembly and the nth enrichment and purification assembly are respectively subjected to cyclic desorption using the first desorption liquid according to the same steps. Finally, the fourth solution with a lithium ion concentration of 200 mg / L is obtained, and the average desorption recovery rate of lithium is 60%.

[0132] The recovery effect of lithium by the enrichment and purification device 200 in the above-mentioned embodiment one and embodiment two is arranged in table 2.

[0133] Table 2. Recovery effect of lithium

[0134] As can be seen from the comparison between embodiment one and embodiment two, compared with the first desorption liquid cyclic desorption process, the present application has obvious advantages in improving the desorption recovery rate of lithium and the concentration of lithium ions in the fourth solution through the process of one-time first desorption and multiple secondary desorption by the enrichment and purification device 200. Through one-time first desorption by the first desorption liquid and multiple secondary desorption by the second desorption liquid, the desorption recovery rate of lithium ions in the subsequent desorption process is reduced due to the concentration inhibition effect, and the efficient recovery of lithium ions is realized, and the recovery cost of lithium ions is reduced.

[0135] In some embodiments, the adjusting agent filled in each adjusting container 40 is bicarbonate slow-release ball. The bicarbonate slow-release ball is a kind of film microspheres. The film material is a non-water-soluble cellulose derivative, and the microsphere material is a mixture of bicarbonate particles, pore support material and natural organic material.

[0136] Preferably, the mass ratio of the bicarbonate particles, the natural organic material and the porous support material in the bicarbonate sustained-release spheres is (1-5):1:1, for example any value or a range of values consisting of any two values in 1:1:1, 2:1:1, 3:1:1, 4:1:1, 5:1:1. More preferably, the mass ratio of the bicarbonate particles, the natural organic material and the porous support material in the bicarbonate sustained-release spheres is (1-3):1:1.

[0137] Preferably, the average particle size of the bicarbonate sustained-release spheres is 0.8-1.5 cm, so as to ensure the contact area of the bicarbonate sustained-release spheres in the adjusting container 40 with the electrolytic tail water.

[0138] Preferably, the particle size of the porous support material is not higher than 0.2 mm.

[0139] Preferably, the non-water-soluble cellulose derivative is ethyl cellulose and / or methyl cellulose.

[0140] Preferably, the porous support material is fine granular activated carbon; the particle size of the fine granular activated carbon is 0.1-0.2 mm.

[0141] Preferably, the natural organic material is selected from any one of paraffin, chitosan and alginate.

[0142] In some embodiments, the method for preparing the bicarbonate sustained-release spheres comprises the following steps:

[0143] heating the natural organic material to melting, adding the bicarbonate particles, the porous support material, mixing uniformly, pouring into a mold, cooling and forming to obtain the microspheres;

[0144] immersing the microspheres in a solution of the non-water-soluble cellulose derivative, taking out and drying, so that the non-water-soluble cellulose derivative forms a film on the surface of the microspheres to obtain the bicarbonate sustained-release spheres.

[0145] The sustained-release performance of the bicarbonate sustained-release spheres is described below.

[0146] (1) 10 g of the bicarbonate sustained-release spheres prepared in Examples 3-7 and Comparative Example 3 were respectively dispersed in 100 mL of water, and the bicarbonate release experiment was carried out by standing at room temperature;

[0147] (2) The content of bicarbonate in the water in which the bicarbonate sustained-release spheres prepared in each example / comparative example were dispersed was respectively determined by ion chromatography every 6 h, and when the detected bicarbonate content was unchanged, the time point was the release duration;

[0148] (3) The bicarbonate content detected at the time point corresponding to the release duration is converted into the amount of substance of bicarbonate, i.e., the bicarbonate release amount (mol) of the 10 g bicarbonate slow-release ball; the initial content of bicarbonate in the 10 g bicarbonate slow-release ball prepared in each example / counterexample is calculated according to the added amount of sodium bicarbonate particles, and is converted into the initial amount of substance of bicarbonate, i.e., the initial amount of bicarbonate (mol) of the 10 g bicarbonate slow-release ball; and the percentage of the bicarbonate release amount of each bicarbonate slow-release ball to the initial amount of bicarbonate is calculated, i.e., the final release rate (%).

[0149] The results are shown in Table 3.

[0150] Table 3. Slow-release performance of bicarbonate slow-release balls

[0151] As can be seen from Table 3, the type of natural organic material affects the duration of sodium bicarbonate release, and the mass percentage of sodium bicarbonate affects the final release rate of bicarbonate. At room temperature, the final release rate of bicarbonate in the bicarbonate slow-release balls prepared in Examples 3 to 7 can reach a high range of 60%-80%, and the release duration is 4 to 5 days, achieving a stable and efficient bicarbonate release effect, which can continuously release bicarbonate to adjust the pH of the solution. Therefore, by using the bicarbonate slow-release ball, the pH of the electrolytic tail water can be maintained above 7.5 during the lithium ion adsorption process, and the continuous reaction of bicarbonate with hydrogen ions can promote the lithium-hydrogen ion exchange on the surface of the adsorbent, thereby promoting the adsorption of lithium. In actual application, the type of natural organic material and the mass percentage of sodium bicarbonate can be adjusted as needed to obtain a suitable release duration and bicarbonate release amount.

[0152] Compared with Example 3, the bicarbonate slow-release ball prepared in Counterexample 3 does not contain activated carbon as a pore supporting material, and the bicarbonate release capacity is poor. Although the duration of bicarbonate release into water reaches 7 days, the final release rate of bicarbonate is only 40%, which reduces the utilization rate of bicarbonate. In actual application, it will affect the buffering effect and increase the amount of bicarbonate slow-release balls, which is not conducive to cost control.

[0153] It should be emphasized that although the above describes the present application by taking oilfield produced water as an example, the technical solution of the present application is obviously also applicable to other types of produced water. In addition, in the process of the present application, each step can be implemented in a different order from that described, as long as there is no conflict. Furthermore, each device used in the process of the present application (such as the electrolysis device 100 and the enrichment and purification device 200) can be used independently for the corresponding treatment of various types of produced water.

[0154] In addition, although strontium ions, bromide ions and lithium ions are described above as the first target ions, the second target ions and the third target ions, it is understood that the present application is equally applicable to other types of first target ions, second target ions and third target ions. Also, the terms "first", "second" and the like in the present application are used to distinguish similar objects, and are not used to describe a particular order or sequence. It is understood that the terms so used are interchangeable under appropriate circumstances and are merely employed as a matter of convenience to name similar objects for the purpose of distinguishing the various embodiments of the present application.

[0155] Although the present application has been described with reference to preferred embodiments, various modifications can be made to the application without departing from the scope thereof. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided that there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A process for extracting a companion resource from produced water, comprising subjecting a produced water sample to a multistage enrichment purification process for a final target ion, wherein in each stage of the enrichment purification process: subjecting the produced water sample to an adsorption operation for the final target ion using an adsorbent, subjecting the adsorbent to a primary desorption to obtain and store a first liquid stream, subjecting the adsorbent to a plurality of secondary desorptions to obtain a plurality of second liquid streams for use in the primary and secondary desorptions of the next stage of the enrichment purification process.

2. The process according to claim 1, characterized in that, the number of secondary desorptions in the next stage of the enrichment purification process is less than the number of secondary desorptions in the previous stage of the enrichment purification process, until no secondary desorption is performed in the last stage of the enrichment purification process.

3. The process of claim 2, wherein, subjecting the produced water sample to n stages of enrichment purification process, wherein n is an integer greater than or equal to 3, and subjecting the adsorbent to n-i secondary desorptions in the i-th stage of the enrichment purification process, wherein i is an integer from 1 to n.

4. The process of claim 3, wherein, in the first stage of the enrichment purification process, the primary desorption is performed by providing a first desorption liquid, and in the second to last stages of the enrichment purification process, the primary desorption is performed by providing a mixture of the first desorption liquid and one of the plurality of second liquid streams obtained in the previous stage of the enrichment purification process.

5. The process of claim 4, wherein, in the second to last stages of the enrichment purification process, the primary desorption is performed by providing a mixture of the first desorption liquid and the first of the plurality of second liquid streams obtained in the previous stage of the enrichment purification process.

6. The process according to any one of claims 1 to 5, characterized in that, the final target ion is recovered from the first liquid stream obtained in each stage of the enrichment purification process.

7. The process according to any one of claims 1 to 6, characterized in that, in each stage of the enrichment purification process, the pH of the produced water sample is adjusted to a predetermined range before the adsorption operation.

8. The process of claim 7, wherein, the pH of the produced water sample is adjusted to not less than 7.5 using bicarbonate slow-release spheres.

9. The process of claim 8, wherein, the bicarbonate slow-release spheres are prepared by: adding bicarbonate particles and a pore support material to a melt of natural organic material to obtain microspheres after cooling; and immersing the microspheres in a solution of a non-water-soluble cellulose derivative to form a film of the non-water-soluble cellulose derivative on the surface of the microspheres to obtain the bicarbonate slow-release spheres. the final target ion is a monovalent cation, preferably lithium or potassium.

10. The process according to any one of claims 1 to 9, characterized in that, a pre-separation process is performed on an original raw produced water stream to be treated before subjecting the produced water sample to the multistage enrichment purification process, wherein a first target ion and a second target ion are separated from the original raw produced water stream to obtain a first solution containing the first target ion, and a second solution containing at least an impurity ion, the second target ion and the final target ion.

11. The process according to any one of claims 1 to 10, characterized in that, the impurity ion is removed from the second solution to obtain a third solution, which is treated to obtain a first product containing the second target ion, and the produced water sample, 12. The process of claim 11, wherein, wherein the third solution is subjected to an electrolysis process to obtain an electrolysis tail water as the produced water sample. the first target ion is selected from at least one of the group consisting of strontium ion, barium ion and uranium ion, and the second target ion is a halogen ion, preferably selected from at least one of the group consisting of bromine ion, chlorine ion and iodine ion.

13. The process of claim 11, wherein, ​ 14. An enrichment purification device for extracting target ions from produced water, comprising a plurality of enrichment purification assemblies (30) connected in series, each of the enrichment purification assemblies (30) comprising an enrichment container (31) for filling with an adsorbent, a first desorption container (32) connected to an input end of the enrichment container (31), and a storage container (33) and a plurality of intermediate containers (35) connected to an output end of the enrichment container (31), wherein, the enrichment container (31) in each of the enrichment purification assemblies (30) is configured to receive a sample of produced water containing target ions and perform an adsorption process on the sample of produced water with the adsorbent for the target ions, and perform at least one primary desorption on the adsorbent with a first desorption liquid from the first desorption container (32), and deliver a resulting first liquid stream to the storage container (32), the enrichment container (31) in each of the enrichment purification assemblies (30) is configured to further perform a plurality of secondary desorptions on the adsorbent with a second desorption liquid, and deliver a plurality of resulting second liquid streams to the plurality of intermediate containers (32) respectively for use as primary desorption and secondary desorption of a next enrichment purification assembly (30).

15. The enrichment purification device of claim 14, wherein, The number of secondary desorptions performed in each enrichment purification assembly (30) is less than the number of secondary desorptions performed in a previous enrichment purification assembly (30), until no secondary desorption is performed in a last enrichment purification assembly.

16. The enrichment purification device of claim 15, wherein, The enrichment purification device comprises n enrichment purification assemblies (30) connected in series, the number of intermediate containers (35) in each enrichment purification assembly (30) is equal to the number of secondary desorptions performed in the enrichment purification assembly (30), wherein the j-1th enrichment purification assembly (30) is provided with n-(j-1) intermediate containers (35), each of the n-(j-1) intermediate containers (35) is connected to the enrichment container (31) of the jth enrichment purification assembly (30), wherein n is an integer greater than or equal to 3, and j is an integer from 2 to n.

17. The enrichment purification device of claim 16, wherein, In the 2nd and subsequent enrichment purification assemblies (30), the primary desorption is performed with a mixture of the first desorption liquid from the first desorption container (32) of the one enrichment purification assembly (30) and one of the second liquid streams from the intermediate containers (35) in the previous enrichment purification assembly (30), and each of the remaining second liquid streams from the intermediate containers (35) in the previous enrichment purification assembly (30) is used for each of the secondary desorptions of the one enrichment purification assembly (30).

18. The enrichment purification device of claim 17, wherein, In the 2nd and subsequent enrichment purification assemblies (30), the primary desorption is performed with a mixture of the first desorption liquid from the first desorption container (32) of the one enrichment purification assembly (30) and the second liquid stream from the first intermediate container (35) in the previous enrichment purification assembly (30).

19. An enrichment purification device according to any one of claims 14 to 18, characterised in that, The input end of the enrichment container (31) of the 1st enrichment purification assembly (30) is further connected with a second desorption container (34) for providing an initial second desorption liquid.

20. An enrichment purification device according to any one of claims 14 to 19, characterized in that, The input end of the enrichment container (31) of each enrichment and purification assembly (30) is also connected with an adjusting container (40) filled with an adjusting agent for adjusting the pH value of the produced water sample to a predetermined range.

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