System and method for obtaining concentrated lithium from gas field produced water

Abstract

The invention belongs to the field of gas field produced water treatment, and particularly relates to a system and method for obtaining concentrated lithium from gas field produced water. The system for obtaining the concentrated lithium from the gas field produced water comprises an oxidation mechanism, a liquid film mechanism and a concentration mechanism which are connected in sequence, the oxidation mechanism is used for carrying out oxidative degradation on the produced water; the liquid membrane mechanism is used for performing lithium selective extraction on the produced water after oxidative degradation; and the concentration mechanism is used for performing lithium concentration on the produced water after selective extraction. The system provided by the invention can realize effective extraction and concentration of lithium in produced water, and improves the recovery rate of lithium in produced water.

Description

Technical Field

[0001] The invention belongs to the field of gas field produced water treatment, and in particular relates to a system and method for obtaining concentrated lithium from gas field produced water. Background Art

[0002] As my country's strategic goal of "stabilizing oil and increasing gas" continues to advance, crude oil production is rising steadily, and natural gas production is accelerating. The amount of produced water from oil and gas fields during the development of oil and gas fields will also increase significantly. At present, the total amount of produced water from oil and gas fields is nearly 1 billion tons / year, and it is expected to increase by 10% in 2030. Gas field produced water is produced by underground natural gas, with high mineralization and rich in a large number of high value-added components, including lithium, potassium, bromine, iodine, boron, etc. The occurrence grade in some areas can reach the deep salt mineral indicators, with high extraction and utilization value. With the increase in the amount of produced water from gas fields, the overall resource potential is great.

[0003] At present, the main treatment route for gas field produced water is reinjection, and a small amount is discharged in some areas. The surface treatment technology and process of produced water corresponding to reinjection treatment mainly removes suspended solids in the water, using flotation, filtration and other technical methods. The surface treatment of produced water corresponding to discharge treatment includes the removal of sulfides, organic matter, salts, etc., mainly using filtration, flotation, oxidation, membrane separation and other technical methods. At present, in the treatment process of gas field effluent, high value-added components such as lithium in the water cannot be effectively extracted and recycled.

[0004] Lithium is the lightest metal element in nature. It mainly exists in the form of hard rocks such as spodumene, lepidolite and apatite, and also exists in salt lake brine and deep underground brine. Lithium is widely used in important fields such as batteries, glass, and grease. With the development and application of new energy vehicles and energy storage technologies, lithium has attracted much attention in the field of new energy materials and has become an important strategic resource. Driven by the high-quality development of my country's new energy industry, the consumption of lithium will grow rapidly.

[0005] Therefore, it is necessary to extract the lithium from the produced water.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] In order to achieve effective extraction of lithium from gas field produced water, the present invention provides a system and method for obtaining concentrated lithium from gas field produced water. The system of the present invention can achieve effective extraction and concentration of lithium from produced water, thereby improving the recovery rate of lithium from produced water.

[0008] The present invention includes the following technical solutions:

[0009] A first aspect of the present invention provides a system for obtaining concentrated lithium from gas field produced water, comprising an oxidation mechanism, a liquid membrane mechanism and a concentration mechanism connected in sequence;

[0010] The oxidation mechanism is used to oxidize and degrade the produced water;

[0011] The liquid membrane mechanism is used to selectively extract lithium from produced water after oxidation degradation;

[0012] The concentration mechanism is used to concentrate lithium in the produced water after selective extraction.

[0013] Furthermore, the oxidation mechanism includes an oxidation reaction tank.

[0014] Furthermore, the liquid membrane mechanism comprises a stirring and separating tank and a demulsification tank, the oxidation mechanism is connected to the stirring and separating tank, and the stirring and separating tank is connected to the demulsification tank.

[0015] Furthermore, the liquid film mechanism also includes a liquid film preparation device, and the liquid film preparation device is connected to the stirring separation tank.

[0016] Furthermore, the concentration mechanism includes a membrane distillation reactor, a condensation collection tank and a concentrated lithium liquid storage tank; the demulsification tank is connected to the membrane distillation reactor, and the membrane distillation reactor is respectively connected to the condensation collection tank and the concentrated lithium liquid storage tank; preferably, the upper end of the demulsification tank is connected to the emulsion liquid membrane preparation device, and the lower end of the demulsification tank is connected to the membrane distillation reactor.

[0017] A second aspect of the present invention provides a method for obtaining concentrated lithium from gas field produced water, comprising the following steps:

[0018] Oxidative degradation of produced water;

[0019] Selective extraction of lithium from produced water after oxidative degradation;

[0020] The produced water after selective extraction is concentrated for lithium.

[0021] Furthermore, ozone is added to oxidatively degrade the produced water.

[0022] Furthermore, a liquid membrane is added to perform lithium selective extraction treatment on the produced water after oxidative degradation; preferably, the volume ratio of the produced water after oxidative degradation to the volume of the liquid membrane is 0.1-5.

[0023] Furthermore, the preparation method of the liquid film is:

[0024] Mixing ethyl acetate, surfactant, sodium tetraphenylborate, trioctyl phosphate and sodium carbonate solution;

[0025] Stirring at normal temperature and pressure to homogenize and emulsify ethyl acetate, surfactant, sodium tetraphenylborate, trioctyl phosphate and sodium carbonate solution to obtain a liquid film;

[0026] Preferably, the volume ratio of the ethyl acetate to the trioctyl phosphate is 1 to 5, the volume ratio of the trioctyl phosphate to the sodium tetraphenylborate is 1 to 10, the volume ratio of the organic solvent to the sodium carbonate solution is 2 to 20, and the mass fraction ratio of the ethyl acetate to the surfactant is 10 to 100;

[0027] Wherein: the organic solvent comprises ethyl acetate, trioctyl phosphate, sodium tetraphenylborate and a surfactant.

[0028] Furthermore, the HLB value of the surfactant is 3-6.

[0029] By adopting the above technical solution, the present invention has the following advantages:

[0030] 1. The system of the present invention can realize the effective extraction and concentration of lithium in produced water, thereby improving the recovery rate of lithium in produced water.

[0031] 2. The present invention extracts and concentrates lithium from gas field produced water through the process of oxidation pretreatment + liquid membrane selective extraction + membrane distillation concentration, and finally obtains a lithium carbonate solution with a nearly saturated concentration.

[0032] 3. The oxidation mechanism of the present invention can oxidize and degrade organic matter in gas field produced water to reduce the interference of organic matter on subsequent lithium extraction and concentration processes. Selecting ozone to react in the gas-liquid enhancement device can more efficiently and deeply treat organic matter.

[0033] 4. In the preparation of the liquid membrane in the present invention, trioctyl phosphate and tetraphenylammonium borate are used as co-extractants, ethyl acetate is used as a diluent, a sodium carbonate solution is used as an internal phase, and a surfactant is selected with an HLB value in the range of 3 to 6 to prepare an oil-in-water emulsion liquid membrane. The prepared emulsion liquid membrane has a selective extraction effect on lithium ions in gas field produced water, and the liquid membrane extraction method can complete extraction and stripping in one time.

[0034] 5. The liquid membrane demulsification of the present invention adopts a heating demulsification method, and the demulsification temperature is 60-90° C. After heating demulsification, the lower lithium-containing aqueous phase has a certain temperature and can directly enter the membrane distillation reactor for concentration. Since the membrane distillation reactor requires a certain temperature, the present invention can effectively reduce the energy consumption required for heating.

[0035] 6. The fresh water produced by the membrane distillation reactor of the present invention is recycled to the liquid membrane preparation device to supplement softened water, effectively reducing the amount of softened water required. The concentrated water produced by the membrane distillation reactor is the final nearly saturated lithium carbonate solution, providing high-quality raw materials for the production of lithium carbonate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 It is a structural schematic diagram of a system for obtaining concentrated lithium from gas field produced water in an embodiment of the present invention;

[0038] In the attached figure: 10-oxidation mechanism, 11-oxidation reaction tank, 20-liquid membrane mechanism, 21-stirring separation tank, 22-demulsification tank, 23-liquid membrane preparation device, 30-concentration mechanism, 31-membrane distillation reactor, 311-reflux pipe, 312-export pipe, 313-inlet pipe, 314-concentrated lithium outlet pipe ， 32- condensate collection tank, 33- concentrated lithium liquid storage tank, 40- produced water storage tank. DETAILED DESCRIPTION

[0039] The following description provides many different embodiments or examples for implementing different features of the present invention. The components and arrangements described in the following specific examples are only used to simplify the present invention and are only used as examples, not to limit the present invention.

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Example 1

[0042] This embodiment provides a system for obtaining concentrated lithium from gas field produced water, such as Figure 1 As shown, it includes an oxidation mechanism 10, a liquid membrane mechanism 20 and a concentration mechanism 30 connected in sequence;

[0043] The oxidation mechanism 10 is used to oxidize and degrade the produced water;

[0044] The liquid membrane mechanism 20 is used to selectively extract lithium from produced water after oxidation degradation;

[0045] The concentration mechanism 30 is used to concentrate lithium in the produced water after selective extraction.

[0046] Furthermore, the oxidation mechanism 10 comprises an oxidation reaction tank 11. The oxidation reaction tank 11 can be a gas-liquid enhanced reactor such as a supergravity reactor, a venturi reactor, a bubble column reactor, etc.

[0047] Furthermore, the liquid membrane mechanism 20 includes a stirring and separation tank 21 and a demulsification tank 22 , the oxidation mechanism 10 is connected to the stirring and separation tank 21 , and the stirring and separation tank 21 is connected to the demulsification tank 22 .

[0048] Furthermore, the liquid film mechanism 20 also includes a liquid film preparation device 23 , and the liquid film preparation device 23 is connected to the stirring separation tank 21 .

[0049] Furthermore, the concentration mechanism 30 includes a membrane distillation reactor 31, a condensation collection tank 32 and a concentrated lithium liquid storage tank 33; the demulsification tank 22 is connected to the membrane distillation reactor 31, and the membrane distillation reactor 31 is respectively connected to the condensation collection tank 32 and the concentrated lithium liquid storage tank 33; preferably, the upper end of the demulsification tank 22 is connected to the emulsion liquid membrane preparation device 23, and the lower end of the demulsification tank 22 is connected to the membrane distillation reactor 31.

[0050] Furthermore, the membrane distillation reactor 31 can be a plate-and-frame type or a hollow fiber type; the distillation membrane in the membrane distillation reactor 31 is an organic hydrophobic membrane with a pore size of 0.01 to 0.5 μm. The material can be polytetrafluoroethylene, polyvinylidene fluoride, polysulfone or polyethersulfone.

[0051] It should be noted that the reaction tanks, devices and mechanisms in the present invention are all connected by pipelines. In order to improve the transportation efficiency, a pump may be provided in the pipeline.

[0052] Furthermore, a reflux pipe 311 is provided, one end of which is connected to the outlet pipe 312 of the membrane distillation reaction tank, and the other end is connected to the inlet pipe 313 of the membrane distillation reactor 31. The flow ratio between the reflux pipe 311 and the concentrated lithium outlet pipe 314 is 0.1-1.

[0053] Furthermore, the oxidation reaction tank 11 is connected to a produced water storage tank 40 .

[0054] Example 2

[0055] This embodiment provides a method for obtaining concentrated lithium from gas field produced water, comprising the following steps:

[0056] Oxidative degradation of produced water;

[0057] Selective extraction of lithium from produced water after oxidative degradation;

[0058] The produced water after selective extraction is concentrated for lithium.

[0059] Furthermore, ozone is added to oxidize and degrade the produced water. Preferably, the concentration of the ozone is 10-150 mg / L, and the gas-liquid ratio is 0.5-5. Direct oxidation by ozone and indirect oxidation by hydroxyl radicals remove the main organic matter in the water, including organic hydrocarbons, phenols, amines, acids, etc.

[0060] Furthermore, a liquid membrane is added to perform lithium selective extraction treatment on the produced water after oxidative degradation; preferably, the volume ratio of the produced water after oxidative degradation to the volume of the liquid membrane is 0.1-5.

[0061] Furthermore, the preparation method of the liquid film is:

[0062] Mixing ethyl acetate, surfactant, sodium tetraphenylborate, trioctyl phosphate and sodium carbonate solution;

[0063] Ethyl acetate, surfactant, sodium tetraphenylborate, trioctyl phosphate and sodium carbonate solution are homogenized and emulsified by stirring at room temperature and pressure to obtain a liquid membrane; the liquid membrane thus obtained has a selective effect on lithium ions and can allow lithium ions to pass through the liquid membrane in one direction.

[0064] Preferably, the volume ratio of the ethyl acetate to the trioctyl phosphate is 1 to 5, the volume ratio of the trioctyl phosphate to the sodium tetraphenylborate is 1 to 10, the volume ratio of the organic solvent to the sodium carbonate solution is 2 to 20, and the mass fraction ratio of the ethyl acetate to the surfactant is 10 to 100;

[0065] Wherein: the organic solvent comprises ethyl acetate, trioctyl phosphate, sodium tetraphenylborate and a surfactant.

[0066] Preferably, the stirring time in the liquid film preparation is 5 to 120 minutes.

[0067] Furthermore, the HLB value of the surfactant is 3-6.

[0068] Furthermore, when selective lithium extraction is performed on the produced water after oxidative degradation, the liquid membrane is first mixed with the produced water after oxidative degradation and stirred to allow lithium ions in the produced water after oxidative degradation to enter the liquid membrane. The stirring time is 1 to 120 minutes. After stirring, the mixture is allowed to stand for 30 to 180 minutes, and then the liquid membrane and the lower layer of water are separated. The liquid membrane is then demulsified by heating at a temperature of 60 to 90° C. for a demulsification time of 5 to 60 minutes.

[0069] The method of this embodiment can be implemented by the system in Embodiment 1. When the system is used to execute the method of this embodiment, the device therein can also be set, specifically:

[0070] The liquid film preparation device 23 is provided with a stirrer, and the rotation speed of the stirrer is set to 50-1500 rpm.

[0071] Based on Example 1 and Example 2, several examples of obtaining concentrated lithium are listed below:

[0072] Example 1

[0073] The influent in this example is gas field produced water, COD is 215mg / L, initial lithium ion concentration is 39.1mg / L, mineralization is 83g / L, and the volume of gas field produced water to be extracted is 100L. The ozone concentration of the oxidation system is 30mg / L, and the gas-liquid ratio is 3. The total volume of the liquid membrane raw material is 100L, of which trioctyl phosphate is 30v / v%, the volume ratio of trioctyl phosphate to ethyl acetate is 0.2, the volume ratio of trioctyl phosphate to sodium tetraphenylborate is 2, the surfactant is selected as Span 80, the mass is 2wt.%, the concentration of sodium carbonate solution is 0.5mol / L, and the volume of sodium carbonate solution accounts for 15% of the total volume of the raw material. The agitator speed of the liquid membrane preparation device 23 is 600rpm, and the preparation is 15min at normal temperature and pressure. The residence time in the stirring separation tank 21 is 30min, the demulsification temperature is 65℃, and the demulsification time is 35min. The lithium ion concentration in the concentrated water in the concentrated lithium storage tank 33 is 822mg / L, and the concentration multiple is 21 times.

[0074] Example 2

[0075] The influent of the process of the present invention is gas field produced water, COD is 368mg / L, initial lithium ion concentration is 92mg / L, mineralization is 103g / L, and the volume of gas field produced water to be extracted is 50L. The ozone concentration of the oxidation system is 80mg / L, and the gas-liquid ratio is 5. The total volume of the raw material for preparing the emulsified liquid membrane is 250L, wherein trioctyl phosphate is 80v / v%, the volume ratio of trioctyl phosphate to ethyl acetate is 0.8, the volume ratio of trioctyl phosphate to sodium tetraphenylborate is 7, the surfactant is selected as NP-10, the mass is 9wt.%, the concentration of sodium carbonate solution is 4.5mol / L, and the volume of sodium carbonate solution accounts for 40% of the total volume of the raw material. The agitator speed of the liquid membrane preparation device 23 is 1500rpm, and the preparation is 60min at normal temperature and pressure. The residence time in the stirring separation tank 21 is 100min, the demulsification temperature is 95℃, and the demulsification time is 50min. The lithium ion concentration in the concentrated water in the concentrated lithium liquid storage tank 33 is 978 mg / L, and the concentration multiple is 11 times.

[0076] Example 3

[0077] The influent of the process of the present invention is gas field produced water, COD is 152mg / L, initial lithium ion concentration is 51mg / L, mineralization is 68g / L, and the volume of gas field produced water to be extracted is 100L. The ozone concentration of the oxidation system is 50mg / L, and the gas-liquid ratio is 2. The total volume of the raw material for preparing the emulsified liquid membrane is 50L, wherein trioctyl phosphate is 35v / v%, the volume ratio of TOP to ethyl acetate is 0.5, the volume ratio of trioctyl phosphate to sodium tetraphenylborate is 5, the surfactant is KC-23, the mass is 5wt.%, the concentration of sodium carbonate solution is 2mol / L, the volume of sodium carbonate solution accounts for 25% of the total volume of the raw material, the agitator speed of the liquid membrane preparation device 23 is 100rpm, and the preparation is 100min at normal temperature and pressure. The residence time in the stirring separation tank 21 is 180min, the demulsification temperature is 80℃, and the demulsification time is 10min. The lithium ion concentration in the concentrated water in the concentrated lithium storage tank 33 is 876mg / L, and the concentration multiple is 17 times.

[0078] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for obtaining concentrated lithium from gas field produced water, characterized in that: It comprises an oxidation mechanism (10), a liquid membrane mechanism (20) and a concentration mechanism (30) which are connected in sequence; The oxidation mechanism (10) is used to oxidize and degrade the produced water; The liquid membrane mechanism (20) is used to selectively extract lithium from produced water after oxidation degradation; The concentration mechanism (30) is used to concentrate lithium in the produced water after selective extraction.

2. A system for obtaining concentrated lithium from gas field produced water according to claim 1, characterized in that: The oxidation mechanism (10) comprises an oxidation reaction tank (11).

3. A system for obtaining concentrated lithium from gas field produced water according to claim 1 or 2, characterized in that: The liquid membrane mechanism (20) comprises a stirring and separating tank (21) and a demulsification tank (22), the oxidation mechanism (10) is connected to the stirring and separating tank (21), and the stirring and separating tank (21) is connected to the demulsification tank (22).

4. A system for obtaining concentrated lithium from gas field produced water according to claim 3, characterized in that: The liquid film mechanism (20) further comprises a liquid film preparation device (23), and the liquid film preparation device (23) is connected to the stirring separation tank (21).

5. A system for obtaining concentrated lithium from gas field produced water according to claim 3, characterized in that: The concentration mechanism (30) comprises a membrane distillation reactor (31), a condensation collection tank (32) and a concentrated lithium liquid storage tank (33); the demulsification tank (22) is connected to the membrane distillation reactor (31), and the membrane distillation reactor (31) is respectively connected to the condensation collection tank (32) and the concentrated lithium liquid storage tank (33); preferably, the upper end of the demulsification tank (22) is connected to the emulsion liquid membrane preparation device (23), and the lower end of the demulsification tank (22) is connected to the membrane distillation reactor (31).

6. A method for obtaining concentrated lithium from gas field produced water, characterized in that: The steps include: Oxidative degradation of produced water; Selective extraction of lithium from produced water after oxidative degradation; The produced water after selective extraction is concentrated for lithium.

7. The method for obtaining concentrated lithium from gas field produced water according to claim 6, characterized in that: Ozone is added to oxidize and degrade the produced water.

8. A method for obtaining concentrated lithium from gas field produced water according to claim 6 or 7, characterized in that: A liquid membrane is added to perform lithium selective extraction treatment on the produced water after oxidative degradation; preferably, the volume ratio of the produced water after oxidative degradation to the volume of the liquid membrane is 0.1-5.

9. The method for obtaining concentrated lithium from gas field produced water according to claim 8, characterized in that: The preparation method of the liquid film is: Mixing ethyl acetate, surfactant, sodium tetraphenylborate, trioctyl phosphate and sodium carbonate solution; Stirring at normal temperature and pressure to homogenize and emulsify ethyl acetate, surfactant, sodium tetraphenylborate, trioctyl phosphate and sodium carbonate solution to obtain a liquid film; Preferably, the volume ratio of the ethyl acetate to the trioctyl phosphate is 1 to 5, the volume ratio of the trioctyl phosphate to the sodium tetraphenylborate is 1 to 10, the volume ratio of the organic solvent to the sodium carbonate solution is 2 to 20, and the mass fraction ratio of the ethyl acetate to the surfactant is 10 to 100; Wherein: the organic solvent comprises ethyl acetate, trioctyl phosphate, sodium tetraphenylborate and a surfactant.

10. The method for obtaining concentrated lithium from gas field produced water according to claim 9, characterized in that: The HLB value of the surfactant is 3-6.

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