A high-efficiency extraction lithium process for offshore platform produced fluid

Abstract

The application discloses a kind of high-efficiency extraction lithium extraction processes for offshore platform produced fluid, belong to lithium resource recovery technical field, the process includes the following steps: first, the produced fluid of offshore oil and gas platform is carried out depth oil removal treatment, obtain lithium-containing water phase;Then lithium-containing water phase is mixed with liquid-liquid extraction agent and is extracted, after extraction, the mixed liquid is introduced into high-efficiency oil-water separation module, obtain lithium-rich oil phase and raffinate water phase;Then lithium-rich oil phase is stripped in hydrochloric acid regeneration tank, lithium ion is transferred to hydrochloric acid phase, after stripping, the mixed liquid is separated by high-efficiency oil-water separation module in tank, and lithium chloride-rich stripping solution is obtained.The application is integrated by depth oil removal treatment, high-efficiency oil-water separation and on-line regeneration of extraction agent, effectively solves the problems of emulsification, separation difficulty and high operating cost in the process of lithium extraction from seawater on offshore platform, and the process is compact and efficient, suitable for efficient recovery of lithium resources under the working conditions of offshore platform.

Description

Technical Field

[0001] This invention belongs to the field of lithium resource recovery technology, specifically, it relates to a highly efficient extraction lithium extraction process for produced fluids from offshore platforms. Background Technology

[0002] Lithium, as a strategically critical metal, is increasingly used in batteries, ceramics, glass, aerospace, and other fields, leading to continuously growing demand and a severe supply-demand imbalance. Besides traditional brine and mineral lithium resources, offshore platform produced fluids (a typical type of marine formation brine), as an unconventional lithium resource, have attracted widespread attention due to their enormous reserves. However, offshore platform produced fluids are characterized by low lithium-ion concentrations (typically below 100 mg / L) and complex compositions (containing large amounts of sodium). + K + Ca 2 + Mg 2+ Characterized by features such as coexisting ions and oil content, it belongs to low-quality brine, and the efficient and economical extraction of lithium resources in it faces enormous challenges.

[0003] Solvent extraction is a highly efficient separation technology widely used in lithium recovery, especially the synergistic extraction system represented by tributyl phosphate-ferric chloride. This system selectively captures lithium ions through complexation reactions, offering unique advantages for treating brines with high magnesium-to-lithium ratios, achieving high lithium recovery rates even under low lithium concentration conditions. However, it has significant drawbacks when treating such low-concentration, complex waters: direct mixing and extraction easily forms stable emulsions, leading to difficulties in oil-water separation and significant extractant loss; the efficiency and cost control of back-extracting lithium from the organic phase and recycling the extractant also pose serious challenges to the environmental protection facilities of offshore platforms; traditional extraction-clarification tank systems have large floor space and long residence times, necessitating a compact, efficient, and continuously automated process on space-constrained offshore platforms. Summary of the Invention

[0004] The purpose of this invention is to overcome the deficiencies in the prior art and provide a highly efficient extraction lithium extraction process for produced fluids from offshore platforms. This process can efficiently treat marine formation brine containing low concentrations of lithium and oil, solve the emulsification problem in the extraction process, and achieve efficient regeneration and recycling of the extractant.

[0005] The objective of this invention can be achieved through the following technical solutions: This invention provides a highly efficient extraction lithium extraction process for produced fluids from offshore platforms, comprising the following steps: S1. Deeply remove oil from the produced fluid of the offshore oil and gas development platform to reduce the oil content to 5-10 mg / L or below, and obtain a lithium-containing aqueous phase; S2. The lithium-containing aqueous phase obtained in step S1 is mixed with a liquid-liquid extractant for extraction. The extracted mixture is then passed into a high-efficiency oil-water separation module to obtain a lithium-rich oil phase and a raffinate aqueous phase. S3. The lithium-rich oil phase obtained in step S2 is back-extracted in a hydrochloric acid regeneration tank, and lithium ions are transferred to the hydrochloric acid phase. The back-extracted mixture is then passed through a high-efficiency oil-water separation module in the tank to achieve oil-water separation and obtain a back-extracted liquid rich in lithium chloride.

[0006] In some embodiments of the present invention, the deep oil removal process in step S1 employs a single or combination of equipment from the following: production separator, aerated flotation unit, hydrocyclone, inclined plate separator, fine filter, and walnut shell filter.

[0007] In some embodiments of the present invention, the liquid-liquid extractant in step S2 is a composition of an extractant, a diluent, and a co-extractant.

[0008] In some embodiments of the present invention, the extractant is at least one selected from tributyl phosphate, di(2-ethylhexyl) phosphate, bis(2,4,4-trimethylpentyl)phosphonic acid, and trialkylphosphine oxide; The diluent is at least one of methyl isobutyl ketone, sulfonated kerosene, kerosene, and straight-chain alkanes; The co-extractant is ferric chloride.

[0009] Furthermore, the total amount of the extractant and diluent is calculated as 100% by volume, with the extractant having a volume fraction of 30-60% and the diluent having a volume fraction of 40-70%; the co-extractant, ferric chloride, is in the form of Fe... 3+ Calculated according to Fe 3+ With Li + The molar ratio is (1.2~1.6):1, with the addition of ferric chloride.

[0010] In some embodiments of the present invention, the volume ratio of the lithium-containing aqueous phase to the liquid-liquid extractant in step S2 is 1:(10-100), and the extraction time is 10-35 min.

[0011] In some embodiments of the present invention, the high-efficiency oil-water separation module mentioned in steps S2 and S3 is a single module or a combination of modules among the following: coalescence separation module, inclined plate sedimentation module, cyclone separation module, and electro-desorption separation module.

[0012] Furthermore, the residual aqueous phase described in step S2 is either discharged into the sea or reinjected into the formation according to the needs of the offshore platform.

[0013] In some embodiments of the present invention, the concentration of hydrochloric acid in the hydrochloric acid regeneration tank in step S3 is 3 to 6 mol / L.

[0014] In some embodiments of the present invention, after the high-efficiency oil-water separation module achieves oil-water separation in step S3, the separated oil phase is returned to the extraction process in step S2 for recycling, while the aqueous phase remains in the hydrochloric acid regeneration tank. By monitoring the pH value of the aqueous phase, when the pH value reaches a preset threshold, the hydrochloric acid in the tank is replaced to obtain a back-extraction solution rich in lithium chloride.

[0015] In some embodiments of the present invention, the preset threshold value of the pH value is 5.0 to 6.0.

[0016] In some embodiments of the present invention, the lithium chloride-rich back-extraction solution obtained in step S3 can be further processed, including but not limited to one or more of evaporation crystallization, reaction precipitation, and electrodialysis.

[0017] Compared with the prior art, the present invention has the following outstanding advantages: 1. This invention provides a high-efficiency lithium extraction process for produced fluids from offshore platforms. It utilizes a deep oil removal unit, a high-efficiency oil-water separation module, and an integrated regeneration system to achieve efficient extraction and recovery of low-concentration lithium ions and online regeneration and recycling of the extractant, thereby improving the lithium resource recovery rate while reducing operating costs.

[0018] 2. This invention is based on a process of efficient solvent extraction and rapid online regeneration of the oil phase. In the extraction stage, a specific extraction system is used to selectively capture lithium ions, thereby enhancing interphase mass transfer and deep oil-water separation. In the back-extraction and regeneration stage, the back-extraction solution is precisely replaced by real-time monitoring of the pH value. The regenerated oil-water mixture is then deeply separated to obtain a lithium-rich solution, which has the advantages of good selectivity and high degree of automation. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a high-efficiency extraction lithium extraction process for produced fluids from offshore platforms. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0021] like Figure 1As shown, this invention employs an integrated process flow of "deep oil removal - high-efficiency extraction - oil-water separation - back-extraction regeneration - product recovery". This process first performs deep oil removal on the produced fluid from the offshore platform to eliminate interference from the oil phase in subsequent extraction; then, a specific extraction system is used to selectively capture low-concentration lithium ions; a high-efficiency oil-water separation module achieves rapid separation of the two phases; the lithium-rich oil phase reacts with hydrochloric acid in a regeneration tank to achieve back-extraction, while the extractant is regenerated; the timing of back-extraction solution replacement is controlled by monitoring the pH value; finally, the lithium-rich back-extraction solution can be further processed to recover high-purity lithium products.

[0022] Example 1 A highly efficient extraction lithium extraction process for produced fluids from offshore platforms includes the following steps: S1. Deep oil removal treatment is carried out on the produced fluid of the offshore oil and gas development platform to reduce the oil content to 5-10 mg / L or below, and lithium-containing aqueous phase is obtained; the deep oil removal treatment adopts a single or combined equipment from the following: production separator, aerated flotation device, hydrocyclone, inclined plate separator, fine filter, and walnut shell filter. S2. The lithium-containing aqueous phase obtained in step S1 is mixed with the liquid-liquid extractant at a volume ratio of 1:(10-100) and extracted for 10-35 minutes. The extracted mixture is then passed into a high-efficiency oil-water separation module to obtain a lithium-rich oil phase and a raffinate aqueous phase. S3. The raffinate obtained in step S2 is discharged into the sea or reinjected into the formation according to the needs of the offshore platform. The lithium-rich oil phase obtained in step S2 is back-extracted in a hydrochloric acid regeneration tank (the concentration of hydrochloric acid is 3-6 mol / L). The lithium ions are transferred to the hydrochloric acid phase. The back-extracted mixture is then passed through a high-efficiency oil-water separation module in the tank to achieve oil-water separation. The separated oil phase is returned to the extraction process in step S2 for recycling. The aqueous phase remains in the hydrochloric acid regeneration tank. By monitoring the pH value of the aqueous phase, when the pH value reaches the preset threshold of 5.0-6.0, the hydrochloric acid in the tank is replaced to obtain a back-extracted solution rich in lithium chloride.

[0023] Furthermore, the high-efficiency oil-water separation module mentioned in steps S2 and S3 is a single module or a combination of modules among the following: coalescence separation module, inclined plate sedimentation module, cyclone separation module, and electro-desorption separation module.

[0024] Furthermore, the liquid-liquid extractant in step S2 is a composition of an extractant, a diluent, and a co-extractant.

[0025] Furthermore, the extractant is at least one selected from the following: tributyl phosphate, di(2-ethylhexyl) phosphate, bis(2,4,4-trimethylpentyl)phosphonic acid, and trialkylphosphine oxide; The diluent is at least one of methyl isobutyl ketone, sulfonated kerosene, kerosene, and straight-chain alkanes; The co-extractant is ferric chloride.

[0026] Furthermore, the total amount of the extractant and diluent is calculated as 100% by volume, with the extractant having a volume fraction of 30-60% and the diluent having a volume fraction of 40-70%; the co-extractant, ferric chloride, is in the form of Fe... 3+ Calculated according to Fe 3+ With Li + The molar ratio is (1.2~1.6):1, with the addition of ferric chloride.

[0027] Example 2 This Example 2 employs the high-efficiency extraction lithium extraction process for offshore platform produced fluids from Example 1, with the following specific parameters: In step S2: the lithium-containing aqueous phase is mixed with a liquid-liquid extractant at a volume ratio of 1:50 for extraction, and the extraction time is 25 min; the liquid-liquid extractant is a mixed solvent of 60% tributyl phosphate and 40% sulfonated kerosene, according to Fe... 3+ With Li + Ferric chloride is added at a molar ratio of 1.3:1; the mixture is then passed through a high-efficiency oil-water separation module (filled with a composite filter material of ultra-fine glass fiber and polypropylene fiber) for efficient separation. In step S3: the concentration of hydrochloric acid in the hydrochloric acid regeneration tank is 4 mol / L for back-extraction. The oil phase regeneration tank is equipped with a high-efficiency oil-water separation module (filled with a composite filter material of ultra-fine glass fiber and polypropylene fiber). When the pH value reaches the preset threshold of 5.5, the hydrochloric acid in the tank is replaced to obtain a back-extraction solution rich in lithium chloride.

[0028] Example 3 This embodiment 3 employs the high-efficiency extraction lithium extraction process for offshore platform produced fluids from embodiment 1, with the following specific parameters: In step S2: the lithium-containing aqueous phase and the liquid-liquid extractant are mixed at a volume ratio of 1:30 for extraction, and the extraction time is 35 min; the liquid-liquid extractant is a mixed solvent of 40% bis(2,4,4-trimethylpentyl)phosphonic acid and 60% n-dodecane, and is formulated according to Fe... 3+ With Li + Ferric chloride was added at a molar ratio of 1.7:1; the mixture was then introduced into a high-efficiency oil-water separation module (an inclined plate sedimentation module, which contains a set of polypropylene inclined plates with a spacing of 50 mm and an inclination angle of 60°) for efficient separation. In step S3: the concentration of hydrochloric acid in the hydrochloric acid regeneration tank is 5 mol / L for back-extraction. The oil phase regeneration tank is equipped with a high-efficiency oil-water separation module (inclined plate sedimentation module, with a set of polypropylene inclined plates with a spacing of 50 mm and an inclination angle of 60°). When the pH value reaches the preset threshold of 5.0, the hydrochloric acid in the tank is replaced to obtain a back-extraction solution rich in lithium chloride.

[0029] Performance testing The deep oil removal process of produced fluid from an offshore oil and gas field platform is as follows: production separator - hydrocyclone - aerated flotation. The oil content of the produced fluid is 39862 mg / L. After treatment by the production separator, the oil content is 257 mg / L. After treatment by the hydrocyclone, the oil content is 83 mg / L. After treatment by the aerated flotation, the oil content is reduced to 8 mg / L. Other basic physicochemical properties are shown in Table 1, and ion concentrations are shown in Table 2.

[0030] Table 1. Basic physicochemical properties of a deep oil removal unit on an offshore oil and gas field platform. Table 2. Ion concentration of produced fluid from an offshore oil and gas field platform (unit: mg / L) The treated lithium-containing aqueous phase was sequentially processed using the specific process parameters of Examples 2-3 to obtain lithium chloride-rich back-extraction solutions. These solutions were then tested and analyzed. The back-extraction solution obtained in Example 2 contained Li... + The concentration was 182.4 mg / L, and the back-extraction solution Li obtained in Example 3 was... + The concentration was 158.7 mg / L.

[0031] Data shows that even with oil-to-water ratios of 1:30 or even 1:50, Examples 2 and 3 can still effectively enrich lithium resources from low-concentration lithium-containing aqueous phases, increasing the lithium concentration in the back-extraction solution from 5.6 mg / L in the original solution to 182.4 mg / L and 158.7 mg / L, respectively. The tributyl phosphate system in Example 2 exhibits superior lithium enrichment compared to Example 3, demonstrating its stronger extraction capability for low-concentration lithium ions. Therefore, the process of this invention can operate stably under large oil-to-water ratios, possessing strong ratio adaptability and engineering application potential. The ratio parameters can be flexibly adjusted according to actual platform space and equipment conditions to achieve efficient recovery of lithium resources.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present application in any way. Although the present application discloses the preferred embodiment as described above, it is not intended to limit the present application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A highly efficient extraction lithium extraction process for produced fluids from offshore platforms, characterized in that, Includes the following steps: S1. Deeply remove oil from the produced fluid of the offshore oil and gas development platform to reduce the oil content to 5-10 mg / L or below, and obtain a lithium-containing aqueous phase; S2. The lithium-containing aqueous phase obtained in step S1 is mixed with a liquid-liquid extractant for extraction. The extracted mixture is then passed into a high-efficiency oil-water separation module to obtain a lithium-rich oil phase and a raffinate aqueous phase. S3. The lithium-rich oil phase obtained in step S2 is back-extracted in a hydrochloric acid regeneration tank, and lithium ions are transferred to the hydrochloric acid phase. The back-extracted mixture is then passed through a high-efficiency oil-water separation module in the tank to achieve oil-water separation and obtain a back-extracted liquid rich in lithium chloride.

2. The high-efficiency lithium extraction process according to claim 1, characterized in that, The deep oil removal process described in step S1 uses a single or combination of equipment from the following: production separator, aerated flotation unit, hydrocyclone, inclined plate separator, fine filter, and walnut shell filter.

3. The high-efficiency lithium extraction process according to claim 1, characterized in that, The liquid-liquid extractant mentioned in step S2 is a composition of an extractant, a diluent, and a co-extractant.

4. The high-efficiency lithium extraction process according to claim 3, characterized in that, The extractant is at least one of tributyl phosphate, di(2-ethylhexyl) phosphate, bis(2,4,4-trimethylpentyl)phosphonic acid, and trialkylphosphine oxide; The diluent is at least one of methyl isobutyl ketone, sulfonated kerosene, kerosene, and straight-chain alkanes; The co-extractant is ferric chloride.

5. The high-efficiency lithium extraction process according to claim 4, characterized in that, The total amount of the extractant and diluent is calculated as 100% by volume, with the extractant having a volume fraction of 30-60% and the diluent a volume fraction of 40-70%; the co-extractant is Fe 3+ Calculated according to Fe 3+ With Li + The molar ratio is (1.2~1.6):1 with the addition of a co-extractant.

6. The high-efficiency lithium extraction process according to claim 1, characterized in that, In step S2, the volume ratio of the lithium-containing aqueous phase to the liquid-liquid extractant is 1:(10-100), and the extraction time is 10-35 min.

7. The high-efficiency lithium extraction process according to claim 1, characterized in that, The high-efficiency oil-water separation module mentioned in steps S2 and S3 is a single module or a combination of modules among the following: coalescence separation module, inclined plate sedimentation module, cyclone separation module, and electro-desorption separation module.

8. The high-efficiency extraction lithium extraction process according to claim 1, characterized in that, The concentration of hydrochloric acid in the hydrochloric acid regeneration tank mentioned in step S3 is 3-6 mol / L.

9. The high-efficiency extraction lithium extraction process according to claim 1, characterized in that, After the high-efficiency oil-water separation module separates the oil and water in step S3, the separated oil phase is returned to the extraction process in step S2 for recycling, while the aqueous phase remains in the hydrochloric acid regeneration tank. By monitoring the pH value of the aqueous phase, when the pH value reaches the preset threshold, the hydrochloric acid in the tank is replaced to obtain a back-extraction solution rich in lithium chloride.

10. The high-efficiency extraction lithium extraction process according to claim 8, characterized in that, The preset threshold for the pH value is 5.0 to 6.0.

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