System for extracting lithium from salt lake brine and oil and gas field produced water based on extraction method

Abstract

The utility model provides a system for extracting lithium from salt lake brine and oil and gas field produced water based on an extraction method, which comprises a treatment system including a pretreatment unit, an evaporation unit and an extraction unit, the pretreatment unit comprises a first water inlet pump, the evaporation unit comprises an evaporation water inlet tank and an evaporation tank, and the extraction unit comprises a second water inlet pump. The extraction unit comprises an evaporation mother liquor tank, an N-stage extraction machine, an extraction agent tank, an extraction intermediate tank, a tail brine tank, an N-stage back-extraction machine, an acid tank and a qualified liquid tank, so that the extraction efficiency is greatly improved through the N-stage extraction machine and the N-stage back-extraction machine, and meanwhile, the pollution of lithium extraction to the environment is also reduced; the lithium extraction system based on the extraction method is high in lithium extraction efficiency, short in technological process, simple in operation process, high in continuity, high in automation degree and environmentally friendly, and a new thought is provided for the lithium extraction process.

Description

Technical Field

[0001] The utility model relates to the field of extracting lithium from the original brine of salt lake brine and oil and gas field produced water containing lithium, and particularly relates to a lithium extraction system for salt lake brine and oil and gas field produced water based on the extraction method. Background Technique

[0002] At present, the methods for extracting lithium from brine include extraction method, adsorption method, precipitation method, electrodialysis method, solar pond method, etc. Among them, the lithium extraction technology by the extraction method has the outstanding advantages of high selectivity, high lithium extraction efficiency, short process flow, simple operation process, strong continuity, high automation degree, less energy consumption, low investment cost, etc., and is expected to obtain a larger market share in the salt lake lithium extraction industry, with broad future development space.

[0003] However, the existing extraction process is cumbersome, the extraction structure is complex, the maintenance cost is high, and the extraction efficiency is not satisfactory. Summary of the Invention

[0004] Purpose of the Invention: Aiming at the deficiencies of the above-mentioned existing technologies, a lithium extraction system for salt lake brine and oil and gas field produced water based on the extraction method is proposed;

[0005] Technical Solution:

[0006] A lithium extraction system for salt lake brine and oil and gas field produced water based on the extraction method, characterized in that it includes a pretreatment unit, an evaporation unit, and an extraction unit:

[0007] The pretreatment unit includes a first water inlet pump, the outlet of the first water inlet pump is connected to the inlet of a multi-media filter, the outlet of the multi-media filter is connected to the inlet of a first reaction tank, the first reaction tank is communicated with a second reaction tank through a water passing hole, a chemical dosing port is also provided on one side of the second reaction tank, the second reaction tank is also connected to a sedimentation tank or a flotation tank, an overflow tank is arranged at the upper part of the sedimentation tank or the flotation tank and is connected to a clear liquid tank, the clear liquid tank is connected to a second water inlet pump of a tubular ultrafiltration membrane TUF unit, the concentrated liquid outlet pipe of the tubular ultrafiltration membrane TUF unit is connected to the upper part inlet pipe of the clear liquid tank, and the produced water outlet pipe of the tubular ultrafiltration membrane TUF unit is connected to the evaporation unit;

[0008] The evaporation unit includes an evaporation water inlet tank and an evaporation tank, the produced water outlet pipe of the tubular ultrafiltration membrane TUF unit is connected to the evaporation water inlet tank, the evaporation water inlet tank is connected to the water inlet of the evaporation tank through a third water inlet pump and a pipeline, a steam inlet is opened at the top of the evaporation tank, the steam generated by the boiler room is connected to the inner cylinder of the evaporation tank through the steam inlet, the outlet of the inner cylinder of the evaporation tank is placed below the liquid level of the evaporation tank, the bottom outlet of the evaporation tank is connected to a circulation pump, a tee is arranged at the outlet of the circulation pump, one pipeline of the tee is connected to the extraction unit, and the other pipeline is connected to the water inlet of the evaporation tank.

[0009] The described extraction unit includes an evaporation mother liquor tank, an N-stage extractor, an extractant tank, an extraction intermediate tank, a tail brine tank, a multi-stage back-extractor, an acid tank, and a qualified liquid tank. One pipeline of the three-way connection leads to the evaporation mother liquor tank. The bottom of the evaporation mother liquor tank is connected to the heavy phase inlet of the first stage of the N-stage extractor through a first feed pump and a pipeline. The bottom of the extractant tank is connected to the light phase inlet of the first stage of the N-stage extractor through a second feed pump and a pipeline. The heavy phase outlet of the first stage of the extractor is connected to the heavy phase inlet of the next stage of the extractor through a pipeline. The light phase outlet of the first stage of the extractor is connected to the light phase inlet of the next stage of the extractor through a pipeline. The light phase outlet of the last stage of the extractor is connected to the top inlet of the extraction intermediate tank. The heavy phase outlet of the last stage of the extractor is connected to the tail brine tank; s

[0010] The bottom of the extraction intermediate tank is connected to the light phase inlet of the first stage of the N-stage back-extractor through a third feed pump and a pipeline. The bottom of the acid tank is connected to the heavy phase inlet of the first stage of the back-extractor through a fourth feed pump and a pipeline. The heavy phase outlet of the first stage of the extractor is connected to the heavy phase inlet of the next stage of the back-extractor through a pipeline. The light phase outlet of the first stage of the extractor is connected to the light phase inlet of the next stage of the back-extractor through a pipeline. The light phase outlet of the last stage of the back-extractor is connected to the top inlet of the extractant tank. The heavy phase outlet of the last stage of the back-extractor is connected to the qualified liquid tank.

[0011] Preferably, the evaporation tank adopts an MVR evaporator or a low-temperature evaporator.

[0012] Preferably, the value of N is: 3 ≤ N ≤ 10.

[0013] Preferably, the materials of the N-stage extractor and the N-stage back-extractor are both carbon steel, and the inner parts of all equipment and pipeline connectors are lined with tetrafluoro materials.

[0014] Beneficial effects: The present utility model greatly improves the extraction efficiency through the N-stage extractor and the N-stage back-extractor. At the same time, it reduces the environmental pollution caused by lithium extraction by extraction, and also greatly reduces the loss of extractant and equipment. Description of the Drawings

[0015] Figure 1 is the process flow chart of the present utility model;

[0016] Figure 2 is the extraction flow chart of the present utility model;

[0017] Figure 3 is the pre-treatment equipment drawing of the present utility model;

[0018] Figure 4 is the evaporation equipment drawing of the present utility model;

[0019] Figure 5 This is the extraction equipment diagram of the present utility model. Specific embodiments

[0020] The following further explains the present utility model in conjunction with the attached drawings.

[0021] A lithium extraction system for salt lake brine and oil and gas field produced water based on the extraction method, characterized in that: it includes a treatment system including a pretreatment unit, an evaporation unit, and an extraction unit. The salt lake brine and oil and gas field produced water are pretreated according to their water quality characteristics to remove suspended solids, oil-containing compounds, and other organic matters in the water, and then enter the evaporation unit for preliminary concentration of the brine to increase the lithium concentration in the raw brine, while removing part of the sodium and potassium ions to improve the lithium ion grade in the raw brine. The brine after concentration and separation enters the extraction unit, and by using the high selectivity of the extractant, through the method of multi-stage countercurrent extraction and stripping, the Li in the brine + is transferred to the aqueous phase to complete the lithium extraction work.

[0022] The pretreatment described above includes: (1) sand filtration; (2) adding FeCl3 with a mass ratio of 1.5%, adjusting the pH to about 7, and removing suspended solids through air flotation; (3) adding FeCl3 with a mass ratio of 1.5%, adjusting the pH to about 7, adding powdered activated carbon with a mass ratio of 1‰, and then removing suspended solids through the TUF membrane. The pretreatment method used adopts one or more of the three methods according to the water quality of the water sample.

[0023] The evaporator in the evaporation unit adopts one or several of several evaporators such as MVR evaporator and multi-effect evaporator.

[0024] The tubular ultrafiltration membrane TUF unit belongs to the prior art and will not be introduced in detail here;

[0025] The evaporation unit concentrates the brine by 3 to 5 times to increase the lithium concentration in the brine and improve the subsequent extraction efficiency;

[0026] As Figure 2 shown, the extraction method used in the extraction unit is n-stage countercurrent extraction, 3 ≤ n ≤ 10. The process is that the brine and the extractant enter the bottom of the centrifugal extractor in opposite directions. After being stirred and mixed by the stirring device at the bottom of the centrifugal extractor, they rise to the separation area. Driven by the centrifugal force provided by the centrifugal device, the heavy phase, that is, the aqueous phase, flows out of the distal water outlet in the equipment and enters the next stage, and the light phase, that is, the oil phase, flows out of the proximal water outlet in the equipment and enters the next stage. The next stage repeats the process of the first stage.

[0027] As Figure 5 shown, the structures of the N-stage extractor and the N-stage stripper are the same, and both include a light phase outlet, a light phase inlet, a heavy phase outlet, and a heavy phase inlet.

[0028] The extractant used in the extraction unit is an ionic liquid with environmental friendliness, excellent chemical stability, good electrical conductivity, and extremely strong solubility, such as one or more of pyrrole-based hexafluorophosphates and imidazole-based hexafluorophosphates; the diluent is one or more of organic solvents such as sulfonated kerosene, dichloromethane, sulfurized kerosene, and petroleum ether.

[0029] In the extraction feed system, the volume ratio of the extractant to the brine is 1:2 to 1:5;

[0030] The centrifugal extractor uses carbon steel as the main body, and the inner part of the equipment and the pipeline connectors are lined with tetrafluoro materials, which increases the overall strength of the equipment while meeting the anti-corrosion requirements;

[0031] The extraction temperature is 20 - 30 °C, the single-stage extraction time is 5 - 30 min, the mixing and stirring speed is 1000 - 2000 r / min, and the centrifugal stirring speed is 300 - 2000 r / min;

[0032] The stripping agent is an acid solution containing H + with a concentration of 0.6 mol / L;

[0033] The acid solution is one or more of inorganic acids: carbonic acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and organic acids: formic acid, acetic acid, oxalic acid, etc.

[0034] Implementation method: The brine is pumped from the raw water tank to the multi-media filter, and the large-particle suspended solids in the brine are removed by sand filtration. Then it enters the multi-functional combined pool. FeCl3 solution is added to combined pool 1 while stirring, and liquid caustic soda is added to combined pool 2 while stirring to adjust the pH. The bottoms of combined pool 1 and 2 are connected. Then the brine overflows to combined pool 3 for precipitation through the overflow pipe, and the supernatant overflows to combined pool 4. The water outlet at the bottom of combined pool 4 is connected to the TUF inlet water pump, and the TUF outlet water pump sends it to the evaporator. After the brine is evaporated and concentrated, the water outlet at the bottom enters the multi-stage extraction equipment in the form of the heavy phase, and the light phase liquid of the extraction equipment is stripped with the acid solution to obtain the lithium solution.

[0035] Example 1

[0036] The lithium concentration in the oilfield water in a certain area of Xinjiang is 80.13 mg / L. After adding FeCl3 to adjust the pH at the front-end inlet and filtering through the TUF membrane, the oil-containing compounds, suspended solids, and part of the organic matter in the water are removed. Then it passes through the boron removal resin tank at a flow rate of 5 BV / h, removing 98% of the boron in the oilfield water. After that, it passes through the MVR evaporator to concentrate Li + to 370 mg / L, and a lithium solution is obtained after three-stage countercurrent extraction. The volume ratio of the extractant to the oilfield water is 1:5, and the three-stage countercurrent extraction efficiency reaches 98.6%.

[0037] Example 2

[0038] The brine of a certain salt lake in Tibet is 430 mg / L. When using titanium-based adsorbents, due to the low alkalinity, a large amount of alkali is consumed and the cost is high. The high magnesium content in the brine causes the aluminum-based adsorbent to be unable to desorb fully. After the front-end influent passes through sand filtration, it flows through the boron removal resin tank at a flow rate of 5 BV / h, reducing the boron content in the brine to below 10 mg / L. After 10-stage countercurrent extraction, a lithium solution is obtained. The volume ratio of the extractant to the brine is 1:2, and the extraction efficiency reaches 96.7%.

[0039] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A lithium extraction system for salt lake brine and oil and gas field produced water based on extraction method, characterized by: Including pretreatment unit, evaporation unit, extraction unit: The pretreatment unit comprises a first water inlet pump, the outlet of the first water inlet pump is connected to the inlet of the multi-media filter, the outlet of the multi-media filter is connected to the inlet of the first reaction tank, the first reaction tank is connected to the second reaction tank through a water hole, one side of the second reaction tank is also provided with a dosing port, the second reaction tank is also connected to a sedimentation tank or a flotation tank, an overflow tank is arranged on the upper part of the sedimentation tank or the flotation tank and connected to a clear liquid tank, the clear liquid tank is connected to the second water inlet pump of the tubular ultrafiltration membrane TUF unit, the concentrated liquid outlet pipe of the tubular ultrafiltration membrane TUF unit is connected to the upper water inlet pipe of the clear liquid tank, and the produced water outlet pipe of the tubular ultrafiltration membrane TUF unit is connected to the evaporation unit; The evaporation unit comprises an evaporation water inlet tank and an evaporation tank, the water outlet pipe of the tubular ultrafiltration membrane TUF unit is connected to the evaporation water inlet tank, the evaporation water inlet tank is connected to the water inlet of the evaporation tank through a third water inlet pump and a pipeline, a steam inlet is provided on the top of the evaporation tank, the steam generated in the boiler room is connected to the inner cylinder of the evaporation tank through the steam inlet, the outlet of the inner cylinder of the evaporation tank is placed below the liquid level of the evaporation tank, the bottom outlet of the evaporation tank is connected to the circulation pump, the circulation pump outlet is provided with a tee, one pipeline of the tee is connected to the extraction unit, and the other pipeline is connected to the water inlet of the evaporation tank; The extraction unit comprises an evaporation mother liquid tank, an N-stage extractor, an extractant tank, an extraction intermediate tank, a tail halogen tank, an N-stage stripping machine, an acid tank, and a qualified liquid tank. A pipeline of the three-way connection is connected to the evaporation mother liquid tank. The bottom of the evaporation mother liquid tank is connected to the heavy phase inlet of the first-stage extractor of the N-stage extractor through a first feed pump and a pipeline. The bottom of the extractant tank is connected to the light phase inlet of the first-stage extractor of the N-stage extractor through a second feed pump and a pipeline. The heavy phase outlet of the first-stage extractor is connected to the heavy phase inlet of the next-stage extractor through a pipeline. The light phase outlet of the first-stage extractor is connected to the light phase inlet of the next-stage extractor through a pipeline. The light phase outlet of the last-stage extractor is connected to the top inlet of the extraction intermediate tank, and the heavy phase outlet of the last-stage extractor is connected to the tail halogen tank. The bottom of the extraction intermediate tank is connected to the light phase inlet of the first-stage stripper of the N-stage stripper through the third feed pump and the pipeline, the bottom of the acid tank is connected to the heavy phase inlet of the first-stage stripper through the fourth feed pump and the pipeline, the heavy phase outlet of the first-stage extractor is connected to the heavy phase inlet of the next-stage stripper through a pipeline, the light phase outlet of the first-stage extractor is connected to the light phase inlet of the next-stage stripper through a pipeline, the light phase outlet of the last-stage stripper is connected to the top inlet of the extractant tank, and the heavy phase outlet of the last-stage stripper is connected to the qualified liquid tank.

2. A lithium extraction system for salt lake brine and oil and gas field produced water based on extraction method as claimed in claim 1, characterized in that: The evaporation tank adopts an MVR evaporator or a low-temperature evaporator.

3. A lithium extraction system for salt lake brine and oil and gas field produced water based on extraction method as claimed in claim 1, characterized in that: The value of N is: 3≤N≤10.

4. A lithium extraction system for salt lake brine and oil and gas field produced water based on extraction method as claimed in claim 1, characterized in that: The materials of N-level extractor and N-level stripper are both carbon steel.

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