Purification method and system for extracting lithium from oilfield brine to obtain high-impurity lithium-rich liquid

Abstract

The invention belongs to the technical field of extraction of lithium from oilfield brine, and discloses a purification method and system for extraction of lithium from oilfield brine and high-impurity lithium-rich liquid. The purification method comprises the following steps: step 1, adding a sodium hydroxide solution into the high-impurity lithium-rich liquid to adjust the pH value, then adding a sodium carbonate solution, carrying out stirring reaction, and carrying out plate-frame pressure filtration to obtain filter residues and filtrate; step 2, performing ceramic ultrafiltration on the filtrate to obtain produced water and concentrated water, and returning the concentrated water to the step 1 to participate in the stirring reaction again; and step 3, regulating the pH value of the produced water with hydrochloric acid, using the regulated produced water as an adsorption stock solution, and adsorbing and desorbing the adsorption stock solution with an aluminum adsorbent to obtain a purified lithium-rich solution. According to the method, aiming at the situation that a large amount of divalent metal ion impurities such as calcium and manganese are contained in the oil field brine lithium extraction lithium-rich liquid, after preliminary impurity removal is carried out through chemical precipitation, deep impurity removal is carried out in combination with ceramic ultrafiltration and the aluminum adsorbent, the service life of the ceramic ultrafiltration and the aluminum adsorbent can be effectively prolonged, and the recycling of ceramic ultrafiltration concentrated water can also improve the yield of lithium ions.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium extraction from oilfield brine, and in particular relates to a method and system for purifying high-doped lithium-rich liquid extracted from oilfield brine. Background Art

[0002] my country's lithium salt production is mainly based on lithium-containing ores such as spodumene and lepidolite, but the domestic lithium ore resources are of low grade and heavily dependent on imports. Compared with lithium extraction from ores, lithium extraction from salt lakes has obvious cost advantages. In addition to the above-mentioned ores and salt lake lithium resources, oilfield brine with useful components reaching industrial grade is also a liquid resource with development potential. Oilfield brine contains mineral resources such as lithium, potassium, boron, and bromine, and has potential resource utilization value. The development of lithium extraction technology from oilfield brine has great economic value.

[0003] The new process for extracting lithium from oilfield brine currently developed in the industry is: using manganese-based adsorbents to adsorb lithium in underground oilfield brine in an alkaline environment, desorbing lithium-rich liquid in an acidic environment, and purifying and concentrating the lithium-rich liquid to make lithium carbonate or lithium hydroxide according to the type of battery production. The purification of lithium-rich liquid is the key to determining the quality of the finished product. The lithium-rich liquid after desorption by manganese-based adsorbents contains a large amount of impurities such as calcium, magnesium, and manganese. The existing process uses aluminum-based adsorbents and ultrafiltration to remove these impurities, but the following problems are found in actual application:

[0004] 1) Aluminum-based adsorbents frequently passivate during use, that is, aluminum-based adsorbents are easily adsorbed by impurity ions such as calcium, magnesium, and manganese in lithium-rich solution and become ineffective, affecting the normal operation of aluminum-based adsorbents;

[0005] 2) The lithium-rich liquid is filtered through ceramic ultrafiltration to produce two streams of water. The concentrated water stream is continuously circulated and concentrated, and the concentration increases rapidly, resulting in blockage of the concentrated water control pipeline and the ceramic tube, which requires frequent cleaning and is difficult to operate for a long time;

[0006] 3) The concentrated water flow generated by ceramic ultrafiltration is not utilized but directly discharged to the downstream treatment device. The concentrated water flow contains more than 3,000 mg of lithium ions, resulting in the loss and waste of lithium resources.

[0007] Therefore, how to solve the above problems is a difficult problem that needs to be solved urgently in actual production. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a method and system for purifying high-impurity lithium-rich liquid from oilfield brine in view of the shortcomings of the prior art. After preliminary impurities are removed by chemical precipitation, ceramic ultrafiltration and aluminum-based adsorbents are used for deep impurity removal, which can effectively extend the service life of ceramic ultrafiltration and aluminum-based adsorbents. The reuse of ceramic ultrafiltration concentrated water can also increase the yield of lithium ions.

[0009] In order to solve the technical problem proposed by the present invention, the present invention provides a method for purifying high-impure lithium-rich liquid from oilfield brine, comprising the following steps:

[0010] Step 1, adding sodium hydroxide solution to the high-doped lithium-rich solution to adjust the pH, then adding sodium carbonate solution, stirring for reaction, and filtering through a plate and frame filter to obtain a filter residue and a filtrate;

[0011] Step 2, the filtrate is subjected to ceramic ultrafiltration to obtain two water streams, namely, produced water and concentrated water. The concentrated water is returned to step 1 to participate in the stirring reaction again;

[0012] Step 3, the produced water is used as the adsorption stock solution after adjusting the pH with hydrochloric acid, and is adsorbed and desorbed by an aluminum-based adsorbent to obtain a purified lithium-rich solution.

[0013] In the above scheme, the highly impure lithium-rich liquid is a lithium chloride solution containing divalent metal ion impurities obtained by adsorbing and desorbing oilfield brine with a manganese-based adsorbent, wherein Li + The content is 2000-3500mg / L, Ca 2+ The content is 1000-4000mg / L, Mg 2+ The content is 200-500mg / L, Mn 2+ The content is 2000-2600mg / L.

[0014] In the above scheme, the pH of the sodium hydroxide solution is adjusted to 7.5-11.5, preferably to 10-11.5.

[0015] In the above scheme, the sodium carbonate solution is a saturated sodium carbonate solution at 10-35° C., and the amount of sodium carbonate is 1-1.003 times the amount of calcium ion substance in the high-doped lithium-rich solution.

[0016] In the above scheme, the stirring rate of the stirring reaction is 20-50r / min, and the reaction time is 2-3h.

[0017] In the above scheme, the Li + The content is 2000-3500mg / L, Ca 2+ The content is 375-600mg / L, Mg 2+ The content is 30-60mg / L, Mn 2+ The content is 300-390mg / L.

[0018] In the above scheme, the pore size of the ultrafiltration membrane used in the ceramic ultrafiltration is 30-60nm.

[0019] In the above scheme, the Li in the produced water + The content is 2000-3500mg / L, Ca 2+ Content ≤1mg / L, Mg2+ Content ≤1mg / L, Mn 2+ Content ≤1mg / L.

[0020] In the above scheme, the hydrochloric acid is used to adjust the pH to 5-6.

[0021] In the above scheme, the specific process of adsorption and desorption of the aluminum-based adsorbent is:

[0022] 1) Start-up cycle: the adsorption stock solution is adsorbed by the aluminum adsorbent, and then the aluminum adsorbent is eluted with pure water to obtain an eluent; then desorbed with pure water to obtain a desorbed liquid; and finally washed with pure water to obtain a washing liquid;

[0023] 2) Formal cycle: The eluent and the adsorption stock solution are sequentially adsorbed by the aluminum adsorbent, and then the aluminum adsorbent is firstly eluted with the cleaning solution to obtain the eluent; then it is desorbed with pure water to obtain the desorption solution; finally, it is cleaned with pure water to obtain the cleaning solution; and this cycle of operations is subsequently repeated.

[0024] Furthermore, the pH of the pure water is 5-6. Adjusting the pH of the water to be weakly acidic can prevent the passivation of the adsorbent in the aluminum adsorption tower.

[0025] Furthermore, the operating temperature of the adsorption, elution, desorption and cleaning processes is 10-35°C.

[0026] Furthermore, the flow rate of the eluent flowing through the aluminum-based adsorbent is 1-2.5 BV / h, and the flow rate of the adsorption stock solution flowing through the aluminum-based adsorbent is 0.6-1 BV / h.

[0027] Furthermore, the elution flow rate is 1-2BV / h, and the elution time is 2000-2500s.

[0028] Furthermore, the desorption flow rate is 1-2 BV / h, and the desorption time is 4080-5000s.

[0029] Furthermore, the cleaning flow rate is 1-2BV / h, and the cleaning time is 2040-3000s.

[0030] In the above scheme, the purified lithium-rich solution contains Li + The content is 450-600mg / L, Ca 2+ Content ≤0.05mg / L, Mg 2+ Content ≤0.05mg / L, Mn 2+ Content ≤0.05mg / L.

[0031] The present invention also provides a purification system for extracting lithium from oilfield brine to obtain high-doped lithium-rich liquid, comprising: a chemical precipitation device, a ceramic ultrafiltration device and an adsorption and desorption device.

[0032] In the above scheme, the chemical precipitation device includes a reaction tank, a plate and frame filter press and a filtrate tank. The high-impurity lithium-rich liquid enters the inlet of the reaction tank through a pipeline. A stirring device is provided in the reaction tank. The outlet of the reaction tank is connected to the inlet of the plate and frame filter press. The water output outlet of the plate and frame filter press is connected to the inlet of the filtrate tank. The outlet of the filtrate tank is connected to the ceramic ultrafiltration device; the chemical precipitation device also includes a sodium hydroxide dosing tank and a sodium carbonate dosing tank. The sodium hydroxide dosing tank is connected to the inlet pipeline of the reaction tank, and the sodium carbonate dosing tank is connected to the reaction tank.

[0033] In the above scheme, the ceramic ultrafiltration device includes an ultrafiltration membrane unit and a water production tank; the inlet of the ceramic ultrafiltration membrane unit is connected to the outlet of the filtrate tank, and the concentrated water outlet of the ceramic ultrafiltration membrane unit is connected to the inlet of the reaction tank through a reflux pipe, so that the ceramic ultrafiltration concentrated water is returned to the reaction tank for recycling, the water production outlet of the ceramic ultrafiltration membrane unit is connected to the inlet of the water production tank, and the outlet of the water production tank is connected to the adsorption and desorption device.

[0034] In the above scheme, the adsorption and desorption device includes a raw liquid tank and an adsorption tower, the inlet of the raw liquid tank is connected to the outlet of the water production tank, and the outlet of the raw liquid tank is connected to the inlet of the adsorption tower; the adsorption and desorption device also includes a hydrochloric acid dosing tank, and the hydrochloric acid dosing tank is connected to the inlet pipe of the raw liquid tank; the adsorption and desorption device also includes a leaching liquid tank, a desorption liquid tank and a cleaning liquid tank, and the outlet of the aluminum-based adsorption tower is respectively connected to the leaching liquid tank, the desorption liquid tank and the cleaning liquid tank, for storing the leaching liquid, desorption liquid and cleaning liquid in the desorption process; the leaching liquid tank and the cleaning liquid tank are both connected to the inlet of the adsorption tower through a reflux pipe, for returning the leaching liquid and the cleaning liquid to the adsorption tower for recycling.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1) The present invention aims at extracting lithium from oilfield brine, in which a large amount of divalent metal ion impurities such as calcium and manganese are contained in the lithium-rich liquid. A chemical method is first used to precipitate most of the metal ion impurities, and the metal ion impurities are removed along with the slag through plate and frame filter pressing, so that the metal ion impurities content in the obtained filtrate is greatly reduced. The filtrate is then subjected to ceramic ultrafiltration and aluminum-based adsorbent for deep impurity removal in sequence. On the one hand, the adverse effects of metal ion impurities on the ceramic ultrafiltration and aluminum-based adsorbent are greatly reduced, and the service life of the ceramic ultrafiltration and aluminum-based adsorbent is effectively extended. On the other hand, the concentrated water of the ceramic ultrafiltration is prevented from being reused, thereby improving the yield of lithium ions in the entire system.

[0037] 2) In the process of adsorption and desorption of aluminum-based adsorbents, the recycling of eluent and cleaning liquid can further improve the yield of lithium ions and reduce the discharge of wastewater. In addition, adjusting the pH of the desorption water to a weak acid can effectively prevent the passivation of the adsorbent in the aluminum-based adsorption tower, which is beneficial to the desorption process and further extends the service life of the aluminum-based adsorbent. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the purification system for extracting lithium from oilfield brine to obtain high-doped lithium-rich liquid according to the present invention.

[0039] Explanation of the accompanying drawings: 1-reaction tank; 2-plate and frame filter press; 3-filtrate tank; 4-sodium hydroxide dosing tank; 5-sodium carbonate dosing tank; 6-ultrafiltration membrane unit; 7-water production tank; 8-raw liquid tank; 9-hydrochloric acid dosing tank; 10-adsorption tower; 11-elution liquid tank; 12-desorption liquid tank; 13-cleaning liquid tank. DETAILED DESCRIPTION

[0040] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0041] In the following examples, the aluminum-based adsorbent used is cylindrical particles with a diameter of 0.9-1.1 mm, a length of 1-2.5 mm, and a lithium ion exchange capacity of ≥2.5 g / L.

[0042] Example 1

[0043] A purification system for extracting lithium from oilfield brine with high impurity lithium-rich liquid, such as Figure 1 As shown, it includes: a chemical precipitation device, a ceramic ultrafiltration device and an adsorption and desorption device.

[0044] The chemical precipitation device includes a reaction tank 1, a plate and frame filter press 2 and a filtrate tank 3. The high-impurity lithium-rich liquid enters the reaction tank 1 from the inlet through a pipeline. A stirring device is provided in the reaction tank 1. The outlet of the reaction tank 1 is connected to the inlet of the plate and frame filter press 2. The water output outlet of the plate and frame filter press 2 is connected to the inlet of the filtrate tank 3. The outlet of the filtrate tank 3 is connected to a ceramic ultrafiltration device. The chemical precipitation device also includes a sodium hydroxide dosing tank 4 and a sodium carbonate dosing tank 5. The sodium hydroxide dosing tank 4 is connected to the inlet pipeline of the reaction tank 1, and the sodium carbonate dosing tank 5 is connected to the reaction tank 1.

[0045] The ceramic ultrafiltration device includes an ultrafiltration membrane unit 6 and a water production tank 7; the inlet of the ceramic ultrafiltration membrane unit 6 is connected to the outlet of the filtrate tank 3, and the concentrated water outlet of the ceramic ultrafiltration membrane unit 6 is connected to the inlet of the reaction tank 1 through a reflux pipe, so that the ceramic ultrafiltration concentrated water returns to the reaction tank 1 for recycling, the water production outlet of the ceramic ultrafiltration membrane unit 6 is connected to the inlet of the water production tank 7, and the outlet of the water production tank 7 is connected to the adsorption and desorption device.

[0046] The adsorption and desorption device includes a raw liquid tank 8 and an adsorption tower 10, the inlet of the raw liquid tank 8 is connected to the outlet of the water production tank 7, and the outlet of the raw liquid tank 8 is connected to the inlet of the adsorption tower 10; the adsorption and desorption device also includes a hydrochloric acid dosing tank 9, which is connected to the inlet pipe of the raw liquid tank 8; the adsorption and desorption device also includes a washing liquid tank 11, a desorption liquid tank 12 and a cleaning liquid tank 13, and the outlet of the aluminum-based adsorption tower 10 is respectively connected to the washing liquid tank 11, the desorption liquid tank 12 and the cleaning liquid tank 13, which are used to store the washing liquid, desorption liquid and cleaning liquid in the desorption process; the washing liquid tank 11 and the cleaning liquid tank 13 are both connected to the inlet of the adsorption tower 10 through a reflux pipe, which are used to return the washing liquid and the cleaning liquid to the adsorption tower for recycling.

[0047] Example 2

[0048] The brine of an oil field was adsorbed and desorbed by a manganese adsorbent to obtain a highly impure lithium-rich solution, in which Li + The content is 2609mg / L, Ca 2+ The content is 3569mg / L, Mg 2+ The content is 215.7mg / L, Mn 2+ The content is 2322mg / L.

[0049] This embodiment uses the system of embodiment 1 to purify the high-doped lithium-rich solution, including the following steps:

[0050] Step 1, the high-doped lithium-rich liquid enters the reaction tank through a pipeline, a sodium hydroxide solution with a mass concentration of 30% is added into the pipeline through a sodium hydroxide dosing tank to adjust the pH to 10, and then a 20° C. saturated sodium carbonate solution is added into the reaction tank through a sodium carbonate dosing tank, the amount of sodium carbonate added is 1.003 times the amount of calcium ion substance in the high-doped lithium-rich liquid, the stirring device in the reaction tank is started, and the reaction is carried out at a stirring rate of 50r / min for 3h, the reaction solution is transported to a plate and frame filter press for filtration, the filter residue is discharged, and the filtrate is collected into a filtrate tank;

[0051] Step 2, the filtrate in the filtrate tank is transported to the ceramic ultrafiltration membrane unit. The pore size of the ultrafiltration membrane used is 50nm. Two water flows are generated after ultrafiltration. The concentrated water is returned to the reaction tank through the reflux pipe for recycling, and the produced water is collected in the water production tank;

[0052] Step 3, the water produced from the water production tank is adjusted to pH 5 by adding hydrochloric acid through the hydrochloric acid dosing tank, and then stored in the stock liquid tank as the adsorption stock solution, and then transported from the stock liquid tank to the adsorption tower for adsorption and desorption, and the obtained desorption liquid is the purified lithium-rich liquid; the specific process of adsorption and desorption is:

[0053] 1) Start-up cycle: Under 20°C conditions, the adsorption stock solution in the stock solution tank flows through the adsorption tower at a flow rate of 0.8BV / h for adsorption for 2400s; then, pure water flows through the adsorption tower at a flow rate of 1.27BV / h for elution for 2000s, and the eluent is discharged and stored in the eluent tank; then, pure water flows through the adsorption tower at a flow rate of 1.63BV / h for desorption for 4080s, and the desorption liquid is discharged and stored in the desorption liquid tank; finally, pure water flows through the adsorption tower at a flow rate of 1.63BV / h for cleaning for 2040s, and the cleaning liquid is discharged and stored in the cleaning liquid tank;

[0054] 2) Formal cycle: Under 20°C conditions, first flow the eluent in the eluent tank through the adsorption tower at a flow rate of 1.27BV / h for adsorption, and then flow the adsorption stock solution in the stock solution tank through the adsorption tower at a flow rate of 0.8BV / h for adsorption for 2400s; then flow the cleaning solution in the cleaning solution tank through the adsorption tower at a flow rate of 1.27BV / h for elution for 2000s, and discharge the eluent and store it in the eluent tank; then flow pure water through the adsorption tower at a flow rate of 1.63BV / h for desorption for 4080s, and discharge the desorption solution and store it in the desorption solution tank; finally, flow pure water through the adsorption tower at a flow rate of 1.63BV / h for cleaning for 2040s, and discharge the cleaning solution and store it in the cleaning solution tank; repeat this cycle of operations later;

[0055] The pH of the pure water used in the above elution, desorption and cleaning processes is 5-6. Adjusting the pH of the water to a weak acid can prevent the passivation of the adsorbent in the aluminum adsorption tower.

[0056] After testing, the filtrate Li obtained in step 1 + The content is 2609mg / L, Ca 2+ The content is 535mg / L, Mg 2+ The content is 30mg / L, Mn 2+ The content is 348mg / L;

[0057] Li in the produced water obtained in step 2 + The content is 2609mg / L, Ca 2+ The content is 0.84mg / L, Mg 2+ The content is 0.57mg / L, Mn 2+ The content is 0.63mg / L;

[0058] The final purified lithium-rich solution contains Li + The content is 526mg / L, Ca 2+ Content ≤0.05mg / L, Mg 2+ Content ≤0.05mg / L, Mn 2+ Content ≤0.05mg / L.

[0059] Example 3

[0060] The brine of an oil field was adsorbed and desorbed by a manganese adsorbent to obtain a highly impure lithium-rich solution, in which Li + The content is 3160mg / L, Ca 2+ The content is 2864mg / L, Mg 2+ The content is 353.3mg / L, Mn 2+ The content is 2491mg / L.

[0061] This embodiment uses the system of embodiment 1 to purify the high-doped lithium-rich solution, including the following steps:

[0062] Step 1, the high-doped lithium-rich liquid enters the reaction tank through a pipeline, a sodium hydroxide solution with a mass concentration of 25% is added into the pipeline through a sodium hydroxide dosing tank to adjust the pH to 11, and then a 25° C. sodium carbonate saturated solution is added into the reaction tank through a sodium carbonate dosing tank, the amount of sodium carbonate added is 1.002 times the amount of calcium ion substance in the high-doped lithium-rich liquid, the stirring device in the reaction tank is started, and the reaction is carried out at a stirring rate of 40r / min for 2.5h, the reaction solution is transported to a plate and frame filter press for filtration, the filter residue is discharged, and the filtrate is collected into a filtrate tank;

[0063] Step 2, the filtrate in the filtrate tank is transported to the ceramic ultrafiltration membrane unit. The pore size of the ultrafiltration membrane used is 50nm. Two water flows are generated after ultrafiltration. The concentrated water is returned to the reaction tank through the reflux pipe for recycling, and the produced water is collected in the water production tank;

[0064] Step 3, the water produced from the water production tank is adjusted to pH 6 by adding hydrochloric acid through the hydrochloric acid dosing tank, and then stored in the stock liquid tank as the adsorption stock solution, and then transported from the stock liquid tank to the adsorption tower for adsorption and desorption, and the obtained desorption liquid is the purified lithium-rich liquid; the specific process of adsorption and desorption is:

[0065] 1) Start-up cycle: Under 25°C, the adsorption stock solution in the stock solution tank flows through the adsorption tower at a flow rate of 1BV / h for 3600s; then, pure water flows through the adsorption tower at a flow rate of 1.8BV / h for elution for 2400s, and the eluent is discharged and stored in the eluent tank; then, pure water flows through the adsorption tower at a flow rate of 1.8BV / h for desorption for 4800s, and the desorption liquid is discharged and stored in the desorption liquid tank; finally, pure water flows through the adsorption tower at a flow rate of 1.8BV / h for cleaning for 2600s, and the cleaning liquid is discharged and stored in the cleaning liquid tank;

[0066] 2) Formal cycle: Under 25°C, first let the eluent in the eluent tank flow through the adsorption tower at a flow rate of 2BV / h for adsorption, and then let the adsorption stock solution in the stock solution tank flow through the adsorption tower at a flow rate of 1BV / h for adsorption for 3600s; then let the cleaning solution in the cleaning solution tank flow through the adsorption tower at a flow rate of 1.8BV / h for elution for 2400s, and the eluent is discharged and stored in the eluent tank; then let pure water flow through the adsorption tower at a flow rate of 1.8BV / h for desorption for 4800s, and the desorption solution is discharged and stored in the desorption liquid tank; finally, let pure water flow through the adsorption tower at a flow rate of 1.8BV / h for cleaning for 2600s, and the cleaning solution is discharged and stored in the cleaning liquid tank; and repeat this cycle of operations;

[0067] The pH of the pure water used in the above elution, desorption and cleaning processes is 5-6. Adjusting the pH of the water to a weak acid can prevent the passivation of the adsorbent in the aluminum adsorption tower.

[0068] After testing, the filtrate Li obtained in step 1 + The content is 3160mg / L, Ca 2+ The content is 430mg / L, Mg 2+ The content is 50mg / L, Mn 2+ The content is 374mg / L;

[0069] Li in the produced water obtained in step 2 + The content is 3160mg / L, Ca 2+ The content is 0.76mg / L, Mg 2+ The content is 0.51mg / L, Mn 2+ The content is 0.55mg / L;

[0070] The final purified lithium-rich solution contains Li + The content is 585mg / L, Ca 2+ Content ≤0.05mg / L, Mg 2+ Content ≤0.05mg / L, Mn 2+ Content ≤0.05mg / L.

[0071] The above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above descriptions. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the protection scope of the invention.

Claims

1. A method for purifying high-doped lithium-rich liquid from oilfield brine, characterized in that: The following steps are involved: Step 1, adding sodium hydroxide solution to the high-doped lithium-rich solution to adjust the pH, then adding sodium carbonate solution, stirring for reaction, and filtering through a plate and frame filter to obtain a filter residue and a filtrate; Step 2, the filtrate is subjected to ceramic ultrafiltration to obtain two water streams, namely, produced water and concentrated water. The concentrated water is returned to step 1 to participate in the stirring reaction again; Step 3, the produced water is used as the adsorption stock solution after adjusting the pH with hydrochloric acid, and is adsorbed and desorbed by an aluminum-based adsorbent to obtain a purified lithium-rich solution.

2. The method for purifying high-doped lithium-rich liquid from oilfield brine according to claim 1, characterized in that: The highly impure lithium-rich solution is a lithium chloride solution containing divalent metal ion impurities obtained by adsorbing and desorbing oilfield brine with a manganese-based adsorbent, wherein Li + The content is 2000-3500mg / L, Ca 2+ The content is 1000-4000mg / L, Mg 2+ The content is 200-500mg / L, Mn 2 + The content is 2000-2600mg / L.

3. The method for purifying high-doped lithium-rich liquid from oilfield brine according to claim 1, characterized in that: The pH of the sodium hydroxide solution is adjusted to 7.5-11.5; the sodium carbonate solution is a saturated sodium carbonate solution at 10-35° C., and the amount of sodium carbonate is 1-1.003 times the amount of calcium ion substance in the high-doped lithium-rich solution.

4. The method for purifying high-doped lithium-rich liquid from oilfield brine according to claim 1, characterized in that: The stirring rate of the stirring reaction is 20-50r / min, and the reaction time is 2-3h; Li + The content is 2000-3500mg / L, Ca 2 + The content is 375-600mg / L, Mg 2+ The content is 30-60mg / L, Mn 2+ The content is 300-390mg / L.

5. The method for purifying high-doped lithium-rich liquid from oilfield brine according to claim 1, characterized in that: In the above scheme, the pore size of the ultrafiltration membrane of the ceramic ultrafiltration is 30-60nm; the Li + The content is 2000-3500mg / L, Ca 2+ Content ≤1mg / L, Mg 2+ Content ≤1mg / L, Mn 2+ Content ≤1mg / L; Li in the purified lithium-rich solution + The content is 450-600mg / L, Ca 2+ Content ≤0.05mg / L, Mg 2+ Content ≤0.05mg / L, Mn 2+ Content ≤0.05mg / L.

6. The method for purifying high-doped lithium-rich liquid from oilfield brine according to claim 1, characterized in that: The specific process of adsorption and desorption of the aluminum-based adsorbent is as follows: 1) Start-up cycle: the adsorption stock solution is adsorbed by the aluminum adsorbent, and then the aluminum adsorbent is eluted with pure water to obtain an eluent; then desorbed with pure water to obtain a desorbed liquid; and finally washed with pure water to obtain a washing liquid; 2) Formal cycle: The eluent and the adsorption stock solution are sequentially adsorbed by the aluminum adsorbent, and then the aluminum adsorbent is firstly eluted with the cleaning solution to obtain the eluent; then it is desorbed with pure water to obtain the desorption solution; finally, it is cleaned with pure water to obtain the cleaning solution; and this cycle of operations is subsequently repeated.

7. The method for purifying high-doped lithium-rich liquid from oilfield brine according to claim 6, characterized in that: The pH of the pure water is 5-6, and the operating temperature of the adsorption, elution, desorption and cleaning processes is 10-35°C.

8. The method for purifying high-doped lithium-rich liquid from oilfield brine according to claim 6, characterized in that: The flow rate of the eluent flowing through the aluminum adsorbent is 1-2.5BV / h, and the flow rate of the adsorption stock solution flowing through the aluminum adsorbent is 0.6-1BV / h; the flow rate of the elution, desorption and cleaning process is 1-2BV / h, the elution time is 2000-2500s, the desorption time is 4080-5000s, and the cleaning time is 2040-3000s.

9. A purification system for extracting lithium from oilfield brine to obtain high-doped lithium-rich liquid using the method of claim 1, characterized in that: The system includes a chemical precipitation device, a ceramic ultrafiltration device and an adsorption and desorption device; The chemical precipitation device comprises a reaction tank, a plate-frame filter press and a filtrate tank, the high-impurity lithium-rich solution enters through the inlet pipe of the reaction tank, a stirring device is arranged in the reaction tank, the outlet of the reaction tank is connected to the inlet of the plate-frame filter press, the water outlet of the plate-frame filter press is connected to the inlet of the filtrate tank, and the outlet of the filtrate tank is connected to the ceramic ultrafiltration device; the chemical precipitation device also comprises a sodium hydroxide dosing tank and a sodium carbonate dosing tank, the sodium hydroxide dosing tank is connected to the inlet pipe of the reaction tank, and the sodium carbonate dosing tank is connected to the reaction tank; The ceramic ultrafiltration device includes an ultrafiltration membrane unit and a water production tank; the inlet of the ceramic ultrafiltration membrane unit is connected to the outlet of the filtrate tank, the concentrated water outlet of the ceramic ultrafiltration membrane unit is connected to the inlet of the reaction tank through a reflux pipe, so that the ceramic ultrafiltration concentrated water is returned to the reaction tank for recycling, the water production outlet of the ceramic ultrafiltration membrane unit is connected to the inlet of the water production tank, and the outlet of the water production tank is connected to the adsorption and desorption device.

10. The purification system for extracting lithium from oilfield brine and high-doped lithium-rich liquid according to claim 9, characterized in that: The adsorption and desorption device includes a raw liquid tank and an adsorption tower, the inlet of the raw liquid tank is connected to the outlet of the water production tank, and the outlet of the raw liquid tank is connected to the inlet of the adsorption tower; the adsorption and desorption device also includes a hydrochloric acid dosing tank, and the hydrochloric acid dosing tank is connected to the inlet pipe of the raw liquid tank; the adsorption and desorption device also includes a leaching liquid tank, a desorption liquid tank and a cleaning liquid tank, and the outlet of the aluminum-based adsorption tower is respectively connected to the leaching liquid tank, the desorption liquid tank and the cleaning liquid tank, for storing the leaching liquid, the desorption liquid and the cleaning liquid in the desorption process; the leaching liquid tank and the cleaning liquid tank are both connected to the inlet of the adsorption tower through a reflux pipe, for returning the leaching liquid and the cleaning liquid to the adsorption tower for recycling.

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