A salt lake brine lithium extraction system

Abstract

The utility model belongs to the technical field of lithium extraction from salt lakes, and specifically relates to a salt lake brine lithium extraction system, which is a continuous ion exchange method, including 30 exchange columns; the 30 exchange columns are distributed in the adsorption area, water washing area, desorption area and water washing acid area of ​​the lithium extraction system; the first exchange column to the sixteenth exchange column are located in the adsorption area, and the exchange columns in the adsorption area are connected in series in pairs to form a group, the first exchange column and the sixteenth exchange column are connected in series, and so on; the seventeenth exchange column to the twentieth exchange column are located in the water washing area, the seventeenth exchange column and the eighteenth exchange column are connected in series, the nineteenth exchange column and the twenty-first exchange column are connected in parallel; the twenty-first exchange column to the twenty-seventh exchange column adopt a bottom-in-top-out connection method and are located in the desorption area; the twenty-eighth exchange column to the thirtieth exchange column are located in the water washing acid area, and the three exchange columns are connected in series. The system provided by the utility model can give full play to the adsorption capacity and ion selectivity of the adsorbent and improve the lithium extraction yield.

Description

Technical Field

[0001] The utility model belongs to the technical field of lithium extraction from salt lakes, and in particular relates to a lithium extraction system from salt lake brine. Background Art

[0002] As the lightest metal element in nature with the lowest standard electrode potential, lithium is known as the "white oil" of the future and is the most ideal battery material. With the development of new energy power and new energy vehicles, the demand for energy storage batteries and automotive batteries has also increased rapidly, and traditional lithium ore extraction can no longer meet market demand. However, lithium in nature also exists in large quantities in salt lake brine, and its reserves account for about 61% of the total lithium resources. How to efficiently extract lithium from salt lakes has become a problem that domestic and foreign experts are committed to solving.

[0003] Salt lake brine generally contains Li + 、Na + , K + , Ca 2+ Mg 2+ , B 3+ 、SO4 2- , Cl - 、CO3 2- Plasma, the existing processes for extracting lithium from salt lakes mainly include precipitation, adsorption, extraction, membrane separation and a combination of multiple methods. In view of the low lithium concentration and high magnesium-lithium and sodium-lithium ratios in my country's salt lake brine, the adsorption method is more suitable. The industrial application devices of the adsorption method mainly include fixed bed, moving bed and continuous moving bed types. Among them, the continuous ion exchange device (continuous moving bed type) has been successfully applied to salt lakes such as Mamicuo, Zabuye in Tibet and Dachaidan in Qinghai.

[0004] The continuous ion exchange device is used to extract lithium by dividing the ion exchange column (usually 20-30 ion exchange columns filled with adsorbent) into different functional areas, mainly including adsorption area, desorption area, water washing area, water washing acid area, etc. The general step time is 10 minutes, and each step rotates an ion exchange column in the same direction. Each ion exchange column undergoes a complete adsorption, water washing, desorption and water washing acid cycle.

[0005] However, the current method of extracting lithium from salt lakes using a continuous ion exchange device has problems such as not being able to fully utilize the adsorption capacity of the adsorbent and having low ion selectivity for brine, resulting in the inability to efficiently and stably extract lithium from salt lake brine. Utility Model Content

[0006] In view of this, the purpose of the utility model is to provide a salt lake brine lithium extraction system, which can give full play to the adsorption capacity and ion selectivity of the adsorbent and improve the lithium extraction yield.

[0007] The utility model provides a salt lake brine lithium extraction system, which is a continuous ion exchange method, including 30 exchange columns and a matching exchange column driving mechanism; each of the exchange columns is filled with an adsorbent, and the 30 exchange columns are distributed in the adsorption area, water washing area, desorption area and water washing acid area of ​​the lithium extraction system; the exchange column driving mechanism drives all the exchange columns to rotate synchronously counterclockwise when the system is running, and each step rotates one exchange column position counterclockwise, and each exchange column completely rotates through the adsorption area, water washing area, desorption area and water washing acid area in sequence;

[0008] The first exchange column that rotates into the adsorption zone is taken as the first exchange column, and the 30 exchange columns are sequentially recorded as the first exchange column, the second exchange column, the third exchange column, the fourth exchange column, the fifth exchange column, the sixth exchange column, the seventh exchange column, the eighth exchange column, the ninth exchange column, the tenth exchange column, the eleventh exchange column, the twelfth exchange column, the thirteenth exchange column, the fourteenth exchange column, the fifteenth exchange column, the sixteenth exchange column, the seventeenth exchange column, the eighteenth exchange column, the nineteenth exchange column, the twentieth exchange column, the twenty-first exchange column, the twenty-second exchange column, the twenty-third exchange column, the twenty-fourth exchange column, the twenty-fifth exchange column, the twenty-sixth exchange column, the twenty-seventh exchange column, the twenty-eighth exchange column, the twenty-ninth exchange column and the thirtieth exchange column along the path direction that successively rotates through the adsorption zone, the water washing material zone, the desorption zone and the water washing acid zone;

[0009] The first to sixteenth exchange columns are located in the adsorption zone, and the exchange columns in the adsorption zone are connected in series in pairs to form one group, with a total of eight groups, wherein the first exchange column is connected in series with the sixteenth exchange column, the second exchange column is connected in series with the fifteenth exchange column, the third exchange column is connected in series with the fourteenth exchange column, the fourth exchange column is connected in series with the thirteenth exchange column, the fifth exchange column is connected in series with the twelfth exchange column, the sixth exchange column is connected in series with the eleventh exchange column, the seventh exchange column is connected in series with the tenth exchange column, and the eighth exchange column is connected in series with the ninth exchange column;

[0010] The seventeenth to twentieth exchange columns are located in the water-washing material zone, wherein the seventeenth exchange column and the eighteenth exchange column are connected in series, and the nineteenth exchange column and the twentieth exchange column are connected in parallel;

[0011] The twenty-first to twenty-seventh exchange columns are connected in a bottom-in-top-out manner and are located in the desorption zone;

[0012] The 28th to 30th exchange columns are located in the water-washing acid zone, and the three exchange columns are connected in series;

[0013] The water washing material area is equipped with a leaching liquid tank; the desorption area is equipped with a desorption tank; and the water washing acid area is equipped with a water washing tank.

[0014] Preferably, the adsorption zone is equipped with a pipeline for transporting the tail brine after passing through the adsorbent to the salt lake.

[0015] Preferably, when the system is running, the eluent produced after eluting the seventeenth exchange column flows out of the lithium extraction system, and the eluent produced after eluting the nineteenth exchange column and the twentieth exchange column flows back to the eluent tank.

[0016] Preferably, the water washing area is also equipped with a pipeline for conveying the eluent produced by eluting the adsorbent to the salt lake.

[0017] Preferably, the desorption zone is also equipped with a pH monitoring device for monitoring the pH value of the desorption liquid and an acid liquid tank for adjusting the pH value of the desorption liquid.

[0018] Preferably, the desorption zone is also equipped with a qualified liquid tank for storing desorption qualified liquid.

[0019] Preferably, when the system is running, the liquid after desorption from the twenty-first exchange column flows into the eluent tank, the liquid after desorption from the twenty-second exchange column flows into the qualified liquid tank, and the desorbed liquid after desorption from the twenty-third to twenty-seventh exchange columns flows back to the desorption tank.

[0020] Preferably, the twenty-third to twenty-seventh exchange columns are connected in parallel.

[0021] Preferably, when the system is running, the cleaning liquid generated by the exchange column in the water-wash acid zone flows into the desorption tank.

[0022] Compared with the prior art, the utility model provides a salt lake brine lithium extraction system, which is a continuous ion exchange method, including 30 exchange columns, each of which is filled with adsorbent; the 30 exchange columns are distributed in the adsorption zone, water washing zone, desorption zone and water washing acid zone of the lithium extraction system. When the system is running, each step rotates the exchange column counterclockwise once, and each of the exchange columns completely rotates through the adsorption zone, water washing zone, desorption zone and water washing acid zone in sequence; the first exchange column that rotates into the adsorption zone is used as the first exchange column, and the 30 exchange columns rotate along the adsorption zone, water washing zone, desorption zone and water washing acid zone in sequence. The directions of the paths of the water washing material zone, the desorption zone and the water washing acid zone are recorded as the first exchange column, the second exchange column, the third exchange column, the fourth exchange column, the fifth exchange column, the sixth exchange column, the seventh exchange column, the eighth exchange column, the ninth exchange column, the tenth exchange column, the eleventh exchange column, the twelfth exchange column, the thirteenth exchange column, the fourteenth exchange column, the fifteenth exchange column, the sixteenth exchange column, the seventeenth exchange column, the eighteenth exchange column, the nineteenth exchange column, the twentieth exchange column, the twenty-first exchange column, the twenty-second exchange column, the twenty-third exchange column, the twenty-fourth exchange column, the twenty-fifth exchange column, the twenty-fifth exchange column, the twenty-third ... The twenty-sixth exchange column, the twenty-seventh exchange column, the twenty-eighth exchange column, the twenty-ninth exchange column and the thirtieth exchange column; the first to sixteenth exchange columns are located in the adsorption zone, and the exchange columns in the adsorption zone are connected in series in pairs to form a group, for a total of eight groups, wherein the first exchange column is connected in series with the sixteenth exchange column, the second exchange column is connected in series with the fifteenth exchange column, the third exchange column is connected in series with the fourteenth exchange column, the fourth exchange column is connected in series with the thirteenth exchange column, the fifth exchange column is connected in series with the twelfth exchange column, the sixth exchange column is connected in series with the eleventh exchange column, the seventh exchange column is connected in series with the eleventh exchange column, and the tenth exchange column are connected in series, the eighth exchange column and the ninth exchange column are connected in series; the seventeenth to twentieth exchange columns are located in the water washing material area, wherein the seventeenth exchange column and the eighteenth exchange column are connected in series, and the nineteenth exchange column and the twentieth exchange column are connected in parallel; the twenty-first to twenty-seventh exchange columns are connected in a bottom-in-top-out manner and are located in the desorption area; the twenty-eighth to thirtieth exchange columns are located in the water washing acid area, and the three exchange columns are connected in series; the water washing material area is equipped with a leaching liquid tank; the desorption area is equipped with a desorption tank; the water washing acid area is equipped with a water washing tank. The lithium extraction system provided by the utility model adopts a continuous ion exchange column filled with an adsorbent to adsorb salt lake lithium, and then replaces the lithium in the adsorbent with hydrogen ions in an acid solution, thereby selectively extracting the lithium in the salt lake; wherein, the water washing material zone adopts a nineteenth exchange column and a twentieth exchange column in parallel, which can increase the elution flow without increasing the water consumption, thereby better flushing the brine, reducing the content of impurity ions in the qualified liquid, and improving the ion selectivity; the exchange column in the desorption zone adopts a bottom-in and top-out method, which can avoid desorption dead corners, fully desorb, and thus improve the adsorption capacity of the adsorbent.In addition, some of the exchange columns in the desorption zone are preferably connected in parallel, which can increase the flow rate of the desorption liquid without increasing the water consumption, fully desorb, thereby increasing the adsorption capacity and increasing the lithium production. In addition, when the system is running, combined with the large flow rate of the exchange column in the desorption zone, the desorption zone preferably uses a low-concentration acid desorption with a pH value of 1.0 to 1.3, that is, the hydrogen ion concentration is 0.05 to 0.1 mol / L, to ensure that the acid concentration is reduced on the basis of complete desorption, and the erosion of the adsorbent particle skeleton by each desorption acid solution is reduced, thereby extending the service life; combined with the acid solubility of the desorption liquid and the flow rate of the exchange column in the desorption zone, maintaining a relatively low temperature can already desorb the lithium in the adsorbent well, so the temperature of the desorption zone is preferably set to between 10 and 15 ° C, and the low temperature can well avoid damaging the adsorbent structure, thereby further extending the service life of the adsorbent. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the utility model 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 in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 It is a flow chart of a salt lake brine lithium extraction system provided in an embodiment of the utility model.

[0025] The markings in the accompanying drawings are as follows: 1 is the first exchange column, 2 is the second exchange column, 3 is the third exchange column, 4 is the fourth exchange column, 5 is the fifth exchange column, 6 is the sixth exchange column, 7 is the seventh exchange column, 8 is the eighth exchange column, 9 is the ninth exchange column, 10 is the tenth exchange column, 11 is the eleventh exchange column, 12 is the twelfth exchange column, 13 is the thirteenth exchange column, 14 is the fourteenth exchange column, 15 is the fifteenth exchange column, 16 is the sixteenth exchange column, 17 is the seventeenth exchange column, 18 is the eighteenth exchange column, 19 is the nineteenth exchange column, 20 is the twentieth exchange column, 21 is the twenty-first exchange column, 22 is the twenty-second exchange column, 23 is the twenty-third exchange column, 24 is the twenty-fourth exchange column, 25 is the twenty-fifth exchange column, 26 is the twenty-sixth exchange column, 27 is the twenty-seventh exchange column, 28 is the twenty-eighth exchange column, 29 is the twenty-ninth exchange column, and 30 is the thirtieth exchange column. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] The utility model provides a salt lake brine lithium extraction system, such as Figure 1 As shown, it is a continuous ion exchange method, including 30 exchange columns and a matching exchange column driving mechanism; each of the exchange columns is filled with adsorbent, and the 30 exchange columns are distributed in the adsorption zone, water washing zone, desorption zone and water washing acid zone of the lithium extraction system; the exchange column driving mechanism drives all the exchange columns to rotate synchronously counterclockwise when the system is running, and each step rotates one exchange column position counterclockwise; each exchange column completely rotates through the adsorption zone, water washing zone, desorption zone and water washing acid zone in sequence, which is a complete adsorption-desorption lithium extraction cycle, and qualified liquid is obtained by desorbing the adsorbent from the desorption zone;

[0028] The first exchange column that rotates into the adsorption zone is taken as the first exchange column 1, and the 30 exchange columns are sequentially recorded as the first exchange column 1, the second exchange column 2, the third exchange column 3, the fourth exchange column 4, the fifth exchange column 5, the sixth exchange column 6, the seventh exchange column 7, the eighth exchange column 8, the ninth exchange column 9, the tenth exchange column 10, the eleventh exchange column 11, the twelfth exchange column 12, the thirteenth exchange column 13, the fourteenth exchange column 14, the fifteenth exchange column 15, the sixteenth exchange column 16, the seventeenth exchange column 17, the eighteenth exchange column 18, the nineteenth exchange column 19, the twentieth exchange column 20, the twenty-first exchange column 21, the twenty-second exchange column 22, the twenty-third exchange column 23, the twenty-fourth exchange column 24, the twenty-fifth exchange column 25, the twenty-sixth exchange column 26, the twenty-seventh exchange column 27, the twenty-eighth exchange column 28, the twenty-ninth exchange column 29 and the thirtieth exchange column 30 along the path direction that successively rotates through the adsorption zone, the water washing material zone, the desorption zone and the water washing acid zone;

[0029] The first exchange column 1 to the sixteenth exchange column 16 are located in the adsorption zone, and the exchange columns in the adsorption zone are connected in series in pairs to form a group, with a total of 8 groups, wherein the first exchange column 1 and the sixteenth exchange column 16 are connected in series, the second exchange column 2 and the fifteenth exchange column 15 are connected in series, the third exchange column 3 and the fourteenth exchange column 14 are connected in series, the fourth exchange column 4 and the thirteenth exchange column 13 are connected in series, the fifth exchange column 5 and the twelfth exchange column 12 are connected in series, the sixth exchange column 6 and the eleventh exchange column 11 are connected in series, the seventh exchange column 7 and the tenth exchange column 10 are connected in series, and the eighth exchange column 8 and the ninth exchange column 9 are connected in series;

[0030] The seventeenth exchange column 17 to the twentieth exchange column 20 are located in the water-washing material area, wherein the seventeenth exchange column 17 and the eighteenth exchange column 18 are connected in series, and the nineteenth exchange column 19 and the twentieth exchange column 20 are connected in parallel;

[0031] The twenty-first exchange column 21 to the twenty-seventh exchange column 27 are connected in a bottom-in and top-out manner and are located in the desorption zone;

[0032] The twenty-eighth exchange column 28 to the thirtieth exchange column 30 are located in the water-wash acid zone, and three exchange columns are connected in series.

[0033] In the lithium extraction system provided by the utility model, the adsorption area is preferably equipped with a pipeline for transporting the tail brine after the adsorbent is passed to the salt lake; the water washing area is equipped with a leaching liquid tank, and preferably is also equipped with a pipeline for transporting the leaching liquid generated by eluting the adsorbent to the salt lake; the desorption area is equipped with a desorption tank, and preferably is also equipped with a pH monitoring device for monitoring the pH value of the desorption liquid and an acid tank for adjusting the pH value of the desorption liquid, and preferably is also equipped with a qualified liquid tank for storing qualified desorption liquid; the water washing acid area is equipped with a water washing tank.

[0034] In the lithium extraction system provided by the utility model, the elution liquid tank is filled with clean water for eluting the adsorbent in the exchange column of the water washing material zone, which is mainly pure water and a part of the desorption liquid desorbed from the desorption zone; the desorption tank is filled with acid washing liquid (desorption liquid) for pickling the adsorbent in the exchange column of the desorption zone, and the acid tank is preferably filled with an acid solution with a hydrogen ion concentration of 4 to 8 mol / L, which flows into the desorption tank through a pipeline to adjust the pH value of the acid washing liquid in the desorption tank; the water washing tank is filled with pure water for flushing the adsorbent in the exchange column of the water washing acid zone.

[0035] In the lithium extraction system provided by the utility model, when the system is in operation, the adsorbent in the exchange column of the adsorption zone adsorbs the lithium in the salt lake brine and transfers the lithium in the brine to the adsorbent; then the exchange column moves to the water washing zone, and the brine remaining in the adsorbent is rinsed with the elution liquid; the exchange column after elution moves to the desorption zone, and the lithium in the adsorbent is desorbed with the desorption liquid in the desorption tank, that is, the lithium in the adsorbent is replaced with hydrogen ions; after desorption, it moves to the water washing acid zone, and the desorption liquid remaining in the adsorbent is washed with pure water to prevent the desorption liquid from entering the adsorption zone and affecting the adsorbent capacity.

[0036] In the lithium extraction system provided by the utility model, when the system is running, in the water washing material area, the eluent produced after eluting the eighteenth exchange column 18 flows into the seventeenth exchange column 17, and the eluent produced after eluting the seventeenth exchange column 17 preferably flows out of the lithium extraction system and is transported to the salt lake; the eluent produced after eluting the nineteenth exchange column 19 and the twentieth exchange column 20 preferably flows back to the eluent tank.

[0037] In the lithium extraction system provided by the utility model, when the system is running, in the desorption zone, the liquid after desorption from the twenty-first exchange column 21 preferably flows into the eluent tank; the liquid after desorption from the twenty-second exchange column 22 preferably flows into the qualified liquid tank; the twenty-third exchange columns 23 to the twenty-seventh exchange columns 27 are preferably connected in parallel, and the desorbed liquid after desorption from the twenty-third exchange columns 23 to the twenty-seventh exchange columns 27 preferably flows back to the desorption tank.

[0038] In the lithium extraction system provided by the utility model, when the system is running, in the water washing acid zone, the cleaning liquid generated after the thirtieth exchange column 30 is cleaned flows into the twenty-ninth exchange column 29, the cleaning liquid generated after the twenty-ninth exchange column 29 is cleaned flows into the twenty-eighth exchange column 28, and the cleaning liquid generated after the twenty-eighth exchange column 28 is cleaned preferably flows into the desorption tank; that is, the cleaning liquid generated by the exchange columns in the water washing acid zone preferably flows into the desorption tank.

[0039] In the lithium extraction system provided by the utility model, when the system is running, the flow rate of the exchange column in the adsorption zone is preferably 3-6BV / h, specifically 3BV / h, 3.5BV / h, 4BV / h, 4.5BV / h, 5BV / h, 5.5BV / h or 6BV / h; the adsorption temperature of the exchange column in the adsorption zone is preferably 15-20°C, specifically 15°C, 16°C, 17°C, 18°C, 19°C or 20°C.

[0040] In the lithium extraction system provided by the utility model, when the system is running, the eluent flow rates of the seventeenth exchange column 17 and the eighteenth exchange column 18 in the water washing material zone are preferably independently 6-12 BV / h, specifically 6 BV / h, 7 BV / h, 8 BV / h, 9 BV / h, 10 BV / h, 11 BV / h or 12 BV / h; the eluent flow rates of the nineteenth exchange column 19 and the twentieth exchange column 20 are preferably independently 12-20 BV / h, specifically 12 BV / h, 13 BV / h, 14 BV / h, 15 BV / h, 16 BV / h, 17 BV / h, 18 BV / h, 19 BV / h or 20 BV / h; the elution temperature of the exchange columns in the water washing material zone is preferably ambient temperature.

[0041] In the lithium extraction system provided by the utility model, when the system is running, the pH value of the desorption liquid in the desorption zone is preferably 1.0-1.3, specifically 1.0, 1.1, 1.2 or 1.3; the desorption liquid flow rate of the twenty-first exchange column 21 is preferably 3-8 BV / h, specifically 3 BV / h, 4 BV / h, 5 BV / h, 6 BV / h, 7 BV / h or 8 BV / h; the desorption liquid flow rate of the twenty-second exchange column 22 is preferably 4-8 BV / h, specifically 4 BV / h, 5 BV / h, 6 BV / h, 7 BV / h or 8 BV / h. / h, 6BV / h, 7BV / h or 8BV / h; the desorption liquid flow rates of the twenty-third exchange column 23 to the twenty-seventh exchange column 27 are independently preferably 8-15BV / h, specifically 8BV / h, 9BV / h, 10BV / h, 11BV / h, 12BV / h, 13BV / h, 14BV / h or 15BV / h; the desorption temperature of the exchange column in the desorption zone is preferably 10-15°C, specifically 10°C, 11°C, 12°C, 13°C, 14°C or 15°C.

[0042] In the lithium extraction system provided by the utility model, when the system is running, the cleaning liquid flow rates of the twenty-eighth exchange column 28 to the thirtieth exchange column 30 in the water washing acid zone are independently preferably 6 to 12 BV / h, specifically 6 BV / h, 7 BV / h, 8 BV / h, 9 BV / h, 10 BV / h, 11 BV / h or 12 BV / h; the cleaning temperature of the exchange columns in the water washing acid zone is preferably ambient temperature.

[0043] In the lithium extraction system provided by the utility model, when the system is in operation, the lithium ion concentration in the obtained qualified liquid is preferably 5 to 10 times the concentration of the salt lake brine; the sodium ion concentration is preferably 1% to 5% of the concentration of the salt lake brine; the magnesium ion concentration is preferably 10% to 50% of the concentration of the salt lake brine; the potassium ion concentration is preferably 0.3% to 1% of the concentration of the salt lake brine; and the calcium ion concentration is preferably 1% to 20% of the concentration of the salt lake brine. That is, after continuous ion exchange for lithium extraction, the lithium ion concentration is preferably increased by 5 to 10 times, and other impurity ions are reduced to varying degrees.

[0044] The key technical points and advantages of the salt lake brine lithium extraction system provided by the utility model are as follows:

[0045] (1) The water washing zone adopts the mode of connecting the nineteenth exchange column 19 and the twentieth exchange column 20 in parallel, and preferably sets the washing flow rate to 10-12 BV / h, and increases the washing flow rate without increasing the water consumption, so as to better wash the brine, reduce the content of impurity ions in the qualified liquid, and improve the ion selectivity;

[0046] (2) The exchange column in the desorption zone adopts a bottom-in and top-out method, which can avoid desorption dead corners and fully desorb, thereby increasing the adsorption capacity of the adsorbent;

[0047] (3) Some of the exchange columns in the desorption zone are preferably connected in parallel, and the flow rate is preferably set to 8 to 15 BV / h. The flow rate of the desorption liquid is increased without increasing the water consumption, and the desorption is fully performed, thereby increasing the adsorption capacity and increasing the lithium production;

[0048] (4) In combination with the large flow rate of the exchange column in the desorption zone, the desorption zone preferably uses a low-concentration acid desorption with a pH value of 1.0 to 1.3 to reduce the dissolution loss of the adsorbent and extend the service life of the adsorbent;

[0049] (5) Considering the acid solubility of the desorption liquid and the exchange column flow rate in the desorption zone, the temperature in the desorption zone is preferably between 10 and 15°C to avoid damaging the adsorbent structure, thereby extending the service life of the adsorbent.

[0050] For the purpose of greater clarity, the invention is described in detail through the following embodiments.

[0051] Example 1

[0052] This embodiment provides a Figure 1 The salt lake brine lithium extraction system shown in the figure adopts a continuous ion exchange method, using the adsorbent in the exchange column to selectively adsorb lithium in the salt lake brine, and then replaces the lithium in the adsorbent with hydrogen ions in a dilute acid solution, thereby achieving the effect of selective lithium extraction; the lithium extraction system consists of 30 exchange columns and matching exchange column drive mechanisms, storage tanks and pipelines; the exchange columns are filled with titanium adsorbents, and the 30 exchange columns are divided into an adsorption zone, a water washing zone, a desorption zone and a water washing acid zone; the exchange column drive mechanism drives all exchange columns to rotate synchronously counterclockwise when the system is running, and each step rotates one exchange column position counterclockwise; when the system is running, each of the exchange columns completely rotates through the adsorption zone, water washing zone, desorption zone and water washing acid zone in sequence, which is a complete adsorption-desorption lithium extraction cycle, and qualified liquid is obtained by desorbing the adsorbent from the desorption zone. Specific instructions are as follows:

[0053] (1) The adsorption zone is provided with 16 exchange columns, namely the first exchange column 1 to the sixteenth exchange column 16, which are connected in a 2-in-8-in-parallel manner, that is, the first exchange column 1 and the sixteenth exchange column 16 are connected in series, the second exchange column 2 and the fifteenth exchange column 15 are connected in series, and so on; the water washing zone is provided with 4 exchange columns, namely the seventeenth exchange column 17 to the twentieth exchange column 20, the seventeenth exchange column 17 and the eighteenth exchange column 18 are connected in series, and the nineteenth exchange column 19 and the twentieth exchange column 20 are connected in parallel; the desorption zone is provided with 7 exchange columns, namely the twenty-first exchange column 21 to the twenty-seventh exchange column 27; the water washing acid zone is provided with 3 exchange columns in series, namely the twenty-eighth exchange column 28 to the thirtieth exchange column 30.

[0054] (2) The salt lake brine is transported to the top of the ninth exchange column 9 to the sixteenth exchange column 16 through a pipeline, flows through the ninth exchange column 9 to the sixteenth exchange column 16 in parallel, and then flows into the bottom of the first exchange column 1 to the eighth exchange column 8 connected in series respectively, and finally the tail brine flowing out from the top of the first exchange column 1 to the eighth exchange column 8 is transported back to the salt lake. The flow rate of the brine is set to 4 BV / h.

[0055] (3) Pure water is injected into the water washing tank, and then 10 to 20 L of pure water is maintained in the water washing tank; the pure water in the water washing tank is transported to the top of the 30th exchange column 30, and the outflowing cleaning liquid flows into the top of the 28th exchange column 28 and the 29th exchange column 29 in turn, and the cleaned liquid flows into the desorption tank; the flow rate of pure water in the 30th exchange column 30 is 8.5 BV / h.

[0056] (4) The acid solution in the acid tank is added to the desorption tank to ensure that the pH value in the desorption tank is 1.0-1.3, and the pH value of the desorption liquid in the desorption tank is monitored by a pH meter; the desorption liquid flows in from the bottom of the twenty-third exchange column 23 to the twenty-seventh exchange column 27 connected in parallel, and the desorbed liquid flows back to the desorption tank, and the flow rate is set to 15 BV / h; the desorption liquid flows in from the bottom of the twenty-first exchange column 21, and the desorbed liquid flows into the eluent tank, and the flow rate is set to 4.5 BV / h; the desorption liquid flows in from the bottom of the twenty-second exchange column 22, and the qualified liquid flows out from the top and is transported to the next process for further purification, and the flow rate is set to 5 BV / h.

[0057] (5) Pure water is added to the eluent tank to ensure that there is 10 to 20 L of eluent in the tank; the eluent flows in from the top of the nineteenth exchange column 19 and the top of the twentieth exchange column 20 respectively, and flows back to the eluent tank after elution, and the flow rate is set to 16 BV / h; the eluent flows in from the top of the eighteenth exchange column 18, and the liquid after elution flows in from the top of the seventeenth exchange column 17, and the eluent after elution is transported to the salt lake, and the flow rate is set to 8 BV / h.

[0058] (6) The temperature of the twenty-first exchange column 21 to the twenty-seventh exchange column 27 in the desorption zone is controlled to be 13° C., and the temperature of the exchange columns in the remaining areas is controlled according to the ambient temperature.

[0059] (7) The step is set to 10 minutes. After each step is completed, the adsorbent moves as a whole to one exchange column position, that is, the adsorbent of the sixteenth exchange column 16 moves to the position of the seventeenth exchange column 17, the adsorbent of the twentieth exchange column 20 moves to the position of the twenty-first exchange column 21, the adsorbent of the twenty-seventh exchange column 27 moves to the position of the twenty-eighth exchange column 28, and so on.

[0060] In a pilot test at a salt lake in Tibet, the above system was used to carry out a pilot test of lithium extraction. The test results are shown in Table 1.

[0061] Table 1 Lithium extraction pilot test results

[0062]

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A salt lake brine lithium extraction system, characterized in that: It is a continuous ion exchange method, including 30 exchange columns and a matching exchange column driving mechanism; each of the exchange columns is filled with adsorbent, and the 30 exchange columns are distributed in the adsorption area, water washing area, desorption area and water washing acid area of ​​the lithium extraction system; the exchange column driving mechanism drives all the exchange columns to rotate synchronously counterclockwise when the system is running, and each step rotates one exchange column position counterclockwise, and each exchange column completely rotates through the adsorption area, water washing area, desorption area and water washing acid area in sequence; The first exchange column that rotates into the adsorption zone is taken as the first exchange column, and the 30 exchange columns are sequentially recorded as the first exchange column, the second exchange column, the third exchange column, the fourth exchange column, the fifth exchange column, the sixth exchange column, the seventh exchange column, the eighth exchange column, the ninth exchange column, the tenth exchange column, the eleventh exchange column, the twelfth exchange column, the thirteenth exchange column, the fourteenth exchange column, the fifteenth exchange column, the sixteenth exchange column, the seventeenth exchange column, the eighteenth exchange column, the nineteenth exchange column, the twentieth exchange column, the twenty-first exchange column, the twenty-second exchange column, the twenty-third exchange column, the twenty-fourth exchange column, the twenty-fifth exchange column, the twenty-sixth exchange column, the twenty-seventh exchange column, the twenty-eighth exchange column, the twenty-ninth exchange column and the thirtieth exchange column along the path direction that successively rotates through the adsorption zone, the water washing material zone, the desorption zone and the water washing acid zone; The first to sixteenth exchange columns are located in the adsorption zone, and the exchange columns in the adsorption zone are connected in series in pairs to form one group, with a total of eight groups, wherein the first exchange column is connected in series with the sixteenth exchange column, the second exchange column is connected in series with the fifteenth exchange column, the third exchange column is connected in series with the fourteenth exchange column, the fourth exchange column is connected in series with the thirteenth exchange column, the fifth exchange column is connected in series with the twelfth exchange column, the sixth exchange column is connected in series with the eleventh exchange column, the seventh exchange column is connected in series with the tenth exchange column, and the eighth exchange column is connected in series with the ninth exchange column; The seventeenth to twentieth exchange columns are located in the water-washing material zone, wherein the seventeenth exchange column and the eighteenth exchange column are connected in series, and the nineteenth exchange column and the twentieth exchange column are connected in parallel; The twenty-first to twenty-seventh exchange columns are connected in a bottom-in-top-out manner and are located in the desorption zone; The 28th to 30th exchange columns are located in the water-washing acid zone, and the three exchange columns are connected in series; The water washing material area is equipped with a leaching liquid tank; the desorption area is equipped with a desorption tank; and the water washing acid area is equipped with a water washing tank.

2. The salt lake brine lithium extraction system according to claim 1, characterized in that: The adsorption area is equipped with a pipeline for transporting the tail brine after passing through the adsorbent to the salt lake.

3. The salt lake brine lithium extraction system according to claim 1, characterized in that: When the system is running, the eluent generated after eluting the seventeenth exchange column flows out of the lithium extraction system, and the eluent generated after eluting the nineteenth exchange column and the twentieth exchange column flows back to the eluent tank.

4. The salt lake brine lithium extraction system according to claim 1, characterized in that: The water washing material area is also equipped with a pipeline for conveying the eluent generated by the elution adsorbent to the salt lake.

5. The salt lake brine lithium extraction system according to claim 1, characterized in that: The desorption zone is also equipped with a pH monitoring device for monitoring the pH value of the desorption liquid and an acid liquid tank for adjusting the pH value of the desorption liquid.

6. The salt lake brine lithium extraction system according to claim 1, characterized in that: The desorption zone is also equipped with a qualified liquid tank for storing desorption qualified liquid.

7. The salt lake brine lithium extraction system according to claim 6, characterized in that: When the system is running, the liquid after desorption from the twenty-first exchange column flows into the eluent tank, the liquid after desorption from the twenty-second exchange column flows into the qualified liquid tank, and the desorbed liquid after desorption from the twenty-third exchange column to the twenty-seventh exchange column flows back to the desorption tank.

8. The salt lake brine lithium extraction system according to claim 7, characterized in that: The twenty-third to twenty-seventh exchange columns are connected in parallel.

9. The salt lake brine lithium extraction system according to claim 1, characterized in that: When the system is running, the cleaning liquid produced by the exchange column in the water-washing acid zone flows into the desorption tank.

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