Method for extracting potassium by adsorption of salt lake raw brine
By combining modified zeolite adsorbent with lithium precipitation mother liquor, the problem of insufficient selective adsorption capacity of potassium ions in high magnesium-to-lithium ratio salt lake brine is solved, realizing efficient and low-cost potassium ion extraction and resource recycling, which is applicable to the field of salt lake brine resource processing.
Patent Information
- Application Number
- CN202610084416.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-22
- Publication Date
- 2026-05-26
AI Technical Summary
Existing adsorbents exhibit reduced selective adsorption capacity when treating raw brine from salt lakes with high magnesium-to-lithium ratios and complex compositions, resulting in low potassium extraction purity, high costs for subsequent desorption and purification, and long production cycles and low resource utilization rates with traditional methods.
Zeolite adsorbent modified with lithium precipitation mother liquor, using lithium precipitation mother liquor as desorbent, and through an integrated method of pretreatment, adsorption, desorption and posttreatment, the adsorption capacity and selectivity of potassium ions are improved, achieving efficient and selective enrichment of potassium ions.
It has achieved efficient extraction of potassium ions from complex salt lake brine, improved adsorption capacity and selectivity, shortened the production cycle, reduced costs, and enabled resource recycling and continuous production throughout the year.
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Figure CN122081676A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of salt lake brine resource processing technology, specifically to a method for potassium extraction by adsorption of salt lake brine. Background Technology
[0002] Currently, the mainstream processes for extracting potassium salts from salt lake brines include salt pan evaporation, flotation, and cold crystallization. However, these traditional methods generally have the following limitations: they are heavily dependent on natural climate (such as evaporation rate and temperature), have long production cycles, and their production capacity is limited by the seasons; they have stringent requirements for brine composition, typically requiring the brine to reach a certain potassium ion concentration (such as carnallite point), and the magnesium-to-lithium ratio cannot be too high; they have low resource utilization rates, limited potassium yields, and difficulty in effectively separating and recovering coexisting valuable elements such as lithium, boron, and magnesium; furthermore, salt pans occupy large amounts of land. To overcome these shortcomings, adsorption methods have received widespread attention as a novel potassium extraction technology. Currently, commonly used potassium extraction adsorbents (such as natural zeolite, organic ion exchange resins, and inorganic composite materials) generally suffer from low adsorption capacity and poor selectivity (especially for Na+). + Mg² + Existing adsorbents suffer from problems such as low separation coefficient, high dissolution rate, and short cycle life. For salt lake brine with high magnesium-to-lithium ratio and complex composition, the selective adsorption capacity of existing adsorbents decreases sharply, resulting in low potassium extraction purity and high subsequent desorption and purification costs. Summary of the Invention
[0003] The purpose of this invention is to overcome the problems of existing technologies where the selective adsorption capacity of adsorbents drastically decreases for salt lake brine with high magnesium-to-lithium ratios and complex compositions, leading to low potassium purity and high costs for subsequent desorption and purification. This invention provides a method for potassium extraction using salt lake brine adsorption. This technical solution employs lithium precipitation mother liquor to modify zeolite adsorbents and uses the lithium precipitation mother liquor as a desorbent, thereby improving the adsorption capacity and selectivity of potassium ions while simultaneously realizing the resource utilization of waste liquid. It provides a method integrating pretreatment, adsorption, desorption, and post-treatment, efficiently and selectively enriching potassium ions from complex salt lake brine. This method features a short process flow, low cost, and can be continuously produced year-round, achieving high-yield potassium extraction and continuous production. This method can directly and efficiently process complex salt lake brine, exhibiting high selectivity and high adsorption capacity while enabling resource recycling.
[0004] To achieve the above objectives, the present invention provides a method for potassium extraction by adsorption using raw brine from a salt lake, the method comprising the following steps: (1) The zeolite adsorbent is crushed, washed and dried to obtain a pretreated zeolite adsorbent. The pretreated zeolite adsorbent is then modified with the lithium precipitation mother liquor generated during the lithium extraction process in the salt lake to obtain a modified zeolite adsorbent. (2) The modified zeolite adsorbent is packed into an adsorption column, and the original brine of the salt lake is passed through the adsorption column for potassium ion adsorption; (3) Use the lithium precipitation mother liquor generated during the lithium extraction process in the salt lake as a desorbent to desorb the adsorption column that has undergone potassium ion adsorption in step (2) to obtain intermediate potassium-rich solution. (4) After desorption in step (3), the adsorption column after desorption is rinsed and potassium ion adsorption is performed in step (2). (5) First, use the intermediate potassium-rich liquid from the 1st BV to the 4th BV obtained in step (3) as a desorbent to desorb the adsorption column that has undergone potassium ion adsorption in step (4), and then use the lithium precipitation mother liquor generated during the lithium extraction process in the salt lake as a desorbent to desorb the final potassium-rich liquid product.
[0005] Preferably, in step (1), the zeolite adsorbent is pulverized to 20-60 mesh.
[0006] Preferably, the zeolite adsorbent is natural clinoptilolite and / or synthetic zeolite.
[0007] Preferably, in step (1), in the lithium precipitation mother liquor, Na + The content is 10-30g / L, K + The content of lithium is 0.1-0.6 g / L; the pH value of the lithium precipitation mother liquor is 12-14.
[0008] Preferably, in step (1), the modification conditions include: a temperature of 70-90°C and a time of 1-3 hours.
[0009] Preferably, in step (1), the mass ratio of the zeolite adsorbent to the lithium precipitation mother liquor is 1:(2-4).
[0010] Preferably, in the original brine of the salt lake, the concentration of potassium ions is 6-10 g / L, the concentration of magnesium ions is 20-30 g / L, the concentration of calcium ions is 1-3 g / L, the concentration of sodium ions is 60-80 g / L, and the concentration of chloride ions is 170-190 g / L.
[0011] Preferably, the method further includes filtering and adjusting the temperature of the salt lake brine before step (2).
[0012] Preferably, in step (2), the feed flow rate of the salt lake brine is 2-6 BV / h.
[0013] Preferably, in step (3), in the lithium precipitation mother liquor, Na + The content is 10-30g / L, K +The content of lithium is 0.1-0.6 g / L; the pH value of the lithium precipitation mother liquor is 12-14.
[0014] Preferably, in step (3), the temperature of the lithium precipitation mother liquor is 70-90℃ and the flow rate is 2-4 BV / h.
[0015] Compared with the prior art, the present invention has the following technical effects: (1) The method described in this invention shortens the traditional evaporation cycle of several months to several hours, enabling continuous and stable production throughout the year and significantly improving capacity and efficiency; (2) The present invention improves the adsorption capacity and selectivity of potassium ions in complex salt lake brine (especially brine with high magnesium-to-lithium ratio) by modifying the zeolite adsorbent, thereby improving the potassium purity at the source. (3) This invention creatively uses lithium precipitation mother liquor as both a modifier and a desorbent, realizing "waste treatment"; it reduces reagent costs and solves the problem of lithium precipitation mother liquor treatment, realizing the internal circulation of lithium and potassium resource development, which is in line with the concept of green chemical industry. (4) Under preferred conditions, by using specific adsorption and desorption flow rates and temperatures and other key parameters, the lowest point of comprehensive production cost was found while ensuring high potassium yield, and the prospects for industrialization are broad. (5) Long adsorbent life: The modified zeolite has a stable structure and its performance decay rate is extremely low (<5%) after multiple cycles of adsorption and desorption. It has a long service life and low operating cost. Attached Figure Description
[0016] Figure 1 This is a process flow diagram of the method for potassium extraction by adsorption using raw brine from salt lakes as described in this invention; Figure 2 This is a comparison chart showing the effect of different desorption flow rates on the potassium ion concentration (enrichment effect) in potassium-rich solutions. Detailed Implementation
[0017] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.
[0018] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0019] like Figure 1As shown, the method for potassium extraction using brine adsorption in salt lakes according to the present invention includes the following steps: (1) The zeolite adsorbent is crushed, washed and dried to obtain a pretreated zeolite adsorbent. The pretreated zeolite adsorbent is then modified with the lithium precipitation mother liquor generated during the lithium extraction process in the salt lake to obtain a modified zeolite adsorbent. (2) The modified zeolite adsorbent is packed into an adsorption column, and the original brine of the salt lake is passed through the adsorption column for potassium ion adsorption; (3) Use the lithium precipitation mother liquor generated during the lithium extraction process in the salt lake as a desorbent to desorb the adsorption column that has undergone potassium ion adsorption in step (2) to obtain intermediate potassium-rich solution. (4) After desorption in step (3), the adsorption column after desorption is rinsed and potassium ion adsorption is performed in step (2). (5) First, use the intermediate potassium-rich liquid from the 1st BV to the 4th BV obtained in step (3) as a desorbent to desorb the adsorption column that has undergone potassium ion adsorption in step (4), and then use the lithium precipitation mother liquor generated during the lithium extraction process in the salt lake as a desorbent to desorb the final potassium-rich liquid product.
[0020] According to the method described in this invention, the technology of modifying zeolite adsorbent with lithium mother liquor and using it as a desorbent improves adsorption capacity and selectivity, while realizing the resource utilization of waste liquid. This invention can also efficiently and selectively enrich potassium ions from complex salt lake brine, and has a short process flow, low cost, and can be continuously produced throughout the year.
[0021] In the method described in this invention, in step (1), the zeolite adsorbent is pulverized to 20-60 mesh. Using a zeolite adsorbent with a specific particle size enhances the adsorption capacity and selectivity. The zeolite adsorbent can be natural clinoptilolite and / or synthetic zeolite, preferably natural clinoptilolite. Since the zeolite adsorbent can be purchased directly with a mesh size of 20-60, there is no need for manual pulverization.
[0022] In the method described in this invention, in step (1), the drying conditions include: a temperature of 85-100℃, preferably 80-90℃; and a time of 1-3 hours, preferably 2-3 hours. The cleaning can be performed using water.
[0023] In the method described in this invention, in step (1), Na in the lithium precipitation mother liquor + The content can be 10-30 g / L, preferably 15-30 g / L; K +The content can be 0.1-0.6 g / L, preferably 0.1-0.3 g / L. The pH value of the lithium precipitation mother liquor can be 12-14, preferably 12-13. The lithium precipitation mother liquor is the mother liquor remaining after extracting lithium carbonate from salt lake brine.
[0024] In the method described in this invention, in step (1), to improve the adsorption capacity, the modification conditions include: a temperature preferably of 70-90°C, more preferably 80-90°C; and a time preferably of 1-3 hours, more preferably 2-3 hours. The modification process may involve shaking or stirring. To improve adsorption capacity and selectivity, the modification is preferably repeated 2-4 times. The modification process can be carried out intermittently in a stirred reactor or continuously in a column reactor. In some embodiments, the modification is carried out under stirring at a stirring rate of 100-200 rpm.
[0025] In the method described in this invention, in step (1), in order to improve the adsorption capacity, the mass ratio of the amount of the zeolite adsorbent to the amount of the lithium precipitation mother liquor is preferably 1:(2-4), more preferably 1:(2-3).
[0026] In the method described in this invention, the method may further include: before step (2), rinsing and drying the modified zeolite adsorbent. The drying conditions include: a temperature of 85-100℃, preferably 80-90℃; and a time of 1-3 hours, preferably 2-3 hours.
[0027] In the method described in this invention, the adsorption column can be designed as multiple columns connected in parallel or in series, enabling continuous or semi-continuous operation of the adsorption and desorption processes. In some embodiments, the adsorption column can be multiple columns connected in parallel, with one column adsorbing while another column desorbs or regenerates, achieving truly continuous production.
[0028] In the method described in this invention, the original brine from the salt lake may contain K. + Na + Ca 2+ Mg 2+ and Cl - In the raw brine of the salt lake, the concentration of potassium ions can be 6-10 g / L, preferably 6-8 g / L; the concentration of magnesium ions can be 20-30 g / L, preferably 20-25 g / L; the concentration of calcium ions can be 1-3 g / L, preferably 1-2 g / L; the concentration of sodium ions is 60-80 g / L, preferably 70-80 g / L; and the concentration of chloride ions is 170-190 g / L, preferably 170-180 g / L.
[0029] In the method described in this invention, the method may further include: before step (2), filtering and adjusting the temperature of the raw brine from the salt lake. The temperature of the raw brine from the salt lake is adjusted to 30-40°C.
[0030] In the method described in this invention, in step (2), the feed flow rate of the raw brine from the salt lake can be 2-6 BV / h, preferably 2-4 BV / h. In this paper, BV is the volume of the zeolite bed in the adsorption column.
[0031] In the method described in this invention, in step (3), Na in the lithium precipitation mother liquor + The content can be 10-30 g / L, preferably 15-30 g / L; K + The content can be 0.1-0.6 g / L, preferably 0.1-0.3 g / L. The pH value of the lithium precipitation mother liquor can be 12-14, preferably 12-13. The lithium precipitation mother liquor is the mother liquor remaining after extracting lithium carbonate from salt lake brine. In step (3), the lithium precipitation mother liquor is used as a desorbent to maximize economic and environmental benefits. In scenarios where lithium precipitation mother liquor resources are limited, sodium chloride and / or ammonium chloride can be used as the desorbent.
[0032] In the method described in this invention, in step (3), the temperature of the lithium precipitation mother liquor can be 70-90℃, preferably 80-90℃; the flow rate can be 2-4 BV / h, preferably 2-3 BV / h.
[0033] In the method described in this invention, in step (4), rinsing the desorbed adsorption column can be done by rinsing the adsorption column with fresh water or low-concentration saline. Rinsing the desorbed adsorption column restores its adsorption capacity, allowing it to be recycled more than 5 times with an adsorption capacity decrease of less than 5%.
[0034] In the method described in this invention, in step (5), the volume ratio of the intermediate potassium-rich solution to the lithium precipitation mother liquor can be 1:(1-2), preferably 1:(1.2-1.5).
[0035] In the method described in this invention, in step (5), the temperature of the intermediate potassium-rich solution can be 70-90℃, preferably 80-90℃; the flow rate can be 2-4 BV / h, preferably 2-3 BV / h.
[0036] In the method described in this invention, in step (5), the temperature of the lithium precipitation mother liquor can be 70-90℃, preferably 80-90℃; the flow rate can be 2-4 BV / h, preferably 2-3 BV / h.
[0037] In the method described in this invention, in step (5), Na in the lithium precipitation mother liquor +The content can be 10-30 g / L, preferably 15-30 g / L; K + The content can be 0.1-0.6 g / L, preferably 0.1-0.3 g / L. The pH value of the lithium precipitation mother liquor can be 12-14, preferably 12-13. The lithium precipitation mother liquor is the mother liquor remaining after extracting lithium carbonate from salt lake brine. In step (5), the lithium precipitation mother liquor is used as a desorbent to maximize economic and environmental benefits. In scenarios where lithium precipitation mother liquor resources are limited, sodium chloride and / or ammonium chloride can be used as the desorbent.
[0038] In the method described in this invention, the method may further include: evaporating, concentrating, and crystallizing the final potassium-rich liquid product obtained in step (5). The evaporation, concentration, and crystallization can be performed using methods conventionally used in the art. Various evaporation, concentration, and crystallization conditions can achieve the same desired effect.
[0039] In some embodiments, the method of the present invention is implemented in a system for potassium extraction by adsorption using raw brine from a salt lake. This system includes a raw brine pretreatment unit, an adsorption unit, a desorption unit, and a potassium-rich solution post-treatment unit. The raw brine pretreatment unit is used to filter and regulate the temperature of the raw brine. The adsorption unit includes an adsorption column filled with modified zeolite adsorbent, a flow control device, and a pressure control device. The adsorption unit is used to adsorb potassium ions from the raw brine through the adsorption column. In the adsorption unit, the flow control device is used to control the feed flow rate of the raw brine. The desorption unit includes a lithium precipitation mother liquor storage tank, a heating device, and a transfer pump, used to provide heated lithium precipitation mother liquor to the adsorption unit for desorption. The potassium-rich solution post-treatment unit is used to evaporate, concentrate, and crystallize the potassium-rich solution obtained after desorption.
[0040] In some implementations, such as Figure 1 As shown, the method for potassium extraction using brine adsorption in salt lakes according to the present invention includes the following steps: (1) The zeolite adsorbent is pulverized to 20-60 mesh, washed with water, and then dried at 85-100℃ for 1-3 hours to obtain a pretreated zeolite adsorbent. The pretreated zeolite adsorbent is then modified with lithium precipitation mother liquor generated during the lithium extraction process in salt lake by shaking or stirring at 70-90℃ for 1-3 hours, and the modification is repeated 2-4 times to obtain a modified zeolite adsorbent. The modified zeolite adsorbent is then washed with water and dried at 85-100℃ for 1-3 hours. The mass ratio of the zeolite adsorbent to the lithium precipitation mother liquor is 1:(2-4). In the lithium precipitation mother liquor, Na + The content is 10-30g / L, K + The content of lithium is 0.1-0.6 g / L; the pH value of the lithium precipitation mother liquor is 12-14; (2) The modified zeolite adsorbent is packed into an adsorption column, the salt lake brine is filtered and the temperature is adjusted to 30-40℃, and then the salt lake brine is passed through the adsorption column at a feed flow rate of 2-6 BV / h for potassium ion adsorption. In the salt lake brine, the concentration of potassium ions is 6-10 g / L, the concentration of magnesium ions is 20-30 g / L, the concentration of calcium ions is 1-3 g / L, the concentration of sodium ions is 60-80 g / L, and the concentration of chloride ions is 170-190 g / L. (3) The lithium precipitation mother liquor produced during the lithium extraction process in the salt lake is heated to 70-90℃ and used as a desorbent at a flow rate of 2-4 BV / h to desorb the adsorption column that has undergone potassium ion adsorption in step (2), thereby obtaining an intermediate potassium-rich solution. In the lithium precipitation mother liquor, Na + The content is 15-30g / L, K + The content is 0.1-0.3 g / L; the pH value of the lithium precipitation mother liquor is 12-13; (4) After desorption in step (3), the adsorption column after desorption is rinsed and potassium ion adsorption is performed in step (2). (5) First, the intermediate potassium-rich solution from the 1st to the 4th BV obtained in step (3) is heated to 70-90°C and used as a desorbent at a flow rate of 2-4 BV / h to desorb the adsorption column that has undergone potassium ion adsorption in step (4). Then, the lithium precipitation mother liquor generated during the lithium extraction process in the salt lake is heated to 70-90°C and used as a desorbent at a flow rate of 2-4 BV / h to desorb the final potassium-rich solution product. In the lithium precipitation mother liquor, Na + The content is 10-30g / L, K + The content of lithium is 0.1-0.6 g / L; the pH value of the lithium precipitation mother liquor is 12-14.
[0041] In other implementations, such as Figure 1 As shown, the method for potassium extraction using brine adsorption in salt lakes according to the present invention includes the following steps: (1) The zeolite adsorbent is pulverized to 20-60 mesh, washed with water, and then dried at 80-90℃ for 2-3 hours to obtain a pretreated zeolite adsorbent. The pretreated zeolite adsorbent is then modified with lithium precipitation mother liquor generated during the lithium extraction process in the salt lake by shaking or stirring at 80-90℃ for 2-3 hours, and the modification is repeated 2-4 times to obtain a modified zeolite adsorbent. The modified zeolite adsorbent is then rinsed with water and dried at 80-90℃ for 2-3 hours. The mass ratio of the zeolite adsorbent to the lithium precipitation mother liquor is 1:(2-4). In the lithium precipitation mother liquor, Na + The content is 15-30g / L, K +The content is 0.1-0.3 g / L; the pH value of the lithium precipitation mother liquor is 12-13; (2) The modified zeolite adsorbent is packed into an adsorption column, the salt lake brine is filtered and the temperature is adjusted to 30-40℃, and then the salt lake brine is passed through the adsorption column at a feed flow rate of 2-4 BV / h for potassium ion adsorption. In the salt lake brine, the concentration of potassium ions is 6-8 g / L, the concentration of magnesium ions is 20-25 g / L, the concentration of calcium ions is 1-2 g / L, the concentration of sodium ions is 70-80 g / L, and the concentration of chloride ions is 170-180 g / L. (3) The lithium precipitation mother liquor produced during the lithium extraction process in the salt lake is heated to 80-90℃ and used as a desorbent at a flow rate of 2-3 BV / h to desorb the adsorption column that has undergone potassium ion adsorption in step (2), thereby obtaining an intermediate potassium-rich solution. In the lithium precipitation mother liquor, Na + The content is 15-30g / L, K + The content is 0.1-0.3 g / L; the pH value of the lithium precipitation mother liquor is 12-13; (4) After desorption in step (3), the adsorption column after desorption is rinsed and potassium ion adsorption is performed in step (2). (5) First, the intermediate potassium-rich solution from the 1st to the 4th BV obtained in step (3) is heated to 70-90°C and used as a desorbent at a flow rate of 2-4 BV / h to desorb the adsorption column that has undergone potassium ion adsorption in step (4). Then, the lithium precipitation mother liquor generated during the lithium extraction process in the salt lake is heated to 70-90°C and used as a desorbent at a flow rate of 2-4 BV / h to desorb the final potassium-rich solution product. In the lithium precipitation mother liquor, Na + The content is 15-30g / L, K + The content of lithium is 0.1-0.3 g / L; the pH value of the lithium precipitation mother liquor is 12-13.
[0042] The following examples further illustrate the method for potassium extraction using adsorption from raw brine in salt lakes according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.
[0043] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.
[0044] Test Example 1 (1) 100g of natural clinoptilolite was crushed to 20-60 mesh, washed with pure water, and then dried at 90℃ for 2h to obtain pretreated zeolite adsorbent. Then, 300mL of lithium precipitation mother liquor generated during the lithium extraction process in the salt lake (in the lithium precipitation mother liquor, Na + The content is 15g / L, K + The content of lithium is 0.3 g / L, and the pH value of the lithium precipitation mother liquor is 13). The pretreated zeolite adsorbent is modified in an 80°C constant temperature water bath at a stirring rate of 130 rpm for 2 h, filtered, and this modification process is repeated 3 times to obtain the modified zeolite adsorbent. Then the modified zeolite adsorbent is rinsed with deionized water and then dried at 90°C for 2 h. (2) The modified zeolite adsorbent was wet-packed into an adsorption column (column volume 100mL). The original brine of the salt lake (in the original brine of the salt lake, the content of potassium ions is 6g / L, the concentration of magnesium ions is 23g / L, the concentration of calcium ions is 1.9g / L, the concentration of sodium ions is 75g / L, and the concentration of chloride ions is 175g / L) was filtered and the temperature was adjusted to 30°C. Then the original brine of the salt lake was passed through the adsorption column at a feed flow rate of 4BV / h for potassium ion adsorption for 4h. (3) The lithium precipitation mother liquor generated during the lithium extraction process in the salt lake (in the lithium precipitation mother liquor, Na + The content is 15g / L, K + The content of the lithium is 0.3 g / L, and the pH value of the lithium precipitation mother liquor is 13). The adsorption column that has undergone potassium ion adsorption in step (2) is heated to 80°C and desorbed at a flow rate of 3 BV / h for 3 h to obtain potassium-rich solution. After the desorption, the adsorption column is rinsed and returned to step (2) for reuse. Steps (2)-(3) are repeated for 5 adsorption-desorption cycles (the adsorption capacity of each cycle is recorded in Table 1). The potassium-rich solution obtained by desorption is collected, and the decay rate is 4.8%.
[0045] Test Example 2 (1) 100g of natural clinoptilolite was crushed to 20-60 mesh, washed with pure water, and then dried at 90℃ for 2h to obtain pretreated zeolite adsorbent. Then, 300mL of lithium precipitation mother liquor generated during the lithium extraction process in the salt lake (in the lithium precipitation mother liquor, Na + The content is 15g / L, K + The content of lithium is 0.3 g / L, and the pH value of the lithium precipitation mother liquor is 13). The pretreated zeolite adsorbent is modified in an 80°C constant temperature water bath at a stirring rate of 130 rpm for 2 h, filtered, and this modification process is repeated 3 times to obtain the modified zeolite adsorbent. Then the modified zeolite adsorbent is rinsed with deionized water and then dried at 90°C for 2 h. (2) The modified zeolite adsorbent was wet-packed into an adsorption column (column volume 100mL). The original brine of the salt lake (in the original brine of the salt lake, the content of potassium ions is 6g / L, the concentration of magnesium ions is 25g / L, the concentration of calcium ions is 2g / L, the concentration of sodium ions is 75g / L, and the concentration of chloride ions is 170g / L) was filtered and the temperature was adjusted to 30°C. Then the original brine of the salt lake was passed through the adsorption column at a feed flow rate of 4BV / h for potassium ion adsorption for 4h. (3) The lithium precipitation mother liquor generated during the lithium extraction process in the salt lake (in the lithium precipitation mother liquor, Na + The content is 15g / L, K + The content of the lithium is 0.3 g / L, and the pH value of the lithium precipitation mother liquor is 13. The adsorption column that has undergone potassium ion adsorption in step (2) is heated to 80°C and desorbed at a flow rate of 2 BV / h to obtain a potassium-rich solution (the concentration of potassium ions in the potassium-rich solution is recorded when the potassium-rich solution is 1-15 BV). Figure 1 ).
[0046] Test Example 3 (1) 100g of natural clinoptilolite was crushed to 20-60 mesh, washed with pure water, and then dried at 90℃ for 2h to obtain pretreated zeolite adsorbent. Then, 300mL of lithium precipitation mother liquor generated during the lithium extraction process in the salt lake (in the lithium precipitation mother liquor, Na + The content is 15g / L, K + The content of lithium is 0.3 g / L, and the pH value of the lithium precipitation mother liquor is 13). The pretreated zeolite adsorbent is modified in an 80°C constant temperature water bath at a stirring rate of 130 rpm for 2 h, filtered, and this modification process is repeated 3 times to obtain the modified zeolite adsorbent. Then the modified zeolite adsorbent is rinsed with deionized water and then dried at 90°C for 2 h. (2) The modified zeolite adsorbent was wet-packed into an adsorption column (column volume 100 mL). The original brine of the salt lake (in the original brine of the salt lake, the content of potassium ions is 6 g / L, the concentration of magnesium ions is 25 g / L, the concentration of calcium ions is 2 g / L, the concentration of sodium ions is 75 g / L, and the concentration of chloride ions is 170 g / L) was filtered and the temperature was adjusted to 30°C. Then the original brine of the salt lake was passed through the adsorption column at a feed flow rate of 4 BV / h for potassium ion adsorption. (3) The lithium precipitation mother liquor generated during the lithium extraction process in the salt lake (in the lithium precipitation mother liquor, Na + The content is 15g / L, K + The content of the lithium is 0.3 g / L, and the pH value of the lithium precipitation mother liquor is 13. The liquor is heated to 80°C and desorbed from the adsorption column after potassium ion adsorption in step (2) at a flow rate of 4 BV / h to obtain a potassium-rich solution (the concentration of potassium ions in the potassium-rich solution is recorded when the potassium-rich solution is 1-15 BV). Figure 1 ).
[0047] Example 1 (1) 100g of natural clinoptilolite was crushed to 20-60 mesh, washed with pure water, and then dried at 90℃ for 2h to obtain pretreated zeolite adsorbent. Then, 300mL of lithium precipitation mother liquor generated during the lithium extraction process in the salt lake (in the lithium precipitation mother liquor, Na + The content is 15g / L, K + The content of lithium is 0.3 g / L, and the pH value of the lithium precipitation mother liquor is 13). The pretreated zeolite adsorbent is modified in an 80°C constant temperature water bath at a stirring rate of 130 rpm for 2 h, filtered, and this modification process is repeated 3 times to obtain the modified zeolite adsorbent. Then the modified zeolite adsorbent is rinsed with deionized water and then dried at 90°C for 2 h. (2) The modified zeolite adsorbent was wet-packed into an adsorption column (column volume 100 mL). The original brine of the salt lake (in the original brine of the salt lake, the content of potassium ions is 6 g / L, the concentration of magnesium ions is 23 g / L, the concentration of calcium ions is 1.9 g / L, the concentration of sodium ions is 75 g / L, and the concentration of chloride ions is 175 g / L) was filtered and the temperature was adjusted to 30°C. Then the original brine of the salt lake was passed through the adsorption column at a feed flow rate of 4 BV / h for potassium ion adsorption for 4 h (the adsorption capacity of potassium ions was recorded in Table 2). (3) The lithium precipitation mother liquor generated during the lithium extraction process in the salt lake (in the lithium precipitation mother liquor, Na + The content is 15g / L, K + The content of the lithium is 0.3 g / L, and the pH value of the lithium precipitation mother liquor is 13). The liquor is heated to 80°C and desorbed at a flow rate of 3 BV / h as the desorbent to desorb the adsorption column that has undergone potassium ion adsorption in step (2) for 3 h to obtain intermediate potassium-rich liquor. (4) After desorption in step (3), the adsorption column after desorption is rinsed and potassium ion adsorption is performed in step (2). (5) First, use the intermediate potassium-rich solution from the 1st BV to the 4th BV obtained in step (3) to heat to 80°C and use a flow rate of 3 BV / h as the desorbent to desorb the adsorption column that has undergone potassium ion adsorption in step (4) for 80 min. Then, use the lithium precipitation mother liquor generated during the lithium extraction process in the salt lake to heat to 80°C and use a flow rate of 3 BV / h as the desorbent to desorb for 100 min to obtain the final potassium-rich solution product (the concentration of potassium ions in the final potassium-rich solution product is recorded in Table 2).
[0048] Example 2 Potassium extraction was performed according to the method in Example 1, except that the natural clinoptilolite was pulverized to 6-8 mesh, and the concentration of potassium ions and the adsorption capacity of potassium ions in the final potassium-rich liquid product were recorded in Table 2.
[0049] Example 3 Potassium extraction was performed according to the method in Example 1, except that natural clinoptilolite was pulverized to 8-10 mesh, and the concentration of potassium ions and the adsorption capacity of potassium ions in the final potassium-rich liquid product were recorded in Table 2.
[0050] Example 4 Potassium extraction was performed according to the method in Example 1, except that natural clinoptilolite was pulverized to 10-18 mesh, and the concentration of potassium ions and the adsorption capacity of potassium ions in the final potassium-rich liquid product were recorded in Table 2.
[0051] Example 5 Potassium was extracted according to the method of Example 1, except that the temperature of modification in step (1) was 70°C. The concentration of potassium ions and the adsorption capacity of potassium ions in the final potassium-rich liquid product were recorded in Table 2.
[0052] Example 6 Potassium was extracted according to the method of Example 1, except that the temperature of modification in step (1) was 90°C. The concentration of potassium ions and the adsorption capacity of potassium ions in the final potassium-rich liquid product were recorded in Table 2.
[0053] Example 7 (1) 100g of natural clinoptilolite was crushed to 20-60 mesh, washed with pure water, and then dried at 90℃ for 2h to obtain pretreated zeolite adsorbent. Then, 200mL of lithium precipitation mother liquor generated during the lithium extraction process in the salt lake (in the lithium precipitation mother liquor, Na + The content is 30g / L, K + The content of lithium is 0.6 g / L, and the pH value of the lithium precipitation mother liquor is 12. The pretreated zeolite adsorbent is modified for 1 h in a constant temperature water bath at 80℃ with a stirring rate of 130 rpm. After filtration, the modification process is repeated 4 times to obtain the modified zeolite adsorbent. Then the modified zeolite adsorbent is rinsed with deionized water and then dried at 90℃ for 2 h. (2) The modified zeolite adsorbent was wet-packed into an adsorption column (column volume 100 mL). The original brine of the salt lake (in the original brine of the salt lake, the content of potassium ions is 8 g / L, the concentration of magnesium ions is 20 g / L, the concentration of calcium ions is 1 g / L, the concentration of sodium ions is 60 g / L, and the concentration of chloride ions is 170 g / L) was filtered and the temperature was adjusted to 30°C. Then the original brine of the salt lake was passed through the adsorption column at a feed flow rate of 2 BV / h for potassium ion adsorption for 4 h (the adsorption capacity of potassium ions was recorded in Table 2). (3) The lithium precipitation mother liquor generated during the lithium extraction process in the salt lake (in the lithium precipitation mother liquor, Na + The content is 30g / L, K +The content of the lithium is 0.6 g / L, and the pH value of the lithium precipitation mother liquor is 12). The liquor is heated to 70°C and desorbed at a flow rate of 2 BV / h as the desorbent to desorb the adsorption column that has undergone potassium ion adsorption in step (2) for 3 hours to obtain intermediate potassium-rich liquor. (4) After desorption in step (3), the adsorption column after desorption is rinsed and potassium ion adsorption is performed in step (2). (5) First, use the intermediate potassium-rich solution from the 1st BV to the 4th BV obtained in step (3) to heat to 70°C and use a flow rate of 2 BV / h as the desorbent to desorb the adsorption column that has undergone potassium ion adsorption in step (4) for 80 min. Then, use the lithium precipitation mother liquor generated during the lithium extraction process in the salt lake to heat to 80°C and use a flow rate of 2 BV / h as the desorbent to desorb for 100 min to obtain the final potassium-rich solution product (the concentration of potassium ions in the final potassium-rich solution product is recorded in Table 2).
[0054] Example 8 (1) 100g of natural clinoptilolite was crushed to 20-60 mesh, washed with pure water, and then dried at 90℃ for 2h to obtain pretreated zeolite adsorbent. Then, 400mL of lithium precipitation mother liquor generated during the lithium extraction process in the salt lake (in the lithium precipitation mother liquor, Na + The content is 10g / L, K + The content of lithium is 0.1 g / L, and the pH value of the lithium precipitation mother liquor is 14. The pretreated zeolite adsorbent is modified in an 80°C constant temperature water bath at a stirring rate of 130 rpm for 3 h, filtered, and this modification process is repeated twice to obtain the modified zeolite adsorbent. Then the modified zeolite adsorbent is rinsed with deionized water and then dried at 90°C for 2 h. (2) The modified zeolite adsorbent was wet-packed into an adsorption column (column volume 100 mL). The original brine of the salt lake (in the original brine of the salt lake, the content of potassium ions is 10 g / L, the concentration of magnesium ions is 30 g / L, the concentration of calcium ions is 3 g / L, the concentration of sodium ions is 80 g / L, and the concentration of chloride ions is 190 g / L) was filtered and the temperature was adjusted to 30°C. Then the original brine of the salt lake was passed through the adsorption column at a feed flow rate of 6 BV / h for potassium ion adsorption for 4 h (the adsorption capacity of potassium ions was recorded in Table 2). (3) The lithium precipitation mother liquor generated during the lithium extraction process in the salt lake (in the lithium precipitation mother liquor, Na + The content is 10g / L, K + The content of the lithium is 0.1 g / L, and the pH value of the lithium precipitation mother liquor is 14). The liquor is heated to 90°C and desorbed at a flow rate of 4 BV / h as the desorbent to desorb the adsorption column that has undergone potassium ion adsorption in step (2) for 3 hours to obtain intermediate potassium-rich liquor. (4) After desorption in step (3), the adsorption column after desorption is rinsed and potassium ion adsorption is performed in step (2). (5) First, use the intermediate potassium-rich solution from the 1st BV to the 4th BV obtained in step (3) to heat to 90°C and use a flow rate of 4 BV / h as the desorbent to desorb the adsorption column that has undergone potassium ion adsorption in step (4) for 80 min. Then, use the lithium precipitation mother liquor generated during the lithium extraction process in the salt lake to heat to 90°C and use a flow rate of 4 BV / h as the desorbent to desorb for 100 min to obtain the final potassium-rich solution product (the concentration of potassium ions in the final potassium-rich solution product is recorded in Table 2).
[0055] Comparative Example 1 Potassium was extracted according to the method of Example 5, except that the lithium precipitation mother liquor in step (1) was replaced with a sodium chloride aqueous solution with a concentration of 20 wt%. The concentration of potassium ions and the adsorption capacity of potassium ions in the final potassium-rich liquid product are recorded in Table 2.
[0056] Comparative Example 2 Lithium extraction was performed according to the method in Example 5, except that the lithium precipitation mother liquor in step (3) was replaced with a sodium chloride aqueous solution with a concentration of 20 wt%. The concentration of potassium ions and the adsorption capacity of potassium ions in the final potassium-rich liquid product are recorded in Table 2.
[0057] Table 1
[0058] As can be seen from the results in Table 1, the modified zeolite structure in Example 1 of the method for potassium extraction by adsorption from salt lake brine of the present invention is stable, and its performance decay rate is extremely low after multiple cycles of adsorption and desorption.
[0059] Table 2
[0060] As shown in Table 2, compared with Comparative Examples 1 and 2, Examples 1-8 using the method of potassium extraction by adsorption from salt lake brine of the present invention have higher potassium ion concentration and potassium ion adsorption capacity in the potassium-rich solution, lower cost, and achieve waste liquid utilization. Furthermore, the modified zeolite adsorbent with different particle sizes and the modification temperature both affect the potassium ion adsorption capacity, with the highest adsorption capacity observed when the modified zeolite adsorbent has a mesh size of 20-60 and the modification temperature is 80℃.
[0061] from Figure 2 It can be seen that K in potassium-rich solution at 2-3 BV +The concentration reached its peak. Overall, it showed a trend of first increasing and then decreasing, indicating that both excessively high and excessively low flow rates of the lithium precipitation mother liquor in step (3) would have an adverse effect on the enrichment effect. The reason for this is that during the desorption process, the mass transfer resistance mainly comes from the diffusion of ions in the stagnant liquid film and the ion diffusion of ions inside the zeolite. When the lithium precipitation mother liquor in step (3) uses a low flow rate, the turbulence of the lithium precipitation mother liquor between the zeolite is low, and the stagnant liquid film between the zeolite and the main body of the lithium precipitation mother liquor in step (3) thickens, which increases the mass transfer resistance in this process and leads to a decrease in the desorption effect. However, if the feed flow rate of the lithium precipitation mother liquor in step (3) is too high, the residence time of the desorbed liquid inside the zeolite is too short, so that the lithium precipitation mother liquor cannot have sufficient ion exchange with the zeolite column, which may also lead to a low potassium ion content in the obtained potassium-rich solution.
[0062] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for extracting potassium from salt lake brine by adsorption, characterized in that, The method comprises the following steps: (1) crushing, washing and drying a zeolite adsorbent to obtain a pretreated zeolite adsorbent, and then modifying the pretreated zeolite adsorbent with a lithium precipitation mother liquor generated in a salt lake lithium extraction process to obtain a modified zeolite adsorbent; (2) loading the modified zeolite adsorbent into an adsorption column, and passing a salt lake raw brine through the adsorption column for potassium ion adsorption; (3) using the lithium precipitation mother liquor generated in the salt lake lithium extraction process as a desorption agent to desorb the adsorption column subjected to the potassium ion adsorption in step (2), to obtain an intermediate potassium-rich liquid; (4) after the desorption in step (3), flushing the desorbed adsorption column, and then performing the potassium ion adsorption according to step (2); (5) using the first 1BV to 4BV of the intermediate potassium-rich liquid obtained in step (3) as a desorption agent to desorb the adsorption column subjected to the potassium ion adsorption in step (4), and then using the lithium precipitation mother liquor generated in the salt lake lithium extraction process as a desorption agent to desorb the adsorption column, to obtain a final potassium-rich liquid product.
2. The method of claim 1, wherein, In step (1), the zeolite adsorbent is crushed to 20-60 mesh; Preferably, the zeolite adsorbent is natural clinoptilolite and / or artificially synthesized zeolite.
3. The method according to claim 1 or 2, characterized in that, In step (1), the content of Na + is 10-30 g / L, the content of K + is 0.1-0.6 g / L; the pH value of the lithium precipitation mother liquor is 12-14.
4. The method according to any one of claims 1 to 3, characterized in that, In step (1), the modification conditions include a temperature of 70-90℃ and a time of 1-3h.
5. The method according to any one of claims 1 to 4, characterized in that, In step (1), the mass ratio of the amount of the zeolite adsorbent to the amount of the lithium precipitation mother liquor is 1:(2-4).
6. The method according to any one of claims 1 to 5, characterized in that, In the salt lake raw brine, the concentration of potassium ions is 6-10g / L, the concentration of magnesium ions is 20-30g / L, the concentration of calcium ions is 1-3g / L, the concentration of sodium ions is 60-80g / L, and the concentration of chloride ions is 170-190g / L.
7. The method according to any one of claims 1 to 6, characterized in that, The method further comprises, before step (2), filtering and adjusting the temperature of the salt lake raw brine.
8. The method according to any one of claims 1 to 7, characterized in that, In step (2), the feeding flow rate of the salt lake raw brine is 2-6BV / h.
9. The method according to any one of claims 1 to 8, characterized in that, In step (3), the content of Na + is 10-30 g / L, the content of K + is 0.1-0.6 g / L; the pH value of the lithium precipitation mother liquor is 12-14.
10. The method according to any one of claims 1-9, characterized in that, In step (3), the temperature of the lithium precipitation mother liquor is 70-90℃, and the flow rate is 2-4BV / h.