Alkaline brine adsorption lithium extraction method

Abstract

The invention discloses a method for extracting lithium through adsorption of alkaline brine, and belongs to the technical field of application of new chemical materials. The lithium extraction work of alkaline brine is completed by comprehensively utilizing three types of lithium ion sieves, specifically, firstly, a titanium oxide lithium ion sieve is used for carrying out first-time adsorption lithium extraction on brine with relatively strong alkalinity, then a manganese oxide lithium ion sieve is used for carrying out second-time adsorption lithium extraction after a weakly alkaline first-stage adsorption tail liquid is obtained, and the second-stage adsorption tail liquid is neutral or weakly acidic; and finally, carrying out third adsorption and lithium extraction by using an aluminum salt lithium adsorbent. According to the scheme, the advantages and limitation of the three lithium ion sieves are comprehensively considered, the advantages of the different types of ion sieves are fully played by controlling the process, and the respective defects are effectively avoided, so that the adsorption capacity of the ion sieves and the comprehensive yield of lithium both reach a relatively high level; the method for extracting the lithium resource in the alkaline brine is economical and efficient, and the lithium resource in the salt lake brine can be fully utilized.

Description

Technical Field

[0001] The invention relates to the technical field of application of new chemical materials, and in particular to a multi-stage utilization method of tail liquid extracted by adsorption of lithium from alkaline brine. Background Art

[0002] With the rapid development of the new energy industry in recent years, the demand for lithium-ion power batteries has increased dramatically, and lithium salts, as the upstream raw materials for the production of lithium batteries, have been in short supply.

[0003] Lithium salts in nature mainly exist in ores, salt lakes, lithium battery recovery fluids, oil fields and seawater. According to relevant research, liquid lithium resources in salt lake brines are abundant, accounting for about 68% of the total lithium resources. Extracting lithium from salt lake brines containing a large amount of lithium resources is an important direction for obtaining lithium resources.

[0004] Traditional lithium extraction technologies include membrane separation, extraction, salt pan drying, etc. The shortcomings of these methods are high cost, high requirements for the taste of brine, serious environmental pollution, and large land occupation. Adsorption lithium extraction technology is a new type of salt lake lithium extraction process that has developed rapidly in recent years. This process uses a lithium adsorbent with a certain structure to selectively adsorb lithium ions from lithium-containing brine, and then elutes the lithium ions to separate lithium ions from other ions, which is convenient for subsequent processing and utilization. While efficiently extracting lithium, the overall recovery rate of lithium exceeds 90%, greatly improving the value and utilization of lithium resources. In addition, this method has little pollution to the water body during use and is relatively low in cost. It can extract lithium salts from salt lakes and leave the remaining components of brine in the lake. It is the most competitive development direction for lithium extraction from salt lakes.

[0005] The adsorbents used in the adsorption method are generally divided into two categories: inorganic adsorbents and organic adsorbents. Organic adsorbents are mainly ion exchange resins, which have poor selectivity and are difficult to elute; inorganic lithium extraction adsorbents are a type of metal oxide lithium ion sieve, such as titanium oxide lithium ion sieve, manganese oxide lithium ion sieve, or aluminum salt molecular sieve, which has high selectivity for lithium, large adsorption capacity, and high elution rate. It is an adsorbent material that is widely used in lithium extraction from salt lake brine. Selecting a suitable ion sieve to extract lithium through adsorption is a very promising method of lithium extraction.

[0006] However, it has been found through research that when the object of lithium extraction is strongly alkaline brine, except for titanium-based lithium extraction adsorbents that can be directly used for adsorption and extraction of lithium, manganese-based and aluminum-based lithium extraction adsorbents are difficult to deal with directly. Titanium oxide lithium ion sieve has strong alkali resistance and can be used in strongly alkaline brine for a long time, and the stronger the alkalinity, the higher its adsorption capacity, so it is mainly suitable for alkaline salt lakes rich in hydroxide; manganese oxide lithium ion sieve has high adsorption capacity and fast adsorption rate, but its alkali resistance is poor. When the pH value of the brine is high, there will be problems such as excessive adsorption rate leading to structural destruction of the adsorbent and increased dissolution loss, so it is suitable for adsorption and extraction of lithium from weak alkaline to neutral brine; aluminum salt molecular sieve adsorbents are very sensitive to hydroxide, carbonate, and bicarbonate in brine, because hydroxide can cause the crystal form of layered aluminum adsorbents to change and lose lithium ion selectivity, and carbonate and bicarbonate can poison aluminum adsorbents and cause a sharp drop in adsorption capacity, but aluminum-based adsorbents can adsorb and extract lithium in weakly acidic brines without consuming acid, and have good cycle stability.

[0007] In the prior art, only one adsorbent is used to extract lithium from salt lake brine. For example, Chinese patent CN 117821775A discloses a method for extracting lithium from salt lake brine, which makes the adsorption rate of lithium ions in the brine ≥95% by performing multiple rounds of adsorption treatment on the salt lake brine. The adsorption resin column is filled with a titanium adsorbent. It points out that compared with the widely used aluminum adsorbent, the titanium adsorbent has a larger adsorption capacity for lithium ions, higher selectivity, and higher desorption rate. The titanium adsorbent has a stable structure and is not easy to dissolve during the lithium extraction process. It is especially suitable for carbonate salt lake brine with high alkalinity. However, in the process of lithium extraction, as the lithium extraction process develops, the pH value of the brine will change accordingly. Using only one type of adsorbent to extract lithium may not maximize the efficiency of lithium extraction, and will also affect the comprehensive yield of lithium.

[0008] Therefore, if we can comprehensively utilize the advantages of different adsorbents and propose a reasonable and easy-to-implement combined treatment process so that several adsorbents can play their respective advantages when dealing with alkaline brine systems, it will be expected to further reduce the dissolution loss of lithium ion sieves during use and further improve the comprehensive recovery of lithium in alkaline salt lake brine. Summary of the invention

[0009] The purpose of the present invention is to solve the deficiencies in the prior art and provide a multi-stage utilization method for tail liquid of alkaline brine adsorption for lithium extraction, which comprehensively utilizes three types of lithium ion sieves to extract lithium from alkaline brine, and through the control of the process, gives play to the respective advantages of different ion sieves, and completes the development of lithium resources in brine to the greatest extent under extremely economical conditions.

[0010] The technical solution of the present invention is: a method for extracting lithium by adsorption of alkaline brine, comprising the following steps:

[0011] Step 1: using titanium oxide lithium ion sieve to adsorb alkaline lithium-containing brine to obtain a primary adsorption tail liquid;

[0012] Step 2: using manganese oxide lithium ion sieve to adsorb the weakly alkaline primary adsorption tail liquid to obtain a secondary adsorption tail liquid;

[0013] Step 3: Use aluminum salt molecular sieve to adsorb the neutral or weakly acidic secondary adsorption tail liquid to obtain a tertiary adsorption tail liquid.

[0014] Furthermore, the alkaline lithium-containing brine in step one is one of salt lake brine, lithium battery recovery liquid, bauxite leaching liquid, and lithium precipitation mother liquor; the titanium oxide lithium ion sieve in step one is one of metatitanate lithium ion sieve, orthotitanate lithium ion sieve, and doped titanium oxide lithium ion sieve.

[0015] Furthermore, the pH value of the alkaline lithium-containing brine in step one is 8-14; further, the pH value of the first-stage adsorption tail liquid in step one is 7-9; the flow rate of the adsorption process is controlled to be 1-4BV / h, and the adsorption is stopped when the lithium concentration of the effluent reaches 70-95% of the initial feed concentration, and the tail water is discharged.

[0016] Furthermore, the desorption process in step 1 uses 0.1-0.5M HCl for desorption, the amount of desorption liquid is 1-2 times the volume of the adsorbent, and the desorption flow rate is 0.5-1.5BV / h; after desorption is completed, it is rinsed with a buffer solution of pH=8.

[0017] Furthermore, the manganese oxide lithium ion sieve in step 2 is one of LixMnyOz and doped manganese oxide lithium ion sieve; wherein 1<x<2, 1<y<6, 1<z<12.

[0018] Furthermore, the pH value of the secondary adsorption tail liquid in step 2 is 4-7, the flow rate of the adsorption process is controlled to be 1-4BV / h, and the adsorption is stopped when the lithium concentration of the effluent reaches 70-95% of the initial feed concentration, and the tail water is discharged.

[0019] Furthermore, in the desorption process in step 2, a mixed solution of 1-1.5M H2SO4 + 0.5-2M NaCl is used for desorption, with a flow rate of 1-2BV / h and a desorption temperature of 30-50°C.

[0020] Furthermore, the aluminum salt molecular sieve described in step three is one of a layered aluminum salt lithium adsorbent, a doped aluminum salt lithium adsorbent, and a coated aluminum salt lithium adsorbent. The flow rate of the adsorption process is 2-5BV / h. When the lithium concentration of the effluent reaches 70-95% of the initial feed concentration, the adsorption is stopped and the tail water is discharged; during the desorption process, a 1-4M NaCl solution with a pH of 6-7 is used for desorption, and the desorption flow rate is 1-4BV / h.

[0021] Furthermore, after the brine is adsorbed by three lithium adsorbents, the lithium concentration in the brine is less than 5 mg / L.

[0022] Furthermore, after the brine is adsorbed by three adsorbents, the comprehensive recovery rate of lithium is greater than 99%.

[0023] Furthermore, after multiple cycles, the adsorption capacity retention rate of the adsorbent is calculated by the following formula:

[0024]

[0025] Where η(N) is the capacity retention rate after N cycles, k loss is the single cycle dissolution rate, ε0 is the initial bed porosity, and α is an empirical parameter.

[0026] Beneficial Effects

[0027] The beneficial effects of the present invention are:

[0028] 1. This application comprehensively utilizes titanium oxide lithium ion sieve, manganese oxide lithium ion sieve and aluminum salt molecular sieve to extract lithium from alkaline brine, and uses three ion sieves to complete the adsorption and lithium extraction of brine in the alkaline, weakly alkaline, neutral or weakly acidic stages respectively. After fully considering the application advantages and limiting factors of different ion sieves during application, a specific operation process is formulated, which allows different types of ion sieves to maximize their respective advantages in the lithium extraction process so as to extract lithium resources in alkaline brine most efficiently, which is conducive to the full utilization of lithium resources in salt lake brine;

[0029] 2. This application fully considers the advantages of different types of ion sieves and the limitations of lithium extraction to formulate a specific lithium extraction plan. After limiting the application environment of different ion sieves, it can not only improve the lithium extraction efficiency, but also reduce the dissolution loss of lithium ion sieves during use, thereby increasing the cycle life of the ion sieve, so that it can still maintain a good adsorption state after more than 100 cycles;

[0030] 3. The alkaline brine adsorption method for extracting lithium disclosed in the present application can improve the recovery rate of lithium ions in alkaline brine. After adsorption by three adsorbents, the comprehensive recovery rate of lithium in alkaline brine is greater than 99%;

[0031] 4. The multi-stage adsorption method disclosed in the present application is used to extract lithium resources from alkaline brine, which can make up for the shortcomings of different adsorbents when used alone, and give full play to their respective advantages, so that the adsorption capacity of titanium oxide lithium ion sieve and manganese oxide lithium ion sieve in the continuous adsorption process can reach a high level;

[0032] 5. This application fully considers the acid-base environment applicable to different lithium ion sieves and formulates the final lithium extraction plan. When the brine is neutral or weakly acidic, aluminum salt lithium adsorbent is used. This method of use can improve the adsorption stability of this type of adsorbent in the brine system;

[0033] 6. This application breaks the conventional idea of ​​lithium extraction and is no longer limited to the use of a single ion screen for brine lithium extraction operations. It has strong comprehensive applicability and complements each other to fully play the role of making up for each other's shortcomings, so that the economy, operability and practicality of the lithium extraction plan have been significantly improved. This also provides a new idea for the efficient extraction of lithium from lithium storage materials with different properties in nature. DETAILED DESCRIPTION

[0034] Example 1

[0035] A method for extracting lithium by adsorption from alkaline brine comprises the following steps:

[0036] The first step is to use a layered metatitanate lithium ion sieve (prepared by an inorganic precipitation peptization method) to adsorb brine 1 (the indicators of brine 1 are as follows), and brine 1 passes through a fixed bed adsorption tower filled with titanium oxide adsorbent at a flow rate of 2BV / h (bed volume / hour). When the lithium concentration of the effluent reaches 90% of the initial concentration, the adsorption is stopped and the tail water is discharged as the adsorption tail liquid; 0.3M HCl solution is used for desorption, the amount of desorption liquid is 1.5 times the volume of the adsorbent, the desorption flow rate is 1BV / h, and the desorption temperature is 25°C; after desorption, the adsorbent is rinsed with a buffer solution of pH=8;

[0037] Cation analysis results in brine 1 (unit: mg / L)

[0038]

[0039] Step 2: Use Li 1.6 Mn 1.6 O4 (prepared by solid phase method) is used to adsorb the first-stage adsorption tail liquid, and the first-stage adsorption tail liquid passes through the manganese oxide adsorbent bed at a flow rate of 1-2BV / h. When the lithium concentration of the effluent reaches 90% of the initial concentration, the adsorption is stopped and the tail water is discharged as the adsorption tail liquid; 0.5MH2SO4+1MNaCl mixed solution is used for desorption, the flow rate is 0.8BV / h, the desorption temperature is 40℃, and the time is 1.5h. After desorption, the adsorbent is rinsed with deionized water to neutrality (pH≈7) to complete the regeneration;

[0040] The third step is to use a layered aluminum salt lithium adsorbent (add alkali solution to aluminum chloride solution, convert aluminum chloride into aluminum hydroxide, and then soak it in lithium chloride solution to obtain the obtained product) to adsorb the secondary adsorption tail liquid. The secondary adsorption tail liquid passes through the aluminum salt adsorbent bed at a flow rate of 3-4BV / h. When the lithium concentration of the effluent reaches 90% of the initial concentration, the adsorption is stopped and the tail water is discharged as the adsorption tail liquid; desorption is performed with 2M NaCl solution (pH = 6-7) at a desorption flow rate of 2BV / h, desorption is performed at room temperature for 1 hour, and after desorption, it is rinsed with deionized water to neutrality.

[0041] After 200 cycles of adsorption-desorption, the adsorption performance indicators of the adsorbent are as follows:

[0042]

[0043] Example 2

[0044] A method for extracting lithium by adsorption from alkaline brine comprises the following steps:

[0045] Step 1: Adsorb brine 2 (the indicators of brine 2 are as follows) using orthotitanate lithium ion sieve, brine 1 passes through a fixed bed adsorption tower filled with titanium oxide adsorbent at a flow rate of 3BV / h (bed volume / hour), and when the lithium concentration of the effluent (primary adsorption tail liquid) reaches 90% of the initial concentration, the adsorption is stopped and the tail water is discharged as the adsorption tail liquid; desorption is performed using 0.3M HCl solution, the amount of desorption liquid is 1.5 times the volume of the adsorbent, the desorption flow rate is 1BV / h, and the desorption temperature is 25°C; after desorption, the adsorbent is rinsed with a buffer solution of pH=8;

[0046] Brine 2 cation analysis results (unit: mg / L)

[0047]

[0048] Step 2: The first-stage adsorption tail liquid is adsorbed with LiMn2O4. The first-stage adsorption tail liquid passes through the manganese oxide adsorbent bed at a flow rate of 1-2BV / h. When the lithium concentration of the effluent reaches 90% of the initial concentration, the adsorption is stopped and the tail water is discharged as the adsorption tail liquid; 0.5MH2SO4+1M NaCl mixed solution is used for desorption, with a flow rate of 0.8BV / h, a desorption temperature of 40°C, and a time of 1.5h. After desorption, the adsorbent is rinsed with deionized water to neutrality (pH≈7) to complete regeneration;

[0049] Step 3: The secondary adsorption tail liquid is adsorbed with a layered aluminum salt lithium adsorbent, and the secondary adsorption tail liquid passes through the aluminum salt adsorbent bed at a flow rate of 3-4BV / h. When the lithium concentration of the effluent reaches 90% of the initial concentration, the adsorption is stopped and the tail water is discharged as the adsorption tail liquid; desorption is performed with a 2M NaCl solution (pH = 6-7), the desorption flow rate is 2BV / h, the desorption is performed at room temperature, the time is 1 hour, and after desorption, it is rinsed with deionized water to neutrality;

[0050] After 100 cycles of adsorption-desorption, the adsorption performance indicators are shown in the following table:

[0051]

[0052] Example 3

[0053] A method for extracting lithium by adsorption from alkaline brine comprises the following steps:

[0054] Step 1: Adsorb brine 3 (the indicators of brine 3 are as follows) using a layered metatitanate lithium ion sieve. Brine 1 passes through a fixed bed adsorption tower filled with titanium oxide adsorbent at a flow rate of 2BV / h (bed volume / hour). When the lithium concentration of the effluent (primary adsorption tail liquid) reaches 90% of the initial concentration, the adsorption is stopped and the tail water is discharged as the adsorption tail liquid; desorption is performed using a 0.3M HCl solution, the amount of desorption liquid is 1.5 times the volume of the adsorbent, the desorption flow rate is 1BV / h, and the desorption temperature is 25°C; after desorption, the adsorbent is rinsed with a buffer solution of pH=8;

[0055] Brine 3 cation analysis results (unit: mg / L)

[0056]

[0057] Step 2: Use Li4Mn5O 12 The first-stage adsorption tail liquid is subjected to adsorption treatment. The first-stage adsorption tail liquid passes through the manganese oxide adsorbent bed at a flow rate of 1-2BV / h. When the lithium concentration of the effluent reaches 90% of the initial concentration, the adsorption is stopped and the tail water is discharged as the adsorption tail liquid; 0.5MH2SO4+1MNaCl mixed solution is used for desorption, the flow rate is 0.8BV / h, the desorption temperature is 40°C, and the time is 1.5h. After desorption, the adsorbent is rinsed with deionized water to neutrality (pH≈7) to complete regeneration;

[0058] Step 3: The secondary adsorption tail liquid is adsorbed with a doped layered aluminum salt lithium adsorbent. The secondary adsorption tail liquid passes through the aluminum salt adsorbent bed at a flow rate of 3-4 BV / h. When the lithium concentration of the effluent reaches 90% of the initial concentration, the adsorption is stopped and desorbed with a 2M NaCl solution (pH = 6-7). The desorption flow rate is 2 BV / h, the desorption is carried out at room temperature for 1 hour, and the desorption is rinsed with deionized water to neutrality.

[0059] After 300 cycles of adsorption-desorption, the adsorption performance indicators are shown in the following table:

[0060]

[0061] Example 4

[0062] Titanium-based adsorbents are prone to pulverization during multiple cycles, resulting in a decrease in capacity retention. By constructing a capacity retention model based on adsorbent bed characteristics, powder loss rate, feed liquid flow characteristics and cycle number, the prediction model is based on the following concept: In each cycle, the particles lose volume due to dissolution, and change the bed porosity and particle size. The particle diameter decay process is set as:

[0063] d p (N) = d p0 ·(1-k loss ) 1 / 3

[0064] Among them, d p (N) is the average particle diameter after N cycles, d p0 is the average diameter of the initial particles (m), k loss is the single cycle dissolution rate (dimensionless).

[0065] Further assuming that the dissolution leads to a decrease in particle volume and the bed porosity increases with the number of cycles, it can be deduced that:

[0066] ε(N)=ε0+(1-ε0)·[1-(1-k loss ) N ]

[0067] ε(N) is the bed porosity after the Nth cycle, and ε0 is the initial bed porosity (dimensionless).

[0068] When the liquid flows through the bed, the mass transfer efficiency is related to the porosity, particle size and flow rate. The modified Sherwood number is used to characterize the mass transfer coefficient:

[0069]

[0070] k m is the mass transfer coefficient (m / s), which is the rate or effect of lithium ions (Li+) being transferred from the fluid (such as brine) to the surface of the adsorbent particles, and D is the lithium ion diffusion coefficient (m 2 / s), μ is the fluid viscosity (Pa·s), ρ is the fluid density (kg / m 3 ). The mass transfer efficiency decreases with the increase of porosity, and the correction factor is introduced:

[0071]

[0072] α is an empirical parameter, usually ranging from 0.5 to 1.0

[0073] The adsorption capacity retention rate is determined by the particle loss and mass transfer efficiency:

[0074]

[0075] β is the sensitivity coefficient of mass transfer to adsorption capacity (can be 1.0), substituted into the mass transfer coefficient expression:

[0076]

[0077] Then we get:

[0078]

[0079] The operating parameters in Example 1 were used to calculate the adsorption capacity retention rate after multiple cycles. The k loss ≈0.0026, α≈0.81.

[0080] The real experimental data and model prediction data generated based on the model are as follows:

[0081]

[0082]

[0083] It can be seen that the prediction accuracy of this patent is good, and the deviation from the true value is within 10%.

Claims

1. A method for extracting lithium by adsorption from alkaline brine, characterized in that: The following steps are involved: Step 1: using titanium oxide lithium ion sieve to adsorb alkaline lithium-containing brine to obtain a primary adsorption tail liquid; Step 2: using manganese oxide lithium ion sieve to adsorb the weakly alkaline primary adsorption tail liquid to obtain a secondary adsorption tail liquid; Step 3: Use aluminum salt molecular sieve to adsorb the neutral or weakly acidic secondary adsorption tail liquid to obtain a tertiary adsorption tail liquid.

2. The alkaline brine adsorption method for extracting lithium according to claim 1, characterized in that: The alkaline lithium-containing brine described in step one is one of salt lake brine, lithium battery recovery liquid, bauxite leaching liquid, and lithium precipitation mother liquor; the titanium oxide lithium ion sieve described in step one is one of metatitanate lithium ion sieve, orthotitanate lithium ion sieve, and doped titanium oxide lithium ion sieve.

3. The alkaline brine adsorption method for extracting lithium according to claim 1, characterized in that: The pH value of the alkaline lithium-containing brine in step one is 8-14; further, the pH value of the first-stage adsorption tail liquid in step one is 7-9; the flow rate of the adsorption process is controlled to be 1-4BV / h, and the adsorption is stopped when the lithium concentration of the effluent reaches 70-95% of the initial feed concentration, and the tail water is discharged.

4. The alkaline brine adsorption method for extracting lithium according to claim 1, characterized in that: In the desorption process of step 1, 0.1-0.5M HCl is used for desorption, the amount of desorption liquid is 1-2 times the volume of the adsorbent, and the desorption flow rate is 0.5-1.5BV / h; after desorption is completed, a buffer solution with pH=8 is used for washing.

5. The method for extracting lithium by adsorption from alkaline brine according to claim 1, characterized in that: The manganese oxide lithium ion sieve in step 2 is one of LixMnyOz and doped manganese oxide lithium ion sieve; wherein 1<x<2, 1<y<6, 1<z<12; the pH value of the secondary adsorption tail liquid in step 2 is 4-7, the flow rate of the adsorption process is controlled to be 1-4BV / h, and the adsorption is stopped when the lithium concentration of the effluent reaches 70-95% of the initial feed concentration, and the tail water is discharged.

6. The alkaline brine adsorption method for extracting lithium according to claim 1, characterized in that: During the desorption process in step 2, a mixed solution of 1-1.5M H2SO4 + 0.5-2M NaCl is used for desorption, with a flow rate of 1-2BV / h and a desorption temperature of 30-50°C.

7. The alkaline brine adsorption method for extracting lithium according to claim 1, characterized in that: The aluminum salt molecular sieve described in step three is one of a layered aluminum salt lithium adsorbent, a doped aluminum salt lithium adsorbent, and a coated aluminum salt lithium adsorbent. The flow rate of the adsorption process is 2-5BV / h. When the lithium concentration of the effluent reaches 70-95% of the initial feed concentration, the adsorption is stopped and the tail water is discharged; during the desorption process, a 1-4M NaCl solution with a pH of 6-7 is used for desorption, and the desorption flow rate is 1-4BV / h.

8. The method for extracting lithium by adsorption from alkaline brine according to claim 1, characterized in that: After the brine is adsorbed by the three lithium adsorbents, the lithium concentration in the brine is less than 5 mg / L; after the brine is adsorbed by the three adsorbents, the comprehensive recovery rate of lithium is greater than 99%.

9. The alkaline brine adsorption method for extracting lithium according to claim 1, characterized in that: After multiple cycles of the adsorbent, the adsorption capacity retention rate is calculated by the following formula: Where η(N) is the capacity retention rate after N cycles, k loss is the single cycle dissolution rate, ε0 is the initial bed porosity, and α is an empirical parameter.

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