Phosphoric acid modified aluminum-based lithium adsorbent and preparation method thereof, and method for preparing battery-grade lithium carbonate and co-producing potassium chloride from carbonate-type salt lake brine

Abstract

The present invention discloses a phosphoric acid-modified aluminum-lithium adsorbent and a method for preparing the same, as well as preparing battery-grade lithium carbonate and co-producing potassium chloride from carbonate-type salt lake brine. In the present invention, a polymer containing a styrene chain segment is dissolved in an organic solvent, a phosphating catalyst and phosphorus trichloride are added to carry out a phosphating reaction to obtain a phosphoric acid-modified polymer, which is then blended and granulated with an aluminum-lithium adsorbent to obtain a phosphoric acid-modified aluminum-lithium adsorbent. The phosphoric acid-modified aluminum-lithium adsorbent of the present invention solves the problem that traditional aluminum-lithium adsorbents are easily poisoned and deactivated in carbonate-type salt lakes, and can be directly applied to the lithium extraction process of carbonate-type salt lakes, and has the characteristics of long service life and long-term stable performance. The lithium extraction process of the present invention can directly produce battery-grade lithium carbonate and co-produce industrial-grade potassium chloride by coupling the aluminum-lithium adsorbent, a separation membrane and an ion exchange resin, and has the advantages of high automation and low construction and production costs. It is particularly suitable for extracting lithium from carbonate-type salt lake brine in areas such as Tibet.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium extraction from salt lakes, and specifically relates to a phosphoric acid-modified aluminum-based lithium adsorbent and a preparation method thereof, as well as a method for preparing battery-grade lithium carbonate and co-producing potassium chloride from carbonate-type salt lake brine using the same. Background Art

[0002] Lithium is a key raw material for the new energy industry, centered around lithium batteries. Its primary sources are salt lake brines and minerals. Nearly 80% of my country's lithium resources are located in salt lakes in Qinghai and Tibet. Among these, the carbonate salt lakes of Zhabuye, Jiezechaka, Bange Co, Dangxiong Co, and Guojialin Co in Tibet are rich in carbonate ions, resulting in extremely low calcium and magnesium content. This reduces the difficulty of separating magnesium from lithium, making them high-quality resources for lithium extraction from salt lake brines.

[0003] Currently, the main lithium extraction processes from carbonate salt lakes include the solar pond method, the brine addition method, and the adsorption-membrane method. The adsorption-membrane method has the advantages of high production efficiency, wide applicability, and low extraction cost, and is expected to become the mainstream process for lithium extraction from carbonate salt lakes. CN 114134327A discloses a process and apparatus for extracting lithium carbonate from carbonate salt lake brine using an adsorption-bipolar membrane method. Manganese or titanium adsorbents are used to adsorb carbonate ions from the tail brine, which serve as a carbon source in the lithium carbonate preparation process. The acid and alkali obtained by treating the lithium precipitation mother liquor with bipolar membrane technology are then used in the front-end process, saving raw material costs and improving lithium recovery. However, the dissolution loss problem of the manganese or titanium adsorbents used in this process during the acid washing and desorption process cannot be completely overcome. Furthermore, the adsorbed tail brine is not refined and impurity-removed, resulting in a high level of impurity ion interference in the lithium precipitation reaction, which may cause the lithium carbonate product to contain excessive levels of impurities such as calcium, silicon, magnesium, and boron, failing to reach battery grade. Furthermore, the high construction cost of the bipolar membrane device cannot be effectively resolved in the short term. CN 112624160 A discloses a method for producing lithium carbonate by combining an aluminum-based lithium adsorbent, a nanofiltration membrane, and a reverse osmosis membrane, while simultaneously utilizing brine freeze-denitrification to produce sodium carbonate. However, after the carbonate-based brine is treated with the nanofiltration membrane, a small amount of carbonate ions remains. This can easily lead to inactivation of the aluminum-based lithium adsorbent and loss of adsorption effectiveness during long-term operation. This method does not purify the brine, making it difficult to ensure the purity of the lithium carbonate product. Furthermore, the method can only produce lithium carbonate products, resulting in high production costs. Summary of the Invention

[0004] In response to the above-mentioned deficiencies in the prior art, one of the objectives of the present invention is to provide a phosphoric acid-modified aluminum-based lithium adsorbent and a preparation method thereof. The phosphoric acid-modified aluminum-based lithium adsorbent solves the problem that traditional aluminum-based lithium adsorbents are easily poisoned and deactivated in carbonate salt lakes. It can be directly applied to the lithium extraction process of carbonate salt lakes, and solves the problems of existing adsorbent dissolution, excessive impurity content, and residual carbonate. It has the characteristics of long service life and stable performance over a long period of time.

[0005] One of the objectives of the present invention is to provide a method for preparing battery-grade lithium carbonate and co-producing potassium chloride from carbonate-type salt lake brine. This method can directly produce battery-grade lithium carbonate and co-produce industrial-grade potassium chloride through the coupling of the above-mentioned phosphoric acid-modified aluminum-based lithium adsorbent, separation membrane and ion exchange resin. It has the advantages of high degree of automation and low construction and production costs, and is particularly suitable for extracting lithium from carbonate-type salt lake brine in Tibet and other regions.

[0006] In order to achieve the above objectives, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a phosphoric acid-modified aluminum-based lithium adsorbent, comprising the following steps:

[0008] (1) dissolving a polymer containing a styrene chain segment in an organic solvent, adding a phosphating catalyst and phosphorus trichloride to carry out a phosphating reaction, and after the reaction is completed, washing with alkali and acid to obtain a phosphoric acid-modified polymer;

[0009] (2) The phosphoric acid-modified polymer of step (1) is blended and granulated with an aluminum-based lithium adsorbent to obtain a phosphoric acid-modified aluminum-based lithium adsorbent.

[0010] In step (1) of the present invention, the The polymer is selected from one or more of polystyrene, polystyrene halide, copolymers of styrene and acrylic ester monomers, and copolymers of styrene and olefin monomers, preferably one or more of polystyrene, chlorinated polystyrene, brominated polystyrene, styrene-methyl methacrylate copolymer, styrene-isoprene copolymer, and acrylonitrile-butadiene-styrene copolymer;

[0011] The molar content of styrene chain segments in the polymer containing styrene chain segments is 50 to 100%, preferably 70 to 100%;

[0012] The number average molecular weight of the polymer containing styrene chain segments is 50,000 to 300,000 Daltons, preferably 100,000 to 250,000.

[0013] In step (1) of the present invention, the organic solvent is selected from one or more of dichloroethane, nitrobenzene, and dichloropropane;

[0014] The mass ratio of the polymer containing styrene chain segments to the organic solvent is 1:10 to 1:100, preferably 1:20 to 1:80.

[0015] In step (1) of the present invention, the phosphating catalyst is selected from one or more of aluminum chloride, ferric chloride, and zinc chloride;

[0016] The mass ratio of the phosphating catalyst to the organic solvent is 1:100 to 1:1000, preferably 1:200 to 1:800.

[0017] In step (1) of the present invention, the mass ratio of the phosphorus trichloride to the polymer containing styrene chain segments is 1:1 to 1:20, preferably 1:5 to 1:15.

[0018] In step 1) of the present invention, the phosphating reaction is carried out at a temperature of 15 to 45° C., preferably 25 to 40° C., and for a time of 1 to 8 hours, preferably 2 to 6 hours.

[0019] In step (1) of the present invention, after the reaction is completed, the solvent is preferably replaced with ethanol, and then the polymer is washed with alkali, acid, and then washed with water and dried to obtain a phosphoric acid-modified polymer. The ethanol replacement of the solvent, alkali washing, acid washing, water washing, and drying can be carried out by conventional means in the art and are not particularly required by the present invention. For example, in some examples of the present invention, the specific method used is to add ethanol to replace the organic solvent in the system, and then sequentially add 4wt% sodium hydroxide aqueous solution, 4wt% hydrochloric acid, and water for washing, and then dry to obtain a phosphoric acid-modified polymer.

[0020] In step (1) of the present invention, the phosphoric acid-substituted polystyrene segment in the phosphoric acid-modified polymer The molar ratio is 25 to 50%.

[0021] In step (2) of the present invention, the aluminum-based lithium adsorbent is selected from an adsorbent having the general formula LiCl·mAl(OH)3·nH2O, wherein m=2-3 and n=2-4;

[0022] The aluminum-based lithium adsorbent is an inorganic powder with a particle size of 0.5 to 50 μm, preferably 1 to 30 μm.

[0023] The aluminum-based lithium adsorbent of the general formula LiCl·mAl(OH)3·nH2O of the present invention is an existing product and can be purchased on the market or prepared by itself. The present invention has no special requirements. For example, the preparation method can be prepared according to the co-precipitation method conventionally used in the field, and obtained by co-precipitation reaction of lithium salt (such as LiCl), aluminum salt (such as AlCl3) and alkaline substance (such as NaOH) (Wu Zhijian et al., Mechanism of Adsorption of Lithium from Brine by Aluminum Hydroxide-based Lithium Adsorbent, Salt Lake Research, 2018, 26(3)), or prepared by referring to the method disclosed in patent CN106076243A. The specific preparation process will not be repeated in this invention.

[0024] In step (2) of the present invention, the mass ratio of the phosphoric acid-modified polymer to the aluminum-based lithium adsorbent is 1:5 to 2:1, preferably 1:4 to 1:1;

[0025] The phosphoric acid-modified polymer and the aluminum-based lithium adsorbent inorganic powder are blended and granulated using conventional equipment in the art, such as a planetary extruder-spheronizer, a screw extruder-granulator, a spray granulator, etc. The blending and granulation process is carried out using conventional means in the art, and the present invention has no special requirements.

[0026] The present invention also provides a phosphoric acid-modified aluminum-based lithium adsorbent prepared in step (2) of the above method, wherein the phosphoric acid-modified aluminum-based lithium adsorbent is one or more of spherical, ellipsoidal, and rod-shaped particles, with a particle size of 0.3 to 5 mm, preferably 0.4 to 2 mm, and a specific surface area of ​​5 to 50 m 2 / g, the average pore diameter is 1 to 30 μm, and the porosity is 25 to 75%.

[0027] The prepared phosphoric acid-modified aluminum-based lithium adsorbent has an adsorption capacity of 5 to 15 g / L in terms of lithium element. After continuous operation for 6 months, the adsorption performance decay is less than 2%, and the adsorbent dissolution loss is less than 1%.

[0028] The present invention also provides a method for preparing battery-grade lithium carbonate and co-producing potassium chloride from carbonate-type salt lake brine using the above-mentioned phosphoric acid-modified aluminum-based lithium adsorbent, the steps comprising:

[0029] 1) Passing carbonate salt lake brine into a phosphoric acid-modified aluminum-lithium adsorbent, the effluent is the adsorption tail liquid, and desorption is performed after the phosphoric acid-modified aluminum-lithium adsorbent is saturated to obtain an adsorbent desorption liquid;

[0030] 2) The adsorbent desorption liquid of step 1) is sequentially refined by removing magnesium, removing boron, and removing silicon to obtain a refined adsorbent desorption liquid, which is then sequentially concentrated by reverse osmosis and concentrated by evaporation to obtain a lithium precipitation solution;

[0031] 3) mixing the lithium precipitation solution of step 2) with a sodium carbonate solution to precipitate lithium, and then washing and drying to obtain battery-grade lithium carbonate;

[0032] 4) The adsorption tail liquid of step 1) is treated with a nanofiltration membrane to obtain nanofiltration water, which is then evaporated, concentrated, cooled and crystallized to obtain potassium chloride.

[0033] In step 1) of the method of the present invention, the carbonate salt lake brine comprises: 0.5-2.5 g / L of lithium ions, 50-120 g / L of sodium ions, 10-40 g / L of potassium ions, 0.01-1 g / L of magnesium ions, 1-50 g / L of sulfate, 5-50 g / L of carbonate, 0.01-1 g / L of silicon, and 0.1-5 g / L of boron.

[0034] It should be noted that carbonate salt lake brine also contains chloride ions, the concentration of which has no significant effect on the process of the present invention and is not an indicator of concern in the present invention; the salt lake brine must be pretreated with a medium filter or a microfiltration membrane filter with a filtration accuracy of 1 to 10 μm before use in step 1) to remove suspended particulate matter in the brine.

[0035] In step 1) of the method of the present invention, the carbonate salt lake brine is passed through the phosphoric acid-modified aluminum-based lithium adsorbent at a flow rate of 2 to 10 BV / h and a temperature of 15 to 40° C.

[0036] The lithium extraction process of the carbonate salt lake brine passing through the phosphoric acid-modified aluminum-based lithium adsorbent is carried out in a fixed bed or continuous ion exchange system, preferably a continuous ion exchange system.

[0037] In step 1) of the method of the present invention, the adsorption tail liquid comprises: lithium ions ≤ 0.1 g / L, sodium ions 49-118 g / L, potassium ions 10-39 g / L, magnesium ions 0.01-1 g / L, sulfate ions 1-50 g / L, carbonate ions 5-50 g / L, silicon ions 0.005-0.5 g / L, and boron ions 0.1-5 g / L.

[0038] In step 1) of the present method, after the phosphoric acid-modified aluminum-based lithium adsorbent reaches saturation (lithium ion concentration in the adsorption tail liquid > 0.1 g / L), water desorption is performed. Desorption can be performed using conventional methods in the art and is not particularly required by the present invention. For example, the specific desorption conditions employed in some examples of the present invention include a flow rate of 1 to 5 BV / h, a desorption time of 1 to 5 hours, and a desorption temperature of 15 to 50°C, preferably 20 to 45°C.

[0039] In step 1) of the method of the present invention, the adsorbent desorption liquid comprises: 0.3-3 g / L of lithium ions, 0.5-5 g / L of sodium ions, 0.1-1 g / L of potassium ions, 1-10 mg / L of magnesium ions, 1-20 mg / L of sulfate, 1-10 mg / L of carbonate, 10-50 mg / L of silicon, and 10-50 mg / L of boron.

[0040] In step 2) of the method of the present invention, the magnesium removal refining, boron removal refining, and silicon removal refining are performed by sequentially passing the adsorbent desorption liquid through a calcium magnesium chelate resin, a boron chelate resin, and a strong base anion exchange resin for adsorption, with a flow rate of 5 to 20 BV / h and a temperature of 15 to 30° C. during adsorption;

[0041] Preferably, the calcium magnesium chelate resin is Wanhua Chemical One or more of WPA-610 / 611, Zhengguang D860 / D851;

[0042] Preferably, the boron chelate resin is Wanhua Chemical One or more of WPA-620, Zhengguang D870B, and Lanxiao LSC-800;

[0043] Preferably, the strong base cation exchange resin is a 201×4 gel-type strong base anion exchange resin.

[0044] In step 2) of the method of the present invention, the refined adsorbent desorption liquid comprises: 0.3-3 g / L of lithium ions, 0.5-5 g / L of sodium ions, 0.1-1 g / L of potassium ions, ≤0.1 mg / L of magnesium ions, 1-20 mg / L of sulfate, 1-10 mg / L of carbonate, ≤1 mg / L of silicon, and ≤1 mg / L of boron.

[0045] In step 2) of the method of the present invention, the reverse osmosis concentration is to process the refined adsorbent desorption liquid through a reverse osmosis membrane to obtain reverse osmosis concentrated water, and the operating pressure of the reverse osmosis concentration is 1-5 MPaG and the temperature is 15-30°C;

[0046] Preferably, the reverse osmosis concentration multiple is 5 to 15;

[0047] Preferably, the reverse osmosis membrane is Wanhua Chemical SW or Dupont FilmTec TM SW30, LG Chem NanoH2O TM One or more of SW400;

[0048] Preferably, the reverse osmosis membrane assembly is configured as one or more of one stage and one section, one stage and two sections, or one stage and three sections;

[0049] The reverse osmosis water produced in the reverse osmosis concentration step can be recovered for desorption of the front-end adsorbent.

[0050] In step 2) of the method of the present invention, the evaporation concentration is to process the reverse osmosis concentrated water through an MVR evaporator or a multiple-effect evaporator to obtain a lithium precipitation solution;

[0051] Preferably, the evaporation concentration multiple is 2 to 7 times; the evaporation concentration is a conventional operation in this field, and the present invention has no special requirements on the specific operation method and conditions.

[0052] The lithium precipitation solution comprises: 20-30 g / L of lithium ions, 10-50 g / L of sodium ions, 5-10 g / L of potassium ions, ≤1 mg / L of magnesium ions, ≤0.2 g / L of sulfate, ≤0.1 g / L of carbonate, ≤10 mg / L of silicon, and ≤10 mg / L of boron.

[0053] In step 3) of the method of the present invention, the sodium carbonate solution is an aqueous solution with a concentration of 20 to 25 wt%, wherein the calcium ion concentration is ≤1 mg / L and the silicon element concentration is ≤5 mg / L;

[0054] Preferably, the sodium carbonate solution is a refined sodium carbonate solution to reduce the calcium ions and silicon impurities in the solution wrapped by lithium carbonate crystals during lithium precipitation, so that the quality of lithium carbonate reaches battery grade. The refining process can be carried out by conventional means in the art, and there are no special requirements. The concentrations of calcium and silicon elements can be reduced to meet the requirements of the present invention. For example, the industrial-grade sodium carbonate solution can be refined by sequentially passing through a calcium-magnesium chelate resin and a strong base anion exchange resin;

[0055] Among them, the calcium magnesium chelate resin is preferably Wanhua Chemical One or more of WPA-610 / 611, Zhengguang D860 / D851; the strong base cation exchange resin is preferably a 201×4 gel-type strong base anion exchange resin.

[0056] In step 3) of the method of the present invention, the method of mixing the lithium precipitation solution with the sodium carbonate solution to precipitate lithium is to dropwise add the lithium precipitation solution into the sodium carbonate solution under stirring to carry out the lithium precipitation reaction;

[0057] Wherein, preferably, the volume ratio of the lithium precipitation solution to the sodium carbonate solution is 1:1.1 to 1:1.3;

[0058] Preferably, the stirring speed is 100 to 300 rpm;

[0059] Preferably, the lithium precipitation solution is added dropwise for 2 to 5 hours;

[0060] The lithium precipitation reaction is carried out at a temperature of 80 to 95° C. and for a time of 4 to 6 hours, which includes the time for adding the lithium precipitation solution.

[0061] In step 3) of the method of the present invention, the washing and drying are conventional operations in the art. After the drying, a crushing step is also included to obtain an adsorbent product with a suitable particle size. The washing, drying and crushing steps can be carried out using conventional methods in the art. The present invention has no special requirements. The mother liquor and washing water after lithium precipitation can be recycled to improve the lithium recovery rate.

[0062] In step 4) of the method of the present invention, the nanofiltration membrane is required to have a rejection rate of ≥90% for magnesium ions, sulfate, carbonate and boron in carbonate salt lake brine, preferably Wanhua Chemical HP-300, Suez DK, Dupont FilmTec TM One or more of NF245;

[0063] Preferably, the nanofiltration membrane assembly is configured as one or more of one stage and one section, one stage and two sections, or two stages and one section;

[0064] Preferably, the operating pressure of the nanofiltration membrane treatment is 0.5-2 MPaG and the temperature is 15-30°C.

[0065] In step 4) of the method of the present invention, the nanofiltration produced water comprises: lithium ions ≤ 0.08 g / L, sodium ions 40-95 g / L, potassium ions 8-35 g / L, magnesium ions ≤ 50 mg / L, sulfate ions 0.05-2.5 g / L, carbonate ions 0.25-2.5 g / L, silicon ions ≤ 25 mg / L, and boron ions 5-250 mg / L;

[0066] The concentrated nanofiltration water removed by the nanofiltration membrane treatment is recovered and returned to the salt lake.

[0067] In step 4) of the method of the present invention, the evaporation concentration and cooling crystallization are conventional operations in the art and are not particularly required by the present invention. For example, the evaporation concentration can adopt conventional equipment in the art, such as an MVR evaporator, a multiple-effect evaporator, etc., and the evaporation concentration multiple is preferably 2 to 5; the cooling crystallization can adopt conventional equipment in the art, such as a DTB crystallizer, etc.

[0068] The indicators of the battery-grade lithium carbonate prepared by the method of the present invention are shown in Table 1, which meets the standard of "Battery-Grade Lithium Carbonate" (YS / T582-2013), and the lithium element extraction yield can be as high as 85-90%.

[0069] Table 1 Lithium carbonate index prepared by the method of the present invention

[0070]

[0071]

[0072] The indicators of potassium chloride produced as a by-product of the method of the present invention are shown in Table 2, which meets the excellent standard of "Industrial Potassium Chloride" (GB / T 7118-2008), and the potassium recovery rate is 75-80%.

[0073] Table 2 Potassium chloride index prepared by the method of the present invention

[0074]

[0075]

[0076] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0077] (1) The phosphate groups in the phosphate-modified aluminum-based lithium adsorbent protect the active ingredients in the adsorbent from the influence of carbonate ions through electrostatic interaction and space occupancy effect, solving the problem that traditional aluminum-based lithium adsorbents are easily poisoned and deactivated in carbonate salt lakes. It can be directly applied to the lithium extraction process of carbonate salt lakes and has the characteristics of long service life and long-term stable performance.

[0078] (2) The lithium extraction process makes full use of brine resources. Through the coupling of adsorbents, separation membranes and ion exchange resins, the interference of impurity ions in the brine on the purity of lithium carbonate products is reduced. Battery-grade lithium carbonate can be directly produced while industrial-grade potassium chloride is co-produced. It has the advantages of high degree of automation and low construction and production costs. It is particularly suitable for lithium extraction from carbonate salt lake brine in Tibet and other regions. DETAILED DESCRIPTION

[0079] The present invention will be further described below through specific examples. The examples of the present invention are only for illustration of the present invention and do not limit the scope of the present invention.

[0080] The sources of the main raw materials used in the examples and comparative examples of the present invention are shown in Table 1. Unless otherwise specified, the remaining reagents and raw materials are all common commercially available products:

[0081] Table 1 Source of raw materials

[0082] Raw material name Specification source sulfuric acid Industrial grade Wanhua Chemical hydrochloric acid Industrial grade Wanhua Chemical polystyrene Industrial grade Chimei Ethylene dichloride AR Aladdin Anhydrous ferric chloride AR Aladdin Phosphorus trichloride AR Aladdin

[0083] Aluminum-based lithium adsorbent inorganic powder (LiCl·mAl(OH)3·nH2O): prepared according to the method disclosed by Wu Zhijian et al. in "Mechanism of Lithium Adsorption from Brine by Aluminum Hydroxide-Based Lithium Adsorbents." Key performance test methods and instrumentation used in the examples of the present invention:

[0084] The ratio of the phosphoric acid-substituted polystyrene segments in the phosphoric acid-modified polymer was measured by X-ray fluorescence spectrometry (PANalytical AxiosmAX).

[0085] The ion concentrations were determined by inductively coupled plasma optical emission spectrometry (Agilent 720-OES) and ion chromatograph (Metronomic 881).

[0086] The present invention is described in more detail by the following examples, which, however, are not intended to limit the present invention.

[0087] Example 1

[0088] Preparation of phosphoric acid modified aluminum lithium adsorbent, the steps are:

[0089] (1) Polystyrene (styrene chain molar content 100%, Mn = 100000) was dissolved in dichloroethane (mass ratio of polystyrene / dichloroethane = 1:50), anhydrous ferric chloride (mass ratio of anhydrous ferric chloride / dichloroethane = 1:100) and phosphorus trichloride (mass ratio of phosphorus trichloride / polystyrene = 1:10) were added, and phosphating reaction was carried out at 25° C. for 4 h. After the reaction, ethanol replacement (alcohol washing) was performed, 4 wt % sodium hydroxide aqueous solution, 4 wt % hydrochloric acid, water washing, and drying were performed to obtain phosphoric acid-modified polystyrene, wherein the molar ratio of phosphoric acid-substituted polystyrene chain segments was 50%.

[0090] (2) Phosphoric acid-modified polystyrene and inorganic powder of aluminum-based lithium adsorbent (LiCl·2Al(OH)3·3H2O) with a particle size of 10 μm were added into a screw extruder-pelletizer at a mass ratio of 1:4 and blended to obtain rod-shaped particles with a particle size of 1 mm, namely phosphoric acid-modified aluminum-based lithium adsorbent with a specific surface area of ​​40 m 2 / g, the average pore diameter is 20μm, and the porosity is 65%.

[0091] The above-mentioned phosphoric acid-modified aluminum-based lithium adsorbent is used to prepare battery-grade lithium carbonate and potassium chloride from carbonate-type salt lake brine, and the steps are as follows:

[0092] 1) Winter brine from the northern lake of Zabuye Salt Lake was used, and the ion concentrations in the brine were 1.6 g / L lithium ion, 90 g / L sodium ion, 30 g / L potassium ion, 0.02 g / L magnesium ion, 6 g / L sulfate, 13 g / L carbonate, 0.5 g / L silicon, and 1.3 g / L boron.

[0093] After pretreatment with a 1 μm microfiltration membrane filter, the brine was passed through the above-mentioned phosphoric acid-modified aluminum-based lithium adsorbent prepared in this example. The adsorption and lithium extraction process was carried out in a continuous desorption system. The adsorption conditions were a flow rate of 5 BV / h and a temperature of 20°C. The effluent was the adsorption tail liquid. After saturation, it was desorbed with water at a desorption flow rate of 2 BV / h, a desorption temperature of 45°C, and a desorption time of 2 h to obtain an adsorbent desorption liquid.

[0094] The ion concentrations in the adsorbent desorption solution are 0.7 g / L lithium ion, 3 g / L sodium ion, 0.6 g / L potassium ion, 5 mg / L magnesium ion, 10 mg / L sulfate, 5 mg / L carbonate, 20 mg / L silicon, and 10 mg / L boron.

[0095] The ion concentrations of the adsorption tail liquid are 0.05 g / L lithium ion, 77 g / L sodium ion, 27 g / L potassium ion, 0.02 g / L magnesium ion, 6 g / L sulfate, 13 g / L carbonate, 0.25 g / L silicon, and 1.3 g / L boron.

[0096] The phosphoric acid-modified aluminum-based lithium adsorbent has an adsorption capacity of 10 g / L in terms of lithium element. After continuous operation for 6 months, the adsorption performance decays by 1% and the adsorbent dissolution loss is 0.5%.

[0097] 2) The adsorbent desorption liquid flows through Wanhua Chemical in sequence WPA-610 calcium magnesium chelate resin for magnesium removal, Wanhua Chemical Boron was removed using WPA-620 boron chelate resin and silicon was removed using 201×4 gel-type strong base anion exchange resin to obtain a refined adsorbent desorption solution. Adsorption conditions were a flow rate of 5 BV / h and a temperature of 20°C. The ion concentrations in the refined adsorbent desorption solution were 0.7 g / L lithium, 3 g / L sodium, 0.6 g / L potassium, no magnesium detected, 10 mg / L sulfate, 5 mg / L carbonate, 0.5 mg / L silicon, and 0.5 mg / L boron.

[0098] The refined adsorbent desorption liquid enters the reverse osmosis concentration process to obtain reverse osmosis concentrated water; the reverse osmosis concentration operating pressure is 5MPaG, the temperature is 20℃; the reverse osmosis concentration factor is 10; the reverse osmosis membrane is selected from Wanhua Chemical SW, the configuration of the membrane assembly is one stage, and the reverse osmosis water produced by reverse osmosis concentration and removal is recovered as water for adsorbent desorption in step 1);

[0099] The reverse osmosis concentrated water is evaporated and concentrated by MVR evaporator at a concentration factor of 4 to obtain lithium precipitation solution;

[0100] The ion concentrations in the lithium precipitation solution are 30 g / L lithium ions, 40 g / L sodium ions, 10 g / L potassium ions, 0.5 mg / L magnesium ions, 0.1 g / L sulfate, 0.05 g / L carbonate, 5 mg / L silicon, and 5 mg / L boron.

[0101] 3) The industrial grade sodium carbonate aqueous solution is passed through Wanhua Chemical WPA-610 calcium magnesium chelate resin and 201×4 type gel-type strong base anion exchange resin are used to obtain a 25wt% purified sodium carbonate aqueous solution, wherein the calcium ion concentration in the purified sodium carbonate solution is 1mg / L and the silicon element concentration is 5mg / L;

[0102] The lithium precipitate solution was dropped into the stirred refined sodium carbonate aqueous solution, the volume ratio of the lithium precipitate solution to the refined sodium carbonate solution was 1:1.2, the lithium precipitate solution was added dropwise for 5 hours, and after the lithium precipitate solution was added dropwise, the precipitation was continued for 1 hour with the stirring speed of 300 rpm and the lithium precipitation temperature of 95°C. Battery-grade lithium carbonate was obtained after washing, drying and crushing. The mother liquor and washing water after lithium precipitation were recovered and reused in the lithium precipitation process.

[0103] 4) The adsorption tail liquid is treated with nanofiltration membrane to obtain nanofiltration water. The nanofiltration membrane is selected from Wanhua Chemical The HP-300 operates at a pressure of 2 MPaG and a temperature of 20°C. The membrane components are configured in a single-stage configuration. The ion concentrations of the nanofiltration product water are 0.04 g / L lithium, 62 g / L sodium, 22 g / L potassium, 1 mg / L magnesium, 0.3 g / L sulfate, 0.6 g / L carbonate, 10 mg / L silicon, and 60 mg / L boron. The concentrated water removed by the nanofiltration membrane is recovered and returned to the salt lake.

[0104] The nanofiltration water is evaporated and concentrated in an MVR evaporator with a concentration multiple of 3, and then cooled and crystallized in a DTB crystallizer to obtain industrial-grade potassium chloride.

[0105] The indicators of battery-grade lithium carbonate are shown in Table 3, which meets the standard of "Battery-Grade Lithium Carbonate" (YS / T 582-2013), and the lithium element extraction yield is 90%.

[0106] The various indicators of potassium chloride are shown in Table 4, which meet the excellent standard of "Industrial Potassium Chloride" (GB / T 7118-2008), and the potassium recovery rate is 75%.

[0107] Example 2

[0108] Preparation of phosphoric acid modified aluminum lithium adsorbent, the steps are:

[0109] (1) A mixture of chlorinated polystyrene and brominated polystyrene (the mass ratio of the two is 1:1, the molar content of styrene segments in the mixture is 100%, and the Mn of both polymers is 300,000) is dissolved in dichloropropane (mass ratio of chlorinated polystyrene + brominated polystyrene / dichloropropane = 1:10), anhydrous aluminum chloride (mass ratio of anhydrous aluminum chloride / dichloropropane = 1:1000) and phosphorus trichloride (mass ratio of phosphorus trichloride / chlorinated polystyrene + brominated polystyrene = 1:1) are added, and the mixture is subjected to phosphation reaction at 15°C for 8 hours. After the reaction, the mixture is replaced with ethanol (alcohol washing), washed with 4 wt% sodium hydroxide aqueous solution, 4 wt% hydrochloric acid, washed with water, and dried to obtain phosphoric acid-modified polystyrene, wherein the molar ratio of phosphoric acid-substituted polystyrene segments is 25%.

[0110] (2) Phosphoric acid-modified polystyrene and inorganic powder of aluminum-based lithium adsorbent (LiCl·3Al(OH)3·4H2O) with a particle size of 0.5 μm were added to a planetary extruder-spheronizer in a mass ratio of 1:5 and blended to obtain spherical particles with a particle size of 5 mm, namely phosphoric acid-modified aluminum-based lithium adsorbent with a specific surface area of ​​5 m 2 / g, the average pore diameter is 30μm, and the porosity is 75%.

[0111] The above-mentioned phosphoric acid-modified aluminum-based lithium adsorbent is used to prepare battery-grade lithium carbonate and potassium chloride from carbonate-type salt lake brine, and the steps are as follows:

[0112] 1) Summer brine from the northern lake of Zabuye Salt Lake was used, and the ion concentrations in the brine were 0.5 g / L lithium ion, 120 g / L sodium ion, 10 g / L potassium ion, 1 g / L magnesium ion, 1 g / L sulfate, 50 g / L carbonate, 0.01 g / L silicon, and 5 g / L boron.

[0113] After pretreatment with a 10 μm medium filter, the brine was passed through the above-mentioned phosphoric acid-modified aluminum-based lithium adsorbent prepared in this example. The adsorption and lithium extraction process was carried out in a fixed bed under the adsorption conditions of a flow rate of 2 BV / h and a temperature of 40°C. The effluent was the adsorption tail liquid. After saturation, it was desorbed with water at a desorption flow rate of 1 BV / h, a desorption temperature of 15°C, and a desorption time of 5 h to obtain an adsorbent desorption liquid.

[0114] The ion concentrations in the adsorbent desorption solution are 0.3 g / L lithium ion, 5 g / L sodium ion, 0.1 g / L potassium ion, 10 mg / L magnesium ion, 1 mg / L sulfate, 10 mg / L carbonate, 10 mg / L silicon, and 50 mg / L boron.

[0115] The ion concentrations of the adsorption tail liquid are 0.05 g / L lithium ion, 118 g / L sodium ion, 10 g / L potassium ion, 1 g / L magnesium ion, 1 g / L sulfate, 50 g / L carbonate, 0.005 g / L silicon, and 5 g / L boron.

[0116] The phosphoric acid-modified aluminum-based lithium adsorbent has an adsorption capacity of 5 g / L in terms of lithium element. After continuous operation for 6 months, the adsorption performance decayed by 2% and the adsorbent dissolution loss was 0.6%.

[0117] 2) The adsorbent desorption liquid flows through Wanhua Chemical in sequence Magnesium was removed using WPA-611 calcium-magnesium chelate resin, boron was removed using Zhengguang D870B boron chelate resin, and silicon was removed using 201×4 gel-type strong base anion exchange resin. The adsorption conditions were a flow rate of 20 BV / h and a temperature of 30°C. The ion concentrations in the refined adsorbent desorption solution were 0.3 g / L lithium, 5 g / L sodium, 0.1 g / L potassium, 0.1 mg / L magnesium, 1 mg / L sulfate, 10 mg / L carbonate, no silicon detected, and 1 mg / L boron.

[0118] The refined adsorbent desorption liquid enters the reverse osmosis concentration process to obtain reverse osmosis concentrated water; the reverse osmosis concentration operating pressure is 1MPaG, the temperature is 15℃; the reverse osmosis concentration factor is 15; the reverse osmosis membrane is Dupont FilmTec TM SW30 and LG ChemNanoH2O TM SW400, the membrane assembly is configured as a one-stage two-stage process, and the reverse osmosis product water removed by reverse osmosis concentration is recovered as the water for adsorbent desorption in step 1);

[0119] The reverse osmosis concentrated water is evaporated and concentrated by a multi-effect evaporator at a concentration factor of 7 to obtain a lithium precipitation solution;

[0120] The ion concentrations in the lithium precipitation solution are 20 g / L lithium ions, 50 g / L sodium ions, 5 g / L potassium ions, 1 mg / L magnesium ions, 10 mg / L sulfate, 0.1 g / L carbonate, 0.1 mg / L silicon, and 10 mg / L boron.

[0121] 3) The industrial grade sodium carbonate aqueous solution is passed through Wanhua Chemical WPA-611 calcium magnesium chelate resin and 201×4 type gel-type strong base anion exchange resin are used to obtain a 20wt% purified sodium carbonate aqueous solution, wherein the calcium ion concentration in the purified sodium carbonate solution is 0.5mg / L and the silicon element concentration is 1mg / L;

[0122] The lithium precipitate solution was dropped into the stirred refined sodium carbonate aqueous solution, the volume ratio of the lithium precipitate solution to the refined sodium carbonate solution was 1:1.1, the lithium precipitate solution was added for 2 hours, and after the lithium precipitate solution was added, the precipitation was continued for 2 hours with the stirring speed of 100 rpm and the lithium precipitation temperature of 80°C. Battery-grade lithium carbonate was obtained after washing, drying and crushing. The mother liquor and washing water after lithium precipitation were recovered and reused in the lithium precipitation process.

[0123] 4) The adsorption tail liquid is treated with a nanofiltration membrane to produce nanofiltration product water. The nanofiltration membrane selected is Suez DK, with an operating pressure of 0.5 MPaG and a temperature of 30°C. The membrane assembly is configured as a one-stage, two-stage process. The ion concentrations in the nanofiltration product water are 0.01 g / L lithium ion, 95 g / L sodium ion, 8 g / L potassium ion, 50 mg / L magnesium ion, 0.05 g / L sulfate, 2.5 g / L carbonate, 1 mg / L silicon, and 250 mg / L boron. The nanofiltration concentrate removed by the nanofiltration membrane is recovered and returned to the salt lake.

[0124] The nanofiltration water is evaporated and concentrated in a multi-effect evaporator with a concentration factor of 5, and then cooled and crystallized in a DTB crystallizer to obtain industrial-grade potassium chloride.

[0125] The indicators of battery-grade lithium carbonate are shown in Table 3, which meets the standard of "Battery-Grade Lithium Carbonate" (YS / T 582-2013), and the lithium element extraction yield is 85%.

[0126] The various indicators of potassium chloride are shown in Table 4, which meet the excellent standard of "Industrial Potassium Chloride" (GB / T 7118-2008), and the potassium recovery rate is 80%.

[0127] Example 3

[0128] Preparation of phosphoric acid modified aluminum lithium adsorbent, the steps are:

[0129] (1) A mixture of styrene-methyl methacrylate copolymer, styrene-isoprene copolymer and acrylonitrile-butadiene-styrene copolymer (mass ratio of the three is 1:1:1, the molar content of styrene segments in the mixture is 50%, and the Mn of the three polymers is 50,000) is dissolved in a mixture of dichloroethane and nitrobenzene (volume ratio 1:1) (mass ratio of styrene-methyl methacrylate copolymer + styrene-isoprene copolymer + acrylonitrile-butadiene-styrene copolymer / dichloroethane + nitrobenzene = 1:100), and a mixture of 1:1:1 is added. A mixture of anhydrous aluminum chloride and anhydrous zinc chloride (mass ratio of anhydrous aluminum chloride + anhydrous zinc chloride / dichloroethane + nitrobenzene = 1:500) and phosphorus trichloride (mass ratio of phosphorus trichloride / styrene-methyl methacrylate copolymer + styrene-isoprene copolymer + acrylonitrile-butadiene-styrene copolymer = 1:20) is subjected to phosphating reaction at 45° C. for 1 hour. After the reaction, ethanol replacement (alcohol washing) is performed, followed by addition of a 4wt% aqueous sodium hydroxide solution, 4wt% hydrochloric acid, water washing, and drying to obtain phosphoric acid-modified polystyrene, wherein the proportion of phosphoric acid-substituted polystyrene chain segments is 30%.

[0130] (2) Phosphoric acid-modified polystyrene and inorganic powder of aluminum-based lithium adsorbent (LiCl·2Al(OH)3·2H2O) with a particle size of 50 μm were added to a spray granulator at a mass ratio of 2:1 and blended to obtain spherical and ellipsoidal particles with a particle size of 0.3 mm, namely phosphoric acid-modified aluminum-based lithium adsorbent with a specific surface area of ​​50 m 2 / g, the average pore diameter is 1 μm, and the porosity is 25%.

[0131] The above-mentioned phosphoric acid-modified aluminum-based lithium adsorbent is used to prepare battery-grade lithium carbonate and potassium chloride from carbonate-type salt lake brine, and the steps are as follows:

[0132] 1) Winter brine from the southern lake of Zabuye Salt Lake was used, and the ion concentrations in the brine were 2.5 g / L lithium ion, 50 g / L sodium ion, 40 g / L potassium ion, 0.01 g / L magnesium ion, 50 g / L sulfate, 5 g / L carbonate, 1 g / L silicon, and 0.1 g / L boron.

[0133] After pretreatment with a 1 μm microfiltration membrane filter, the brine was passed through the above-mentioned phosphoric acid-modified aluminum-based lithium adsorbent prepared in this example. The adsorption and lithium extraction process was carried out in a continuous desorption system. The adsorption conditions were a flow rate of 10 BV / h and a temperature of 15°C. The effluent was the adsorption tail liquid. After saturation, it was desorbed with water at a desorption flow rate of 5 BV / h, a desorption temperature of 50°C, and a desorption time of 1 hour to obtain an adsorbent desorption liquid.

[0134] The ion concentrations in the adsorbent desorption solution are 3 g / L lithium ion, 0.5 g / L sodium ion, 1 g / L potassium ion, 1 mg / L magnesium ion, 20 mg / L sulfate, 1 mg / L carbonate, 50 mg / L silicon, and 10 mg / L boron.

[0135] The ion concentrations of the adsorption tail liquid are 0.1 g / L lithium ion, 49 g / L sodium ion, 39 g / L potassium ion, 0.01 g / L magnesium ion, 50 g / L sulfate, 5 g / L carbonate, 0.5 g / L silicon, and 0.1 g / L boron.

[0136] The phosphoric acid-modified aluminum-based lithium adsorbent has an adsorption capacity of 15 g / L in terms of lithium element. After continuous operation for 6 months, the adsorption performance decayed by 0.5% and the adsorbent dissolution loss was 1%.

[0137] 2) The adsorbent desorption liquid was sequentially passed through Zhengguang D860 and D851 calcium-magnesium chelate resins (volume ratio of the two resins was 1:1) to remove magnesium, Zhengguang D870B and Lanxiao LSC-800 boron chelate resins (volume ratio of the two resins was 1:1) to remove boron, and 201×4 gel-type strong base anion exchange resin to remove silicon to obtain a refined adsorbent desorption liquid. Adsorption conditions were a flow rate of 10 BV / h and a temperature of 15°C. The ion concentrations in the refined adsorbent desorption liquid were 3 g / L lithium, 0.5 g / L sodium, 1 g / L potassium, undetectable magnesium, 20 mg / L sulfate, 1 mg / L carbonate, 1 mg / L silicon, and undetectable boron.

[0138] The refined adsorbent desorption liquid enters the reverse osmosis concentration process to obtain reverse osmosis concentrated water; the reverse osmosis concentration operating pressure is 2MPaG, the temperature is 30℃; the reverse osmosis concentration factor is 5; the reverse osmosis membrane is Dupont FilmTec TM SW30, the configuration of the membrane module is one stage two sections or one stage three sections, and the reverse osmosis water produced by reverse osmosis concentration and removal is recovered as water for adsorbent desorption in step 1);

[0139] The reverse osmosis concentrated water is evaporated and concentrated by MVR evaporator at a concentration factor of 2 to obtain lithium precipitation solution;

[0140] The ion concentrations in the lithium precipitation solution are 30 g / L lithium ions, 10 g / L sodium ions, 10 g / L potassium ions, 0.5 mg / L magnesium ions, 0.2 g / L sulfate, 0.01 g / L carbonate, 10 mg / L silicon, and 1 mg / L boron.

[0141] 3) passing an industrial-grade aqueous sodium carbonate solution through Zhengguang D860 and D851 calcium-magnesium chelate resins (the two resins have a volume ratio of 1:1) and a 201×4 gel-type strong base anion exchange resin to obtain a 25 wt % refined aqueous sodium carbonate solution having a calcium ion concentration of 0.1 mg / L and a silicon element concentration of 1 mg / L;

[0142] The lithium precipitate solution was dropped into the stirred refined sodium carbonate aqueous solution, the volume ratio of the lithium precipitate solution to the refined sodium carbonate solution was 1:1.3, the lithium precipitate solution was added for 2 hours, and after the lithium precipitate solution was added, the precipitation was continued for 3 hours with the stirring speed of 200 rpm and the lithium precipitation temperature of 95°C. Battery-grade lithium carbonate was obtained after washing, drying and crushing. The mother liquor and washing water after lithium precipitation were recovered and reused in the lithium precipitation process.

[0143] 4) The adsorption tail liquid is treated with nanofiltration membrane to obtain nanofiltration water. The nanofiltration membranes used are Suez DK and Dupont FilmTec TM The NF245 operates at an operating pressure of 2 MPaG and a temperature of 15°C. The membrane modules are configured as either a one-stage, two-stage configuration or a two-stage, one-stage configuration. The ion concentrations of the nanofiltration product water are 0.08 g / L lithium, 40 g / L sodium, 35 g / L potassium, 5 mg / L magnesium, 2.5 g / L sulfate, 0.25 g / L carbonate, 25 mg / L silicon, and 5 mg / L boron. The concentrated water removed by the nanofiltration membrane is recovered and returned to the salt lake.

[0144] The nanofiltration water is evaporated and concentrated in an MVR evaporator with a concentration factor of 2, and then cooled and crystallized in a DTB crystallizer to obtain industrial-grade potassium chloride.

[0145] The indicators of battery-grade lithium carbonate are shown in Table 3, which meets the standard of "Battery-Grade Lithium Carbonate" (YS / T 582-2013), and the lithium extraction yield is 86%.

[0146] The various indicators of potassium chloride are shown in Table 4, which meet the excellent standard of "Industrial Potassium Chloride" (GB / T 7118-2008), and the potassium recovery rate is 77%.

[0147] Comparative Example 1

[0148] A phosphoric acid-modified aluminum-based lithium adsorbent was prepared according to the method of Example 1, except that polystyrene was replaced by an equal mass of polymethacrylate (no styrene segment, Mn = 150,000, and the molar ratio of phosphoric acid replacing polymethacrylate segment was 25%). Other operations and conditions remained unchanged to obtain a phosphoric acid-modified aluminum-based lithium adsorbent. Rod-shaped particles with a particle size of 1 mm and a specific surface area of ​​0.5 m 2 / g, the average pore diameter is 100μm, and the porosity is 5%.

[0149] The brine described in Example 1 was treated using the above-mentioned phosphoric acid-modified aluminum-based lithium adsorbent according to the process scheme described in Example 1. The brine was sampled and analyzed after 6 hours of operation. The various indicators of lithium carbonate are shown in Table 3. The lithium carbonate content, Na content, and K content did not meet the "Battery Grade Lithium Carbonate" (YS / T 582-2013) standard, and the lithium element extraction yield was 61%.

[0150] The various indicators of potassium chloride are shown in Table 4. The potassium chloride content, sodium chloride content, total calcium and magnesium ion content, and sulfate content did not meet the excellent standard of "Industrial Potassium Chloride" (GB / T 7118-2008), and the potassium recovery rate was 52%.

[0151] The initial adsorption capacity of the adsorbent was 1.5 g / L. After running three adsorption-desorption cycles (a total of 18 h), it was poisoned and inactivated, and the adsorption capacity decreased to 0.1 g / L.

[0152] Comparative Example 2

[0153] The sulfonic acid-modified aluminum-based lithium adsorbent was prepared by referring to the method of Example 1, except that phosphorus trichloride was replaced by an equal mass of 98% concentrated sulfuric acid (the ratio of sulfonic acid replacing styrene chain segments was 50%). Other operations and conditions remained unchanged to obtain a sulfonic acid-modified aluminum-based lithium adsorbent. Rod-shaped particles with a particle size of 1 mm and a specific surface area of ​​1 m 2 / g, the average pore diameter is 50μm, and the porosity is 10%.

[0154] The brine described in Example 1 was treated with the sulfonic acid-modified aluminum-based lithium adsorbent according to the process scheme described in Example 1. The brine was sampled and analyzed after 6 hours of operation. The various indicators of lithium carbonate are shown in Table 3. The lithium carbonate content, Na content, Mg content, and K content did not meet the standards of "Battery Grade Lithium Carbonate" (YS / T 582-2013), and the lithium extraction yield was 57%.

[0155] The various indicators of potassium chloride are shown in Table 4. The potassium chloride content, sodium chloride content, total calcium and magnesium ion content, sulfate content, and water-insoluble matter index did not meet the excellent standard of "Industrial Potassium Chloride" (GB / T 7118-2008), and the potassium recovery rate was 58%.

[0156] The initial adsorption capacity of the adsorbent was 2 g / L. After running 5 adsorption-desorption cycles (30 h in total), it was poisoned and inactivated, and the adsorption capacity decreased to 0.2 g / L.

[0157] Comparative Example 3

[0158] The phosphoric acid modified aluminum lithium adsorbent and adsorption process prepared in Example 1 were used to treat the winter brine of the northern lake of Zabuye Salt Lake. The adsorbent desorption liquid was sequentially passed through Wanhua Chemical WPA-610 calcium magnesium chelate resin for magnesium removal, Wanhua Chemical WPA-620 boron chelate resin was deboronized to obtain a refined adsorbent desorption liquid. The ion concentration in the refined adsorbent desorption liquid was 0.7 g / L for lithium ions, 3 g / L for sodium ions, 0.6 g / L for potassium ions, undetectable magnesium ions, 10 mg / L for sulfate, 5 mg / L for carbonate, 20 mg / L for silicon, and 0.5 mg / L for boron. The reverse osmosis and evaporation concentration processes were the same as those in Example 1. The ion concentration in the lithium precipitation liquid was 30 g / L for lithium ions, 40 g / L for sodium ions, 10 g / L for potassium ions, 0.5 mg / L for magnesium ions, 0.1 g / L for sulfate, 0.05 g / L for carbonate, 0.5 g / L for silicon, and 5 mg / L for boron.

[0159] The sodium carbonate refining and lithium precipitation processes were the same as in Example 1. The various indicators of lithium carbonate are shown in Table 3. The lithium carbonate content, Mg content, Ca content, and Si content did not meet the standards of "Battery Grade Lithium Carbonate" (YS / T 582-2013), and the lithium extraction yield was 76%.

[0160] Comparative Example 4

[0161] Referring to Example 1, the phosphoric acid-modified aluminum-based lithium adsorbent prepared in this example was used to prepare battery-grade lithium carbonate and co-produce potassium chloride from carbonate-type salt lake brine. The difference was that the adsorption tail liquid treatment method in step 4) was changed to: the adsorption tail liquid was evaporated and concentrated by an MVR evaporator with a concentration factor of 3, and then cooled and crystallized using a DTB crystallizer to obtain a mixed salt of potassium chloride, potassium carbonate, and potassium sulfate (potassium chloride accounts for 60%). The various indicators of the mixed salt are shown in Table 4. Except for moisture, the other indicators did not meet the excellent grade standard of "Industrial Potassium Chloride" (GB / T 7118-2008), and the potassium recovery rate was 33%.

[0162] Table 3 Lithium carbonate indicators prepared in Examples 1-3 and Comparative Examples 1-3

[0163]

[0164]

[0165] Table 4 Potassium chloride indexes prepared in Examples 1-3 and Comparative Examples 1, 2, and 4

[0166]

Claims

1. A method for preparing a phosphoric acid-modified aluminum-based lithium adsorbent, characterized in that the steps include: (1) dissolving a polymer containing a styrene chain segment in an organic solvent, adding a phosphating catalyst and phosphorus trichloride to carry out a phosphating reaction, and after the reaction is completed, washing with alkali and acid to obtain a phosphoric acid-modified polymer; (2) blending and granulating the phosphoric acid-modified polymer of step (1) with an aluminum-based lithium adsorbent to obtain a phosphoric acid-modified aluminum-based lithium adsorbent; In step (1), the phosphating catalyst is selected from one or more of aluminum chloride, ferric chloride, and zinc chloride; In step (2), the aluminum-based lithium adsorbent is selected from an adsorbent with the general formula LiCl·mAl(OH)3·nH2O, wherein m=2-3 and n=2-4.

2. The preparation method according to claim 1, characterized in that In step (1), the polymer containing styrene chain segments is selected from one or more of polystyrene, polystyrene halide, copolymers of styrene and acrylate monomers, and copolymers of styrene and olefin monomers; The molar content of the styrene chain segments in the polymer containing styrene chain segments is 50 to 100%; The number average molecular weight of the polymer containing styrene chain segments is 50,000 to 300,000.

3. The preparation method according to claim 2, characterized in that The polymer containing styrene chain segments is selected from one or more of polystyrene, chlorinated polystyrene, brominated polystyrene, styrene-methyl methacrylate copolymer, styrene-isoprene copolymer, and acrylonitrile-butadiene-styrene copolymer.

4. The preparation method according to claim 2, characterized in that The molar content of the styrene chain segments in the polymer containing styrene chain segments is 70-100%.

5. The preparation method according to claim 2, characterized in that The number average molecular weight of the polymer containing styrene chain segments is 100,000 to 250,000.

6. The preparation method according to claim 1, characterized in that In step (1), the organic solvent is selected from one or more of dichloroethane, nitrobenzene, and dichloropropane; The mass ratio of the polymer containing styrene chain segments to the organic solvent is 1:10 to 1:100; and / or In step (1), The mass ratio of the phosphating catalyst to the organic solvent is 1:100 to 1:1000; and / or In step (1), the mass ratio of the phosphorus trichloride to the polymer containing styrene chain segments is 1:1 to 1:20; and / or In step (1), the phosphating reaction is carried out at a temperature of 15 to 45° C. and for a time of 1 to 8 hours; and / or In step (1), the molar ratio of the phosphoric acid-substituted polystyrene segments in the phosphoric acid-modified polymer is 25 to 50%.

7. The preparation method according to claim 6, characterized in that The mass ratio of the polymer containing styrene chain segments to the organic solvent is 1:20 to 1:

80.

8. The preparation method according to claim 6, characterized in that The mass ratio of the phosphating catalyst to the organic solvent is 1:200 to 1:

800.

9. The preparation method according to claim 6, characterized in that The mass ratio of the phosphorus trichloride to the polymer containing styrene chain segments is 1:5 to 1:

15.

10. The preparation method according to claim 6, characterized in that The phosphating reaction is carried out at a temperature of 25 to 40° C. and for a time of 2 to 6 hours.

11. The preparation method according to claim 1, characterized in that In step (2), the aluminum-based lithium adsorbent is an inorganic powder with a particle size of 0.5 to 50 μm; and / or In step (2), the mass ratio of the phosphoric acid-modified polymer to the aluminum-based lithium adsorbent is 1:5 to 2:

1.

12. The preparation method according to claim 11, characterized in that The aluminum-based lithium adsorbent is an inorganic powder with a particle size of 1 to 30 μm.

13. The preparation method according to claim 11, characterized in that The mass ratio of the phosphoric acid-modified polymer to the aluminum-based lithium adsorbent is 1:4 to 1:

1.

14. A phosphoric acid-modified aluminum-based lithium adsorbent prepared by the preparation method according to any one of claims 1 to 13, characterized in that: The shape is one or more of spherical, ellipsoidal, and rod-shaped particles; the particle size is 0.3 to 5 mm, and the specific surface area is 5 to 50 m 2 / g, the average pore diameter is 1 to 30 μm, and the porosity is 25 to 75%.

15. The phosphoric acid-modified aluminum-based lithium adsorbent according to claim 14, characterized in that: The particle size is 0.4 to 2 mm.

16. A method for preparing battery-grade lithium carbonate and potassium chloride from carbonate-type salt lake brine using the phosphoric acid-modified aluminum-based lithium adsorbent prepared by the preparation method according to any one of claims 1 to 13 or the phosphoric acid-modified aluminum-based lithium adsorbent according to claim 14 or 15, characterized in that the steps include: 1) carbonate salt lake brine is passed into a phosphoric acid-modified aluminum-lithium adsorbent, the effluent is the adsorption tail liquid, and the phosphoric acid-modified aluminum-lithium adsorbent is desorbed after being saturated to obtain an adsorbent desorption liquid; 2) The adsorbent desorption liquid of step 1) is sequentially refined by removing magnesium, removing boron, and removing silicon to obtain a refined adsorbent desorption liquid, which is then sequentially concentrated by reverse osmosis and concentrated by evaporation to obtain a lithium precipitation solution; 3) mixing the lithium precipitation solution of step 2) with a sodium carbonate solution to precipitate lithium, and then washing and drying to obtain battery-grade lithium carbonate; 4) The adsorption tail liquid of step 1) is treated with a nanofiltration membrane to obtain nanofiltration water, which is then evaporated, concentrated, cooled and crystallized to obtain potassium chloride.

17. The method according to claim 16, characterized in that In step 1), the carbonate salt lake brine comprises: 0.5-2.5 g / L lithium ions, 50-120 g / L sodium ions, 10-40 g / L potassium ions, 0.01-1 g / L magnesium ions, 1-50 g / L sulfate, 5-50 g / L carbonate, 0.01-1 g / L silicon, and 0.1-5 g / L boron; and / or In step 1), the carbonate salt lake brine is passed through the phosphoric acid-modified aluminum-based lithium adsorbent at a flow rate of 2 to 10 BV / h and a temperature of 15 to 40° C. The lithium extraction process of introducing the carbonate salt lake brine into the phosphoric acid-modified aluminum-based lithium adsorbent is carried out in a fixed bed or continuous ion exchange system.

18. The method according to claim 16, characterized in that In step 1), the salt lake brine is pretreated by a medium filter or a microfiltration membrane filter with a filtration accuracy of 1 to 10 μm.

19. The method according to claim 16, wherein In step 2), the magnesium removal refining, boron removal refining, and silicon removal refining are performed by sequentially passing the adsorbent desorption liquid through a calcium magnesium chelate resin, a boron chelate resin, and a strong base anion exchange resin for adsorption, with a flow rate of 5 to 20 BV / h and a temperature of 15 to 30° C. during adsorption; and / or In step 2), the reverse osmosis concentration is to process the refined adsorbent desorption liquid through a reverse osmosis membrane to obtain reverse osmosis concentrated water, and the operating pressure of the reverse osmosis concentration is 1-5 MPaG and the temperature is 15-30° C.; and / or In step 2), the evaporation concentration is to process the reverse osmosis concentrated water through an MVR evaporator or a multiple-effect evaporator to obtain a lithium precipitation solution.

20. The method according to claim 19, characterized in that The calcium magnesium chelate resin is from Wanhua Chemical One or more of WPA-610 / 611, Zhengguang D860 / D851.

21. The method according to claim 19, wherein The boron chelate resin is from Wanhua Chemical One or more of WPA-620, Zhengguang D870B, and Lanxiao LSC-800.

22. The method according to claim 19, wherein The strong base cation exchange resin is a 201×4 gel-type strong base anion exchange resin.

23. The method according to claim 19, wherein The reverse osmosis concentration multiple is 5 to 15.

24. The method according to claim 19, wherein The reverse osmosis membrane is from Wanhua Chemical SW or Dupont FilmTec TM SW30, LG Chem NanoH2O TM One or more of SW400.

25. The method according to claim 19, wherein The configuration of the reverse osmosis membrane assembly is one or more of one stage and one section, one stage and two sections, or one stage and three sections.

26. The method according to claim 19, wherein The evaporation concentration multiple is 2 to 7 times.

27. The method according to claim 16, wherein In step 3), the sodium carbonate solution is an aqueous solution with a concentration of 20-25%, wherein the calcium ion concentration is ≤1 mg / L and the silicon element concentration is ≤5 mg / L; and / or In step 3), the method of mixing the lithium precipitation solution with the sodium carbonate solution to precipitate lithium is to add the lithium precipitation solution dropwise into the sodium carbonate solution under stirring to carry out lithium precipitation reaction; The lithium precipitation reaction is carried out at a temperature of 80 to 95° C. and for a time of 4 to 6 hours, which includes the time for adding the lithium precipitation solution.

28. The method according to claim 27, characterized in that The sodium carbonate solution is a refined sodium carbonate solution, and the refining method is to purify the industrial-grade sodium carbonate solution by sequentially passing it through a calcium-magnesium chelate resin and a strong base anion exchange resin.

29. The method according to claim 28, characterized in that The calcium magnesium chelate resin is from Wanhua Chemical One or more of WPA-610 / 611, Zhengguang D860 / D851.

30. The method according to claim 28, wherein The strong base cation exchange resin is a 201×4 gel-type strong base anion exchange resin.

31. The method according to claim 27, wherein The volume ratio of the lithium precipitation solution to the sodium carbonate solution is 1:1.1 to 1:1.

3.

32. The method according to claim 27, wherein The stirring speed is 100-300 rpm.

33. The method according to claim 27, wherein The lithium precipitation solution is added dropwise for 2 to 5 hours.

34. The method according to claim 16, wherein In step 4), the nanofiltration membrane is required to have a rejection rate of ≥90% for magnesium ions, sulfate, carbonate and boron elements in carbonate salt lake brine.

35. The method according to claim 34, wherein The nanofiltration membrane is Wanhua Chemical HP-300, Suez DK, DupontFilmTec TM One or more of NF245.

36. The method according to claim 34, wherein The nanofiltration membrane assembly is configured in one or more of one stage and one section, one stage and two sections, or two stages and one section.

37. The method according to claim 34, wherein The operating pressure of nanofiltration membrane treatment is 0.5~2MPaG and the temperature is 15~30℃.

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