Device and method for removing divalent ions from carbonated salt lake brine

Abstract

The present invention relates to a device and method for removing divalent ions from carbonate lake brine. The device comprises an inlet pump, a ceramic microfiltration system, a high-pressure pump, a three-stage nanofiltration membrane system, and a drainage pump. The ceramic microfiltration system uses a modified ceramic membrane with an open porosity of 29.3-35.1% and a water flux of 2.3-4.1 m 3 ·m ‑2 ·h ‑1 bar ‑1 The three-stage nanofiltration membrane system uses a modified nanofiltration membrane with a water contact angle of 35.1-38.2°C and a water flux of 8.2-9.5 L·m ‑2 ·h ‑1 bar ‑1 The device and method of the present invention can effectively remove divalent ions, especially calcium ions and carbonate ions, from carbonate salt lake brine, thereby removing impurities for the subsequent lithium extraction process and ensuring the purity of subsequent products.

Description

Technical Field

[0001] The invention belongs to the technical field of salt lake treatment, and in particular relates to a device and method for removing divalent ions in carbonate salt lake brine. Background Art

[0002] Carbonate-type salt lake brines are rich in lithium, boron, potassium, and trace elements such as bromine, cinnamate, and rubidium. Lake salt sedimentary minerals include halite, sylvite, thenardite, glauberite, gypsum, borax, magnesite, dolomite, trona, lithium dolomite, and zabyeite. Carbonate-type salt lakes contain carbonate ions at 11-48 g / L and lithium at 0.7-1.6 g / L.

[0003] In the prior art, in order to develop and utilize lithium in salt lake brine, there is a need to develop devices and methods for efficiently removing high-content divalent ions in brine. Summary of the Invention

[0004] The technical objective of this invention is to develop a device and method for effectively removing divalent ions from carbonate salt lake brine, based on the water quality and quantity of the brine, to ensure the subsequent comprehensive utilization of the carbonate salt lake. The device and method feature low one-time investment, simple operation, and low production and processing costs.

[0005] In one aspect, the present invention provides a device for removing divalent ions from carbonate salt lake brine, the device comprising, in order of brine treatment:

[0006] 1. Water inlet pump, which is used to transport salt lake brine into the ceramic microfiltration system;

[0007] 2. Ceramic microfiltration system, which is used to remove suspended matter, turbidity and algae from salt lake brine;

[0008] 3. A high-pressure pump, which is used to allow the micro-filtered salt lake brine to enter the three-stage nanofiltration membrane system;

[0009] 4. A three-stage nanofiltration membrane system, which is used to remove divalent ions from salt lake brine;

[0010] 5. A drainage pump, which is used to discharge the salt lake brine with divalent ions removed from the device,

[0011] The ceramic microfiltration system uses a modified ceramic membrane with an opening rate of 29.3-35.1% and a water flux of 2.3-4.1 m 3 ·m -2 ·h -1 bar -1 ,

[0012] The three-stage nanofiltration membrane system adopts a modified nanofiltration membrane with a water contact angle of 35.1-38.2°C and a water flux of 8.2-9.5 L·m -2 ·h -1 bar -1 .

[0013] In a specific embodiment, the divalent ions include calcium ions and carbonate ions. Preferably, the divalent ions are calcium ions and carbonate ions.

[0014] In the above, the three-stage nanofiltration membrane system refers to the brine to be treated passing through the nanofiltration membrane three times.

[0015] In a specific embodiment, the modified ceramic membrane is prepared by the following method:

[0016] 1) Screening D 50 12~15μm aluminum oxide and D 50 16-19 μm silicon dioxide;

[0017] 2) preparing a polyvinyl alcohol solution with a mass ratio of 12-15%, adding 35-65 g of the screened aluminum oxide, 15-21 g of the screened silicon dioxide, 3-8 g of analytically pure zirconium dioxide, 65-85 mL of a 12 wt% copper nitrate solution, and 0.1-0.9 g of carboxymethyl cellulose per liter of the polyvinyl alcohol solution, and stirring to prepare a mixed slurry;

[0018] 3) injecting the mixed slurry into a fixed metal mold and drying it, taking the green body out of the mold and placing it in a muffle furnace, heating it to 1350-1445° C. in an air atmosphere and maintaining the temperature for 2.5-2.9 hours to obtain a modified ceramic membrane.

[0019] In the preparation of modified ceramic membranes, the use of zirconium dioxide and copper nitrate helps improve porosity, as the smooth surface and straightness of zirconium dioxide and copper nitrate greatly increase the possibility of interconnection between the pores distributed around the fibers. Furthermore, the use of additives such as silica, zirconium dioxide, and copper nitrate results in larger pores during membrane pore formation, and the liquid tends to flow along the less curved fibers, shortening the originally tortuous flow path and thus increasing flux.

[0020] In a specific embodiment, the modified nanofiltration membrane is prepared by the following method:

[0021] 1) Prepare a dopamine solution, lay the nanofiltration base membrane flat and immerse it in the dopamine solution, and remove excess dopamine solution on the upper layer;

[0022] 2) adding n-hexane solution to the remaining dopamine solution, reacting, then removing the nanofiltration base membrane and washing it with n-hexane solution;

[0023] 3) preparing a glucose solution, adding 4-dimethylaminopyridine to the glucose solution to form a pyridine-glucose solution, heating the solution, and immersing the nanofiltration base membrane in the heated pyridine-glucose solution to react;

[0024] 4) After taking out the nanofiltration membrane, performing a drying heat treatment, and forming a modified nanofiltration membrane after cooling.

[0025] In a specific embodiment, in the preparation of the modified nanofiltration membrane,

[0026] In step 1), the solubility of the dopamine solution is 0.3-0.4%, and the immersion time is 25-35 minutes.

[0027] In a specific embodiment, in the preparation of the modified nanofiltration membrane,

[0028] In step 2), 20 to 25 mL of 0.4 wt% n-hexane solution is added per liter of dopamine solution and reacted for 2 to 5 minutes.

[0029] In a specific embodiment, in the preparation of the modified nanofiltration membrane,

[0030] In step 3), the concentration of the prepared glucose solution is 2.5-3.0% by mass. Preferably, 3-6 g of 4-dimethylaminopyridine is added to each liter of glucose solution to form a pyridine-glucose solution.

[0031] In a specific embodiment, in the preparation of the modified nanofiltration membrane,

[0032] In step 3), the nanofiltration base membrane is immersed in a pyridine-glucose solution at 65° C. and reacted for 10 to 12 minutes.

[0033] In a specific embodiment, in the preparation of the modified nanofiltration membrane,

[0034] In step 4), the nanofiltration membrane is heat-treated in a drying oven at 90° C. for 20 to 25 minutes.

[0035] In another aspect, the present invention provides a method for removing divalent ions from carbonate salt lake brine using the above-mentioned device, the method comprising the following steps:

[0036] 1) The carbonated salt lake brine enters the ceramic microfiltration system through the water inlet pump;

[0037] 2) treating carbonate salt lake brine by the ceramic microfiltration system;

[0038] 3) The brine from the salt lake that has undergone microfiltration treatment is fed into the three-stage nanofiltration membrane system through a high-pressure pump;

[0039] 4) using the three-stage nanofiltration membrane system to treat the microfiltered salt lake brine;

[0040] 5) The salt lake brine treated by nanofiltration is discharged through a drainage pump.

[0041] In a specific embodiment, the divalent ions include calcium ions and carbonate ions. Preferably, the divalent ions are calcium ions and carbonate ions. In a specific embodiment, in step 1), the carbonate salt lake brine has a calcium ion content of 2-11 mg / L, a carbonate ion content of 11-48 g / L, a lithium ion content of 0.7-1.6 g / L, a turbidity content of 123-238 NTU, and a chlorophyll a content of 0.8-1.7 μg / L.

[0042] In a specific embodiment, in step 2), the water inlet pressure of the ceramic microfiltration system is 0.7 to 2.3 bar, full-flow filtration is performed, suspended particles between 0.1 and 0.3 μm are retained, and after treatment by the ceramic microfiltration system, the turbidity of the carbonate salt lake brine is 2 to 10 NTU, and the chlorophyll a is 0 to 0.06 μg / L.

[0043] In a specific embodiment, in step 3), the pressure of the high-pressure pump is 5.5-9.2 MPa.

[0044] In a specific embodiment, in step 4), after passing through the three-stage nanofiltration membrane system, the calcium ion in the salt lake brine is 0-0.02 mg / L, the carbonate ion is 60-150 mg / L, the lithium ion is 0.5-1.1 g / L, the turbidity is 3-10 NTU, and chlorophyll a is not detected.

[0045] According to the present invention, the drainage pump discharges the salt lake brine with divalent ions removed from the device and then sends it into the brine lithium extraction process unit for producing lithium carbonate or lithium hydroxide.

[0046] On the other hand, the present invention provides the use of the brine obtained by the above method in a lithium extraction process.

[0047] Beneficial effects

[0048] After the salt lake brine is treated by the device of the present invention, calcium ions and carbonate ions in the carbonate-type salt lake brine are effectively removed, impurities are removed for the subsequent lithium extraction process, and the purity of subsequent products is ensured.

[0049] Therefore, the present invention belongs to a green salt lake production process and has good social and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The device for removing divalent ions from carbonate salt lake brine according to the present invention is schematically shown.

[0051] Description of Reference Numerals

[0052] 1-water inlet pump, 2-ceramic microfiltration system, 3-modified ceramic membrane, 4-high pressure pump, 5-three-stage nanofiltration membrane system, 6-modified nanofiltration membrane, 7-drainage pump. DETAILED DESCRIPTION

[0053] the term

[0054] In this application, the “opening ratio” (Φ, expressed in %) is the ratio of the total area A0 of the sieve holes on the sieve plate to the area A of the opening area (also known as the effective mass transfer area). a The ratio of Φ(%) = A0 / A a .

[0055] In this application, "solution", unless otherwise specified, refers to an aqueous solution.

[0056] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0057] Unless otherwise specified, the raw materials involved in this application are commercially available, and the equipment and methods used are conventional equipment and methods in the art.

[0058] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0059] Example 1:

[0060] like Figure 1 As shown, the device for removing divalent ions from a carbonate salt lake includes a water inlet pump 1, a ceramic microfiltration system 2, a modified ceramic membrane 3, a high-pressure pump 4, a three-stage nanofiltration membrane system 5, a modified nanofiltration membrane 6, and a drainage pump 7.

[0061] The carbonate salt lake brine contains 10 mg / L of calcium ions, 42 g / L of carbonate ions, 1.3 g / L of lithium ions, 231 NTU of turbidity, and 1.3 μg / L of chlorophyll a.

[0062] The salt lake brine enters the ceramic microfiltration system 2 via an inlet pump 1, where a modified ceramic membrane 3 is placed. The system removes suspended matter, turbidity, and algae from the salt lake brine, ensuring the stable operation of the subsequent nanofiltration system. The system operates at an inlet pressure of 2.1 bar, performing full-flow filtration and retaining suspended particles as small as 0.3 μm. After treatment, the carbonated salt lake brine has a turbidity of 8 NTU and a chlorophyll a level of 0.03 μg / L.

[0063] The modified ceramic membrane 3 in the ceramic microfiltration system 2 is prepared by the following method: 1) screening D 50 15μm aluminum oxide and D50 19μm silica; 2) Prepare a polyvinyl alcohol solution with a mass ratio of 15%, add 65g of screened alumina, 21g of screened silica, 8g of analytical pure zirconium dioxide, 85mL of 12% copper nitrate solution and 0.7g of carboxymethyl cellulose to each liter of polyvinyl alcohol solution, and stir mechanically at a speed of 150 rpm for 25 minutes to prepare a mixed slurry; 3) Inject the mixed slurry into a fixed metal mold, dry at 72°C for 8h, take the green body out of the mold and put it into a muffle furnace, heat it to 1435°C at 9°C / min in an air atmosphere, and keep the temperature constant for 2.8h to obtain a modified ceramic membrane. The porosity of the prepared modified ceramic membrane is 35.0%. The pure water membrane flux of the modified ceramic membrane is 3.8m 3 ·m -2 ·h -1 bar -1 .

[0064] The salt lake brine then enters the three-stage nanofiltration membrane system 5 through a high-pressure pump 4. The three-stage nanofiltration membrane system 5 is equipped with a modified nanofiltration membrane 6. The pressure of the high-pressure pump 4 is 8.7 MPa.

[0065] The modified nanofiltration membrane 6 in the three-stage nanofiltration membrane system 5 is prepared by the following method: 1) Prepare a dopamine solution with a mass ratio of 0.4%, lay the commercial nanofiltration base membrane flat and immerse it in the dopamine solution, remove the excess dopamine solution on the upper layer, and the immersion time is 35 minutes. 2) Add 25 mL of 0.4% n-hexane solution to each liter of dopamine solution, react for 5 minutes, then remove the nanofiltration base membrane and wash it with n-hexane solution 3 times. 3) Prepare a glucose solution with a mass ratio of 3.0%, add 6 g of 4-dimethylaminopyridine to each liter of glucose solution to form a pyridine-glucose solution, heat the solution to 65°C, immerse the nanofiltration base membrane in the pyridine-glucose solution at this temperature, react for 12 minutes, remove the nanofiltration membrane and heat treat it in a 90°C drying oven for 25 minutes, and form a modified nanofiltration membrane after cooling. The water contact angle of the modified nanofiltration membrane is 37.6°C and the water flux is 9.1 L·m -2 ·h -1 bar -1 , indicating that it has stronger hydrophilicity, and the water transfer efficiency can be improved by forming a hydration layer on the surface of the modified nanofiltration membrane.

[0066] After passing through the three-stage nanofiltration membrane system 5, the calcium ion in the salt lake brine was 0.01 mg / L, the carbonate ion was 123 mg / L, the lithium ion was 1.0 g / L, the turbidity was 5 NTU, and chlorophyll a was not detected.

[0067] Finally, the drainage pump 7 pumps the treated salt lake brine into the subsequent brine lithium extraction process unit to produce lithium carbonate or lithium hydroxide.

[0068] Example 2

[0069] like Figure 1 As shown, the device for removing divalent ions from a carbonate salt lake includes a water inlet pump 1, a ceramic microfiltration system 2, a modified ceramic membrane 3, a high-pressure pump 4, a three-stage nanofiltration membrane system 5, a modified nanofiltration membrane 6, and a drainage pump 7.

[0070] The carbonate salt lake brine contains 5 mg / L of calcium ions, 19 g / L of carbonate ions, 0.9 g / L of lithium ions, 156 NTU of turbidity, and 0.9 μg / L of chlorophyll a.

[0071] The salt lake brine enters the ceramic microfiltration system 2 via an inlet pump 1, where a modified ceramic membrane 3 is placed. The system removes suspended matter, turbidity, and algae from the brine, ensuring the stable operation of the subsequent nanofiltration system. The system operates at an inlet pressure of 0.9 bar, performing full-flow filtration and retaining suspended particles as small as 0.2 μm. After treatment, the carbonated salt lake brine has a turbidity of 5 NTU and a chlorophyll a level of 0.02 μg / L.

[0072] The modified ceramic membrane 3 in the ceramic microfiltration system 2 is prepared by the following method: 1) screening D 50 12μm aluminum oxide and D 50 16μm silica; 2) Prepare a polyvinyl alcohol solution with a mass ratio of 12%, add 37g of screened alumina, 17g of screened silica, 4g of analytical pure zirconium dioxide, 65mL of 12% copper nitrate solution and 0.2g of carboxymethyl cellulose per liter of polyvinyl alcohol solution, and stir mechanically at a speed of 150 rpm for 10 minutes to prepare a mixed slurry; 3) Inject the mixed slurry into a fixed metal mold, dry at 69°C for 6h, take the green body out of the mold and put it into a muffle furnace, heat it to 1355°C at 8°C / min in an air atmosphere, and keep the temperature constant for 2.6h to obtain a modified ceramic membrane. The porosity of the prepared modified ceramic membrane is 30.1%. The pure water membrane flux of the modified ceramic membrane is 2.5m 3 ·m -2 ·h -1 bar -1 .

[0073] Then the salt lake brine enters the three-stage nanofiltration membrane system 5 through the high-pressure pump 4. The three-stage nanofiltration membrane system 5 is placed with a modified nanofiltration membrane 6. The pressure of the high-pressure pump 4 is 7.8 MPa.

[0074] The modified nanofiltration membrane 6 in the three-stage nanofiltration membrane system 5 is prepared by the following method: 1) Prepare a dopamine solution with a mass ratio of 0.3%, lay the commercial nanofiltration base membrane flat and immerse it in the dopamine solution, remove the excess dopamine solution on the upper layer, and the immersion time is 25 minutes. 2) Add 20 mL of n-hexane solution with a mass ratio of 0.4% to each liter of dopamine solution, react for 2 minutes, then remove the nanofiltration base membrane and wash it twice with n-hexane solution. 3) Prepare a glucose solution with a mass ratio of 2.6%, add 3 g of 4-dimethylaminopyridine to each liter of glucose solution to form a pyridine-glucose solution, heat the solution to 65°C, immerse the nanofiltration base membrane in the pyridine-glucose solution at this temperature, react for 10 minutes, remove the nanofiltration membrane and heat treat it in a drying oven at 90°C for 20 minutes, and form a modified nanofiltration membrane after cooling. The water contact angle of the modified nanofiltration membrane is 35.9°C and the water flux is 8.7 L·m -2 ·h -1 bar -1 , indicating that it has stronger hydrophilicity, and the water transfer efficiency can be improved by forming a hydration layer on the surface of the modified nanofiltration membrane.

[0075] After passing through the three-stage nanofiltration membrane system 5, the calcium ion in the salt lake brine was 0.01 mg / L, the carbonate ion was 69 mg / L, the lithium ion was 0.7 g / L, the turbidity was 4 NTU, and chlorophyll a was not detected.

[0076] Finally, the drainage pump 7 pumps the treated salt lake brine into the subsequent brine lithium extraction process unit to produce lithium carbonate or lithium hydroxide.

[0077] Of course, those skilled in the art should realize that the above embodiments are only used to illustrate the present invention and are not used to limit the present invention. As long as they are within the scope of the essential spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A device for removing divalent ions from carbonate salt lake brine, the device comprising, in order of brine treatment: Inlet pump, which is used to transport salt lake brine into the ceramic microfiltration system; Ceramic microfiltration systems, which are used to remove suspended solids, turbidity, and algae from salt lake brine; A high-pressure pump is used to allow the microfiltered salt lake brine to enter the three-stage nanofiltration membrane system; A three-stage nanofiltration membrane system is used to remove divalent ions from salt lake brine; a drainage pump for discharging the salt lake brine from which divalent ions have been removed from the device; The ceramic microfiltration system uses a modified ceramic membrane with an opening rate of 29.3-35.1% and a water flux of 2.3-4.1 m 3 ·m -2 ·h -1 bar -1 , and the modified ceramic membrane is prepared by the following method: 1) Filter D 50 12~15μm aluminum oxide and D 50 16~19 μm silicon dioxide; 2) Prepare a polyvinyl alcohol solution with a mass ratio of 12-15%, add 35-65 g of the above-screened aluminum oxide, 15-21 g of the above-screened silicon dioxide, 3-8 g of analytical grade zirconium dioxide, 65-85 mL of 12 wt% copper nitrate solution, and 0.1-0.9 g of carboxymethyl cellulose per liter of the polyvinyl alcohol solution, and stir to prepare a mixed slurry; 3) Pour the mixed slurry into a fixed metal mold and dry it. After removing the green body from the mold, place it in a muffle furnace and heat it to 1350~1445℃ in an air atmosphere for 2.5~2.9 hours to obtain a modified ceramic membrane. The three-stage nanofiltration membrane system uses a modified nanofiltration membrane with a water contact angle of 35.1-38.2°C and a water flux of 8.2-9.5 L·m -2 ·h -1 bar -1 .

2. The device according to claim 1, wherein The divalent ions include calcium ions and carbonate ions.

3. The device according to claim 1, wherein The modified nanofiltration membrane is prepared by the following method: 1) Prepare dopamine solution, lay the nanofiltration base membrane flat and immerse it in the dopamine solution, and remove the excess dopamine solution on the top layer; 2) Add n-hexane solution to the remaining dopamine solution, react, then remove the nanofiltration base membrane and wash it with n-hexane solution; 3) preparing a glucose solution, adding 4-dimethylaminopyridine to the glucose solution to form a pyridine-glucose solution, heating the solution, and immersing the nanofiltration base membrane in the heated pyridine-glucose solution to react; 4) After taking out the nanofiltration membrane, dry heat treatment is performed, and a modified nanofiltration membrane is formed after cooling.

4. The device according to claim 3, wherein In the preparation of the modified nanofiltration membrane, In step 1), the solubility of the dopamine solution is 0.3-0.4%, and the immersion time is 25-35 minutes; and / or In step 2), 20 to 25 mL of 0.4 wt% n-hexane solution is added per liter of dopamine solution and the mixture is reacted for 2 to 5 minutes; and / or In step 3), the glucose solution is prepared to a concentration of 2.5-3.0% by mass, 3-6 g of 4-dimethylaminopyridine is added to each liter of the glucose solution to form a pyridine-glucose solution, and the nanofiltration base membrane is immersed in the pyridine-glucose solution at 65°C and reacted for 10-12 minutes; and / or In step 4), the nanofiltration membrane is heat-treated in a drying oven at 90°C for 20 to 25 minutes.

5. A method for removing divalent ions from carbonate salt lake brine using the apparatus according to any one of claims 1 to 4, the method comprising the following steps: 1) The carbonated salt lake brine enters the ceramic microfiltration system through the water inlet pump; 2) treating carbonate salt lake brine by the ceramic microfiltration system; 3) The brine from the salt lake that has undergone microfiltration treatment is pumped into the three-stage nanofiltration membrane system through a high-pressure pump; 4) using the three-stage nanofiltration membrane system to treat the microfiltered salt lake brine; 5) The salt lake brine treated by nanofiltration is discharged through a drainage pump.

6. The method according to claim 5, wherein In step 1), the carbonate salt lake brine has a calcium ion content of 2-11 mg / L, a carbonate ion content of 11-48 g / L, a lithium ion content of 0.7-1.6 g / L, a turbidity content of 123-238 NTU, and a chlorophyll a content of 0.8-1.7 μg / L.

7. The method according to claim 5, wherein In step 2), the water inlet pressure of the ceramic microfiltration system is 0.7~2.3 bar, full-flow filtration is performed, and suspended particles between 0.1~0.3 μm are retained. After treatment by the ceramic microfiltration system, the turbidity of the carbonate salt lake brine is 2~10 NTU and the chlorophyll a is 0~0.06 μg / L.

8. The method according to claim 5, wherein In step 3), the pressure of the high-pressure pump is 5.5-9.2 MPa; and / or In step 4), after passing through the three-stage nanofiltration membrane system, the calcium ion content in the salt lake brine was 0~0.02 mg / L, the carbonate ion content was 60~150 mg / L, the lithium ion content was 0.5~1.1 g / L, the turbidity content was 3~10 NTU, and chlorophyll a was not detected.

9. Use of brine obtained by the method according to any one of claims 5 to 8 in a lithium extraction process.

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