Lithium extraction device system for high-grade brine

Abstract

The utility model provides a lithium extraction device system for high-grade brine, which comprises a pretreatment unit, a first multi-stage nanofiltration device, an evaporative crystallization device and a purification unit which are sequentially connected according to the flowing direction of the high-grade brine, the pretreatment unit comprises a filter pressing device and a membrane separation module which are connected in sequence; and the purification unit comprises a second multi-stage nanofiltration device or a double-alkali reaction device. By adopting the lithium extraction device system provided by the utility model, the recovery rate of lithium is improved, and the dosing and operating cost and the investment cost of the device system are reduced; and the lithium extraction device system is simple in structure and simple to operate, and has a relatively good industrial application prospect.

Description

Technical Field

[0001] The utility model belongs to the technical field of lithium extraction from brine, and in particular relates to a lithium extraction device system and a lithium extraction method for high-grade brine. Background Art

[0002] Lithium and its compounds play an extremely important role in the fields of energy, petrochemicals, metallurgy, ceramics, medicine, aerospace, refrigeration, etc., and are known as the "energy metal of the 21st century". Therefore, the global demand for lithium is also growing at an annual rate of 8-12%, and the market price of lithium and lithium salts has also maintained an upward trend. The world's salt lake lithium resources account for more than 70% of the total lithium resources and will be the main direction of lithium resource development in the future. Since magnesium and lithium are similar in nature and difficult to separate, the use of solvent extraction can reduce the magnesium-to-lithium ratio and has a high lithium enrichment rate. At the same time, it has the characteristics of simple extraction operation and cyclic continuous production. It has good development prospects in the extraction of lithium from salt lake brine in my country.

[0003] At present, the main methods for extracting lithium from salt lake brine include evaporation crystallization separation, precipitation, calcination leaching, organic solvent extraction, ion exchange adsorption, electrodialysis, Xu's method and nanofiltration, etc. The post-processing steps are generally impurity removal, concentration, precipitation, etc. The pre-treatment process, product quality and economic benefits of lithium extraction are closely related to the lithium concentration and magnesium-lithium ratio in the brine. Low lithium concentration and high magnesium-lithium ratio will seriously limit the process combination of lithium extraction from brine, affecting its feasibility and economic benefits. Nanofiltration can effectively separate monovalent ions and polyvalent ions, but conventional nanofiltration systems can only process salt lake brines with very high salt content after diluting them several times.

[0004] CN 103570048A discloses a method for refining lithium from salt lake brine with a high magnesium-to-lithium ratio. The method separates magnesium ions and lithium ions through a nanofiltration system, enriches lithium ions through a reverse osmosis system, and concentrates by evaporation in salt pans, so that the lithium ion concentration can reach the concentration required for refining lithium carbonate. However, the nanofiltration system designed in the patent has only one stage, and the magnesium-lithium separation capacity is limited. It has a poor treatment effect on brine with a high magnesium-to-lithium ratio and has certain limitations. In addition, after reverse osmosis concentration, it still needs to be further concentrated by salt pan evaporation, which takes a long time, so that the lithium ion concentration can reach the requirement for producing lithium carbonate.

[0005] In summary, providing an effective lithium extraction process that is suitable for the project site is of great significance to the development of local lithium resources. Utility Model Content

[0006] In view of the shortcomings of the prior art, the purpose of the utility model is to provide a lithium extraction device system for high-grade brine. The lithium extraction device system provided by the utility model improves the lithium recovery rate and reduces the device system dosing, operation cost and device system investment cost.

[0007] To achieve this purpose, the utility model adopts the following technical solutions:

[0008] In the first aspect, the utility model provides a lithium extraction device system for high-grade brine. According to the flow direction of the high-grade brine, the lithium extraction device system includes a pretreatment unit, a first multi-stage nanofiltration device, an evaporation crystallization device and a purification unit which are sequentially connected;

[0009] The pretreatment unit comprises a filter press device and a membrane separation module which are sequentially connected;

[0010] The purification unit includes a second multi-stage nanofiltration device or a dual-alkali reaction device.

[0011] In the utility model, the lithium ion content in the high-grade brine is 0.5-3g / L, the magnesium ion content is 3-25g / L, and the calcium ion content is 0.2-1g / L. The high-grade brine can effectively reduce the calcium, magnesium and sulfate content in the brine through the pretreatment unit and the first multi-stage nanofiltration device, and then remove part of the sodium chloride through the evaporation crystallization device, while obtaining the fresh water required for production and increasing the lithium content in the concentrated solution; finally, the purification unit is used to further purify and remove impurities to obtain a high-purity lithium chloride solution, which is finally used to produce lithium carbonate products.

[0012] As a preferred technical solution of the utility model, the filter press device includes a plate and frame filter press.

[0013] The mesh number of the filter cloth used in the plate and frame filter press is 400-600 meshes, for example, it can be 400 meshes, 440 meshes, 480 meshes, 520 meshes, 560 meshes or 600 meshes, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0014] In the utility model, a plate and frame filter press is initially used to remove large suspended impurities in the high-quality brine, and the qualified filtrate is used as the raw material liquid of the subsequent membrane separation module for further impurity removal.

[0015] As a preferred technical solution of the utility model, the membrane separation module includes a ceramic membrane separation device and a ceramic membrane water production tank which are connected to each other.

[0016] The pore size of the ceramic membrane in the ceramic membrane separation device is 25 to 100 nm, for example, it can be 25 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0017] In the utility model, the ceramic membrane separation device can be used to effectively further remove impurities, colloids and other impurities in the original high-grade brine, ensuring the stable operation of the subsequent nanofiltration treatment.

[0018] As a preferred technical solution of the utility model, a pressure pump is arranged between the ceramic membrane water production tank and the first multi-stage nanofiltration device.

[0019] The first multi-stage nanofiltration device is a two-stage nanofiltration device.

[0020] The filtrate outlet of the first multi-stage nanofiltration device is connected to the evaporation crystallization device.

[0021] The concentrated liquid outlet of the first multi-stage nanofiltration device is connected to the salt field.

[0022] In the utility model, the first multi-stage nanofiltration device is used to separate impurities from lithium chloride, and can remove impurities such as calcium, magnesium, and sulfate. After nanofiltration, the removal rate of magnesium ions and sulfate ions is greater than 95%, and the removal rate of calcium ions is greater than 70%. The nanofiltration concentrate is returned to the salt field for reuse.

[0023] As a preferred technical solution of the present utility model, the evaporation crystallization device includes an MVR evaporation crystallization device.

[0024] As a preferred technical solution of the utility model, the mother liquor outlet of the evaporation crystallization device is connected to the purification unit.

[0025] The solid outlet of the evaporation crystallization device is connected to the concentrated liquid outlet of the first multi-stage nanofiltration device.

[0026] The condensed water outlet of the evaporation crystallization device is connected to the reverse osmosis device.

[0027] In the utility model, the evaporation crystallization device realizes the separation of lithium chloride and sodium chloride, and the sodium chloride crystals produced by the solid outlet of the evaporation crystallization device can be dissolved in the concentrated liquid obtained by the first multi-stage nanofiltration device and then returned to the salt field for storage.

[0028] As a preferred technical solution of the utility model, the outlet of the reverse osmosis device is connected to the inlet of the first multi-stage nanofiltration device through a reverse osmosis water production tank.

[0029] As a preferred technical solution of the present utility model, the second multi-stage nanofiltration device includes a two-stage nanofiltration device.

[0030] As a preferred technical solution of the utility model, the dual-alkali reaction device includes a reaction pool and a storage tank which are connected in sequence.

[0031] As a preferred technical solution of the utility model, the reaction tank is provided with an additive filling port;

[0032] The mother liquor outlet of the evaporation crystallization device is connected to the inlet of the reaction tank.

[0033] In the utility model, nanofiltration membrane or double alkali method is adopted to remove the remaining calcium, magnesium and sulfate impurities, and the obtained lithium chloride solution with higher purity is used to produce lithium carbonate products.

[0034] In the present invention, the types of nanofiltration membranes used in the first multi-stage nanofiltration device and the second multi-stage nanofiltration device are not limited, as long as the impurity removal or separation treatment of the high-grade brine can be achieved.

[0035] In a second aspect, the utility model provides a lithium extraction method using the lithium extraction device system provided in the first aspect, the lithium extraction method comprising the following steps:

[0036] (1) using a pretreatment unit to remove impurities from high-grade brine to obtain a removed impurity filtrate;

[0037] (2) using a first multi-stage nanofiltration device to perform nanofiltration treatment on the impurity-removed filtrate obtained in step (1) to obtain a nanofiltration concentrate and a nanofiltration filtrate;

[0038] (3) using an evaporation crystallization device to evaporate and crystallize the nanofiltration filtrate obtained in step (2) to obtain a mother liquor, sodium chloride crystals and condensed water;

[0039] (4) using a purification unit to perform secondary impurity removal on the mother liquor obtained in step (3) to obtain a lithium chloride solution.

[0040] Preferably, the impurity removal treatment in step (1) comprises pressure filtration and ceramic membrane filtration performed sequentially.

[0041] Preferably, the pressure of the filtration is 7 to 8 MPa, for example, 7 MPa, 7.2 MPa, 7.4 MPa, 7.6 MPa, 7.8 MPa or 8 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0042] Preferably, the filtration accuracy of the filter press is 400-600 mesh, for example, it can be 400 mesh, 440 mesh, 480 mesh, 520 mesh, 560 mesh or 600 mesh, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0043] Preferably, the filtration accuracy of the ceramic membrane filtration is 25 to 100 nm, for example, it can be 25 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0044] Preferably, the nanofiltration treatment in step (2) includes primary nanofiltration and secondary nanofiltration performed sequentially.

[0045] Preferably, the pressure of the primary nanofiltration is 6-8 MPa, for example, 6 MPa, 6.4 MPa, 6.8 MPa, 7.2 MPa, 7.6 MPa or 8 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0046] Preferably, the pressure of the secondary nanofiltration is 2.5-4 MPa, for example, 2.5 MPa, 2.8 MPa, 3.1 MPa, 3.4 MPa, 3.7 MPa or 4 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0047] Preferably, the temperature of the evaporation crystallization in step (3) is 96-106°C, for example, 96°C, 98°C, 100°C, 102°C, 104°C or 106°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0048] Preferably, the secondary impurity removal in step (4) includes nanofiltration impurity removal or double alkali method impurity removal.

[0049] Preferably, the nanofiltration impurity removal includes primary nanofiltration impurity removal and secondary nanofiltration impurity removal performed sequentially.

[0050] Preferably, the pressure of the primary nanofiltration impurity removal is 3 to 8 MPa, for example, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, 6 MPa, 7 MPa or 8 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0051] Preferably, the pressure of the secondary nanofiltration impurity removal is 2 to 4 MPa, for example, 2MPa, 2.4MPa, 2.8MPa, 3.2MPa, 3.6MPa or 4MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0052] Preferably, the double alkali method for impurity removal comprises: mixing the mother liquor obtained in step (3) with alkali solution.

[0053] Preferably, the alkali solution comprises sodium hydroxide solution and sodium carbonate.

[0054] Preferably, the order of adding the alkali solution is: first adding the sodium hydroxide solution, and then adding the sodium carbonate.

[0055] Compared with the prior art, the beneficial effects of the utility model are:

[0056] (1) The lithium extraction device system provided by the utility model improves the recovery rate of lithium, reduces the dosing and operation costs of the device system and the investment cost of the device system; and no waste liquid is generated during the lithium extraction process, which belongs to the green recovery technology;

[0057] (2) The lithium extraction device provided by the utility model has a simple system structure and is easy to operate. After crystallization and evaporation, a purification unit is used to remove impurities, which further improves the purity of lithium and realizes efficient recycling of lithium, thus having good prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 A schematic diagram of a lithium extraction device system for high-grade brine provided in a specific embodiment of the utility model;

[0059] Among them: 1 is a filter press device, 2 is a ceramic membrane separation device, 3 is a ceramic membrane water production tank, 4 is a pressure pump, 5 is a first multi-stage nanofiltration device, 6 is an MVR evaporation crystallization device, 7 is a purification unit, 8 is a reverse osmosis device, and 9 is a reverse osmosis water production tank. DETAILED DESCRIPTION

[0060] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0061] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0062] The technical solution of the utility model is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0063] The utility model provides a Figure 1 The lithium extraction device system for high-grade brine shown in the figure includes a pretreatment unit, a first multi-stage nanofiltration device 5, an evaporation crystallization device and a purification unit which are sequentially connected according to the flow direction of the high-grade brine;

[0064] The pretreatment unit comprises a filter press device 1 and a membrane separation module which are sequentially connected; the purification unit comprises a second multi-stage nanofiltration device or a dual-alkali reaction device.

[0065] The filter press device 1 comprises a plate-frame filter press; the mesh number of the filter cloth used in the plate-frame filter press is 400-600 meshes;

[0066] The membrane separation module comprises a ceramic membrane separation device 2 and a ceramic membrane water production box 3 which are connected to each other; the pore size of the ceramic membrane in the ceramic membrane separation device 2 is 25 to 100 nm;

[0067] A pressure pump 4 is provided between the ceramic membrane water production tank 3 and the first multi-stage nanofiltration device 5; the first multi-stage nanofiltration device 5 is a two-stage nanofiltration device; the filtrate outlet of the first multi-stage nanofiltration device 5 is connected to the evaporation crystallization device; the concentrated liquid outlet of the first multi-stage nanofiltration device 5 is connected to the salt pan;

[0068] The evaporation crystallization device comprises an MVR evaporation crystallization device 6; the mother liquid outlet of the evaporation crystallization device is connected to the purification unit 7; the solid outlet of the evaporation crystallization device is connected to the concentrated liquid outlet of the first multi-stage nanofiltration device 5; the condensed water outlet of the evaporation crystallization device is connected to the reverse osmosis device 8;

[0069] The outlet of the reverse osmosis device 8 is connected to the inlet of the first multi-stage nanofiltration device 5 through a reverse osmosis water production tank 9;

[0070] The second multi-stage nanofiltration device includes a secondary nanofiltration device; the dual-alkali reaction device includes a reaction tank and a storage tank connected in sequence; the reaction tank is provided with an additive filling port; the mother liquor outlet of the evaporation crystallization device is connected to the inlet of the reaction tank.

[0071] The lithium extraction method using the above-mentioned lithium extraction device system comprises the following steps:

[0072] (1) using a pretreatment unit to remove impurities from high-grade brine to obtain a removed impurity filtrate;

[0073] The impurity removal treatment includes pressure filtration and ceramic membrane filtration performed in sequence; the pressure of the pressure filtration is 7-8 MPa, the filtration precision is 400-600 mesh; the filtration precision of the ceramic membrane filtration is 25-100 nm;

[0074] (2) using a first multi-stage nanofiltration device to perform nanofiltration treatment on the impurity-removed filtrate obtained in step (1) to obtain a nanofiltration concentrate and a nanofiltration filtrate;

[0075] Wherein, the nanofiltration treatment includes a primary nanofiltration at a pressure of 6 to 8 MPa and a secondary nanofiltration at a pressure of 2.5 to 4 MPa, which are performed sequentially;

[0076] (3) using an evaporation crystallization device to evaporate and crystallize the nanofiltration filtrate obtained in step (2) at 96 to 106° C. to obtain a mother liquor, sodium chloride crystals and condensed water;

[0077] (4) using a purification unit to perform secondary impurity removal on the mother liquor obtained in step (3) to obtain a lithium chloride solution;

[0078] Wherein, the secondary impurity removal includes nanofiltration impurity removal or double alkali method impurity removal;

[0079] The nanofiltration impurity removal includes a primary nanofiltration impurity removal at a pressure of 3 to 8 MPa and a secondary nanofiltration impurity removal at a pressure of 2 to 4 MPa.

[0080] The double alkali method for impurity removal comprises: sequentially mixing sodium hydroxide solution and sodium carbonate into the mother liquor obtained in step (3).

[0081] Example 1

[0082] This embodiment provides a lithium extraction device system for high-grade brine. According to the flow direction of the high-grade brine, the lithium extraction device system includes a pretreatment unit, a first multi-stage nanofiltration device 5, an evaporation crystallization device and a purification unit which are sequentially connected;

[0083] The pretreatment unit comprises a filter press device 1 and a membrane separation module which are sequentially connected; the purification unit comprises a second multi-stage nanofiltration device.

[0084] The filter press device 1 includes a plate-frame filter press; the mesh number of the filter cloth used in the plate-frame filter press is 500 mesh; the membrane separation module includes a ceramic membrane separation device 2 and a ceramic membrane water production tank 3 which are connected and arranged; the pore size of the ceramic membrane in the ceramic membrane separation device 2 is 60nm;

[0085] A pressure pump 4 is provided between the ceramic membrane water production tank 3 and the first multi-stage nanofiltration device 5; the first multi-stage nanofiltration device 5 is a two-stage nanofiltration device; the filtrate outlet of the first multi-stage nanofiltration device 5 is connected to the evaporation crystallization device; the concentrated liquid outlet of the first multi-stage nanofiltration device 5 is connected to the salt pan;

[0086] The evaporation crystallization device comprises an MVR evaporation crystallization device 6; the mother liquid outlet of the evaporation crystallization device is connected to the purification unit 7; the solid outlet of the evaporation crystallization device is connected to the concentrated liquid outlet of the first multi-stage nanofiltration device 5; the condensed water outlet of the evaporation crystallization device is connected to the reverse osmosis device 8;

[0087] The outlet of the reverse osmosis device 8 is connected to the inlet of the first multi-stage nanofiltration device 5 through a reverse osmosis water production tank 9;

[0088] The second multi-stage nanofiltration device includes a two-stage nanofiltration device.

[0089] The lithium extraction method performed by the lithium extraction device system provided in this embodiment includes the following steps:

[0090] (1) using a pretreatment unit to remove impurities from high-grade brine to obtain a removed impurity filtrate;

[0091] The impurity removal treatment includes pressure filtration and ceramic membrane filtration performed in sequence; the pressure of the pressure filtration is 7.5 MPa, the filtration precision is 500 mesh; the filtration precision of the ceramic membrane filtration is 60 nm;

[0092] (2) using a first multi-stage nanofiltration device to perform nanofiltration treatment on the impurity-removed filtrate obtained in step (1) to obtain a nanofiltration concentrate and a nanofiltration filtrate;

[0093] Wherein, the nanofiltration treatment includes a primary nanofiltration at a pressure of 7 MPa and a secondary nanofiltration at a pressure of 3.2 MPa, which are performed sequentially;

[0094] (3) using an evaporation crystallization device to evaporate and crystallize the nanofiltration filtrate obtained in step (2) at 103° C. to obtain a mother liquor, sodium chloride crystals and condensed water;

[0095] (4) using a purification unit to perform secondary impurity removal on the mother liquor obtained in step (3) to obtain a lithium chloride solution;

[0096] Wherein, the secondary impurity removal includes nanofiltration impurity removal; the nanofiltration impurity removal includes a primary nanofiltration impurity removal at a pressure of 2.5 to 4 MPa and a secondary nanofiltration impurity removal at a pressure of 2 to 3 MPa performed sequentially.

[0097] Example 2

[0098] This embodiment provides a lithium extraction device system for high-grade brine. According to the flow direction of the high-grade brine, the lithium extraction device system includes a pretreatment unit, a first multi-stage nanofiltration device 5, an evaporation crystallization device and a purification unit which are sequentially connected;

[0099] The pretreatment unit comprises a filter press device 1 and a membrane separation module which are sequentially connected; the purification unit comprises a dual-alkali reaction device.

[0100] The filter press device 1 includes a plate-frame filter press; the mesh number of the filter cloth used in the plate-frame filter press is 400 meshes; the membrane separation module includes a ceramic membrane separation device 2 and a ceramic membrane water production tank 3 which are connected and arranged; the pore size of the ceramic membrane in the ceramic membrane separation device 2 is 25 nm;

[0101] A pressure pump 4 is provided between the ceramic membrane water production tank 3 and the first multi-stage nanofiltration device 5; the first multi-stage nanofiltration device 5 is a two-stage nanofiltration device; the filtrate outlet of the first multi-stage nanofiltration device 5 is connected to the evaporation crystallization device; the concentrated liquid outlet of the first multi-stage nanofiltration device 5 is connected to the salt pan;

[0102] The evaporation crystallization device comprises an MVR evaporation crystallization device 6; the mother liquid outlet of the evaporation crystallization device is connected to the purification unit 7; the solid outlet of the evaporation crystallization device is connected to the concentrated liquid outlet of the first multi-stage nanofiltration device 5; the condensed water outlet of the evaporation crystallization device is connected to the reverse osmosis device 8;

[0103] The outlet of the reverse osmosis device 8 is connected to the inlet of the first multi-stage nanofiltration device 5 through a reverse osmosis water production tank 9;

[0104] The dual-alkali reaction device comprises a reaction pool and a storage tank which are connected in sequence; the reaction pool is provided with an additive filling port; and the mother liquor outlet of the evaporation crystallization device is connected to the inlet of the reaction pool.

[0105] The lithium extraction method performed by the lithium extraction device system provided in this embodiment includes the following steps:

[0106] (1) using a pretreatment unit to remove impurities from high-grade brine to obtain a removed impurity filtrate;

[0107] The impurity removal treatment includes pressure filtration and ceramic membrane filtration performed in sequence; the pressure of the pressure filtration is 7.2 MPa, the filtration precision is 400 mesh; the filtration precision of the ceramic membrane filtration is 25 nm;

[0108] (2) using a first multi-stage nanofiltration device to perform nanofiltration treatment on the impurity-removed filtrate obtained in step (1) to obtain a nanofiltration concentrate and a nanofiltration filtrate;

[0109] Wherein, the nanofiltration treatment includes a primary nanofiltration at a pressure of 7 MPa and a secondary nanofiltration at a pressure of 3.5 MPa, which are performed sequentially;

[0110] (3) using an evaporation crystallization device to evaporate and crystallize the nanofiltration filtrate obtained in step (2) at 106° C. to obtain a mother liquor, sodium chloride crystals and condensed water;

[0111] (4) using a purification unit to perform secondary impurity removal on the mother liquor obtained in step (3) to obtain a lithium chloride solution;

[0112] Wherein, the secondary impurity removal includes double alkali impurity removal; the double alkali impurity removal includes: sequentially mixing sodium hydroxide solution and sodium carbonate into the mother liquor obtained in step (3); and then filtering calcium and magnesium precipitated impurities.

[0113] Example 3

[0114] This embodiment provides a lithium extraction device system for high-grade brine. The lithium extraction device system is different from that of Embodiment 1 only in that:

[0115] In this embodiment, the mesh size of the filter cloth used in the plate and frame filter press is adjusted to 600 meshes; and the pore size of the ceramic membrane in the ceramic membrane separation device 2 is adjusted to 100 nm.

[0116] Example 4

[0117] This embodiment provides a lithium extraction device system for high-grade brine. The lithium extraction device system is different from that of Embodiment 1 only in that:

[0118] In this embodiment, the mesh size of the filter cloth used in the plate and frame filter press is adjusted to 300 meshes; and the pore size of the ceramic membrane in the ceramic membrane separation device 2 is adjusted to 120 nm.

[0119] Example 5

[0120] This embodiment provides a lithium extraction device system for high-grade brine. The lithium extraction device system is different from that of Embodiment 1 only in that:

[0121] In this embodiment, the mesh size of the filter cloth used in the plate and frame filter press is adjusted to 700 meshes; and the pore size of the ceramic membrane in the ceramic membrane separation device 2 is adjusted to 20 nm.

[0122] Example 6

[0123] This embodiment provides a lithium extraction device system for high-grade brine. The lithium extraction device system is different from that of Embodiment 1 only in that:

[0124] In this embodiment, the reverse osmosis device 8 is omitted.

[0125] Example 7

[0126] This embodiment provides a lithium extraction device system for high-grade brine. The lithium extraction device system is different from that of Embodiment 1 only in that:

[0127] In this embodiment, the first multi-stage nanofiltration device 5 is adjusted to a single-stage nanofiltration device.

[0128] The lithium extraction method performed using the lithium extraction device system provided in this embodiment is different from that in Embodiment 1 only in that the secondary nanofiltration process described in step (2) is omitted in this embodiment.

[0129] Example 8

[0130] This embodiment provides a lithium extraction device system for high-grade brine. The lithium extraction device system is different from that of Embodiment 1 only in that:

[0131] In this embodiment, the second multi-stage nanofiltration device is adjusted to a single-stage nanofiltration device.

[0132] The lithium extraction method performed using the lithium extraction device system provided in this embodiment is different from that in Embodiment 1 only in that the secondary nanofiltration impurity removal described in step (4) is omitted in this embodiment.

[0133] Comparative Example 1

[0134] This comparative example provides a lithium extraction device system for high-grade brine, and the lithium extraction device system is different from Example 1 only in that:

[0135] In this comparative example, the purification unit is omitted.

[0136] The lithium extraction method performed by the lithium extraction device system provided in this comparative example is different from that in Example 1 only in that the secondary impurity removal process described in step (4) is omitted in this comparative example.

[0137] Comparative Example 2

[0138] This comparative example provides a lithium extraction device system for high-grade brine, and the lithium extraction device system is different from Example 1 only in that:

[0139] The membrane separation module is omitted in this comparative example, that is, the continuously arranged ceramic membrane separation device 2 and the ceramic membrane water production tank 3 are omitted in this comparative example.

[0140] The lithium extraction method performed by the lithium extraction device system provided in this comparative example is different from that in Example 1 only in that the ceramic membrane filtration process described in step (1) is omitted in this comparative example.

[0141] The ion concentration in the mixed solution obtained after the evaporation and crystallization treatment in step (2) using the methods provided in the above embodiments and comparative examples was detected, and the removal rate of each ion and the recovery rate of lithium ions were calculated. The results are shown in Table 1.

[0142] Table 1

[0143] <![CDATA[Ca 2+ Removal rate / %]]> <![CDATA[Mg 2+ Removal rate / %]]> <![CDATA[Li + Recovery rate / %]]> Example 1 ＞80 ＞98 ＞70 Example 2 ＞80 ＞98 ＞70 Example 7 ＞50 ＞88 ＞70 Example 8 ＞50 ＞88 ＞70 Comparative Example 1 ＞50 ＞88 ＞70 Comparative Example 2 ＞80 ＞98 ＞70

[0144] From Table 1, we can see the following points:

[0145] (1) Comprehensive analysis of Examples 1-2 shows that the lithium extraction device system provided by the utility model can effectively improve the recovery rate of lithium, reduce the dosing cost, operation cost and investment cost of the device system;

[0146] (2) Comprehensive analysis of Example 1 and Examples 3-5 shows that the plate and frame filter press and the ceramic membrane separation device can effectively remove impurities (particles, silt, suspended matter, colloids, etc.) in high-grade brine, ensure the quality of water entering the nanofiltration membrane, and extend the membrane cleaning cycle and service life;

[0147] Comprehensive analysis of Example 1 and Comparative Example 2 shows that omitting the ceramic membrane separation device will not have a significant impact on the recovery and removal of ions in the subsequent lithium extraction process, but impurities in the brine will damage the subsequent nanofiltration membrane, affecting its life, thereby increasing the cost of device maintenance, etc.

[0148] (3) Comprehensive analysis of Example 1 and Example 6 shows that when the reverse osmosis device 8 is omitted, the condensate discharged from the evaporation crystallization device cannot be effectively recovered, resulting in a waste of resources; and pure water cannot be provided to the first multi-stage nanofiltration device, affecting the multi-stage nanofiltration.

[0149] (4) Comprehensive analysis of Example 1 and Examples 7-8 shows that the multi-stage nanofiltration process can better remove impurities in the brine and improve the purity of the lithium chloride solution. It can be seen that multi-stage nanofiltration is one of the important factors for efficient lithium extraction in the utility model;

[0150] (5) Comprehensive analysis of Example 1 and Comparative Example 1 shows that when the purification unit is omitted, the impurity concentration in the mother liquor discharged from the evaporation crystallization device is high, and efficient recovery of lithium ions cannot be achieved. This shows that the purification unit is an indispensable device in the lithium extraction device system provided by the utility model.

[0151] In summary, the lithium extraction device system provided by the utility model improves the lithium recovery rate, reduces the device system dosing, operating costs and device system investment costs; and the lithium extraction device system has a simple structure, simple operation, and has good industrial application prospects.

[0152] The applicant declares that the above is only a specific implementation method of the present utility model, but the protection scope of the present utility model is not limited thereto. The technicians in the relevant technical field should understand that any changes or substitutions that can be easily thought of by the technicians in the relevant technical field within the technical scope disclosed in the present utility model fall within the protection scope and disclosure scope of the present utility model.

Claims

1. A lithium extraction device system for high-grade brine, characterized in that: According to the flow direction of high-grade brine, the lithium extraction device system includes a pretreatment unit, a first multi-stage nanofiltration device, an evaporation crystallization device and a purification unit which are sequentially connected; The pretreatment unit comprises a filter press device and a membrane separation module which are sequentially connected; The purification unit includes a second multi-stage nanofiltration device or a dual-alkali reaction device.

2. The high-grade brine lithium extraction device system according to claim 1, characterized in that: The filter press device comprises a plate and frame filter press; The mesh number of the filter cloth used in the plate and frame filter press is 400 to 600 meshes.

3. The high-grade brine lithium extraction device system according to claim 1, characterized in that: The membrane separation module comprises a ceramic membrane separation device and a ceramic membrane water production tank which are connected and arranged; The pore size of the ceramic membrane in the ceramic membrane separation device is 25-100 nm.

4. The lithium extraction device system for high-grade brine according to claim 3 is characterized in that: A pressure pump is provided between the ceramic membrane water production tank and the first multi-stage nanofiltration device; The first multi-stage nanofiltration device is a two-stage nanofiltration device; The filtrate outlet of the first multi-stage nanofiltration device is connected to an evaporation crystallization device; The concentrated liquid outlet of the first multi-stage nanofiltration device is connected to the salt pan.

5. The high-grade brine lithium extraction device system according to claim 1, characterized in that: The evaporation crystallization device comprises an MVR evaporation crystallization device.

6. The high-grade brine lithium extraction device system according to claim 1, characterized in that: The mother liquid outlet of the evaporation crystallization device is connected to the purification unit; The solid outlet of the evaporation crystallization device is connected to the concentrated liquid outlet of the first multi-stage nanofiltration device; The condensed water outlet of the evaporation crystallization device is connected to the reverse osmosis device.

7. The high-grade brine lithium extraction device system according to claim 6, characterized in that: The outlet of the reverse osmosis device is connected to the inlet of the first multi-stage nanofiltration device through a reverse osmosis water production tank.

8. The high-grade brine lithium extraction device system according to claim 1, characterized in that: The second multi-stage nanofiltration device includes a two-stage nanofiltration device.

9. The high-grade brine lithium extraction device system according to claim 1, characterized in that: The dual-alkali reaction device comprises a reaction pool and a storage tank which are connected in sequence.

10. The high-grade brine lithium extraction device system according to claim 9, characterized in that: The reaction tank is provided with an additive filling port; The mother liquor outlet of the evaporation crystallization device is connected to the inlet of the reaction tank.

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