Continuous fluid separation system for recovering lithium from mirabilite

Abstract

The invention provides a continuous fluid separation system for recovering lithium from mirabilite, and relates to the technical field of continuous fluid separation. A continuous fluid separation system for recovering lithium from mirabilite comprises a plurality of treatment subsystems, each treatment subsystem comprises an exchange area, a material washing area and an acid regeneration analysis area which are arranged in sequence, and each separation unit of the treatment subsystems is filled with a titanium adsorbent filler; the exchange area adopts a three-parallel two-serial feeding mode; gradient washing is carried out in a three-string mode in the material washing area; and the acid regeneration analysis area adopts a three-parallel analysis mode. According to the continuous fluid separation system for recovering lithium from mirabilite, the recovery rate of lithium can exceed 90%, continuous operation is achieved, product components and concentration are kept stable, and the use amount of washing water and an acid regenerant is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of continuous fluid separation and relates to a continuous fluid separation system for recovering lithium from mirabilite. Background Art

[0002] The extraction of lithium salt from spodumene requires transformation calcination, acidification roasting, water leaching and filtration. The leachate is causticized and frozen to separate a large amount of mirabilite (Na2SO4·10H2O). The mirabilite contains a large amount of lithium ions. After it is redissolved, the lithium content in the solution is relatively high (lithium ion content is about 2.5-3.5g / L, accounting for about 20% of the total lithium content). The existing technology mainly uses crystallization to recover this part of lithium. The mirabilite is dissolved, and anhydrous Na2SO4 is separated by evaporation, concentration and crystallization. The crystallization mother liquor (lithium ion content is about 9-10g / L) is returned to the main process freezing process for freezing, and the cycle is repeated. This technology has many problems, such as large material circulation volume and large lithium loss.

[0003] Using titanium-based adsorbent as filler to absorb and separate lithium can effectively separate and recover lithium in solution. Chinese patent CN112777614A discloses a salt lake brine adsorption lithium extraction device, including an adsorption tank, a solid-liquid separator, an analytical column, a first dilute acid addition tank, and a second dilute acid addition tank. Chinese patent CN117926011A adopts an "adsorption + membrane" process for lithium precipitation mother liquor. The adsorption column equipped with titanium-based adsorption resin sequentially passes through four stages of lithium adsorption, brine washing, analytical and acid washing, thereby realizing lithium recovery from lithium precipitation mother liquor.

[0004] The applicant believes that the existing method of recovering lithium by adsorption needs further improvement. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a continuous fluid separation system for recovering lithium from mirabilite.

[0006] The technical solution of the present invention is as follows:

[0007] A continuous fluid separation system for recovering lithium from mirabilite, comprising a plurality of processing subsystems, wherein the processing subsystems comprise an exchange zone, a material washing zone and an acid regeneration and analysis zone arranged in sequence, and each separation unit of the processing subsystems is respectively filled with a titanium-based adsorbent filler;

[0008] The exchange zone adopts a 3-in-2-in-parallel feeding mode;

[0009] The washing area adopts gradient water washing in the form of 3 series;

[0010] The acid regeneration analysis zone adopts a 3-parallel analysis mode.

[0011] Preferably, the plurality of processing subsystems are 2 processing subsystems, and the second processing subsystem repeats the processing flow of the first processing subsystem.

[0012] More preferably, the adsorption tail liquid obtained after the treatment process of the first treatment subsystem is adjusted to pH>14 and then used as the feed raw material for the second treatment subsystem.

[0013] Further preferably, the lithium ion content in the adsorption tail liquid does not exceed 0.8 g / L.

[0014] More preferably, the first separation unit of the exchange zone is fully adsorbed and saturated.

[0015] More preferably, the conductivity of the diluted material washed out by the first separation unit in the washing zone before rotation does not exceed 1000 μs / cm.

[0016] More preferably, the titanium content dissolved by the first separation unit in the acid regeneration and analysis zone is not higher than 3 ppm.

[0017] More preferably, the plurality of processing subsystems are arranged sequentially along the circumferential direction according to the processing flow.

[0018] More preferably, the feed rate of the exchange zone is 4-12 ml / min, the feed rate of the water washing zone is 50-60 ml / min, and the feed rate of the acid regeneration and analysis zone is 6-20 ml / min.

[0019] More preferably, the filling amount of the titanium-based adsorbent filler in each separation unit is 200-300 g.

[0020] The beneficial effects of the present invention are as follows: the present invention adopts continuous fluid separation technology to extract and recover lithium from mirabilite, which effectively improves the total recovery rate of lithium, reduces material consumption, improves product value, and reduces production costs. At the same time, it also has the following characteristics: (1) Due to continuous operation, the product composition and concentration remain stable, which is convenient for supporting applications in downstream processes; (2) The equipment is compact and easy to install, and has low site requirements; (3) Compared with the discontinuous adsorbent adsorption method, the amount of acid regeneration agent and washing water is greatly reduced, and a maximum of 50-60% can be saved; (4) The rotation speed can be automatically adjusted according to the changes in the quality and flow rate of the inflowing fluid according to the needs of the production process, which can ensure operation under the economically optimal state; (5) According to the convenience of the production process, the flow direction of the fluid can be connected into a countercurrent or parallel flow mode; (6) Due to the use of multiple separation units, the production method process can be flexibly changed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the continuous fluid separation system for recovering lithium from mirabilite of Example 1. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further illustrated and described below through specific implementation methods.

[0023] The present invention provides a continuous fluid separation system for recovering lithium from mirabilite, comprising a plurality of processing subsystems, wherein the processing subsystems comprise an exchange zone, a material washing zone and an acid regeneration and analysis zone arranged in sequence, and each separation unit of the processing subsystem is respectively filled with a titanium-based adsorbent filler;

[0024] The exchange zone adopts a 3-in-2-in-1 feeding mode to adsorb lithium ions in the mirabilite. The mirabilite raw material liquid first enters the first set of parallel columns to fully contact with the titanium-based adsorbent to minimize the content of lithium ions in the outflow tail liquid;

[0025] The washing area adopts a gradient water washing in the form of 3 series; after the sodium sulfate is exchanged with the titanium adsorbent, the adsorbent loses its exchange capacity, so the adsorbent needs to be regenerated and analyzed. Since there is still sodium sulfate stock solution remaining in the separation unit, the raw materials in the separation unit need to be washed out;

[0026] The acid regeneration analysis area adopts a 3-parallel analysis mode to ensure that the residence time of the analytical acid is long enough, while reducing the amount of acid used and increasing the product concentration.

[0027] The present invention adopts a continuous fluid separation system to separate and recover lithium from Glauber's salt, which can effectively recover lithium from Glauber's salt. Continuous production can keep product composition and concentration stable, and the amount of acid regeneration agent and washing water used is greatly reduced.

[0028] In a preferred embodiment of the present invention, the plurality of processing subsystems are two processing subsystems, and the second processing subsystem repeats the processing flow of the first processing subsystem. One processing subsystem of the present invention can include 15 separation units, and the entire system can include 30 separation units. By using two processing subsystems, the adsorption tail liquid obtained after the sodium sulfate solution containing lithium is treated by the first processing subsystem also contains a certain amount of lithium ions, and then after passing through the second processing subsystem, the lithium can be further separated and recovered, thereby improving the recovery rate of lithium. After recovery by the two processing subsystems, the recovery rate of lithium can exceed 90%.

[0029] More preferably, the adsorption tail liquid obtained after the treatment process of the first treatment subsystem is adjusted to pH>14 and used as the feed raw material of the second treatment subsystem. The adsorption tail liquid also contains a certain amount of lithium ions, and adding alkali to adjust the pH>14 is more conducive to the recovery of the second treatment subsystem. In the present invention, the alkali can be a sodium hydroxide solution, which can avoid the introduction of other impurities.

[0030] Further preferably, the lithium ion content in the adsorption tail liquid does not exceed 0.8 g / L. In the present invention, the recovery rate of lithium ions in the mirabilite solution after passing through the first processing subsystem can reach about 75%. For example, the lithium ion content in the raw mirabilite solution can be 2-3 g / L, and the lithium ion content in the adsorption tail liquid after recovery by the first processing subsystem can be about 0.4-0.75 g / L.

[0031] In a more preferred embodiment of the present invention, the first separation unit of the exchange zone is fully adsorbed and saturated. The test method for full adsorption saturation is: take an instantaneous sample of the exchange resin of the first separation unit before rotation and detect the lithium content therein, when the detected lithium content is close to that of the mirabilite raw material solution (for example, if the lithium ion content in the mirabilite raw material solution is 2.5 g / L, the detected lithium content can be (2.5±0.1) g / L), it means that the separation column of the separation unit is adsorbed and saturated.

[0032] In a more preferred embodiment of the present invention, the conductivity of the diluted material washed out by the first separation unit in the washing zone before rotation does not exceed 1000 μs / cm. The purpose of washing is to remove the sodium sulfate adsorbed by the separation column of the separation unit. When the conductivity of the diluted material washed out by water does not exceed 1000 μs / cm, it is considered that the washing is complete and the adsorbed sodium sulfate has been completely removed.

[0033] In a more preferred embodiment of the present invention, the titanium content dissolved by the first separation unit of the acid regeneration analysis zone is not higher than 3ppm, which can avoid excessive analysis of the adsorbent causing dissolution of the exchange resin and affecting the subsequent adsorption of lithium ions. In the present invention, the acid used in the acid regeneration analysis zone can be a sulfuric acid solution, a hydrochloric acid solution, etc., and the concentration of the acid can be 0.01-0.03mol / L.

[0034] In a more preferred embodiment of the present invention, several processing subsystems are arranged in sequence along the circumferential direction according to the processing flow. For example, the continuous fluid separation system for recovering lithium from mirabilite of the present invention comprises 30 separation units and 2 processing subsystems, the first processing subsystem comprises a first exchange zone, a first washing zone and a first acid regeneration and analysis zone, and the second processing subsystem comprises a second exchange zone, a second washing zone and a second acid regeneration and analysis zone, then the first exchange zone, the first washing zone, the first acid regeneration and analysis zone, the second exchange zone, the second washing zone and the second acid regeneration and analysis zone are arranged in sequence along the circumferential direction.

[0035] In a more preferred embodiment of the present invention, the feed rate of the exchange zone is 4-12 ml / min, the feed rate of the water washing zone is 50-60 ml / min, and the feed rate of the acid regeneration and analysis zone is 6-20 ml / min. For example, the feed rate of the exchange zone can be any value among 4ml / min, 5ml / min, 6ml / min, 7ml / min, 8ml / min, 9ml / min, 10ml / min, 11ml / min, 12ml / min, etc. or any value in between, the feed rate of the water wash zone can be any value among 50ml / min, 51ml / min, 52ml / min, 53ml / min, 54ml / min, 55ml / min, 56ml / min, 57ml / min, 58ml / min, 59ml / min, 60ml / min, etc. or any value in between, and the feed rate of the acid regeneration and analysis zone can be any value among 6ml / min, 8ml / min, 10ml / min, 12ml / min, 14ml / min, 16ml / min, 18ml / min, 20ml / min, etc. or any value in between.

[0036] In a more preferred embodiment of the present invention, the filling amount of the titanium adsorbent filler in each separation unit is 200-300g. For example, the filling amount can be any value of 200g, 210g, 220g, 230g, 240g, 250g, 260g, 270g, 280g, 290g, 300g, etc. or any value in between. In the present invention, there is no particular limitation on the titanium adsorbent, and it can be directly obtained from commercially available products, such as JW-LTOS, G-200, KJT-0X1, etc. The titanium adsorbent filler can be added with water to prepare a dispersion before use, and the density of the dispersion is controlled not to exceed 0.8g / ml.

[0037] The technical solution of the present invention is further described and illustrated according to various embodiments below.

[0038] Example 1

[0039] The continuous fluid separation system for recovering lithium from mirabilite of this embodiment is shown in the attached Figure 1 As shown, it includes 30 separation units with a designed processing capacity of 0.9L / h. The titanium-based adsorbent is JW-LTOS. The titanium-based adsorbent filling amount of the exchange column of each separation unit is 312.5ml (the density of the titanium-based adsorbent is 0.7g / ml), among which 5#, 6#, 20# and 21# separation columns are immersion waiting columns.

[0040] The continuous fluid separation system for recovering lithium from mirabilite is divided into the following sections:

[0041] The following 1)-3) segmented areas are for primary lithium extraction.

[0042] 1) Primary exchange area (10-15# separation units)

[0043] This area uses a 3-in-2-in-1 feeding mode to adsorb lithium ions from mirabilite. 3.8L mirabilite solution (lithium ion concentration is 2.25g / L) first enters the first set of parallel exchange columns, fully contacts with the titanium adsorbent, and the tail liquid containing some lithium ions flows out and enters the subsequent parallel exchange columns for adsorption, which can ensure that the final adsorption tail liquid contains as few lithium ions as possible. In order to ensure the utilization rate of the adsorbent, the first exchange column of the feed is fully adsorbed and saturated. Therefore, an instantaneous sample of the first exchange column is taken before the exchange column rotates to detect the lithium content. When it is close to the raw material solution (for example, the lithium content is 2.2g / L), it means that the exchange column is saturated with adsorption.

[0044] 2) Primary washing area (7-9#, 1#)

[0045] After the sodium sulfate is exchanged with the titanium-based adsorbent, the adsorbent loses its exchange capacity, so the adsorbent needs to be regenerated and analyzed. Since there is sodium sulfate stock solution remaining in the exchange column, the sodium sulfate raw material in the exchange column needs to be washed out. The washing area uses a gradient water washing in the form of 3 series, and the diluted material washed out is re-loaded on the column to ensure the final product yield. In order to ensure the quality of the separated lithium compound product, it is necessary to detect whether the water washing is clean. Take an instantaneous sample of the first exchange column before rotation, and detect the conductivity (less than 1000μs / cm) to determine whether the water washing is complete.

[0046] 3) Primary acid regeneration analysis area (2-4#)

[0047] This area uses 3 and 100% elution, and uses sulfuric acid with a concentration of g / L to ensure that the residence time of the analytical acid is long enough, while reducing the amount of sulfuric acid and increasing the product concentration. In order to avoid excessive analysis of the adsorbent and resulting in loss of exchange resin, the titanium content dissolved from the first exchange column in the analytical area needs to be regularly tested (not higher than 3ppm).

[0048] The following 4)-6) segmented areas are secondary lithium extraction, and the secondary lithium extraction is to repeat the primary lithium extraction process, and the pH of the primary adsorption tail liquid is adjusted to > 14 and then used for secondary adsorption.

[0049] 4) Secondary exchange area (25-30#)

[0050] The feed is the adsorption tail liquid after the first feed adsorption (lithium ion concentration 0.5g / L). This area adopts a 3-in-2 series feed mode to adsorb lithium ions in the tail liquid. The tail liquid first enters the first set of parallel exchange columns, fully contacts with the titanium adsorbent, and the secondary tail liquid containing some lithium ions flows into the subsequent parallel exchange columns for further adsorption, which can ensure that the lithium ions in the secondary tail liquid are as small as possible. When the lithium ion content in the secondary tail liquid does not exceed 0.1g / L, the secondary tail liquid is adsorbed waste liquid and discharged to the waste liquid station.

[0051] 5) Secondary washing area (22-24#, 16#)

[0052] After the above-mentioned adsorption tail liquid is exchanged with the titanium-based adsorbent, the adsorbent loses its exchange capacity, so the adsorbent needs to be regenerated and analyzed. Since there is still sodium sulfate remaining in the exchange column, the sodium sulfate in the exchange column needs to be washed out. The water washing area adopts a gradient water washing in the form of 3 series, and the diluted material washed out is re-loaded on the column to ensure the final product yield. In order to ensure the quality of the product, it is necessary to detect whether the water washing is clean. Take an instantaneous sample of the first exchange column before rotation, and test the conductivity to determine whether the water washing is complete. When the conductivity measured by sampling does not exceed 1000μs / cm, the water washing is complete.

[0053] 6) Secondary acid regeneration analysis area (17-19#)

[0054] This area uses 3-string analysis, using sulfuric acid with a concentration of 0.02 mol / L to ensure that the residence time of the analytical acid is long enough, while reducing the amount of acid used and increasing the product concentration. In order to avoid excessive analysis of the adsorbent and resulting in resin loss, the titanium content of the first exchange column in the analysis area needs to be regularly tested.

[0055] In this embodiment, the raw material is 3.8L of mirabilite solution, and the lithium ion concentration is 2.25g / L; the volume of the adsorption waste liquid after the secondary lithium extraction is 3.8L, and the lithium ion concentration is 0.09g / L; the washing liquid of the secondary washing material is 5.8L, and the lithium ion concentration is 0.06g / L; the product obtained after the secondary acid regeneration analysis is 14.9L, and the lithium ion concentration is 0.52g / L. The positive yield of the product is measured to be 90.62%, and the reverse yield is 91.93%.

[0056] Example 2

[0057] The difference between this embodiment and embodiment 1 is that the raw material is 3.56 L of mirabilite solution and the lithium ion concentration is 2.19 g / L. The other steps remain unchanged.

[0058] The volume of the adsorption waste liquid after the secondary lithium extraction was 3.56L, and the lithium ion concentration was 0.07g / L; the washing liquid of the secondary washing material was 5.5L, and the lithium ion concentration was 0.06g / L; the product obtained after the secondary acid regeneration analysis was 14.6L, ​​and the lithium ion concentration was 0.49g / L. The positive yield of the product was measured to be 91.76%, and the reverse yield was 92.57%.

[0059] Example 3

[0060] The difference between this embodiment and embodiment 1 is that the raw material is 3.6 L of mirabilite solution and the lithium ion concentration is 2.72 g / L. The other steps remain unchanged.

[0061] The volume of the adsorption waste liquid after the secondary lithium extraction was 3.6L, and the lithium ion concentration was 0.11g / L; the washing liquid of the secondary washing material was 5.1L, and the lithium ion concentration was 0.09g / L; the product obtained after the secondary acid regeneration analysis was 14.6L, ​​and the lithium ion concentration was 0.61g / L. The positive yield of the product was measured to be 90.95%, and the reverse yield was 91.27%.

[0062] As described above, the basic principles, main features and advantages of the present invention are shown and described. Those skilled in the art should understand that the present invention is not limited by the above embodiments, which are only preferred embodiments of the present invention and cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the scope of the present invention and the content of the specification should still be within the scope of the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents.

Claims

1. A continuous fluid separation system for recovering lithium from mirabilite, characterized in that: It comprises several processing subsystems, wherein the processing subsystem comprises an exchange zone, a material washing zone and an acid regeneration and analysis zone arranged in sequence, and each separation unit of the processing subsystem is respectively filled with a titanium-based adsorbent filler; The exchange zone adopts a 3-in-2-in-parallel feeding mode; The washing area adopts gradient water washing in the form of 3 series; The acid regeneration analysis zone adopts a 3-parallel analysis mode.

2. The continuous fluid separation system for recovering lithium from sodium sulfate according to claim 1, characterized in that: The plurality of processing subsystems are two processing subsystems, and the second processing subsystem repeats the processing flow of the first processing subsystem.

3. The continuous fluid separation system for recovering lithium from sodium sulfate according to claim 2, characterized in that: The adsorption tail liquid obtained after the treatment process of the first treatment subsystem is adjusted to pH>14 and then used as the feed raw material for the second treatment subsystem.

4. The continuous fluid separation system for recovering lithium from sodium sulfate according to claim 3, characterized in that: The lithium ion content in the adsorption tail liquid does not exceed 0.8 g / L.

5. The continuous fluid separation system for recovering lithium from sodium sulfate according to claim 1, characterized in that: The first separation unit of the exchange zone is fully adsorbed and saturated.

6. The continuous fluid separation system for recovering lithium from sodium sulfate according to claim 1, characterized in that: The conductivity of the diluted material washed out by the first separation unit in the material washing area before rotation does not exceed 1000 μs / cm.

7. The continuous fluid separation system for recovering lithium from sodium sulfate according to claim 1, characterized in that: The titanium content dissolved out of the first separation unit in the acid regeneration and analysis zone is not higher than 3 ppm.

8. The continuous fluid separation system for recovering lithium from sodium sulfate according to claim 1, characterized in that: The plurality of processing subsystems are arranged in sequence along the circumferential direction according to the processing flow.

9. The continuous fluid separation system for recovering lithium from sodium sulfate according to claim 1, characterized in that: The feed rate of the exchange zone is 4-12 ml / min, the feed rate of the water washing zone is 50-60 ml / min, and the feed rate of the acid regeneration and analysis zone is 6-20 ml / min.

10. The continuous fluid separation system for recovering lithium from sodium sulfate according to claim 1, characterized in that: The filling amount of the titanium-based adsorbent filler in each separation unit is 200-300 g.

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