Apparatus for kinetic separation of magnesium salts from brine containing magnesium and lithium by means of a multichannel nozzle

Abstract

The invention relates to a device for kinetic separation of magnesium salts from brine containing magnesium and lithium by means of a multi-channel nozzle. This separation must be carried out because lithium can be extracted economically from brine only when the magnesium / lithium ratio in the mixture reaches a certain extent. This means that the content of magnesium salts must be below a certain concentration limit for lithium. In order to achieve this also in salt lake brine where the magnesium / lithium ratio is very unfavorable, the magnesium must be removed from the mixture as much as possible while the resulting loss of lithium is limited to a minimum. The nozzle according to the invention has concentric liquid flows which contact within a range of milliseconds, thus promoting a faster reaction. This is the precipitation reaction of magnesium when lithium and magnesium are precipitated simultaneously. By means of the nozzle precipitation, magnesium is precipitated selectively and removed from the system as a solid, while most of the lithium remains in the liquid.

Description

Technical Field

[0001] This invention relates to an apparatus for separating magnesium salts from magnesium- and lithium-containing brine using a multi-channel nozzle. This separation is necessary because lithium can only be economically extracted from the brine when the magnesium / lithium ratio in the mixture reaches a certain level. This means that the magnesium salt content must be below a specific concentration limit for lithium. To achieve this also in lake brine where the magnesium / lithium ratio is very unfavorable, as much magnesium as possible must be removed from the mixture while minimizing the resulting lithium loss. Background Technology

[0002] To this end, the drastically different precipitation rates of magnesium and lithium in brine are utilized. A specific nozzle with concentric liquid flow and a liquid flow contact time of several milliseconds both facilitate a faster reaction. When lithium and magnesium precipitate simultaneously, it is a magnesium precipitation reaction. Through nozzle precipitation, magnesium is selectively precipitated and removed from the system as a solid, while most of the lithium remains in the liquid. This significantly alters the magnesium / lithium ratio in the brine, making lithium dominant, thus enabling the mining of lithium deposits that are currently uneconomical to extract using conventional methods.

[0003] Lithium is one of the key elements for economic transformation in the coming years, not only because of its crucial role in manufacturing high-quality batteries. Therefore, demand for lithium is expected to continue to grow in the coming years, while resources remain relatively limited.

[0004] Currently, lithium is mainly extracted from ore or brine. Extraction from ore is relatively simple. However, it involves very high chemical consumption, causing serious environmental impacts. Furthermore, globally exploitable lithium deposits are extremely limited.

[0005] Extracting lithium from salt lakes, i.e., natural salt lakes, is a sustainable alternative. Although there are many salt lakes globally with relatively high salt and lithium content, lithium can only be extracted from specific lakes. This is because these lakes have high magnesium content and low lithium content, requiring complex separation steps that result in significant lithium loss and a high proportion of solid waste. This is primarily due to the high magnesium content of lithium. + and Mg ++ The ionic radii of these molecules are almost identical, resulting in very similar physical and chemical properties, rendering traditional separation methods ineffective. Since each ton of Li₂CO₃ requires more than 500 m³ of [resource / material], [further separation is necessary]. 3 The area lacks fresh water, and the region often faces water shortages, making the situation even more severe.

[0006] This situation necessitates an urgent need for an effective, economical, and environmentally friendly method to separate magnesium from the brine of natural salt lakes while minimizing lithium loss.

[0007] According to existing technology, lithium is currently extracted from salt lakes through an evaporation-precipitation process. For this purpose, the brine is first introduced into a series of solar-powered evaporation tanks to precipitate sodium and potassium. The remaining brine is then treated with calcium oxide in another tank. As a result, magnesium precipitates out as solid magnesium hydroxide, while the lithium salt remains in solution. However, non-specific reactions in the tanks lead to significant lithium loss, approximately 50%. The remaining Li-rich... + The liquid was then diluted and transported to another Li + / Mg ++ The separation unit consists of multiple adsorption and multi-stage nanofiltration processes. The brine is further purified and concentrated through a reverse osmosis stage and a subsequent evaporation stage, and then lithium is finally precipitated as lithium carbonate by the addition of Na₂CO₃. Clearly, if the original brine contains Mg… ++ / Li + If the ratio is unfavorable, the high lithium loss will quickly make this process uneconomical. Therefore, the Mg content must be adjusted beforehand. ++ / Li + The ratio, making it favorable to Li + At the same time, minimize the Li during the downstream separation process. + The loss.

[0008] Publication: “Sustainable extraction of lithium from brine with simultaneous production of magnesium hydroxide” by Yong, M., Tang, M., Sun, L. et al. (Nature Sustainability 10 / 2024) describes a nanofiltration process using ethylenediaminetetraacetic acid (EDTA) for the direct and efficient extraction of Li from brine. + And effectively precipitate Mg ++ In this process, Mg is first precipitated using EDTA. ++ The remaining brine is then processed further in a conventional manner as much as possible. While this process is certainly feasible on a laboratory scale, it may be uneconomical on a technical scale, given the relatively high amount of EDTA required. Furthermore, according to the publication, the use of EDTA for pretreatment of natural lake water in a natural environment would have a very significant environmental impact.

[0009] DE 10 2010 019 554 A1 describes a method for simultaneously enriching lithium and depleting magnesium from a high-chloride solution. This is achieved by adding potassium chloride to the salt solution, thereby precipitating a potassium magnesium salt (KMgCl3·6H2O). This tilts the magnesium-to-lithium ratio towards lithium. The disadvantages are: the need for large amounts of potassium chloride, the energy consumption of decomposing potassium carnallite back into potassium chloride, and the energy consumption for regeneration. The process is also based on purely chemical steps, and reaction kinetics play no role.

[0010] US 8691169 describes a method for extracting metallic lithium from natural or industrial salt solutions. The method includes the following steps: (i) precipitation of magnesium with calcium hydroxide; (ii) removal of boron by solvent extraction; (iii) precipitation of lithium with sodium carbonate; (iv) conversion of lithium carbonate to lithium bicarbonate using carbon dioxide; and (v) decomposition of lithium bicarbonate into high-purity lithium carbonate by heating the solution. Different reaction rates are not important here, as precipitation occurs in a pool or tank. This is because the reaction is highly unspecific and yields a large amount of precipitated Li. + Therefore, it is expected that Li + The losses will be significant.

[0011] US 11634789 describes a method for selectively recovering lithium from a salt solution using a water redox reaction. Lithium extraction is carried out via a lithium reducing agent in the form of ferric phosphate solids, either as a trivalent iron heteropolymer (Eisen(III)-Heterosit) or ferric phosphate. The separated lithium-containing ferric phosphate solids are then mixed with an oxidant in the form of lithium iron(II) phosphate (Lithiumeisen(II)-Triphylit), which re-oxidizes the separated lithium. This yields a pure lithium(I) solution. A drawback of this method is the necessity of using both a reducing agent and an oxidant to separate lithium, resulting in a complex process requiring numerous steps.

[0012] WO2016 / 193087 describes a method for manufacturing small particles synthesized in a continuous process, the size of which can be precisely controlled during the process. This is achieved through a specific nozzle at which two reactants come into contact with each other, thereby forming tiny particles. The particle size depends primarily on the flow parameters of the liquid at the nozzle exit. This invention focuses on obtaining as many particles as possible with the smallest possible diameter (nanoparticles) and the narrowest possible particle size distribution.

[0013] EP2023 / 053468 describes a method and technical process for extracting high-magnesium-content particles from seawater. These particles can be magnesium hydroxide or other water-insoluble magnesium salts, such as magnesium sulfate, magnesium carbonate, etc. These particles are prepared using a suitable alkaline reagent during precipitation. The size and yield of the obtained particles can be influenced to some extent by using a specially designed nozzle structure and / or adding auxiliary reagents for precipitation. The sole objective here is to obtain a large quantity of particles (e.g., magnesium hydroxide). The issue of maximizing the concentration of certain substances in the wastewater is not addressed here. There is also no evidence that differences in reaction rates can be used to separate specific substances from a mixture. Summary of the Invention

[0014] Based on the above, the object of the present invention is to provide an improved apparatus for separating magnesium salts from magnesium and lithium brine, which avoids the use of conventional and environmentally harmful separation methods.

[0015] The object of the present invention is achieved by means of the apparatus according to the independent claim, wherein the dependent claims at least represent a suitable design and improvement. Attached Figure Description

[0016] Figure 1 and Figure 3 Partial and complete cross-sectional views of the nozzle body are shown, including the feed inlets of reactant 1 (R1) and reactant 2 (R2), the liquid channel (FK) of the precipitated product (FP), and the corresponding central tube (RC) within the corresponding liquid channel (FK).

[0017] Figure 2 This is a realistic image of the nozzle module according to the present invention, showing the actual reaction zone (RZ) outside the nozzle body. Invention Details

[0019] The method described according to the present invention is based on the fundamental concept that magnesium and lithium salts in a salt mixture in a salt lake precipitate at different rates. This effect is utilized by using a specific nozzle for precipitation. The nozzle is designed such that the reaction between the brine and the precipitant does not occur throughout the entire liquid volume, but only at the interface between two concentric liquid flows. This triggers a so-called interfacial reaction.

[0020] In reactions occurring throughout a full volume (e.g., a liquid tank), the contact time of the reactants is very long. This allows both fast and slow reactions to proceed. The situation is different for interfacial reactions. Literature indicates that precipitation reactions occurring as interfacial reactions exhibit strong product specificity. This is because the selectivity of the reaction depends primarily on kinetic parameters, as the contact time of the reactants can remain very short in these reactions. This means that the product that reacts faster will always be produced. According to the present invention, this results in highly selective precipitation, favoring the precipitation of magnesium.

[0021] Unlike all known interfacial sedimentation devices that employ parallel liquid channels, this invention utilizes a concentric liquid flow generated by a specific nozzle. Devices with parallel liquid channels can be used in so-called microreactors, but are unsuitable for high flow rates due to their significant pressure loss. The concentrically arranged channels in the nozzle offer the advantages of achieving very high flow rates and low pressure loss in a relatively simple structure, making the nozzle suitable for large-scale technological applications.

[0022] According to the present invention, the flow rates of the two liquid streams in the nozzle are selected such that the contact time is in the range of milliseconds, for example, 0.5-6000 milliseconds. This facilitates a faster reaction.

[0023] This is a magnesium precipitation reaction. The precipitate, as a solid, can be separated and removed from the system, while most of the lithium remains in the liquid.

[0024] By altering the magnesium / lithium ratio in the brine to make it more lithium-friendly, lithium deposits that were previously uneconomical to mine using traditional methods can now be utilized.

[0025] The nozzle configuration according to the present invention can also achieve high liquid flow rates of up to hundreds of m³ / h, while the pressure caused by the nozzle is reduced to one bar to only a few bar, which makes the entire process suitable for large-scale industrial applications.

[0026] According to the present invention, the nozzle is designed as a multi-nozzle head, consisting of multiple individual modules, for example, each module having 16 liquid channels, such as... Figures 1 to 3 As shown.

[0027] Unlike known nozzle devices, these nozzles are optimized for very high flow rates by altering their internal dimensions and geometry. Furthermore, multi-head devices can be connected into assemblies, further increasing the overall liquid throughput.

[0028] The structure of each module described above is as follows: A small tube, several millimeters long, is located at the center of multiple vertical cylindrical channels. The inner diameter of the small tube and the free cross-sectional diameter of the cylindrical channels are both several millimeters. A reaction liquid flows through each small tube and cylindrical channel (see...). Figure 1 and Figure 3 ).

[0029] By design, the two liquid flows are prevented from contacting inside the nozzle, and only at the outlet outside the nozzle. This prevents the nozzle channel from becoming clogged.

[0030] Figure 2 An exemplary photograph of the above module application is shown.

[0031] The turbidity of the liquid jet indicates that the reaction (i.e., precipitation) occurs outside the nozzle. The cross-sectional dimensions of the fluid flow are relatively uniform and chosen so that even in laminar flow conditions, the flow rate per channel can reach tens of liters per minute. The cylindrical channels and their internal tubes are interconnected within the nozzle via horizontal channels to ensure that the fluid conditions in each channel and tube are as similar as possible. Changing the pressure of the two liquids flowing through this nozzle alters the flow parameters, particularly their flow velocities through the tubes and vertical cylindrical channels. This allows adjustment not only of the contact time but also of the mixing ratio between the liquids.

[0032] From a chemical perspective, the precipitation process via the nozzle is as follows. The main reactions listed below occur. In all cases, Mg is used. ++ and Li + Salt solutions (hereinafter typically represented as MgCl2 and LiCl). Solutions of NaOH or Ca(OH)2 or other alkaline reagents can be used as precipitants.

[0033] Example A: Using NaOH solution as a precipitant:

[0034]

[0035] Example B: Using Ca(OH)₂ solution as a precipitant:

[0036]

[0037] In both cases, V1 > V2

[0038] Because Ca(OH)2 has low solubility in water and the pH of the solution is lower than that of NaOH, using NaOH can achieve better results.

[0039] Both Mg(OH)₂ and LiOH are solid substances. However, the concentration of the precipitant and the flow rate in the nozzle are chosen such that the amount of Mg in the system... ++ The ions were always in a slight excess state. This was due to Mg... ++ The precipitation reaction rate is higher than that of Li + The precipitation reaction rate is high, therefore it reacts with Mg ++ The reaction will consume all the precipitant. Therefore, with Li + The reaction cannot occur, and it remains in solution. Meanwhile, Mg... ++ It will then precipitate out as a solid and can be removed from the system by gravity or filtration. In this way, the remaining brine is removed by Li... + Enrichment can then be performed using traditional methods for further processing.

[0040] If the process is carried out in such a way that the precipitant in the system is slightly in excess, then Mg ++ Almost all of it will precipitate out. Because the unreacted precipitant remains in the suspension, it will cause some of the Li to precipitate out. + Precipitation, thus leading to Li + Losses. However, these losses can be minimized by precisely adjusting the reaction ratios to meet stoichiometric requirements.

[0041] In this context, it is recommended that, upon obtaining Li +The method described in this paper is applied to two stages in the process: at the beginning of the process, with the help of insufficient precipitant (Mg) ++ Excessive amounts are used to affect Mg. ++ / Li + The proportion, and in the process itself, after eliminating other salts, used to remove additional residual Mg. ++ In this case, Li + The loss is significantly lower than that of the conventional process described in the background art, the latter's Li + The loss rate is 50%. Therefore, compared with traditional processes, the process described in this paper can achieve significantly higher Li-values ​​under any circumstances. + Yield.

[0042] To precipitate more Mg ++ The remaining brine can be further treated using gelling solutions, which will react with Mg. ++ It forms a separable solid gel, while Li + They remain in the solution. These types of gelling agents include polyanionic substances, such as polysaccharides like carboxymethyl cellulose, cellulose sulfate, alginate, pectin, etc., or polyacrylic acid and similar reagents.

[0043] The following reactions occur during this process:

[0044]

[0045] Such gels can also be immobilized on a carrier. They can usually be redissolved and recovered by adding a large amount of monovalent ionic salt (e.g., NaCl) or by applying a highly alkaline pH.

[0046] The following two examples illustrate this. Detailed Implementation

[0047] Example 1:

[0048] Precipitate with NaOH:

[0049] The brine used has the same composition as that of salt lake water, with a Mg / Li molar ratio of approximately 18:1.

[0050] Lithium chloride 1.28 g / L

[0051] Magnesium chloride hexahydrate 109.58 g / L

[0052] Calcium chloride 1.66 g / L

[0053] Potassium chloride 13.35 g / L

[0054] Sodium chloride 214.29 g / L

[0055] The brine was pumped through the nozzle channel as described. NaOH solution was pumped in as a precipitant through the second channel of the nozzle. The resulting solids were separated. First, the Mg content in the natural brine was determined. ++ and Li + The concentration ratio was determined, and then the concentration ratio in the resulting brine was measured.

[0056] result:

[0057] The new Mg / Li molar ratio is approximately 6:1. Meanwhile, Li... + The loss is less than one percent.

[0058] Example 2:

[0059] Precipitate with Ca(OH)2:

[0060] A brine solution with the same composition as salt lake water was used, with a Mg / Li molar ratio of 18:1.

[0061] Lithium chloride 1.28 g / L

[0062] Magnesium chloride hexahydrate 109.58 g / L

[0063] Calcium chloride 1.66 g / L

[0064] Potassium chloride 13.35 g / L

[0065] Sodium chloride 214.29 g / L

[0066] The brine was pumped through the nozzle channel as described. NaOH solution was pumped in as a precipitant through the second channel of the nozzle. The resulting solids were separated. First, the Mg content in the natural brine was determined. ++ and Li + The concentration ratio was determined, and then the concentration ratio in the resulting brine was measured.

[0067] result:

[0068] The new Mg / Li molar ratio is approximately 12:1. Meanwhile, Li... + The loss is approximately 4%.

[0069] In both cases, further optimization can yield even better results. Furthermore, multiple nozzle cycles can further improve the results.

[0070] When using a suitable precipitant, the same method can also be employed, namely, using the nozzle of the present invention to remove residual Li in the system. + Using Li₂CO₃ or other high-purity water-insoluble Li +It precipitates out in the form of a compound.

[0071] Figure 1 and Figure 3 Partial and complete cross-sectional views of the nozzle body are shown, including the feed inlets of reactant 1 (R1) and reactant 2 (R2), the liquid channel (FK) of the precipitated product (FP), and the corresponding central tube (RC) within the corresponding liquid channel (FK).

[0072] Figure 2 This is a realistic image of the nozzle module according to the present invention, showing the actual reaction zone (RZ) outside the nozzle body.

Claims

1. An apparatus for kinetic separation of magnesium salts from magnesium and lithium-containing brine, especially brine, via a multi-channel nozzle, the apparatus utilizing the different reaction rates of magnesium and lithium precipitation reactions to reduce the magnesium content in the relevant brine, wherein the interfacial reaction is achieved by utilizing the interfacial reaction and brief contact time at the interface surface of the two liquid flows formed by the brine and the precipitant, and further by a nozzle device that provides concentric liquid flows.

2. The apparatus according to claim 1, Its features The nozzle is designed such that the reaction between the brine, especially the brine, and the precipitant occurs only at the contact surface of the concentric liquid flows.

3. The apparatus according to claim 1 or 2, Its features The flow velocity of the liquid in each nozzle ensures that the fluid contact time is several milliseconds.

4. The apparatus according to any one of the preceding claims, Its features The nozzle is implemented as a multi-nozzle head, consisting of multiple individual modules with multiple liquid channels (FK), wherein the liquid flow only comes into contact in the reaction zone (RZ) outside the nozzle.

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