Sorbent for recovering lithium from lithium-containing solutions and method for producing same

Abstract

Proposed are a method for producing a granular sorbent for recovering lithium from lithium-containing solutions, and a sorbent produced using said method. The method includes mixing a chlorine-containing form of an aluminium-lithium double hydroxide with a binder in the form of an aqueous solution of polyvinyl alcohol or an aqueous solution of water-soluble cellulose derivatives, drying, granulating, and heat treating the granules in stages. The invention makes it possible to provide a set of sorbent characteristics that remain at a high level during use, such as strength, dynamic capacity, average lithium concentration in the eluate, how efficiently the sorbent can be washed of contaminants, and the lithium purity of the eluate.

Description

[0001] SORBENT FOR EXTRACTING LITHIUM FROM LITHIUM-CONTAINING SOLUTIONS AND A METHOD FOR ITS PRODUCTION

[0002] Field of technology

[0003] The invention relates to the field of selective extraction of lithium from lithium-containing solutions, both from natural brines containing lithium and from other solutions containing lithium, for example, obtained as a result of processing lithium-containing components. In particular, the invention relates to a sorbent based on a chlorine-containing variety of double aluminum and lithium hydroxide (DGAL-C1), a method for its production and use.

[0004] Prior art

[0005] Due to its lightness and high electrochemical potential, lithium has found wide application in the production of efficient energy storage devices (batteries, accumulators) for electronic products, as they have a high energy density.

[0006] The development of the battery industry for portable electronics (smartphones, laptops, tablets) has led to an increase in the consumption of lithium products. Thus, since the mid-2000s, their consumption has increased by 11% per year.

[0007] However, the rapid development of the electric vehicle industry and a significant increase in global sales of electric vehicles have led to a stable and high demand for lithium-ion batteries. Thus, in 2019, the demand for lithium reached 175.5 thousand tons of LCE (lithium carbonate equivalent), which is 60% of the total lithium consumption.

[0008] The main commercial form of lithium on the market is lithium carbonate (Li2CO3), and today the share of consumption of battery lithium carbonate has reached almost 50% of the total consumption of lithium products and is expected to grow more than 5 times by the end of the current decade.

[0009] Approximately 80% of lithium chloride, lithium carbonate and their derivatives are obtained from lithium, which is extracted from natural brines (formation waters of oil fields, underground brines, geothermal springs, chloride-magnesium, calcium, sodium, potassium brines, sulfate-magnesium, sodium, potassium brines and others, including their combinations). Traditionally, lithium is extracted from the above types of brines in halurgic processes of evaporation in the sun, but such processes are not always effective enough, especially in geographical locations with few sunny days per year or a large amount of annual precipitation, especially for brines with a relatively low lithium content. Alternative extraction methods include sorption, extraction and membrane technologies. At the same time, today it is sorption methods that are most preferred due to their technological advantages and environmental friendliness.The present invention is applicable to the extraction of lithium from both these natural brines and other similar natural sources.

[0010] Natural brines may contain various ions dissolved in them, in particular alkali and alkaline earth metals such as lithium (Li), sodium (Na), potassium (K), magnesium (Mg), and also some transition metals such as manganese, lead, silver and zinc, in various concentrations, as well as other elements or other impurities: boron, sulfates, arsenates, silicon in the form of silicic acids, phosphates, which is determined by the source of such a brine.

[0011] As a rule, the efficiency of lithium extraction from natural brines depends not only on the specific lithium concentration in the brine, but also on the concentrations of the accompanying ions and impurities, the qualitative and quantitative composition of which can vary greatly depending on the type and location of the natural brine source. Moreover, some special combinations of impurities can greatly affect not only the efficiency of lithium extraction, but also the service life of the sorbent in cycles (working life).

[0012] The presence of interfering ions and impurities can not only significantly increase the cost of lithium extraction, since it is necessary to carry out additional operations to remove interfering components, but also negatively affect the performance characteristics of the sorbents used in such processes. In particular, this leads not only to a drop in lithium extraction productivity, but also to a reduction in the service life of the sorbent, since the above impurities, along with the hydrodynamic effect on the sorbent, accelerate its destruction, leading to disintegration of particles. At the same time, the complexity and inconstancy of the compositions of natural brines, as well as the complexity of the processes occurring in the sorbent at the stages of sorption, washing and desorption, do not allow us to reliably predict changes in the above characteristics of the sorbent in long resource runs.Currently, sorbents based on a chlorine-containing variety of double aluminum and lithium hydroxide (DGAL-C1) are considered the most promising for the sorption extraction of lithium, due to the availability of raw materials for their production and the environmental friendliness of their use.

[0013] It is known from the literature that sorbents based on aluminum hydroxides form layered intercalation compounds in which lithium ions, chloride ions, and water molecules are located between the aluminum hydroxide layers. Various forms of aluminum hydroxide (which can be present in crystalline, polycrystalline, polymorphic, or amorphous forms) can sorb lithium from brines to form intercalated compounds such as 0-1[NX]*2[Al(OH)3] (where X is an anion). Lithium is absorbed by aluminum hydroxide with a two-dimensional layered structure through the intercalation of anions between the layers, while positively charged lithium cations diffuse into the hexagonal cavities formed within the two-dimensional layered structure.

[0014] During operation in sorption-desorption cycles, the capacity of sorbents based on aluminum hydroxides gradually decreases, which is explained by the processes of disorientation and "collapse" of aluminum hydroxide layers due to the fact that the layers temporarily lose the lithium chloride "wedging" them, when lithium passes from the sorbent to the eluate during desorption. An insignificant time of the sorbent's stay in the desorbed state is enough for the distance between some of the layers to decrease (the layers "collapse"), therefore, during subsequent sorption, not all lithium will be able to get into the interlayer space and occupy its vacant places in the interlayer structure of the sorbent, therefore, the sorbent's capacity will inevitably decrease from cycle to cycle.

[0015] Although aluminum hydroxide-based sorbents have been known since the late 1970s, their disadvantage is low stability in cycles (service life), low mechanical strength during lithium extraction from brines and other lithium-containing solutions, and there is currently a need for improved methods and compositions for the selective extraction of lithium from lithium-containing brines, in particular compositions that are easy to synthesize with a high service life and mechanical strength.

[0016] Initially, sorbents were synthesized without a binder.

[0017] For example, from the publication of the US patent application US 2016 / 0317998 A1, published on 03.11.2016, a lithium adsorbent is known based on LiCl-2Al(OH)3 nH2O, where n is in the range from 0.01-10, obtained by granulation without a binder by mixing aqueous solutions of aluminum and lithium salts to obtain a suspension, filtering the suspension to obtain a precipitate, drying the precipitate at a temperature of 20-80 °C for 1-12 hours, then granulating by extrusion to obtain an extrudate, followed by drying the extrudate at a temperature of 20-200 °C for 1-20 hours to obtain a crystalline solid material of the formula LiCl-2Al(OH)3 nH2O.

[0018] The disadvantage of such an adsorbent is the low mechanical strength of its granules and a short service life, due to the crumbling of granules during operation due to the lack of a binder. Particles of aluminum hydroxide, being not bound by a binder, are prone to breaking off from a single volume of sorbent granules and being carried away from the column with the liquid flow, thereby increasing the consumption of the sorbent.

[0019] To eliminate the drawback associated with the low mechanical strength of granules, it is known to use polymer binders for sorbents based on aluminum hydroxides (DGAL-C1) from the class of water-insoluble polymers (PVC).

[0020] A granulated sorbent for extracting lithium from lithium-containing solutions is known from the patent of the Russian Federation RU 2455063, published on 10.07.2012. This sorbent is obtained from a chlorine-containing variety of double aluminum and lithium hydroxide 1LCl2Al(OH)3 nH2O, which in turn is synthesized from a solution of aluminum chloride, pre-mixed with lithium hydroxide or carbonate at an atomic ratio of Al:Li equal to 2.0 - 2.3 with the addition of NaOH to the mixed solution to a pH of 6-7. The resulting precipitate 1С1-2А1(ОН)з nН2О is separated from the solution, dried, ground to a particle size of less than 0.1 mm and granulated with the addition of polyvinyl chloride and methylene chloride as a solvent with the recovery of methylene chloride evaporating during the granulation process and its return to production.

[0021] The main disadvantage of sorbents with a binder based on PVC and its derivatives is low hydrophilicity and, due to this, poor mass exchange processes, since PVC is a non-polar compound and is characterized by poor wettability with water and solutions due to its hydrophobic properties, this hinders the access of lithium to the sorption centers, which reduces the capacity and kinetic parameters of the sorbent. At the same time, this binder does not stabilize the layered structure and these sorbents are also characterized by a low service life in cycles.In addition, the method of its production has disadvantages, in particular, the disadvantage of this method is the need to use filtration equipment to separate the difficult-to-filter DGAL-S1 sediment from the mother liquor, the need to use double drying (DGAL-S1 powder before granulation and granules after granulation), the use of toxic and environmentally hazardous solvent methylene chloride, which worsens sanitary and hygienic conditions in production, the need for an expensive and difficult to operate solvent recovery system.

[0022] In addition to PVC, chlorinated PVC was used as a binder to solve the problem of obtaining granulated sorbents based on aluminum hydroxides. It has greater adhesion to DGAL-S1 particles than PVC and is less expensive.

[0023] For example, the method of obtaining, known from the patent of the Russian Federation RU 2657495, published on 14.06.2018, includes obtaining a powder of a chlorine-containing variety of double aluminum lithium hydroxide (DGAL-C1) from an aluminum chloride solution with an AlCl3 concentration level of 45-220 kg / m3, containing lithium in the form of compounds LiCl, Li2CO3, LiOH H2O or a mixture thereof, at an atomic ratio of Al:Li = 2.0-2.3, with the addition of sodium hydroxide to a pH of the mixed solution of 6 - 7, separating the DGAL-C1 powder from the mother liquor, pulping the DGAL-C1 precipitate, secondary filtration of DGAL-C1, two-stage drying of the DGAL-C1 powder to a residual moisture content of DGAL-C1 of 1.5-2.0% by weight., grinding the powder to a particle size of < 0.10 mm, granulating the powder with the addition of chlorinated polyvinyl chloride and organochlorine solvent by extrusion through dies with a diameter of 5 mm, removing the chlorine-containing solvent with a hot air flow, crushing the extrudate, sieving with the selection of a fraction of at least 1.0 mm and no more than 2.0 mm, drum rolling, giving the granulated sorbent a rounded granule shape. The vapors of the organochlorine solvent and water are separated and condensed from the cooled air flow.

[0024] The main disadvantage of sorbents with a binder based on chlorinated PVC, as well as on PVC, is low hydrophilicity and due to this poor flow of mass exchange processes, since chlorinated PVC is a non-polar compound and is characterized by poor wettability with water and solutions due to its hydrophobic properties, this hinders the access of lithium to the sorption centers, which reduces the capacity and kinetic parameters of the sorbent. At the same time, this binder does not stabilize the layered structure and these sorbents are also characterized by a low service life in cycles. In addition, chlorinated PVC is characterized by a low softening temperature, which does not allow the use of the sorbent for the extraction of lithium from hot brines (for example, geothermal waters), as well as from brines containing organic compounds from a number of petroleum products, since they will "soften" the binder, leading to the loss of mechanical properties in cycles.

[0025] In addition, the disadvantages of the method for obtaining such a sorbent include the need to use filtration equipment to separate the difficult-to-filter DGAL-S1 precipitate from the mother liquor, the need to use double drying and removal of the organochlorine solvent, the use of toxic and environmentally hazardous chlorine-containing solvents (methylene chloride), which worsen sanitary and hygienic conditions in production, and the need for an expensive and difficult-to-use solvent recovery system.

[0026] Therefore, the ideal binder is to use a three-dimensional insoluble polymer with high strength and hydrophilicity, formed in the process of obtaining the sorbent, for example, from polyvinyl alcohol as a binder.

[0027] The closest analogue can be the publication of the international patent application WO2023038546, published on 16.03.2023, which describes a sorbent developed by us earlier for the selective extraction of lithium based on 1DS1-2Al(OH)3 PN2O, where n is in the range from 0.01-10, obtained by a method including obtaining a chlorine-containing variety of double aluminum hydroxide and lithium (DGAL-C1) from an aluminum chloride solution with an AlCl3 concentration level of 45-220 kg / m3. 3, containing lithium, at an atomic ratio of Al:Li = 2.0-2.3: 1 with the addition of sodium hydroxide to adjust the pH of the mixed solution, wherein the pH of the mixed solution is 4-5, the resulting DGAL-C1 is not separated as a precipitate from the reaction mixture and is not dried, but mixed with an aqueous solution of polyvinyl alcohol taken in an amount of 10-15% by weight (in terms of polyvinyl alcohol) from the weight of DGAL-C1, mixed well at a temperature of 60-80 ° C until a homogeneous mass is obtained, dried to a pasty state and extruded, the extrudate is subjected to rolling, giving a rounded (spherical) shape to the granules, the granules are heat treated at 105-120 ° C for 12-24 hours to form an insoluble carbon framework of the sorbent.

[0028] Under the stated conditions, the formation of a three-dimensional carbon-containing framework is ensured during the dehydration of polyvinyl alcohol, and the resulting carbon structures are hydrophilic and wettable, bind the DGAL-C1 particles together, minimizing shedding and increasing mechanical strength. The combination of porosity, low weight and strength of the carbon-containing framework ensures the production of a sorbent with increased capacity.

[0029] The disadvantage of this sorbent is that the specified characteristics are not maintained at a high level over long resource runs.

[0030] Disclosure of invention

[0031] The objective of the present invention and the technical result is to develop a sorbent for extracting lithium with high stability of capacity indicators when operating in sorption-desorption cycles, increasing the service life of the sorbent without losing capacity properties, and maintaining mechanical strength in cycles.

[0032] The technical result achieved by the present invention consists in achieving a set of operational indicators of the sorbent that are maintained at a high level during resource operation, in particular the strength of the sorbent, the dynamic capacity of the sorbent, the average concentration of lithium in the eluate, the efficiency of washing the sorbent from impurities and the purity of the eluate for lithium.

[0033] The strength of the sorbent, which is estimated through the loss of the sorbent from the initial volume and directly the mechanical strength itself. Thus, the loss of the sorbent according to the present invention from the initial volume to the 400th sorption-desorption cycle was no more than 9%, and for some samples of the sorbent according to the present invention no more than 5%, while for known samples from the prior art, including for the prototype sample, the loss of the sorbent can increase to 53%, which inevitably leads to the need to stop the process and reload the sorbent every 100 cycles, while in contrast to a new reloaded portion of the sorbent, the sorbent that has worked 100 cycles before has reduced capacity characteristics, in some cases the decrease in the dynamic volumetric capacity is up to 40%. Also, the improved strength characteristics of the sorbent according to the present invention are confirmed by a study of its mechanical strength.According to this parameter, the sorbent according to the present invention loses no more than 12% by the 400th sorption-desorption cycle, and in some cases no more than 5%, while the loss of mechanical strength for sorbents known from the prior art can reach 84% by the 400th cycle.

[0034] The dynamic capacity of the sorbent depends on its strength characteristics, the number and availability of active sorption centers, as well as on the chemical composition of the initial lithium-containing solution (brine) and the modes of the technological process. For the sorbent according to the present invention, the dynamic capacity remains stably high over 400 sorption-desorption cycles: the initial capacity is 2.10-2.21 g / l, and the capacity at the 400th cycle is 1.95-2.08 g / l, which is no more than 11% of the change in capacity by the 400th cycle. While for the prototype sample this value drops by more than 50%, and for some other sorbents known from the prior art, the drop by the 400th cycle is all of 100%.

[0035] The consequence of maintaining high capacity indicators of the sorbent according to the present invention is a stably high average concentration of lithium in the eluate, which is further in the process used to obtain battery-grade lithium carbonate. Namely, in the initial cycles, the average concentration of lithium in the eluate reaches a value of 0.84-0.89 g / l, and by the 400th cycle, the average concentration of lithium in the eluate is 0.78-0.83 g / l (which is a change of no more than 12%). While the use of the sorbent according to the prototype provides an average concentration of lithium in the eluate in the initial cycles of 0.44-0.87 g / l, and by the 400th cycle 0.03-0.048 g / l (a drop of more than 50%), and for some samples of the sorbent from the prior art, the drop is up to 93%.

[0036] Another technical result of using the sorbent according to the present invention is the efficiency of washing the sorbent from impurities and, as a consequence, the purity of the eluate for lithium. For the sorbent according to the present invention, the purity of the eluate for lithium in the initial cycles is 91-96%, and by the 400th cycle 84-90%. This parameter when using sorbents known from the prior art, including the prototype, is 76-94% (initial cycles) and 5-43% (by the 400th cycle). The quality of washing the sorbent from impurities, such as calcium, magnesium, potassium, sulfate ions, sodium, boron, etc., is determined, among other things, by the capacity and strength parameters for the sorbent according to the present invention, which is indicated in more detail in Table No. 1.

[0037] All of the above effects also make it possible to simplify the sorption-desorption process and reduce the number of operations in the preparation of washing and desorption solutions, since a wider range of solutions known for such purposes can be used as such, since the operational characteristics of the sorbent do not depend on their type (both desalinated water and demineralized water, as well as water with a salt background, are suitable).

[0038] In addition, the use of the sorbent according to the present invention makes it possible to reduce the requirements for its operating conditions, minimize the risk of emergency situations associated with the failure of the sorbent, and also minimize the risk of complete replacement of the sorbent when the sorbent is in a desorbed form for a long time.

[0039] While conducting resource tests of various proprietary samples of sorbents based on the chlorine-containing form of double aluminum and lithium hydroxide DGAL-C1 (1 C1-2A1(OH)3 PN2O), the authors of the present invention unexpectedly discovered that some samples exhibit high dynamic exchange capacity over a much longer resource run.

[0040] Without committing to a specific theory, the authors of the present invention assumed that changes in the modes of obtaining these sorbents allow obtaining samples with a better set of operational characteristics, namely, preserving them over long resource runs. Thus, individual samples began to lose in capacity indicators after 200 sorption-desorption cycles, and some were more effective in these parameters and withstood 2 times more sorption-desorption cycles.

[0041] We conducted EPR (electron paramagnetic resonance) studies of sorbent samples and unexpectedly discovered that the samples that had an increased service life of the sorbent without loss of capacitive properties had paramagnetic properties, in particular, resonant absorption of microwave radiation was observed in the region of magnetic field strength of 3500-3520 mT, while the remaining DGAL-C1 sorbents, as well as the binder, do not have paramagnetic properties.

[0042] It is known from the literature that during operation in sorption-desorption cycles, the capacity of sorbents based on DGAL-C1 gradually decreases, which is explained by the processes of disorientation and "collapse" of aluminum hydroxide layers due to the fact that the layers temporarily lose the lithium chloride "wedging" them, when lithium passes from the sorbent to the eluate during desorption. A short time of the sorbent's stay in the desorbed state is enough for the distance between some of the layers to decrease (the layers "collapse"), therefore, during subsequent sorption, not all lithium will be able to get into the interlayer space and occupy its vacant places in the interlayer structure of DGAL-C1, therefore, the capacity of the sorbent will inevitably decrease from cycle to cycle.

[0043] Without limiting ourselves to a specific theory, we can assume the following. Macromolecules of the hydroxyl-containing polymer introduced into DGAL-C1 as a binder, under the selected heat treatment mode with catalytic dehydration, form a system of carbon structures with localized and delocalized electrons, "wedge" the DGAL-C1 layers and stabilizing them, preventing the aluminum hydroxide layers from approaching each other and "collapsing" when lithium is released during desorption with the formation of zones of aluminum y-hydroxide that are inactive in terms of lithium absorption. The response intensity in the EPR spectrum reflects the spin density of paramagnetic centers formed by unpaired electrons of carbon structures formed during catalytic dehydration and oxidation of the hydroxyl-containing polymer molecules inside the DGAL-C1 layers.

[0044] Without committing ourselves to a specific theory, we can also use this effect to explain the stability of the sorbent's lithium capacity in cycles during washing and desorption with demineralized (desalinated) water, which was unexpectedly obtained, since for DGAL-C1 sorbents, a positive effect of the salt background on the stability of the sorbent during washing was previously revealed, as well as an increase in the stability of the sorbent in cycles during desorption with weak solutions of lithium chloride, which do not allow the sorbent to be "re-desorbed" during desorption, thereby preventing irreversible loss of its properties.

[0045] Thus, the proposed sorbent with paramagnetic properties gives us a high degree of freedom of choice when working with different liquids and a wide range of operating modes, including the possibility of deeper desorption due to washing with desalinated water during long resource runs, without causing loss of sorbent properties. In general, we have a sorbent that is less demanding to operating conditions, we minimize the risk of emergency situations associated with sorbent failure during a long shutdown of the sorption column with the sorbent in desorbed form, and the personnel servicing the sorption unit have more time to make a decision before mothballing the column with the desorbed sorbent. And

[0046] Everything mentioned above fundamentally distinguishes the sorbent we obtained and the method of its production from the sorbent and the method of its production known from the prototype.

[0047] Thus, in order to solve the above-mentioned problem and achieve a technical result, a sorbent is proposed for extracting lithium from lithium-containing solutions based on a chlorine-containing form of double aluminum and lithium hydroxide, characterized by the fact that the said sorbent has a paramagnetic property.

[0048] Thus, imparting even insignificantly intense paragmanite properties to the sorbent allows to increase the service life of the sorbent to some extent.

[0049] In a preferred embodiment, the said sorbent has a resonant absorption of microwave radiation in the region of magnetic field strength of 3500-3520 mT.

[0050] In a more preferred embodiment, the intensity of the resonant absorption of microwave radiation of the sorbent in the region of magnetic field strength of 3500-3520 mT is from 0.1 *10 7 up to 10*10 7 , preferably from 0.5*10 7 up to 7*10 7 , more preferably from 0.7*10 7 up to 4.5*10 7, more preferably from 0.8*10 7 up to 4.4*10 7 .

[0051] Paramagnetic property (paramagnetism, paramagnetism) is the property of bodies placed in an external magnetic field to become magnetized (acquire a magnetic moment) in a direction that coincides with the direction of this field.

[0052] The paramagnetic property of the sorbent was assessed by the response on the EPR (electron paramagnetic resonance) spectrum. The EPR spectrum is the dependence of the intensity of absorption of electromagnetic radiation by the sample on the strength of the external magnetic field.

[0053] In a preferred embodiment, the chlorine-containing form of aluminum lithium double hydroxide corresponds to the formula ЫCl-2А1(ОН)3nH2O, where n is from 0.01 to 10.

[0054] In a preferred embodiment, the sorbent contains a chlorine-containing form of double aluminum lithium hydroxide and a binder.

[0055] In a preferred embodiment, the binder is an aqueous solution of polyvinyl alcohol, or an aqueous solution of water-soluble cellulose derivatives.

[0056] In a preferred embodiment, the amount of binder is 10-20% by weight, more preferably 10-15% by weight, based on the dry substance of the binder from the weight of the said chlorine-containing form of double aluminum and lithium hydroxide. In a more preferred embodiment, the polyvinyl alcohol solution is an aqueous solution of polyvinyl alcohol with a concentration of 3-10% by weight.

[0057] In a more preferred embodiment, the aqueous solution of water-soluble cellulose derivatives comprises carboxymethylcellulose.

[0058] Also, to solve the above-mentioned problem and achieve the technical result, it is proposed to use the above-mentioned sorbent as a sorbent for extracting lithium from lithium-containing solutions.

[0059] Also, in order to solve the above-mentioned problem and achieve the technical result, a method for obtaining the above-mentioned sorbent is proposed, which includes the following stages: a) obtaining a chlorine-containing form of double aluminum and lithium hydroxide; b) mixing the chlorine-containing form of double aluminum and lithium hydroxide with a binder, which is an aqueous solution of polyvinyl alcohol, or an aqueous solution of water-soluble cellulose derivatives, wherein the amount of binder is 10-20% by weight, calculated on the dry substance of the binder from the weight of the said chlorine-containing form of double aluminum and lithium hydroxide; c) drying the product obtained in stage b); d) granulating the product obtained in stage c).e) heat treatment of the granules, characterized in that the heat treatment of the granules in step e) includes the following stages: el) increasing the temperature of the environment surrounding the granules from 75-85°C to 95-105°C for 1-3 hours, e2) holding for 0.3-2 hours at a temperature of the environment surrounding the granules of 95-105°C, e3) increasing the temperature of the environment surrounding the granules from 95-105°C to 110-130°C for 1-3 hours, e4) holding for 12-24 hours at a temperature of the environment surrounding the granules of 110-130°C.

[0060] The basis of the specified method contains the process stages described for the sorbent developed by us earlier in the publication of the international application WO2023038546, published on 16.03.2023. However, unlike the method for producing the sorbent described in this source, the method of the present invention is distinguished by the fact that at certain stages of the process, namely at the stages associated with the temperature effect on the reaction mass, a certain temperature regime must be observed. In particular, the authors of the present invention, when searching for solutions to optimize the process of obtaining the sorbent in order to increase the overall efficiency of the sorbent production technology, namely, in order to reduce the time for certain process operations, found that changing the heating mode, primarily at the stage of heat treatment of the sorbent granules, makes it possible to obtain the sorbent of the present invention, namely, a sorbent characterized by paramagnetic properties.At the same time, the authors of the present invention suggest that it is not so much the time of heat treatment that influences the achievement of this parameter, but the temperature regime.

[0061] The method for producing a chlorine-containing form of double aluminum lithium hydroxide is disclosed in the above-mentioned publication of international application WO2023038546 and includes producing a chlorine-containing form of double aluminum lithium hydroxide (DG AL-C1) from an aluminum chloride solution with an AlCl3 concentration level of 45-220 kg / m3. 3 , containing lithium at an atomic ratio of Al:Li = 2.0-2.3:1, with the addition of sodium hydroxide to regulate the pH of the mixed solution within 4-5. The resulting DGAL-C1 is not separated as a precipitate from the reaction mixture and is not dried, but is mixed with the binder at stage b).

[0062] In a preferred embodiment, mixing in step b) is carried out at a temperature of 50-80°C for 1-6 hours, more preferably at a temperature of 50-70°C for 1-3 hours.

[0063] In a preferred embodiment, the mixing in step b) is preferably started at room temperature until a homogeneous mass is obtained, and then the temperature is increased to 50-80°C, more preferably to 50-70°, for 0.5-3 hours, preferably 1-2 hours.

[0064] In a preferred embodiment, in step c) the drying of the product obtained in step b) is carried out at a temperature of 80-90°C for 7-24 hours, more preferably for 20 hours.

[0065] In a preferred embodiment, in step c) the drying of the product is carried out with stirring, while gradually reducing the stirring speed. In a preferred embodiment, the heat treatment of the granules in step e) includes the following steps: el) increasing the temperature of the environment surrounding the granules from 80°C to 95-100°C for 1-3 hours, e2) holding for 1-2 hours at a temperature of the environment surrounding the granules of 95-100°C, e3) increasing the temperature of the environment surrounding the granules from 95-100°C to 120-130°C for 1-3 hours, e4) holding for 12-24 hours at a temperature of the environment surrounding the granules of 120-130°C.

[0066] The preferred and more preferred mode allow obtaining a sorbent with the best paramagnetic properties, which provide the best set of its operational characteristics during resource runs.

[0067] Without being bound by any theory, the authors of the present invention believe that paramagnetic properties appear in the sorbent precisely due to certain temperature effects, for example, as described in the method of the present invention.

[0068] The authors believe that the achievement of paramagnetic properties in the sorbent can be achieved not only by regulating the temperature regime at the stage of heat treatment of the granules, but also at the stages of temperature mixing of DGAL-S1 with the binder and / or at the stage of drying the reaction mass to a pasty state.

[0069] Investigating this effect of the influence of temperature conditions of the method of obtaining the sorbent on the appearance of paramagnetic properties, especially in light of the publication "PARAMAGNETIC RESPONSE OF CARBON NANOTUBES: TEMPERATURE DEPENDENCIES" (authors A. N. Ulyanov, E. V. Suslova, K. I. Maslakov, A. V. Fionov, N. N. Kuznetsova, R. K. Singh, S. V. Savilov, "Journal of Physical Chemistry", 2022, Vol. 96, No. 6, pp. 822-827, DOI: 10.31857 / S0044453722060292), the authors suggested that the specified temperature effect leads to delocalization of electrons of the outer electron shells of carbon structures in the corresponding layers of the sorbent, where the main processes of sorption and desorption of lithium occur. And most likely, the indicated delocalization of electrons is sufficient to form paramagnetic properties in these layers, which stabilize these layers from “collapse” and destruction during operation, including long-term operation, up to 400 sorption-desorption cycles.According to the above source of information, a more correct explanation for the appearance of the paramagnetic property can be given by the following quote: the paramagnetic response “is due to the spin interaction between delocalized (mobile) electrons and localized π-electrons enclosed in the extended aromatic structure.”

[0070] Again, without committing ourselves to any theory, the authors can only assume the mechanism of the influence of the paramagnetic property on the technical result achieved when using the sorbent according to the present invention in the processes of lithium extraction from hydromineral raw materials. It is possible that either the paramagnetic property creates a certain "damping / wedging" effect in the layers and does not allow them to "collapse", or another possible explanation for the unexpected effect is the uniqueness of the carbon structures of this layer, which are possibly stronger at the "micro level", but at the same time they have a paramagnetic property. But, most likely, as was said above and as follows from the experiments in Table 1, it is the paramagnetic property that unexpectedly strengthens the sorbent and has a positive effect on the operational properties of the sorbent described above in the technical result, including, and most importantly, during the resource runs of the sorbent according to the present invention.In this case, as follows from the present invention, the sorbent exhibits the best technical result at certain paramagnetic property values. At the same time, even at a small paramagnetic property value, the sorbent exhibits an efficiency that is somewhat higher than that of other sorbents known from the prior art, and sorbents having a resonant absorption intensity of sorbent microwave radiation within the range of 0.5*10. 7 up to 7*10 7 in the region of magnetic field strength of 3500-3520 mT show even better results. The authors of the present invention believe that the paramagnetic property and / or carbon structures exhibiting such a property provide better accessibility of the sorbent layers for mass-exchange sorption-desorption processes.

[0071] In a preferred embodiment, in step d), the granulating comprises rolling the product to give it a substantially spherical (substantially round) shape.

[0072] In a preferred embodiment, in step b) an aqueous solution of polyvinyl alcohol with a concentration of 3-10% by weight, more preferably 3-5% by weight is used. In a preferred embodiment, the aqueous solution of water-soluble cellulose derivatives contains carboxymethyl cellulose.

[0073] Without limiting ourselves to a particular theory, we can assume the following.

[0074] Macromolecules of polyvinyl alcohol are distributed between particles of the obtained chlorine-containing form of double aluminum lithium hydroxide (hereinafter also referred to as DGAL-C1) at the stage of mixing reagents at 50-80°C, and during subsequent heat treatment of the rounded granules obtained from the mixture with pH=4-5, in the presence of aluminum ions as a catalyst, the molecules of polyvinyl alcohol undergo dehydration with the formation of a system of cross-links between the macromolecules, as well as a system of alternating double bonds within the macromolecules C=C, while water molecules are released into the gas phase during heat treatment at 100-120°C, the mass loses solubility in water and other solvents due to a three-dimensional (cross-linked) carbon-containing framework, which ultimately represents a system of interpenetrating pores and channels.

[0075] The sorbent obtained in accordance with the claimed method has a free internal volume and has increased hydrophilicity due to better wettability and availability of DGAL-S1, has a higher capacity and is less prone to crumbling and crushing during operation, since the bonds of DGAL-S1 with the framework are stronger. The method is environmentally friendly, does not require the use of toxic organochlorine solvents.

[0076] Everything mentioned above fundamentally distinguishes the sorbent we obtained and the method of its production from the sorbents and methods of production known from the state of the art.

[0077] The preferred parameters of the method are related to the following.

[0078] The most optimal pH of the mixed solution is 4-5. When the pH decreases below 4, the yield of DGAL-CI decreases and soluble aluminum and lithium salts are formed; when the pH is above 5, the catalytic effect of pH on dehydration and the formation of a porous carbon-containing framework decreases.

[0079] The amount of polyvinyl alcohol or water-soluble cellulose derivatives from the mass of DGAL-CI less than 10% by weight reduces the strength of the sorbent matrix formed during heat treatment and does not lead to a decrease in the mechanical strength of the product, since polyvinyl alcohol and water-soluble cellulose derivatives are raw materials for creating a carbon-containing framework. On the other hand, an increase in their amount from the mass of DGAL-C1 more than 20% by weight leads to a decrease in capacity, since the content of DG AL-C1 in the sorbent matrix decreases.

[0080] A mixing temperature of the chlorine-containing form of double aluminum and lithium hydroxide with a binder of less than 60°C leads to a prolongation of the process and worsens the degree of mixing due to an increase in the viscosity of the mixture. A mixing temperature of more than 80°C is undesirable, since the incipient processes of cross-linking and structuring of the binder macromolecules under mechanical shear during mixing can lead to the production of a friable gel-like product of low adhesion, which after extrusion and rolling will have reduced mechanical strength.

[0081] The use of a binder with a concentration of less than 3% by weight leads to excessive watering of the mixture and requires additional costs for drying. The use of a binder solution with a concentration of more than 10% by weight leads to deterioration in mixing of the binder solution with the DGAL suspension due to the higher viscosity of the binder solution and the formation of a non-uniform product.

[0082] Brief description of the drawings

[0083] The drawings are presented for a better understanding of the invention, however, it will be obvious to a person skilled in the art that the disclosed invention is not limited to the embodiments shown therein.

[0084] Fig. 1 shows the initial experimental spectrum of electron paramagnetic resonance (derivative of the absorption spectrum) of the sorbent according to the prototype.

[0085] Fig. 2 shows the electron paramagnetic resonance spectrum of the sorbent according to the prototype.

[0086] Fig. 3 shows the initial experimental electron paramagnetic resonance spectrum (derivative of the absorption spectrum) of the sorbent in accordance with the present invention.

[0087] Fig. 4 shows the electron paramagnetic resonance spectrum of the sorbent in accordance with the present invention.

[0088] Embodiments of the invention

[0089] The best embodiment of the invention Below are examples that do not limit but illustrate the possibility of implementing the invention.

[0090] An example of obtaining a sorbent with a binder based on chlorinated polyvinyl chloride (C-PVC).

[0091] A 10-L four-neck flask equipped with a thermocouple, a dropping funnel, a glass combination electrode of a pH meter, and a mechanical stirrer was placed in a bath to maintain the temperature. 2 L of a lithium chloride solution with a lithium concentration of 5.8 g / L and 812 g of hexahydrate aluminum chloride (atomic ratio Al:Li = 2.0:1) were loaded and stirred until the aluminum chloride was completely dissolved. While stirring, a sodium hydroxide solution (6 M) in an amount of 1.69 L was added dropwise, and the mixture in the flask turned white due to the formation of DGAL-C1, the resulting pH of the mixture was 5. The DGAL-C1 precipitate was separated from the mother liquor on a Nutsche filter and pulped in 5 L of distilled water to wash off residual NaCl. After washing and separating the sediment on a Nutsche filter, the sediment was spread on baking sheets in a layer thickness of no more than 10 mm and dried at 105 °C to a residual moisture content of 1.5-2.0% by weight.The dried semi-finished product was ground in a ball mill to a particle size of no more than 0.1 mm. The powder was mixed with a solution of C-PVC in methylene chloride. The amount of binder (C-PVC) by weight of DGAL-C1 was 10% by weight (in terms of C-PVC). The binder (C-PVC) was mixed with DGAL-C1 powder in a mixer at 20 °C for 6 hours. During the specified time, C-PVC was completely distributed between the DGAL-C1 particles. The resulting mixture was dried at 45 °C to partially remove methylene chloride and increase the viscosity of the mixture. The mass was extruded in a single-screw extruder with a cutting knife through dies with a diameter of 3 mm. The extrudate was transferred to a drum granulator for pelletizing to obtain rounded particles with a diameter of ~3 mm. The dried product was round granules with a particle diameter of ~3 mm and a weight of 1055 g.

[0092] An example of obtaining a sorbent using a prototype

[0093] In a 10-liter four-neck flask equipped with a thermocouple, a dropping funnel, a glass combination electrode of a pH meter, and a mechanical stirrer, placed in a bath to maintain the temperature, 2 liters of a lithium chloride solution with a lithium concentration of 5.8 g / l and 812 g of 6-aqueous aluminum chloride (atomic ratio Al:Li = 2.0: 1) were loaded, stirred until the aluminum chloride was completely dissolved. Sodium hydroxide solution (6 M) was added dropwise with stirring in an amount of 1.68 l, and the mixture in the flask turned white due to the formation of DGAL-Cl, the resulting pH of the mixture was 4. After finishing dosing the sodium hydroxide solution, 1112 g of 3% polyvinyl alcohol (PVA) solution (10% in terms of PVA from the mass of ЫС12А1(ОН)з) were loaded into the flask with stirring. After finishing dosing, heating was turned on to 60 °C, after reaching the set temperature, stirring was carried out until a homogeneous mass was obtained (1 hour).The mass was then transferred from the flask to a baking tray and dried in a thermostat at 80 °C to a paste-like state for 15 hours. The mass was extruded in a single-screw extruder with a cutting knife through dies with a diameter of 3 mm. The extrudate was transferred to a drum granulator for rolling to obtain round particles with a diameter of 3 mm. The yield of granulate was 1800 g. The resulting granules were heat-treated at 105 °C for 24 hours. The dried product was round granules of black color with a particle diameter of 2 mm and a weight of 1245 g.

[0094] An example of obtaining sorbents according to the invention

[0095] A 10-L four-neck flask equipped with a thermocouple, a dropping funnel, a glass combination electrode of a pH meter, and a mechanical stirrer, placed in a bath to maintain the temperature, was charged with 2 L of a lithium chloride solution with a lithium concentration of 5.8 g / L and 812 g of hexahydrate aluminum chloride (atomic ratio Al:Li = 2.0 : 1) or 934 g of hexahydrate aluminum chloride (atomic ratio Al:Li = 2.3 : 1, according to Table 1), stirred until the aluminum chloride was completely dissolved. While stirring, a sodium hydroxide solution (6 M) in an amount of 1.68-1.69 L was added dropwise to pH = 4-5, while the mixture in the flask turned white due to the formation of DGAL-Cl. After finishing dosing the sodium hydroxide solution, 3-10% by weight of an aqueous solution of the binder was loaded into the flask with stirring in the amount indicated in Table 1, based on the mass of ЫС1-2А1(ОН)з.After finishing dosing, heating was turned on to 50-70 °C and maintained for a specified time, according to the mixing mode according to Table 1. Then the mass was dried according to the selected drying mode (Table 1). The mass was extruded in a single-screw extruder with a cutting knife through dies with a diameter of 3 mm. The extrudate was transferred to a drum granulator for rolling to obtain rounded particles with a diameter of 3 mm. The resulting granules were heat treated according to the selected heat treatment mode (Table 1). The final product was rounded granules with a particle diameter of 2-3 mm.

[0096] The study of the properties of the obtained sorbents and their characteristics are presented below.

[0097] Tests of the sorbents obtained according to the above examples were carried out under dynamic conditions of lithium sorption, according to the conditions given in Table 2.

[0098] Before testing, the sorbent on the Buchner funnel was washed with water to remove sodium chloride to a concentration lower than in the initial solution used for sorption and to free the container of lithium. Water consumption for washing was 10 volumes.

[0099] The test results are shown in Table 1 and Table 2.

[0100] Thus, our studies have shown that the sorbent obtained in accordance with the claimed method provides increased capacity when extracting lithium from solutions and has high mechanical strength. The method is characterized by its technological effectiveness and ensures the production of a sorbent in the form of mechanically strong granules.

[0101] The proposed sorbent has a 2-2.5 times greater service life, namely up to 300-400 sorption-desorption cycles without loss of capacity properties and while maintaining mechanical strength in cycles.

[0102] The described examples of the invention are given solely for illustrative purposes. It will be obvious to a specialist that other embodiments of the invention are possible without changing the essence of the invention. Table 1

[0103]

[0104] "The paramagnetic properties were assessed based on the response in the EPR spectrum; the studies were carried out at frequencies of 9.8-9.9 GHz on a BRUKER EMX 6 / 1 spectrometer.

[0105] Table 2

[0106]

[0107] In the above tables:

[0108] Solution No. 1 - underground formation water (in g / l): lithium Li + - 0.435; sodium Na + - 114.5; potassium K + - 9.4; chlorine SG - 196.0; magnesium Mg 2+ - 3.6; calcium Ca 2+ - 1.7; sulfates (SO4 2 ') - 6.5;

[0109] Solution No. 2 - salar brine (in g / l): lithium Li +- 0.35; sodium Na + - 105.2; potassium K + - 12.0; chlorine SG - 285.1; magnesium Mg 2+ - 40.0; calcium Ca 2+ - 0.8; sulfates (SO4 2 ') - 10.1; boron - 0.5.

[0110] Solution "P" - solution for washing (g / l): lithium Li + - 0.043; sodium Na + - 11 ,4; potassium K + - 0.9; chlorine SG - 19.6; magnesium Mg 2+ - 0.36; calcium Ca 2+ - 0.17; sulfates (SO4 2 ') - 0.65.

[0111] "DV" - Demineralized water

[0112] PVA - 3 - 10% by weight, solution of polyvinyl alcohol in water

[0113] PVA - 50% wt, polyvinyl acetate dispersion in water

[0114] The dynamic exchange capacity for Li was determined using the formula from GOST 20255.1-84 (GOST 20255.2-84).

[0115] Dynamic exchange capacity for lithium DOE, g / l, is calculated using the formula:

[0116] DOE = (U1 * C(Li)„ Cx) / Vc where V 1 is the total volume of the working solution passed through the column with the sorbent until lithium ions appear in the samples, dm 3 ,

[0117] C(Li)ncx - lithium concentration in the initial working solution, g / dm 3 ,

[0118] Vc - volume of sorbent in the column, dm 3 .

[0119] Mechanical strength was determined according to GOST 95.291-86, in particular in the following way: in a graduated cylinder with a capacity of 100 cm 3 load the sodium chloride solution and add the wet sorbent in portions (fraction 2.0-3.0 mm). Compact by tapping the bottom of the cylinder on a wooden surface until shrinkage stops, then bring the volume of the sorbent in the cylinder to 100 cm 3 After compaction, the volume occupied by the sorbent in the cylinder is measured with an error of no more than 1 cm. 3 .

[0120] The sorbent is transferred from the cylinder with the sodium chloride solution to the mill. The total volume of the sorbent and the sodium chloride solution should be about 200 cm3 The balls are loaded into the mill, it is hermetically sealed, secured on a roller machine and the motor is turned on.

[0121] The sorbent is ground for 30 minutes. Then the balls are separated from the sorbent on a sieve with a cell size of 5 mm. The ion exchanger grains are collected together in a cylinder and the volume fraction of the working fraction (2.0-3.0 mm) is determined. Then the mechanical strength of the sorbent bn, in percent, was calculated using the formula bn = (vi * 100) / v where vi is the volume of the sorbent of the 2.0-3.0 mm fraction after testing for mechanical strength, %; v is the volume of the sorbent taken for testing, cm 3 .

[0122] The measurement result is taken as the arithmetic mean of the results of at least two parallel measurements, the permissible differences between which should not exceed 2%. The value of the analysis result is rounded to whole percent.

[0123] The loss of sorbent from the initial volume (in %) was determined by comparing the height of the sorbent layer in the column before the start of the tests to the height of the sorbent layer in the column for a certain cycle using the following formula:

[0124] (No-Np) / N о *100%

[0125] The average concentration of lithium in the eluate was calculated using the formula:

[0126] Ministry of Internal Affairs - V f where Ci(Li) is the concentration of lithium in the i-th volume of eluate, g / l;

[0127] Vi is the i-th volume of eluate.

[0128] The purity of the eluate for lithium was determined using the formula: where Ce(Li) is the concentration of lithium in the eluate, g / l;

[0129] WITH е (M) - concentration of ions in the eluate (lithium, calcium, magnesium, sodium, potassium, boron, sulfates), g / l

[0130] Paramagnetic properties were assessed based on the response in the EPR spectrum; studies were carried out at frequencies of 9.8–9.9 GHz using a BRUKER EMX 6 / 1 spectrometer.

Claims

27 Invention formula 1. A sorbent for extracting lithium from lithium-containing solutions based on a chlorine-containing form of double aluminum and lithium hydroxide, characterized in that the said sorbent has a paramagnetic property.

2. The sorbent according to paragraph 1, characterized in that the sorbent has a resonant absorption of microwave radiation in the region of magnetic field strength of 3500-3520 mT.

3. The sorbent according to paragraph 2, characterized in that the intensity of the resonant absorption of microwave radiation of the sorbent in the region of magnetic field strength of 3500-3520 mT is from 0.1*10 7 up to 10*10 7 , preferably from 0.5*10 7 up to 7*10 7 , more preferably from 0.7*10 7 up to 4.5*10 7 , more preferably from 0.8* 10 7 up to 4.4*10 7 .

4. The sorbent according to claim 1, characterized in that the chlorine-containing form of double aluminum and lithium hydroxide corresponds to the formula ЫС1-2А1(ОН)з nН2О, where n is from 0.01 to 10.

5. The sorbent according to claim 1, characterized in that the sorbent contains a chlorine-containing form of double aluminum and lithium hydroxide and a binder.

6. The sorbent according to paragraph 5, characterized in that the binder is an aqueous solution of polyvinyl alcohol, or an aqueous solution of water-soluble cellulose derivatives.

7. The sorbent according to claim 6, characterized in that the amount of binder is 10-20% by weight, more preferably 10-15% by weight, calculated on the dry substance of the binder from the weight of the said chlorine-containing form of double aluminum and lithium hydroxide.

8. The sorbent according to claim 6, characterized in that the aqueous solution of polyvinyl alcohol is an aqueous solution of polyvinyl alcohol with a concentration of 3-10% by weight.

9. The sorbent according to claim 6, characterized in that the aqueous solution of water-soluble cellulose derivatives contains carboxymethyl cellulose.

10. Use of the sorbent according to paragraph 1 as a sorbent for extracting lithium from lithium-containing solutions.

11. A method for producing a sorbent according to claim 1, comprising the following steps: a) obtaining a chlorine-containing form of double aluminum and lithium hydroxide; b) mixing the chlorine-containing form of double aluminum and lithium hydroxide with a binder that is an aqueous solution of polyvinyl alcohol, or an aqueous a solution of water-soluble cellulose derivatives, wherein the amount of binder is 10-20% by weight, based on the dry substance of the binder from the weight of the said chlorine-containing form of double aluminum and lithium hydroxide; c) drying the product obtained in step b); d) granulating the product obtained in step c); e) heat treatment of the granules; characterized in that the heat treatment of the granules at stage e) includes the following steps: el) increasing the temperature of the environment surrounding the granules from 75-85°C to 95-105°C for 1-3 hours, e2) holding for 0.3-2 hours at a temperature of the environment surrounding the granules of 95-105°C, e3) increasing the temperature of the environment surrounding the granules from 95-105°C to 110-130°C for 1-3 hours, e4) holding for 12-24 hours at a temperature of the environment surrounding the granules of 110-130°C.

12. The method according to paragraph I, characterized in that mixing in stage b) is carried out at a temperature of 50-80°C for 1-6 hours, preferably at a temperature of 50-70°C for 1-3 hours.

13. The method according to claim 12, characterized in that mixing in step b) is preferably started at room temperature until a homogeneous mass is obtained, and then the temperature is increased to 50-80°C, preferably to 50-70°C for 0.5-3 hours, preferably 1-2 hours.

14. The method according to claim 11, characterized in that in step c) the drying of the product obtained in step b) is carried out at a temperature of 80-90°C for 7-24 hours, preferably for 20 hours.

15. The method according to claim 14, characterized in that in stage c) the drying of the product is carried out with stirring, while gradually reducing the stirring speed.

16. The method according to paragraph 11, characterized in that the heat treatment of the granules in stage e) includes the following steps: el) increasing the temperature of the environment surrounding the granules from 80°C to 95-100°C for 1-3 hours, e2) holding for 1-2 hours at a temperature of the environment surrounding the granules of 95-100°C, e3) increasing the temperature of the environment surrounding the granules from 95-100°C to 120-130°C for 1-3 hours, e4) holding for 12-24 hours at a temperature of the environment surrounding the granules of 120-130°C.

17. The method according to claim 11, characterized in that in step d) granulation includes rolling the product obtained in step c) until it is given a substantially spherical (substantially round) shape.

18. The method according to claim 11, characterized in that in step b) an aqueous solution of polyvinyl alcohol with a concentration of 3-10% by weight, more preferably 3-5% by weight, is used.

19. The method according to paragraph I, characterized in that the aqueous solution of water-soluble cellulose derivatives contains carboxymethyl cellulose.

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