RU2805741C1 - Granule for sorption of lithium from aqueous solution - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: lithium extraction from lithium-containing chloride brines, from natural brines, process solutions and wastewater from oil and gas production, chemical, chemical-metallurgical and biochemical industries. A granule for sorption of lithium from an aqueous solution contains sorbent particles from a chlorine-containing variety of double hydroxide of aluminum and lithium (DHAL-Cl) and a waterproof spherical core coated with a solution-permeable composite of sorbent particles and a hydrophilic binder. The hydrophilic binder has an open-pore structure.

EFFECT: increasing the efficiency of the process of sorption of lithium from oil, fat, and oil-contaminated aqueous solutions and desorption of lithium from granules.

10 cl, 6 dwg, 11 ex

Description

The proposed solution relates to the field of lithium extraction from lithium-containing chloride brines, from natural brines, process solutions and wastewater from oil and gas production, chemical, chemical-metallurgical and biochemical industries.

The closest to the proposed solution is a sorbent granule for extracting lithium from lithium-containing brines in the production of commercial lithium products (RF patent No. 2657495, IPC B02J 20/30, 2018), which is formed from particles of a chlorine-containing variety of double hydroxide of aluminum and lithium (DHAL -Cl). The disadvantage of the known solution is the low efficiency of the process of sorption of lithium from oil-, fat-, oil-contaminated aqueous solution and desorption of lithium from granules, since:

• The central part of the granule (core) of the sorbent works ineffectively in the case of dynamic (time-limited) sorption.

• Granules are formed entirely from sorbent, which sharply increases the cost of granules from an expensive sorbent (DGAL-Cl) and the internal diffusion resistance to the sorption process, increasing the sorption time and reducing productivity.

• Granules formed entirely from a sorbent with a porous structure throughout the entire volume have a high retention capacity for parasitic salts from the initial target solution, which require a long process of leaching during desorption.

• When using an upward sorption/desorption flow, a low rate of brine and washing liquid is set through the granular sorbent bed to prevent the entrainment of sorbent granules, which especially negatively affects the efficiency of the process due to the high cost of the sorbent.

• The sorbent granules become contaminated with oil, fat, and petroleum products contained in the brine, which reduces the capacity of the sorbent.

The technical result of the proposed solution is to increase the efficiency of the process of lithium sorption from oil, fat, and oil-contaminated aqueous solutions and lithium desorption from granules due to:

• The surface layer of the sorbent granule works with greater efficiency, since its capacity is used completely within a limited sorption / desorption time.

• Replacement of the sorbent of the internal part of the granule with a core, which reduces the cost of granules and internal diffusion resistance to the sorption process, reducing sorption time and increasing productivity.

• Increasing the efficiency of washing the sorbent by reducing the amount and easier and faster washing out of parasitic salts.

• Increasing (expanding the range) the rate of filtration of solution and washing liquid through a layer of granular sorbent, since by changing the core material, its density and other parameters, the entrainment of sorbent granules by the flow of solution and washing liquid can be significantly reduced.

• Preventing contamination of sorbent granules with oil, grease, and oil contaminants through the use of a hydrophilic binder, which ensures the creation and retention of a protective water shell around the granule, preventing the interaction of oil, grease, and oil contaminants contained in the filtered solution with the granule.

This technical result is achieved by the fact that in a granule for sorption of lithium from an aqueous solution containing sorbent particles from a chlorine-containing variety of double hydroxide of aluminum and lithium, the granule contains a waterproof spherical core coated with a solution-permeable composite of sorbent particles and a hydrophilic binder. The hydrophilic binder has an open-pore structure. The hydrophilic binder is limitedly soluble in water at the granulation stage. The maximum binder content in terms of dry residue is no more than 40% by weight of sorbent particles. The average granule size is not less than 0.3 mm and not more than 3.0 mm, preferably not less than 0.5 mm and not more than 1.0 mm. The average particle size of the sorbent does not exceed 50 microns, preferably 10 microns. The average thickness of the sorption coating of the core does not exceed 150 microns, preferably 100 microns. The granule can be coated with a protective layer of tripoli with an average particle size of no more than 10 microns. The core can be made of glass or a binder. The granule core can be made hollow. The amount of adhesion between the core and the binder must be no less than the amount of cohesion of the binder.

Making granules with a waterproof spherical core increases the efficiency of the process of lithium sorption from oil, fat, and oil-contaminated aqueous solutions and desorption of lithium from granules due to:

• reducing the amount of expensive sorbent (DGAL-Cl) per granule, and, accordingly, reducing the cost of the granule;

• reducing the time of lithium sorption-desorption, since reducing the thickness of the sorbent layer reduces the internal diffusion resistance to the sorption-desorption process;

• expands the range of filtration speed of solution and washing liquid through a layer of granules, as it allows you to change the core material, its density and other parameters.

Making the core waterproof reduces desorption time by preventing solution from entering the interior of the granule.

Making the core spherical allows you to obtain granules of a more regular spherical shape and more accurately maintain their sizes, which improves the filtration process through a layer of granules, as it ensures a more uniform porosity of the layer, reduces the likelihood of compaction of the layer, the formation of stagnant zones and punching of channels.

Sorbent particles together with a hydrophilic binder create a sorbent composite shell (sorption coating) around the granule, which is permeable to the solution and protects the granule from oil, grease, and petroleum contaminants contained in the filtered solution. The hydrophilicity and porosity of the sorbing shell makes it possible to create a protective water shell around the granule.

The open-pore structure of the hydrophilic binder significantly increases the wettability of the binder surface with an aqueous medium and the integrity of the protective water shell around the granule due to the capillary effect.

The use of a hydrophilic binder, which is limitedly soluble in water at the granulation stage, makes it possible to increase the porosity of the binder and, accordingly, the sorption coating. If the maximum content of the granule binder in terms of dry residue is no more than 40% of the mass of the granule sorbent particles, then this ensures the creation of open pores between the sorbent particles that are not filled with binder.

To prevent granules from being carried away, the average granule size should be at least 0.3 mm (preferably at least 0.5 mm). To maximize the sorption surface, the average granule size should be no more than 3.0 mm (preferably no more than 1.0 mm), and the average sorbent particle size should not exceed 50 μm (preferably 10 μm). To reduce the internal diffusion resistance to the sorption process, the average thickness of the sorption coating of the core should not exceed 150 microns, preferably 100 microns.

To increase the efficiency of protecting granules from oil, fat, and petroleum contaminants contained in the filtered solution, the granule can be additionally (on top of the sorption coating) coated with a protective layer of tripoli with an average particle size of no more than 10 microns. The open-porous structure of tripoli and the pores formed between its particles ensure the effective creation and retention of a protective water shell around the granule. When using a fraction of tripoli more than 10 microns, the protective oleophobic coating loses its continuity and strength of binding to the sorbent layer. Since tripoli is a soft rock, its large particles are the least durable part of the coating and, as a result, upon contact with an aqueous environment, the tripoli coating is easily destroyed by mechanical stress. This is especially true when the granules remain in water for a long time.

The granule core can be made of various substances, in particular glass or a binder. The core may also be made, for example, of metal, in particular lead (when greater weight is required) or ceramic (when increased strength, manufacturability, chemical neutrality or low cost are required). Depending on the characteristics of the sorption process, the core can be solid (when greater weight and/or strength is required) or hollow (when it is necessary to reduce the weight and/or hydraulic size of the granule).

To increase the porosity of the binder, you can use materials in which the adhesion value between the core and the binder will be no less than the cohesion value of the binder. Then, when the binder dries (shrinks out), under shock load or when heated (if the core of the granule is made of a substance with a coefficient of thermal expansion greater than that of the binder), the granules, the binder will crack, creating additional pores, but will remain attached to the core.

Examples of specific implementation.

An experimental test of the effectiveness of the proposed solution was carried out on a laboratory installation for measuring dynamic sorption capacity, which is a filter column with an internal diameter of 20 mm and a height of 1000 mm, equipped with mesh separators, thermal insulation and a feed gear pump, corrosion-resistant to the test environment. Sorption and desorption were carried out in a downward flow mode. The rate of sorption from the model solution was 5.5 m/h at a brine temperature of 40C, and the rate of desorption by distilled water was 1.5 m/h at a temperature of 20C. The time of the sorption and desorption cycles was constant and amounted to 17 and 6 hours, respectively.

Composition of chloride model brine for test sorption:

Li - 60 mg/l

Na - 24000 mg/l

K - 1000 mg/l

Ca - 8000 mg/l

Mg - 1300 mg/l

The mass content of lithium, sodium, potassium, calcium and magnesium in the eluate (liquid obtained during the desorption cycle) was controlled by capillary electrophoresis (Kapel-105M KEF system).

The studies are illustrated by graphs, where in Fig. 1 shows the results for example 1; in fig. 2 - results for example 2; in fig. 3 - results for example 3; in fig. 4 and 5 - results for example 4; in fig. 6 - results for example 10.

Example 1.

Granular sorbent (granules for sorption of lithium from an aqueous solution) was obtained by coating glass beads of a fraction of 0.5-0.9 mm with a layer of double aluminum-lithium hydroxide in chloride form (DHAL-Cl) 100 μm thick on an inclined mixer-granulator (“Eirich”) using a polymer binder (melamine-formaldehyde resin). The sorbent for application to the glass core (glass bead) was pre-ground in a centrifugal disintegrator to obtain particles with an average size of 10 microns. The amount of binder was 20% of the dry matter weight of the sorbent. The dried granular sorbent with a volume of 250 ml was pre-weighed, soaked in distilled water and placed in a sorption column.

The bulk density of the sorbent is 910 g/l.

The first cycle is the desorption of lithium, which is present in the sorbent upon receipt, with distilled water. The second cycle is the sorption of lithium from brine, the composition of which is the same for all the examples given.

The third cycle is the desorption of lithium accumulated from the model brine with distilled water.

The effectiveness of the sorbent was determined by analyzing the lithium content in the resulting eluate: for each sample, a graph was constructed of the dependence of the lithium content in selected eluate samples on the amount of distilled water passed through (one column volume is the bulk volume of the sorbent taken for the test).

The dynamic capacity of the sorbent (the value of the sorbent capacity under conditions of dynamic sorption/desorption, i.e. at a fixed time of sorption/desorption cycles and a constant flow rate through the sorbent layer), based on the data obtained (Fig. 1), amounted to 12 grams of lithium per kilogram contained in sorbent granules (g/kg).

Example 2.

The granular sorbent was obtained by coating glass beads of various fractions (average size from 0.2 to 3.9 mm) with a layer of double aluminum-lithium hydroxide in chloride form (DGAL-Cl) 100 μm thick on an inclined mixer-granulator (“Eirich”) and using melamine -formaldehyde resin as a binder. The sorbent for application to the glass core was pre-ground in a centrifugal disintegrator to obtain particles with an average size of 10 microns. The amount of binder was 20 wt% on a dry matter basis based on the weight of the sorbent. The dried granular sorbent with a volume of 250 ml was pre-weighed, soaked in distilled water and placed in a sorption column.

The testing methodology is similar to example No. 1.

As a result of testing, the values of the dynamic capacity of granular sorbent of various fractions were obtained (Fig. 2).

The most preferred range of average size of sorbent granules is 0.5 - 1.0 mm. With an average granule size of less than 0.3 mm, the hydraulic resistance of the layer increases significantly; the granules, when contaminated, clump, and the likelihood of material carryover during backwashing also increases. With an average granule size of more than 3.0 mm, the surface area of the granules decreases so much that under conditions of dynamic sorption, the capacity of the sorbent drops below the values appropriate for use.

Example 3.

The granular sorbent was obtained by coating glass beads of a fraction of 0.5-0.9 mm with a layer of double aluminum-lithium hydroxide in chloride form (DHAL-Cl) of varying thickness from 50 to 250 microns on an inclined mixer-granulator (“Eirich”) and using melamine-formaldehyde resin as a binder. The sorbent for application to the glass core was pre-ground in a centrifugal disintegrator to obtain particles with an average size of 10 microns. The amount of binder was 20 wt% on a dry matter basis based on the weight of the sorbent. The dried granular sorbent with a volume of 250 ml was pre-weighed, soaked in distilled water and placed in a sorption column.

The testing methodology is similar to example No. 1.

As a result of testing, the values of the dynamic capacity of a granular sorbent with different sorbent layer thicknesses were obtained (Fig. 3).

The optimal thickness of the sorbent layer is 100 microns. Under conditions of dynamic sorption in a limited time, a layer no more than 150 microns thick effectively participates in sorption. With a further increase in layer thickness, the capacity increases slightly.

Example 4.

The granular sorbent was obtained by coating glass beads of a fraction of 0.5-0.9 mm with a layer of double aluminum-lithium hydroxide in chloride form (DGAL-Cl) 100 microns thick on an inclined mixer-granulator (“Eirich”) and using melamine-formaldehyde resin as a binder . Various sorbent fractions from 5 to 50 µm were used. The sorbent for application to the glass core was pre-ground in a centrifugal disintegrator to the required average particle size. The amount of binder was 20 wt. % by dry matter from the weight of the sorbent. The dried granular sorbent with a volume of 250 ml was pre-weighed, soaked in distilled water and placed in a sorption column.

The testing methodology is similar to example No. 1.

If the average size of sorbent particles exceeds 50 microns, then it is not possible to maintain the optimal thickness of the sorption coating of the core. It is most preferable to use a sorbent with an average particle size of up to 10 microns (Fig. 4). At the same time, obtaining a sorbent with a dispersion of 5 microns or less is very problematic: the grinding time increases and its efficiency decreases. The grinding size begins to be greatly influenced by the degree of washing of DGAL-Cl from accompanying salts (impurities in the synthesis process).

The values of abrasion of sorbent granules were also measured according to GOST R 51641-2000 (Fig. 5).

The graph shows that as the grind size increases, the mechanical strength of the sorbent layer sharply decreases. Therefore, the average particle size of the sorbent should not exceed 50 microns. It is optimal if the average size of sorbent particles does not exceed 10 microns.

Example 5.

The granular sorbent was obtained by coating balls of melamine-formaldehyde resin of fraction 0.5-0.9 mm with a layer of double aluminum-lithium hydroxide in chloride form (DGAL-Cl) 100 microns thick on an inclined mixer-granulator (“Eirich”) and using melamine formaldehyde resin as a binder. The sorbent for application to the polymer core was pre-ground in a centrifugal disintegrator to obtain particles with an average size of 10 μm. The amount of binder was 20% of the dry matter weight of the sorbent. The dried granular sorbent with a volume of 250 ml was pre-weighed, soaked in distilled water and placed in a sorption column.

Among all the types of cores used, granules with a melamine-formaldehyde core provide maximum strength to the surface layer due to the adhesion of the binder to the core. Since the core material and the binder are the same polymer with the same set of functional groups, when drying the granules, the amino groups of the prepolymer are cross-linked not only in the volume of the sorbent layer, but also with the surface of the core. As a result, it is possible to repeatedly backwash the granular sorbent without destroying the granules.

The testing methodology is similar to example No. 1.

The dynamic capacity of the sorbent for lithium was (13.5 g/kg). The bulk density of the sorbent decreased to 750 g/l.

The increase in the dynamic capacity of the sorbent is due to a change in the morphology of the sorbent surface, namely the appearance of microcracks due to shrinkage of the binder during drying.

Example 6.

The granular sorbent was obtained by coating glass spheres of the 0.3-0.7 mm fraction with a layer of double aluminum-lithium hydroxide in chloride form (DGAL-Cl) 100 μm thick on an inclined mixer-granulator (“Eirich”) and using melamine-formaldehyde resin as a binder . The amount of binder was 20% of the dry matter weight of the sorbent.

The dynamic capacity of the sorbent, based on the data obtained, was 14.85 g/kg. The bulk density of the sorbent using a hollow core decreased to 390 g/l.

Example 7.

The sorbent was obtained by granulating double aluminum-lithium hydroxide in chloride form (DHAL-Cl) on an inclined mixer-granulator (“Eirich”) and using melamine-formaldehyde resin as a binder. The amount of binder was 20% of the dry matter weight of the sorbent. Target sorbent fraction for testing: 0.6-1.0 mm.

The dynamic capacity of the sorbent was 7.1 g/kg. The bulk density of the solid sorbent was 800 g/l. The inner part of the granule practically does not take part in the extraction process and is “ballast”. Comparing the sorption capacity of a granule on a glass core from example No. 1 and a solid granule, it becomes obvious that the thickness of the effective sorbent layer is about 100 microns.

Example 8.

The granular sorbent was obtained by coating a silicate porous core (granulated and calcined tripoli) fraction 0.5-0.9 mm with a layer of double aluminum-lithium hydroxide in chloride form (DHAL-Cl) 100 μm thick on an inclined mixer-granulator (“Eirich”) with using a polymer binder (melamine-formaldehyde resin). The sorbent for application to the porous core was pre-ground in a centrifugal disintegrator to obtain particles with an average size of 10 microns. The amount of binder was 20% of the dry matter weight of the sorbent.

The bulk density of the sorbent was 740 g/l. The dynamic sorption capacity for lithium turned out to be significantly lower than expected and amounted to 6.3 g/kg. This is due to the penetration of the primary brine into the porous core and an increase in the mineralization of the eluate during the subsequent desorption of lithium. As mineralization increases, the desorption rate decreases, which affects the dynamic capacity of the sorbent. Also, the resulting eluate contains a larger amount of impurities than when using a granule with a waterproof core.

Example 9.

The granular sorbent was obtained by coating glass beads of a fraction of 0.5-0.9 mm with a layer of double aluminum-lithium hydroxide in chloride form (DHAL-Cl) with a thickness of 100 microns on an inclined mixer-granulator (“Eirich”) using a solution of a hydrophobic polymer binder (polyvinyl chloride in dichloromethane). The sorbent for application to the glass core (glass bead) was pre-ground in a centrifugal disintegrator to obtain particles with an average size of 10 microns. The amount of binder was 20% of the dry matter weight of the sorbent. The dried granular sorbent with a volume of 250 ml was pre-weighed, soaked in distilled water and placed in a sorption column. Then 10 liters of water-oil emulsion with an oil product concentration of 300 mg/l was passed through the column. Next, sorption/desorption cycles were carried out similarly to step 1.

When using PVC as a binder and in the presence of petroleum products, the capacity of the sorbent is reduced due to the sorption of petroleum products on the surface of granules. For this type of granules, the sorption capacity was 4.3 g/l, which corresponds to a drop in sorption capacity by 64.2%.

Granules from examples 1 and 3 were tested in a similar way. For a granular sorbent on a glass core using a melamine-formaldehyde binder, exposure to petroleum products reduced the sorption capacity by 11.2%: from 12 to 10.7 g/kg. For a granular sorbent on a glass core with the addition of tripoli, the sorption capacity decreased by 3.6%: from 12 to 11.7 g/kg.

Example 10.

The granular sorbent was obtained by coating glass beads of the 0.5-0.9 mm fraction with a layer of double aluminum-lithium hydroxide in chloride form (DGAL-Cl) with a thickness of 100 microns on an inclined mixer-granulator (“Eirich”) using a polymer binder (melamine-formaldehyde resin ). The sorbent for application to the glass core (glass bead) was pre-ground in a centrifugal disintegrator to obtain particles with an average size of 10 microns. The amount of binder ranged from 10 to 60 wt.% dry matter based on the weight of the sorbent. The dried granular sorbent with a volume of 250 ml was pre-weighed, soaked in distilled water and placed in a sorption column.

As the amount of binder increases, the porosity of the layer decreases and the diffusion limitations of the sorption/desorption processes for the internal volume of the sorbent increase. This leads to a sharp decrease in the dynamic sorption capacity of the granules when the amount of binder increases to more than 40 wt. % (Fig. 6).

Example 11.

The granular sorbent was obtained by coating glass beads of the 0.5-0.9 mm fraction with a layer of double aluminum-lithium hydroxide in chloride form (DGAL-Cl) with a thickness of 100 microns on an inclined mixer-granulator (“Eirich”) using a polymer binder (melamine-formaldehyde resin ). The sorbent for application to the glass core (glass bead) was pre-ground in a centrifugal disintegrator to obtain particles with an average size of 100 and 50 microns. The amount of binder was 20% of the dry matter weight of the sorbent.

When using sorbent granules with particle sizes of 100 and 50 microns for rolling, it is not possible to obtain an economically feasible yield of the required granule fraction. In granulation products, the content of granules without a glass core, agglomerates of several granules with a core of large DGAL-Cl particles, and granules on a glass core with extremely low sphericity (unevenness of the coating of the core) sharply increases. The resulting granulation products are difficult to recycle and increase the cost of the sorbent.

The conducted studies show that the use of the proposed solution increases the efficiency of the process of sorption of lithium from oil-, fat-, oil-contaminated aqueous solution and desorption of lithium from granules due to: adding a core to the granule; expanding the range of filtration speed of solution and washing liquid through a layer of granular sorbent; and preventing contamination of sorbent granules with oil, fat, and petroleum components of the aqueous solution.

Claims (10)

1. A granule for the sorption of lithium from an aqueous solution containing sorbent particles from a chlorine-containing variety of double hydroxide of aluminum and lithium, characterized in that the granule contains a waterproof spherical core coated with a solution-permeable composite of sorbent particles and a hydrophilic binder, and the hydrophilic binder has an open-porous structure . 2. Granule according to claim 1, characterized in that the maximum binder content in terms of dry residue is no more than 40% of the mass of sorbent particles. 3. Granule according to claim 1, characterized in that the average size of the granules is not less than 0.3 mm and not more than 3.0 mm, preferably not less than 0.5 mm and not more than 1.0 mm. 4. Granule according to claim 1, characterized in that the average particle size of the sorbent does not exceed 50 microns, preferably 10 microns. 5. Granule according to claim 1, characterized in that the average thickness of the sorption coating of the core does not exceed 150 microns, preferably 100 microns. 6. Granule according to claim 1, characterized in that the granule is covered with a protective layer of tripoli with an average particle size of no more than 10 microns. 7. Granule according to claim 1, characterized in that the core is made of glass. 8. Granule according to claim 1, characterized in that the core is made of a binder. 9. Granule according to claim 1, characterized in that the core of the granule is hollow. 10. Granule according to claim 1, characterized in that the value of adhesion between the core and the binder is not less than the value of cohesion of the binder.