Method for obtaining a lithium concentrate from a lithium-containing solution by sorption

Abstract

The proposed invention relates to a method for extracting lithium from lithium-containing solutions, including natural brines and waters, process solutions and wastewater from various industries. Proposed is a method for obtaining a lithium concentrate from a lithium-containing solution, which includes a sorption step that comprises passing a lithium-containing solution through a sorbent for extracting lithium from lithium-containing solutions which is based on a chlorine-containing form of an aluminium-lithium double hydroxide, and a desorption step, wherein the sorption step is preceded by a step for removing iron and manganese from the lithium-containing solution, and the sorbent used in the sorption step does not have paramagnetic properties. The technical result of the claimed invention is that of improving the sorption-based process of lithium extraction.

Description

[0001] METHOD FOR SORPTION OBTAINING LITHIUM CONCENTRATE FROM A LITHIUM-CONTAINING SOLUTION

[0002] Field of technology

[0003] The proposed invention relates to a method for extracting lithium from lithium-containing solutions, including natural brines and waters, process solutions and wastewater from various industries.

[0004] Prior art

[0005] Patent RU2763955, published on January 11, 2022, discloses a method for the sorption extraction of lithium from lithium-containing brines. The method involves feeding the initial lithium-containing brine into a sorption-desorption enrichment module, which comprises at least one vertically mounted column filled with an inorganic granular sorbent, which is a chlorine-containing double aluminum lithium hydroxide. Following the sorption stage, before washing, the remaining lithium-containing brine is drained from the column. Washing is carried out at a rate of at least 6 column volumes per hour, in a volume equal to 150-250% of the sorbent volume in the column, in a direction coinciding with the feed direction of the initial lithium-containing brine. Then, lithium is desorbed from the sorbent using demineralized water in a direction that coincides with the direction of supply of the initial lithium-containing brine, resulting in a lithium-enriched solution.The resulting solution, containing practically pure lithium chloride, is subjected to evaporation or other concentration methods.

[0006] A disadvantage of the above-mentioned invention is the reduction in the sorbent's capacity during the sorption extraction of lithium from lithium-containing solutions due to clogging of the sorbent's pores or interchannel space by iron and manganese impurities that precipitate during the process. This effect leads to a reduction in the available surface area for lithium sorption and, consequently, to a decrease in the extraction efficiency.

[0007] Disclosure of invention

[0008] The objective of the present invention is to develop an efficient method for processing a lithium-containing solution.

[0009] The technical result of the claimed invention consists in improving the process of sorption extraction of lithium.

[0010] The technical result from the implementation of the claimed invention includes:

[0011] - increasing the capacity of the sorbent; - increasing the service life;

[0012] - improvement of the hydrodynamic characteristics of the sorbent.

[0013] In addition, the use of the claimed method allows:

[0014] - increase the sorbent capacity to 6 g / l;

[0015] - improve the hydrodynamic characteristics of the sorbent (kPa h / m 2 , pressure drop per 1 m of sorbent height at a linear velocity of 1 m / h).

[0016] To solve the problem and achieve the technical result, it is proposed.

[0017] A method for the sorption production of lithium concentrate from a lithium-containing solution, comprising the following stages:

[0018] - sorption, which involves passing a lithium-containing solution through a sorbent to extract lithium from lithium-containing solutions based on a chlorine-containing form of double aluminum hydroxide and lithium,

[0019] - desorption,

[0020] characterized in that

[0021] Before the sorption stage, a stage of removing iron and manganese from the lithium-containing solution is carried out, and for the sorption stage, a sorbent that does not have paramagnetic properties is used.

[0022] In their lithium sorption studies, the authors aimed to develop a universal lithium sorption method suitable for various types of lithium-containing solutions using a sorbent based on a chloride-containing form of aluminum lithium double hydroxide. During these studies, the authors encountered relatively low capacity, service life, and hydrodynamic properties with some sorbent brands. These deviations from expected results prompted the authors to further investigate the causes of the sorbent capacity decline.

[0023] The authors conducted EPR (electron paramagnetic resonance) studies of sorbent samples and unexpectedly discovered that samples exhibiting increased sorbent life without loss of capacitive properties had paramagnetic properties. Specifically, resonant absorption of microwave radiation was observed in the magnetic field strength range of 3500-3520 mT. However, the remaining DGAL-C1 sorbents, as well as the binder, did not exhibit paramagnetic properties. Sorbents without paramagnetic properties exhibited poorer performance (capacity, service life, and hydrodynamic characteristics) relative to paramagnetic sorbents. The authors suggest that the decrease in sorbent capacitive properties during the sorption extraction of lithium from lithium-containing solutions occurs due to clogging of the sorbent pores or interchannel space by iron and manganese impurities that precipitate during the process.This effect can lead to a reduction in the available surface area for lithium sorption and, as a consequence, to a decrease in the efficiency of the process.

[0024] Due to the technology used for synthesizing a sorbent with paramagnetic properties, the sorbent has reducing (antioxidant) properties, which prevents the oxidation of soluble forms of iron and manganese and the formation of precipitates that block the pores of the sorbent.

[0025] The reducing properties of the sorbent are not a consequence of paramagnetism, but are a related property due to the synthesis technology used.

[0026] After reviewing various industrial methods for removing iron and manganese, the authors concluded that these methods do not take into account the specifics of the lithium sorption process. Known methods for removing these impurities are typically used in other areas of technology and are not considered necessary preliminary steps for lithium sorption.

[0027] The above conditions are sufficient to achieve the technical result, and the following preferred options allow for more complete use of all the advantages of the claimed invention:

[0028] Preferably, the stage of iron and manganese removal may include the stages of oxidation, coagulation and filtration of impurities;

[0029] Preferably, after the filtration stage, an ultrafiltration stage is carried out; Preferably, the oxidation of impurities is carried out by adding at least one of the following oxidizing agents: potassium permanganate, bleach, sodium hypochlorite, hydrogen peroxide, or by passing the initial solution through a catalytic load based on Mn oxide, or by carrying out oxidation using the ozonation method;

[0030] Preferably, potassium permanganate is added in an amount of 1 to 5 g / l, sodium hypochlorite - from 2 to 10 g / l, bleach - from 1 to 20 g / l, hydrogen peroxide - from 1 to 20 g / l.

[0031] Preferably, ozonation is carried out at an ozone concentration of 1 to 5 mg / l and a contact time of 15 to 30 minutes. Preferably, coagulation of impurities is carried out by adding at least one of the following: iron chloride, aluminum sulfate, polyaluminum chloride, polyacrylamide.

[0032] Preferably, iron chloride or aluminum sulfate, or polyaluminum chloride or polyacrylamides are added in an amount of 1-50 mg / l, preferably 1-25 mg / l.

[0033] Preferably, prior to the ultrafiltration stage, filtration is carried out using at least one of the following:

[0034] - on a filter press

[0035] - passing the solution through bulk filters:

[0036] - passing the solution through a catalytic bed;

[0037] - passing the solution through diatomaceous earth filters or silica gel filters. Ultrafiltration is preferably performed at pressures up to 10 bar using membranes with a porosity of 0.01 µm.

[0038] In natural and industrial solutions, iron and manganese are often found in dissolved form as divalent ions (Fe 2+ and MP 2+). These ions are difficult to remove by traditional filtration methods. The oxidation process converts them into insoluble forms (Fe(OH)3 and Mn3SO4, Mn2O3), which can be precipitated. For example, the addition of oxidizing agents such as chlorine, potassium permanganate, or ozone promotes the conversion of Fe(II) to Fe(III) and Mn(II) to Mn(III) and Mn(IV). After oxidation, iron hydroxides and manganese oxides are formed, which are in the form of small suspended particles. These particles tend to remain in solution and not settle. Coagulation helps aggregate these small particles into larger floccules, which are easier to remove. Coagulants such as ferric or aluminum chloride promote the formation of large precipitates, accelerating their subsequent removal. After oxidation and coagulation, insoluble iron and manganese compounds are formed as a precipitate. These precipitates must be removed from the solution to prevent them from entering the sorption columns.Filtration through press filters or granular filters, such as activated carbon, sand, or diatomaceous earth filters, effectively removes these precipitates, purifying the solution and preventing clogging of the sorbent pores. Filtration also removes any remaining fine particles, and when combined with ultrafiltration, it ensures high solution purity before lithium sorption. Thus, the use of oxidation, coagulation, filtration, and ultrafiltration stages effectively removes iron and manganese impurities from lithium-containing solutions, increasing the efficiency and longevity of sorption processes for lithium extraction.

[0039] Implementation of the invention. The best embodiment of the invention. Preparation of the initial solution:

[0040] The initial lithium-containing solution undergoes preliminary purification to remove coarse impurities and mechanical suspensions.

[0041] Oxidation:

[0042] To remove dissolved iron and manganese, the initial solution is oxidized. Sodium hypochlorite, an oxidizing agent, is added to the solution at a rate of approximately 5 g / L until the oxidizing agent concentration reaches a level that ensures complete oxidation of the iron and manganese. The reaction is carried out at a temperature of 20-25 °C and a pH of 5-7, converting Fe(II) to Fe(III) and Mn(II) to Mn(III) and Mn(IV).

[0043] Coagulation:

[0044] After oxidation, a coagulant—ferric chloride (FeCh)—is added to the solution at a concentration of 1-10 mg / L. This results in the formation of large floccules of iron and manganese hydroxides.

[0045] Ferric chloride (iron hydroxide formed from chloride in a neutral environment) is a powerful coagulant that effectively aggregates small particles and colloids, creating large floccules that can then be easily removed by filtration. This is especially important for removing finely dispersed iron and manganese impurities from solutions.

[0046] Filtration on press filters:

[0047] The resulting mixture is filtered using press filters to remove the formed floccules and precipitated iron and manganese impurities.

[0048] Ultrafiltration:

[0049] The clear filtrate passes through an ultrafiltration system to remove any remaining fine particles and colloids. The ultrafiltration process is carried out at pressures up to 10 bar using membranes with a porosity of 0.01 µm.

[0050] The stages of sorption and desorption are carried out using known methods.

[0051] The hydrodynamic characteristics were measured after passing a volume of 1000 KO of hydromineral raw material at a specific load of 3 KO / h. At the beginning of the experiment, the pressure drop per meter of sorbent was 0.2 kgf / cm 2 , at a linear velocity of 10 m / h. After the experiment, the pressure drop per meter of sorbent was 0.5 kgf / cm 2 without preliminary precipitation of Fe and Mn.

[0052] The following examples are non-limiting and illustrate the feasibility of implementing the invention. The experimental results are presented in the table:

[0053]

Claims

Invention formula 1. A method for the sorption production of lithium concentrate from a lithium-containing solution, comprising the following stages: - sorption, which involves passing a lithium-containing solution through a sorbent to extract lithium from lithium-containing solutions based on a chlorine-containing form of double aluminum hydroxide and lithium, - desorption, characterized in that Before the sorption stage, a stage of removing iron and manganese from the lithium-containing solution is carried out; for the sorption stage, a sorbent that does not have paramagnetic properties is used; 2. The method according to item 1, characterized in that the stage of removing iron and manganese may include the stages of: oxidation, coagulation and filtration of impurities; 3. The method according to item 2, characterized in that after the filtration stage, an ultrafiltration stage is carried out; 4. The method according to item 2, characterized in that the oxidation of impurities is carried out by adding at least one of the following: potassium permanganate, bleach, sodium hypochlorite, hydrogen peroxide, or by passing the initial solution through a catalytic load based on Mn oxide, or by carrying out oxidation using the ozonation method; 5. The method according to item 4, characterized in that potassium permanganate is preferably added in an amount of 1 to 5 g / l, sodium hypochlorite - from 2 to 10 g / l, bleach - from 1 to 20 g / l, hydrogen peroxide - from 1 to 20 g / l; 6. The method according to item 4, characterized in that ozonation is preferably carried out at an ozone concentration of 1 to 5 mg / l and a contact time of 15 to 30 minutes; 7. The method according to item 2, characterized in that the coagulation of impurities is carried out by adding at least one of the following: iron chloride, aluminum sulfate, polyaluminum chloride, polyacrylamide 8. The method according to item 7, characterized in that iron chloride or aluminum sulfate, or polyaluminum chloride or polyacrylamides are preferably added in an amount of 1-50 mg / l, more preferably 1-25 mg / l; 9. The method according to item 2, characterized in that the filtration is carried out using at least one of the following: - on a filter press; - by passing the solution through bulk filters; - by passing the solution through a catalytic bed; - by passing the solution through diatomaceous earth filters; - by passing the solution through filters with silica gel; 10. The method according to item 3, characterized in that ultrafiltration is carried out at a pressure of up to 10 bar using membranes with a porosity of 0.01 µm.

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