Process and apparatus for producing lithium carbonate from a lithium-containing solution

Abstract

The proposed invention relates to a process for producing lithium carbonate from a lithium-containing solution and to an apparatus for carrying out same. What is proposed is a process for producing lithium carbonate from a lithium-containing solution which comprises the steps of: (a) sorbing and desorbing a lithium-containing solution to obtain an eluate; (b) obtaining from the eluate a concentrate that is purified of impurities. Step (b) includes a step (b1) of concentrating the eluate by reverse osmosis to obtain a concentrate and a permeate. The permeate from step (b1) is collected in a tank until the conductivity value of the permeate lies within a range of 10-600 µS / cm, then the permeate is sent to step (a) for desorption. In an alternative embodiment, the permeate from step (b1) is collected in a tank until the concentration of lithium salts in the permeate lies within a range of 0.01-50 mg / L in terms of elemental lithium, then the permeate is sent to step (a) for desorption. The technical result of the invention is an increase in the efficiency of the lithium production process, high lithium recovery from lithium-containing solutions, and also from solid lithium recovery process waste, and the production of battery-grade lithium carbonate, as well as longer term sorbent efficiency, i.e. an increase in the service life of the sorbent.

Description

[0001] METHOD AND APPARATUS FOR PRODUCING LITHIUM CARBONATE 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] The disadvantage of the above invention is the insufficient extraction of lithium, in particular the problem of removing lithium from the process with solid waste has not been solved.

[0007] Patent RU2816073, published on March 26, 2024, discloses a method for the sorption production of lithium concentrate from a lithium-containing solution, which comprises: an sorption step, including passing the lithium-containing solution through a sorbent to extract lithium, a step for washing said sorbent, and a desorption step. During the sorbent washing step, a washing liquid containing a depleted raffinate and / or a depleted eluate is used for washing. The depleted raffinate is a solution collected from the first 0.4-1.5 column volumes of the solution obtained in the sorption step as a result of contact between the lithium-containing brine and said sorbent. The depleted eluate is a solution taken from any of the 4th, 5th, 6th, 7th or 8th column volumes of the solution obtained at the desorption stage as a result of contact of the desorbing solution with the specified sorbent.

[0008] The disadvantage of the above invention is the insufficient extraction of lithium, in particular the problem of removing lithium from the process with solid waste has not been solved.

[0009] The closest analog is patent RU2720420C1, published on April 29, 2020, which discloses a method for the sorption extraction of lithium from lithium-containing brines, in which:

[0010] - lithium concentrate is obtained by sorption enrichment of brine for lithium in a sorption-desorption enrichment module using a granulated sorbent based on a chlorine-containing variety of double aluminum and lithium hydroxide;

[0011] - wash the granulated sorbent saturated with lithium chloride from the brine;

[0012] - desorption of lithium chloride from the sorbent is carried out to obtain a primary lithium concentrate - a solution of lithium chloride with impurities of magnesium and calcium;

[0013] - primary lithium concentrate is sent to a nanofiltration unit that is selective with respect to magnesium and calcium;

[0014] The concentrate from the nanofiltration unit is recycled back into the original lithium-containing brine stream. The filtrate from the nanofiltration unit is sent for subsequent concentration for lithium chloride.

[0015] A disadvantage of the above-mentioned invention is its insufficient lithium recovery, as the conventional nanofiltration concentrate stream contains not only calcium and magnesium but also a significant amount of lithium. In fact, 40-50% of the lithium obtained after the sorption stage is recycled back into the sorption process after the nanofiltration stage. This significantly reduces lithium recovery efficiency, placing additional strain on the sorption module. Additional disadvantages of the above-mentioned invention include the limited lifespan of the nanofiltration membranes and the increased costs of their washing and regeneration.

[0016] In this application: mixing (blend) — adding one component to another; mother liquor — liquid phase (liquid) after separation of precipitate from it; eluate — solution obtained during desorption of extracted component (lithium); raffinate — solution obtained during sorption of extracted component (lithium); permeate (filtrate) — flow of substance passing through semipermeable membrane during membrane separation; concentrate — solution having lithium concentration higher than lithium concentration in solution at previous process stage; concentrate purification from impurities — at least partial removal of impurities from concentrate. After such procedure concentrate is considered purified from impurities even if some amount of impurities remains in it; eluate purification from impurities — at least partial removal of impurities from eluate.After this procedure, the eluate is considered purified of impurities, even if some impurities remain. A solution is a homogeneous mixture of substances, and incomplete dissolution of one substance in another does not preclude the fact that a solution has been obtained for the portion that is completely dissolved. Thus, a solution containing precipitate may be present in a container simultaneously with undissolved precipitate; this does not preclude the presence of the solution and its subsequent processing.

[0017] The objective and technical result of the present invention are to increase the efficiency of the lithium production process, achieve high lithium recovery from lithium-containing solutions, including solid waste from the lithium extraction process, produce battery-grade lithium carbonate, and extend the effective life of the sorbent (increase the service life of the sorbent). In one embodiment, to solve the stated objective and achieve the technical result, a method for producing lithium carbonate from a lithium-containing solution is proposed, comprising the following steps:

[0018] (a) sorption and desorption of a lithium-containing solution to obtain an eluate;

[0019] (b) obtaining a concentrate from the eluate purified from impurities; wherein step (b) includes a step (Y) of reverse osmosis concentration of the eluate to obtain a concentrate and permeate; characterized in that the permeate from step (Y) is collected in a container until its conductivity reaches a value in the range of 10-600 μS / cm, and then the permeate is sent for desorption at step (a).

[0020] The above conditions made it possible to increase the efficiency of the lithium production process, ensure high lithium extraction from lithium-containing solutions, obtain battery-grade lithium carbonate, and also increase the effective service life of the sorbent (increase the service life of the sorbent).

[0021] Directing the permeate with the specified parameters to desorption at stage (a) allows for an increase in the service life of the sorbent by reducing the degree of lithium leaching from the upper part of the working zone of the columns with the sorbent, thereby ensuring that the leaching effect does not occur below the critical limit, which does not lead to its degradation.

[0022] The above steps themselves are known in the art and are therefore described in general terms. The present invention consists of implementing such a sequence of actions using known units, which results in an unexpected and unanticipated increase in the efficiency of the lithium production process.

[0023] The above stages can be carried out by means known to a specialist, while the particular variants of implementing the stages indicated below make it possible to achieve the stated technical result in the most effective way.

[0024] Preferably, the permeate from step (Y) is collected in a vessel until its conductivity reaches a range of 20-600 μS / cm, most preferably 40-600 μS / cm, and then sent for desorption at step (a). This further extends the service life of the sorbent by reducing the degree of lithium leaching from the upper portion of the working zone of the sorbent columns. This ensures that leaching does not occur below a critical limit, preventing its degradation.

[0025] In another embodiment, to solve the stated problem and achieve the technical result, a method for obtaining lithium carbonate from a lithium-containing solution is proposed, which includes the following stages:

[0026] (a) sorption and desorption of a lithium-containing solution to obtain an eluate;

[0027] (b) obtaining from the eluate a concentrate purified from impurities; wherein step (b) includes step (Y) of reverse osmosis concentration of the eluate to obtain a concentrate and permeate; characterized in that the permeate from step (Y) is collected in a container until the concentration of lithium salts in it reaches a range of 0.01-50 mg / l in terms of elemental lithium, and then the permeate is sent for desorption at step (a).

[0028] The above conditions made it possible to increase the efficiency of the lithium production process, ensure high lithium extraction from lithium-containing solutions, obtain battery-grade lithium carbonate, and also increase the effective service life of the sorbent (increase the service life of the sorbent).

[0029] Directing the permeate with the specified parameters to desorption at stage (a) allows for an increase in the service life of the sorbent by reducing the degree of lithium leaching from the upper part of the working zone of the columns with the sorbent, thereby ensuring that the leaching effect does not occur below the critical limit, which does not lead to its degradation.

[0030] Preferably, the permeate from step (Y) is collected in a container until the concentration of lithium salts in it reaches a range of 0.1-50 mg / l in terms of elemental lithium, most preferably 10-50 mg / l in terms of elemental lithium, and then the permeate is sent for desorption at step (a).

[0031] This further extends the service life of the sorbent by reducing the rate of lithium leaching from the upper portion of the working zone of the sorbent columns. This prevents leaching below a critical limit, preventing degradation. Preferably, stage (Y) produces a concentrate with an electrical conductivity of 16,000-60,000 µS / cm.

[0032] This allows the desired lithium concentration to be achieved with a lower load on the evaporation unit, thereby saving energy costs.

[0033] Preferably, after step (b), step (c) of precipitating the concentrate to obtain a precipitate and a mother liquor, and separating the precipitate and the mother liquor is carried out; wherein the mother liquor from step (c) is fed for mixing with the lithium-containing solution before being fed to step (a).

[0034] Directing the above-mentioned mother liquor for mixing with a lithium-containing solution fed to the sorption and desorption stage allows for an increase in the degree of lithium extraction while maintaining a long service life of the sorbent.

[0035] Preferably, before feeding the mother liquor from step (c) for mixing with the lithium-containing solution, the pH of the mother liquor is adjusted to 1.01-3, preferably to 1.3-2.5, more preferably to 1.4-2.0, most preferably to 1.9.

[0036] When the pH of the mother liquor is less than 1.01, there is an excessive consumption of acid used to regulate (adjust) the pH of the mother liquor.

[0037] At a pH greater than 1.01 and less than 3, precipitation is eliminated when mixing the concentrate with hydromineral raw materials, and the service life of the sorbent is further increased.

[0038] The authors of the invention associate the above-mentioned effect with a reduction in the residual carbonate and bicarbonate anions, the insoluble salts of which can precipitate in the pores of the sorbent, which makes it possible to further increase the service life of the sorbent and increase the degree of lithium extraction.

[0039] The above preferred pH ranges can further extend the service life of the sorbent and increase the degree of lithium extraction.

[0040] Preferably, the pH of the mother liquor from step (c) is adjusted to the specified value by adding hydrochloric acid.

[0041] The pH can be adjusted (brought to the desired value) by any means known in the art, but hydrochloric acid is preferably used for this purpose. Preferably, in step (c), the concentrate is precipitated in a reactor, wherein the concentrate is heated to 75°-95°, preferably to 80°-95°, most preferably to 85°-95°, and maintained under stirring for 20-60 minutes, preferably 30-50 minutes, most preferably 30-40 minutes.

[0042] Heating the concentrate to the specified temperature and holding it for the specified period during stirring allows for an additional increase in the degree of lithium extraction and an increase in the equipment utilization rate.

[0043] Preferably, in step (c), the separation of the precipitate and the mother liquor is carried out in a centrifuge.

[0044] Instead of a centrifuge, you can use a Nutsche filter, press filters, a combination of both, or any other solid-liquid filtration equipment. However, using centrifuges can further improve the efficiency of the lithium extraction process.

[0045] Preferably, in step (a), a sorbent based on a chlorine-containing variety of double aluminum and lithium hydroxide is used.

[0046] This allows for maximum use of all the advantages of the claimed invention.

[0047] Preferably, step (b) after step (Y) includes step (b2) of purifying the concentrate from impurities.

[0048] Preferably, after step (Ы) and before step (Ь2), the concentrate is evaporated, and the distillate obtained during evaporation is used to prepare the reagents used in step (c) and / or step (Ь2).

[0049] Evaporation means reducing the amount (volume) of concentrate by evaporating excess liquid.

[0050] Directing the distillate to prepare the reagents used in stage (c) and / or stage (b2) allows for further improvement of the efficiency of the lithium production process by reducing water consumption and energy consumption of the technology.

[0051] Preferably, in step (b2), a precipitate containing impurities is separated from the concentrate and a solution containing said precipitate is obtained, wherein the pH value of said solution is adjusted to 1-3, preferably 1.01-2, most preferably 1.01-1.3, and this solution is fed for mixing with the lithium-containing solution before feeding it to step (a).

[0052] At pH less than 1, excessive acid consumption occurs.

[0053] At a pH of less than 3, precipitation is eliminated when mixing the concentrate with hydromineral raw materials, and the service life of the sorbent is additionally increased.

[0054] The authors of the invention associate this effect with a reduction in the residual carbonate and bicarbonate anions, the insoluble salts of which can precipitate in the pores of the sorbent.

[0055] The above mentioned narrower pH ranges allow to further increase the service life of the sorbent.

[0056] This also allows for an additional increase in the throughput of lithium extraction and the elimination of solid production waste.

[0057] Preferably, at step (b2), before separating the precipitate containing impurities from the concentrate, a sodium hydroxide solution is added to the concentrate until a pH value in the range of 10-12 is reached, and sodium carbonate is also added and mixed.

[0058] The eluate can be purified from Ca and Mg impurities using any known methods or combinations thereof, including the use of sorption technologies for the removal of Ca and Mg, or using reagents for the removal of Ca and Mg impurities, including through ion binding processes. However, the above method allows for an additional increase in the throughput of lithium extraction and the elimination of solid production waste.

[0059] Preferably, the pH of the solution obtained by dissolving the precipitate in step (b2) is adjusted to the specified value by adding hydrochloric acid.

[0060] The pH can be adjusted using any means known in the art, but it is preferable to use hydrochloric acid for this purpose.

[0061] Preferably, step (b) before step (Y) includes step (bG) of purifying the eluate from impurities.

[0062] Preferably, at step (bG), a precipitate containing impurities is separated from the eluate and a solution containing said precipitate is obtained, wherein the pH value of said solution is adjusted to 1-3, preferably 1.01-2, most preferably 1.01-1.3, and this solution is fed for mixing with the lithium-containing solution before feeding it to step (a).

[0063] At pH less than 1, excessive acid consumption occurs.

[0064] At a pH of less than 3, precipitation is eliminated when mixing the concentrate with hydromineral raw materials, and the service life of the sorbent is additionally increased.

[0065] The authors of the invention associate this effect with a reduction in the residual carbonate and bicarbonate anions, the insoluble salts of which can precipitate in the pores of the sorbent.

[0066] The above mentioned narrower pH ranges allow to further increase the service life of the sorbent.

[0067] This also allows for an additional increase in the throughput of lithium extraction and the elimination of solid production waste.

[0068] Preferably, at step (ЬГ), before separating the precipitate containing impurities from the eluate, a sodium hydroxide solution is added to the eluate until a pH value in the range of 10-12 is reached, and sodium carbonate is also added and mixed.

[0069] The eluate can be purified from Ca and Mg impurities using any known methods or combinations thereof, including the use of sorption technologies for the removal of Ca and Mg, or using reagents for the removal of Ca and Mg impurities, including through ion binding processes. However, the above method allows for an additional increase in the throughput of lithium extraction and the elimination of solid production waste.

[0070] Preferably, at step (bG), a precipitate containing impurities is separated from the eluate, while at step (b2), a precipitate containing impurities is separated from the concentrate, wherein said precipitates are dissolved to obtain a mixed solution, the pH of which is adjusted to 1-3, preferably 1.01-2, most preferably 1.01-1.3, and this mixed solution is fed for mixing with the lithium-containing solution before feeding it to step (a).

[0071] A pH below 1 results in excessive acid consumption. A pH below 3 prevents precipitation when mixing the concentrate with hydromineral raw materials and further extends the service life of the sorbent.

[0072] The authors of the invention associate this effect with a reduction in the residual carbonate and bicarbonate anions, the insoluble salts of which can precipitate in the pores of the sorbent.

[0073] The above mentioned narrower pH ranges allow to further increase the service life of the sorbent.

[0074] This also allows for an additional increase in the throughput of lithium extraction and the elimination of solid production waste.

[0075] Preferably, at step (ЬГ), before separating the precipitate containing impurities from the eluate, a sodium hydroxide solution is added to the eluate until a pH value in the range of 10-12 is reached, and sodium carbonate is also added and mixed, while at step (Ь2), before separating the precipitate containing impurities from the concentrate, a sodium hydroxide solution is added to the concentrate until a pH value in the range of 10-12 is reached, and sodium carbonate is also added and mixed.

[0076] The eluate and concentrate can be purified from Ca and Mg impurities using any known methods or combinations thereof, including the use of sorption technologies for the removal of Ca and Mg, or using reagents for the removal of Ca and Mg impurities, including through ion binding processes. However, the above method allows for an additional increase in the throughput of lithium extraction and the elimination of solid production waste.

[0077] Preferably, after step (Ы) and before step (Ь2), the concentrate is evaporated, and the distillate obtained during evaporation is used to prepare the reagents used in step (c) and / or step (ЬГ) and / or step (Ь2).

[0078] Directing the distillate for the preparation of reagents used in stage (c) and / or stage (ЬГ) and / or stage (Ь2) makes it possible to further increase the efficiency of the lithium production process by reducing water consumption and energy consumption of the technology.

[0079] Preferably, the pH of the solution obtained by dissolving the precipitate is adjusted to the specified value by adding hydrochloric acid. pH adjustment can be done by any means known in the art, but hydrochloric acid is preferred.

[0080] In one embodiment, to solve the stated problem and achieve the technical result, a plant for producing lithium carbonate from a lithium-containing solution is proposed, including:

[0081] (a) a unit for sorption and desorption of a lithium-containing solution, configured to remove the eluate;

[0082] (b) a unit for obtaining from the eluate a concentrate purified from impurities; wherein the unit (b) includes (N) a unit for reverse osmosis concentration of the eluate with the production of a concentrate and permeate, characterized in that the installation is designed with the possibility of collecting the permeate from the unit (N) in a container until its conductivity reaches a value in the range of 10-600 μS / cm.

[0083] Preferably, the installation is designed with the possibility of collecting permeate from block (Y) in a container until its conductivity reaches a value in the range of 20-600 μS / cm, preferably 40-600 μS / cm, and then feeding the permeate for desorption into block (a).

[0084] In another embodiment, to solve the stated problem and achieve the technical result, a plant for producing lithium carbonate from a lithium-containing solution is proposed, including:

[0085] (a) a unit for sorption and desorption of a lithium-containing solution, configured to remove the eluate;

[0086] (b) a unit for obtaining a concentrate purified from impurities from the eluate; wherein the unit (b) includes (N) a unit for reverse osmosis concentration of the eluate to obtain a concentrate and a permeate, characterized in that the installation is configured to collect the permeate from the unit (N) in a container until the concentration of lithium salts in it is in the range of 0.01-50 mg / l in terms of elemental lithium. and Preferably, the installation is configured to collect the permeate from the unit (N) in a container until the concentration of lithium salts in it is in the range of 0.1-50 mg / l in terms of elemental lithium, preferably 10-50 mg / l in terms of elemental lithium, and then feeding the permeate for desorption to the unit (a).

[0087] Preferably, the installation is configured to control the electrical conductivity of the concentrate obtained in the block (Y).

[0088] Preferably, the installation contains:

[0089] (c) a concentrate precipitation unit configured to separate the precipitate and the mother liquor; wherein the installation is configured to feed the mother liquor from unit (c) for mixing with the lithium-containing solution fed to unit (a).

[0090] Preferably, the installation is configured to regulate the pH of the mother liquor from block (c) before feeding it for mixing with the lithium-containing solution fed to block (a).

[0091] Preferably, in block (c) the separation of the precipitate and the mother liquor is carried out in a centrifuge.

[0092] Preferably, block (a) comprises a column with a sorbent based on a chlorine-containing variety of double aluminum and lithium hydroxide.

[0093] Preferably, the block (Ь) includes (Ь2) a block for cleaning the concentrate from impurities.

[0094] Preferably, the block (Ь2) includes a unit for evaporating the concentrate before cleaning it from impurities, wherein the evaporation unit is designed with the possibility of feeding the distillate obtained during evaporation to a unit for preparing reagents used in the block (Ь2) and / or the block (c).

[0095] Preferably, the block (Ь2) is configured to separate from the concentrate a precipitate containing impurities, to obtain a solution containing said precipitate, to regulate the pH of said solution, and to feed this solution for mixing with a lithium-containing solution fed to the block (a).

[0096] Preferably, the block (Ь) includes (ЬГ) a block for purifying the eluate from impurities.

[0097] Preferably, the installation includes a unit (Ь2) for purifying the concentrate from impurities, containing a unit for evaporating the concentrate before purifying it from impurities, wherein the evaporation unit is designed with the possibility of feeding the distillate obtained during evaporation to a unit for preparing reagents used in unit (ЬГ) and / or unit (Ы) and / or unit (с).

[0098] Preferably, the block (ЬГ) is configured to separate from the eluate a precipitate containing impurities, to obtain a solution containing said precipitate, to regulate the pH of said solution, and to feed this solution for mixing with a lithium-containing solution fed to the block (a).

[0099] Preferably, the block (ЬГ) is configured to separate from the eluate a precipitate containing impurities and to obtain a solution containing said precipitate, wherein the block (Ь2) is configured to separate from the concentrate a precipitate containing impurities and to obtain a solution containing said precipitate, wherein the installation comprises a block configured to mix said solutions to obtain a mixed solution, to regulate the pH of the mixed solution, and to feed this mixed solution for mixing with a lithium-containing solution fed to the block (a).

[0100] All the advantages of the claimed installation are similar to the advantages of the claimed method, indicated above, and all statements regarding the claimed method are fully applicable to the claimed installation.

[0101] Brief description of the drawings

[0102] The drawings are provided to provide a better understanding of the invention, but it will be obvious to those skilled in the art that the disclosed invention is not limited to the embodiment shown therein. Fig. 1 shows a block diagram of the first (best) embodiment of the invention.

[0103] Fig. 2-4 show a block diagram of a second embodiment of the invention.

[0104] Embodiments of the invention. The best embodiment of the invention.

[0105] The described embodiments are provided for illustrative purposes only. Those skilled in the art will readily recognize that other embodiments are possible without changing the essence of the invention.

[0106] Fig. 1 shows a block diagram of the best embodiment of the invention, Figs. 2-4 show block diagrams of a second embodiment of the invention.

[0107] The plant for producing lithium carbonate from a lithium-containing solution contains the following interconnected units and lines:

[0108] 1 - hydromineral raw material supply line (lithium-containing solution)

[0109] 2 - a container with hydromineral raw materials (lithium-containing solution) prepared for the sorption process

[0110] 2a - line for feeding hydromineral raw materials to sorption block 3

[0111] 3 - sorption block

[0112] Za - eluate discharge line

[0113] ЗЬ - raffinate discharge line

[0114] 4 - reverse osmosis unit

[0115] 4a - concentrate discharge line

[0116] 4Ь - permeate discharge line

[0117] 5 - evaporation block

[0118] 5a - evaporation concentrate discharge line

[0119] 5Ь - distillate outlet line

[0120] 6-1 - block for removing Ca, Mg from the eluate

[0121] 6a - purified eluate discharge line

[0122] 6Ь - line for removing sediment separated from the eluate -2 - unit for removing Ca, Mg from concentrate c - line for removing purified concentrate d - line for removing sediment separated from concentrate - technical lithium carbonate precipitation unit a - line for removing sediment Ь - line for removing mother liquor c - line for removing washing solution (washing solution) - carbonation unit a - line for removing - ion exchange unit a - line for removing 0 - decarbonation unit 0a - line for removing lithium carbonate 1 - unit for preparing reagents 1a - line for feeding sodium hydroxide solution 1b - line for feeding sodium carbonate 2 - unit for neutralizing mother liquor 2a - line for removing neutralized mother liquor 3 - unit for neutralizing Ca, Mg sediment 3a - line for removing solution containing sediment 4 - tank for liquid fed to desorption 4a - liquid drain line,5 - demineralized water feed line 6a - hydrochloric acid feed line 6b - hydrochloric acid feed line The functional units themselves are known from the prior art and are therefore described in general terms. The present invention consists of implementing such a sequence of actions using known units that leads to an increase in the efficiency of the lithium production process, unexpected and not anticipated in the prior art.

[0123] The installation works and the method is as follows

[0124] Stage (a) of sorption and desorption of lithium-containing solution

[0125] Hydromineral raw material (lithium-containing solution) is fed to the installation for obtaining lithium carbonate from a lithium-containing solution, which is fed through line 1 into tank 2 for preliminary processing of the hydromineral raw material.

[0126] Then the hydromineral raw material is fed through line 2a to sorption block 3, which contains columns filled with a sorbent based on a chlorine-containing variety of double aluminum and lithium hydroxide - AXIONIT Li-sorb for lithium sorption (DGAL-C1 (LiCl 2Al(OH)3 shH2O).

[0127] After completing the sorption and desorption cycles, the eluate is removed from sorption block 3 along line 3a, and the raffinate is removed along line 3b.

[0128] Eluate is a solution obtained during the desorption process of the extracted component (lithium).

[0129] Raffinate is a solution obtained during the process of sorption of the extracted component (lithium).

[0130] Stage (b) of obtaining a concentrate purified from impurities from the eluate can be carried out in two ways.

[0131] Option 1 (best)

[0132] Stage (Ы) of reverse osmosis concentration of eluate

[0133] Through line Za, the eluate is fed into block 4 of the reverse osmosis system, which is designed for reverse osmosis concentration of the eluate.

[0134] From block 4 of the reverse osmosis, concentrate is removed through line 4a and permeate is removed through line 4b.

[0135] Stage (Ь2) of purification of concentrate from impurities Concentrate is fed through line 4a to evaporation block 5.

[0136] From the evaporation block 5, the evaporation concentrate is removed through line 5a, and the distillate is removed through line 5b.

[0137] The evaporation concentrate is fed through line 5a to block 6-2 for removing Ca and Mg from the concentrate, where the concentrate is purified from calcium and magnesium.

[0138] From block 6-2 for removing Ca and Mg, the filtrate, which is a lithium-containing concentrate purified from calcium and magnesium, is removed through line 6c, and the sediment is removed (unloaded) through line 6d.

[0139] Option 2

[0140] Stage (ЬГ) of purification of eluate from impurities

[0141] Through line Za, the eluate is fed to block 6-1 for removing impurities, which is designed to purify the eluate from impurities such as Ca and Mg.

[0142] From block 6-1, the eluate, purified from impurities, is removed through line 6a, and the sediment is removed (unloaded) through line 6b.

[0143] Stage (Ы) of reverse osmosis concentration of eluate

[0144] Purified eluate is fed through line 6a to reverse osmosis unit 4.

[0145] From block 4 of the reverse osmosis, concentrate is removed through line 4a and permeate is removed through line 4b.

[0146] Concentrate is fed through line 4a to evaporation block 5.

[0147] From the evaporation block 5, the evaporation concentrate is removed through line 5a, and the distillate is removed through line 5b.

[0148] Stage (Ь2) of purification of concentrate from impurities

[0149] Through line 5a, the concentrate is fed to block 6-2 for removing impurities, which is designed to purify the concentrate from impurities such as Ca and Mg.

[0150] From block 6-2 for removing Ca and Mg, the filtrate, which is a lithium-containing concentrate purified from calcium and magnesium, is removed through line 6c, and the sediment is removed (unloaded) through line 6d.

[0151] Stage (c) of precipitation of concentrate after stage (b) with the production of precipitate and mother liquor, and separation of precipitate and mother liquor. Through line 6c, purified concentrate is fed to block 7 for precipitation of technical lithium carbonate.

[0152] From block 7 for precipitation of technical lithium carbonate, the precipitate is removed through line 7a, the mother liquor is removed through line 7b, and the wash solution is removed through line 7c.

[0153] The sediment is fed through line 7a to the carbonation unit 8, from which it is fed through line 8a to the ion exchange unit 9, from which it is fed through line 9a to the decarbonation unit 10.

[0154] Battery-grade lithium carbonate is discharged from decarbonization unit 10 through line 10a.

[0155] To increase the efficiency of the process of obtaining lithium carbonate from lithium-containing solutions, the following additional operations are carried out.

[0156] The specified operations can be used individually to achieve the technical result; in preferred embodiments, they are used in any combination, which allows for the stated technical result to be achieved more effectively; in the most preferred embodiment, they are used all together to achieve the highest results.

[0157] 1. Feeding permeate from reverse osmosis unit 4 for desorption into sorption unit 3.

[0158] In block 4 of the reverse osmosis, the eluate supplied through line 3a is directed using a centrifugal pump through a bag filter with a pore size of no more than 5 microns to sequentially located reverse osmosis membranes, the pressure during the process is 20-60 bar.

[0159] The result is permeate and concentrate flows.

[0160] Next, in block 4 of reverse osmosis, the concentrate obtained from the previous stages of osmosis is fed by a pump to the reverse osmosis membrane with a maximum pressure of one / several of the stages of 60-150 bar, preferably 80-120, most preferably 100-120 bar.

[0161] The reverse osmosis unit continues to operate until the concentrate reaches a conductivity of 16,000-60,000 µS / cm. Permeate (filtrate) is the flow of substance passing through a semipermeable membrane during membrane separation. Concentrate is a solution with a lithium concentration higher than the lithium concentration in the solution at the previous stage of the process.

[0162] The resulting permeate is removed along line 4b and collected in container 14 until a specified range of electrical conductivity of the collected permeate is reached, monitoring the conductivity in the range of 10-600 μS / cm, preferably 20-600 μS / cm, most preferably 40-600 μS / cm, using conductometer readings.

[0163] The above conductivity is ensured by the presence of lithium salts in the range of 0.01-50 mg / L lithium, preferably 0.1-50 mg / L, most preferably 10-50 mg / L, which are controlled by methods of analyzing samples using inductively coupled plasma spectrometry, or other methods of analytical research that allow analysis of the elemental composition.

[0164] After reaching the specified range of electrical conductivity of the collected permeate, it is sent via line 14a to sorption unit 3 for desorption of columns filled with AXIONIT Li-sorb sorbent, which allows for an increase in the service life of the sorbent, as well as an increase in the degree of lithium extraction and a reduction in water consumption in the process.

[0165] 2. Feeding a solution of neutralized sediment from block 6 for removing Ca, Mg for mixing with the initial hydromineral raw material

[0166] Option 1 (best)

[0167] As shown in Fig. 1, line 4a feeds the concentrate to evaporation unit 5, where it is evaporated. Evaporation may be omitted, but it can further improve the efficiency of the process.

[0168] From the evaporation block 5, the evaporation concentrate is removed via line 5a, and the distillate is removed via line 5b to the reagent preparation block 11, which allows for an additional reduction in water consumption.

[0169] The evaporation concentrate is fed through line 5a to block 6-2 for removing Ca and Mg.

[0170] The concentrate fed through line 5a is purified from calcium and magnesium in block 6-2 for Ca and Mg removal, which contains an interconnected precipitation reactor, centrifuge, Nutsche filter, pipes, and pumps (not shown). The evaporation concentrate (obtained after evaporation), fed through line 5a, is pumped into the reactor, and mixing is started.

[0171] While mixing, a sodium hydroxide solution is introduced from reagent preparation unit 11 through line 11a using a pump until a pH value of (10.75±0.25) units is reached to remove magnesium from the solution.

[0172] When mixing sodium hydroxide solution with the concentrate, a gel-like precipitate of magnesium hydroxide is formed.

[0173] Next, the calculated amount of sodium carbonate is added to the reactor (the maximum permissible excess of sodium carbonate is no more than 10%) and the resulting pulp is mixed for 15 minutes.

[0174] After mixing is complete, the pulp is discharged from the sedimentation reactor into a centrifuge and centrifuged for 30 minutes at 300 rpm, 20 minutes at 450 rpm, 10 minutes at 600 rpm, and 10 minutes at 900 rpm.

[0175] Instead of a centrifuge, you can use: press filters, Nutsche filters, a combination of a thickener with a centrifuge / press filter / Nutsche filter, and so on.

[0176] The centrifuge-obtained effluent flows by gravity into a drainage pump, from where it is then fed to a Nutsche filter.

[0177] After centrifugation is complete, 2 liters of distilled water are poured into the centrifuge and the sediment is washed; the washing water is also sent to the Nutsche filter.

[0178] The solution is filtered using a Nutsche filter and sent to a filtrate receiver-collector, from where it is then transferred to a storage tank using a pump.

[0179] The resulting filtrate, which is a lithium-containing concentrate purified from calcium and magnesium, is discharged through line 6c.

[0180] The precipitate obtained after centrifugation and filtration is discharged via line 6d into the Ca, Mg precipitate neutralization unit 13, and hydrochloric acid is added via line 16a so that the pH of the solution is 1-3, preferably 1.01-2, most preferably 1.01-1.3.

[0181] After the sediment has completely dissolved, the resulting solution is fed through line 13a for mixing with the initial hydromineral raw material in tank 2 for mixing the flows, which allows for an increase in the through extraction rate of lithium, as well as the elimination of solid production waste.

[0182] Option 2

[0183] In block 6-1 for removing Ca and Mg, the eluate is purified from calcium and magnesium in the same way as for the concentrate in option 1.

[0184] In block 6-2 for removing Ca and Mg, the concentrate is purified from calcium and magnesium in the same way as for the concentrate in option 1.

[0185] In one variant (a), shown in Fig. 2, the sediment removed from block 6-1 via line 6b, containing impurities from the purification of the eluate, is discharged into block 13 for neutralizing the Ca, Mg sediment and hydrochloric acid is added via line 16a so that the pH of the solution is 1-3, preferably 1.01-2, most preferably 1.01-1.3.

[0186] After the sediment has completely dissolved, the resulting solution is fed through line 13a for mixing with the initial hydromineral raw material in tank 2 for mixing the flows, which allows for an increase in the through extraction rate of lithium, as well as the elimination of solid production waste.

[0187] In another variant (b), shown in Fig. 4, the sediment removed from block 6-2 via line 6d, containing impurities from the purification of the concentrate, is discharged into block 13 for neutralizing the sediment Ca, Mg and hydrochloric acid is added via line 16a so that the pH of the solution is 1-3, preferably 1.01-2, most preferably 1.01-1.3.

[0188] After the sediment has completely dissolved, the resulting solution is fed through line 13a for mixing with the initial hydromineral raw material in tank 2 for mixing the flows, which allows for an increase in the through extraction rate of lithium, as well as the elimination of solid production waste.

[0189] In the preferred embodiment (c), shown in Fig. 3, the sediment removed from block 6-1 via line 6b, containing impurities from the purification of the eluate, as well as the sediment removed from block 6-2 via line 6d, containing impurities from the purification of the concentrate, are discharged into block 13 for neutralizing the Ca, Mg sediment.

[0190] Hydrochloric acid is added to block 13 via line 16a while stirring to obtain a mixed solution, wherein hydrochloric acid is added so that the pH of the mixed solution is 1-3, preferably 1.01-2, most preferably 1.01-1.3. After the precipitate has completely dissolved, the resulting mixed solution is fed via line 13a for mixing with the initial hydromineral raw material in tank 2 for mixing the flows, which makes it possible to increase the through extraction rate of lithium, as well as to eliminate solid production waste.

[0191] 3. Feeding neutralized mother liquor from block 7 for precipitation of technical lithium carbonate for mixing with the initial hydromineral raw material

[0192] Through line 6c, the lithium-containing concentrate purified from calcium and magnesium is fed into block 7 for precipitation of technical lithium carbonate, which includes a reactor and a centrifuge connected to each other.

[0193] To obtain lithium carbonate (technical), the concentrate purified from calcium and magnesium is treated with a solution of sodium carbonate.

[0194] The precipitation process proceeds according to the reaction:

[0195] 2LiCl + Na2CO3= Li2CO3+ 2NaCl.

[0196] The precipitation of lithium carbonate (technical) is carried out in a reactor that is part of block 7 for the precipitation of technical lithium carbonate.

[0197] In the reactor of the reagent preparation block 11, a sodium carbonate solution is prepared and fed through line 11b to the lithium carbonate precipitation reactor of the technical lithium carbonate precipitation block 7.

[0198] Through line 6a, lithium-containing concentrate purified from calcium and magnesium is fed into the reactor using a pump, the solution is heated to 75°-95°, preferably 80°-95°, most preferably 85°-95°, and maintained with stirring for 20-60 minutes, preferably 30-50 minutes, most preferably 30-40 minutes, resulting in a hot pulp.

[0199] The hot pulp is then discharged into a centrifuge, where it is separated into sediment and mother liquor. Alternatively, other filtering equipment known from the prior art can be used.

[0200] The mother liquor is collected and discharged via line 7b into the mother liquor neutralization unit 12, where it is acidified to a pH of 1.01-3, preferably to 1.3-2.5, more preferably to 1.4-2.0, most preferably to 1.9 with hydrochloric acid supplied via line 16b. The resulting mother liquor is supplied via line 12a for mixing with the initial hydromineral raw material in tank 2 for mixing flows, which makes it possible to increase the degree of lithium extraction in the process.

[0201] The precipitate, which is wet technical lithium carbonate, is filtered from the technical lithium carbonate precipitation unit 7, washed, and discharged through line 7a.

[0202] Through line 7a, the sediment is fed to the carbonation unit 8, the ion exchange unit 9 and the decarbonation unit 10 for additional removal of Na, K, Ca, Mg, and B from the commercial product.

[0203] Battery-grade lithium carbonate is discharged from decarbonization unit 10 through line 10a.

[0204] The test results of the declared method and installation are presented in Tables 1 and 2 below.

[0205] Table 1

[0206]

[0207] Table 2

[0208]

[0209] Thus, the claimed invention provided:

[0210] - increasing the efficiency of the lithium production process,

[0211] - high extraction of lithium from lithium-containing solutions, including from solid waste from the lithium extraction process,

[0212] - production of battery grade lithium carbonate,

[0213] - increasing the effective operating life of the sorbent (increasing the service life of the sorbent),

[0214] - absence of solid production waste in the form of calcium and magnesium salts,

[0215] - reduction of water and energy consumption of the technology.

Claims

Invention formula 1. A method for producing lithium carbonate from a lithium-containing solution, comprising the following steps: (a) sorption and desorption of a lithium-containing solution to obtain an eluate; (b) obtaining a concentrate from the eluate purified from impurities; wherein step (b) includes a step (Y) of reverse osmosis concentration of the eluate to obtain a concentrate and permeate; characterized in that the permeate from step (Y) is collected in a container until its conductivity reaches a value in the range of 10-600 μS / cm, and then the permeate is sent for desorption at step (a).

2. The method according to I. 1, characterized in that the permeate from stage (Y) is collected in a container until its conductivity reaches a value in the range of 20-600 μS / cm, preferably 40-600 μS / cm, and then the permeate is sent for desorption at stage (a).

3. A method for producing lithium carbonate from a lithium-containing solution, comprising the following steps: (a) sorption and desorption of a lithium-containing solution to obtain an eluate; (b) obtaining from the eluate a concentrate purified from impurities; wherein step (b) includes step (Y) of reverse osmosis concentration of the eluate to obtain a concentrate and permeate; characterized in that the permeate from step (Y) is collected in a container until the concentration of lithium salts in it reaches a range of 0.01-50 mg / l in terms of elemental lithium, and then the permeate is sent for desorption at step (a).

4. The method according to item 3, characterized in that the permeate from stage (Y) is collected in a container until the concentration of lithium salts in it reaches a range of 0.1-50 mg / l in terms of elemental lithium, preferably 10-50 mg / l in terms of elemental lithium, and then the permeate is sent for desorption at stage (a).

5. The method according to paragraph 1 or 3, characterized in that at stage (Y) a concentrate is obtained having an electrical conductivity value of 16,000-60,000 μS / cm.

6. The method according to item 1 or item 3, characterized in that after step (b), step (c) of precipitating the concentrate to obtain a precipitate and a mother liquor, and separating the precipitate and the mother liquor is carried out; wherein the mother liquor from step (c) is fed for mixing with the lithium-containing solution before being fed to step (a).

7. The method according to item 6, characterized in that before feeding the mother liquor from step (c) for mixing with the lithium-containing solution, the pH value of the mother liquor is brought to 1.01-3, preferably to 1.3-2.5, more preferably to 1.4-2.0, most preferably to 1.

9.

8. The method according to item 7, characterized in that the pH of the mother liquor from step (c) is adjusted to the specified value by adding hydrochloric acid.

9. The method according to claim 6, characterized in that in step (c) the precipitation of the concentrate is carried out in a reactor, wherein the concentrate is heated to 75°-95°, preferably to 80°-95°, most preferably to 85°-95°, and maintained under stirring for 20-60 minutes, preferably 30-50 minutes, most preferably 30-40 minutes.

10. The method according to item 6, characterized in that at stage (c) the separation of the sediment and the mother liquor is carried out in a centrifuge.

11. The method according to item 1 or item 3, characterized in that at stage (a) a sorbent based on a chlorine-containing variety of double aluminum and lithium hydroxide is used.

12. The method according to item 1 or item 3, characterized in that stage (b) after stage (Y) includes stage (b2) of purifying the concentrate from impurities.

13. The method according to item 12, characterized in that after stage (Ы) and before stage (Ь2), the concentrate is evaporated, and the distillate obtained during evaporation is used to prepare the reagents used in stage (с) and / or stage (Ь2).

14. The method according to item 12, characterized in that at step (Ь2) the precipitate containing impurities is separated from the concentrate and a solution containing the said precipitate is obtained, wherein the pH value of said solution is brought to 1-3, preferably 1.01-2, most preferably 1.01-1.3, and this solution is fed for mixing with the lithium-containing solution before feeding it to step (a).

15. The method according to item 14, characterized in that at step (b2), before separating the precipitate containing impurities from the concentrate, a sodium hydroxide solution is added to the concentrate until a pH value in the range of 10-12 is reached, and sodium carbonate is also added and mixed.

16. The method according to item 15, characterized in that the pH of the solution obtained by dissolving the precipitate in step (b2) is brought to the specified value by adding hydrochloric acid.

17. The method according to item 12, characterized in that stage (b) before stage (Y) includes stage (bG) of purifying the eluate from impurities.

18. The method according to item 17, characterized in that at step (bG) a precipitate containing impurities is separated from the eluate and a solution containing said precipitate is obtained, wherein the pH value of said solution is brought to 1-3, preferably 1.01-2, most preferably 1.01-1.3, and this solution is fed for mixing with a lithium-containing solution before it is fed to step (a).

19. The method according to item 18, characterized in that at step (ЬГ), before separating the precipitate containing impurities from the eluate, a sodium hydroxide solution is added to the eluate until a pH value in the range of 10-12 is reached, and sodium carbonate is also added and mixed.

20. The method according to item 17, characterized in that at step (bG) a precipitate containing impurities is separated from the eluate, while at step (b2) a precipitate containing impurities is separated from the concentrate, wherein said precipitates are dissolved to obtain a mixed solution, the pH of which is adjusted to 1-3, preferably 1.01-2, most preferably 1.01-1.3, and this mixed solution is fed for mixing with the lithium-containing solution before feeding it to step (a).

21. The method according to item 20, characterized in that at stage (ЬГ) before separating the precipitate containing impurities from the eluate, a sodium hydroxide solution is added to the eluate until reaching a pH in the range of 10-12, and also add sodium carbonate and mix, while at step (Ь2) before separating the precipitate containing impurities from the concentrate, a sodium hydroxide solution is added to the concentrate until reaching a pH in the range of 10-12, and also add sodium carbonate and mix.

22. The method according to item 17, characterized in that after stage (Ы) and before stage (Ь2), the concentrate is evaporated, and the distillate obtained during evaporation is used to prepare the reagents used in stage (c) and / or stage (ЬГ) and / or stage (Ь2).

23. The method according to item 18 or item 20, characterized in that the pH of the solution obtained by dissolving the precipitate is brought to the specified value by adding hydrochloric acid.

24. An installation for producing lithium carbonate from a lithium-containing solution, comprising: (a) a unit for sorption and desorption of a lithium-containing solution, configured to remove the eluate; (b) a unit for obtaining from the eluate a concentrate purified from impurities; wherein the unit (b) includes (N) a unit for reverse osmosis concentration of the eluate with the production of a concentrate and permeate, characterized in that the installation is designed with the possibility of collecting the permeate from the unit (N) in a container until its conductivity reaches a value in the range of 10-600 μS / cm.

25. The installation according to item 24, characterized in that the installation is designed with the possibility of collecting permeate from the block (Y) in a container until its conductivity reaches a value in the range of 20-600 μS / cm, preferably 40-600 μS / cm, and then feeding the permeate for desorption into the block (a).

26. An installation for producing lithium carbonate from a lithium-containing solution, comprising: (a) a unit for sorption and desorption of a lithium-containing solution, designed with the possibility of removing the eluate; (b) a unit for obtaining from the eluate a concentrate purified from impurities; wherein the unit (b) includes (N) a unit for reverse osmosis concentration of the eluate with the production of a concentrate and permeate, characterized in that the installation is designed with the possibility of collecting the permeate from the unit (N) in a container until the concentration of lithium salts in it reaches a range of 0.01-50 mg / l in terms of elemental lithium.

27. The installation according to item 26, characterized in that the installation is designed with the possibility of collecting permeate from the block (Y) in a container until the concentration of lithium salts in it reaches a range of 0.1-50 mg / l in terms of elemental lithium, preferably 10-50 mg / l in terms of elemental lithium, and then feeding the permeate for desorption into the block (a).

28. The installation according to item 24 or item 26, characterized in that the installation is designed with the possibility of monitoring the electrical conductivity of the concentrate obtained in the block (Ы).

29. The plant according to paragraph 24 or paragraph 26, characterized in that the plant comprises (c) a concentrate precipitation unit, configured to separate the precipitate and the mother liquor; wherein the plant is configured to feed the mother liquor from the unit (c) for mixing with the lithium-containing solution fed to the unit (a).

30. The installation according to paragraph 29, characterized in that the installation is designed with the possibility of regulating the pH of the mother liquor from block (c) before feeding it for mixing with the lithium-containing solution fed to block (a).

31. The installation according to paragraph 29, characterized in that in block (c) the separation of the sediment and the mother liquor is carried out in a centrifuge.

32. The installation according to paragraph 24 or paragraph 26, characterized in that the block (a) contains a column with a sorbent based on a chlorine-containing variety of double aluminum and lithium hydroxide.

33. The installation according to paragraph 24 or paragraph 26, characterized in that the block (Ь) includes (Ь2) a block for cleaning the concentrate from impurities.

34. The installation according to paragraph 33, characterized in that the block (Ь2) includes a unit for evaporating the concentrate before cleaning it from impurities, and the evaporation unit is designed with the possibility of feeding the distillate obtained during evaporation into a unit for preparing the reagents used in the block (Ь2) and / or block (c).

35. The installation according to item 33, characterized in that the block (Ь2) is designed with the possibility of separating the precipitate containing impurities from the concentrate, obtaining a solution containing said precipitate, regulating the pH of said solution, and feeding this solution for mixing with the lithium-containing solution fed to the block (a).

36. The installation according to item 33, characterized in that the block (Ь) includes (ЬГ) a block for cleaning the eluate from impurities.

37. The installation according to item 36, characterized in that the block (Ь2) includes a unit for evaporating the concentrate before cleaning it from impurities, containing a unit for evaporating the concentrate before cleaning it from impurities, wherein the evaporation unit is designed with the possibility of feeding the distillate obtained during evaporation to a unit for preparing the reagents used in the block (ЬГ) and / or the block (Ы) and / or the block (с).

38. The installation according to item 36, characterized in that the block (ЬГ) is designed with the possibility of separating from the eluate a precipitate containing impurities, obtaining a solution containing said precipitate, regulating the pH of said solution, and feeding this solution for mixing with a lithium-containing solution fed to the block (a).

39. The installation according to item 36, characterized in that the block (ЬГ) is designed with the possibility of separating the precipitate containing impurities from the eluate and obtaining a solution containing the said precipitate, wherein the block (Ь2) is configured to separate the precipitate containing impurities from the concentrate, to obtain a solution containing said precipitate, and the installation comprises a block configured to mix said solutions to obtain a mixed solution, to regulate the pH of the mixed solution, and to feed this mixed solution for mixing with the lithium-containing solution fed to the block (a).

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