JP2019099901A - Method for recovering lithium from lithium-containing solution - Google Patents

Abstract

To provide a method for effectively recovering lithium as a lithium salt or lithium carbonate from lithium in a lithium-containing solution.SOLUTION: There is provided a method for recovering lithium from a lithium-containing solution, including 1. a process for adding phosphoric acid or phosphate to a solution including lithium and solidifying the lithium as lithium phosphate, 2. a process for separating solidified lithium phosphate, 3. a process for adding the solidified lithium phosphate to water or solution containing an adsorbent of lithium and developing them to adsorb a lithium component of the lithium phosphate to the adsorbent, 4. a process for separating the adsorbent which adsorbs the lithium, and 5. a process for detaching the adsorbed lithium to make a concentrated aqueous solution.SELECTED DRAWING: None

Description

The present invention relates to a lithium-containing aqueous solution generated from waste water from lithium-containing ore, lithium-containing brine, seawater, underground water, and waste recycling processes of lithium-containing products including lithium ion batteries. Recovery method for efficiently recovering lithium from

Lithium metal and its compounds have been conventionally used for pharmaceuticals, refrigerants, lubricating oils, alloy components such as aluminum, glass and ceramics, etc., but in recent years batteries such as lithium ion batteries, especially secondary batteries The demand for batteries is rapidly increasing, and the possibility of a tight supply of lithium has become a problem in the future.

In other words, lithium production is currently produced by evaporation from salt lake brine (lithium concentration 0.05 to 0.2%), and lithium-containing ores such as spodumene, ambrigonite, petalite, and levitrite (lithium content 2 to 6%) are roughly divided into two types of production by leaching with sulfuric acid or lime, but with the recent increase in demand, lithium contained in trace amounts in seawater (0.17 ppm) and geothermal water, Attempts have been made to extract and produce using a special adsorbent that selectively adsorbs lithium synthesized from manganese oxide, ceramic and the like.

In addition, after combining used batteries with dismantling, crushing, sorting, and baking processes as appropriate, recovery of lithium by methods such as final leaching with acid etc. has also started to be conducted, and in the future such Production by recycling of lithium is expected to increase.

In these lithium recovery processes, lithium carbonate is precipitated by adding carbon dioxide gas or an alkali metal carbonate to a lithium-containing aqueous solution after finally leaching lithium into water. For example, sodium carbonate is added to an aqueous solution of lithium chloride, precipitated as lithium carbonate, and separated from an aqueous solution of sodium chloride to recover lithium as lithium carbonate. Alternatively, a method of recovering as an aqueous solution of lithium hydroxide is performed by adding an alkaline earth metal hydroxide. For example, lithium hydroxide is separated and recovered by adding calcium hydroxide to an aqueous solution of lithium sulfate to form an aqueous solution of lithium hydroxide, and separating the precipitate of calcium sulfate formed simultaneously.

At this time, since lithium compounds are both slightly soluble in the formation of lithium carbonate or lithium hydroxide, the higher the concentration of lithium in the lithium-containing aqueous solution, the higher the reaction efficiency and the better the recovery rate. Because it is economically advantageous, how to concentrate the lithium-containing aqueous solution after lithium leaching is a major issue.

Patent Document 1 discloses a process for recovering lithium from a lithium ion waste battery, after dissolving with an acid, separating and recovering metal components other than lithium, and repeating lithium solvent extraction / back extraction to recover lithium. Although it is shown, the operation itself is very complicated, and solvent extraction / back extraction is repeated only for lithium, and a very complicated process such as pH control is performed between them. Naturally, the concentration may be lowered more than necessary during the process, and impurities may be involved, etc., so that the operation is complicated and the yield may be greatly reduced.

Patent Document 2 shows that lithium is adsorbed and desorbed from a dilute lithium solution by a lithium adsorbent, and electrodialysis is repeated to concentrate and recover lithium, but the operation is extremely complicated and cost-effective. There is also concern that it will be very expensive.

In Patent Document 3, a manganese oxide capable of selectively adsorbing lithium is synthesized, and lithium recovery from a low concentration lithium-containing aqueous solution is realized. Although it is necessary to carry out the adsorption with alkalinity, many impurity cations are precipitated as hydroxides with alkalinity, and there is a problem that concentration / separation from the liquid containing impurities can not be performed, and the application range is very limited. There is a problem of

On the other hand, in Patent Document 4, a phosphoric acid compound is added to a lithium-containing aqueous solution to precipitate lithium phosphate, which is separated and recovered by solid-liquid separation to concentrate lithium by a pure chemical method. . However, lithium phosphate recovered as solid content needs to be mixed with the metal compound again in the acidic solution to leach out lithium in the solution, and the method is shown, but the operation becomes complicated. There's a problem. Moreover, in this leaching step, since it mixes with other metal ions again, it may become difficult to obtain high purity products.

In Patent Document 5, a sparingly soluble lithium phosphate compound is prepared, which is used to re-dissolve phosphoric acid by adding other metal ions, and to precipitate it as lithium carbonate. The operation is very complicated since other metal ions always intervene. In addition, there is a problem that the conventional method is insufficient to maintain the purity of lithium.

In Non-Patent Document 1, after phosphoric acid is added to a lithium-containing aqueous solution to separate it as lithium phosphate, phosphoric acid is further added in excess and re-dissolved, and the re-dissolved solution is mixed with a cation exchange resin to make lithium The method of recovery is shown. Since the ion exchange resin floats in the column, it is an operation in a state in which lithium phosphate is completely dissolved under strong acidity, and there is a problem that the handling becomes complicated. Moreover, the ion exchange resin to be used also has to be strong acid compatible, and there is a problem that the dissolution conditions become complicated.

JP 2007-122885 A JP 2004-142986 A Unexamined-Japanese-Patent No. 2004-25113 JP, 2011-168461, A Japanese Patent Application Publication No. 2015-515440

CREATIVE 10, No 2. 2002

The present invention relates to lithium in a lithium-containing aqueous solution, from a solid lithium phosphate formed by the addition of phosphoric acid or a phosphate, in a method which is easy to operate and minimizes residuals of other metal elements etc. It was an object of the present invention to provide a method for efficiently recovering lithium as a lithium salt or lithium carbonate by obtaining an aqueous solution.

In the present invention, first, an aqueous solution containing lithium, Adding phosphoric acid or phosphate to solidify the lithium as lithium phosphate; A step of separating solidified lithium phosphate; Adding the solidified lithium phosphate to water or an aqueous solution containing a lithium adsorbent, and developing the lithium phosphate to adsorb the lithium component of the lithium phosphate onto the adsorbent; 4. Separating the lithium-adsorbed adsorbent; A method for recovering lithium from a lithium-containing aqueous solution, comprising the step of desorbing adsorbed lithium from the adsorbent to obtain a concentrated hard aqueous solution of lithium, and secondly, an aqueous solution containing lithium; Adding phosphoric acid or phosphate to solidify the lithium as lithium phosphate; A step of separating solidified lithium phosphate; Developing the separated lithium phosphate in water to form a slurry; Then, a lithium adsorbent is added to the slurry to adsorb lithium, and Separating the lithium-adsorbed adsorbent; It is a method for recovering lithium from a lithium-containing aqueous solution, including the step of desorbing the adsorbed lithium from the adsorbent having the lithium adsorbed thereon to obtain a concentrated aqueous solution of lithium.

Details will be described below.
Lithium combines with phosphoric acid and precipitates as lithium phosphate. Applying this principle to the present invention, a relatively dilute aqueous solution containing lithium is mixed and reacted with a solution of phosphoric acid, sodium phosphate, potassium phosphate or the like to precipitate as lithium phosphate. The conditions at this time are not particularly specified, and the concentration and temperature for mixing are not particularly specified. However, it goes without saying that the higher concentration of phosphate solution is better. The phosphoric acid and phosphate to be used at this time are not particularly specified, but in consideration of subsequent separation and purification, alkali metal phosphate is desirable. That is, since alkali metal lithium salts other than lithium salts do not precipitate in an aqueous solution as phosphates or as other salts, only lithium can be separated as a solid of lithium phosphate.

With the addition of phosphoric acid and such phosphates, nearly 100% of the lithium ions precipitate as lithium phosphate. In addition, it is desirable that a slight excess of phosphoric acid and phosphate to be added be added so that lithium is sufficiently reacted. That is, although the excess amount is not particularly specified, it is desirable that it is 10 to 20% excess to the calculated value.

The lithium-containing aqueous solution, which is the material to be treated, is preferably alkaline with a pH of 10 or more, and if not alkaline, it is desirable to make the pH about 10 in advance with caustic soda or an aqueous caustic potash solution. At that time, precipitation of impurities may occur as a neutralization salt, but if such precipitation occurs, it is desirable to remove by filtration.

Next, as described above, a phosphoric acid or phosphate solution is mixed and reacted with a lithium-containing aqueous solution from which alkaline soluble impurities have been removed by alkaline neutralization precipitation, as described above. As a result, insoluble lithium phosphate is formed and precipitates, but the reaction solution containing the precipitate is reacted sufficiently by further stirring to grow lithium phosphate solid in the solution. The stirring time is not particularly specified, but is desirably maintained for about 30 minutes at the beaker level, and desirably determined experimentally at the industrial level according to the scale.

The precipitate that is formed and grown consists of lithium phosphate, which is filtered and fractionated. The conditions at this time are not particularly specified, but in the case of a small amount may be by ordinary suction filtration, and in the case of a large amount, a filter press filter may be used. The pore size of the filter paper or filter cloth used herein may be determined by the particle size of lithium phosphate to be produced, but in general, it is desirable to use a small filter cloth having a pore size of about 200 to 300 mesh. Naturally, the lithium phosphate filtered out here is washed with water. The product may be developed in pure water to form a slurry, but it may also be transferred to a lithium adsorption process which is solid as it is and is the next process.

In the case of preparing a suspension in which a lithium slurry is formed in advance, a solid adsorbent can be added to the slurry as it is. As a result, the adsorbent reacts with lithium, the lithium component is adsorbed to the solid adsorbent, and the phosphoric acid component dissolves in the liquid. As a matter of course, it is also possible to combine the adsorbent with the adsorbent suspended in water in advance, but in this case, it is necessary to take care so that the liquid amount does not increase more than necessary.

It is also possible to directly charge the lithium phosphate solid obtained in the above into a suspension in which the adsorbent is suspended, in which case lithium phosphate is produced while being dissolved in the suspension. The ions are adsorbed to the adsorbent, the slurry dissolves, and the phosphoric acid becomes a phosphoric acid solution. Here, the end of the reaction can be known by the absence of the presence of slurry solids. The same applies to the case where lithium phosphate solid is added to the aqueous solution containing the adsorbent, and water is previously added to lithium phosphate to form a slurry, and the adsorbent is added thereto.

The adsorbent to be used is not particularly specified, but there is one cation exchange resin of H type, which can almost completely adsorb lithium during adsorption, and is easily desorbed by acid it can. The cation exchange resin is not particularly specified, but is preferably a carboxylic acid type weak ion exchange resin. The weak ion exchange resin is characterized in that the subsequent release of lithium ions is facilitated, and the removal of lithium with a small amount of acid is possible, so that the subsequent process is facilitated.

Moreover, as cation exchange resin made into H type, it is easy to obtain, and stable strong acid type cation exchange resin can also be used preferably. In this case, it is characterized that lithium adsorption is very active, but instead, lithium must be made strongly acidic for lithium desorption, for example, lithium after desorption will be present in a strong acid. However, even in such a state, lithium can be precipitated as lithium carbonate if it is directly neutralized with sodium carbonate or potassium carbonate in a strong acid solution except a cation exchange resin.

When a strong acid type cation exchange resin is used, it is desirable to use hydrochloric acid (HCl) as an acid for lithium desorption. That is, when lithium is separated and taken out as lithium carbonate, only lithium carbonate can be taken out as a high purity precipitate because the solubility of sodium chloride and the like by-produced is sufficiently high. Needless to say, if lithium is kept at a high concentration in an acid, or lithium sulfate at a high concentration is considered as a product, desorption with sulfuric acid can be performed instead of with hydrochloric acid.

As a matter of course, the adsorbent does not have to be an ion exchange resin, and is not particularly designated as long as it can produce a high concentration solution of lithium by subsequent desorption, and for example, γ-MnO 2 is preferably used. However, special care should be taken as the handling may differ depending on the substance, and usually the handling may be complicated. For example, in the adsorption with .gamma.-MnO.sub.2, when desorption is carried out with an acid, the efficiency of desorption tends to be about 10% worse than that of the ion exchange resin. Depending on the application, care must be taken because the adsorbent for this inefficiency may remain in the recovered lithium as an impurity.

By separating from the adsorbent in this manner, a high concentration lithium aqueous solution can be obtained. Carbonate ions can be reacted with the high concentration lithium solution to precipitate and separate as lithium carbonate to recover lithium. The carbonate ion supply in this case may typically be sparged with CO2 gas, although this is less efficient, by the addition of alkali carbonates. Furthermore, CO 2 is reacted electrolytically with air (oxygen) to generate carbonate ion (CO 3-) and supply it.

When lithium ions are desorbed from the adsorbent with sulfuric acid, alkaline earth metal hydroxides are added by taking advantage of the fact that some alkaline earth metal sulfates have almost no solubility in water. It can also be precipitated as an alkaline earth metal sulfate to give lithium as a high concentration aqueous lithium hydroxide solution. Calcium hydroxide and barium hydroxide are good as the alkaline earth metal hydroxide, and the end point of the addition of the alkaline earth metal hydroxide is confirmed to be pH = 7 by strictly measuring the pH. It is obtained by The alkaline earth metal precipitates as sulfate and filtration gives a high concentration of lithium hydroxide.

According to the present invention, after making the dilute aqueous lithium solution alkaline by removing lithium from the waste lithium ion battery and removing the impurities, the impurities from the other can be obtained by relatively simple operation and chemical operation. It has become possible to recover as a highly concentrated lithium solution or pure lithium carbonate solid without any possibility of entering

As a lithium source in the present invention, lithium leachate obtained by leaching lithium with water, acid or alkali from waste of lithium-containing ore, brine, seawater, ground water, lithium ion battery such as lithium ion battery is used. The lithium content concentration at that time is preferably 300 mg / l to 128000 mg / l, and preferably 1000 mg / l or more. In addition, since there exists a tendency for phosphorylation to become inadequate when lithium concentration is 300 mg / l or less, it is unpreferable. Here, when the pH of the lithium leachate is higher than 10, the pH is adjusted to 10 or more, preferably 11 to 13 in advance by adding an alkali hydroxide when the pH is 10 or less. This is because when the pH is low, the solubility of lithium phosphate is increased at the time of phosphorylation in the next step, and the amount of lithium that can be recovered as a solid content decreases. In addition, if the pH is too high, there is a concern about the influence on the device materials. As a result, if any impurities are precipitated, the precipitate is removed by filtration or the like.

Phosphoric acid is added to the lithium solution and reacted with stirring to precipitate lithium phosphate. That is, under this condition, lithium phosphate precipitates as a precipitate because there is almost no solubility in water. Here, if the pH of the solution is lower than 10, the solubility of lithium phosphate is increased, and the recovery efficiency may be reduced accordingly, so the pH may be increased to more than 10 by adding an alkali hydroxide solution as necessary. Let's do it. The precipitate of lithium phosphate thus separated is separated by filtration.

The phosphoric acid to be added may be a phosphoric acid compound, such as trisodium phosphate, tripotassium phosphate, iron (III) phosphate and the like. The amount of phosphoric acid or phosphoric acid compound to be added here is desirably between its theoretical amount and its 20% excess, and in particular, 10 to 20% excess is desirable. Beyond that, the amount of phosphoric acid used is increased and there is no substantial effect. If the amount is smaller than the theoretical amount, lithium can not be captured sufficiently. The reaction with the phosphoric acid compound is desirably carried out at a temperature of 40 ° C to 90 ° C, preferably 50 ° C to 70 ° C. The reaction between the phosphoric acid or the phosphoric acid compound and lithium tends to improve the reaction efficiency as the temperature is higher, and lithium phosphate close to the theoretical amount can be obtained at 60 ° C. or higher.

The separated product of lithium phosphate is added to water containing a lithium adsorbent and stirred, and lithium phosphate is reacted with the lithium adsorbent to adsorb lithium to a solid adsorbent to separate phosphoric acid. The adsorbent is dissolved to form an aqueous phosphoric acid solution, and the solid adsorbent is separated by filtration. Here, the end point of the reaction can be easily found because the solid component is only the adsorbent and the rest is liquid. The amount of water containing the adsorbent is desirably such that the amount of lithium phosphate is present in the solution between 5 wt% and 50 wt%, preferably 10 wt% to 30 wt%.

As another method, the lithium phosphate separated material is suspended in pure water in advance to form a slurry, to which a lithium adsorbent is directly added and reacted to cause lithium to be adsorbed to the adsorbent. As a result, the insoluble lithium phosphate is changed to phosphoric acid and is dissolved in the solution. The adsorbent containing lithium is separated by filtration. Also in the preparation of the slurry in this case, it is desirable that the solid content in the liquid be 5 wt% to 50 wt%, preferably 10 wt% to 30 wt%.

The lithium adsorption material is, for example, an organic adsorbent such as strongly acidic ion exchange resin, weak acidic ion exchange resin, chelating resin, manganese oxide, titanium oxide, antimony oxide, niobium oxide, zirconium oxide, thorium arsenate, tin phosphate And inorganic adsorbents such as aluminum hydroxide, activated carbon, lithium-lanthanum-zirconate, smectite, zeolite, and zirconium phosphate. The inorganic adsorbent may be used in the form of powder or granulated using an organic or inorganic binder. These may be used alone or in the form of a mixture appropriately combined. When such lithium phosphate and lithium adsorbing material are mixed, lithium phosphate is in the form of a slurry, which is adsorbed by the adsorbent. After stirring for a predetermined time, solid-liquid separation is performed by a known method such as filtration or centrifugation, and the lithium-adsorbed material to which lithium is adsorbed and the filtrate containing phosphate ions are respectively recovered.

Thus, after lithium is adsorbed to the lithium adsorption material, it is separated into a liquid layer containing phosphate ions and a solid to which lithium is adsorbed by filtration. The phosphoric acid solution is used as it is or, if necessary, recovered as a metal salt and used for the next lithium treatment.

Next, lithium adsorbed from the lithium-adsorbed material adsorbed with lithium is recovered using a lithium eluent according to the lithium-adsorbed material used. As an eluent, an aqueous acid solution such as hydrochloric acid, dilute sulfuric acid or dilute nitric acid is used. In these aqueous acid solutions, the lithium adsorption material is dispersed and stirred to desorb lithium in the aqueous acid solution, or the lithium adsorption material is packed in a column or the like, and the aqueous acid solution flows through the column to introduce the aqueous acid solution. Lithium may be eluted. However, since the concentration of lithium in the eluent is determined by the amount of liquid at the time of lithium elution, it is necessary to determine the amount of liquid used as small as possible according to the solubility of the lithium salt to be obtained.

As an example, the case where lithium is eluted with a hydrochloric acid aqueous solution from a lithium-adsorbed strongly acidic cation exchange resin is shown above. That is, when lithium is adsorbed to a commercially available strong acid cation exchange resin (ion exchange capacity: 2.0 eq / l-R, apparent density 840 g / l-R), lithium adsorbed per 840 g of this ion exchange resin is Since it is 2 mol, 84.78 g of lithium chloride (formula weight 42.39) is present in the eluate when it is eluted with a hydrochloric acid aqueous solution. Since lithium chloride is dissolved in 100 ml of water at 25 ° C., 55 g is dissolved, and if there is a water amount of 154.15 ml, a saturated aqueous solution of lithium chloride can be obtained without precipitation. The amount of lithium adsorbed to the ion exchange resin is not necessarily required to satisfy the exchange capacity, and any amount of lithium may be adsorbed if it is within the exchange capacity. In addition, the concentration of the eluent does not necessarily have to be a saturated solution, and may be adjusted to any concentration as long as it does not interfere with the subsequent carbonation step or the step of forming a hydroxide.

The solution obtained here is obtained as a salt with the acid to be used at the time of desorption from the adsorbent, may be as it is, or may be heated and concentrated to obtain a salt solid as sulfate, chloride or nitrate. .

Further, as described above, lithium carbonate or lithium hydroxide may be used. That is, by adding carbonic acid or metal carbonate by a known method, it can be precipitated as lithium carbonate and separated and recovered as a carbonate as a solid. For example, when a calcium carbonate solution or an aqueous sodium carbonate solution is added to the obtained high concentration lithium salt solution, crystals of lithium carbonate are precipitated. Also, by bubbling CO 2 gas into the lithium salt aqueous solution obtained above, an excess of CO 2 gas is required, but lithium carbonate can be obtained as a solid. Alternatively, a lithium compound is obtained as a lithium hydroxide aqueous solution by desorbing a desorbing acid as a sulfuric acid in the form of lithium sulfate as sulfuric acid and neutralizing it with a hydroxide of an alkaline earth metal, that is, calcium hydroxide and / or barium hydroxide. Can.
Although details will be shown in the following examples, it goes without saying that the present invention is not limited to the scope of the examples.

As a simulated solution of the lithium recovery solution, 90.23 g of a reagent lithium sulfate monohydrate (manufactured by Kanto Chemical Co., Inc., Kaichi grade) was dissolved in pure water to make 500 ml. The lithium concentration of this lithium sulfate aqueous solution was 19574.8 ppm. In this material, 41.01 g of anhydrous trisodium phosphate (manufactured by Kishida Kagaku Co., Ltd., reagent first grade) was dissolved in water to make 500 ml. The concentration of this sodium phosphate aqueous solution was 0.5 mol / l. While stirring 50 ml of the lithium sulfate aqueous solution heated to 60 ° C., 96 ml of the sodium phosphate aqueous solution was slowly added. The pH was 11.6 after stirring for one hour after addition of the whole amount. The precipitate was separated by filtration using a quantitative filter paper (No. 5C manufactured by Toyo Roshi Co., Ltd.), and dried at 110 ° C. for 24 hours to obtain 5.62 g of granular lithium phosphate.

Pure water was added to the 19574.8 ppm lithium sulfate aqueous solution, and the trisodium phosphate aqueous solution was added by the same operation except that the lithium concentration was adjusted to 1957.5 ppm, 978.7 ppm and 489.4 ppm, respectively. The results of the case are shown in Table 1. From this, it was found that lithium phosphate can be precipitated and separated as a solid by the lithium liquid dilute solution and the phosphate.
The following shows the recovery as a high concentration lithium salt or lithium carbonate as a phosphate according to the present invention.

3.04 g of particulate lithium phosphate obtained in Example 1 was added to 100 ml of water and stirred to form a slurry. The pH of this slurry was 12.27. There are 0.8131 g of phosphorus and 0.5466 g of lithium in the slurry.
Next, while stirring the slurry, about 50 g of granular strong ion exchange resin (Amberlight IR120B manufactured by Organo Corporation) was added in a swollen state.
After stirring for about 5 minutes, the solid content in the slurry was dissolved, and when it became colorless and transparent, the ion exchange resin was separated and recovered by filtration. The filtrate after separation and recovery of the ion exchange resin had a pH of 1.62, and in the solution, 0.7140 g of P and 0.1620 g of lithium were present. On the other hand, the recovered ion exchange resin was immersed in a hydrochloric acid aqueous solution (1: 1), stirred for 5 minutes, and filtered. There were 0.0144 g of phosphorus and 0.3228 g of lithium in the filtrate. From the above results, it is found that the ion exchange resin has a recovery rate of 100 × 0.3228 / 0.5466 = 59.1% by a simple operation of adding the ion exchange resin to the solid lithium phosphate slurry and stirring it It was possible to recover a lithium-containing aqueous solution by elution with an acid. Moreover, only phosphoric acid remained in the solution (recovery rate as phosphorus (P) 100 × 0.7140 / 0.8131 = 87.8%), and an aqueous phosphoric acid solution was obtained.

In 100 ml of water, 3.02 g of the particulate lithium phosphate obtained in Example 1 was added and stirred to form a slurry. The pH of this slurry was 12.27. There are 0.8078 g of P and 0.5430 g of Li in the slurry. Next, about 50 g of granular ion exchange resin (Amberlight IR120B manufactured by Organo Corporation) was added in a swollen state while stirring the slurry. The slurry became a colorless and transparent solution by removing the ion exchange resin in 5 minutes. After stirring for 12 hours, the ion exchange resin was separated and recovered by filtration. The filtrate after separation and recovery of the ion exchange resin had a pH of 1.68, and in the solution, 0.7420 g of phosphorus and 0.0669 g of lithium were present. From the amount of phosphorus in the solution, the recovery rate as phosphorus can be calculated as 100 × 0.7420 / 0.8078 = 91.9%.
On the other hand, the recovered ion exchange resin was immersed in a hydrochloric acid aqueous solution in which 15 ml of 35% hydrochloric acid was mixed with 15 ml of pure water, followed by filtration, and the washings at the time of filtration were combined to obtain 42 ml of filtrate. No phosphorus was detected in the filtrate and the presence of 0.4617 g of lithium was observed.

From the above results, lithium can be recovered in the ion exchange resin with a recovery rate of 100 × 0.4617 / 0.5430 = 85.0%. Further, 8.86 g of powdered sodium carbonate was added to 28 ml of the filtered aqueous hydrochloric acid solution from which the solution subjected to the analysis of phosphorus and lithium was removed, resulting in pH = 11.25, 0.24 g. White precipitate was obtained. When the lithium content in this precipitate was examined, it was 18.50%, which was almost in agreement with the theoretical value 18.89% in lithium carbonate, and it was found that this precipitate was lithium carbonate .

10 g of lithium manganate containing 0.3749 g of lithium was immersed in a 1N aqueous hydrochloric acid solution overnight to form λ-MnO ₂ . The amount of lithium desorbed in the hydrochloric acid solution was 0.2773 g. When 0.82 g of granular lithium phosphate obtained in Example 1 was added to the above-mentioned λ-MnO ₂ containing slurry and it was filtered, lithium in the filtrate was 0.0073 g. On the other hand, 0.1081 g of lithium was present in the filtrate obtained by filtering the filtrate after stirring with 1 N hydrochloric acid. Since lithium in the added lithium phosphate can be calculated to be 0.1474 g, it was found that the recovery rate of lithium was 100 × 0.1081 / 0.1474 = 73.3%.

This technology, which can recover the raw materials of lithium from low concentration to high concentration such as lithium ion battery, which will be more and more important in the future, is used in large quantities especially in the automotive field such as EV and PHV The recovery and recycling technology of lithium ion secondary batteries, and the protection and recovery of lithium resources, which will be further valuable in the future, is extremely important and it is essential to put it to practical use.

Claims (16)

In an aqueous solution containing lithium, Adding phosphoric acid or phosphate to solidify the lithium as lithium phosphate; A step of separating solidified lithium phosphate; Adding the solidified lithium phosphate to water or an aqueous solution containing a lithium adsorbent, and developing the lithium phosphate to adsorb the lithium component of the lithium phosphate onto the adsorbent; 4. Separating the lithium-adsorbed adsorbent; A method for recovering lithium from a lithium-containing aqueous solution, comprising the step of desorbing adsorbed lithium from the adsorbent to obtain a concentrated aqueous solution of lithium. In an aqueous solution containing lithium, Adding phosphoric acid or phosphate to solidify the lithium as lithium phosphate; A step of separating solidified lithium phosphate; Developing the separated lithium phosphate in water to form a slurry; Then, a lithium adsorbent is added to the slurry to adsorb lithium, and Separating the lithium-adsorbed adsorbent; A method for recovering lithium from a lithium-containing aqueous solution, comprising the step of desorbing the adsorbed lithium from the adsorbent to which the lithium has been adsorbed to obtain a concentrated aqueous solution of lithium. The lithium recovery method according to any one of claims 1 and 2, wherein the phosphate is an alkali metal salt of phosphoric acid. The lithium recovery method according to any one of claims 1 and 2, wherein the solidified and precipitated lithium phosphate is separated by filtration. The lithium recovery method according to any one of claims 1 and 2, wherein the aqueous solution has an acidity of 10-12. The lithium recovery method according to any one of claims 1 and 2, wherein the lithium adsorbent is a γ-MnO2 adsorbent. The lithium recovery method according to any one of claims 1 and 2, wherein the lithium adsorbent is a cation exchange resin. The lithium recovery method according to claim 6, wherein the cation exchange resin is a carboxylic acid type weak ion exchange resin. The lithium recovery method according to claim 6, wherein the cation exchange resin is a sulfonic acid type strong ion exchange resin. The lithium recovery method according to any one of claims 1 and 2, wherein the lithium is desorbed in a hydrochloric acid aqueous solution. The lithium recovery method according to claim 1 or 2, wherein the lithium concentrated aqueous solution is a salt aqueous solution with an acid, and is recovered as a solid salt by evaporation to dryness of water. The lithium recovery method according to claim 1 or 2, wherein carbonate ions are added to the lithium-rich aqueous solution to recover lithium as lithium carbonate. The lithium recovery method according to claim 12, wherein the supply of the carbonate ion is performed by the addition of an alkali metal carbonate. The lithium recovery method according to claim 12 or 13, wherein the supply of the carbonate ion is performed by adding an aqueous sodium carbonate solution to the concentrated lithium aqueous solution. The lithium recovery method according to claim 12, wherein the supply of the carbonate ion is performed by adding calcium carbonate to the lithium rich aqueous solution. The lithium recovery method according to claim 1 or 2, wherein lithium is recovered as lithium hydroxide by adding calcium hydroxide and / or barium hydroxide to the lithium concentrated aqueous solution.