JPH038439A - Granular lithium adsorbent and method for recovering lithium by using this adsorbent - Google Patents

Abstract

PURPOSE:To efficiently recover lithium from a dilute soln. by using a material in which the lithium is eluted by treating the granular matter of a lithium contg. manganese oxide formed by granulating an org. high-polymer material with an aq. soln. having lithium elutability. CONSTITUTION:The lithium-contg. manganese oxide, such as LiMn2O4 or Li2 MnO3, is added into the soln. prepd. by dissolving the org. high polymer material having a binder function into au org. solvent and is then sufficiently kneaded. The mixture is passed through a capillary in a liquid which has affinity to the org. solvent and is a nonsolvent to the high-polymer material, by which the granular matter is produced. The granular matter is then immersed into an aq. soln. of <=4 pH contg. the acid having the lithium elutability or an oxidative material exhibiting acidity to elute the lithium. The granular lithium adsorbent is thus obtd. This adsorbent is packed into a column where the dilute soln. contg. the lithium is passed to adsorb the lithium on the adsorbent. A soln. for desorbing the lithium is then passed in the column to elute the lithium adsorbed on the adsorbent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel granular lithium adsorbent and a lithium recovery method using the same.

More specifically, the present invention provides a granular lithium adsorbent that has excellent selective adsorption for lithium, has a large adsorption capacity and rate, is stable in an aqueous solution, has low toxicity, and is easy to handle. The present invention relates to a method for efficiently recovering lithium from a dilute solution using a device.

Background of the Invention In recent years, lithium metal and its compounds have been used in many fields for various applications, such as ceramics, batteries, refrigerant absorbents, and pharmaceuticals. The demand for lithium is expected to increase significantly as it is expected to be used as fuel, etc. [Journal of the Japan Mining Association, Vol. 79,
Page 221].

The lithium metal and its compounds are currently produced mainly from lithium-containing ores such as spodumene, ambrigonite, petalite, and lepidolite, as well as salt lakes and underground shrubs with high lithium concentrations.

However, our country does not have the above-mentioned lithium ore resources, and currently relies entirely on imports for lithium metal and its compounds.

On the other hand, some geothermal water and hot spring water in Japan contain a considerable amount of lithium, and the surrounding seawater also contains small amounts of lithium. Therefore, it is strongly desired to establish a technique for efficiently recovering lithium from these dilute solutions containing lithium.

Conventionally, various adsorbents have been developed to recover lithium from solutions containing lithium such as seawater and brine. For example, amorphous aluminum hydroxide (Japanese Patent Laid-Open No. 55
-10541), hydrated tin oxide (Japanese Unexamined Patent Publication No. 57-6
1623), tin antimonate (Japanese Unexamined Patent Publication No. 58-1
67424), bismuth phosphate (JP-A-59-1)
95525), titanic acid heat-treated product (JP-A-61
-72623), manganese oxide (JP-A-61-
171535, 61-228334), etc. are known.

Among these adsorbents, manganese oxide-based adsorbents in particular exhibit high lithium selectivity, and their adsorption amount is comparable to the lithium content of low-grade ores, making them the closest adsorbent to practical use. It is expected. This adsorbent is produced by introducing lithium ions or magnesium ions into a porous manganese hydrous oxide in advance and fixing them, and then eluting the lithium ions or magnesium ions by acid treatment or the like. Therefore, it is characterized by the formation of extremely fine pores suitable for lithium in the adsorbent.

However, since the adsorbent is usually a powder, it has the disadvantage that it is extremely difficult to separate and recover it from the solution when it is brought into contact with a large amount of seawater or brine. This is a major impediment to its practical application.

Problems to be Solved by the Invention The present invention overcomes the drawbacks of conventional lithium adsorbents, has excellent selective adsorption for lithium, has a high adsorption rate and adsorption capacity, and is capable of separating dilute lithium solutions. A practical granular form for recovering lithium from dilute solutions such as lithium-containing seawater, geothermal water, and underground bushes, which is easy to recover, has low toxicity, and is stable in dilute solutions. The purpose of this invention is to provide a lithium adsorbent and a method for efficiently recovering lithium from a dilute solution using the adsorbent.

Means for Solving the Problems In order to achieve the above object, the inventors of the present invention have conducted extensive research and found that after forming lithium-containing manganese oxide into granules using an organic polymeric substance as a binder, they formed them into a granular material using an aqueous solution. By eluting the lithium in a column, a granular lithium adsorbent having the above-mentioned desirable properties can be obtained, and after filling a column with this material and flowing a dilute solution containing lithium therein to adsorb lithium, discovered that lithium can be efficiently recovered from a dilute solution by eluting lithium adsorbed on an adsorbent using an aqueous solution that has lithium desorption ability, and based on this knowledge, the present invention was completed. .

That is, the present invention provides a granular lithium characterized in that a granular body of lithium-containing manganese oxide granulated using an organic polymer substance is treated with an aqueous solution having lithium elution ability to elute the lithium. After filling a column with an adsorbent and this granular lithium adsorbent, a dilute solution containing lithium is flowed through the column to adsorb lithium, and then a dilute acid solution or an aqueous solution containing an oxidizing compound exhibiting acidity is used. , provides a method for recovering lithium from a dilute solution, characterized in that lithium adsorbed on the adsorbent is eluted.

The present invention will be explained in detail below.

The manganese oxide used as a raw material for the lithium adsorbent of the present invention is not particularly limited as long as it contains lithium, but examples include LiMn and O.

or Li2MnO3 is preferably used. Such a lithium-containing manganese oxide is produced by adsorbing lithium onto a porous manganese hydrate, for example, and then
Method of heat treatment at a temperature of 00°C or higher
171535), a method in which a mixture of manganese hydroxide oxide and lithium carbonate is heat-treated at a temperature of 200° C. or higher (Japanese Patent Application Laid-open No. 80844/1984), and the like. The particle size of the lithium-containing manganese oxide obtained in this way is usually 01-100.
In the present invention, it is in the range of 0.1-10μm.
Those having a particle size of m are preferably used.

The organic polymer used in the adsorbent of the present invention is not particularly limited as long as it has a function as a binder, but examples include polyvinyl chloride, acrylonitrile copolymer, polysulfone, polyamide, polyimide, polyester, etc. Examples include acetyl cellulose.

In order to produce the granular adsorbent of the present invention, lithium-containing manganese oxide as a raw material is first granulated using the organic polymer substance described above to prepare granules. A lithium-containing manganese oxide is added to a solution in which the polymeric substance is dissolved and thoroughly kneaded, and the kneaded product is mixed with a solution having an affinity for the organic solvent and a non-solvent for the polymeric substance. It can be prepared by dropping it through a capillary. The particle size of the granules can be adjusted by the diameter of the capillary and the dropping rate.

Examples of the non-solvent include water, acetone, alcohol, etc., and water is preferred from the viewpoint of ease of handling. Further, the organic solvent used to dissolve the polymeric substance is appropriately selected depending on the type of the non-solvent. For example, when water is used as the non-solvent, the organic solvent may be dimethylformamide, formamide, Dimethyl sulfoxide, dioxane, tetrahydrofuran, acetone and the like are preferably used.

The amount of the polymeric substance used is usually selected in the range of 5 to 60% by weight based on the lithium-containing manganese oxide. If this amount is less than 5% by weight, the polymer substance will not be uniformly dispersed in the granules, and the granules will likely be crushed or powdered.
If it exceeds 60% by weight, it becomes difficult to elute lithium from the manganese oxide, and adsorption performance tends to decrease.

After the granules obtained in this way are thoroughly washed with water,
treated by immersion in an aqueous solution having lithium elution ability,
The lithium contained therein is eluted. As the aqueous solution having the ability to elute lithium, an aqueous solution containing an acid or an oxidizing substance exhibiting acidity and having a pH of 4 or less is preferably used. Preferred examples of the acid include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, with hydrochloric acid being particularly preferred.

There are no particular restrictions on the concentration of the aqueous solution containing these acids, but a concentration of 0.05 to 0.5M is usually used. Room temperature is sufficient for the treatment temperature, and the treatment time is usually several hours or more, although it depends on the acid concentration.

On the other hand, the oxidizing substance exhibiting acidity is not particularly limited as long as it is an oxidizing agent exhibiting weak acidity in an aqueous solution. Examples of such substances include belloxonisulfate and bromine, but ammonium belloxonisulfate is preferred from the viewpoint of economy, ease of handling, solubility, and the like. Although there is no particular restriction on the concentration of this acidic oxidizing substance, a concentration of 0.1 to IM is usually used. The treatment temperature is usually selected within the range of 40°C to the boiling point. If this temperature is less than 40°C, it will take a long time to elute lithium.
Not practical.

By treating the granules with an aqueous solution capable of eluting lithium in this way, about 90% or more of the lithium contained in the manganese oxide is eluted, and a granular lithium adsorbent is obtained.

In order to recover lithium from a dilute lithium solution using the granular lithium adsorbent of the present invention thus obtained, the granular lithium adsorbent is packed into a column, and a dilute solution containing lithium is poured into the column. Lithium may be adsorbed, and then the lithium adsorbed on the adsorbent may be eluted using a dilute acid solution or an aqueous solution containing an oxidizing substance exhibiting acidity.

Furthermore, since the granular adsorbent of the present invention has good stability against a dilute solution containing lithium and a solution for lithium desorption, a dilute solution containing lithium and a lithium desorption solution are added to a column containing the granular adsorbent. By alternately flowing the water, adsorption and desorption can be repeated.

Effects of the Invention The granular lithium adsorbent of the present invention has excellent selective adsorption properties for lithium, and has a large adsorption capacity and adsorption rate.
It is easy to separate and recover from dilute lithium solutions, has low toxicity, and is stable in dilute lithium solutions and lithium desorption solutions. It is suitably used as a practical lithium adsorbent for recovering lithium from dilute solutions.

In addition, since the granular lithium adsorbent of the present invention has the excellent characteristics described above, the adsorbent is packed in a column, and a dilute solution containing lithium and a lithium desorption solution are alternately poured into the column. By repeating adsorption and desorption,
Lithium can be recovered from dilute solutions extremely efficiently.

Although it is possible to granulate the powdered lithium adsorbent obtained by pre-acid treatment of lithium-containing manganese oxide using a polymeric material as a binder as described above, powdered lithium adsorption is not possible. Since the agent is unstable in organic solvents, the active sites are destroyed during granulation, and the resulting granules exhibit almost no lithium adsorption ability.

Examples Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited in any way by these examples.

Example 1 After pulverizing and mixing 500 g of manganese hydroxide oxide and 103 g of lithium carbonate, heat treatment was performed at 400°C for 5 hours to obtain M
- A rum-containing manganese rim was prepared. As a result of X-ray analysis, it was confirmed that a phase of LiMn20 was formed.

Next, 4 g of polyvinyl chloride (polymerization degree 2000) was dissolved in 40 mQ of tetrahydrofuran (2 and N,N-dimethylformamide 40 mQ), and the log of the lithium-containing manganese oxide was added to this solution and thoroughly kneaded. The suspension was dropped into water through a capillary tube with a diameter of 1.5 m++1 to produce granules.

Next, 5 g of this granule was added to 2 ml of 0.25 M hydrochloric acid solution at room temperature.
The lithium was eluted by dipping in Q. FIG. 1 graphically shows the change over time in the lithium elution rate of the granules.

From FIG. 1, it can be seen that most of the lithium in the granules is eluted after a treatment time of 4 hours, and the elution rate becomes almost constant over 24 hours.

Five types of granular adsorbents with different hydrochloric acid treatment times were manufactured, 1 g of each was packed into a column with a diameter of 3.5 cm, and natural sea water was flowed through the column at a rate of 50 m/min for 7 days to conduct an experiment on adsorption of lithium from seawater. . The amount of lithium adsorbed at that time is shown in Table 1.

Table 1 As can be seen from Table 1, the amount of lithium adsorption is between 2.3 and 2.
．． 5 my/g, and a good result was obtained.

Example 2 A granular material of lithium-containing manganese oxide was prepared in the same manner as in Example 1, and 5 g of the granular material was placed in 300 ml of a 0.5 M aqueous ammonium oxonisulfate solution and treated at 700C. FIG. 2 graphically shows the relationship between treatment time and lithium elution rate. From this Figure 2, it is clear that ammonium oxonisulfate ((NH,)zszo
In the case of a), the dissolution rate is 97% or more in 1 hour,
It turned out that the process can be done in an extremely short time.

Next, 0.5 g of four types of granular adsorbents with different treatment times
After preparing, it was immediately filled into a column with a diameter of 3.5 cm, and an adsorption experiment was conducted by flowing natural seawater at a flow rate of 50 mQ1 min for 7 days. In addition, each of the same granular adsorbents (0.59 g) was stored in water for one month and then subjected to an adsorption experiment under the same conditions. The results are shown in Table 2.

Table 2 As can be seen from Table 2, the amount of lithium adsorption is between 2.1 and 2.
．． 6+++ g/g, and the highest adsorption amount (
2.4-2.6 mg/g) was obtained. In addition, the prepared adsorbent was stable and no influence due to changes over time was observed. Thus, the granular adsorbent of the present invention showed excellent performance.

Example 3 To 10 g of lithium-containing manganese oxide prepared in the same manner as in Example 1, a solution of 49 polyvinyl chloride (degree of polymerization 700) dissolved in 50 mf2 of N,N-dimethylformamide was added and thoroughly kneaded. ;. This is 1.5m in diameter + R
was dropped into a mixture of water and alcohol through a thin tube to obtain granular lithium manganese oxide.

Next, 5 g of this granular material was placed in 2Q of 0.25M hydrochloric acid solution, and treated for 4 days with stirring to elute lithium. FIG. 3 shows a graph of the relationship between treatment time and lithium elution rate. As can be seen from FIG. 3, a lithium elution rate of 90% or more was obtained after one day of hydrochloric acid treatment, but little change in the elution rate was observed when the treatment time was longer than that.

Next, an adsorption experiment was conducted under the same conditions as in Example 2 using four types of granular adsorbent species 59 having different treatment times.

The results are shown in Table 3.

Table 3 The adsorption treatment conditions were the same as in Example 3, and the desorption treatment was performed by immersing the granular adsorbent in 0.25M hydrochloric acid solution for 8 hours. The results are shown in Table 4.

Table 4 The amount of lithium adsorbed was 2.1 to 3.0 mg/9, and this value was about the same as in Examples 1 and 2, indicating that the degree of polymerization of the added polyvinyl chloride did not affect the lithium adsorption property. I understand.

Example 4 Using granular adsorbents prepared under the same conditions as No. 1 of Example 3, a repeated absorption-desorption test was conducted.

As can be seen from Table 4, there was no decrease in adsorption performance after repeated use three times, and the desorption rate remained almost constant.
Good results were obtained. Furthermore, during this treatment process, no finer particles of the granular adsorbent were observed and it was stable.

It has been found that the use of the particulate adsorbent of the present invention enables column processing to efficiently recover lithium from dilute lithium solutions.

Comparative Example 20g of lithium-containing manganese oxide powder prepared in the same manner as in Example 1 was placed in 0.25M hydrochloric acid solution 2Q and treated with stirring for 4 days to elute lithium and obtain a powdered lithium adsorbent. .

Next, using this powdered adsorbent, granules were prepared by granulating in the same manner as in Example 1, and 5 g of this sail was 3.5 cm in diameter.
After filling the rn column, add 50% natural seawater to it.
A lithium adsorption experiment from seawater was conducted by flowing the water at a rate of mQ 1 min for 7 days. As a result, the amount of lithium adsorbed was O, 1 mg.
/g or less, and it was found that almost no lithium adsorption property was exhibited.

[Brief explanation of the drawing]

Figures 1, 2, and 3 respectively show the treatment time and lithium when lithium-containing manganese oxide particles are treated with an aqueous solution having lithium elution ability in different production examples of the granular lithium adsorbent of the present invention. It is a graph showing the relationship with elution rate. Figure 0 1 2 3 (N) 4%)z Sz 099-' Kneading B% Fll'
? CB%f%'S) Yuo 40
6゜HC1 submission P5 (time) 1 2 3 HC1g! L soil g B: between (8)

Claims (1)

[Scope of Claims] 1. Granules characterized in that granules of lithium-containing manganese oxide granulated using an organic polymer substance are treated with an aqueous solution having lithium elution ability to elute the lithium. Lithium adsorbent. 2 Lithium-containing manganese oxide is LiMn_2O_4
The granular lithium adsorbent according to claim 1, which contains Li_2MnO_3. 3. The granular lithium adsorbent according to claim 1 or 2, wherein the organic polymer substance is soluble in an organic solvent miscible with water and insoluble in water or a mixed solvent of water and alcohol. 4. Claim 1, wherein the aqueous solution having lithium elution ability contains an acid or an oxidizing substance exhibiting acidity and has a pH of 4 or less.
, 2 or 3. The granular lithium adsorbent according to . 5. After filling a column with the granular lithium adsorbent according to claim 1, a dilute solution containing lithium is poured into the column to adsorb lithium, and then a dilute acid solution or an aqueous solution containing an oxidizing compound exhibiting acidity is used. A method for recovering lithium from a dilute solution, comprising: eluting lithium adsorbed by the adsorbent.