JP2003245542A - Lithium adsorbing agent and method for producing the same, and method for collecting lithium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adsorbing agent which practically adsorbs and collects lithium contained in sea water or water in watery environment such as geothermal hot water in a very small amount and has excellent selective adsorption of lithium at high adsorption speed and with large adsorption capacity, and is chemically stable and is repeatedly adsorbed/desorbed, provide a method for producing the same, and a method for collecting lithium using the same. <P>SOLUTION: This lithium adsorbing agent is composed of a λ-shaped manganese oxide obtained from a spinel lithium manganese oxide through the elution of lithium by acid treatment. The method for producing the adsorbing agent comprises firing manganese oxide or lithium hydroxide so as to obtain the spinel lithium manganese oxide, and eluting lithium therefrom through the acid treatment. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to selectively enriching lithium contained in a trace amount in environmental waters such as seawater and geothermal hot water.
The present invention relates to a lithium adsorbent made of λ-type manganese oxide used for collecting, a method for producing the same, and a method for collecting lithium from environmental waters such as seawater and geothermal hot water using the lithium adsorbent.

[0002]

2. Description of the Related Art There are many dissolved components in seawater, and it has been noted that the dissolved components should be collected based on their absolute size. Comparing the amount of elements in seawater with the estimated reserves on land, it is known that most of the elements have larger dissolved amounts in seawater. However, the elemental concentration in seawater is extremely low and industrially available ones are limited. Among these, sodium chloride, magnesium, bromine, potassium and the like can be mentioned as those currently industrialized.

Lithium, uranium, and the like have extremely low dissolved concentrations in seawater, but because of their high utility value, industrially applicable extraction techniques are being developed. Lithium has a promising future application such as a high-capacity battery, an additive element for light alloys for aircraft, and a fusion fuel.
Lithium has a higher concentration in seawater than uranium, which is 0.18 ppm on average, but sodium (1
It is necessary to selectively collect only lithium without accompanying a high-concentration coexisting metal such as 10,000 ppm). Various metal ions are dissolved in geothermal hot water such as hot spring water. Especially, lithium ioin has a much higher concentration than the dissolved concentration in seawater, and the concentration in geothermal hot water is about the same as that in seawater. It is 100 times, and a system for concentrating and collecting lithium from geothermal hot water such as hot spring water is also a promising industrial lithium collection system.

Various methods such as coprecipitation method, solvent extraction method, ion flotation method, precipitation flotation method, chromatographic method, and bioconcentration method are available as laboratory collection methods for trace components such as dissolved lithium. Yes, it has been applied to analytical chemical separation. However, the only industrially feasible method is the adsorption method. When collecting lithium in seawater by the adsorption method, it is necessary to bring a huge amount of seawater into contact with the adsorbent, and therefore development of a more highly efficient collection technique is desired. As a method of collecting lithium by adsorption, a method of adsorbing using aluminum hydroxide was initially noted, but the performance was far from practical use.

[0005]

DISCLOSURE OF THE INVENTION The present invention has an excellent selective adsorption property to lithium for industrially adsorbing and collecting lithium contained in seawater or geothermal hot water, and has a high adsorption rate and adsorption amount. It is an object of the present invention to provide an adsorbent that is large in size, chemically stable, and capable of repeating adsorption / desorption, a method for producing the same, and a method for collecting lithium using the same.

[0006]

The invention according to claim 1 for solving the above-mentioned problems is obtained by eluting lithium from a spinel type lithium manganese oxide using an acid.
It is a lithium adsorbent composed of manganese oxide.

The invention according to claim 2 is the lithium adsorbent according to claim 1, wherein the λ-type manganese oxide is in the form of fine particles or a film.

According to a third aspect of the invention, a step of mixing and pulverizing manganese tetraoxide and lithium hydroxide so that the molar ratio of manganese and lithium is 1.5 to 2.5,
Having a step of firing in an air atmosphere at a temperature range of 400 ° C. or higher to obtain spinel-type oxygen-rich lithium manganate, and a step of treating the spinel-type oxygen-rich lithium manganate with a large excess of acid to elute lithium. Is a method for producing a lithium adsorbent.

In a fourth aspect of the present invention, the step of mixing and pulverizing trimanganese tetraoxide and lithium hydroxide has a molar ratio of manganese to lithium of 2 (manganese: lithium =
The method for producing a lithium adsorbent according to claim 3, wherein the ratio is 2: 1).

According to a fifth aspect of the present invention, the step of obtaining spinel-type oxygen-rich lithium manganate is performed in a temperature range of 400 ° C. to 450 ° C. in an air atmosphere and 475 ° C. to 525 in an air atmosphere. The method for producing a lithium adsorbent according to claim 3 or 4, which comprises a two-step firing process of main firing performed in a temperature range of ° C.

According to a sixth aspect of the present invention, the step of treating the spinel type oxygen-rich lithium manganate with a large excess of acid to elute the lithium uses an acid having a concentration of 0.1M to 2M.
The method for producing a lithium adsorbent according to any one of claims 3 to 5, wherein a large excess of acid having a molar ratio of acid: lithium = 20: 1 or more is used.

According to a seventh aspect of the invention, the step of treating the spinel type oxygen-rich lithium manganate with a large excess of acid to elute the lithium uses an acid having a concentration of 0.1M to 2M.
The method for producing a lithium adsorbent according to any one of claims 3 to 6, wherein a large excess of acid having a molar ratio of acid: lithium = 40: 1 or more is used.

The invention according to claim 8 provides a lithium adsorbent comprising a λ-type manganese oxide obtained by eluting lithium from a spinel-type lithium manganese oxide with an acid, in an environment such as seawater or geothermal hot water. It is a method of collecting lithium, which is used for selective concentration of lithium contained in water.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The lithium adsorbent of the present invention has a layered λ
Type manganese dioxide-based adsorbent, the composition of which is H _X M
It has a spinel structure represented by n ₂ O ₄ . This spinel structure is the most important factor for the specific selective adsorption of lithium ions. The greatest feature of this structure is that it recognizes the size of lithium ions. Therefore, the layered λ-type manganese dioxide composition functioning as a lithium adsorbent of the present invention is an ion-sieving ionic shape-memory compound. Is. Due to this feature, it becomes possible to collect lithium, which is a trace component in environmental waters such as seawater and geothermal hot water, with high selectivity by eliminating coexisting high-concentration interfering ions such as sodium.

The layered λ type manganese dioxide composition of the present invention which functions as a lithium adsorbent has a particle size of 1 μm to 10 μm.
It is in the form of fine particles or a film of 0 μm. The layered λ-type manganese dioxide composition having this spinel structure has a lattice constant a = 7.99Å (± 0.00Å), b = 8.04Å
(± 0.00Å), c = 8.03Å (± 0.00Å),
α = 89.9 ° (± 0.01 °), β = 89.7 ° (±
0.03 °), γ = 89.9 ° (± 0.01 °), and volume: 515.24Å ³ (σ = 0.00029Å ³ ).

The manufacturing process of the lithium adsorbent of the present invention will be described below.

Functions as a lithium adsorbent of the present invention
Used when producing a layered λ-type manganese dioxide composition
Spinel type lithium manganate (General composition: LiMn
_TwoO _Four) Is known as a battery material and is commonly referred to as acid.
By heating the mixture of manganese oxide and lithium salt
Obtained. At that time, mixing manganese oxide and lithium salt
By changing the ratio, firing temperature, time, etc.,
Various compositions can be obtained.

In this embodiment, it is obtained as follows. That is, trimanganese tetraoxide (Mn ₃ O ₄ ) and lithium hydroxide monohydrate (LiOH.H ₂ O) are used, and the molar ratio of manganese to lithium is 1.5: 1 to 2.5: 1, preferably Is mixed and crushed to be 2: 1. This mixed and crushed material is subjected to 1 at a temperature range of 400 ° C to 450 ° C in an air atmosphere.
Temporary baking for 10 hours. After the calcination, the calcinated product is mixed and pulverized, and this is calcinated in an air atmosphere at a temperature range of 475 ° C. to 525 ° C. for 1 hour to 10 hours. Here, it is necessary to carefully perform a series of mixing and pulverization in order to uniformly impregnate trimanganese tetraoxide (Mn ₃ O ₄ ) with lithium hydroxide. In this way, high-purity spinel-type oxygen-rich lithium manganate (LiMn ₂ O _{4 + b} ) can be obtained. According to the knowledge of the inventors, the spinel type lithium manganate obtained only by the main calcination has many impurities, and when this is acid-treated to elute lithium, the crystal structure collapses, and a layered λ-type manganese dioxide composition is obtained. Hard to get.

The obtained spinel-type lithium with excess oxygen manganate (LiMn ₂ O _{4 + b} ) is acid-treated to obtain a λ-type manganese dioxide composition. That is, an acid is applied to spinel type oxygen-rich lithium manganate to elute lithium by an ion exchange reaction.

When eluting lithium from spinel type oxygen-rich lithium manganate with an acid, a large excess of acid such as hydrochloric acid, perchloric acid, nitric acid, etc. is used, and the molar ratio of lithium to acid exceeds 1:20, preferably lithium. : Acid = 1: 4
It is necessary to elute lithium with an excess acid of 0 or more. The acid concentration at this time is 0.1M to 2M. Two
Applying an acid concentration exceeding M is not preferable because it dissolves Mn.

By eluting lithium with a large excess of the acid, the redox reaction of manganese can be suppressed and only the ion exchange reaction of hydrogen ion and lithium ion can be caused. According to the knowledge of the inventors, the number of moles of acid:
When lithium is eluted from the spinel-type oxygen-rich lithium manganate with an acid with the molar number of lithium being 10: 1 or 20: 1, the crystal structure of λ-type manganese dioxide is destroyed. The reason is that when the lithium is eluted from the spinel type oxygen-rich lithium manganate with an acid, the redox reaction of manganese and the ion exchange reaction of hydrogen ions and lithium ions simultaneously proceed. At that time, in order to obtain high-purity λ-type manganese dioxide, without changing the valence of manganese, in other words, without causing a redox reaction, ion exchange of hydrogen ions and lithium ions should be performed as much as possible. Only the reaction needs to occur. Thus, the molar ratio of lithium to acid is greater than 1:20, preferably lithium:
When lithium is eluted with an excess acid of acid = 1: 40 or more, the redox reaction of Mn can be suppressed and only the ion exchange reaction between hydrogen ions and lithium ions can occur.

The acid used for eluting lithium from the spinel type oxygen-rich lithium manganate with an acid is preferably a mineral acid, and hydrochloric acid, perchloric acid or nitric acid can be used. According to the knowledge of the inventors, the use of an aqueous sulfuric acid solution is not preferable because the crystal structure of the obtained λ-type manganese dioxide is destroyed.

In order to selectively adsorb and collect lithium dissolved in seawater using the layered λ-type manganese dioxide composition obtained by the process for producing a lithium adsorbent of the present invention, the adsorbent is used. It is necessary to carry out granulation in order to fill the column with and to improve the liquid passing state. In this embodiment, after dissolving polyvinyl chloride in tetrahydrofuran as a binder,
While stirring with a stirrer, the λ-type manganese dioxide composition is charged and stirred for a while, and when bubbles are removed, a 1: 1 methanol aqueous solution is vigorously stirred and charged all at once. The composition is filtered under reduced pressure, washed with distilled water, and dried at a temperature of 60 ° C., for example. After drying overnight, it is sieved to give a particulate adsorbent of the desired size. The particle size of the particulate adsorbent can be changed within the range of 150 μm to 1 mm.

[0024]

Example: Manganese tetraoxide (Mn)_ThreeO_Four) And hydroxide
Titanium monohydrate (LiOH ・ H _TwoO) with manganese
In an agate mortar so that the molar ratio of lithium is 2: 1
Mix and crush for 15 minutes. The obtained mixed pulverized product is air
Pre-baking for 5 hours in an electric furnace maintained at 425 ° C in the atmosphere
I went. Temporarily calcined product is cooled and then mixed and powdered for 15 minutes
After crushing, it was put in an electric furnace maintained at 500 ° C again in an air atmosphere.
Main firing was performed for 5 hours. Thus, spinel type oxygen
Lithium manganate (LiMn_TwoO_{4 + b}) Got.
The resulting spinel-type oxygen-rich lithium manganate was mixed with X
Confirmed by line diffraction.

This spinel type oxygen-rich lithium manganate (LiMn ₂ O _{4 + b} ) and hydrochloric acid having a concentration of 1.0 M were
A large excess of acid with a molar ratio of lithium to acid of 1:40 was mixed and stirred for 24 hours. This operation was repeated 5 times to obtain the desired λ-type manganese dioxide-based adsorbent. Obtained λ
The content of lithium in manganese dioxide type is LiMn ₂
When the lithium in O ₄ is 100%, it contains 3.6% of lithium, that is, the composition formula Li _0.036 Mn ₂ O.
It was _{4 + b} . Further, it has been clarified that the b value in the oxygen composition is 0 or more, but the details are unknown.
This λ-type manganese dioxide was confirmed by X-ray diffraction.

X-ray diffraction pattern of spinel-type oxygen-rich lithium manganate obtained by calcination and main calcination and λ-type manganese dioxide obtained by eluting lithium by repeating treatment with a large excess of the acid for 5 times. Is shown in FIG. In FIG. 1, from the bottom, spinel-type oxygen-rich lithium manganate, moles of lithium: moles of acid = 1: 40
Shows the peak of the object to be treated after 1 to 5 times of treatment with a large excess of acid. The X-ray diffraction pattern confirmed that it was the desired spinel type lithium manganate, and
It was confirmed that the treatment with the large excess of acid effectively elutes only lithium while keeping the spinel structure.

For example, the obtained λ-type manganese dioxide composition was granulated to facilitate the passage of lithium in seawater by adsorption separation / collection by a column. Polyvinyl chloride 0.1g as a binder, tetrahydrofuran 6m
After completely dissolving in 1 l, it was lightly washed with distilled water and dried at 60 ° C. in a dryer. After drying overnight, it was sieved to obtain a granular adsorbent of desired size.

The following tests were conducted for the purpose of investigating the adsorption characteristics of the λ type manganese oxide type lithium adsorbent of the present invention.
Tests 1 to 5 were performed by a batch method of shaking in a thermostat set to 303K. As the aqueous solution, a 0.1 M ammonium chloride-ammonia buffer solution containing 5 mM concentration of lithium and adjusted to pH: 8.1 was used. Adsorption was performed by shaking 10 ml of such an aqueous solution and 0.02 g of the adsorbent or the granular adsorbent.

Test 1 Spinel type oxygen-rich lithium manganate (LiMn ₂ O
The relationship between the number of acid treatments for _{4 + b} ) and the amount of lithium adsorbed by the adsorbent was investigated. Under the above conditions, the test was performed on each of the acid-treated products 1 to 5 times. The results are shown in Table 1 and FIG. As is clear from Table 1 and FIG. 2, no increase in the amount of adsorbed lithium was observed at the 4th and 5th acid treatments, confirming that 5 acid treatments were sufficient.

[0030]

[Table 1]

Test 2 To investigate the adsorption rate by the lithium adsorbent of the present invention,
The equilibrium arrival time of the adsorption amount was investigated. Under the above conditions, shaking time is 1 hour, 2 hours, 5 hours, 10 hours 15 hours, 24 hours.
The time was set and tested. The test results are shown in Table 2 and FIG. Shaking 1 as apparent from Table 2 and FIG.
Equilibrium is almost reached in about time. This is because the lithium adsorbent of the present invention is an ion exchanger. From this, it was confirmed that the lithium adsorbent of the present invention can efficiently recover industrial lithium.

[0032]

[Table 2]

Test 3 The pH dependency of the adsorbent on lithium adsorption was investigated.
Under the above conditions, the initial pH of the aqueous solution was 6.0, 7.0,
Shaking was performed for 5 hours with settings of 8.0, 8.3, 8.5, 8.8, and 9.0. The results are shown in Table 3 and FIG. As is clear from Table 3 and FIG. 4, since the lithium adsorbent of the present invention is an ion-exchangeable adsorbent that releases hydrogen ions and replaces them with lithium ions, a large adsorption amount was exhibited in the alkaline region.

[0034]

[Table 3]

Test 4 Considering the collection of lithium from seawater, the selective adsorption of lithium of the adsorbent of the present invention in the presence of a high concentration of sodium ion was examined. The above buffer solution was used as an aqueous solution, and the metal concentration was such that lithium was fixed at 5 mM and coexisting sodium was changed within the range of 5 mM to 4000 mM. The test results are shown in Table 4 and FIG. As is clear from Table 4 and FIG. 5, sodium / lithium is 800
No change in the amount of adsorbed lithium is seen even when the number of times reaches double. Thus, the high selective adsorption of the lithium adsorbent of the present invention was confirmed.

[0036]

[Table 4]

Test 5 The equilibrium arrival time of the granular adsorbent for adsorption columns obtained by the granulation method in the examples of the present invention was examined. The test conditions are the same as in Test 2. The test results are shown in Table 5.
And shown in FIG. The influence of polyvinyl chloride as a binder was considered, but as is clear from Table 5 and FIG. 6, the adsorption rate and the adsorption amount did not decrease, and the adsorption amount and adsorption rate were similar to those of the adsorbent. It was confirmed that
The lithium adsorbent of the present invention can increase the size of particles without causing a decrease in performance.

[0038]

[Table 5]

Test 6 Lithium and sodium were adsorbed and separated by adsorption column chromatography in which a solution was supplied using a medium pressure ceramics pump (liquid feeding pump) 2 shown in FIG. This lithium / sodium adsorption / separation device uses a high-concentration hydrochloric acid, and is therefore equipped with a washing pump. A pressure resistant column having a diameter of 5 mm and a total length of 100 mm was used as the adsorption column 1, and the flowing liquid was sampled by the fraction collector 3 at a predetermined time. In FIG. 7, 11 is a granular adsorbent, 12 is glass beads, and 13 is cotton.

The adsorption separation of lithium by adsorption column chromatography was performed as follows. 0.5 g of the granular adsorbent to be packed in the column was preliminarily immersed in distilled water overnight for swelling, and then packed in the column shown in FIG. Next, a 0.1 M ammonium chloride-ammonia buffer solution containing no metal and adjusted to pH: 8.1 was passed for 3 hours. Then, use lithium and sodium as chlorides to 40
The above buffer solution containing a concentration of ppm was supplied, and the concentrations of lithium and sodium in the outlet liquid were measured. After that, a 0.1 M ammonium chloride / ammonia buffer solution containing no metal and adjusted to pH: 8.1 is passed for 3 hours to wash the surface of the granular adsorbent, and then distilled water is passed for 1 hour. Liquor
As an elution operation, 1 M hydrochloric acid was supplied and the outlet liquid was measured in the same manner as above. The volume of the granular adsorbent was 1.18 cm ^3.
The solution was supplied at a flow rate of 0.33 ml / min for both adsorption and elution.

The test results are shown in Table 6 and FIG. The results of the elution test are shown in Table 7 and FIG.

[0042]

[Table 6]

[0043]

[Table 7]

As shown in FIG. 9, an eluent containing a maximum of 3000 ppm of lithium and 4 ppm of sodium was obtained in the elution process. That is, it showed a selective adsorptivity reaching a molar ratio of lithium / sodium of 2300 times. In this way, lithium is separated into high concentrations with high selective adsorption.
Succeeded in concentrating.

[0045]

INDUSTRIAL APPLICABILITY The lithium adsorbent comprising the layered λ type manganese dioxide composition of the present invention or the granular adsorbent obtained by granulating the lithium adsorbent is an ion sieve type ionic shape memory compound that recognizes the size of lithium ions. Therefore, it has a specific selectivity for lithium ions and an excellent selective adsorption property for lithium.

According to the inventions of claims 3 to 7, a lithium adsorbent comprising a highly pure layered λ-type manganese dioxide composition can be produced. Further, according to the lithium extraction method using the lithium adsorbent composed of the layered λ-type manganese dioxide composition obtained by this process, a small amount of dissolved lithium in seawater or geothermal water can be extracted with high efficiency.

[Brief description of drawings]

FIG. 1 is a graph showing an X-ray diffraction pattern of a spinel-type lithium manganese oxide which is an intermediate product of a lithium adsorbent of the present invention and an object to be treated which has been treated with acid 1 to 5 times (eluting lithium)

FIG. 2 is a graph showing the relationship between the number of acid treatments and the amount of lithium adsorbed on spinel-type lithium manganese oxide.

FIG. 3 is a graph showing the relationship between shaking time and lithium adsorption amount.

FIG. 4 is a graph showing the pH dependence of an adsorbent on lithium adsorption.

FIG. 5 is a graph showing the test results of the selectivity of the adsorbent for lithium in the presence of sodium ions.

FIG. 6 is a graph showing an equilibrium arrival time of a granular adsorbent.

FIG. 7 is a block diagram showing an adsorption separation device for lithium and sodium by adsorption column chromatography according to an embodiment of the present invention.

FIG. 8 is a graph showing the results of adsorption separation of lithium and sodium by adsorption column chromatography according to an example of the present invention.

FIG. 9 is a graph showing the results of an elution test of lithium and sodium by adsorption column chromatography according to an example of the present invention.

[Explanation of symbols]

1 column 11 Granular adsorbent 12 glass beads 13 cotton 2 Liquid feed pump 3 fraction collector

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masao Yoshio             592-29 Honjo, Honjo-cho, Saga City, Saga Prefecture (72) Inventor Hideyuki Noguchi             1684 Tokutomi, Morotomi Town, Saga Group, Saga Prefecture F-term (reference) 4D017 AA01 BA11 CA05 CB01                 4D024 AA05 AB15 BA14 BB01 BB05                 4G048 AA04 AB02 AB05 AC08 AD02                       AD03 AD06 AE05                 4G066 AA13A AA26B AC15D CA45                       DA07 FA01 FA11 FA22 FA26                       FA34 FA37                 5H050 AA19 BA05 BA15 CA09 GA05                       GA10 GA14

Claims (8)

[Claims] 1. A lithium adsorbent comprising a λ-type manganese oxide obtained by eluting lithium from a spinel-type lithium manganese oxide with an acid. 2. The lithium adsorbent according to claim 1, wherein the λ-type manganese oxide is in the form of fine particles or a film. 3. A step of mixing and pulverizing trimanganese tetraoxide and lithium hydroxide so that the molar ratio of manganese to lithium is 1.5 to 2.5, and 400 ° C. in an air atmosphere.
Lithium adsorption characterized by having a step of firing in the above temperature range to obtain spinel type oxygen-rich lithium manganate and a step of treating the spinel type oxygen-rich lithium manganate with a large excess of acid to elute lithium Method of manufacturing agent. 4. The lithium according to claim 3, wherein the step of mixing and pulverizing trimanganese tetraoxide and lithium hydroxide sets the molar ratio of manganese to lithium to 2 (manganese: lithium = 2: 1). Method for producing adsorbent. 5. The step of obtaining spinel type oxygen-rich lithium manganate is performed in a temperature range of 400 ° C. to 450 ° C. in an air atmosphere and 475 ° C. in an air atmosphere.
The method for producing a lithium adsorbent according to claim 3 or 4, which comprises a two-step firing process of main firing performed in a temperature range of 525 ° C. 6. A step of treating spinel-type oxygen-rich lithium manganate with a large excess of acid to elute lithium,
An acid having a concentration of 1M to 2M is used, and a molar ratio of acid: lithium =
The method for producing a lithium adsorbent according to claim 3, wherein a large excess of acid exceeding 20: 1 is used. 7. A step of treating spinel-type oxygen-rich lithium manganate with a large excess of acid to elute lithium,
An acid having a concentration of 1M to 2M is used, and a molar ratio of acid: lithium =
4. Use of a large excess of acid of 40: 1 or more.
7. The method for producing a lithium adsorbent according to claim 6. 8. A lithium adsorbent comprising a λ-type manganese oxide obtained by eluting lithium from a spinel-type lithium manganese oxide with an acid is selected as a lithium adsorbent contained in environmental waters such as seawater and geothermal hot water. A method for collecting lithium, which is used for effective concentration.