JPS61283341A - Novel method for preparing lithium adsorbent - Google Patents

Abstract

PURPOSE:To obtain an Li-adsorbent excellent in selective adsorbability and having large adsorbing capacity, by grinding and mixing an Li-compound and an Mn-compound and applying heat treatment to the resulting mixture at specific temp. to prepare an Li-containing Mn-compound which is, in turn, treated with an acid to elute Li. CONSTITUTION:An Li-compound (e.g., Li-oxide or Li-carbonate) and an Mn- compound (e.g., Mn-oxide or Mn-carbonate) are respectively ground and mixed. Subsequently, the resulting mixture is subjected to heat treatment at 500 deg.C or more, pref., at 700 deg.C or more for 10min or more to obtain an Li-containing Mn-compound with Li-content of 0.5-20wt%. This Mn-compound is treated at pH3 or less pref. by using 0.05N or more mineral acid to elute Li to obtain an Li-adsorbent having a large number of micropores. This adsorbent is excellent in selective adsorbability to Li and has large adsorbing capacity and a high adsorbing speed and is low in toxicity and inexpensive.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing a lithium adsorbent. More specifically, the present invention provides a method for producing a lithium adsorbent that has excellent selective adsorption for lithium, has a large adsorption capacity and rate, is stable in a dilute lithium solution, has little toxicity, and is inexpensive.

In recent years, lithium metal and its compounds have been used in many fields, such as ceramics, batteries, absorption refrigerants, and pharmaceuticals, and in the future, they are being considered for use in large-capacity batteries, aluminum alloy materials, nuclear fusion fuels, etc. The demand for lithium is expected to increase significantly [Journal of the Japan Mining Association, Vol. 97, p. 221].

The lithium metal and its compounds are currently used in lithium-containing ores (with a lithium content of 2 to 6
%), and salt lakes and underground brine (lithium concentration 50 to 200 ppm) 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. In addition, trace amounts of lithium (0.17
ppm). Therefore, it is strongly desired to establish a technique for efficiently recovering lithium from these dilute solutions containing lithium.

BACKGROUND ART Conventionally, as a method for recovering lithium from a dilute solution containing lithium such as seawater, for example, the aluminum hydroxide coprecipitation method ["Chemical Society of Japan 43rd Annual Meeting, Abstracts RJ, p. 1240 (1981 ), or amorphous aluminum hydroxide [Seawater Magazine, Volume 32, Page 78 (1
978), "Journal of the Japan Mining Association", Volume 99, -; page 585 (+983)), Metal Aluminum [
"Rust Prevention Management," Vol. 1982, p. 369], and an adsorption method using hydrated tin oxide ("Journal of the Japan Mining Association," Vol. 99, p. 933 (+983)) are known.

In addition, methods are being considered to collect lithium salt after evaporating salt lake water or seawater using solar heat, precipitating out salt, etc. (Geological 5urvey Pro
1005, page 79 (1976)).

However, the above-mentioned adsorption methods have the disadvantage that the adsorption capacity and adsorption rate for lithium are small, and the evaporation method that uses solar heat has the disadvantages of requiring a huge area and the same weather conditions, making it difficult to put them into practical use. It is.

In addition, thorium arsenate (rJ, Inorg, Nu
cl, ChelW, J Volume 32, No. 1719
page (+970)), tin antimonate (r)l
ydron+etalurgy J Volume 12, No. 83
Page (+984)) have also been reported to exhibit lithium adsorption properties, but issues such as improvement of adsorption properties and desorption methods remain for practical use.

It has also been reported that various ion sieve type adsorbents exhibit adsorption properties for lithium (rNeor
gan, Mat, J, vol. 9, p. 1041 (1973), same magazine, vol. 12, p. 1415 (1973).
976)), the manufacturing conditions of the adsorbent and its ability to adsorb lithium in natural water have not been clarified, and practical performance has not yet been achieved.

Problems to be Solved by the Invention In order to practically adsorb and recover lithium from dilute solutions such as seawater, geothermal water, and underground brine containing lithium, it is necessary to have excellent selective adsorption for lithium, and to improve the adsorption rate and adsorption rate. having a large capacity and being stable in the dilute solution;
It is necessary to develop an adsorbent that is less toxic and can be repeatedly adsorbed and desorbed.

An object of the present invention is to provide a method for producing a vine adsorbent that satisfies these requirements.

Means for Solving the Problems As a result of various studies, the present inventors found that lithium-containing manganese oxide or lithium-containing manganese hydrate oxide
Recognizing that the lithium eluate obtained by heat treatment at a temperature of 500°C or higher, preferably 550°C or higher, is a lithium adsorbent that can meet the above requirements, we have previously applied for a patent. Application No. 60-011621).

Furthermore, as a result of repeated research on the manufacturing method of lithium-containing manganese compounds, the present inventors found that a method of crushing a lithium compound and a manganese compound, mixing them in an appropriate ratio, and then heat-treating them at a specific temperature is a simple method. It was discovered that an adsorbent with a large adsorption capacity could be prepared, and based on this knowledge, the present invention was completed.

That is, the present invention crushes lithium hydroxide, oxide, carbonate, bicarbonate, nitrate, halide, etc. and manganese hydrated oxide, oxide, carbonate, bicarbonate, nitrate, halide, etc. The present invention provides a method for producing an adsorbent, which is characterized in that, after mixing, the adsorbent is heat-treated at a temperature of at least 100 ml, and the lithium is further eluted with an acid.

The processing of the mixture of the lithium compound and the manganese compound must be carried out at a temperature of 500°C or higher, preferably 700°C or higher, for 10 minutes or more, preferably 30 minutes to 6 hours.

The lithium content of the lithium-containing manganese compound is 0.5
-20%, preferably 1-7%.

The acid used to elute the lithium from the heat-treated lithium-containing manganese compound may be any acidic solution with a pH of 3 or less, but preferably a mineral acid with a pH of 0.05 N or more.

The adsorbent prepared by the method of the present invention selectively adsorbs lithium in seawater and geothermal water, and the lithium concentration in the adsorbent is similar to that of ore.

Effects of the Invention The adsorbent from which lithium is eluted from the lithium-containing manganese compound produced by the method of the present invention has many micropores suitable for lithium adsorption, has excellent selective adsorption for lithium, and has an extremely high adsorption rate and adsorption capacity. Furthermore, it is non-toxic and stable in aqueous solutions, and the lithium concentration in the adsorbent is comparable to that of lithium-containing ores, making it possible to efficiently and economically recover lithium from dilute solutions.

Example Next, the present invention will be explained in detail with reference to Examples.

Example 1 After pulverizing a manganese compound and a lithium compound, they were mixed in the proportions shown in Table 1.
Table sample Manganese compound Lithium compound number
Addition amount (g) Addition amount (g) 1 Dimanganese trioxide 2.3 Lithium carbonate 0.52 Charcoal
Acid〃3.3 Oxidation〃0.23
〃 〃 Hydroxylation 〃0.54
〃 〃 Carbonic acid 〃 〃5 Dioxide 〃
2.5 Oxidation 〃0.26 〃 〃
Hydroxide 〃0.57 〃 〃 Carbonic acid
〃 〃Ta. The mixture was heat treated at a temperature of 800°C for 3 hours. Then 0. After washing with IN hydrochloric acid to elute lithium, the adsorbent was obtained by washing with water and air drying.

0.2 g of each adsorbent obtained has a lithium concentration of 6.6 pp.
After adding each to 100 mL of an aqueous solution (pH 8, 5) of M and stirring at 25°C for 7 days, the lithium concentration in the supernatant was determined to determine the amount of lithium adsorbed. The results are shown in Table 2. The distribution coefficient shown here is the ratio between the equilibrium ion concentration in the aqueous solution and the equilibrium adsorption amount in the adsorbent at the time of adsorption equilibrium, and is expressed by the following equation.

Equilibrium adsorption amount in adsorbent (mg/g) Partition coefficient = □ Equilibrium concentration in aqueous solution (+wg/mL) All adsorbents have excellent lithium adsorption properties, and the lithium adsorption amount is 2 to 3 mg/g. The lithium distribution coefficient is 1
,000 to 10,000, which is clearly superior to conventional aluminum-based adsorbents (partition coefficient: 500) and hydrous tin oxide (partition coefficient: 100).

Table 2 Sample Adsorption amount L1 adsorption rate Partition coefficient number
(mg/g) (X)1 2.65
88.3 3.8 X 1032 2.93
97.8 22. OX l033 2.36
78.7 1.8 x 1034 2.
37 79.0 +, 9 X IQ352.8
5 95.0, 9.5 XIO'6
2.00 66.7 1. OXIO371,50
50,00,5X 103 Example 2 0.05g of each adsorbent obtained in Example 1 was added to 2L of natural seawater, stirred at 25°C for 7 days, and the lithium concentration in the supernatant liquid was determined. was quantified to determine the amount of lithium adsorbed. The results are shown in Table 3. All of these adsorbents are good even in natural seawater systems.Table 3 Sample L1 adsorption amount Adsorption rate L1 concentration factor number
(mg/g) (%)1 2.8
41.2 +, 6 X 10'2 4.
0 58.8 2.4 tt3 2.
8 4+, 2 1.6 tt4 2.
4 35.3 1.4 tt5 4.
0 58.8 2.4 //6 2.
4 35.3 +, 4 tt7 1
．． 2 1? , 7 0.7 sLi adsorption amount (m
g/g) (II reduction coefficient=□)

Claims (1)

[Claims] 1. Lithium is eluted using acid from a lithium-containing manganese compound prepared by pulverizing and mixing a lithium compound and a manganese compound, and then heat-treating the mixture at a temperature of 500°C or higher. A method for producing a lithium adsorbent. 2 Lithium compounds include hydroxide, oxide carbonate,
A method for producing a lithium adsorbent according to claim 1, characterized in that bicarbonate, halide, nitrate, etc. are used. 3 Hydrous oxides, oxide carbonates, as manganese compounds
A method for producing a lithium adsorbent according to claim 1, characterized in that a bicarbonate, a halide, a nitrate, etc. are used. 3. The method for producing a lithium adsorbent according to claim 1, characterized in that an acidic solution with a pH of 3 or less is used as the acid.