JP2850309B2 - Method for producing lithium adsorbent - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a lithium adsorbent, and particularly to a method for producing a lithium adsorbent, which is excellent in selective adsorption to lithium, has a large adsorption capacity and a large adsorption speed, and has a low lithium concentration. The present invention relates to a method for producing an inexpensive lithium adsorbent which is stable in a solution and has low toxicity.

[Prior Art] In recent years, lithium metal and its compounds have been used in a wide range of fields such as ceramics, batteries, absorption type refrigerants, pharmaceuticals, etc. In the future, large capacity batteries, aluminum alloy materials, fusion fuels, etc. The demand for lithium is expected to increase further in the future. (Journal of the Japan Mining Association, Vol. 97, p. 221).

Lithium metal and its compounds are produced mainly from lithium-containing ores (lithium content 2 to 6%) such as spodumene, ambrigonitite, petalite, levitrite, etc., or salt lakes with high lithium concentration or underground brine ( Lithium concentration of 50 to 200 ppm) is collected by evaporation method.

In Japan, lithium-containing ores as described above are scarce, and a method for recovering from lithium-containing liquid has not been established. Therefore, the fact is that lithium metal and its compounds all depend on imports. On the other hand, some geothermal and hot spring waters in Japan contain considerable amounts of lithium, and the surrounding ocean also contains trace amounts of lithium (0.17 ppm). Therefore, it is strongly desired to establish a technique for efficiently rotating lithium from a dilute solution containing lithium.

As a part of the technology for recovering lithium from a dilute solution containing lithium, various lithium adsorbents have been proposed (for example, JP-A-61-171535, JP-A-61-278347, and 61-283).
Nos. 341 and 63-80844). According to these, after heating a lithium manganese compound or a manganese compound or a lithium-containing manganese oxide or lithium oxide at a predetermined temperature, an excellent lithium adsorbent can be obtained by eluting the lithium into an acid. It has been shown.

[Problems to be Solved by the Invention] In order to practically adsorb lithium from a dilute solution containing lithium, a selective adsorption property to lithium is excellent, an adsorption speed and an adsorption capacity are large, and the lithium is stable in a dilute solution. It has low toxicity and can be repeatedly adsorbed and desorbed. Further, considering the economic aspect, it is necessary to develop a lithium adsorbent that can be obtained at a high synthesis rate. When the above technology is examined from such a viewpoint, unreacted substances still remain in the lithium adsorbent, and this unreacted substance causes a decrease in lithium adsorptivity. desired.

The present invention has been made to solve such technical problems, and an object of the present invention is to reduce the residual amount of unreacted substances that cause a decrease in lithium adsorptivity as much as possible, and to further enhance the adsorption performance. It is to provide a method for manufacturing the.

[Means for Solving the Problems] The present invention, which has achieved the above-mentioned object, refers to a method in which a lithium compound and a manganese compound are pulverized and mixed, and then granulated.
This is a method for producing a lithium adsorbent having a feature in that lithium is eluted from a lithium-containing manganese compound synthesized by heat treatment at a temperature of 0 ° C. or higher using an acid.

[Action] The present inventors have studied from various angles a means for reducing unreacted substances in the lithium adsorbent as much as possible. As a result, prior to the heat treatment after the lithium compound and the manganese compound are pulverized and mixed (the order of pulverization and mixing does not matter; the same applies hereinafter), if the mixture is granulated prior to the heat treatment, It has been found that the amount of the remaining substance can be reduced, and a lithium adsorbent having more excellent adsorption performance can be obtained.
Here, the present invention has been completed. That is, according to the study of the present inventors, by performing granulation with a binder or the like prior to heat treatment, the adhesion between the lithium compound and the manganese compound can be improved, thereby increasing the reactivity during the heat treatment. It increased the amount of unreacted substances.

The reason why such an effect is obtained can be considered as follows. That is, the reaction between the lithium compound and the manganese compound proceeds according to the following formula (I) or (II). It is considered that these reactions are promoted by improving the adhesion between the two.

Examples of the lithium compound used in the present invention include hydroxides, oxides, carbonates, bicarbonates, halides, and nitrates of lithium. One or more of these may be used in an appropriate combination. . The manganese compound used in the present invention includes a manganese hydrate [Mn
OOH, Mn (OH) ₂ etc.], oxides, carbonates, bicarbonates, halides, nitrates and the like, and one or more of these may be used in an appropriate combination.

After pulverizing and mixing the above lithium compound and manganese compound at an appropriate ratio, kneading with an appropriate solvent,
Preferably, granulation is performed to a particle size of 0.5 to 2 mm. The mixing ratio of the lithium compound and the manganese compound is not particularly limited, but it is appropriate to mix them so that the ratio of the number of moles of lithium to the number of moles of manganese is 0.1 to 1.0, preferably about 0.5 to 1.0. As a solvent used for kneading, granulation is possible with water alone, but it is preferable to use a binder. Examples of such a binder include:
Examples include, but are not limited to, synthetic polymers such as polyvinyl alcohol and polyvinyl chloride, and natural polymers such as cellulose and lignin. On the other hand, the means for granulation is not particularly limited as long as granulation is carried out using various conventionally known granulators.However, granulation having a uniform particle size can be obtained. The use of a dynamic or extruder granulator is recommended.

The adsorbent of the present invention is obtained by eluting lithium using an acid from a lithium-containing manganese compound synthesized by heat-treating the above-mentioned granulated material at a temperature of 350 ° C or higher, preferably 400 ° C or higher. At this time, the heat treatment temperature needs to be 350 ° C. or higher as described above. This is 350 ° C
If the heat treatment is performed at a temperature lower than the above, the reaction between the lithium compound and the manganese compound does not sufficiently proceed, and the adsorption performance of the obtained adsorbent is significantly reduced. The heat treatment time is appropriately from 5 minutes to 10 hours, preferably from about 30 minutes to 6 hours. The acid used for eluting lithium from the lithium-containing manganese compound may be an acidic solution having a pH of 3 or less, and preferably a mineral acid of 0.05 M or more.

Hereinafter, the present invention will be described in more detail with reference to Examples.
The following examples are not intended to limit the present invention, and any change in the design in the spirit of the above and below is included in the technical scope of the present invention.

[Example] Lithium carbonate (Li ₂ CO ₃ ) and manganese oxide hydroxide (MnOO)
H) is crushed and mixed so that the Li / Mn molar ratio becomes 0.6, and then granulated with a particle size of 0.5 to 2 mm using a tumbling granulator using a 1% aqueous solution of polyvinyl alcohol (PVA2000) as a binder. Was manufactured. Thereafter, the granulated product was subjected to a heat treatment under the conditions shown in Table 1.

When the synthesis rate of LiMn ₂ O _{4 in} the sample was investigated for the above heat treatment, the results shown in FIG. 1 were obtained. FIG. 1 also shows, as a comparative example, the synthesis rate in the case where the powdery material was subjected to heat treatment without granulation. In each case, the synthesis rate was determined by gas analysis of the sample to obtain unreacted Li ₂ CO ₃ , and using this value and Li ₂ CO ₃ in the mixed raw material.

As is clear from FIG. 1, the sample granulated at any temperature has a synthesis rate of 20% as compared with the sample not granulated.
It is recognized that the number has increased.

Next, the sample heated at 400 ° C. (Sample No. 2)
After washing with 0.2N-HC1 to elute lithium, the mixture was air-dried to obtain a lithium adsorbent. On the other hand, the above sample was crushed in a mortar (sample No. 2 '), and 400 ° C without granulation.
For 4 hours (sample No. 7), lithium was eluted with an acid in the same manner as above to obtain a lithium adsorbent. 1 g of each of these adsorbents was simulated with brine ([Li] = 13
(0 ppm), immersed in 250 ml and allowed to stand at room temperature for 7 days, and then the amount of lithium in the adsorbent was quantified to determine the amount of lithium adsorbed.
Table 2 shows the results.

It is clear from Table 2 that the adsorbent obtained by pulverizing the sample obtained by granulation has an adsorption amount improved by 10% or more than the adsorbent manufactured without granulation. I understand well.

[Effect of the Invention] As described above, according to the present invention, by granulating the raw material before the heat treatment, the degree of contact between the lithium compound and the manganese compound can be increased, and the reactivity can be improved. A lithium adsorbent with excellent performance was realized.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the heating temperature and the LiMn ₂ O ₄ synthesis rate.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor ▲ Mio Sakakihara 2-3-3 Hananomiyacho, Takamatsu City, Kagawa Prefecture Inside the Industrial Technology Research Institute, Shikoku (72) Inventor Toshinobu Nishimura Kobe, Hyogo Prefecture 2-3-1 Shinohara Amo Noyama-cho, Nada-ku (72) Inventor Mamoru Onoda 1-1-4-8, Midorigaoka-cho, Miki City, Hyogo Prefecture (72) Inventor Junji Kumamoto 2-10-E 6706 Kita-Aoki, Higashinada-ku, Kobe City, Hyogo Prefecture (72) Inventor Yoshifumi Kameoka 7-3-3-334 Takamaru, Tarumi-ku, Kobe-shi, Hyogo (56) References JP-A-61-283341 (JP, A) JP-A-62-83035 (JP, A) (58) ) Field surveyed (Int. Cl. ⁶ , DB name) B01J 20/04 C01G 45/00

Claims (4)

(57) [Claims] A lithium compound and a manganese compound are crushed.
A method for producing a lithium adsorbent, comprising mixing and granulating the mixture, and heat-treating the granulated product at a temperature of 350 ° C. or more to elute lithium from the lithium-containing manganese compound using an acid. 2. The method according to claim 1, wherein the lithium compound is one or more selected from the group consisting of hydroxides, oxides, carbonates, bicarbonates, halides and nitrates. Manufacturing method. 3. The method according to claim 1, wherein the manganese compound is at least one selected from the group consisting of hydrated oxides, oxides, carbonates, bicarbonates, halides and nitrates. The production method according to 2). 4. The method according to claim 1, wherein an acidic solution having a pH of 3 or less is used as the acid.