JPS6362546A - Composite type lithium adsorbent and its production - Google Patents

Abstract

PURPOSE:To increase selective adsorptivity, adsorbing rate and adsorbing capacity for Li and to enhance the recovering efficiency of Li by eluting Mg from heat-treated composite Mn-Al oxide contg. Mg with acid and preparing an Li adsorbent. CONSTITUTION:Composite Mn-Al compd. contg. Mg is pptd. by mixing a soln. contg. Mg ion and a soln. contg. Mn ion and Al ion and regulating pH to >=10. After heating this composite Mn-Al compd. contg. Mg at >=600 deg.C temp., it is treated with an acid soln. of >=3pH to elute Mg and thereby an Li adsorbent is prepared. In case the proportion of Mn incorporated in composite Al-Mn compd. is small, adsorptivity for Li is small and it is increased according to the increase of the proportion of Mn and attains the maximum in case of 1:1. The obtained adsorbent selectively adsorbs Li from a dilute soln. of seawater and geothermal water.

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 relates to a method for producing a lithium adsorbent that has excellent adsorption properties 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 include lithium-containing ores (lithium content 2-6%) such as subodumene, ambrigonite, betalite, and levidorite.
It is manufactured using raw materials such as salt lakes and underground brine (lithium concentration 50 to 200 ppm), which have high lithium concentrations. .

Currently, the country is completely dependent on imports. -On the other hand, some geothermal water and hot spring water in Japan contain a considerable amount of lithium. There is also a small amount of water surrounding the surrounding ocean.
of lithium (0.17 ppm). Therefore, it is strongly desired to establish a technique for efficiently recovering lithium from these dilute solutions containing lithium.

Conventional technology 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 IJ, p. 1240 (+981) ) - or should be regular shaped aluminum hydroxide [") M Hyozume", Vol. 32, page 78 (1978), r Journal of the Japan Mining Association, Vol. 99, No. 58
5 pages (+983)), metal aluminum ["Rust Prevention Management", Vol. 1982, p. 369], hydrous tin oxide ["Journal of the Japan Mining Association", Vol. 99, p. 933].

In addition, methods are being considered to collect lithium salt after evaporating salt lake water or 7m water using solar heat, precipitating out salt, etc. (Geological 5urvey Pro
1005, page 79 (1976)).

However, the adsorption method described above has the drawback that the adsorption capacity and adsorption rate for lithium is small, and the evaporation method that uses solar heat has the drawback that it requires a huge area and the same weather conditions, making it difficult to put them into practical use. It is. In addition, thorium arsenate (rJ, lnorg, Nuc
L, ChelW, J Volume 32, Page 1719 (
+970)), tin antimonate (rllydrom
etallurgy J Vol. 12, p. 83 (1ri84)) have also been reported to exhibit lithium adsorption properties, but there are still issues to be solved in order to put them into practical use, such as improving adsorption properties and de@ has been done.

In addition, it has been reported that various ion sieve type adsorbents exhibit adsorption properties for lithium (rNeor
Gan, At, J, Volume 9, Page 1041 It has not been clearly demonstrated that it is rejuvenating, and it has not yet reached practical performance.

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. It is necessary to develop an adsorbent that has a large capacity, is stable in the dilute solution α, has low toxicity, and is capable of repeated adsorption and desorption.

An object of the present invention is to provide a method for producing a breath absorbent that can satisfy these requirements.

Means for Solving the Problems As a result of repeated research on the synthesis of various adsorbents, the inventors of the present invention have developed a lithium adsorbent by heat-treating a manganese-aluminum composite compound containing magnesium and then acid-treating it. Recognizing this fact, we have come up with the present invention. ! Manganese-aluminum composite compound containing magnesium% The adsorbent made by yA, which is heated at a temperature of 600°C or higher and treated with an acid solution at pH 3 or lower to elute magnesium, has excellent lithium selective adsorption properties. showed that.

The magnesium-containing manganese-aluminum composite compound used in the present invention can be prepared by a specific method. It is possible to use products prepared by various methods, rather than products made by a manufacturer.

For example, by mixing a solution containing magnesium ions, a solution containing manganese ions, and aluminum ions, the pH
A coprecipitation method in which the magnesium oxide is adjusted to 10 or more and coprecipitated, an adsorption method in which manganese oxide such as manganese oxide and a 75-luminium compound CZ such as aluminum hydroxide are added to a solution containing magnesium ions to adsorb magnesium, and magnesium hydroxide. A method such as mixing by mixing a magnesium compound such as hydroxide, manganese oxide, aluminum hydroxide, etc. in a fixed ratio can be used.

When the proportion of manganese in the aluminum-manganese composite compound is small, the lithium adsorption is low, but as the proportion of manganese increases, the lithium adsorption increases, reaching a maximum at 1:l, and conversely decreases as the proportion increases further. It was recognized that there were multiple effects.

The heat treatment temperature of the magnesium-containing manganese-aluminum composite compound needs to be 600°C or higher, preferably 750°C or higher.

The crystallization reaction rapidly progresses with heating, but at least 1
0 minutes or more is required, and desirably 1 hour or more is required.

Elution of magnesium from the heat-treated product can be achieved by treating it with a weak acid solution having a pH of 3 or more for several hours or more, preferably for one day or more. The acid used for elution is p.
Any acidic solution of H3 or less may be sufficient, but preferably hydrochloric acid,
Mineral acids such as sulfuric acid, nitric acid, and phosphoric acid are good.

The adsorbent produced by the method of the present invention selectively adsorbs lithium from dilute solutions such as seawater and geothermal water, and the adsorbent produced from the magnesium-containing manganese oxide prepared by the method of the present invention has micropores. It has a large amount of lithium, has excellent regressive adsorption properties for lithium, has an extremely high adsorption rate and adsorption capacity, is non-toxic, is stable in aqueous solution, has a lithium concentration in the adsorbent that is similar to ore, and is manufactured using a powder method. By using an adsorbent, the lithium can be recovered from dilute iiiα very efficiently and economically. In these adsorbents doped with magnesium, although the ionic radii of magnesium ions and lithium ions are almost equal, hydration energy of magnesium is larger, and therefore lithium is thought to be selectively adsorbed.

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

Machikata TP Guri 1 2.20 g of manganese hydroxide oxide, 1.96 g of aluminum hydroxide, and 1.46 g of magnesium hydroxide were pulverized and mixed, and then heat-treated at a predetermined temperature of 550-1150°C for 1 hour. This heating product IgltO, IN hydrochloric acid 5
001 for 10 days to elute magnesium, then washed with water and air-dried to prepare an adsorbent.

30 mg of the adsorbent thus obtained was dissolved in lithium chloride water (lithium concentration 6.2 ppm, p 148.5
) After stirring for 7 days, the lithium concentration in each frozen solution was determined and the amount of lithium adsorbed was calculated. 5
Table 1 shows the results of measuring the amount of adsorption for adsorbents prepared at various temperatures from 50 to 1150°C. The amount of lithium adsorbed by these adsorbents increases as the heating temperature increases, and 8
It became almost constant between 50 and 1050°C, and the lithium adsorption rate reached 99% and the distribution coefficient 'F18.5XIO'. Furthermore, it was observed that the adsorbent prepared by heating at a higher temperature of 1150° C. had a tendency to have a lower adsorption performance. Note that the distribution coefficient here is the ratio of the equilibrium metal ion concentration in the solution to the metal ion concentration adsorbed on the adsorbent, and is expressed by the following equation.

21 Seki1 +1 Table 1 Heating temperature and lithium adsorption property 2 Jj In Example 1: 50 mg of the adsorbent was added to 2-1' L of natural 1a water and stirred for 7 days, 1. As a result of quantifying the lithium concentration in the clear liquid and calculating the lithium adsorption amount, as shown in Table 2, the lithium absorption rate was 65% at the maximum, and the adsorption amount was 4.4 mg/g. is sea level 2 i1m
It is clear that the adsorbent from Zero is an excellent lithium adsorbent as it shows great adsorption ability for lithium in water and stray lithium.

Example 3 Manganese hydroxide oxide, aluminum hydroxide and monomagnesium hydroxide were mixed and pulverized at 950°C.
Heat treated for hours. 0.0 g of each product. IN
Magnesium was eluted by immersion in 500 ml of aqueous hydrochloric acid solution for 1 day, followed by washing with water and air drying to prepare various adsorbents. 30 mg of each of these adsorbents was added to 25 m of lithium chloride solution (lithium concentration 6.2 ppm, pH 8.5).
After stirring for 7 days, the lithium concentration in the upper Pt solution was determined to calculate the lithium adsorption ffi. As a result, as shown in Table 3, both the adsorbents with zero deviation showed high lithium adsorption properties. Especially Riko N.

It is clear that the adsorbent b1 of the present invention has excellent lithium adsorption properties, with the mixing ratio (molar ratio) of 1:17 being 1:1:t<excellent lithium adsorption properties.

Table 3 Example 4 50 mg of the adsorbent prepared in Example 4 was added to 2 L of seawater.
After stirring for 7 days,
The lithium adsorption amount was determined by determining the J thium concentration.

As shown in Table 4, it is clear that lithium is adsorbed from seawater as well. Special ζko Mn: Al force S1
:1 Those in Table 4 showed the most worrying adsorption properties.

As shown in No. 20, the adsorbent produced by the method of the present invention exhibits excellent lithium adsorption properties, and it is clear that the method of the present invention is superior.

Patent applicant: Director of the Agency of Industrial Science and Technology Yukio Iizuka Designated agent: Director of the Shikoku Industrial Technology IFI Testing Center, the Agency of Industrial Science and Technology Hajime Tsubaki
Kazuhiko

Claims (1)

[Scope of Claims] 1. A lithium adsorbent prepared by eluting magnesium from a heat-treated manganese-aluminum composite oxide containing magnesium with an acid. 2. A method for producing a lithium adsorbent, which comprises heating a manganese-aluminum composite oxide containing magnesium at a temperature of 600° C. or higher and then treating it with an acid to elute the magnesium. 3 The pH of the acid used to elute lithium is
Claim 2, characterized in that the solution is 3 or less.
A method for producing a lithium adsorbent as described in Section 1.