JPH0232218B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a novel manganese compound and a method for producing the same. More specifically, the present invention provides a novel manganese compound that has excellent selective adsorption properties for lithium, has an extremely high adsorption rate and adsorption capacity, is suitable as a lithium adsorption material, and is also useful as a battery active electrode material. The present invention relates to a manufacturing method thereof. BACKGROUND OF THE INVENTION Manganese oxides are known to have various crystal forms, and exist naturally as manganese ore, nastite, and the like. This manganese oxide is generally used as an active cathode material in electrochemical cells such as dry batteries and batteries.A typical battery includes, for example, a manganese oxide cathode, a zinc anode, and an aqueous electrolyte solution (ammonium chloride and zinc chloride). An aqueous solution containing Conventionally, such manganese oxide for batteries has generally been prepared by an electrolytic method, but recently a method of preparing it from LiMn ₂ O ₄ has been proposed (Japanese Patent Publication No. 1983-
Publication No. 34414). Manganese oxide prepared from this LiMn ₂ O ₄ has electrochemical activity and is said to be effective not only in aqueous electrolytes but also in non-aqueous electrolytes. The LiMn ₂ O ₄ has a spinel structure, and is made by mixing lithium carbonate and manganese oxide in a ratio such that the atomic ratio of manganese and lithium is 2:1,
By heat treatment at a temperature in the range of 800 to 900℃, or by heating a mixture of an appropriate combination of lithium salts/oxides such as lithium hydroxide and manganese carbonate and manganese salts/oxides at a temperature in the range of 500 to 900℃. Obtained by heat treatment at a certain temperature. By the way, manganese compounds prepared from manganese oxide containing lithium have recently been recognized as being excellent as lithium adsorbents [Kagaku Kogyo, p. 686 (1985)], and have been used as adsorbents for extracting lithium from dilute solutions. is expected to be applied.
For example, the manganese compound obtained by acid-treating LiMn ₂ O ₄ has almost the same X-ray diffraction characteristics as LiMn ₂ O ₄ and has excellent selective adsorption of lithium in seawater, with an equilibrium adsorption amount of lithium of 8.5 mg/ The Li ₂ O content is 1.8%, which is about half that of lithium ore. As described above, manganese compounds prepared from manganese oxide containing lithium are useful as lithium adsorption materials and battery active electrode materials, but they are expensive because they use expensive lithium as a raw material. There is a problem that cannot be avoided. Problems to be Solved by the Invention An object of the present invention is to provide a novel manganese compound that is useful as a lithium adsorption material, a battery active electrode material, etc., and is inexpensive to produce. Means for Solving the Problems The present inventors previously prepared a compound using magnesium, which has a slightly smaller ionic radius than lithium.
By treating MgMn ₂ O ₄ with acid, we succeeded in obtaining a new magnesium compound that showed clearly different X-ray diffraction properties from those obtained from LiMn ₂ O ₄ but also had similar physical properties. As a result of further research, it was discovered that another new manganese compound could be obtained by using Mg ₂ MnO ₄ as a raw material and treating it with acid.Based on this knowledge, the present invention was made. Ivy. That is, the present invention consists of an acid-treated product of Mg ₂ MnO ₄ , and the relative intensity of the main X-ray diffraction peak is as follows: Interplanar spacing (Å) Relative intensity (CuKα ray irradiation) 4.75±0.03 Strong 2.92±0.03 Weak 2.49±0.03 The present invention provides a manganese compound having a strength of 2.38±0.03, a strength of 2.06±0.03, a strength of 1.59±0.03, a medium strength of 1.46±0.03. This is an acid-treated product of LiMn ₂ O ₄ and
A novel compound that exhibits X-ray diffraction characteristics clearly different from that of acid-treated MgMn ₂ O ₄ ,
It can be produced by treating Mg ₂ MnO ₄ with an acidic solution having a pH of 5 or lower and eluting the magnesium therein. Used as a raw material in the present invention
Mg ₂ MnO ₄ can be produced, for example, by mixing MgO and MnO ₂ at a molar ratio of 2:1 and heat-treating the mixture at a temperature of 800°C for several days [Rev.Chem. Mineral)” Volume 1,
page 175 (1964)] or magnesium hydroxides, oxides, carbonates, bicarbonates, nitrates,
Manufactured by mixing a halide, etc. with a hydrous oxide, oxide, carbonate, bicarbonate, nitrate, halide, etc. of manganese in an appropriate combination, and then heating the mixture at a temperature of 400°C or higher. Can be done. This Mg ₂ MnO ₄ is prepared by adding one or more mineral acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, and one or more organic acids such as formic acid and acetic acid, and adjusting the pH to 5 or less, preferably in the range of 1 to 3. The target manganese is obtained by immersing the solid in an acidic solution and stirring at room temperature for at least 1 hour, preferably for several days to elute and remove the magnesium. A compound is obtained. The X-ray diffraction characteristics of this manganese compound are shown below. ASTM card Mg ₂ MnO ₄ and
Manganese compound prepared from LiMn ₂ O ₄ (Tokuko Sho
58-34414) is also shown.

[Table] Thus, the manganese compound of the present invention
Obviously different from the manganese compound from LiMn ₂ O ₄ and almost similar to the starting material Mg ₂ MnO ₄
It shows line diffraction characteristics. The difference between the X-ray diffraction characteristics of this manganese compound and the raw material Mg ₂ MnO ₄ is that the lattice shrinks when a new form of manganese is formed, and a slight change in the peak position is observed. In addition, the manganese compound of the present invention has a lattice spacing of 1.46 Å.
This compound shows a diffraction peak at 2.92 Å and has a fine structure different from that of manganese oxide prepared from LiMn ₂ O ₄ . Furthermore, as a result of chemical analysis, the manganese compound of the present invention has a magnesium content of 10% by weight or less, and the theoretical magnesium content of the raw material Mg ₂ MnO ₄
29.0% by weight, it is recognized as a completely new substance with a different composition from Mg ₂ MnO ₄ . Effects of the Invention The manganese compound of the present invention has a layer spacing suitable for lithium adsorption, has excellent selective adsorption for lithium, has an extremely high adsorption rate and adsorption capacity, is non-toxic, and is stable in an aqueous solution. The lithium concentration in the adsorbent is comparable to that of lithium-containing ores, and the lithium can be efficiently and economically recovered from dilute solutions, such as seawater or geothermal water. The manganese compounds are also useful as battery active electrode materials. Examples Next, the present invention will be explained in detail by examples. Example 1 While stirring a mixed solution of 200ml of 1M magnesium chloride aqueous solution and 100ml of 1M manganese chloride aqueous solution, add ammonia water (1:
1) was added, and then 100 ml of 30% hydrogen peroxide solution was added. After aging the product in the mother liquor for 3 days, it was filtered and washed several times with aqueous ammonia at pH 10.5. The atomic ratio of magnesium and manganese content in the product was 2:1. This was heat-treated at 800° C. for 1 hour to prepare Mg ₂ MnO ₄ . 1 g of this heated product was added to 0.5N hydrochloric acid solution 1 and stirred for 30 days, and then the product was filtered, washed, and dried at 70°C to prepare a manganese compound. Table 1 shows the X-ray diffraction characteristics of the heated product and manganese compound obtained. For comparison, ASTM card
19-773 shows the X-ray diffraction characteristics of Mg ₂ MnO ₄ .

[Table] The X-ray diffraction characteristics of Mg ₂ MnO ₄ prepared in the examples were in excellent agreement with those described in the ASTM card. Furthermore, although the manganese compound prepared by acid-treating Mg ₂ MnO ₄ of the present invention has a slightly smaller interplanar spacing compared to Mg ₂ MnO ₄ , it is clear that it maintains its original structure. It is. Table 2 shows the chemical analysis values of these manganese compounds.

[Table] The chemical analysis values of Mg ₂ MnO ₄ prepared in this experiment almost agreed with the theoretical values. The manganese compound of the present invention is
It is a new compound with a significantly lower magnesium content than Mg ₂ MnO ₄ and a different composition. Example 2 While stirring a mixed solution of 200 ml of 1M aqueous magnesium chloride solution and 100 ml of 1M aqueous manganese chloride solution, aqueous ammonia (1:1) was added until the pH reached 10.5, and then 100 ml of 30% hydrogen peroxide solution was added. After aging the product in the mother liquor for 3 days, it was filtered and washed several times with aqueous ammonia at pH 10.5. The atomic ratio of magnesium and manganese content in the product was 2:1. This was heat-treated at 500° C. for 1 hour to prepare Mg ₂ MnO ₄ . 1g of this heat-treated product
was added to 0.1M nitric acid solution 1, stirred for 5 days, and the product was filtered, washed, and dried. The X-ray diffraction properties of the product are shown in Table 3. Although slight shrinkage was observed in the obtained manganese compound as in Example 1, it is clear that it has a structure similar to Mg ₂ MnO ₄ . The chemical analysis results of these compounds are shown in Table 4.

【table】

【table】

[Table] It is clear that the magnesium compound of the present invention is a novel compound with a composition different from Mg ₂ MnO ₄ . Example 3 The lithium adsorption properties of the manganese compounds prepared in Examples 1 and 2 in seawater were investigated. That is, 50 mg of a manganese compound was added to seawater 2 and stirred for 7 days. The lithium concentration in seawater before and after adsorption was determined by atomic absorption spectrometry to determine the amount of lithium adsorbed. The results are shown in Table 5. From these results, it is clear that the manganese compound of the present invention concentrates lithium in seawater approximately 40,000 times, and has excellent lithium adsorption properties.

【table】

Claims (1)

[Scope of Claims] 1. A manganese compound which is an acid-treated product of Mg ₂ MnO ₄ and has the following relative intensity of the X-ray diffraction peak. Planar spacing (Å) Relative intensity (CuKα irradiation) 4.75±0.03 Strong 2.92±0.03 Weak 2.49±0.03 Strong 2.38±0.03 Weak 2.06±0.03 Strong 1.59±0.03 Medium 1.46±0.03 Medium 2 Mg ₂ MnO ₄ acidified with PH5 or less treated with a solution;
A method for producing a manganese compound having the following relative intensity of an X-ray diffraction peak, the method comprising eluting magnesium therein. Plane spacing (Å) Relative intensity (CuKα irradiation) 4.75±0.03 strong 2.92±0.03 weak 2.49±0.03 strong 2.38±0.03 weak 2.06±0.03 strong 1.59±0.03 medium 1.46±0.03 medium 3 Acidic solutions with PH5 or less are mineral acids and The method according to claim 2, which contains at least one selected from organic acids.