KR101179505B1 - Preparation of Lithium Hydroxide Monohydrate from Lithium Carbonate - Google Patents

Abstract

The present invention comprises one step of dissolving lithium carbonate in water to obtain a lithium carbonate aqueous solution; Mixing the aqueous hydrogen peroxide solution with the aqueous lithium carbonate solution; Evaporating the mixed solution to prepare lithium peroxide powder; And it relates to a method for producing lithium hydroxide first hydrate comprising the four steps of producing lithium hydroxide monohydrate by adding water to the lithium peroxide powder and then evaporated. According to the present invention, a method for preparing lithium hydroxide monohydrate from a lithium waste aqueous solution containing lithium carbonate can be easily prepared without using a conventional organic solvent, using a specific apparatus such as a high pressure reactor, a solvent, or decomposition by carbon dioxide. Lithium bromide, which is rapidly increasing as a refrigerant absorber of an absorption type air conditioner, expensive lithium chloride, which is increasing in demand as an absorbent of a dehumidifying device, and lithium carbonate used as a cathode active compound of a lithium secondary battery. It is expected to be used as a raw material for the production of.

Description

Preparation method of lithium hydroxide monohydrate from lithium carbonate {Preparation of Lithium Hydroxide Monohydrate from Lithium Carbonate}

The present invention relates to a method for producing lithium hydroxide monohydrate from lithium carbonate.

Lithium hydroxide is used in the form of monohydrate or anhydride and is used for gas and air purification, heat transfer media, polymerization catalysts, production of advanced grease stearate that can perform well in extreme temperatures, carbon dioxide absorbers in submarines and spacecraft, and organic synthesis. It is used as a raw material of a catalyst (polymerization initiator) and another lithium compound. Currently, 80 to 90 kinds of lithium compounds are industrially produced, and lithium compounds used as main raw materials in the manufacturing process of lithium compounds are lithium carbonate and lithium hydroxide. High purity lithium hydroxide is most commonly used as a carbon dioxide scavenger except that it is used to prepare polymerization initiators and greases.

The process of converting lithium hydroxide, used as a carbon dioxide scavenger for submarines and spacecraft, to lithium carbonate is: Carbon dioxide (CO ₂ ) from human breathing in submarines and space is absorbed by lithium hydroxide and other gaseous components are circulated. Chemical absorption of carbon dioxide by lithium hydroxide occurs through a two-step reaction as follows. Lithium hydroxide monohydrate is produced by the exothermic reaction as in Scheme 1 below.

[Reaction Scheme 1]

Lithium carbonate is produced by the endothermic reaction of carbon dioxide and lithium hydroxide monohydrate as shown in Scheme 2 below.

Scheme 2

The production of lithium carbonate by the reaction of lithium hydroxide and carbon dioxide can be represented by the following scheme 3.

Scheme 3

As in Scheme 3, lithium hydroxide monohydrate is converted to lithium carbonate and finally discarded.

Many techniques are known for recovering high purity lithium carbonate from lithium carbonate converted from lithium hydroxide monohydrate or lower lithium carbonate generated during the recycling of spent secondary batteries. (Japanese Patent Laid-Open No. 59-83930, Japanese Patent Laid-Open 61-83) 251511, etc.)

In addition, Korean Patent No. 10-0725589 discloses a method for producing lithium hydroxide first hydrate from lithium carbonate. The above technique can produce a high purity lithium hydroxide monohydrate by reacting lithium carbonate with an alkali hydroxide compound to form a carbonate precipitate and then evaporating and recovering an aqueous lithium solution, but if the removal of precipitated carbonate is incomplete, lithium hydroxide There was a problem of lowering the purity and a need for a separate evaporation process for the recovery of lithium hydroxide.

The present invention is an improvement over the Korean Patent No. 10-0725589, and an object thereof is to provide a method for producing lithium hydroxide from lithium carbonate through a simpler process.

In order to achieve the above object, the present invention is one step of obtaining a lithium carbonate aqueous solution by dissolving lithium carbonate in water; Mixing the aqueous hydrogen peroxide (H ₂ O ₂ ) solution with the aqueous lithium carbonate solution; Evaporating the mixed solution to prepare lithium peroxide (Li ₂ O ₂ ) powder; And it provides a method for producing lithium hydroxide monohydrate from lithium carbonate comprising the four steps of adding water to the lithium peroxide powder and then evaporating to produce lithium hydroxide monohydrate (LiOH? H ₂ O).

According to the present invention, a method for preparing lithium hydroxide monohydrate from a lithium waste aqueous solution containing lithium carbonate can be easily prepared without using a conventional organic solvent, using a specific apparatus such as a high pressure reactor, a solvent, or decomposition by carbon dioxide. Lithium bromide, which is rapidly increasing as a refrigerant absorber of an absorption type air conditioner, expensive lithium chloride, which is increasing in demand as an absorbent of a dehumidifying device, and lithium carbonate used as a cathode active compound of a lithium secondary battery. It is expected to be used as a raw material for the production of.

1 is a simplified process diagram of the manufacturing method.
2 is an X-ray diffraction curve of lithium carbonate used in the preparation of the present invention.
3 is an X-ray diffraction curve of lithium oxide prepared in Example 1. FIG.
4 is an X-ray diffraction curve of the lithium hydroxide monohydrate prepared in Example 1. FIG.
5 is an X-ray diffraction curve of the compound prepared in Example 2. FIG.
6 is an X-ray diffraction curve of the compound prepared in Example 3. FIG.
7 is an X-ray diffraction curve of the compound prepared in Example 4. FIG.

The present invention comprises one step of dissolving lithium carbonate in water to obtain a lithium carbonate aqueous solution; Mixing the aqueous hydrogen peroxide solution with the aqueous lithium carbonate solution; Evaporating the mixed solution to prepare lithium peroxide powder; And it relates to a method for producing lithium hydroxide first hydrate comprising the four steps of producing lithium hydroxide monohydrate by adding water to the lithium peroxide powder and then evaporated. At this time, it is preferable to maintain the temperature in the range of 20 ℃ to 120 ℃ in all the above steps. If the temperature is maintained below 20 ℃, the evaporation time, the reaction time is very long due to the very slow reaction rate of hydrogen peroxide and lithium carbonate, and if the reaction temperature rises above 120 ℃ in the reactor due to violent reaction Bubbles and sudden gas generation are feared. More preferably, it is the range of 100 to 120 degreeC. Figure 1 is a simplified process diagram showing a method for producing lithium hydroxide monohydrate from lithium carbonate, the present invention will be described in detail for each step.

The first step is a step of dissolving lithium carbonate in water to obtain a lithium carbonate aqueous solution. The amount of lithium carbonate dissolved in water depends on solubility. The solubility of lithium carbonate in water is 1.54 g / 100 g H ₂ O (0 ° C), 1.17 g / 100 g H ₂ O (40 ° C), 0.72 g / 100 g H ₂ O (100 ° C.). Considering the thermodynamic properties of lithium carbonate and water mixtures, the maximum amount of lithium carbonate that can be dissolved in water is 0.72 g to 1.54 g for 100 g of water. In the present invention, the mass ratio of lithium carbonate and water is preferably maintained at 0.5 to 1.5: 100. If the mass ratio of lithium carbonate and water is 0.5: 100 or less, there may be a problem in that the amount of recovered lithium hydroxide monohydrate is very small.When the ratio is 1.5: 100 or more, the reaction runaway phenomenon and precipitation of insoluble lithium carbonate are caused by rapid reaction with hydrogen peroxide. This can be accompanied.

The second step is a step of mixing the hydrogen peroxide aqueous solution to the lithium carbonate aqueous solution. It is preferable that the mass ratio of the aqueous hydrogen peroxide solution and the aqueous lithium carbonate solution is maintained at 1: 1 to 150. Due to the vigorous reactivity of hydrogen peroxide, the mass ratio of lithium carbonate and hydrogen peroxide must be very tightly controlled in this range. More preferred mass ratio is in the range of 1: 2 to 10. The reaction between hydrogen peroxide and lithium carbonate is preferably completed within 1 hour, resulting in a transparent aqueous lithium hydroxide solution.

The third step is to prepare a lithium peroxide powder by evaporating the mixed solution. The pressure for evaporation is adjusted in the range of 0.01 to 1 atm. The pressure is closely related to the rate of evaporation of water from the hydrogen peroxide solution and determines the rate of reaction with lithium carbonate. Pressures below 0.01 atm sharply increase the hydrogen peroxide concentration, causing intense foaming and temperature rise due to heat of reaction. On the other hand, a pressure exceeding 1 atm induces a mild reaction condition of lithium carbonate and hydrogen peroxide, but has a disadvantage in that the reaction time and evaporation time are longer. More preferred pressure is 0.05 to 0.3 atm.

Step 4 is a step of preparing lithium hydroxide monohydrate by adding water to the lithium peroxide powder and then evaporating. The mass ratio of lithium peroxide and water to be added is preferably in the range of 1: 5 to 50. More preferred mass ratio is in the range of 1:10 to 20. The reaction of lithium peroxide with water is completed in less than an hour, producing white lithium hydroxide monohydrate. In the above process, the pressure is preferably adjusted to 0.01 ~ 1 atm range. More preferred pressure range is 0.01 to 0.05 atm.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are only to illustrate the present invention, and it should be understood that the present invention is not limited thereto.

Example  One

About 1.2 g of lithium carbonate was dissolved in 100 g of distilled water in a reactor at 110 ° C. At this time, lithium carbonate was used as lithium carbonate analyzed by the X-ray diffraction curve of FIG. The aqueous solution was stirred for 1 hour and 220 g of hydrogen peroxide solution was added to the completely dissolved lithium carbonate solution. The pressure was maintained at 0.05 atm and after 1 hour, the lithium hydroxide powder was recovered. The amount of the obtained lithium peroxide powder was 0.7 g. Lithium peroxide (Li ₂ O ₂ ) obtained in Example 1 was confirmed from the X-ray diffraction curve of FIG. 3. X-ray diffraction curve data for lithium peroxide (Li ₂ O ₂ ) are as follows.

Li ₂ O ₂ (ICDD: 09-0355): 23.328 ° (I _{rel .} 60), 32.902 ° (I _{rel .} 80), 35 ° (I _{rel .} 100), 40.605 ° (I _{rel .} 80), 58.681 ° (I _{rel .} 100)

3.5 g of water was added to the lithium peroxide powder. Evaporation pressure was maintained at 0.13 atm. The purity of the obtained lithium hydroxide monohydrate was analyzed using 35% HCl aqueous solution and phenolphthalein as an indicator, and the purity of 99%. In addition, XRD analysis was performed to confirm the structure of the recovered lithium hydroxide monohydrate. Figure 4 shows the XRD diffraction curve of the powder obtained in Example 1. X-ray diffraction curve data of lithium hydroxide monohydrate are as follows.

LiOHH ₂ O (ICDD: 09-0355): 30.063 ° (Irel. 66), 33.729 ° (Irel. 100), 36.962 ° (Irel. 45)

Example  2

In the same manner as in Example 1, about 1.2 g of lithium carbonate was dissolved in 100 g of distilled water in a reactor at a temperature of 10 ° C. 5 shows the XRD diffraction curves of the compound obtained in Example 2. FIG.

Example  3

In the same manner as in Example 1, about 2 g of lithium carbonate was dissolved in 100 g of distilled water in a reactor at a temperature of 110 ° C. 6 shows the XRD diffraction curves of the compound obtained in Example 3. FIG.

Example  4

In the same manner as in Example 1, 370 g of aqueous hydrogen peroxide solution was added. 7 shows the XRD diffraction curves of the compound obtained in Example 4. FIG. As can be seen from the results of Examples 1 to 4, as in Example 1, it was confirmed that pure lithium hydroxide monohydrate was not prepared unless the reaction temperature and the mass ratio of the reactants were precisely controlled.

Claims (7)

1 step of dissolving lithium carbonate in water to obtain an aqueous lithium carbonate solution;
Mixing the aqueous hydrogen peroxide solution with the aqueous lithium carbonate solution;
Evaporating the mixed solution to prepare lithium peroxide powder; And
4 steps of preparing lithium hydroxide monohydrate by adding water to the lithium peroxide powder and then evaporating
Method for producing lithium hydroxide monohydrate comprising a.
The method of claim 1, wherein the temperature in all the steps is carried out at 20 ~ 120 ℃.
The method for producing lithium hydroxide monohydrate according to claim 1, wherein the mass ratio of lithium carbonate to water in the first step is 0.5 to 1.5: 100.
The method for producing lithium hydroxide monohydrate according to claim 1, wherein the mass ratio of the aqueous hydrogen peroxide solution and the aqueous lithium carbonate solution in two steps is from 1: 1 to 150.
The method for producing lithium hydroxide monohydrate according to claim 1, wherein the pressure in the third step is 0.01 to 1 atm.
The method for producing lithium hydroxide monohydrate according to claim 1, wherein the mass ratio of the lithium peroxide powder and water in the four stages is 1: 5 to 50.
The method for producing lithium hydroxide monohydrate according to claim 1, wherein the pressure in the fourth step is 0.01 to 1 atm.

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