Resource recovery methods

Abstract

To provide a method for recovering resources, capable of recovering a Li element contained in a waste liquid as a resource.SOLUTION: A method for recovering a resource, according to the present disclosure, is provided which recovers a resource from a waste liquid containing a hydrophobic compound, an alcohol compound, and a lithium alkoxide, the method including: a first step of adding a basic solution to the waste liquid to obtain a lithium hydroxide-containing phase; and a second step of drying the lithium hydroxide-containing phase to obtain a solid component containing lithium hydroxide.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This disclosure relates to a method for resource recovery.

Background Art

[0002] Information-related devices and communication devices such as personal computers, video cameras, and mobile phones are becoming widespread. Also, from the perspective of reducing the environmental load, automobiles using motors such as electric vehicles are becoming widespread. Along with this, various studies are being conducted on the batteries used as their power sources.

[0003] For example, Patent Document 1 discloses Si particles having a class rate structure used as an active material and a method for producing the Si particles.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When producing materials used in batteries, it is assumed that waste liquid will be generated. Also, such waste liquid may contain metal elements such as Li element. From the perspective of building a recycling-based society, it is desired to recover the Li element contained in such waste liquid as a resource.

[0006] This disclosure has been made in view of the above circumstances, and the main object thereof is to provide a resource recovery method capable of recovering the Li element contained in waste liquid as a resource.

Means for Solving the Problems

[0007] [1] A method for recovering resources from waste liquid containing hydrophobic compounds, alcohol compounds, and lithium alkoxides, The first step involves adding a basic solution to the above waste liquid to obtain a lithium hydroxide-containing phase. A method for recovering resources, comprising: a second step of drying the lithium hydroxide-containing phase to obtain a solid component containing lithium hydroxide.

[0008] [2] The method for recovering resources according to [1], wherein the concentration of the above basic solution is 10% by weight or more and 30% by weight or less.

[0009] [3] The method for recovering resources according to [1] or [2], wherein the basic solution is an aqueous ammonia solution.

[0010] [4] A method for recovering resources according to any one of [1] to [3] above, wherein the waste liquid contains the element Si. [Effects of the Invention]

[0011] This disclosure offers the advantage of recovering the Li element contained in the waste liquid as a resource. [Brief explanation of the drawing]

[0012] [Figure 1] This is a flowchart illustrating the resource recovery method described in this disclosure. [Figure 2] These are the results of the XRD measurements in the example. [Modes for carrying out the invention]

[0013] The resource recovery methods described in this disclosure are explained in detail below.

[0014] Figure 1 is a flowchart illustrating the resource recovery method in this disclosure. As shown in Figure 1, in the resource recovery method in this disclosure, first, a basic solution is added to a waste liquid containing a hydrophobic compound, an alcohol compound, and lithium alkoxide to obtain a lithium hydroxide-containing phase (first step). Then, the lithium hydroxide-containing phase is dried to obtain a solid component containing lithium hydroxide (second step).

[0015] According to this disclosure, lithium in lithium alkoxide can be recovered as lithium hydroxide by adding a basic solution to waste liquid containing hydrophobic compounds, alcohol compounds, and lithium alkoxide.

[0016] Lithium hydroxide is a useful material in battery manufacturing. For example, lithium hydroxide is used as a main raw material for positive electrode materials.

[0017] 1. Waste liquid The waste liquid in this disclosure contains hydrophobic compounds, alcohol compounds, and lithium alkoxides.

[0018] Examples of hydrophobic compounds include compounds having a benzene ring and compounds not having a benzene ring. Examples of compounds having a benzene ring include aromatic hydrocarbons such as 1,3,5-trimethylbenzene (mesitylene), toluene, xylene, ethylbenzene, propylbenzene, cumene, 1,2,4-trimethylbenzene, and 1,2,3-trimethylbenzene, as well as ethers (ethers having a benzene ring) such as diphenyl ether and methylphenyl ether. Examples of compounds not having a benzene ring include saturated hydrocarbons such as n-heptane, n-octane, n-decane, 2-ethylhexane, and cyclohexane; unsaturated hydrocarbons such as hexene and heptene; and ethers (ethers not having a benzene ring) such as n-butyl ether, n-hexyl ether, isoamyl ether, diphenyl ether, methylphenyl ether, and cyclopentyl methyl ether.

[0019] Examples of the alcohol compound include primary alcohols such as methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, and 1-hexanol; secondary alcohols such as 2-propanol, 2-butanol, 2-pentanol, and 2-hexanol; and tertiary alcohols such as tert-butyl alcohol.

[0020] Examples of the lithium alkoxide include compounds composed of an anion of the above-described alcohol compound and a lithium ion. For example, lithium methoxide, lithium ethoxide, lithium iso-propoxide, lithium tert-butoxide, and lithium tert-pentoxide can be mentioned.

[0021] Further, the waste liquid may contain Si element. The Si element may be contained in the waste liquid in the state of, for example, Si metal and Si compound. Examples of the Si metal include simple substances of Si metal and Si alloys such as Li-Si alloy. Examples of the Si compound include tetraethoxysilane.

[0022] Further, the waste liquid may contain an acid. Examples of the acid include carboxylic acids such as acetic acid, formic acid, and propionic acid, and dicarboxylic acids such as oxalic acid.

[0023] The source of the waste liquid in the present disclosure is not particularly limited. For example, the waste liquid in the present disclosure may be a waste liquid generated when manufacturing an active material of a battery. In particular, when containing Si element, the waste liquid may be a waste liquid generated when manufacturing a Si-based active material.

[0024] 2. First Step The first step in the present disclosure is a step of adding a basic solution to the above waste liquid to obtain a lithium hydroxide-containing phase. By reacting the above lithium alkoxide with the basic solution, lithium in the lithium alkoxide can be recovered as lithium hydroxide.

[0025] The concentration of the basic solution is not particularly limited, as long as it is an amount sufficient for the lithium alkoxide in the waste liquid to react sufficiently. The concentration may be, for example, 10.0% by weight or more, 12.5% ​​by weight or more, or 15.0% by weight or more. On the other hand, the concentration may be, for example, 30.0% by weight or less, 25.0% by weight or less, or 20.0% by weight or less. Considering the reaction equilibrium, a higher concentration is more preferable.

[0026] The amount of basic solution added can be adjusted as appropriate depending on the amount of waste liquid and the above concentration, but for example, it is 1.0 to 10.0 by volume relative to the waste liquid.

[0027] Examples of basic solutions include aqueous solutions of metal hydroxides such as sodium hydroxide aqueous solution, calcium hydroxide aqueous solution, and potassium hydroxide aqueous solution, as well as nonmetallic aqueous solutions such as ammonia aqueous solution.

[0028] The lithium hydroxide-containing phase typically contains at least the above-mentioned alcohol compound in addition to lithium hydroxide. Furthermore, the lithium hydroxide-containing phase may also contain the above-mentioned hydrophobic compound and the above-mentioned acid.

[0029] 3.Second process The second step in this disclosure is to dry the lithium hydroxide-containing phase to obtain a solid component containing lithium hydroxide.

[0030] The drying conditions are not particularly limited as long as a solid component can be obtained from the lithium hydroxide-containing phase. In other words, the drying conditions are not particularly limited as long as the liquid can be removed from the lithium hydroxide-containing phase. The drying temperature is, for example, 100°C or higher, may be 120°C or higher, or 150°C or higher. On the other hand, the drying temperature is, for example, 200°C or lower. The drying time is, for example, 5 minutes or more, may be 10 minutes or more, or 30 minutes or more, on the other hand, the drying time is, for example, 1 hour or less.

[0031] Furthermore, as shown in Figure 1, in the second step, the liquid components contained in the lithium hydroxide-containing phase may be recovered by the drying process. In other words, the drying process may be performed by distillation. The liquid components are at least one of the alcohol compound, the hydrophobic compound, and the acid. Thus, in the resource recovery method described herein, liquid components such as hydrophobic compounds contained in the wastewater can also be recovered as resources.

[0032] The proportion of lithium hydroxide in the solid component is not particularly limited, but a high proportion is preferable. For example, the proportion of lithium hydroxide in the solid component may be 50% by weight or more, 70% by weight or more, or 90% by weight or more. On the other hand, the proportion of lithium hydroxide in the solid component may be 100% by weight or less, 99% by weight or less, or 95% by weight or less.

[0033] 4. Other processes In the resource recovery method described herein, the first step is a step of separating the wastewater into an aqueous layer and an oil layer by adding the basic solution, and if the aqueous layer is the lithium-containing phase, the method may also include a third step of distilling the oil layer to recover at least one of the hydrophobic compound and the alcohol compound. The distillation conditions in the third step, such as the heating temperature, can be appropriately adjusted depending on the types of hydrophobic compounds and alcohol compounds contained in the wastewater.

[0034] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and achieves similar effects is included within the technical scope of this disclosure. [Examples]

[0035] [Example 1] Lithium hydroxide was recovered from the waste liquid based on the flow shown in Figure 1. Specifically, 5 ml of a solution (waste liquid) containing mesitylene, ethanol, and lithium ethoxide was first prepared. A 20% by weight aqueous ammonia solution was added to this solution in a 1:1 volume ratio, and the mixture was shaken and allowed to stand. This separated the waste liquid into an oil layer and an aqueous layer (lithium hydroxide-containing phase). The aqueous layer was recovered and heated at 120°C for 20 minutes to precipitate a solid component (white powder).

[0036] [evaluation] X-ray diffraction (XRD) measurements were performed on the obtained white powder. The results are shown in Figure 2. Figure 2 also includes the XRD measurement results of the waste liquid used as reference data.

[0037] As shown in Figure 2, the lithium hydroxide peak was observed as the main peak in the example, confirming that high-purity lithium hydroxide can be recovered by the method disclosed herein. In the example, a 20% by weight aqueous ammonia solution was used, but considering the reaction equilibrium, it is presumed that even higher-purity lithium hydroxide can be recovered by using a more concentrated basic solution.

Claims

1. A method for recovering resources from waste liquid containing hydrophobic compounds, alcohol compounds, and lithium alkoxides, The first step involves adding a basic solution to the waste liquid to obtain a lithium hydroxide-containing phase. A method for recovering resources, comprising a second step of drying the lithium hydroxide-containing phase to obtain a solid component containing lithium hydroxide.

2. The method for recovering resources according to claim 1, wherein the concentration of the basic solution is 10% by weight or more and 30% by weight or less.

3. The method for recovering resources according to claim 1, wherein the basic solution is an aqueous ammonia solution.

4. The method for recovering resources according to any one of claims 1 to 3, wherein the waste liquid contains the element Si.

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