KR102033607B1 - Method for concentrating of lithium by addition of aluminum compound and sulfation reaction from lithium solution and recycling method of by-product made thereby - Google Patents

Abstract

An aspect of the present invention provides a method for concentrating lithium by addition of an aluminum compound and sulfation reaction from a lithium solution and a recycling method of a by-product during concentration, wherein the method comprises following steps of: (a) adding the aluminum compound to the lithium solution to form a lithium-aluminum layered double hydroxide and separating an unreacted aluminum-containing liquid; (b) sulfating the lithium-aluminum layered double hydroxide to produce lithium sulfate, and separating an aluminum compound residue; and (c) reusing the unreacted aluminum-containing liquid of the step (a) and the aluminum compound residue of the step (b) with the aluminum compound of the step (a).

Description

METHOD FOR CONCENTRATING OF LITHIUM BY ADDITION OF ALUMINUM COMPOUND AND SULFATION REACTION FROM LITHIUM SOLUTION AND RECYCLING METHOD OF BY-PRODUCT MADE THEREBY}

The present invention relates to a method of concentrating lithium by adding a specific aluminum compound from a lithium solution to form a lithium-aluminum compound, and sulfate-reacting it, and a method of recycling process water and waste solids generated during concentration.

The process for producing a lithium compound (lithium carbonate, lithium hydroxide, etc.) from a lithium-containing solution is generally made by reacting a carbonate or hydroxide with a lithium solution having a concentration of lithium ions of 30,000 ppm or more. For example, in the process of preparing a lithium compound from lithium of brine, an alkali solvent is added to a lithium solution in which lithium ions are concentrated by 6% or more through natural evaporation to remove impurities, and then to the lithium solution from which impurities are removed. There is a method of producing lithium carbonate or lithium hydroxide by reacting carbonate (sodium carbonate) or hydroxide (calcium hydroxide).

However, the lithium extraction process with natural evaporation is limited regionally, such as South America (Chile, Argentina, etc.), the concentration method through heating or decompression is required in the lithium concentration process required for the lithium compound manufacturing process, such The energy-concentrating process acts as a major factor in raising the manufacturing cost of lithium compounds. Therefore, various concentration methods have been proposed to overcome this problem.

There is a lithium adsorption method for recovering lithium ions by adsorbing lithium ions using an adsorption material having a selectivity to lithium ions and then reacting a desorbent such as an acid solution. As a method of preparing the concentrated lithium solution through the adsorption method, there is a method of increasing the lithium concentration of the acid desorption solution by repeatedly applying the acid desorption solution used in the process of desorbing the adsorbed lithium ions to the desorption process.

However, in order to increase the concentration of lithium ions, the molar ratio of H / Li contained in the desorption liquid must be maintained above a certain value, and the adsorption material component (Mn ion in the case of Li-Mn-O) may be Incorporation into the concentrated lithium solution requires additional purification, and the number of repeated use of the adsorbent due to the loss of Mn components is limited.

In the case of the solvent extraction method, the concentrated lithium solution can be prepared by using a repeated desorption solution (acid solution) similarly to the above adsorption method, but unlike the adsorption method, since the selectivity is low, impurity components are mixed during the concentration process before the extraction / Further purification is required later.

In the precipitation method, a method of separating and recovering a lithium solution and an insoluble lithium compound by reacting a precipitant capable of forming an insoluble compound after reaction with lithium ions is common. However, in the case of the precipitant used, since the selectivity to lithium ions is low, impurities other than lithium may be co-precipitated with an insoluble compound when impurity ions are present.

Phosphoric acid (phosphate, sodium phosphate, etc.) or an aluminum compound is known as a precipitant for separating lithium ions, and lithium phosphate (Li ₃ PO ₄ ) or lithium-aluminum layered double hydroxide (Li-Al layered double hydroxide) is used. In general, a method of converting an insoluble compound in the form of LiAl ₂ (OH) ₇ 2H ₂ O) to separate the lithium solution from the lithium solution is common.

In the case of lithium phosphate, the solubility in water is 0.034 g / 100 mL, which limits the lithium recovery rate when the lithium solution reacts with the phosphate precipitant, thereby limiting the recovery of lithium ions below a certain concentration. Lithium-aluminum compounds have lower solubility characteristics than lithium phosphate, and thus lithium recovery has higher advantages than precipitation using phosphoric acid. However, when aluminum is recovered through precipitation through aluminum, an excessive amount of aluminum (Li / Al molar ratio of 0.5 or less) is required. As a result, a solution separated from an insoluble lithium compound contains an excessive amount of aluminum ions. Aluminum ions are contaminants that must be removed during the water treatment process, and are accompanied by high costs for removing aluminum ions during the water treatment process.

As a related prior document, there is a "high efficiency lithium recovery method from a lithium solution" disclosed in Korean Patent Publication No. 10-1944519.

Korean Registered Patent Publication 10-1944519

The present invention is to solve the above-mentioned problems of the prior art, an object of the present invention is to provide a method for concentrating lithium from a low concentration lithium solution through the aluminum compound and sulfate reaction, and recycling the aluminum by-products generated at this time have.

In order to achieve the above object, an aspect of the present invention comprises the steps of (a) adding an aluminum compound to the lithium solution to form a lithium-aluminum layered double hydroxide, and separating the unreacted aluminum-containing liquid; (b) sulfating the lithium-aluminum layered double hydroxide to produce lithium sulfate, and separating the aluminum compound residue; And (c) reusing the unreacted aluminum-containing liquid of step (a) and the aluminum compound residue of step (b) with the aluminum compound of step (a). It provides a lithium concentration method through the reaction and a by-product recycling method when concentrated.

According to an aspect of the present invention, an environmentally friendly process may be realized by reusing an aluminum ion-containing solution generated when the low concentration lithium solution is concentrated through an aluminum compound addition and sulfation process as a reaction raw material. In addition, there is an advantage that can be reused as a reaction raw material by reprocessing the insoluble aluminum compound that is separated during the sulfation process.

The effects of the present invention are not limited to the above-described effects, but should be understood to include all the effects deduced from the configuration of the invention described in the detailed description or claims of the present invention.

1 and 2 are schematic diagrams illustrating a lithium concentration method and a by-product recycling method when concentrated by adding an aluminum compound and a sulfation reaction from a lithium solution according to an embodiment of the present invention.
3 is a graph showing the results of XRD analysis of the lithium-aluminum compound formed in Example 1 of the present invention.
4 is a graph showing the results of XRD analysis of the lithium-aluminum compound formed in Examples 3 and 4 of the present invention.
FIG. 5 is a graph showing XRD analysis results of sodium aluminate (NaAlO ₂ ) produced through the reaction of aluminum residue (Al ₂ O ₃ ) and caustic soda formed in Examples 5 and 6 of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Advantages and features of the present invention, and methods for achieving the same will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings.

However, the present invention is not limited by the aspects disclosed below, but can be embodied in various different forms, only the present aspects make the disclosure of the present invention complete, and those skilled in the art to which the present invention pertains. It is provided to fully inform the person of the scope of the invention.

In addition, in the following description of the present invention, if it is determined that related related technologies and the like may obscure the gist of the present invention, detailed description thereof will be omitted.

One aspect of the present invention,

(A) adding an aluminum compound to the lithium solution to form a lithium-aluminum layered double hydroxide, and separating the unreacted aluminum-containing liquid (S10);

(b) sulphating the lithium-aluminum layered double hydroxide to produce lithium sulfate, and separating the aluminum compound residue (S20); And

(c) adding the unreacted aluminum-containing liquid of step (a) and the aluminum compound residue of step (b) to the aluminum compound of step (a) (S30), adding an aluminum compound from a lithium solution, and It provides a method for concentrating lithium through a sulfation reaction and a method for recycling by-products when concentrated.

In the method of concentrating a lithium by adding an aluminum compound and a sulfation reaction from a lithium solution according to an aspect of the present invention and recycling a by-product during concentration, the step (a) is performed by adding a specific aluminum compound to a lithium solution to form a lithium-aluminum layer. The double hydroxide is formed and the unreacted aluminum ion containing liquid is separated for reuse in subsequent steps.

The lithium concentration of the lithium solution of step (a) may be 5 ppm to 10000 ppm.

The aluminum compound of step (a) may be one selected from the group consisting of sodium aluminate, aluminum sulfate, aluminum hydroxide, alumina and combinations thereof. Wherein the aluminum compound is added, and the layered double hydroxide containing lithium and aluminum (layered double hydroxide) may be formed, which is _{LiAl 2 (OH) 6 A ·} xH 2 O (A = Cl -, OH -, NO 3 ^- , CO ₃ ^- and the like, x may be represented by an integer of 1 to 10) form.

The step (a) may be performed so that the molar ratio of Al / Li [lithium of aluminum / lithium solution of aluminum compound] is 1 to 2.5. When the aluminum compound is added less than the molar ratio, lithium recovery and concentration efficiency may be lowered. When the aluminum compound is excessively added compared with the molar ratio, a large amount of aluminum by-products may be generated to increase the treatment cost. have. In the above molar ratio range, aluminum by-products can be easily processed in a subsequent step, and the concentration of the low concentration lithium solution can be performed with high recovery rate.

After the addition of the aluminum compound of step (a), the reaction may be sufficiently performed by standing or stirring for 0.1 to 24 hours.

The layered double hydroxide produced through the addition of the aluminum compound of step (a) may be insoluble and precipitated in solution to be solid-liquid separated. When the solid-liquid separation is a filtrate is a solution containing aluminum ions, it can be reusable by treating in a step to be described later.

In the lithium concentration method through the addition of aluminum compounds and sulfation reaction from the lithium solution according to an aspect of the present invention, and the by-product recycling method when concentrated, step (b) (S20) is the sulfation of the lithium-aluminum layered double hydroxide The reaction was carried out to produce lithium sulfate, and the resulting aluminum compound residue was separated.

The sulfation reaction of step (b) may be performed by roasting and adding sulfuric acid or aluminum sulfate to the lithium-aluminum layered double hydroxide. At this time, the roasting temperature may be 200 ℃ to 800 ℃. If roasting is carried out below the temperature range, there is a risk that the sulfidation reaction may not be sufficiently carried out to reduce the lithium recovery and concentration efficiency, if roasting is carried out above the temperature range, there is a fear of melting during the reaction, excessive Energy waste may occur.

The sulfation reaction of step (b) is the lithium-aluminum layered double hydroxide is LiAl ₂ (OH) ₇ · xH ₂ O, when the reaction is made through sulfuric acid or aluminum sulfate, it can be made as in Scheme 1 or 2. have.

Scheme 1

_{2LiAl 2 (OH) 7 · xH} 2 O + H 2 SO 4 → Li 2 SO 4 + 2Al 2 O 3 + (2x + 8) H 2 O

Scheme 2

_{6LiAl 2 (OH) 7 · xH} 2 O + Al 2 (SO 4) 3 → 3Li 2 SO 4 + 7Al 2 O 3 + (6x + 21) H 2 O

(In the above Reaction Scheme 1 or 2, x is an integer of 1 to 10.)

In step (b), the sulfated reaction may add 1 to 2 equivalents of sulfuric acid-containing material relative to lithium of a lithium-aluminum compound in consideration of the above reaction schemes.

Through the step (b), aluminum oxide may be formed of lithium sulfate and by-products, and the aluminum oxide may be treated and reused in a subsequent step.

The lithium sulfate formed through the step (b) may be dissolved in water to prepare a high concentration lithium sulfate aqueous solution, and lithium carbonate may be added to the lithium aqueous solution to form lithium carbonate, or the lithium hydroxide solution may be converted into a lithium hydroxide solution. It can be used as a lithium raw material of various forms.

In the lithium concentration method through the addition of aluminum compounds and sulfuric acid reaction from the lithium solution according to an aspect of the present invention and the by-product recycling method when concentrated, step (c) (S30) is containing the unreacted aluminum of step (a) The liquid and the aluminum compound residue of step (b) are reprocessed to be reused as the aluminum compound of step (a).

The unreacted aluminum-containing liquid of step (c) is a solution in which aluminum ions that have not reacted when the lithium-aluminum compound is formed through the addition of aluminum in step (a) remain and are evaporated to concentrate the aluminum in step (a). It can be used as a compound. At this time, the evaporation concentration may be performed to evaporate 3/4 to 4/5 of the aluminum ion solution. The evaporation concentration can be carried out through Mechanical Vapor Recompression (MVR).

In step (c), sodium hydroxide solution or sodium hydroxide powder is added to the aluminum compound (alumina) residue as a by-product of step (b), and sodium aluminate hydrate (NaAl (OH) ₄ ) or sodium aluminate (NaAlO ₂ ). It may include the step of switching to. The converted sodium aluminate hydrate is suitable for reuse because it has a higher reaction efficiency with lithium than the aluminum compound before conversion, and thus lithium concentration can be easily performed.

As described above, the lithium concentration method through the addition of aluminum compounds and the sulfation reaction from the lithium solution according to an aspect of the present invention and the recycling method of by-products when concentrated to treat the aluminum by-products generated in each reaction process for easy reuse, There is the effect of realizing the process and reducing additional costs.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. However, the following Examples and Experimental Examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

<Example 1>

(a) After preparing a lithium solution (Li concentration of 1000 mg / L), sodium aluminate (NaAlO ₂ ) powder was added and reacted for 24 hours under an Al / Li molar ratio of 2.5. The lithium-aluminum compound formed after the reaction was precipitated and filtered, which was washed with cold water and dried at 60 ° C.

(b) 1 g of the lithium-aluminum layered double hydroxide prepared in the above step and 10 mL of 10% sulfuric acid solution (H ₂ SO ₄ ) are physically mixed, followed by a temperature of 290 ° C. and an air atmosphere in a box-type kiln. Heat treatment for 2 hours to form a lithium sulfate and aluminum compound.

(c) after separating the precipitated material of step (a), the filtrate was concentrated through a reduced pressure concentration process, the material produced in step (b) was washed with water to separate the aluminum compound and added to the aqueous solution of sodium hydroxide The clav reactor was used to convert sodium aluminate hydrate via reaction at 170 ° C. In addition, the aluminum compound separated in step (b) was mixed with sodium hydroxide powder was converted to sodium aluminate through the reaction at 1100 ℃.

<Example 2>

In Example 1, the lithium solution was changed to 5000 mg / L, and the Al / Li molar ratio was changed to 0.2, except that the same procedure as in Example 1 was performed.

<Example 3>

In Example 1, the lithium solution was changed to 1500 mg / L, and the Al / Li molar ratio was changed to 2, except that the same procedure as in Example 1 was performed.

<Example 4>

(a) the aluminum by-products generated in steps (a) and (b) of Example 1 were added to a lithium solution (Li concentration of 1500 mg / L) under an Al / Li molar ratio of 2 and reacted for 24 hours. After the same as in Example 1.

Experimental Example 1 XRD and ICP Analysis of Lithium and Aluminum Reactants

XRD analysis of the lithium-aluminum compound formed after the step (a) of Example 1 was performed, and the results are shown in FIG. 3. Referring to FIG. 3, it can be seen that a lithium-aluminum compound in the form of a layered double hydroxide is formed.

In addition, as a result of ICP analysis of the lithium-aluminum compound of Example 1, the ratio of lithium and aluminum of the formed lithium-aluminum compound was found to be 0.48 (theoretical value 0.5).

Experimental Example 2 Concentration Analysis of the Filtrate During Lithium-Aluminum Reaction

After performing steps (a) of Examples 1 and 2, the aluminum ion concentration and the lithium ion concentration of the separated filtrate were measured, and the results are shown in Table 1.

Referring to Table 1, in Example 1 having an aluminum / lithium molar ratio of 2.5, it can be seen that the aluminum ion concentration remaining in the filtrate reaches approximately 3105 ppm, and the lithium ion concentration is below the detection limit, indicating that lithium in the initial lithium solution It was confirmed that all the ions were converted. On the other hand, in Example 2 having an aluminum / lithium molar ratio of 0.2, the residual lithium ion concentration reached 3709 ppm, and the aluminum ion concentration was found to be 393 ppm.

Experimental Example 3 XRD Analysis of a Lithium-Aluminum Compound Generated by Recycling Aluminum By-Products

The XRD analysis of the lithium-aluminum compound produced in step (a) of Example 4 and Example 3 utilizing reprocessing of the aluminum by-product generated in Example 1 was performed, and the results are shown in FIG. 4. Referring to FIG. 4, even though the reaction was performed using recycled aluminum by-products, the composition of the product was almost similar to that of Example 3, and it was found that the concentration of the lithium solution was easily achieved by utilizing the reused aluminum by-products.

Experimental Example 4 of sodium aluminate hydrate (NaAl (OH) ₄ ) and sodium aluminate (NaAlO ₂ ) prepared by adding sodium hydroxide solution and sodium hydroxide powder to the aluminum compound (alumina) residue as a by-product of step (b). XRD Analysis

After mixing the aluminum by-product (alumina) and caustic soda solution generated in Example 1, it was observed that the amorphous sodium aluminate hydrate was formed from the XRD analysis of the product prepared at 170 ℃ using an autoclave reactor. It can be seen that the raw material grade sodium aluminate was formed from the XRD result of the product recovered through the heat treatment at 200 ℃. In addition, it was found that sodium aluminate could be prepared by heat treatment of the aluminum byproduct (alumina) and the caustic soda powder mixture at 1100 ° C.

So far, the lithium concentration method and the by-product recycling method when concentrated by adding an aluminum compound and a sulfation reaction from a lithium solution according to an aspect of the present invention, but various embodiments are modified within the scope of the present invention. Possibility is obvious.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

That is, the above-described aspects are to be understood in all respects as illustrative and not restrictive, the scope of the invention being indicated by the claims that follow, rather than the detailed description. All changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention.

Claims (8)

(a) adding an aluminum compound to the lithium solution to form a lithium-aluminum layered double hydroxide and separating the unreacted aluminum containing liquid;
(b) sulfating the lithium-aluminum layered double hydroxide to produce lithium sulfate, and separating the aluminum compound residue; And
(c) reusing the unreacted aluminum-containing liquid of step (a) and the aluminum compound residue of step (b) with the aluminum compound of step (a), wherein the aluminum compound is added and sulfated As a lithium concentration method through
In step (a), an aluminum compound is used such that the Al / Li molar ratio (the lithium molar ratio of the aluminum / lithium solution of the aluminum compound) is 2 to 2.5. Method for concentrating lithium through compound addition and sulfation reaction.
The method according to claim 1,
Lithium concentration of the lithium solution of the step (a) is characterized in that 5 ppm to 10000 ppm, lithium by-product recycling including aluminum by-product recycling and lithium concentration method through the sulfation reaction.
The method according to claim 1,
The aluminum compound of step (a) is one selected from the group consisting of sodium aluminate, aluminum sulfate, aluminum hydroxide, alumina and combinations thereof. Method of Concentrating Lithium Through the Chemical Reaction.
The method according to claim 1,
Step (a) is carried out so that the Al / Li molar ratio (lithium molar ratio of the aluminum / lithium solution of the aluminum compound) is 2.5, aluminum compound addition and sulfated from the lithium solution, including aluminum by-product recycling Lithium concentration method through the reaction.
The method according to claim 1,
The sulfation reaction of step (b) is performed by adding sulfuric acid or aluminum sulfate to the lithium-aluminum layered double hydroxide, and roasting the same. Lithium concentration method.
The method according to claim 5,
The roasting temperature of the step (b) is characterized in that 200 ℃ to 800 ℃, lithium by-product recycling, including the aluminum by-product recycling and lithium concentration method through the sulfidation reaction.
The method according to claim 1,
Wherein (c) is characterized in that it comprises the step of evaporating and condensing the unreacted aluminum-containing liquid, aluminum by-product recycling including lithium by-product recycling and lithium concentration method through the sulfated reaction.
The method according to claim 1,
Step (c) is the addition of the aluminum compound from the lithium solution, including the aluminum by-product recycling, comprising the step of adding sodium hydroxide solution or powder to the aluminum compound residue to convert to sodium aluminate hydrate or sodium aluminate and Method for concentrating lithium through sulfate reaction.

Images