KR101472380B1 - FABRICATING METHOD OF Li2MnO3 BASE ADSORBENT AND ADSORBENT FABRICATED BY THE METHOD - Google Patents

Abstract

The present invention relates to a method for preparing an adsorbent based on Li ₂ MnO ₃ , comprising preparing and mixing a lithium compound and a manganese compound so that a molar ratio of lithium to manganese is 2: 1; Heat-treating the mixed material in air to form Li ₂ MnO ₃ ; And acid treating the Li ₂ MnO ₃ .
The present invention has an effect of providing a lithium adsorbent having a novel composition by producing an adsorbent based on Li ₂ MnO ₃ .
The present invention also provides heat treatment conditions and acid treatment conditions for preparing Li ₂ MnO ₃ -based adsorbents.
Further, the present invention provides a process for recovering lithium using an adsorbent based on Li ₂ MnO ₃ .

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method for producing an adsorbent based on Li2MnO3 and an adsorbent prepared thereby,

The present invention relates to a process for preparing a lithium adsorbent for recovering lithium, and more particularly to a process for preparing a new Li ₂ MnO ₃ -based adsorbent.

Recently, the development of electric cars and the rapid increase in the demand for portable electronic appliances such as smart phones and tablet PCs are rapidly expanding the lithium secondary battery market, and the demand for lithium used in lithium batteries is also rapidly increasing. However, the reserves of lithium resources are concentrated in some Central and South American countries. Bolivia, Chile and Argentina account for 80% of the world's reserves. Therefore, it is necessary to develop new technologies that can secure lithium resources to replace limited land resources in these limited areas. Recently, researches are being made on the development of an adsorbent having excellent adsorption performance capable of recovering lithium from seawater, wastewater, and lithium concentrated wastewater in addition to lithium resources mined from the land.

In the prior art, the most commonly studied and superior performance adsorbent precursor is the lithium-manganese oxide-based adsorbent. The lithium-manganese oxide-based adsorbent is generally based on LiMn ₂ O ₄ , and adsorbents of various compositions have been developed while varying the molar ratio of Li to Mn.

Typical compositions include LiMn ₂ O ₄ (Li / Mn = 0.50), Li 1 .5 Mn 2 O 4 (Li / Mn = 0.75), Li 1 .33 Mn 1 .67 O 4 (Li / Mn = 0.80) and Li ₁ Mn _{1 .6 .6} O ₄ (Li / Mn = 1.0). The theoretical performance of the lithium adsorbent can be considered to be related to the molar ratio of Li and Mn, and efforts to develop a new lithium adsorbent continue.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the prior art, and it is an object of the present invention to provide a method for producing a new adsorbent that selectively adsorbs lithium.

According to an aspect of the present invention, there is provided a method for preparing an adsorbent based on Li ₂ MnO ₃ , comprising: preparing and mixing a lithium compound and a manganese compound so that a molar ratio of lithium and manganese is 2: 1; Heat-treating the mixed material in air to form Li ₂ MnO ₃ ; And acid treating the Li ₂ MnO ₃ .

At this time, it is preferable that the lithium compound is Li ₂ CO ₃ and the manganese compound is MnCO ₃ .

Li ₂ MnO ₃ has been studied as a cathode material for a lithium battery, but it has not been developed as a lithium adsorbent. The inventors of the present invention have developed an optimal production method of Li ₂ MnO ₃ , which is considered to have a high theoretical adsorption performance, as an adsorbent because the molar ratio (Li / Mn) of Li and Mn is 2.0.

The heat treatment for forming Li ₂ MnO ₃ is preferably performed at 400 ° C. to 800 ° C. and is preferably performed at 450 ° C. to 550 ° C.

When the heat treatment is performed at a temperature lower than the above range, the reaction to form Li ₂ MnO ₃ does not progress. When the heat treatment is performed at a temperature higher than the range, the crystalline characteristic of Li ₂ MnO ₃ becomes too strong, The acid treatment is not smooth and the performance of the adsorbent deteriorates.

Further, the acid to be subjected to the acid treatment is preferably H ₂ SO ₄ or HNO ₃ .

In the case of HCl, it is preferable not to use HCl because the adsorbent performance deteriorates due to leaching of Mn together in the acid treatment.

And the concentration of the acid to be subjected to the acid treatment is preferably 2N to 6N. If the acid concentration is lower than this range, the acid treatment will not proceed, and if the acid concentration is too high, the performance of the adsorbent will deteriorate.

The temperature at which the acid treatment is performed is preferably 30 占 폚 or higher, and preferably 70 占 폚 or higher.

In carrying out the acid treatment, the ratio of Li ₂ MnO ₃ to the acid solution is preferably in the range of 3.0 g: 1.0 L to 10 g: 1.0 L.

The adsorbent based on Li ₂ MnO _{3 according} to another embodiment of the present invention is characterized in that it is produced by the above-mentioned method.

Also, the lithium recovery method according to the present invention is characterized in that lithium is recovered from a recovered solution using an adsorbent based on Li ₂ MnO ₃ produced by the above-described method.

At this time, the pH of the recovered solution is preferably 2.8 or more, and more preferably 5 or more. Li can not be recovered at pH below 2.8.

It is preferable that the time for recovering lithium from the recovered solution is 6 hours or more. When the recovery process is performed in less than 6 hours, the adsorption performance of the adsorbent can not be fully utilized.

The present invention constituted as described above has an effect of providing a lithium adsorbent of a new composition by producing an adsorbent based on Li ₂ MnO ₃ .

The present invention also provides heat treatment conditions and acid treatment conditions for preparing Li ₂ MnO ₃ -based adsorbents.

Further, the present invention provides a process for recovering lithium using an adsorbent based on Li ₂ MnO ₃ .

Figure 1 shows the result of thermogravimetric analysis of a mixture of Li ₂ CO ₃ and MnCO ₃ .
2 shows the results of XRD analysis according to the heat treatment temperature.
Fig. 3 is a field emission electron micrograph of the powder produced.
4 is a graph showing H ⁺ adsorption amount, Li ⁺ extraction amount and Mn ⁴⁺ extraction amount depending on the concentration of the acid solution and the acid treatment temperature.
5 is a graph showing Li ⁺ adsorption site formation according to the concentration of the acid solution and the acid treatment temperature.
FIG. 6 is a graph showing the amounts of H ⁺ adsorption, Li ⁺ extraction, and Mn ⁴⁺ depending on the ratio between the powder and the acid treatment solution and the acid treatment temperature.
7 is a graph showing Li ⁺ adsorption site formation according to the ratio between the powder and the acid treatment solution and the acid treatment temperature.
8 is a graph showing the amounts of H ⁺ adsorption, Li ⁺ extraction, and Li ⁺ adsorption site according to the heat treatment temperature in the process of manufacturing Li ₂ MnO ₃ .
FIG. 9 shows the results of XRD analysis of Li ₂ MnO ₃ -based adsorbent prepared according to this example.
10 is a field emission electron micrograph of a Li ₂ MnO ₃ -based adsorbent produced according to this example.
FIG. 11 shows the results of lithium recovery test according to the pH condition of the adsorbent prepared according to this embodiment.
12 shows the results of lithium recovery test according to the heat treatment temperature in the process of producing an adsorbent.
Fig. 13 shows the results of measurement according to the lithium recovery experiment time.

The present invention will be described in detail with reference to the accompanying drawings.

Li ₂ MnO ₃  Preparation of powder

In order to prepare a Li ₂ MnO ₃ powder, a lithium compound and a manganese compound are mixed and reacted by heating in an air atmosphere.

In this embodiment, Li ₂ CO ₃ and MnCO ₃ are mixed so that the molar ratio of Li and Mn is 2: 1, pulverized in an agate mortar, and then heated at a rate of 5 ° C / min to the heat treatment temperature in a heating furnace in an air atmosphere . The heat treatment temperature was classified into 500 ° C, 550 ° C, 600 ° C, 650 ° C and 700 ° C, and the heat treatment time was 40 hours.

In order to confirm the effectiveness of the preparation of Li ₂ MnO ₃ in the present embodiment, a mixture of Li ₂ CO ₃ and MnCO ₃ mixed at a molar ratio of Li and Mn of 2: 1 using a thermogravimetric analyzer (TGA, Seico Exstar 6000) Were subjected to thermogravimetric analysis. The analysis was carried out at a heating rate of 5 DEG C / min from 30 DEG C to 100 DEG C, and air was flown at a flow rate of 100 mL / min during the spraying.

Figure 1 shows the result of thermogravimetric analysis of a mixture of Li ₂ CO ₃ and MnCO ₃ .

A slight weight loss of less than 2% was observed around 200 ° C, but this is thought to result from the removal of moisture. In the range of 300 ° C to 900 ° C, the weight decreased by 40%, which is considered to be due to the formation of Li ₂ MnO ₃ and CO ₂ by a mixture of Li ₂ CO ₃ and MnCO _{3 according to} the following reaction formula.

Li ₂ CO ₃ (s) + MnCO ₃ (s) +? O ₂ (g)? Li ₂ MnO ₃ (s) + ₂ CO ₂ (g)

The start of the reaction at temperatures above 300 ° C is related to the temperature at which carbon dioxide is formed. From this, it can be seen that when the mixture of Li ₂ CO ₃ and MnCO ₃ is heated to 300 ° C. or higher in the state where oxygen exists, Li ₂ MnO ₃ can be formed.

Table 1 shows the chemical composition of the Li ₂ MnO ₃ powder prepared by the heat treatment at the above various heat treatment temperatures.

The table shows the heat treatment temperature of each powder, and the oxidation number of manganese is the result of assuming that the oxidation number of oxygen is -2.

As shown, the molar ratio of Li to Mn at all heat treatment temperatures ranged from 1.84: 1 to 1.93: 1, and the difference from the ideal stoichiometric ratio was determined by the moisture absorbed during the manufacturing process. However, since the difference from the ideal stoichiometric ratio is not large, it can be considered that Li ₂ MnO ₃ -based material for producing an adsorbent is produced.

2 shows the results of XRD analysis according to the heat treatment temperature.

When all the materials were annealed at 500 ℃ to 600 ℃, single phase monoclinic Li ₂ MnO ₃ belonging to C2 / m space group and having d ₀₀₁ value of 4.72 ~ 4.74 Å was obtained. Respectively. On the other hand, the d ₀₀₁ value of the powder heat treated at 700 ° C was 4.66 Å.

The diffraction peaks at around 20 ° to 25 ° correspond to superlattice peaks due to the stacking of lithium and manganese atoms located in the transition metal layer. This broad peak is due to the large number of defects present in the manufactured material.

The two-dimensional diffraction peaks observed at 64.7 ° and 65.7 ° are due to Li ₂ MnO _3. From this, it can be confirmed that the diffraction pattern according to the crystal structure is independent of the heat treatment temperature.

Fig. 3 is a field emission electron micrograph of the powder produced.

(a) to (e) are 50000 times magnified images of powders produced by heat treatment at 500 ° C, 550 ° C, 600 ° C, 650 ° C and 700 ° C, respectively.

In FIG. 3 (a), it is confirmed that spherical powders having various sizes of less than 3 μm are gathered in powders produced by heat treatment at 500 ° C. As the heat treatment temperature is higher, the surface of the powder is smoothed and the shape of the specific polyhedral crystal is exhibited. The polyhedral shape of FIG. 3 (e) produced at 700 ° C can be reliably confirmed.

The higher the annealing temperature, the larger the particle size is as observed in previous studies, and the results are consistent with the surface area results obtained by BET analysis.

The results of the BET analysis of the powder thus prepared are shown in Table 2.

As shown in FIG. 3, the surface area was reduced from 4.62 m ² / g to 1.49 m ² / g, and the pore size ranged from 8.4 nm to 14.2 nm Respectively.

Li ₂ MnO ₃ Acid treatment of

Next, in order to impart lithium adsorption property to Li ₂ MnO ₃ , the produced powder is subjected to an acid treatment.

In this embodiment, acid treatment was performed using HCl, HNO _3, and H ₂ SO ₄ , respectively. The adsorbent prepared by performing the acid treatment was washed with distilled water and centrifuged at 4 ° C. at 12,000 rpm for 20 minutes Restored. The adsorbent which had been rinsed and recovered until the pH of the solution was nearly equal to the distillation was dried in an oven at 60 ° C.

In order to confirm the influence of the kind of acid used in the acid treatment, acid treatment was performed on the powders prepared at the temperatures of 500 ° C. and 700 ° C. with the above three kinds of acids under the same conditions.

HCl, HNO _3, and H ₂ SO ₄ were prepared at a concentration of 2.5 N, respectively, and mixed with 1.0 g of Li ₂ MnO ₃ powder in an acid solution ratio of 25 mL, stirred at 750 rpm at room temperature for 24 hours, Respectively.

Table 3 shows the results of performing the acid treatment on the powders prepared at the heat treatment temperature of 500 ° C, and Table 4 shows the acid treatment results of the powders prepared at the heat treatment temperature of 700 ° C.

According to the Table 3 and Table 4, it can be seen in the Li ₂ MnO ₃ powder produced a flow in the case of acid treatment in the Li ₂ MnO ₃ powder prepared in 500 ℃ at 700 ℃ much more when treated with acid. This result is because Li ₂ MnO ₃ powder prepared at 700 ° C has a relatively excellent crystallographic structure, as confirmed in the field emission electron micrograph and the XRD analysis.

Of the acid solutions, the HCl solution showed the highest utilization of H ⁺ in solution and extraction ability of Li ⁺ and Mn ⁴⁺ for both powders. However, the HCl solution is not suitable for the acid treatment of Li ₂ MnO ₃ powder for producing lithium adsorbents, since it causes excessive leaching of Mn ⁴⁺ .

H ₂ SO ₄ solution and HNO ₃ solution had less leaching amount of Li ⁺ than HCl solution, but leaching amount of Mn was also very small, less than 1%. According to the acid-treated H ₂ SO ₄ solution and HNO ₃ solution the Li ₂ MnO are suitable for the acid treatment of the _three powders, H ₂ SO ₄ takes a small amount of the preparation of an acid solution of the required normal concentration compared to the HCl solution Which is more suitable.

In order to confirm the effects of the acid treatment conditions, acid treatment was carried out by varying the concentration of the acid solution and the acid treatment temperature. Li ₂ MnO ₃ powder prepared at 700 ° C. was used as powder for acid treatment because of low amount of Li ⁺ leaching at the beginning of the acid treatment. The powder was mixed with 1.0 g of Li ₂ MnO ₃ powder in an amount of 25 mL of acid solution, The acid treatment was carried out with stirring for a period of time.

4 is a graph showing H ⁺ adsorption amount, Li ⁺ extraction amount and Mn ⁴⁺ extraction amount depending on the concentration of the acid solution and the acid treatment temperature.

5 is a graph showing Li ⁺ adsorption site formation according to the concentration of the acid solution and the acid treatment temperature.

In all the concentration ranges, as the acid treatment temperature rises from 30 ° C to 75 ° C, the extraction amount of Li ⁺ increases as shown in Figs. 4 (c) and 4 (d) As a result, it is possible to confirm that the adsorption site of Li ⁺ is elongated, and it is also expected that the Li ₂ MnO ₃ produced at different temperatures should be treated with an acid at 75 ° C.

It is because Fig. 4 (a) and Figure 4 (b) is a Li ⁺ H ⁺ compared to utilization increasing phenomenon H ⁺ is adsorbed into the surface material extraction, as indicated.

The higher the concentration of the acid solution from 2.5N to 7.5N, 4 (c) and Figure 4 as shown in (d), reducing the extractable content of Li ^+, and the Li ⁺ as thus illustrated in Figure 5 thereof Adsorption sites also decrease. And, at all concentrations and temperature ranges, the extraction amount of Mn ⁴⁺ is less than 2% of the total Mn content.

From the above results, in a case where with respect to a Li ₂ MnO ₃ heat-treated at 700 ℃ heat-treated at a temperature of 75 ℃ with H ₂ SO ₄ solution of 2.5N was to determine the highest lithium extractable content of 64.4%, which is Li ⁺ / H ⁺ 85% of total Li ⁺ extraction based on ion exchange mechanism.

In order to investigate the effects of the mass of Li ₂ MnO ₃ powder and the volume ratio of the acid treatment solution, the Li ₂ MnO ₃ powder prepared at 700 ° C was mixed with 2.5N H ₂ SO ₄ solution at a rate of 750 rpm The acid treatment was carried out with stirring for a period of time.

FIG. 6 is a graph showing the amounts of H ⁺ adsorption, Li ⁺ extraction, and Mn ⁴⁺ depending on the ratio between the powder and the acid treatment solution and the acid treatment temperature.

7 is a graph showing Li ⁺ adsorption site formation according to the ratio between the powder and the acid treatment solution and the acid treatment temperature.

As shown in FIG. 7, Li ⁺ adsorption site production decreases as the volume ratio of the acid treatment solution increases and the mass ratio of Li ₂ MnO ₃ powder decreases. This seems to be due to the decrease in the extraction amount of Li ⁺ as the total amount of H ⁺ increases, which is consistent with the case where the concentration of the acid solution is high.

When the best Li extraction ratio is 64.4%, the mass of the Li ₂ MnO ₃ powder heat-treated at 700 ° C and the volume of the 2.5N H ₂ SO ₄ solution are 4.0g: 1.0L.

As described above, the optimal acid treatment conditions for the Li ₂ MnO ₃ powder prepared by heat treatment at 700 ° C., in which the leaching performance of Li ⁺ was not high, were confirmed and summarized as follows.

The most suitable acid for the acid treatment is H ₂ SO ₄ and the concentration of the acid solution is 2.5N. It is also preferable that the suitable acid treatment temperature is 75 캜, the mass ratio of Li ₂ MnO ₃ powder to the volume ratio of the acid solution is 40 g: 1.0 L, and the acid treatment time is 24 hours.

Hereinafter, the Li ₂ MnO ₃ powder produced at various heat treatment temperatures is subjected to an acid treatment under the optimum acid treatment conditions to prepare a lithium adsorbent and compare the properties thereof. In order to distinguish the adsorbent produced by performing the acid treatment, it is indicated by attaching H after the heat treatment temperature.

8 is a graph showing the amounts of H ⁺ adsorption, Li ⁺ extraction, and Li ⁺ adsorption site according to the heat treatment temperature in the process of manufacturing Li ₂ MnO ₃ .

As shown, exhibited the best Li ⁺ adsorption site generation of the prepared heat-treated in 500 ℃ Li ₂ MnO ₃ powder and a Li ₂ MnO ₃ prepared by heat treatment at 650 ℃ powder.

It is manufactured by the heat treatment in 500 ℃ Li ₂ MnO ₃ powder and is manufactured by heat-treating at 650 ℃ Li ₂ MnO ₃ powder exhibited a Li + extractable content of 85.23% and respectively 90.9%, and this value theoretically according to the ion exchange with H ⁺ 21.2% and 13.6% higher than the Li ⁺ extractable amount. This indicates that Li ⁺ is extracted from the slab octahedral site where Mn and Li are located in the crystallographic structure of Li ₂ MnO ₃ .

On the other hand, Li ₂ MnO ₃ powder prepared by heat treatment at 550 ° C and 650 ° C and 700 ° C showed lower value than Li ⁺ extractable amount of 75% according to ion exchange mechanism.

The utility of H ⁺ shown in Figs. 8 (a) and 8 (b) is similar to Li ⁺ extracted from each Li ₂ MnO ₃ . It was confirmed again that Mn was stable in the H ₂ SO ₄ solution because no Mn was detected in the solution even when the acid treatment was carried out for 24 hours. The resulting Li ⁺ adsorption sites showed 65 ~ 89% based on the actual Li ⁺ content of Li ₂ MnO ₃ .

Table 5 shows the contents of H, Li, and Mn by acid-based titration for each adsorbent prepared by acid treatment and the elemental analysis results by ICP-MS.

As a result of the elemental analysis and the comparison of Li and Mn contents calculated based on the extracted data, the tendency of the content of Li contained in the produced Li ₂ MnO ₃ was slightly smaller than that of elemental analysis, All of the methods were consistent. According to the extracted data, Li ⁺ content of Li ₂ MnO ₃ decreased to 72.5 ~ 90.2% after acid treatment.

The content of Mn in Li ₂ MnO ₃ identified on the basis of the extracted data increased to 6.0 ~ 8.16% after acid treatment, and this value was higher in elemental analysis. This is due to the fact that the formula of the adsorbent is predicted once the actual oxidation number of Mn is determined.

FIG. 9 shows the results of XRD analysis of Li ₂ MnO ₃ -based adsorbent prepared according to this example.

As shown, even after the acid treatment, the diffraction peaks slightly shifted laterally and the peak located at 45 ° collapsed. The weak but broad peak in the 21 ° to 23 ° range is due to the maintenance of the Li-Mn arrangement in the shear and Mn-rich layers of the stacked oxygen plane from O 3 to P ₂ , which maintains the structure of Li ₂ MnO ₃ .

10 is a field emission electron micrograph of a Li ₂ MnO ₃ -based adsorbent produced according to this example.

(a) to (e) are 50000 times magnified images of the adsorbent prepared on the basis of Li ₂ MnO ₃ powder prepared by heat-treating at 500 ° C, 550 ° C, 600 ° C, 650 ° C and 700 ° C, respectively.

As a result of the acid treatment, the overall shape of the rod was crystalline and some spherical particles were clustered.

The process of forming such a bar shape is as follows. First, cleavage occurs due to ion exchange with H ⁺ in the Li layer, and lattice shrinkage is accompanied. This shrinkage generates strong stress and shape distortion on the contact surface of unreacted Li ₂ MnO ₃ to form cracks, and cracks promote the extraction of Li ⁺ and produce plate-like particles. It is believed that rod-shaped particles are formed by dissolving Li in the LiMn ₂ plate and breaking into a bar shape after forming the tunnel structure.

The results of the BET analysis of the Li ₂ MnO ₃ -based adsorbent prepared according to this example are shown in Table 6.

Compared with before the acid treatment, the surface area increased greatly by 17 ~ 56 times after the acid treatment, and the greatest increase was observed in the adsorbent based on Li ₂ MnO ₃ prepared by heat treatment at 650 ° C.

This change in surface area is a result of the change of the microsized spherical and polyhedral microspheres before the acid treatment to the nano-sized microspheres after the acid treatment, as confirmed by the above-mentioned field emission electron microscope photograph.

Except for Li ₂ MnO ₃ prepared by heat treatment at 650 ℃, the surface area after acid treatment decreased with increasing heat treatment temperature. Li ₂ MnO ₃ prepared at 650 ° C showed similar results as the adsorbent prepared at 6500 ° C.

The pore size calculated by BET analysis ranged from 8.5 nm to 12.1 nm. The pore size of the adsorbent prepared by acid treatment of Li ₂ MnO ₃ heat-treated at 700 ° C was about 14% The pore size was similar to that before the acid treatment, except for a significant decrease.

Li ₂ MnO ₃ Determination of the effect of lithium-based adsorbent on lithium recovery

Hereinafter, the Li ₂ MnO ₃ -based adsorbent produced according to the present embodiment is subjected to a lithium recovery experiment to confirm the effect and optimum recovery conditions.

First, in order to confirm the effect of recovering lithium according to the pH condition, lithium recovery experiment was performed using Li ₂ MnO ₃ -based adsorbent prepared by heat treatment at 500 ° C. to LiOH solution adjusted to pH 2, 7 and 11.

The pH was adjusted by using 5.0N HCl solution and the concentration of the solution was adjusted to 7.0 ppm by using a 1000 ppm LiCl solution. 50 mg of the adsorbent was added to 50 ml of the LiOH solution, and a lithium recovery test was conducted at a temperature of 25 캜 for 5.5 days.

FIG. 11 shows the results of lithium recovery test according to the pH condition of the adsorbent prepared according to this embodiment.

Fig. 11 (a) shows the pH change of the solution before and after the lithium recovery experiment, and Fig. 11 (b) shows the lithium adsorption ability according to the pH.

As shown in FIG. 11 (a), the pH of the solution having pH 2 slightly increased without any change in pH even after the lithium recovery experiment. However, the pH and the solution having pH 7 and 11 decreased greatly after the experiment. This change in pH indicates that the Li ⁺ ion in the solution has been exchanged with the H ⁺ ion, and it can be considered that the recovery of lithium has progressed greatly.

As shown in FIG. 11 (b), the higher the initial pH of the recovered solution, the better the lithium adsorption performance of the adsorbent prepared according to this example. On the other hand, the leaching of Li occurred in the solution with the initial pH of 2, and it was confirmed that the leaching of Li occurred when the initial pH of the solution was 2.8 or less.

In the solution with pH 7, the adsorbent lithium recovery capacity was 0.96 ± 0.17 (mg Li ⁺ / g adsorbent). However, in the solution with pH 11, the lithium recovery capacity of the adsorbent was improved to 5.12 ± 0.03 (mg Li ⁺ / g adsorbent).

In order to investigate the effect of heat treatment temperature on the adsorbent production process, lithium recovery experiment was conducted using Li ₂ MnO _{3 -} based adsorbent prepared by heat treatment at various temperatures.

1 g of the adsorbent was added to 50 ml of the recovered solution having a pH of 13 and a Li concentration of 825 ppm, and a lithium recovery test was conducted at a temperature of 25 캜 for 5.5 days.

12 shows the results of lithium recovery test according to the heat treatment temperature in the process of producing an adsorbent.

FIG. 12 (a) shows the pH change of the solution before and after the lithium recovery experiment, and FIG. 12 (b) shows the lithium adsorption ability according to the heat treatment temperature.

In Fig. 12 (a), the pH after the recovery experiment was slightly decreased because the initial pH of the recovered solution was high.

As shown in FIG. 12 (b), the adsorbent recovery capacity was in the range of 13.1 to 23.5 mg Li ⁺ / g adsorbent, and the Li ₂ MnO ₃ -based adsorbent prepared by heat treatment at 500 ° C was the highest, The adsorbent based on Li ₂ MnO ₃ prepared by heat treatment was the next highest.

The maximum amount of lithium adsorption performance that can be achieved when all the Li + ions in the solution are adsorbed is 31.7 to 57.0%, but the theoretical lithium adsorption performance calculated from the Li extraction experiment in the acid treatment is 17.3 to 23.5%. Further, in the recovery experiment for the solution of pH 13, leaching of Mn was observed, but leaching was less than 1% of the total Mn of the adsorbent.

In order to confirm the equilibrium time of the lithium adsorption reaction, the lithium recovery experiment using Li ₂ MnO _{3 -} based adsorbent prepared by heat treatment at 500 ° C. was performed and the change with time was observed.

1 g of the adsorbent was added to 1.0 L of the recovered solution having a pH of about 11 and a Li concentration of 7 ppm, and a lithium recovery experiment was conducted at a temperature of 25 캜 for 6 days.

Fig. 13 shows the results of measurement according to the lithium recovery experiment time.

13 (b) is a graph showing the change in Li ⁺ concentration of the recovered solution and the lithium adsorption performance of the adsorbent according to the time period of the lithium recovery experiment. FIG. 13 (a) is a graph showing the pH change of the recovered solution according to the lithium recovery test time, to be.

As shown in Fig. 13 (a), the pH of the recovered solution was lowered from 11.2 to 6.5 in the initial 6 hours. The pH of the recovered solution is a good parameter indicating that the equilibrium state has been reached by the progress of the ion exchange, and it can be considered that the lithium adsorption reaction equilibrated in about the initial 6 hours.

As shown in FIG. 13 (b), the Li concentration contained in the recovered solution was lowered from 7.39 ± 0.09 ppm to 0.59 ± 0.12 ppm within 6 hours. The equilibrium concentration slightly increased after 96 hours at equilibrium. The adsorption performance of the adsorbent was confirmed to be 6.80 ± 0.12 (mg Li ⁺ / g adsorbents).

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Those skilled in the art will understand. Therefore, the scope of protection of the present invention should be construed not only in the specific embodiments but also in the scope of claims, and all technical ideas within the scope of the same shall be construed as being included in the scope of the present invention.

Claims (15)

Preparing and mixing a lithium compound and a manganese compound so that a molar ratio of lithium to manganese becomes 2: 1;
Heat-treating the mixed material in air to form Li ₂ MnO ₃ ; And
Treating the Li ₂ MnO ₃ with an acid,
The temperature for performing the heat treatment is 400 ° C. to 800 ° C.,
Wherein the acid which performs the acid treatment is H ₂ SO ₄ or HNO ₃ ,
The method of Li ₂ MnO _3-based adsorbent, characterized in that the temperature for performing the acid treatment not less than 30 ℃. The method according to claim 1,
The lithium compound is Li ₂ CO ₃ in the method of manufacturing the adsorbent based on Li ₂ MnO _3, characterized. The method according to claim 1,
The manganese compound is MnCO ₃ The method of producing a Li ₂ MnO _3, characterized in that based adsorbent. delete The method according to claim 1,
Method of producing a Li ₂ MnO ₃ based adsorbent, characterized in that the temperature for performing the heat treatment of 450 ℃ ~ 550 ℃. delete The method according to claim 1,
The method of Li ₂ MnO _3-based adsorbent, characterized in that the concentration of the acid to perform the acid treatment of 2N ~ 6N range. delete The method according to claim 1,
The method of Li ₂ MnO _3-based adsorbent, characterized in that the temperature for performing the acid treatment not less than 70 ℃. The method according to claim 1,
The ratio of Li ₂ MnO ₃ and acid solution performing the acid treatment is in the range of 3.0 g: 1.0 L to 10 g: 1.0 L,
The concentration of the acid solution is a 2N ~ 6N range of the adsorbent production method of Li ₂ MnO _3, characterized in based. An adsorbent based on Li ₂ MnO ₃ , which is produced by one of claims 1 to 3, 5, 7, 9 and 10. A lithium recovery method, comprising recovering lithium from a recovered solution using the adsorbent of claim 11. The method of claim 12,
Wherein the pH of the recovered solution is at least 2.8. The method of claim 12,
Wherein the pH of the recovered solution is 5 or more. The method of claim 12,
Wherein the time for recovering lithium from the recovered solution is 6 hours or more.

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