WO2016032138A1 - Method and apparatus for extracting lithium from coal ash - Google Patents

Abstract

The present invention relates to a method and an apparatus for extracting lithium from coal ash and, more specifically, to a method and an apparatus for extracting lithium, wherein the lithium is extracted from coal ash using an extraction solvent and microwaves, and thus the coal ash can be reutilized through a simplified process, and the extraction rate of lithium can be improved.

Description

Method and apparatus for extracting lithium from coal ash

The present invention relates to a method and apparatus for extracting lithium from coal ash, and more particularly, to a method and apparatus for extracting lithium contained in coal ash using an extraction solvent and microwave.

Lithium is a raw material for heat-resistant magnetic, heat-resistant glass, raw materials for pharmaceutical salts, headache drugs, anticancer drugs, heart drugs, and nausea treatment drugs, raw materials for molten salt, electrolytic additives for TV, tube additives for tube, electric welding rod, bleach sterilization, lithium ion battery, nuclear fusion Applications such as blankets for furnaces and rechargeable secondary batteries continue to increase.

Lithium extraction and recovery technology, which is increasing in usage for this purpose, is mostly achieved through quarrying operations in lithium-containing ore gangs. Lithium ore is a pegmatite deposit, and the main components of the pegmatite deposit are Amblygonite [(Li, Na) Al (PO ₄ ) (F, OH)], Eucryptite [LiAlSiO ₄ ] , Lepidolite [K (Li, Al) ₃ (Si, Al) ₄ O ₁₀ (F, OH) ₂ , Petalite [Li ₂ O · Al ₂ O ₃ · 8SiO ₂ , LiAlSi ₄ O _10], sports dyumin _{(Spodumene) [Li 2 O ·} Al 2 O 3 · 4SiO 2, LiAlSi 2 O 6] consists of minerals, the recovery of lithium from pegmatite deposits is accompanied by a quarried in advance, transportation and storage operations In addition, processing techniques such as crushing, heavy liquids, screening, crushing, classification, flotation, etc. are applied to further enhance the quality of lithium minerals. In particular, the mined deposit is made of ore, and then subjected to a pulverization process and a fine grinding process to purify various impurities and to increase the concentration of lithium, that is, floating screening process. Therefore, a large amount of lithium is disposed in the middle, so the lithium extraction rate is as low as 25%.

Also, in quarrying, most of the lithium is obtained from the pegmatite deposits in which minerals such as Amblygonite, Lepidolite, Eucryptite, Petalite and Spodumene are obtained. It is accompanied by transportation and storage process. In addition to the chemicals added prior to the lithium extraction process, crushing, pulverization, and calcite removal processes to increase the reaction surface area are incurred a lot of costs, and is separately studying the recycling of gangue and calcite such as waste generated after lithium recovery. .

Pre-processed Spodumene ore fine powder exists in nature as α-Spodumene (Li ₂ O · Al ₂ O ₃ · 8SiO ₂ ), so β-Spodumene (Li ₂ O · Al ₂₎ is highly soluble in sulfuric acid. O ₃ · ₄ SiO ₂ ) to be converted to β-spodumene and silica (Free Silica, SiO ₂ ) when calcined at 1,100 ℃.

_{Li 2 O · Al 2 O 3} · 8SiO 2 → Li 2 O · Al 2 O 3 · 4SiO 2 + 4SiO 2

When sulfuric acid is mixed slightly with the theoretical amount of β-spodumene and heated to about 250 ° C. in a sulfuric acid roasting furnace, only Li ₂ O in β-spodumene crystallizes into lithium sulfate (Li ₂ SO ₄ ).

Li ₂ OAl ₂ O ₃ 4SiO ₂ + H ₂ SO ₄ → Li ₂ SO ₄ + Al ₂ O ₃ 4SiO ₂ + H ₂ O ↑

After mixing with water to make lithium sulfate solution, the excess sulfuric acid is neutralized with lime and the gypsum formed is filtered off like alumina and silica. After the semen is reacted with a saturated solution of soda ash, lithium carbonate precipitates.

Li ₂ SO ₄ + Na ₂ CO ₃ → Li ₂ CO ₃ ↓ + Na ₂ SO ₄

As such, lithium recovery and extraction from ore is a technique for recovering lithium from spodumene, which is most abundant in reserves. First, the spodumene is converted from α-spodumene to β-spodumene by heating to 1,050-1,150 ° C. α-spodumene is not readily soluble in acids, but β-spodumene is readily soluble in acids. After cooling the concentrated concentrate, it is pulverized, sulfuric acid is added to form a slurry, and then heated to about 200 to 250 ° C. Water is added to this slurry to form a Li ₂ SO ₄ solution, and then limestone is added to remove iron and aluminum, followed by filtration to remove calcium and magnesium by adding lime and soda ash. Thereafter, neutralized with sulfuric acid and evaporated to concentrate Li ₂ SO ₄ to 200-250 g / L. Soda ash is added again and heated to 90 ~ 100 ℃ to precipitate lithium carbonate (Li ₂ CO ₃ ). Na ₂ SO ₄ remaining in the recovered Li ₂ CO ₃ is washed and then evaporated to generate by-products. In commercial processes, the extraction rate is around 20-25%.

On the other hand, as a lithium extraction source worldwide, seawater is used next to lithium ore, and lithium is present in the seawater at a concentration of about 170 to 200 ppb. Coal ash, on the other hand, is concentrated at around 200-300 ppm, 1,000 times higher than seawater. However, although 870 million tons of coal ash is generated annually and 60 million tons of landfill ash is generated in Korea, its use is insufficient.

An object of the present invention is to provide a method and apparatus for extracting lithium by using coal ash, which is a waste generated in a thermal power plant, as a raw material.

In addition, the present invention skips the mining, grinding, fine powder, sorting, firing and roasting process to obtain a conventional lithium, and a method and apparatus for extracting lithium present in the coal ash in the form of margarite crystals of fine powder The purpose is to provide.

In addition, an object of the present invention is to provide a method and apparatus for extracting lithium from coal ash having improved lithium extraction rate compared to the conventional lithium extraction method.

The present invention comprises the steps of reacting the coal ash and the extraction solvent; And irradiating the microwaves to obtain a solution containing lithium.

The fly ash is preferably that contains margarite _{(margarite) [Ca 0 .922 Li} 0 .452 Al 2 Si 2 O 10 .02] crystal.

The extraction solvent preferably contains 0.1 to 2.0N sulfuric acid.

The extraction solvent preferably further comprises nitric acid or hydrochloric acid.

The reaction of the coal ash and the extraction solvent is preferably carried out at room temperature shaking conditions.

Irradiating the microwaves is preferably carried out at 60 to 90 ℃ hot water conditions.

The coal ash and the extraction solvent is preferably reacted at a high liquid ratio of 0.05 to 0.50 g / mL.

It is preferable to further include the step of generating a lithium salt by performing a salt formation reaction to the solution containing lithium.

The present invention is a coal ash feed device (4); Extraction solvent supply device (1); And a microwave extraction device for reacting the coal ash and the extraction solvent supplied from the coal ash supply device 4 and the extraction solvent supply device 1, and irradiating microwaves to the reacted coal ash and extraction solvent to form a solution containing lithium. Provided is an apparatus for extracting lithium from coal ash, comprising (5).

It is preferable to further include an extraction solvent mixing device (3) for diluting the extraction solvent supplied from the extraction solvent supply device (1), and to supply the diluted extraction solvent to the microwave extraction device (5).

It is preferable to further include a circulation pipe 12 for circulating the solution containing lithium to the extraction solvent mixing device (3).

It is preferable to further include a crystallization reaction apparatus 8 for generating a lithium salt by performing a salt formation reaction to the solution containing lithium.

According to the present invention, instead of the pegmatite deposit used to extract conventional lithium, by using coal ash discarded in a thermal power plant or the like as a lithium extraction source, the lithium extraction process can be simplified and the lithium extraction rate can be significantly improved. .

In addition, by recycling a large amount of coal ash generated and discarded, it is possible to use environmentally friendly resources, and can economically reduce costs.

In addition, by improving the extraction rate of the extracted lithium, more efficient resourceization is possible.

In addition, a concentration process for increasing the content of lithium through recycling of the solution containing lithium is possible.

1 is a schematic view showing one embodiment of an apparatus for extracting lithium from coal ash of the present invention.

Fig. 2 is a schematic diagram showing one embodiment of the microwave extraction apparatus 5 used in the apparatus for extracting lithium from the coal ash of the present invention.

Fig. 3 is a schematic diagram showing one embodiment of a system for operating the microwave extraction apparatus 5 used in the apparatus for extracting lithium from the coal ash of the present invention.

4 is a crystal structure analysis result of the analysis of coal ash obtained from domestic thermal power plants by X-ray diffractometer (XRD: X-ray diffractometer).

Figure 5 is a photograph of the analysis of the components of coal ash obtained from domestic thermal power plants by scanning electron microscopy (SEM, scanning electron microscopy).

6 is a glassy and crystalline structure diagram of coal ash.

7 is a graph showing a change in concentration of lithium according to the number of cycles of the present invention.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

The present invention comprises the steps of reacting the coal ash and the extraction solvent; And irradiating microwaves to obtain a solution containing lithium, and a method for extracting lithium from coal ash and an apparatus using the same. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

To time (re), the fly ash is generated after combustion, etc. coal-fired power plant, is not particularly limited, and the coal ash is margarite _{(margarite) [Ca 0 .922 Li} 0 .452 Al 2 Si 2 O 10 .02] determined It is preferable to include. May include specifically coal-fired at a high temperature of 1200 ~ 1400 ℃ etc. Mark plant of the coal ash after melt crystallization light _{[Ca 0 .922 Li 0 .452 Al} 2 Si 2 O 10 .02] determined, the average of the fly ash The particle size may be a spherical body of 15-25 μm.

The coal ash particles may include a core representing a crystalline phase, a layer representing a glassy phase, and a surface layer, each of which may include lithium. For example, as shown in FIG. 6, the core of the particle is a particle in which lithium is bonded to the margarite crystal, lithium is contained in the glassy material positioned between the core and the surface, and lithium is adsorbed on the surface. Can be.

The extraction solvent which is primarily reacted with the coal ash may use an acid. In this case, sulfuric acid, hydrochloric acid, nitric acid and the like may be used, but it is more preferable to use sulfuric acid in that the lithium component can be easily converted to water-soluble lithium sulfide (Li ₂ SO ₄ ) than other components. At this time, sulfuric acid is preferably used as the extraction solvent 0.1 to 2.0N sulfuric acid. When the concentration of sulfuric acid is less than 0.1N as the extraction solvent, the content of lithium extracted from the primary reaction with coal ash may be low, and when the concentration exceeds 2.0N, impurities such as silica, alumina, calcium and magnesium as well as lithium may be There may be problems with extraction at the same time.

In extracting lithium from the coal ash, it is connected to a water supply device 14, a secondary solid-liquid separator 15, a dehydration device (10, 16), a lithium carbonate solid separator (9), and the like to mix the extraction solvent The device 3 may additionally be provided. That is, the extraction solvent supplied from the extraction solvent supply device 1 is transferred to the extraction solvent mixing device 3 which may be further provided before the extraction solvent supplied to the microwave extraction device 5, and the extraction solvent mixing device ( By reacting the water and the extraction solvent supplied from the water supply device 14 which may be further provided in 3), the concentration of the extraction solvent can be adjusted to a desired range. In addition, it is possible to reuse the water used in the process, and to recover the lithium remaining in the water, it is possible to minimize the amount of lithium discarded.

In addition, the extraction solvent mixing apparatus 3 may be supplied with nitric acid or hydrochloric acid as an additional extraction solvent to assist sulfuric acid from the extraction solvent auxiliary supply device 2, the kind of the additional extraction solvent is limited It is not.

The coal ash and the extraction solvent respectively supplied from the coal ash supply apparatus 4 and the extraction solvent supply apparatus 1 are conveyed to the microwave extraction apparatus 5, and react primarily, It is preferable to make it react on room temperature shaking conditions. In this case, the room temperature conditions may be, for example, a temperature condition of 20 to 30 ℃, even if heated outside the temperature range to 30 ℃ or more does not increase the extraction rate of lithium that is surface-adsorbed or bonded to the glassy coal ash There is a problem. Therefore, surface adsorption and most of the glassy bound lithium can be extracted at the room temperature.

In addition to the dilution of the extraction solvent, the water supply device 14 for supplying water to adjust the concentration of the extraction solvent may supply water to the water washing device 13 which has undergone solid-liquid separation.

In the first reaction at room temperature in the microwave extraction apparatus 5, the solid-liquid ratio of the coal ash and the extraction solvent is preferably reacted at 0.05 to 0.50 g / mL. That is, the extraction ratio of lithium may be influenced by the ratio of the mass of coal ash and the volume of the extraction solvent, and when the solid-liquid ratio exceeds 0.50 g / mL, the contact surface area of the extraction solvent and the coal ash may be reduced. When the lithium extraction rate cannot be secured and the solid solution ratio is less than 0.05 g / mL, the economic efficiency may be reduced due to excessive use of the extraction solvent.

In the microwave extraction device 5, the coal ash and the extraction solvent are first reacted with each other, and then irradiated with microwaves to cause a secondary reaction. That is, it is preferable to use the microwave to extract lithium present in the surface layer and the glassy layer of the coal ash particles from the extracting solvent and to extract lithium present in the core of the particle.

The microwave is a kind of electromagnetic wave (300MHz ~ 300GHz) located between the far infrared and radio waves (high frequency) in the spectrum, because the heating method uses the friction force by the molecular rotation or rearrangement by the speed corresponding to the frequency of the electromagnetic wave. It is possible to increase the temperature faster than the thermal conductivity heating. In addition, the energy of microwaves has a low energy that does not damage chemical bonds and therefore does not alter or destroy the molecular structure.

The step of irradiating the microwave is preferably carried out in a 60 to 90 ℃ hot water bath conditions, when the temperature range is less than 60 ℃, the secondary lithium extraction efficiency by the microwave is difficult to improve the lithium extraction rate, the temperature range If the temperature exceeds 90 ℃, the amount and extraction rate of the extract due to the evaporation of water can be reduced, the temperature is increased above the boiling point, the pressure is applied to the extraction reactor, and the compression reactor must be configured additionally, the equipment is complicated Can be done.

In addition, by irradiating with the microwave, to obtain a solution containing lithium, it may be further provided with a circulating pipe 12 that can be circulated back to the extraction solvent mixing device (3), containing the circulated lithium The solution is to increase the concentration of lithium contained in the solution while going through the step of extracting the lithium of the present invention, it is possible to concentrate the lithium. For example, by circulating the solution containing lithium nine or more times through the circulation pipe 12, as shown in FIG. 7, it is possible to obtain lithium concentrated at 200 ppm or more, and by controlling the number of cycles, The target lithium concentration can be determined.

The lithium-containing solution, which is generated after irradiating microwaves in a secondary reaction, may be transferred to a crystallization reactor 8 capable of conducting a salt formation reaction, and may be transferred to the crystallization reactor 8. The solution containing lithium may generate a lithium salt such as lithium carbonate (Li ₂ CO ₃ ) through a salt formation reaction with sodium carbonate (Na ₂ CO ₃ ) or the like.

At this time, the method of supplying the sodium carbonate or the like to the crystallization reaction device 8 for the salt formation reaction is not particularly limited, for example, sodium carbonate supply device (8-1) and the like connected to the crystallization reaction device (8) It may be further provided.

Further, the lithium carbonate produced through the salt formation reaction can be selectively transferred to the extraction solvent mixing apparatus 3 or the dehydration / drying apparatus 10 and 11 after undergoing a high temperature separation process, and the extraction solvent mixing apparatus 3 When circulated to), it is possible to obtain an effect that can further concentrate the content of lithium.

On the other hand, after passing through the primary solid-liquid separator (6) in the microwave extraction device (5), and separating residues other than the solution containing lithium, the residue is subjected to the second liquid through the washing device (13) Separation 15 may then be optionally transferred to extraction solvent mixing apparatus 3 or dehydration / drying apparatus 16, 17. In this case, when the extraction solvent is transferred to the mixing device (3), it is subjected to the lithium extraction process of the present invention again to be recycled, and when transported to the dehydration / drying device (16.17), the by-products to coal admixture for concrete admixtures, etc. Recyclable.

Hereinafter, the present invention will be described in more detail with reference to examples, but the embodiments according to the present invention can be modified in various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. do.

< Example  1 to 12>

Coal ash supply apparatus 4 as shown in the schematic diagram shown in FIG. 1; Extraction solvent supply device (1); And a microwave extraction device for reacting the coal ash and the extraction solvent supplied from the coal ash supply device 4 and the extraction solvent supply device 1, and irradiating microwaves to the reacted coal ash and extraction solvent to form a solution containing lithium. The apparatus which extracts lithium from the coal ash containing (5) was produced.

2 is a view showing an example of the microwave extraction apparatus 5 in more detail. The microwave extraction apparatus 5 includes a microwave irradiation supply unit 5-3 for supplying microwaves into the microwave extraction apparatus 5. ; A reactor (5-5) made of Teflon, a material having a low permittivity, for the purpose of permeation of supplied microwaves; A microwave reflection stirrer (5-4) for reflecting some microwaves reflected from the upper and lower plates and transmitted through the reactor (5-5) of the microwave extraction device (5) back to the reactor (5-5); A reactor top plate (5-6) made of Teflon material having a low dielectric constant and excellent chemical resistance to prevent erosion from the extraction solvent reacting inside the reactor (5-5); Stainless steel stirring device (5-2) coated with Teflon on the outside for even mixing of the coal ash and extraction solvent and microwave reflection; A temperature sensor 5-10 shielding by coating Teflon on the outside of stainless steel for measuring microwave temperature to control microwave output; A vapor condenser 5-11 for preventing a change in moisture composition inside the reactor 5-5; An extraction solvent supply part 5-9 connected to the extraction solvent supply device 1 and supplying the extraction solvent to the microwave extraction device 5; A coal ash supply unit 5-8 connected to the coal ash supply device 4 and supplying coal ash to the microwave extraction device 5; And a leakage choke (5-14) for preventing the leakage of microwaves.

Furthermore, the outer plates (5-13, 5-18) are made of aluminum oxide material with high microwave transmission resistance to block external leakage of microwaves, and the reactor (5-5) is made of Teflon material with high microwave transmittance and The supports 5-7 transmit microwaves, and ceramic bricks were used to increase the bearing capacity. In addition, the part in contact with the extraction solvent was configured to use the Teflon having excellent chemical resistance and heat resistance and low dielectric constant to smoothly penetrate the microwave into the reactor 5-5 and prevent erosion of the reactor.

3 is a diagram specifically showing an example of a system for extracting microwaves 5 including a microwave extracting apparatus 5. A system for smoothly irradiating microwaves in the microwave extracting apparatus 5, the magnetron 5-3-6 serving as an output supply apparatus for irradiating microwaves supplied to the microwave extracting apparatus 5; A tuner 5-3-2 for minimizing a very small amount of microwaves reflected from the microwave extraction device 5 and matching microwaves and loads; A coupler 5-3-3 which transmits a signal to the magnetron 5-3-6 and an output control device by measuring the intensity of the microwaves reflected and incident on the microwave extraction device 5; A dummy load 5-3-8 which serves to absorb and remove the microwaves reflected from the microwave extraction device 5 to protect the magnetron 5-3-6; A circulator 5-3-4, which serves to protect the magnetron 5-3-6 by directing the microwaves reflected from the microwave extraction device 5 back to the dummy rod so as not to return; A temperature sensor 5-3-12 for measuring an increase in temperature through microwave irradiation inside the reactor 5-5; A temperature control device 5-3-10 connected to the temperature detection device 5-3-12 and used to adjust an output; Output control device that serves to maintain a constant temperature by stopping or reducing the output when the temperature in the reactor (5-5) reaches a predetermined temperature or more according to the signal transmitted from the temperature control device (5-3-10) ( 5-3-9); And a microwave detector (5-3-11) for detecting microwave leakage around the microwave extraction device (5) which may affect the environment of the operator. In this case, the microwave output is designed to be variable up to 180W, 360W, 900W, 1260W, 1800W, 2000W.

In the embodiment, the microwave extraction device 5 is 2.45GHz, 2kW, 220V, single phase, the volume of the reaction device is 2L, the diameter is 20cm, the stirring speed for the bath condition is adjusted to 100 ~ 500rpm The thermometer used a thermocouple shielded by coating Teflon on the outside of stainless steel.

1. Analysis result of coal ash obtained from domestic thermal power plant

As a result of analyzing the components of coal ash obtained from domestic Dangjin thermal power plant, silica (SiO ₂ ) and alumina (Al ₂ O ₃ ) are the main components, and zirconium (Zr) and lithium (Li) are high among rare metals as shown in Table 1 below. appear. As shown in FIGS. 4 and 5, the analysis of the lithium crystal structure included in the coal ash includes _margarite [Ca _0.922 Li _0.452 Al ₂ Si ₂ O _10.02 ] crystals.

TABLE 1

2. Preparation of Extraction Solvent

97% industrial sulfuric acid (specific gravity 1.84 kg / L, molecular weight 98.08 g / mole) was used to prepare an extraction solvent that reacts primarily with coal ash. The normal concentration of the industrial sulfuric acid is 36.34N, from which 0.1N (diluted with 1.75 mL sulfuric acid in 1L of water), 0.5N (diluted with 13.74mL sulfuric acid in 1L of water), 1N (diluted with 27.48mL sulfuric acid in 1L of water) , 2N (diluted with 54.96 mL sulfuric acid in 1L of water) was controlled to be prepared in the extraction solvent mixer (3), respectively.

3. Coal ash  And microwave irradiation after extraction solvent reaction

The coal ash was reacted by transferring the prepared sulfuric acid with an extraction solvent to a microwave extraction device (5). At this time, as shown in Table 2, the coal ash was mixed and reacted with 0.05 to 0.50 g / mL of solid-liquid ratio (coal ash g / sulfuric acid extraction solvent mL) to 0.1-2.0N sulfuric acid. At this time, the reaction conditions were reacted for 3 hours at a stirring speed of 150rpm at 25 ℃ conditions as shown in Table 2.

Thereafter, the reaction product was microwaved in the microwave extraction device 5 to raise the temperature to 90 ° C. At this time, when the temperature exceeds 90 ° C, the power was cut off, and when the temperature was lowered below 90 ° C, the power was turned on. Was adjusted. The reaction was carried out for 30 minutes at a stirring speed of 100 rpm under the same temperature conditions.

The concentration of lithium extracted from the coal ash in the solution thus obtained was measured, and the extraction rate was calculated through a ratio with the concentration of the initial lithium of the coal ash and is shown in Table 3.

< Comparative example  1 to 12>

In a high temperature roasting method for extracting lithium from the coal ash, sulfuric acid was used as the extraction solvent and heated to 200 ° C. for 3 hours in a commercial BTC Mason 800 roaster (MASON-800, BTC).

Thereafter, the roasted coal ash, which has been roasted, was diluted with water, and lithium ions were dissolved from the diluted coal ash.

< Comparative example  13 to 24>

In Examples 1 to 12, except that irradiated with microwaves, the same was carried out, lithium was extracted through Comparative Examples 13 to 24.

TABLE 2

TABLE 3

In Comparative Examples 1 to 12, the leaching method was performed after the conventional high temperature roasting. When the reaction temperature was reacted at a high temperature of 200 ° C. or higher for 3 hours and leached under shaking conditions, the extraction rate was 46% or less.

Comparative Examples 13 to 24 were extraction processes in which coal ash was shaken at room temperature (25 ° C.) for 3 hours, and did not go through a microwave irradiation step. In Comparative Example 19, which showed the maximum lithium extraction rate, the yield was not good as 46%.

This Mark contained in coal ash light _{[Ca 0 .922 Li 0 .452 Al} 2 Si 2 O 10 .02] (Margarite) in order to extract the lithium in the crystal which is bonded to the high extraction rate, using an extraction solvent at room temperature In addition to the primary extraction reaction, it can be confirmed that the heating by the microwave irradiation method is required.

If the concentration of sulfuric acid used for lithium extraction is 0.1N (Examples 1 to 3) when introducing a secondary extraction process at 90 ° C. for 30 minutes through microwave irradiation after the first shaking extraction process at room temperature for 3 hours (Examples 1 to 3), the extraction rate of lithium is 50-59%, 0.5 N (Examples 4-6) The extraction rate of lithium is 65-75%, 1.0 N (Examples 7-9) 73-96%, 2.0N (Examples 10- 12) The extraction rate is 68 ~ 89%. Therefore, in order to secure a lithium extraction rate of 50% or more, a reaction condition of irradiating with a first microwave at room temperature and a second microwave using sulfuric acid having a concentration of 0.1 N is essential. In order to secure an extraction rate of 65% or more, 0.5N to It is preferable to use sulfuric acid having a concentration of 2.0 N as the extraction solvent.

Furthermore, it can be seen that the solid-liquid ratio, which is the ratio of coal ash and sulfuric acid as the extraction solvent, is excellent in the extraction ratio when 0.05 to 0.50 g / mL, and the highest extraction ratio is obtained when the 1.0N sulfuric acid and the solid-liquid ratio are 0.05g / mL. can do.

Further, by further connecting the circulation pipe 12 to the device for extracting lithium from the coal ash, it is possible to concentrate the lithium by cyclically transferring a solution containing lithium to the reactor, as shown in Figure 7 Since the lithium can be concentrated to 200 ppm or more, which is a concentration for crystallizing lithium at least 9 times of recycling, it can be seen that it is preferable to circulate the solution containing lithium using the circulation pipe 12.

The embodiments presented above are exemplary and those skilled in the art may make various modifications and modifications to the embodiments presented without departing from the spirit of the present invention. Such modifications and variations are not intended to limit the scope of the invention.

Claims (12)

1. Reacting the coal ash and the extraction solvent; And

   Irradiating microwave to obtain a solution containing lithium.
2. The method according to claim 1, wherein the fly ash is characterized in that it comprises the margarite _{[Ca 0 .922 Li 0 .452 Al} 2 Si 2 O 10 .02] crystal, lithium extraction from the fly ash.
3. The method of claim 1, wherein the extraction solvent comprises 0.1 to 2.0 N sulfuric acid.
4. The method of claim 3, wherein the extraction solvent further comprises nitric acid or hydrochloric acid.
5. The method of claim 1, wherein the step of reacting the coal ash and the extraction solvent is characterized in that the reaction at room temperature shaking conditions.
6. The method of extracting lithium from coal ash according to claim 1, wherein the step of irradiating the microwaves is performed at 60 to 90 ° C in a bath condition.
7. The method of extracting lithium from coal ash according to claim 1, wherein the coal ash and the extraction solvent are reacted at a solid-liquid ratio of 0.05 to 0.50 g / mL.
8. The method of claim 1, further comprising generating a lithium salt by performing a salt generating reaction on the lithium-containing solution.
9. Coal ash feeder;

   Extraction solvent supply apparatus; And

   Lithium from coal ash comprising a microwave extraction device for reacting the coal ash and the extraction solvent supplied from the coal ash feed device and the extraction solvent supply device, and irradiated microwaves to the reacted coal ash and extract solvent to form a solution containing lithium Device to extract it.
10. 10. The method of claim 9, further comprising an extraction solvent mixing device for diluting the extraction solvent supplied from the extraction solvent supply device and supplying the diluted extraction solvent to the microwave extraction device. Device.
11. The apparatus of claim 10, further comprising a circulation pipe for circulating the solution containing lithium to the extraction solvent mixing device.
12. 10. The apparatus of claim 9, further comprising a crystallization reaction device that generates a lithium salt by performing a salt formation reaction on the solution containing lithium.

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