Method for treating lithium-containing substance, and, device for treating lithium-containing substance

Abstract

To provide a method and device for processing lithium inclusions capable of recovering lithium from a lithium inclusion with high purity.SOLUTION: A method for treating lithium-containing substance comprises: a leaching step S01 in which a lithium-containing substance is immersed in an acidic solution to leach lithium into an acidic, thereby obtaining solution to a lithium leachate, heavy metals and a first fluorine precipitation; a heavy metal and first fluorine precipitation step S02 in which a first calcium compound is added to the lithium leachate to produce metal hydroxide precipitates and precipitates of fluorine; a first solid-liquid separation step S03 in which the precipitated metal hydroxide precipitate and fluorine-containing precipitate are removed from the lithium leachate; a second fluorine precipitating step S04 in which a second calcium compound is added to the lithium leachate from which the precipitates have been removed, to precipitate dissolved fluorine; and a second solid-liquid separation step S05 in which the precipitated dissolved fluorine and unreacted second calcium compound are removed from the lithium leachate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for treating a lithium-containing material and an apparatus for treating a lithium-containing material. [Background technology]

[0002] 2. Description of the Related Art In recent years, lithium has been recovered and reused from lithium-containing materials such as crushed lithium-ion batteries.

[0003] As a method for recovering lithium from lithium-containing materials, a method is known in which lithium-ion battery waste is roasted to obtain battery slag, which is then immersed in an acidic solution to leach lithium into the acidic solution, and lithium is recovered from the resulting lithium leachate. The liquid from which lithium has been leached also contains metals other than lithium, such as cobalt and aluminum, but by adding an alkali such as sodium hydroxide or calcium hydroxide and neutralizing it, mainly the metals other than lithium are precipitated, and the lithium solution can be separated from the other substances by further solid-liquid separation (Patent Document 1).

[0004] Also, as a method for separating lithium from a lithium aqueous solution containing 200 mg / L or more of lithium, 20 mg / L or more of fluorine, and having a pH of 10.5 or more, a method is known in which calcium hydroxide is added to the lithium aqueous solution, the fluorine contained in the lithium aqueous solution is solidified, and the solidified fluorine is removed to obtain a lithium aqueous solution from which the fluorine has been removed. In this method, carbon dioxide is further added to the lithium aqueous solution to solidify the remaining calcium, and the solidified calcium is removed to obtain a lithium aqueous solution from which the fluorine and calcium have been removed (Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6998241 [Patent Document 2] Patent No. 6869444 Summary of the Invention [Problem to be solved by the invention]

[0006] However, as shown in Patent Document 1, if an alkaline agent such as sodium hydroxide is added to the lithium aqueous solution to neutralize the lithium leachate, it becomes difficult to separate the sodium ions and lithium ions, making it impossible to recover a high-purity lithium compound. Furthermore, as shown in Patent Document 2, a single-stage treatment for removing fluorine does not sufficiently remove fluorine, and a lithium compound with a purity suitable for reuse cannot be obtained.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a method and apparatus for treating a lithium-containing material that can recover lithium at high purity from the lithium-containing material. [Means for solving the problem]

[0008] In order to solve the above problems, a method for treating a lithium-containing material according to a first aspect of the present invention includes a leaching step of adding an acidic solution containing an inorganic acid to a lithium-containing material to cause lithium to be leached into the acidic solution, a heavy metal and first fluorine precipitation step of adding a first calcium compound to the lithium leachate obtained in the leaching step to cause heavy metal ions to be precipitated as hydroxides and fluorine to be precipitated, a first solid-liquid separation step of separating the hydroxides of the heavy metal ions and the fluorine precipitate from the lithium leachate after the heavy metal and first fluorine precipitation step, a second fluorine precipitation step of adding a second calcium compound to the lithium leachate after the first solid-liquid separation step to cause dissolved fluorine to be precipitated, and a second solid-liquid separation step of separating the precipitate of dissolved fluorine and the unreacted second calcium compound from the lithium leachate after the second fluorine precipitation step to obtain a lithium-containing liquid.

[0009] According to the method for treating a lithium-containing material of the first aspect of the present invention, in the heavy metal and first fluorine precipitation step, a first calcium compound is added to precipitate heavy metals such as cobalt, nickel, manganese, and fluorine dissolved in the lithium leachate, and the precipitate is separated from the lithium leachate in the first solid-liquid separation step. As a result, a lithium leachate having high lithium purity from which heavy metals and fluorine have been removed can be obtained. Furthermore, in the second fluorine precipitation step, a second calcium compound is added to the lithium leaching solution to precipitate heavy metals and dissolved fluorine that could not be completely removed in the first fluorine precipitation step and the first solid-liquid separation step, and in the second solid-liquid separation step, the precipitate of dissolved fluorine that has been precipitated and the unreacted second calcium compound added in the second fluorine precipitation step are removed. This makes it possible to remove an amount of fluorine that cannot be completely removed by a single-stage fluorine removal process, and to obtain a lithium-containing solution with a higher lithium purity than in the past. In both precipitation steps, a calcium compound is used to adjust the pH of the lithium leaching solution, which makes it possible to reduce the amount of sodium contaminating the lithium leaching solution compared to the case in which sodium hydroxide (a sodium compound) is used for neutralization as described in Patent Document 1.

[0010] The method for treating a lithium-containing material of a second aspect of the present invention is characterized in that, in the method for treating a lithium-containing material of the first aspect, it further comprises, after the second solid-liquid separation step, a calcium precipitation step of adding a soluble carbonate compound to the lithium-containing liquid to precipitate calcium as calcium carbonate, and, after the calcium precipitation step, a third solid-liquid separation step of separating the calcium carbonate from the lithium-containing liquid. According to the method for treating a lithium-containing material of the second aspect of the present invention, calcium ions, which are a part of the calcium compounds added in the first and second fluorine precipitation steps that remain in the lithium leaching solution as dissolved calcium ions, can be separated from the lithium-containing solution as calcium carbonate, making it possible to obtain a lithium-containing solution with an even higher lithium purity.

[0011] The method for treating a lithium-containing material of the third aspect of the present invention is characterized in that, in the method for treating a lithium-containing material of the first or second aspect, the fluorine precipitate and the unreacted second calcium compound separated in the second solid-liquid separation step are used as the first calcium compound in the heavy metal and first fluorine precipitation step. According to the method for treating a lithium-containing material of the third aspect of the present invention, the unreacted second calcium compound recovered in the second solid-liquid separation step is used in the heavy metal and first fluorine precipitation steps, so that the chemical costs can be reduced. In addition, the precipitates generated in the first fluorine precipitation step and the second fluorine precipitation step can be combined, so that the cost of sludge treatment can be reduced.

[0012] A method for treating a lithium-containing material according to a fourth aspect of the present invention is characterized in that, in the method for treating a lithium-containing material according to the second or third aspect, the calcium carbonate separated in the third solid-liquid separation step is used as the second calcium compound in the second fluorine precipitation step. According to the method for treating a lithium-containing material of the fourth aspect of the present invention, the calcium carbonate recovered in the third solid-liquid separation step is used in the second fluorine precipitation step, so that the chemical costs and the amount of sludge can be reduced.

[0013] A method for treating a lithium-containing material according to a fifth aspect of the present invention is characterized in that, in the method for treating a lithium-containing material according to any one of the first to fourth aspects, the solid content containing calcium fluoride separated in the second solid-liquid separation step is used as seed crystals in the second fluorine precipitation step. According to the method for treating a lithium-containing material of the fifth aspect of the present invention, the solid content recovered in the second solid-liquid separation step is used as seed crystals in the second fluorine precipitation step. This increases the solid concentration in the second fluorine precipitation step, thereby making it possible to enhance the fluorine removal efficiency and, in addition, reduce the amount of sludge.

[0014] A method for treating a lithium-containing material according to a sixth aspect of the present invention is characterized in that, in the method for treating a lithium-containing material according to any one of the second to fifth aspects, the calcium carbonate separated in the third solid-liquid separation step is used as seed crystals in the calcium precipitation step. According to the method for treating a lithium-containing material of the sixth aspect of the present invention, the calcium carbonate removed in the third solid-liquid separation step is used as seed crystals in the calcium precipitation step. This increases the solid concentration in the calcium precipitation step, thereby making it possible to enhance the calcium removal efficiency and, in addition, reduce the amount of sludge.

[0015] A seventh aspect of the present invention is a method for treating a lithium-containing material according to any one of the second to sixth aspects, characterized in that in the second fluorine precipitation step, a sodium compound is added after the second calcium compound is added. According to the method for treating lithium-containing material of embodiment 7 of the present invention, the sodium compound is used supplementarily, and as a result, the amount of sodium contaminating the lithium leaching solution can be reduced compared to the case where sodium hydroxide (sodium compound) described in Patent Document 1 is mainly used.

[0016] The method for treating a lithium-containing material of the eighth aspect of the present invention is characterized in that, in the method for treating a lithium-containing material of any one of the first to sixth aspects, a soluble aluminum compound is added in the second fluorine precipitation step. According to the method for treating a lithium-containing material of the eighth aspect of the present invention, the soluble aluminum compound acts as an inorganic flocculant to improve sedimentation properties, making it easier to remove the fluorine precipitate generated in the second fluorine precipitation step. In addition, aluminum hydroxide generated by hydrolysis of soluble aluminum has the effect of adsorbing fluorine, so that a lithium-containing liquid with a higher lithium purity can be obtained.

[0017] A ninth aspect of the present invention is a method for treating a lithium-containing material according to any one of the second to seventh aspects, characterized in that a soluble aluminum compound is added in the calcium precipitation step. According to the method for treating a lithium-containing material of the ninth aspect of the present invention, the action of the soluble aluminum compound as an inorganic flocculant improves separability, making it easier to remove calcium carbonate produced in the calcium precipitation step, and therefore it is possible to obtain a lithium-containing liquid having a higher lithium purity.

[0018] A method for treating a lithium-containing material according to a tenth aspect of the present invention is characterized in that, in the method for treating a lithium-containing material according to any one of the first to eighth aspects, an anionic polymer flocculant is added in the second solid-liquid separation step. According to the method for treating a lithium-containing material of the tenth aspect of the present invention, the sedimentation property is dramatically improved by the polymer flocculant, and the fluorine precipitate and calcium carbonate can be more easily removed in the second solid-liquid separation step, so that a lithium-containing liquid having a higher lithium purity can be obtained.

[0019] The method for treating a lithium-containing material of an eleventh aspect of the present invention is the method for treating a lithium-containing material of any one of the second to ninth aspects, further comprising the step of adding an anionic polymer flocculant in the third solid-liquid separation step. According to the method for treating a lithium-containing material of the eleventh aspect of the present invention, the sedimentation separability is dramatically improved by the polymer flocculant, and calcium carbonate is more easily removed in the third solid-liquid separation step, so that a lithium-containing liquid having a higher lithium purity can be obtained.

[0020] A method for treating a lithium-containing material according to a twelfth aspect of the present invention is the method for treating a lithium-containing material according to any one of the first to tenth aspects, characterized in that in the heavy metal and first fluoride precipitation step, the first calcium compound is added to adjust the pH to within a range of 9 or more and 11 or less. According to the method for treating a lithium-containing material of the twelfth aspect of the present invention, many heavy metal ions can be easily separated as hydroxide precipitates in the heavy metal and first fluorine precipitation steps, and a lithium-containing liquid having high lithium purity can be obtained.

[0021] A method for treating a lithium-containing material according to a thirteenth aspect of the present invention is the method for treating a lithium-containing material according to any one of the first to eleventh aspects, characterized in that in the second fluorine precipitation step, the pH is adjusted to within a range of 6.5 to 8 by adding the second calcium compound. According to the method for treating a lithium-containing material of the thirteenth aspect of the present invention, fluorine is more likely to precipitate in the second fluorine precipitation step, which makes it possible to remove a larger amount of fluorine and obtain a lithium-containing solution having a high lithium purity.

[0022] A method for treating a lithium-containing material according to a fourteenth aspect of the present invention is the method for treating a lithium-containing material according to any one of the second to twelfth aspects, characterized in that in the calcium precipitation step, the pH is adjusted to within a range of 9 to 11 by adding the soluble carbonate compound. According to the method for treating a lithium-containing material of the fourteenth aspect of the present invention, calcium carbonate is easily precipitated in the calcium precipitation step. Therefore, it becomes possible to remove more calcium, and it is possible to obtain a lithium-containing solution having a high lithium purity. In addition, it is possible to prevent lithium from precipitating as carbonate in the calcium precipitation step, and to prevent a decrease in the lithium concentration of the lithium-containing solution.

[0023] A fifteenth aspect of the present invention is a method for treating a lithium-containing material according to any one of the first to thirteenth aspects, wherein the lithium-containing material is a fine powder obtained by pulverizing a lithium ion battery. According to the method for treating lithium-containing material of the fifteenth aspect of the present invention, high-purity lithium can be recovered from waste lithium-ion batteries.

[0024] A lithium-containing material treatment apparatus according to a sixteenth aspect of the present invention is characterized in that it includes a leaching tank for adding an acidic solution containing an inorganic acid to a lithium-containing material to cause lithium to be leached into the acidic solution to generate a lithium leachate, a heavy metal and first fluorine precipitation tank for adding a first calcium compound to the lithium leachate to precipitate heavy metal ions as hydroxides and to precipitate fluorine, a first solid-liquid separator for separating the hydroxides of the heavy metal ions and the fluorine precipitate from the lithium leachate, a second fluorine precipitation tank for adding a second calcium compound to the lithium leachate to precipitate dissolved fluorine, and a second solid-liquid separator for separating the precipitate of dissolved fluorine and the unreacted second calcium compound from the lithium leachate to obtain a lithium-containing liquid.

[0025] According to the lithium-containing material treatment device of the sixteenth aspect of the present invention, in the heavy metal and first fluorine precipitation tank, the first calcium compound is added to precipitate heavy metals such as cobalt, nickel, manganese, and fluorine dissolved in the lithium leachate, and the precipitates are removed in the first solid-liquid separator. As a result, a lithium leachate having a high lithium purity from which heavy metals and fluorine have been removed can be obtained. Furthermore, in the second fluorine precipitation tank, the second calcium compound is added to the lithium leachate to precipitate heavy metals and dissolved fluorine that could not be removed in the first fluorine precipitation tank and the first solid-liquid separator, and the precipitate of dissolved fluorine that has been precipitated and the unreacted second calcium compound added in the second fluorine precipitation tank are removed in the second solid-liquid separator. This makes it possible to remove an amount of fluorine that cannot be removed in a one-stage fluorine removal process, and to obtain a lithium-containing solution having a higher lithium purity.

[0026] The lithium-containing material treatment apparatus of aspect 17 of the present invention is characterized in that, in the lithium-containing material treatment apparatus of aspect 15, it further includes a calcium precipitation tank in which a soluble carbonate compound is added to the lithium-containing liquid to precipitate calcium as calcium carbonate, and a third solid-liquid separator in which the calcium carbonate is separated from the lithium-containing liquid. According to the lithium-containing material treatment device of the seventeenth aspect of the present invention, the second calcium compound added in the second fluorine precipitation tank is removed, so that a lithium-containing liquid having a higher lithium purity can be obtained. Effect of the Invention

[0027] According to the present invention, it is possible to provide a method and an apparatus for treating a lithium-containing material that can recover lithium at high purity from the lithium-containing material. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a flow diagram showing a method for treating a lithium-containing material according to one embodiment of the present invention. [Diagram 2] FIG. 1 is a block diagram showing a treatment device for lithium-containing material according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram showing the results of powder X-ray diffraction of a precipitate formed by adding 25% NaOH to a lithium-containing liquid and stirring the liquid in an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, a lithium-containing material processing method and processing device according to an embodiment of the present invention will be described with reference to the drawings. Note that each embodiment shown below is specifically described to better understand the gist of the invention, and does not limit the present invention unless otherwise specified.

[0030] FIG. 1 is a flow diagram showing a method for treating a lithium-containing material according to one embodiment of the present invention. As shown in FIG. 1, the method for treating a lithium-containing material of the present embodiment includes a leaching step S01, a heavy metal and first fluorine precipitation step S02, a first solid-liquid separation step S03, a second fluorine precipitation step S04, a second solid-liquid separation step S05, a calcium precipitation step S06, and a third solid-liquid separation step S07.

[0031] (Leaching process S01) In the leaching step S01, a lithium-containing material such as crushed lithium-ion battery material is immersed in an acidic solution to leach lithium into the acidic solution, thereby obtaining a lithium leachate. As the acidic solution, for example, an inorganic acid such as hydrochloric acid, sulfuric acid, or nitric acid can be used alone or in combination. In this embodiment, sulfuric acid is used as the acid. In this embodiment, the lithium-containing material is mixed with sulfuric acid and stirred for 60 minutes to dissolve the lithium in the lithium-containing material, thereby obtaining a lithium leachate.

[0032] The pH of the lithium leachate is not particularly limited, and is, for example, 1 to 2. Metals other than lithium, fluorine, etc. are also leached into the leachate. The metals contained in the leachate vary depending on the lithium-containing material used, but examples of the metals include cobalt, nickel, manganese, iron, aluminum, etc., which are used as positive electrode active materials, and copper, aluminum, iron, etc., which are used as battery current collectors and exterior materials.

[0033] (Heavy metal and first fluoride precipitation step S02) In the heavy metal and first fluorine precipitation step S02, a first calcium compound is added to the lithium leachate obtained in the leaching step S01 to generate a metal hydroxide precipitate and a fluorine precipitate (e.g., calcium fluoride). The first calcium compound is added, for example, while stirring the lithium leachate. The first calcium compound is not particularly limited as long as it is basic, and solid calcium compounds such as calcium carbonate, calcium hydroxide, calcium oxide, or a mixture thereof can be used. The pH of the lithium leachate when generating the metal hydroxide and calcium fluoride precipitate is adjusted to 8.0 to 12.0. The pH is preferably 9.0 to 11.0, more preferably 9.5 to 10.5, and particularly preferably 10.0, because the heavy metal ions are easily separated as hydroxide precipitates, a lithium leachate with high purity can be obtained, and the amount of calcium compound added can be reduced to reduce chemical costs. As a result, the heavy metal ions are precipitated as metal hydroxides, and the fluoride ions are precipitated as calcium fluoride. Here, heavy metals refer to metals with a specific gravity of 4.0 g / cm3 or more, including, for example, nickel, cobalt, manganese, iron, titanium, zinc, and copper. Other compounds may also precipitate, such as compounds of aluminum and silicon.

[0034] (1st solid-liquid separation step S03) In the first solid-liquid separation step S03, the heavy metals and the metal hydroxide precipitates and fluorine precipitates precipitated in the first fluorine precipitation step S02 are removed from the lithium leaching solution. As a method for removing the precipitates, a solid-liquid separation method such as a gravity settling separation method, a centrifugal separation method, or a filter cloth filtration method such as a filter press can be used.

[0035] (Second fluorine precipitation step S04) In the second fluorine precipitation step S04, a second calcium compound is added to the lithium leachate from which the precipitate has been removed in the first solid-liquid separation step S03 to precipitate the dissolved fluorine. The second calcium compound is not particularly limited as long as it is a basic calcium compound capable of controlling the pH to 5.0 to 9.0, and for example, solid calcium compounds such as calcium carbonate, calcium hydroxide, calcium oxide, or a mixture thereof can be used. The pH of the lithium leachate when generating a precipitate of dissolved fluorine (for example, calcium fluoride) is adjusted to 5.0 or less by first adding aluminum sulfate, and then adding a second calcium compound to adjust the pH to 5.0 to 9.0. Since calcium fluoride is easily precipitated and a lithium leachate with even higher purity is obtained, the pH is preferably 6.5 to 8.0, more preferably 7.0 to 7.5, and particularly preferably 7.0. This allows the heavy metals and dissolved fluorine compounds that could not be completely removed in the first fluorine precipitation step S02 and the first solid-liquid separation step S03 to be precipitated as calcium fluoride. Note that a part of the unreacted second calcium compound precipitates together with calcium fluoride.

[0036] In the second fluorine precipitation step S04, a sodium compound may be added after the addition of the second calcium compound. If only a calcium compound is added, it takes a long time until the pH is stabilized at the target pH, but by adding the sodium compound after the calcium compound, the pH can be stabilized at the target pH quickly.

[0037] In the second fluorine precipitation step S04, an inorganic flocculant may be added to the lithium leachate. The inorganic flocculant improves sedimentation properties, and the precipitate of dissolved fluorine and the unreacted second calcium compound are more easily separated in the second solid-liquid separation step S05 described below, so that a lithium-containing solution with a higher lithium purity can be obtained. As the inorganic flocculant, for example, a commercially available soluble aluminum compound such as aluminum sulfate (aluminum sulfate) or polyaluminum chloride (PAC) can be used. In addition, aluminum hydroxide produced by hydrolysis of soluble aluminum has the effect of adsorbing fluorine, so that a lithium-containing solution with a higher lithium purity can be obtained.

[0038] (Second solid-liquid separation step S05) In the second solid-liquid separation step S05, the precipitate of dissolved fluorine precipitated in the second fluorine precipitation step S04 and the unreacted second calcium compound are removed from the lithium leaching solution to obtain a lithium-containing solution. As a method for removing the precipitate, a solid-liquid separation method such as a gravity settling separation method, a centrifugal separation method, or a filter cloth filtration method such as a filter press can be used.

[0039] In the second solid-liquid separation step S05, a polymer flocculant may be added. The polymer flocculant promotes the formation of flocs, dramatically improving sedimentation properties, and making it easier to separate the precipitate of dissolved fluorine and the unreacted second calcium compound, thereby obtaining a lithium-containing liquid with a higher lithium purity. As the polymer flocculant, a polymer flocculant used in general water treatment, for example, an anionic polymer flocculant whose main component is polyacrylamide, may be used.

[0040] (Calcium precipitation step S06) In the calcium precipitation step S06, a soluble carbonate compound is added to the lithium-containing liquid after removing the precipitate in the second solid-liquid separation step S05, and the dissolved calcium is precipitated as calcium carbonate. The pH of the lithium-containing liquid when the calcium carbonate precipitate is generated is adjusted to 8 to 12. The pH is preferably 9 to 11, more preferably 9.5 to 10.5, and particularly preferably 10.0, because calcium carbonate is easily generated, a lithium-containing liquid with high purity can be obtained, and lithium can be prevented from precipitating as a carbonate salt, and the lithium concentration of the lithium-containing liquid can be prevented from decreasing. As the soluble carbonate compound, for example, sodium carbonate or sodium hydrogen carbonate can be used as a solution or powder. Carbon dioxide gas can also be blown into the reaction tank of the calcium precipitation step S06 to solubilize the dissolved calcium, thereby allowing it to react with the dissolved calcium.

[0041] In the calcium precipitation step S06, an inorganic flocculant may be added to the lithium-containing liquid. The inorganic flocculant improves sedimentation properties, making it easier to remove calcium carbonate precipitate in the third solid-liquid separation step S07 described below, thereby obtaining a lithium-containing liquid with a higher lithium purity. As the inorganic flocculant, for example, a commercially available soluble aluminum compound such as aluminum sulfate (aluminum sulfate) or polyaluminum chloride (PAC) can be used.

[0042] (Third solid-liquid separation step S07) In the third solid-liquid separation step S07, the calcium carbonate precipitate precipitated in the calcium precipitation step S06 is removed from the lithium-containing liquid. As a method for removing the precipitate, a solid-liquid separation method such as a gravity settling separation method, a centrifugal separation method, or a filter cloth filtration method such as a filter press can be used.

[0043] In the third solid-liquid separation step S07, a polymer flocculant may be added. The polymer flocculant dramatically improves sedimentation properties, making it easier to separate calcium carbonate precipitate, and thus a lithium-containing solution with higher lithium purity can be obtained. As the polymer flocculant, a polymer flocculant used in general water treatment, for example, an anionic polymer flocculant whose main component is polyacrylamide, can be used.

[0044] Here, in the treatment of lithium-containing materials, it may be necessary to reduce the cost of chemicals and the amount of sludge generated. In that case, the method may include at least one of a first recycling step S08 in which the precipitate of dissolved fluorine separated and recovered in the second solid-liquid separation step S05 and the unreacted second calcium compound are used as the heavy metal and the first calcium compound to be added in the first fluorine precipitation step S02, a second recycling step S09 in which the calcium carbonate precipitate removed in the third solid-liquid separation step S07 is used as the second calcium compound to be added in the second fluorine precipitation step S04, a third recycling step S10 in which the solid content removed in the second solid-liquid separation step S05 is used as seed crystals in the second fluorine precipitation step S04, and a fourth recycling step S11 in which the calcium carbonate precipitate removed in the third solid-liquid separation step S07 is used as seed crystals in the calcium precipitation step S06.

[0045] (1st reuse step S08) In the first reuse step S08, the precipitate of dissolved fluorine and the unreacted second calcium compound removed from the lithium-containing liquid in the second solid-liquid separation step S05 (the precipitate and the unreacted substance are collectively referred to as the solid content in the description of this step) are used as the first calcium compound to be added in the heavy metal and first fluorine precipitation step S02 to precipitate metal ions and fluoride ions. The solid content may be added entirely in the heavy metal and first fluorine precipitation step S02, or only a part of it may be added. Also, only the solid content may be added in the heavy metal and first fluorine precipitation step S02, or other calcium compounds may be added in addition to the solid content. By reusing the unreacted second calcium compound in this step, the cost of chemicals can be reduced. In addition, since the precipitates generated in the first fluorine precipitation step and the second fluorine precipitation step can be combined, the cost of sludge treatment can be reduced.

[0046] (Second reuse process S09) In the second reuse step S09, the calcium carbonate precipitate removed from the lithium-containing liquid in the third solid-liquid separation step S07 is used as a second calcium compound to be added in the second fluorine precipitation step S04 to precipitate dissolved fluoride ions. The calcium carbonate precipitate removed in the third solid-liquid separation step S07 may be added in its entirety in the second fluorine precipitation step S04, or only a portion of it may be added. In addition, only the calcium carbonate precipitate removed in the third solid-liquid separation step S07 may be added in the second fluorine precipitation step S04, or other calcium compounds may be added in addition to the calcium carbonate precipitate removed in the third solid-liquid separation step S07. By reusing the calcium carbonate precipitate that would otherwise be discarded in this step, it is possible to reduce chemical costs and the amount of sludge generated.

[0047] (Third reuse step S10) In the third reuse step S10, the solid content removed from the lithium-containing liquid in the second solid-liquid separation step S05 is added to the lithium leaching solution to be used as seed crystals in the second fluorine precipitation step S04. The solid content separated in the second solid-liquid separation step S05 may be added in its entirety to the second fluorine precipitation step S04, or only a portion of it may be added. Since the solid content is used as seed crystals in the second fluorine precipitation step, the solid concentration in the second fluorine precipitation step increases, making it possible to increase the fluorine removal efficiency and, in addition, reduce the amount of sludge.

[0048] (4th reuse step S11) In the fourth reuse step S11, the calcium carbonate precipitate removed from the lithium-containing liquid in the third solid-liquid separation step S07 is added to the lithium-containing liquid to be used as seed crystals in the calcium precipitation step S06. The calcium carbonate precipitate removed in the third solid-liquid separation step S07 may be added in its entirety to the calcium precipitation step S06, or only a portion of it may be added. By reusing the calcium carbonate precipitate that would otherwise be discarded in this step, the solid concentration in the calcium precipitation step increases, making it possible to increase the calcium removal efficiency and also reduce the amount of sludge.

[0049] The above-described process enables the recovery of high-purity lithium from lithium-containing materials.

[0050] FIG. 2 is a block diagram showing a treatment apparatus for a lithium-containing material according to one embodiment of the present invention. 2, the lithium-containing material treatment device 1 of this embodiment has at least a leaching tank 10, a heavy metal and first fluorine precipitation tank 20, a first solid-liquid separator 30, a second fluorine precipitation tank 40, and a second solid-liquid separator 50. The lithium-containing material treatment device 1 of this embodiment may further have a calcium precipitation tank 60 and a third solid-liquid separator 70.

[0051] The leaching tank 10 of this embodiment is only required to immerse the lithium-containing material in an acidic solution, leach lithium into the acidic solution, and obtain a lithium leachate. The heavy metal and first fluorine precipitation tank 20 is only required to add a first calcium compound to the lithium leachate to generate a metal hydroxide precipitate and a fluorine precipitate. The first solid-liquid separator 30 is only required to remove the metal hydroxide precipitate and the fluorine precipitate from the lithium leachate. The second fluorine precipitation tank 40 is only required to add a second calcium compound to the lithium leachate to precipitate the dissolved fluorine. The second solid-liquid separator 50 is only required to remove the dissolved fluorine precipitate and the unreacted second calcium compound from the lithium leachate to obtain a lithium-containing liquid. The calcium precipitation tank 60 is only required to add a soluble carbonate compound to the lithium-containing liquid to precipitate the dissolved calcium as calcium carbonate. The third solid-liquid separator 70 is only required to remove the calcium carbonate precipitate from the lithium-containing liquid.

[0052] According to the method for treating a lithium-containing material of the present embodiment configured as described above, the leaching step S01, the heavy metal and first fluorine precipitation step S02, and the first solid-liquid separation step S03 are performed to remove metal ions and fluoride ions, and then the second fluorine precipitation step S04 and the second solid-liquid separation step S05 are performed. Thus, the step of removing fluorine is performed in two stages, and therefore it is possible to obtain a lithium-containing liquid having a higher lithium purity than the conventional technique which has only one fluorine removal step.

[0053] Furthermore, by carrying out the calcium precipitation step S06 and the third solid-liquid separation step S07, the calcium added in the second fluorine precipitation step S04 can be removed, so that a lithium-containing liquid having a higher lithium purity can be obtained.

[0054] In this embodiment, when the first reuse step S08 is used, the chemical cost and the amount of sludge can be reduced.

[0055] In this embodiment, when the second reuse step S09 is used, the chemical cost and the amount of sludge can be reduced.

[0056] In the present embodiment, in the case of using the third recycling step S10, the solid concentration of the fluorine precipitate in the lithium leachate increases in the second fluorine precipitation step S04, so that the fluorine removal efficiency can be increased and the amount of sludge can be reduced.

[0057] In the present embodiment, in the case of using the fourth reuse step S11, the solid concentration of calcium carbonate in the lithium-containing liquid increases in the calcium precipitation step S06, so that the calcium removal efficiency can be increased and the amount of sludge can be reduced.

[0058] In the present embodiment, in the case where an inorganic flocculant is added in the second fluorine precipitation step S04, the sedimentation separation property is improved by the inorganic flocculant, and the precipitate of dissolved fluorine and the unreacted second calcium generated in the second fluorine precipitation step S04 are more easily removed, so that a lithium-containing liquid having a higher lithium purity can be obtained.

[0059] In the present embodiment, in the case of a configuration in which an inorganic flocculant is added in the calcium precipitation step S06, the inorganic flocculant improves separability of sedimentation, and the calcium carbonate precipitate generated in the calcium precipitation step S06 becomes easier to remove, so that a lithium-containing liquid with a higher lithium purity can be obtained.

[0060] In the present embodiment, in the case of a configuration in which a polymer flocculant is added in the second solid-liquid separation step S05, the formation of flocculants is promoted by the polymer flocculant, and the sedimentation separability is dramatically improved. In the second solid-liquid separation step S05, the precipitate of dissolved fluorine and the unreacted second calcium are more easily separated, so that a lithium-containing liquid having a higher lithium purity can be obtained.

[0061] In the present embodiment, in the case of a configuration in which a polymer flocculant is added in the third solid-liquid separation step S07, the formation of flocculants is promoted by the polymer flocculant, and the sedimentation separability is dramatically improved. As a result, the calcium carbonate precipitate becomes easier to separate in the third solid-liquid separation step S07, and therefore a lithium-containing liquid having a higher lithium purity can be obtained.

[0062] In the present embodiment, when the pH is adjusted to 9 to 11 when generating the metal hydroxide precipitate and the fluorine precipitate in the heavy metal and first fluorine precipitation step S02, many heavy metal ions are easily separated as hydroxide precipitate in the heavy metal and first fluorine precipitation step S02. Therefore, a lithium-containing liquid with high lithium purity can be obtained.

[0063] In the present embodiment, in the case where the pH is adjusted to 6.5 to 8 when the precipitate of dissolved fluorine is generated in the second fluorine precipitation step S04, the dissolved fluorine is more likely to precipitate in the second fluorine precipitation step S04. Therefore, it becomes possible to remove a larger amount of fluorine, and a lithium-containing liquid having a high lithium purity can be obtained.

[0064] In the present embodiment, in the case where the pH is adjusted to 9 to 11 when calcium carbonate precipitate is generated in the calcium precipitation step S06, calcium carbonate is easily generated in the calcium precipitation step S06. Therefore, it becomes possible to remove more calcium, and a lithium-containing solution having a high lithium purity can be obtained. In addition, it is possible to prevent lithium from precipitating as carbonate in the calcium precipitation step S06, and to prevent a decrease in the lithium concentration of the lithium-containing solution.

[0065] According to the lithium-containing material treatment device of the present embodiment configured as described above, the first calcium compound is added in the heavy metal and first fluorine precipitation tank 20 to precipitate heavy metals such as cobalt, nickel, manganese, and fluorine dissolved in the lithium leachate, and the precipitates are removed in the first solid-liquid separator 30. As a result, a lithium leachate having a high lithium purity from which heavy metals and fluorine have been removed is obtained. Furthermore, in the second fluorine precipitation tank 40, the second calcium compound is added to the lithium leachate to precipitate heavy metals and dissolved fluorine that could not be removed in the first fluorine precipitation tank 20 and the first solid-liquid separator 30, and the precipitate of dissolved fluorine that has been precipitated and the unreacted second calcium compound added in the second fluorine precipitation tank 40 are removed in the second solid-liquid separator 50. This makes it possible to remove an amount of fluorine that cannot be removed by a one-stage fluorine removal process, and to obtain a lithium-containing solution having a higher lithium purity.

[0066] In the present embodiment, in the case of a configuration including the calcium precipitation tank 60 in which a soluble carbonate compound is added to the lithium leaching solution to precipitate calcium as calcium carbonate, and the third solid-liquid separator 70 in which calcium carbonate is separated from the lithium-containing solution, the second calcium compound added in the second fluorine precipitation tank 40 is removed, so that a lithium-containing solution with an even higher lithium purity can be obtained.

[0067] Although the embodiment of the present invention has been described above, the present invention is not limited to this, and can be modified as appropriate without departing from the technical concept of the invention. EXAMPLES

[0068] The results of confirmatory experiments conducted to confirm the effectiveness of the present invention will be described below.

[0069] 80g of the sintered and crushed powder of the lithium-ion battery with the composition in Table 1 was suspended in 320mL of water, 75g of 47% sulfuric acid was added, and the mixture was stirred for 60 minutes to leach lithium and heavy metals, and a lithium leachate was obtained (leaching step S01). The pH of the lithium leachate at this time was 1.8. After that, a 30% suspension was prepared with 30g of calcium hydroxide in the lithium leachate, and 45mL of the suspension was added and stirred (heavy metal and first fluorine precipitation step S02). The pH rose to 11.0. After that, suction filtration was performed to separate the leachate residue and the lithium leachate (first solid-liquid separation step S03). The composition of the sintered and crushed powder of the lithium-ion battery was analyzed by fluorescent X-ray analysis for all components except lithium and fluorine, by ICP emission spectroscopy for lithium, and by ion chromatography for fluorine.

[0070] 1000 mL of the lithium leachate was taken and 2 mL of liquid aluminum sulfate was added as an inorganic flocculant. At this time, the pH of the lithium leachate was 4.6. Furthermore, 10 g of calcium carbonate was added to the lithium leachate as seed crystals. At this time, the pH of the lithium leachate was 6.0. After these were added, 25% sodium hydroxide was further added to adjust the pH to 7.0 and the solution was stirred for 1 hour (second fluorine precipitation step S04). 0.5 mL of a 0.05 mass% solution of polymer flocculant (Diafloc A825B) was added and stirred to obtain a floc-like solid. When the solution was allowed to settle and separated, 950 mL of clear supernatant liquid was obtained in about 2 minutes (second liquid separation step S05).

[0071] After the settling, 950 mL of the supernatant of the lithium-containing solution was taken, and 1.5 mL of liquid aluminum sulfate was added, followed by the addition of calcium carbonate to a concentration of 10 g / L. The pH of the lithium-containing solution at this time was 4.9. When 1.9 g of sodium carbonate was further added, the pH became 8.5 and a white precipitate was formed. Furthermore, 2 mL of 25% NaOH was added to adjust the pH to 10.0, and the solution was stirred for 60 minutes (calcium precipitation step S06). Then, 1.9 mL of a 0.05 mass% solution of a polymer flocculant (Diafloc AP825B) was added, and a floc-like solid was obtained by stirring. After natural settling, 900 mL of clear supernatant was obtained in about 2 minutes (third liquid separation step S07). The composition of the lithium leaching solution and the supernatant obtained in each step were measured by ICP emission spectroscopy, and the results are shown in Table 2.

[0072] [Table 1]

[0073] [Table 2]

[0074] Example 1 150g of sintered and crushed powder of lithium-ion batteries was suspended in 815mL of water, and 91g of 47% sulfuric acid was added and stirred for 60 minutes to leach lithium and heavy metals, obtaining a lithium leachate (leaching process S01). The pH of the lithium leachate at this time was 1.8. After that, a 30% suspension was prepared with 60g of calcium hydroxide in the lithium leachate, and 200mL of the suspension was added and stirred (heavy metal and first fluorine precipitation process S02). The pH rose to 10.8. After that, suction filtration was performed to separate the leachate residue and the lithium leachate (first liquid separation process S03).

[0075] 1000 mL of the lithium leachate was taken and 0.5 mL of liquid aluminum sulfate was added as an inorganic flocculant. At this time, the pH of the lithium leachate was 5.6. Furthermore, 10 g of calcium carbonate was added to the lithium leachate as seed crystals. At this time, the pH of the lithium leachate was 6.0. After these were added, 25% sodium hydroxide was further added to adjust the pH to 6.5 and the mixture was stirred for 1 hour (second fluorine precipitation step S04). 1 mL of a 0.05 mass% solution of a polymer flocculant (Diafloc AP825B) was added and stirred to obtain a floc-like solid. After natural settling and separation, a clear supernatant (950 mL) was obtained in about 2 minutes (second liquid separation step S05). The composition of this supernatant was measured by ICP emission spectroscopy.

[0076] (Examples 2 to 8) In Examples 2 to 8, the amount of liquid aluminum sulfate added in S04 of Example 1 and the pH of the lithium leaching solution when liquid aluminum sulfate, calcium carbonate, and sodium hydroxide were added and stirred were changed to different values ​​(pH 6.0 to 8.5), and the other conditions were the same as those of Example 1.

[0077] Comparative Example 1 In Comparative Example 1, after adding liquid aluminum sulfate in the second fluorine precipitation step S04, calcium carbonate was not added, but 25% sodium hydroxide was added to adjust the pH of the lithium leaching solution to 7.0. The other conditions were the same as those in Examples 1 to 8.

[0078] The experimental results of Examples 1 to 8 and Comparative Example 1 are shown in Table 3. The pH of the lithium leachate in Table 3 is the pH of the lithium leachate when liquid aluminum sulfate, calcium carbonate, and sodium hydroxide were added and stirred in S04. The raw water is the lithium leachate after the first solid-liquid separation step S03.

[0079] [Table 3]

[0080] As shown in Table 3, the fluorine concentration in the lithium-containing solution was lower in Examples 1 to 8 in which calcium carbonate was added than in Comparative Example 1 in which calcium carbonate was not added. This result shows that by performing the fluorine removal process in two stages, a lithium-containing solution having a low fluorine concentration, that is, a high lithium purity, can be obtained. It was also found that when the pH of the lithium leaching solution is 6.5 or more and 8.0 or less, a lithium-containing solution having a lower fluorine concentration can be obtained than when it is outside this range.

[0081] Example 9 950 mL of the supernatant of the lithium-containing liquid after the settling separation in Example 5 was taken, 0.5 mL of liquid aluminum sulfate was added, and 25 mL of the return precipitate (a solid mainly composed of calcium carbonate, recovered in a process described later) was added. The pH of the lithium-containing liquid at this time was 6.2. Furthermore, when 1.0 g of sodium carbonate was added, the pH became 9.5 and a white precipitate was generated. Furthermore, 0.5 mL of 25% NaOH was added to adjust the pH to 10.0 and stirred for 60 minutes (calcium precipitation process S06). Thereafter, 1 mL of a 0.05 mass% solution of a polymer flocculant (DiaFloc AP825B) was added, the pH was adjusted to 10.0, and stirred for 60 minutes to obtain a floc-like solid. When the liquid was separated by natural settling, 970 mL of a clear supernatant was obtained in about 2 minutes (third liquid separation process S07). The supernatant was collected and filtered through a 0.45 μm membrane filter, and the composition was examined by ICP emission spectroscopy. A portion of the solid matter was collected and identified by powder X-ray diffraction and X-ray fluorescence analysis. The results of the powder X-ray diffraction are shown in Figure 3, and the results of the X-ray fluorescence analysis are shown in Table 4. These results indicate that the main component of the solid matter is calcium carbonate.

[0082] [Table 4]

[0083] Example 10 In Example 10, the amount of sodium carbonate added to the lithium-containing liquid after sedimentation and separation in Example 6 was changed from that in Example 9, and the other conditions were the same as those in Example 9. The composition of the supernatant liquid is shown in Table 5.

[0084] [Table 5]

[0085] As shown in Table 5, by adding sodium carbonate and precipitating the dissolved calcium, a lithium-containing solution with a low calcium concentration could be obtained.

[0086] As a result of the above confirmatory experiments, it was confirmed that according to the present invention, lithium can be recovered with high purity from lithium-containing materials. [Explanation of symbols]

[0087] 1. Lithium-containing material processing equipment 10 Leaching tank 20 Heavy metal and first fluoride precipitator tank 30 1st solid-liquid separator 40 Second fluoride settling tank 50 2nd solid-liquid separator 60 Calcium Precipitation Tank 70 Third solid-liquid separator

Claims

1. a leaching step of adding an acidic solution containing an inorganic acid to the lithium-containing material to leach lithium into the acidic solution; a heavy metal and first fluorine precipitation step in which a first calcium compound is added to the lithium leaching solution obtained in the leaching step to precipitate heavy metal ions as hydroxides and also precipitate fluorine; a first solid-liquid separation step of separating hydroxides of the heavy metal ions and the fluorine precipitate from the lithium leachate after the heavy metal and first fluorine precipitation step; a second fluorine precipitation step of adding a second calcium compound to the lithium leachate after the first solid-liquid separation step to precipitate dissolved fluorine; a second solid-liquid separation step of separating the precipitate of dissolved fluorine and the unreacted second calcium compound from the lithium leaching solution after the second fluorine precipitation step to obtain a lithium-containing solution; A method for treating a lithium-containing material, comprising:

2. a calcium precipitation step of adding a soluble carbonate compound to the lithium-containing liquid after the second solid-liquid separation step to precipitate calcium as calcium carbonate; a third solid-liquid separation step of separating the calcium carbonate from the lithium-containing liquid after the calcium precipitation step; The method for treating a lithium-containing material according to claim 1, further comprising:

3. 2. The method for treating a lithium-containing material according to claim 1, wherein the precipitate of dissolved fluorine and the unreacted second calcium compound separated in the second solid-liquid separation step are used as the first calcium compound in the heavy metal and first fluorine precipitation step.

4. 3. The method for treating a lithium-containing material according to claim 2, wherein the calcium carbonate separated in the third solid-liquid separation step is used as the second calcium compound in the second fluorine precipitation step.

5. 2. The method for treating a lithium-containing material according to claim 1, wherein the solid content separated in the second solid-liquid separation step is used as seed crystals in the second fluorine precipitation step.

6. 3. The method for treating a lithium-containing material according to claim 2, wherein the calcium carbonate separated in the third solid-liquid separation step is used as seed crystals in the calcium precipitation step.

7. 2. The method for treating a lithium-containing material according to claim 1, wherein in the second fluorine precipitation step, a sodium compound is added after the second calcium compound is added.

8. 2. The method for treating a lithium-containing material according to claim 1, wherein a soluble aluminum compound is added in the second fluorine precipitation step.

9. 3. The method for treating a lithium-containing material according to claim 2, wherein a soluble aluminum compound is added in the calcium precipitation step.

10. 2. The method for treating a lithium-containing material according to claim 1, wherein an anionic polymer flocculant is added in the second solid-liquid separation step.

11. 3. The method for treating a lithium-containing material according to claim 2, wherein an anionic polymer flocculant is added in the third solid-liquid separation step.

12. 2. The method for treating a lithium-containing material according to claim 1, wherein in the heavy metal and first fluoride precipitating step, the pH is adjusted to within a range of 9 to 11 by adding the first calcium compound.

13. 2. The method for treating a lithium-containing material according to claim 1, wherein in the second fluorine precipitation step, the pH is adjusted to within the range of 6.5 to 8.0 by adding the second calcium compound.

14. 3. The method for treating a lithium-containing material according to claim 2, wherein in the calcium precipitation step, the pH is adjusted to within a range of 9 to 11 by adding the soluble carbonate compound.

15. The method for treating a lithium-containing material according to any one of claims 1 to 14, wherein the lithium-containing material is a fine powder obtained by pulverizing a lithium ion battery.

16. a leaching tank for adding an acidic solution containing an inorganic acid to the lithium-containing material to cause lithium to be leached into the acidic solution and generate a lithium leachate; a heavy metal and first fluorine precipitation tank for adding a first calcium compound to the lithium leachate to precipitate heavy metal ions as hydroxides and to precipitate fluorine; a first solid-liquid separator for separating the hydroxides of the heavy metal ions and the fluorine precipitate from the lithium leachate; a second fluorine precipitation tank for adding a second calcium compound to the lithium leachate to precipitate dissolved fluorine; a second solid-liquid separator for separating the precipitate of dissolved fluorine and the unreacted second calcium compound from the lithium leachate to obtain a lithium-containing liquid; A treatment device for a lithium-containing material comprising:

17. a calcium precipitation tank for adding a soluble carbonate compound to the lithium-containing liquid to precipitate calcium as calcium carbonate; a third solid-liquid separator for separating the calcium carbonate from the lithium-containing liquid; The apparatus for treating lithium-containing material according to claim 16, further comprising:

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