JP7713736B2 - Method for treating fresh and salty water after lithium membrane electrolysis - Google Patents
Method for treating fresh and salty water after lithium membrane electrolysisInfo
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- JP7713736B2 JP7713736B2 JP2023106013A JP2023106013A JP7713736B2 JP 7713736 B2 JP7713736 B2 JP 7713736B2 JP 2023106013 A JP2023106013 A JP 2023106013A JP 2023106013 A JP2023106013 A JP 2023106013A JP 7713736 B2 JP7713736 B2 JP 7713736B2
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- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
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- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Description
本発明は、リチウム膜電解後の淡塩水の処理方法に関する。 The present invention relates to a method for treating fresh saltwater after lithium membrane electrolysis.
近年、リチウムイオン電池の普及に伴い、廃リチウムイオン電池からコバルト、ニッケル、マンガン、リチウム等の有価金属を回収し、当該リチウムイオン電池の材料として再利用する方法が検討されている。 In recent years, with the widespread use of lithium-ion batteries, methods are being investigated for recovering valuable metals such as cobalt, nickel, manganese, and lithium from discarded lithium-ion batteries and reusing them as materials for those batteries.
引用文献１には、廃リチウムイオン電池を前処理して得られた活物質粉を鉱酸にて溶解して少なくともリチウムを含む該活物質の酸溶解液を得る工程と、水酸化リチウムを添加した当該酸溶解液から、リチウムを除く少なくとも１種の金属を溶媒抽出により分離し、当該溶媒抽出の残液として第１のリチウム塩水溶液を得る工程と、イオン交換膜を用いて当該第１のリチウム塩水溶液を膜電解し、水酸化リチウム水溶液と、酸と、当該第１のリチウム塩水溶液よりも希薄な第２のリチウム塩水溶液を得る工程を備える廃リチウムイオン電池からのリチウムの回収システムが開示されている。 Cited Document 1 discloses a system for recovering lithium from used lithium-ion batteries, which includes the steps of: dissolving active material powder obtained by pretreating used lithium-ion batteries in a mineral acid to obtain an acid solution of the active material containing at least lithium; separating at least one metal excluding lithium from the acid solution to which lithium hydroxide has been added by solvent extraction to obtain a first lithium salt aqueous solution as the residue of the solvent extraction; and performing membrane electrolysis of the first lithium salt aqueous solution using an ion exchange membrane to obtain a lithium hydroxide aqueous solution, acid, and a second lithium salt aqueous solution that is more dilute than the first lithium salt aqueous solution.
塩化リチウム水溶液の膜電解において、膜電解で生成する水酸化リチウムの品質悪化、及び設備の劣化防止が希求されるようになってきた。 In membrane electrolysis of lithium chloride aqueous solutions, there is a growing need to prevent deterioration of the quality of the lithium hydroxide produced by membrane electrolysis and deterioration of the equipment.
したがって、本発明が解決しようとする課題は、水酸化リチウムの品質悪化、及び設備の劣化が防止されるリチウム膜電解後の淡塩水の処理方法を提供することである。 Therefore, the problem that the present invention aims to solve is to provide a method for treating fresh brine after lithium membrane electrolysis that prevents deterioration of the quality of lithium hydroxide and deterioration of the equipment.
本発明者らは上記課題に鑑み検討を重ね、塩素酸塩が、塩化リチウム水溶液の膜電解における水酸化リチウムの品質悪化、及び設備の劣化の原因の１つであること、塩素酸塩は陰極室から逆泳動してくる水酸化物イオンによって生成され、蓄積されること、塩化リチウム水溶液の膜電解工程で発生する塩素酸塩を含有するリチウム塩水溶液を膜電解して、塩素酸塩の蓄積を防止できることを見出した。本発明はこれらの知見に基づき完成されるに至ったものである。 The inventors of the present invention have conducted extensive research in light of the above-mentioned problems and have discovered that chlorate is one of the causes of deterioration in the quality of lithium hydroxide and deterioration of equipment during membrane electrolysis of a lithium chloride aqueous solution, that chlorate is generated and accumulates due to hydroxide ions that reverse migrate from the cathode chamber, and that the accumulation of chlorate can be prevented by performing membrane electrolysis on a lithium salt aqueous solution that contains chlorate generated during the membrane electrolysis process of a lithium chloride aqueous solution. The present invention was completed based on these findings.
本発明は、第１の塩化リチウム水溶液を膜電解し、水酸化リチウム水溶液、塩酸、及び当該第１の塩化リチウム水溶液よりも希薄な、塩素酸塩を含有する第２の塩化リチウム水溶液を得る第１の膜電解工程、及び、当該塩素酸塩を含有する第２の塩化リチウム水溶液を膜電解する第２の膜電解工程を含む、リチウム膜電解後の淡塩水の処理方法に関する。 The present invention relates to a method for treating fresh brine after lithium membrane electrolysis, comprising: a first membrane electrolysis step of subjecting a first lithium chloride aqueous solution to membrane electrolysis to obtain a second lithium chloride aqueous solution containing a lithium hydroxide aqueous solution, hydrochloric acid , and a chlorate salt that is more dilute than the first lithium chloride aqueous solution; and a second membrane electrolysis step of subjecting the second lithium chloride aqueous solution containing the chlorate salt to membrane electrolysis.
前記リチウム膜電解後の淡塩水の処理方法は、好ましくは、リチウムを含む固体を塩酸で溶解して酸溶解液を得る酸溶解工程、当該酸溶解液に水酸化リチウムを添加する中和工程、及び、当該中和工程で得られた酸溶解液から、リチウムを除く少なくとも１種の金属を溶媒抽出により分離し、当該溶媒抽出の残液として前記第１の塩化リチウム水溶液を得る溶媒抽出工程を更に含み、前記水酸化リチウム水溶液の一部を、当該中和工程、及び当該溶媒抽出工程からなる群から選択される少なくとも１つで使用される水酸化リチウムとして用い、前記第１の膜電解工程で発生する塩酸を当該酸溶解工程で用いる。
前記リチウム膜電解後の淡塩水の処理方法は、好ましくは、前記第２の塩化リチウム水溶液の一部と前記第１の塩化リチウム水溶液を混合して濃縮し第３の塩化リチウム水溶液を得る混合濃縮工程を更に含む。
前記第３の塩化リチウム水溶液は、好ましくは、イオン交換膜を用いて膜電解され、得られた塩素と水素とを反応させて生成する塩酸は前記酸溶解工程に用いられる。
前記第１の膜電解工程、及び前記第２の膜電解工程からなる群から選択される少なくとも１つに用いる電力は、好ましくは再生可能エネルギーによって得られた電力を含む。
前記再生可能エネルギーによって得られた電力は、好ましくは太陽光発電、風力発電、水力発明、及びバイオマス発電からなる群から選択される少なくとも１つによって得られた電力を含む。
好ましくは、前記第２の膜電解工程で塩素酸塩の一部は分解され、前記第２の膜電解工程に付された塩素酸塩を含有する塩化リチウム水溶液は前記第１の膜電解工程に戻される。
The method for treating fresh brine after lithium membrane electrolysis preferably further comprises an acid dissolution step of dissolving a lithium-containing solid with hydrochloric acid to obtain an acid solution, a neutralization step of adding lithium hydroxide to the acid solution, and a solvent extraction step of separating at least one metal excluding lithium from the acid solution obtained in the neutralization step by solvent extraction and obtaining the first aqueous lithium chloride solution as a residue of the solvent extraction, wherein a part of the aqueous lithium hydroxide solution is used as the lithium hydroxide to be used in at least one step selected from the group consisting of the neutralization step and the solvent extraction step, and hydrochloric acid generated in the first membrane electrolysis step is used in the acid dissolution step.
The method for treating fresh brine after lithium membrane electrolysis preferably further includes a mixing and concentrating step of mixing a part of the second aqueous lithium chloride solution with the first aqueous lithium chloride solution and concentrating the mixture to obtain a third aqueous lithium chloride solution.
The third lithium chloride aqueous solution is preferably subjected to membrane electrolysis using an ion exchange membrane, and the resulting chlorine is reacted with hydrogen to produce hydrochloric acid, which is used in the acid dissolution step.
The electric power used in at least one selected from the group consisting of the first membrane electrolysis step and the second membrane electrolysis step preferably includes electric power obtained from renewable energy.
The electricity obtained by renewable energy preferably includes electricity obtained by at least one selected from the group consisting of solar power generation, wind power generation, hydropower generation, and biomass power generation.
Preferably, a portion of the chlorate is decomposed in the second membrane electrolysis step, and the chlorate-containing lithium chloride aqueous solution subjected to the second membrane electrolysis step is returned to the first membrane electrolysis step.
本発明のリチウム膜電解後の淡塩水の処理方法は、水酸化リチウムの品質悪化、及び設備の劣化が防止されるリチウム膜電解後の淡塩水の処理方法を提供する。 The present invention provides a method for treating fresh brine after lithium membrane electrolysis that prevents deterioration of the quality of lithium hydroxide and deterioration of equipment.
本発明について更に詳細に説明する。
なお、図面の説明において同一の要素には同一の符号を付し、重複する説明を省略する。また、図面の寸法比率は、説明の都合上誇張されており、実際の比率とは異なる場合がある。
The present invention will now be described in further detail.
In the description of the drawings, the same elements are denoted by the same reference numerals, and duplicate explanations will be omitted. Also, the dimensional proportions in the drawings are exaggerated for the convenience of explanation and may differ from the actual proportions.
添付の図面を参照しながら本発明の実施形態について更に詳しく説明する。
図１に示すように、実施形態のリチウム膜電解後の淡塩水の処理方法（図１）は、リチウム含有物１を出発物質としてよい。前記リチウム含有物１は活物質粉であってよい。
The embodiments of the present invention will be described in more detail with reference to the accompanying drawings.
As shown in Fig. 1, the method for treating fresh saltwater after lithium membrane electrolysis according to the embodiment (Fig. 1) may use a lithium-containing material 1 as a starting material. The lithium-containing material 1 may be an active material powder.
前記活物質粉について説明する。廃リチウムイオン電池が電池製品としての寿命が消尽した使用済みのリチウムイオン電池、又は、製造工程で不良品等として廃棄されたリチウムイオン電池である場合、まず、放電処理を行う。放電処理は抵抗放電など、安全性の高い種々の方法が採用され得る。放電により残留している電荷を全て放電させ、次いで、該廃リチウムイオン電池の筐体に開口部を形成した後、例えば、１００～８００℃の範囲の温度で加熱処理（焙焼）した後、ないし加熱処理せずにハンマーミル、ジョークラッシャー等の粉砕機で粉砕し、前記廃リチウムイオン電池を構成する筐体、集電体等を篩分けにより除去（分級）することにより、前記活物質粉を得ることができる。あるいは、前記放電処理後の前記廃リチウムイオン電池を前記粉砕機で粉砕し、前記筐体、集電体等を篩分けにより除去した後、前記範囲の温度で加熱処理することにより、前記活物質粉を得るようにしてもよい。 The active material powder will now be described. When the used lithium-ion batteries are used lithium-ion batteries whose battery life as a battery product has expired or lithium-ion batteries discarded as defective products during the manufacturing process, they are first subjected to a discharge treatment. A variety of highly safe methods, such as resistive discharge, can be used for the discharge treatment. After discharging all remaining charge, an opening is formed in the casing of the used lithium-ion battery. The battery is then heat-treated (roasted) at a temperature ranging from 100 to 800°C, for example, or pulverized in a pulverizer such as a hammer mill or jaw crusher without being heat-treated. The casing, current collector, and other components of the used lithium-ion battery are then removed by sieving (classification), thereby obtaining the active material powder. Alternatively, the used lithium-ion batteries after the discharge treatment can be pulverized in the pulverizer, the casing, current collector, and other components are removed by sieving, and the active material powder can be obtained by heat-treating the battery at a temperature within the range specified above.
前記廃リチウムイオン電池が、製造工程において製品化に用いられた残余の正極材料等である場合、前記放電処理及び開口部の形成を行わず、前記範囲の温度で加熱処理した後、ないし加熱処理せずに前記粉砕機で粉砕し、集電体等を篩分けにより除去して前記活物質粉を得るようにしてもよい。さらに前記廃リチウムイオン電池を前記粉砕機で粉砕し、集電体等を篩分けにより除去した後に前記範囲の温度で加熱処理して、ないし加熱処理せずに活物質粉を得るようにしてもよい。 If the used lithium-ion batteries are residual positive electrode materials used in commercialization during the manufacturing process, they may be pulverized in the pulverizer after being heat-treated at a temperature within the above range or without being heat-treated, without being subjected to the discharge treatment or formation of openings, and the active material powder may be obtained by removing the current collectors and other materials by sieving. Furthermore, the used lithium-ion batteries may be pulverized in the pulverizer, and the current collectors and other materials may be removed by sieving, after which they may be heat-treated at a temperature within the above range or without being heat-treated, to obtain the active material powder.
さらに前記リチウム含有物１は、リチウムとアルミニウムを含むケイ酸塩鉱物の一種であるスポジュメンであってもよい。 Furthermore, the lithium-containing material 1 may be spodumene, a type of silicate mineral that contains lithium and aluminum.
＜酸溶解工程＞
実施形態では、次に、ＳＴＥＰ１で前記リチウム含有物１を塩酸に溶解して、少なくとも前記リチウム含有物１の酸溶解液を得る。前記リチウム含有物１は、前記リチウムの他に、鉄、アルミニウム、マンガン、コバルト、ニッケル等の有価金属を含んでいる場合がある。
<Acid dissolution process>
In the embodiment, next, in STEP 1, the lithium-containing material 1 is dissolved in hydrochloric acid to obtain at least an acid solution of the lithium-containing material 1. The lithium-containing material 1 may contain, in addition to lithium, valuable metals such as iron, aluminum, manganese, cobalt, and nickel.
＜中和工程＞
実施形態では、前記酸溶解液は、次に、ＳＴＥＰ２で水酸化リチウム（ＬｉＯＨ）が添加されることにより中和される。
<Neutralization process>
In an embodiment, the acid solution is then neutralized in STEP 2 by adding lithium hydroxide (LiOH).
＜抽出工程＞
前記中和後の前記酸溶解液は、次に、ＳＴＥＰ３で溶媒抽出に供せられる。前記溶媒抽出では、前記有価金属のうち、リチウムを除く、マンガン、コバルト、ニッケルが各別に溶媒抽出され、あるいは鉄、アルミニウムが分離されそれぞれの金属硫酸塩水溶液２として除去され、第１の塩化リチウム水溶液を得ることができる。
<Extraction process>
The neutralized acid solution is then subjected to solvent extraction in STEP 3. In the solvent extraction, manganese, cobalt, and nickel, excluding lithium, among the valuable metals are each extracted with a solvent, or iron and aluminum are separated and removed as aqueous metal sulfate solutions 2, thereby obtaining a first aqueous lithium chloride solution.
前記抽出工程で使用される有機溶媒として、例えばリン酸水素ビス（２－エチルヘキシル）、２－エチルヘキシル（２－エチルヘキシル）ホスホネート、及びビス（２，４，４－トリメチルペンチル）ホスフィン酸が挙げられる。前記有機溶媒は炭化水素、例えばケロシンで希釈されていてよい。 Examples of organic solvents used in the extraction process include bis(2-ethylhexyl) hydrogen phosphate, 2-ethylhexyl (2-ethylhexyl) phosphonate, and bis(2,4,4-trimethylpentyl)phosphinic acid. The organic solvent may be diluted with a hydrocarbon, such as kerosene.
前記鉄含有有機相、アルミニウム含有有機相、マンガン含有有機相、コバルト含有有機相、及びニッケル含有有機相のそれぞれに対し硫酸による逆抽出が実施され、金属硫酸塩（硫酸鉄、硫酸アルミニウム、硫酸マンガン、硫酸コバルト、及び硫酸ニッケル）水溶液２が回収される。 The iron-containing organic phase, aluminum-containing organic phase, manganese-containing organic phase, cobalt-containing organic phase, and nickel-containing organic phase are each subjected to back-extraction with sulfuric acid, and an aqueous solution 2 of metal sulfates (iron sulfate, aluminum sulfate, manganese sulfate, cobalt sulfate, and nickel sulfate) is recovered.
本発明の別の実施形態では、前記リチウム含有物１は、塩湖、海水、及び汽水からなる群から選ばれる少なくとも１つ由来の鹹水、より好ましくは塩湖由来の鹹水であってよい。カルシウム、マグネシウム、及びホウ素の少なくとも１つが前記鹹水から除去されてよい。前記除去は、例えば特許第６１２２９４４号公報に示された方法で実施される。すなわち前記鹹水にアルカリ金属水酸化物及びその水溶液の少なくとも１つを混合し、マグネシウムを水酸化マグネシウムとして生成できる。この時、前記アルカリ金属水酸化物が混合された塩水のｐＨを８．５～１０．５に維持させ、ホウ素（例えば、ホウ素イオン）を水酸化マグネシウムに吸着させてマグネシウムとホウ素を共沈させることができる。ホウ素が吸着して沈殿した水酸化マグネシウムと塩水を分離させるため、ろ過等の固液分離によりマグネシウムとホウ素が同時に回収され、ろ液が得られる。前記ろ液にアルカリ金属水酸化物又はアルカリ金属炭酸塩（例えば、ＮａＯＨまたは炭酸塩を単独または混合して）を混合し、前記ろ液のｐＨを１２以上に維持させてカルシウムを沈殿させることができる。前記ろ液と混合される前記アルカリ金属水酸化物又はアルカリ金属炭酸塩の種類に応じて水酸化カルシウム又は炭酸カルシウムが沈殿し、カルシウムが前記鹹水から除去され、第１の塩化リチウム水溶液を得ることができる。
前記アルカリ金属水酸化物のアルカリ金属はリチウム、ナトリウム、カリウム、ルビジウム、セシウム、及びフランシウムの少なくとも１つを含む。前記アルカリ金属は、好ましくはリチウム、ナトリウム、及びカリウムの少なくとも１つを含み、より好ましくはリチウムである。
In another embodiment of the present invention, the lithium-containing material 1 may be brine derived from at least one selected from the group consisting of a salt lake, seawater, and brackish water, more preferably brine derived from a salt lake. At least one of calcium, magnesium, and boron may be removed from the brine. The removal may be performed, for example, by the method disclosed in Japanese Patent No. 6122944. Specifically, magnesium can be produced as magnesium hydroxide by mixing the brine with at least one of an alkali metal hydroxide and an aqueous solution thereof. The pH of the brine containing the alkali metal hydroxide is maintained at 8.5 to 10.5, and boron (e.g., boron ions) can be adsorbed onto the magnesium hydroxide, resulting in the co-precipitation of magnesium and boron. To separate the magnesium hydroxide precipitated by the adsorption of boron from the brine, magnesium and boron are simultaneously recovered by solid-liquid separation, such as filtration, to obtain a filtrate. The filtrate can be mixed with an alkali metal hydroxide or alkali metal carbonate (e.g., NaOH or carbonate, alone or in combination) to maintain the pH of the filtrate at 12 or higher to precipitate calcium. Depending on the type of alkali metal hydroxide or alkali metal carbonate mixed with the filtrate, calcium hydroxide or calcium carbonate precipitates, removing calcium from the brine and providing a first lithium chloride aqueous solution.
The alkali metal of the alkali metal hydroxide includes at least one of lithium, sodium, potassium, rubidium, cesium, and francium. The alkali metal preferably includes at least one of lithium, sodium, and potassium, and more preferably lithium.
＜第１の膜電解工程＞
前記２つの実施形態は、次に、ＳＴＥＰ４でイオン交換膜を用いて、前記第１の塩化リチウム水溶液を膜電解する第１の膜電解工程を含む。ＳＴＥＰ４の前記第１の膜電解工程は、例えば、図２に示す膜電解槽１１を用いて行うことができる。
<First membrane electrolysis step>
The two embodiments then include a first membrane electrolysis step of performing membrane electrolysis on the first lithium chloride aqueous solution using an ion exchange membrane in STEP 4. The first membrane electrolysis step in STEP 4 can be performed using, for example, a membrane electrolysis cell 11 shown in FIG.
膜電解槽１１は、一方の内側面に陽極板１２を備え、陽極板１２と対向する内側面に陰極板１３を備え、陽極板１２は電源の陽極１４に接続され、陰極板１３は電源の陰極１５に接続されている。また、膜電解槽１１は、イオン交換膜１６により、陽極板１２を備える陽極室１７と、陰極板１３を備える陰極室１８とに区画されている。 The membrane electrolysis cell 11 has an anode plate 12 on one of its inner surfaces and a cathode plate 13 on the inner surface opposite the anode plate 12. The anode plate 12 is connected to the anode 14 of a power supply, and the cathode plate 13 is connected to the cathode 15 of the power supply. The membrane electrolysis cell 11 is also partitioned by an ion exchange membrane 16 into an anode chamber 17 containing the anode plate 12 and a cathode chamber 18 containing the cathode plate 13.
膜電解槽１１では、陽極室１７に前記第１の塩化リチウム水溶液を供給して膜電解を行うと、塩化物イオンが陽極板１２上で塩素ガス（Ｃｌ２）を生成する一方、リチウムイオンはイオン交換膜１６を介して陰極室１８に移動する。 In the membrane electrolysis cell 11, when the first lithium chloride aqueous solution is supplied to the anode chamber 17 and membrane electrolysis is performed, chloride ions generate chlorine gas (Cl 2 ) on the anode plate 12, while lithium ions move to the cathode chamber 18 through the ion exchange membrane 16.
陰極室１８では水（Ｈ２Ｏ）が水酸化物イオン（ＯＨ－）と水素イオン（Ｈ＋）とに電離し、水素イオンが陰極板１３上で水素ガス（Ｈ２）を生成する一方、水酸化物イオンがリチウムと化合して水酸化リチウム水溶液３を生成する。 In the cathode chamber 18, water (H 2 O) is ionized into hydroxide ions (OH − ) and hydrogen ions (H + ), and the hydrogen ions generate hydrogen gas (H 2 ) on the cathode plate 13, while the hydroxide ions combine with lithium to generate a lithium hydroxide aqueous solution 3.
前記第１の膜電解工程で用いる電力は、好ましくは再生可能エネルギーによって得られた電力を含み、より好ましくは太陽光発電、風力発電、水力発明、及びバイオマス発電からなる群から選択される少なくとも１つによって得られた電力を含む。 The electricity used in the first membrane electrolysis step preferably includes electricity obtained from renewable energy, and more preferably includes electricity obtained from at least one source selected from the group consisting of solar power generation, wind power generation, hydropower generation, and biomass power generation.
前記実施形態では、前記第１の膜電解工程で生成した水素ガス（Ｈ２）と塩素ガス（Ｃｌ２）とを反応させることにより、塩酸４を得ることができ、塩酸４はＳＴＥＰ１で前記固体１の溶解に用いることができる。 In the embodiment, hydrochloric acid 4 can be obtained by reacting hydrogen gas (H 2 ) generated in the first membrane electrolysis process with chlorine gas (Cl 2 ), and the hydrochloric acid 4 can be used to dissolve the solid 1 in STEP 1.
＜リチウムの回収＞
前記第１の膜電解工程により得られた水酸化リチウム水溶液３中のリチウムを、ＳＴＥＰ５で晶析により水酸化リチウム一水和物（ＬｉＯＨ・Ｈ２Ｏ）として回収でき、ＳＴＥＰ６で炭酸化することにより、炭酸リチウム（Ｌｉ２ＣＯ３）としても回収できる。前記炭酸化は、水酸化リチウム水溶液３を、炭酸ガス（ＣＯ２）と反応させることにより行うことができる。前記炭酸化工程で得られるスラリーをろ過等により固液分離して得られる塩化リチウム水溶液は、後述するＳＴＥＰ７で濃縮されてよい。
<Lithium recovery>
Lithium in the lithium hydroxide aqueous solution 3 obtained in the first membrane electrolysis step can be recovered as lithium hydroxide monohydrate (LiOH.H 2 O) by crystallization in STEP 5, and can also be recovered as lithium carbonate (Li 2 CO 3 ) by carbonation in STEP 6. The carbonation can be carried out by reacting the lithium hydroxide aqueous solution 3 with carbon dioxide gas (CO 2 ). The lithium chloride aqueous solution obtained by solid-liquid separation of the slurry obtained in the carbonation step by filtration or the like may be concentrated in STEP 7 described below.
水酸化リチウム水溶液３をＳＴＥＰ３で溶媒抽出に用いる場合、水酸化リチウム水溶液３は抽出溶媒に添加される。ＳＴＥＰ３で溶媒抽出に用いられる抽出溶媒は陽イオン交換抽出剤であるので、継続して使用すると液性が酸性側に偏り抽出率が低下するが、水酸化リチウム水溶液３を添加することにより、抽出率の低下を抑制できる。 When lithium hydroxide aqueous solution 3 is used for solvent extraction in STEP 3, lithium hydroxide aqueous solution 3 is added to the extraction solvent. The extraction solvent used for solvent extraction in STEP 3 is a cation exchange extractant, so continued use will cause the liquid to become more acidic and the extraction rate to decrease. However, adding lithium hydroxide aqueous solution 3 can prevent this decrease in extraction rate.
また、水酸化リチウム水溶液３をＳＴＥＰ３で溶媒抽出に用いる場合、水酸化リチウム水溶液３は、各別に行われるマンガン、コバルト、ニッケルの溶媒抽出の少なくとも１つの溶媒抽出に用いてよい。 Furthermore, when lithium hydroxide aqueous solution 3 is used for solvent extraction in STEP 3, lithium hydroxide aqueous solution 3 may be used for at least one of the solvent extractions of manganese, cobalt, and nickel, which are performed separately.
また、前記第１の膜電解工程では、前記第１の塩化リチウム水溶液が膜電解される結果、当該第１の塩化リチウム水溶液より希薄な第２の塩化リチウム水溶液が生成する。そこで、前記実施形態では、前記第２の塩化リチウム水溶液の一部と前記第１の塩化リチウム水溶液を混合してＳＴＥＰ７で濃縮し、第３の塩化リチウム水溶液を得てよい。ＳＴＥＰ７での濃縮は、例えば逆浸透膜（ＲＯ膜）及び蒸発濃縮からなる群から選ばれる少なくとも１つを用いて行うことができる。 Furthermore, in the first membrane electrolysis step, the first lithium chloride aqueous solution is subjected to membrane electrolysis, resulting in the production of a second lithium chloride aqueous solution that is more dilute than the first lithium chloride aqueous solution. Therefore, in the above embodiment, a portion of the second lithium chloride aqueous solution may be mixed with the first lithium chloride aqueous solution and concentrated in STEP 7 to obtain a third lithium chloride aqueous solution. The concentration in STEP 7 can be performed using, for example, at least one method selected from the group consisting of a reverse osmosis membrane (RO membrane) and evaporation concentration.
＜第２の膜電解工程＞
前記第１の電解工程では、塩素酸塩が陰極室１８から逆泳動してくる水酸化物イオンによって生成され、蓄積される。前記蓄積された塩素酸塩は、アルカリ金属水酸化物水溶液の膜電解におけるアルカリ金属水酸化物の品質悪化、及び設備の劣化原因となる。そこで、前記実施形態は、前記第１の膜電解工程で発生する塩素酸塩を含有する塩化リチウム水溶液を膜電解する第２の膜電解工程を含む。
<Second membrane electrolysis step>
In the first electrolysis step, chlorate is generated and accumulated by hydroxide ions that reversely migrate from the cathode chamber 18. The accumulated chlorate causes deterioration of the quality of the alkali metal hydroxide in the membrane electrolysis of the alkali metal hydroxide aqueous solution and deterioration of the equipment. Therefore, the embodiment includes a second membrane electrolysis step in which membrane electrolysis is performed on a lithium chloride aqueous solution containing chlorate generated in the first membrane electrolysis step.
前記陽極室１７中の、塩素酸塩を含む塩化リチウム水溶液の一部を第２の膜電解工程に付す。前記第２の膜電解工程は、例えば、図３に示す膜電解槽２１を用いて行うことができる。 A portion of the lithium chloride aqueous solution containing chlorate in the anode chamber 17 is subjected to a second membrane electrolysis process. The second membrane electrolysis process can be carried out, for example, using the membrane electrolysis cell 21 shown in Figure 3.
膜電解槽２１は、一方の内側面に陽極板２２を備え、陽極板２２と対向する内側面に陰極板２３を備え、陽極板２２は電源の陽極２４に接続され、陰極板２３は電源の陰極２５に接続されている。また、膜電解槽２１は、イオン交換膜２６により、陽極板２２を備える陽極室２７と、陰極板２３を備える陰極室２８とに区画されている。 The membrane electrolysis cell 21 has an anode plate 22 on one of its inner surfaces and a cathode plate 23 on the inner surface opposite the anode plate 22. The anode plate 22 is connected to the anode 24 of a power supply, and the cathode plate 23 is connected to the cathode 25 of the power supply. The membrane electrolysis cell 21 is also partitioned by an ion exchange membrane 26 into an anode chamber 27 containing the anode plate 22 and a cathode chamber 28 containing the cathode plate 23.
膜電解槽２１では、陽極室２７に希硫酸を供給して膜電解を行うと、水（Ｈ２Ｏ）が水酸化物イオン（ＯＨ－）と水素イオン（Ｈ＋）とに電離し、陽極板２２上で酸素ガス（Ｏ２）を生成する一方、水素イオン（Ｈ＋）はイオン交換膜２６を介して陰極室２８に移動する、下記式（１）で示される反応が起きる。
３Ｈ２Ｏ→１．５Ｏ２＋６Ｈ＋＋６ｅ－ （１）
In the membrane electrolysis cell 21, when dilute sulfuric acid is supplied to the anode chamber 27 and membrane electrolysis is performed, water (H 2 O) is ionized into hydroxide ions (OH − ) and hydrogen ions (H + ), generating oxygen gas (O 2 ) on the anode plate 22, while the hydrogen ions (H + ) move to the cathode chamber 28 through the ion exchange membrane 26, as shown in the reaction represented by the following formula (1).
3H 2 O → 1.5O 2 +6H + +6e - (1)
陰極室２８では、前記塩素酸塩を含む塩化リチウム水溶液が供給されて、前記塩素酸塩と水が反応して、塩化リチウムと水酸化物イオン（ＯＨ－）が生成する、下記式（２）で示される反応が起きる。
ＬｉＣｌＯ３＋３Ｈ２Ｏ＋６ｅ－→ＬｉＣｌ＋６ＯＨ－ （２）
陽極室２７から移動してきた水素イオン（Ｈ＋）は、生成した水酸化物イオン（ＯＨ－）と中和される。
In the cathode chamber 28, an aqueous lithium chloride solution containing the chlorate is supplied, and the chlorate reacts with water to produce lithium chloride and hydroxide ions (OH − ), as shown in the following formula (2):
LiClO 3 +3H 2 O+6e - →LiCl+6OH - (2)
The hydrogen ions (H + ) that have moved from the anode chamber 27 are neutralized with the hydroxide ions (OH − ) that have been produced.
前記第２の膜電解工程で用いる電力は、好ましくは再生可能エネルギーによって得られた電力を含み、より好ましくは太陽光発電、風力発電、水力発明、及びバイオマス発電からなる群から選択される少なくとも１つによって得られた電力を含む。 The electricity used in the second membrane electrolysis step preferably includes electricity obtained from renewable energy, and more preferably includes electricity obtained from at least one source selected from the group consisting of solar power generation, wind power generation, hydropower generation, and biomass power generation.
前記第２の膜電解工程で塩素酸塩が分解され、その濃度が低減された、塩素酸塩を含む塩化リチウム水溶液は、前記第１の膜電解工程で使用される電解槽１１の陽極室１７に戻される。 The chlorate-containing lithium chloride aqueous solution, in which the chlorate has been decomposed and its concentration reduced in the second membrane electrolysis process, is returned to the anode chamber 17 of the electrolytic cell 11 used in the first membrane electrolysis process.
１・・・リチウムを含む物質、 ２・・・金属硫酸塩水溶液、
３・・・水酸化リチウム水溶液、 ３Ａ・・・水酸化リチウム一水和物、 ４・・・塩酸
４Ａ・・・アルカリ金属水酸化水溶液、 ５・・・塩酸、 ６・・・炭酸リチウム、
１１、２１…電解槽、１２、２２…陽極板、 １３、２３…陰極板、
１４、２４…陽極、 １５、２５…陰極、 １６、２６…イオン交換膜、
１７、２７…陽極室、 １８、２８…陰極室。
1... Substance containing lithium, 2... Metal sulfate aqueous solution,
3...Lithium hydroxide aqueous solution, 3A...Lithium hydroxide monohydrate, 4...Hydrogen acid
4A... alkali metal hydroxide aqueous solution, 5... hydrochloric acid, 6... lithium carbonate,
11, 21... Electrolytic cell, 12, 22... Anode plate, 13, 23... Cathode plate,
14, 24... anode, 15, 25... cathode, 16, 26... ion exchange membrane,
17, 27... Anode chamber, 18, 28... Cathode chamber.
Claims (7)
第１の塩化リチウム水溶液を膜電解し、水酸化リチウム水溶液、塩酸、及び当該第１の塩化リチウム水溶液よりも希薄な、塩素酸塩を含有する第２の塩化リチウム水溶液を得る第１の膜電解工程、及び、
当該塩素酸塩を含有する第２の塩化リチウム水溶液を膜電解する第２の膜電解工程を含む、リチウム膜電解後の淡塩水の処理方法。 A method for treating fresh saltwater after lithium membrane electrolysis, comprising:
a first membrane electrolysis step of subjecting a first lithium chloride aqueous solution to membrane electrolysis to obtain a second lithium chloride aqueous solution containing a lithium hydroxide aqueous solution, hydrochloric acid, and a chlorate salt that is more dilute than the first lithium chloride aqueous solution; and
a second membrane electrolysis step of performing membrane electrolysis on a second lithium chloride aqueous solution containing the chlorate salt;
リチウムを含む固体を塩酸で溶解して酸溶解液を得る酸溶解工程、
当該酸溶解液に水酸化リチウムを添加する中和工程、及び、
当該中和工程で得られた酸溶解液から、リチウムを除く少なくとも１種の金属を溶媒抽出により分離し、当該溶媒抽出の残液として前記第１の塩化リチウム水溶液を得る溶媒抽出工程を更に含み、
前記水酸化リチウム水溶液の一部を、当該中和工程、及び当該溶媒抽出工程からなる群から選択される少なくとも１つで使用される水酸化リチウムとして用い、前記第１の膜電解工程で発生する塩酸を当該酸溶解工程で用いる、リチウム膜電解後の淡塩水の処理方法。 The method for treating fresh saltwater after lithium membrane electrolysis according to claim 1,
an acid dissolution step of dissolving the lithium-containing solid in hydrochloric acid to obtain an acid solution;
a neutralization step of adding lithium hydroxide to the acid solution; and
a solvent extraction step of separating at least one metal other than lithium from the acid solution obtained in the neutralization step by solvent extraction, and obtaining the first lithium chloride aqueous solution as a residue of the solvent extraction,
a part of the lithium hydroxide aqueous solution is used as lithium hydroxide to be used in at least one step selected from the group consisting of the neutralization step and the solvent extraction step, and hydrochloric acid generated in the first membrane electrolysis step is used in the acid dissolution step.
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| JP2016539252A (en) | 2013-10-23 | 2016-12-15 | ネマスカ リチウム インコーポレーテッド | Method and system for preparing lithium hydroxide |
| JP2021017627A (en) | 2019-07-22 | 2021-02-15 | 株式会社ササクラ | Lithium recovery method |
| WO2021166479A1 (en) | 2020-02-17 | 2021-08-26 | 住友金属鉱山株式会社 | Lithium hydroxide production method |
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| JP2021017627A (en) | 2019-07-22 | 2021-02-15 | 株式会社ササクラ | Lithium recovery method |
| WO2021166479A1 (en) | 2020-02-17 | 2021-08-26 | 住友金属鉱山株式会社 | Lithium hydroxide production method |
| WO2023027190A1 (en) | 2021-08-27 | 2023-03-02 | 国立大学法人弘前大学 | Lithium recovery device and lithium recovery method |
| WO2023048196A1 (en) | 2021-09-22 | 2023-03-30 | 株式会社アサカ理研 | Treatment method for chlorine gas |
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