JP7342466B2 - Lithium evaluation method - Google Patents

Description

The present invention relates to a lithium evaluation method.

Lithium, one of the rare metals, is used in the ceramic industry, such as as an additive for ceramics, heat-resistant glass, and optical glass, as well as in various batteries for small electronic devices, automobiles, and private power generation, as well as as a treatment for depression. Lithium is widely used in medical and pharmaceutical applications, heat- and pressure-resistant greases, fluxes for continuous steel casting, and polymerization catalysts for synthetic rubber. It is used. Lithium carbonate is used as a cathode material and electrolyte in lithium-ion batteries (LIBs), and demand has been rapidly increasing in recent years. Lithium hydroxide is also used primarily as a positive electrode material for lithium-ion batteries, and is also used in automotive grease. In addition, lithium bromide is used as a refrigerant absorber in large-scale air conditioning absorption refrigerators for buildings and factories, and lithium chloride is used as an air conditioning dehumidifier and welding flux. Metallic lithium is a raw material for foil for primary battery anode materials and butyllithium for synthetic rubber catalysts.In addition to its compound and metal forms, lithium ore is also used directly as a melting point depressant in the ceramic industry. It is being

As described above, lithium has a wide range of industrial uses and is in high demand, so research has been conducted to date on methods that can accurately evaluate the lithium content of intermediates and final products obtained in manufacturing processes in various fields.・Development has been carried out.

As a method for evaluating lithium content, ion chromatography is proposed in Patent Document 1 and Patent Document 2. Further, the ICP method is proposed in Patent Document 3.

Japanese Patent Application Publication No. 11-287793 Japanese Patent Application Publication No. 2010-25791 Japanese Patent Application Publication No. 2010-78381

These evaluation methods were relative analysis techniques that required an instrumental analyzer and standard substances and standard solutions that served as measuring sticks for analysis. For this reason, for example, there is a problem that the accuracy of lithium analysis decreases due to the instrumental analyzer, such as a relative error of 1 to 3% depending on the stability of the plasma in an inductively coupled plasma (ICP) emission spectrometer. Ta. Furthermore, these relative analysis methods have a problem in that the accuracy of lithium analysis decreases due to the effects of ionization interference and optical interference from other coexisting elements.

On the other hand, there is an absolute analysis method, which is an evaluation method that measures the absolute amount of the evaluation element. Since this method does not require comparing the sample with a standard substance or the like using an instrumental analyzer, it is possible to prevent the above-mentioned decrease in analysis accuracy caused by the instrumental analyzer. Furthermore, since this method measures the absolute amount of the evaluation element, it is possible to prevent a decrease in analysis accuracy due to the influence of other coexisting elements. For this reason, the absolute analysis method has the advantage of being able to perform highly accurate analysis compared to the relative analysis method.

However, due to the nature of alkali metals such as lithium, it is extremely difficult to apply gravimetric methods or titration methods that allow for highly accurate analysis.

The present invention has been made in view of the above-mentioned problems, and by using the gravimetric method, which is an absolute analysis method, the lithium contained in a sample is free from the effects of various problems peculiar to relative analysis methods using instrumental analyzers. First, one purpose is to provide a technique that allows accurate and highly accurate evaluation even when coexisting elements are included.

As a result of research, the present inventor separated lithium from coexisting elements such as nickel, cobalt, manganese, and aluminum contained in a sample by making full use of ion exchange operations, precipitation operations, and electrolytic operations, and further, in the process of It was discovered that by decomposing and removing generated by-products such as ammonium sulfate, the weight of lithium can ultimately be measured in the form of lithium compounds such as lithium sulfate.

In the first aspect of the present invention, lithium contained in a sample is separated in the form of a lithium compound, the lithium compound is weighed to determine the lithium content, and then the lithium compound is subjected to ICP Provided is a method for evaluating lithium, characterized in that qualitative analysis is performed using one or more of ICP-MS and ICP-MS methods . In the second aspect of the present invention, the lithium contained in the sample is separated in the form of a lithium compound, the lithium compound is weighed to determine the lithium content, and then the lithium compound is Provided is a lithium evaluation method characterized by morphological analysis using X-ray diffraction.

According to this aspect, lithium contained in a sample can be evaluated accurately and with high precision even when coexisting elements are included without being affected by various problems peculiar to relative analysis techniques using instrumental analyzers.

A third aspect of the present invention is a lithium evaluation method for determining the lithium content by separating lithium contained in a sample in the form of a lithium compound and weighing the lithium compound, the method comprising: After dissolving the sample with acid to obtain a solution, there is a sample dissolution step of controlling the acid concentration of the solution, and the solution with controlled acid concentration is passed through an ion exchange resin column to obtain an effluent. After that, an ion exchange step for controlling the acid concentration of the effluent, and an electrolytic step for obtaining an electrolytic residual solution by adding alkali and electrolyzing the effluent with controlled acid concentration after treating the effluent with white smoke, and the electrolytic residual solution. A lithium compound generation step in which a lithium compound is obtained by decomposing and removing by-products by heating and igniting the container together, after collecting a part of the electrolytic residual solution into a container; A method for evaluating lithium is provided, comprising an analysis step of weighing the compound in the container and quantifying lithium.

In this way, the lithium contained in the sample can be evaluated accurately and with high precision even when coexisting elements are included without being affected by the problems peculiar to the relative analysis method using an instrumental analyzer.

A fourth aspect of the present invention is that in the lithium evaluation method of the third aspect, between the ion exchange step and the electrolysis step, the pH of the effluent with controlled acid concentration is adjusted with acid and/or alkali. , a lithium evaluation method comprising a precipitation step of producing a metal hydroxide precipitate by boiling and filtering the precipitate to obtain a filtrate, and treating the filtrate with white smoke in the electrolysis step. I will provide a.

In this way, even if the sample contains aluminum or the like, the lithium contained in the sample can be evaluated accurately and with high precision.

A fifth aspect of the present invention provides a lithium evaluation method according to any one of the first to fourth aspects , characterized in that the lithium compound is lithium sulfate.

From the viewpoint of hygroscopicity and complexity of the production process, lithium sulfate is suitable as the lithium compound to be weighed.

A sixth aspect of the present invention provides a lithium evaluation method according to the third aspect, characterized in that the acid is hydrochloric acid and the ion exchange resin column is an anion exchange resin column. .

In this way, coexisting elements such as cobalt, manganese, iron, and zinc can be adsorbed onto the column in the form of a chloro complex, and can be separated from lithium, which is the element to be analyzed.

A seventh aspect of the present invention provides the lithium evaluation method according to the third aspect, wherein the container is a quartz stoppered Erlenmeyer flask.

In this way, it is possible to prevent droplets from scattering outside the container in the lithium compound production step. Then, in the lithium analysis step, it is possible to prevent the lithium compound from absorbing moisture in the atmosphere and becoming a hydrate.

An eighth aspect of the present invention provides a lithium evaluation method according to the third or fourth aspect, characterized in that the alkali in the lithium evaluation method is aqueous ammonia.

By using ammonia water, it is possible to prevent new contamination of elements other than the coexisting elements derived from the sample as impurities.

A ninth aspect of the present invention provides a lithium evaluation method according to any one of the first to eighth aspects, wherein the sample contains one or more of nickel, cobalt, manganese, and aluminum. provide.

Even when the above-mentioned coexisting elements are included, the lithium contained in the sample can be evaluated accurately and with high precision.

A tenth aspect of the present invention provides the lithium evaluation method according to the third aspect, wherein the by-product is ammonium sulfate.

In this way, it is possible to prevent new contamination of elements other than the coexisting elements originating from the sample as impurities.

In an eleventh aspect of the present invention, in the lithium evaluation method of the third aspect, the lithium loss in the ion exchange step and the electrolysis step is measured by atomic absorption method, flameless atomic absorption method, ICP method, ICP-MS. The present invention provides a method for evaluating lithium, characterized in that lithium is determined using one or more of the following methods:

In this way, the lithium loss in the ion exchange process and the electrolytic process can be reflected, so that the lithium contained in the sample can be evaluated accurately and with high precision.

In a twelfth aspect of the present invention, in the lithium evaluation method of the fourth aspect, the lithium loss in the ion exchange step, the precipitation step, and the electrolysis step is measured by atomic absorption method, flameless atomic absorption method, ICP method. , ICP-MS method, and ion chromatography method.

In this way, the lithium loss in the ion exchange step, the precipitation step, and the electrolysis step can be reflected, so that the lithium contained in the sample can be evaluated accurately and with high precision.

A thirteenth aspect of the present invention is the lithium evaluation method according to any one of the third, fourth, sixth to eighth, tenth, and eleventh aspects, after calculating the lithium content, the lithium compound is , ICP method, and ICP-MS method are used for qualitative analysis.

In this way, it can be confirmed that no coexisting elements remain in the lithium compound obtained in the lithium analysis step, so that the lithium contained in the sample can be evaluated accurately and with high precision.

A fourteenth aspect of the present invention is the lithium evaluation method according to any one of the third, fourth, sixth to eighth, and tenth to twelfth aspects, in which the lithium compound is morphized using an X-ray diffraction method. Provided is a lithium evaluation method characterized by analyzing lithium.

In this way, it can be confirmed that the obtained lithium compound is not hydrated due to moisture absorption or carbonated due to carbon dioxide in the atmosphere. Therefore, the lithium contained in the sample can be evaluated accurately and with high precision.

With the present invention, by using the gravimetric method, which is an absolute analysis method, lithium contained in a sample is not affected by the problems peculiar to relative analysis methods using instrumental analyzers, even when coexisting elements are included. , can be evaluated accurately and with high precision.

FIG. 1 is a flow diagram for explaining a lithium evaluation method according to one embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail. Note that the present embodiment described below does not unduly limit the content of the present invention described in the claims, and changes can be made without departing from the gist of the present invention. Furthermore, not all of the configurations described in this embodiment are essential as a solution to the present invention.

The lithium evaluation method according to one embodiment of the present invention is based on a gravimetric method in which the weight of lithium contained in a sample is directly weighed, and lithium is evaluated by an absolute analysis method.

Here, representative examples of lithium evaluation methods that have been used in the past include atomic absorption method and flame method, as well as ICP method, ion chromatography method, and the like.

For example, in the ion chromatography method, a sample is thermally decomposed with a mixed acid of hydrochloric acid, nitric acid, and water, and then hydrogen peroxide is added and boiled. (Patent Document 1), a sample is heated with nitric acid and hydrogen peroxide using an ion chromatograph equipped with a separation column packed with a cation exchange resin and an anion exchange suppressor. There is a method (Patent Document 2) in which a measurement solution obtained by decomposition is measured using at least one of potassium, ammonium, and an amine compound as an internal standard element. In addition, in the ICP method, when measuring a sample solution obtained by thermally decomposing a sample with nitric acid and hydrogen peroxide using an inductively coupled plasma (ICP) emission spectrometer, the plasma excitation temperature is set to 4900 K or higher. In addition, if the target elements include at least two of lithium, nickel, cobalt, manganese, and aluminum, use gallium as the internal standard element for lithium, aluminum, and manganese. , nickel, and cobalt, there is a method using copper (Patent Document 3).

However, in atomic absorption spectrometry, flame photometry, and ICP methods, the analytical accuracy is usually within a relative error of 1 to 3%, mainly due to flame flame or plasma stability, and even higher precision analysis is required. If this is done, appropriate measures must be taken to prevent ionization interference and optical interference from other coexisting elements. In addition, in the ion chromatography method, sample weighing operation, thermal decomposition operation, constant volume operation that adjusts the volume of the sample solution to a fixed amount, dilution operation that dilutes the sample solution and the standard solution for creating the calibration curve to a fixed ratio. There has been a problem in that the accuracy of lithium analysis is significantly reduced by continuously performing a series of pretreatment operations.

By the way, the above-mentioned internal standard method involves adding an element that exhibits a physical behavior similar to the target element to be analyzed in both the standard solution of the calibration curve method and the measurement solution in which the sample is pretreated. This method corrects the measured value of the target element by adding a certain amount as an internal standard element and monitoring the effect on the internal standard element (assuming that the sample does not originally contain the internal standard element). . It is originally a method for correcting physical interference that the element to be analyzed receives during measurement, such as a decrease in the introduction efficiency of the measurement solution due to the influence of matrix components.

However, in any of the above evaluation methods, the internal standard element may be added and mixed immediately after the sample is weighed, not from the measurement stage using the analyzer, and then a pretreatment operation may be performed. However, like the isotope dilution method (a method in which a fixed amount of concentrated stable isotope of the target element is added to the sample and the measured value is corrected based on its behavior), which has been adopted as a method for determining the standard value of the standard material, It is highly unlikely that the element to be analyzed and the internal standard element exhibit exactly the same chemical and physical properties. Strict caution is required, as there is a risk that this will appear as a significant analysis error and have negative effects.

All of the above evaluation methods are relative analysis methods that require an instrumental analyzer and standard substances and standard solutions that serve as measuring sticks for analysis.The isotope dilution method is the only relative analysis method. , it is a method that can determine the standard value of a reference material. On the other hand, since ancient times, methods for determining the standard value of a reference material have been the gravimetric method, in which the weight of the target element itself is weighed directly, or the analytical value is calculated from the added volume of a reagent that quantitatively reacts with the target element. Absolute analysis methods, which are based on stoichiometry and do not require an instrumental analyzer, have been adopted, such as the volumetric method to determine the . However, even today, it is said that it is extremely difficult to apply gravimetric methods or titration methods, which allow for highly accurate analysis, due to the nature of alkali metals such as lithium.

For example, in the gravimetric method, lithium is analyzed and evaluated by measuring the weight of lithium contained in a sample, but for this purpose it is necessary to separate lithium from other coexisting elements. Furthermore, for highly accurate analysis, it is necessary to ensure that the separated lithium does not contain any elements other than lithium (also referred to as "coexisting elements" in this application) as impurities, and that the separated coexisting elements do not contain lithium. It becomes necessary. The presence of these impurities prevents accurate measurement of lithium weight and significantly reduces the accuracy of lithium analysis.

Coexisting elements include elements having various properties, such as nickel, cobalt, manganese, and aluminum. For this reason, it has been difficult to separate lithium and coexisting elements so that impurities and the like are not included. Further, when an alkali metal element is contained as an impurity, it is particularly difficult to separate it from lithium, which causes a problem of significantly reducing the accuracy of lithium analysis. Therefore, for highly accurate analysis, there is a problem in that reagents containing alkali metal elements such as sodium hydroxide cannot be used when separating lithium.

In order to solve the above-mentioned problems, the present inventor has made full use of ion exchange operation, precipitation operation, and electrolysis operation as means to separate lithium from the coexisting elements such as nickel, cobalt, manganese, and aluminum. , focused on the ability to separate lithium. In addition, by gently decomposing and removing by-products such as ammonium sulfate generated during the lithium compound generation process and lithium analysis process, lithium compounds such as lithium sulfate are finally produced. It has been discovered that lithium can be evaluated accurately and with high precision in the form of the following, and the present invention has been completed.

In addition, in this application, "analysis" usually refers to "quantitative analysis," and when "qualitative analysis" is performed, that fact will be stated each time. Note that "quantitative analysis" is an analysis method for correctly determining the content of the target component in a sample, and "qualitative analysis" is an analysis method for determining the content of the target component in a sample. This is an analysis method for obtaining qualitative information such as whether the target component is present or how much of the component to be analyzed is contained (also called semi-quantitative). Generally, "qualitative analysis" is used to clarify the unknown components and their approximate content, and then "quantitative analysis" is performed on the components to be analyzed. If it is known, "quantitative analysis" can be performed immediately.

An overview of the lithium evaluation method according to one embodiment of the present invention will be described below.

[1. Overview of lithium evaluation method]
First, an overview of the lithium evaluation method will be explained using drawings. FIG. 1 is a flow diagram for explaining a lithium evaluation method according to one embodiment of the present invention. As shown in FIG. 1, the lithium evaluation method according to one aspect of the present invention includes a sample dissolution step S1, an ion exchange step S2, a precipitation step S3, an electrolysis step S4, a lithium compound generation step S5, and a lithium analysis step S6. Ru.

[1-1. Sample dissolution step S1]
In the sample dissolution step S1, the sample is thermally decomposed with hydrochloric acid, and then hydrochloric acid is added to control the acid concentration for post-processes including the ion exchange step S2 described later. In the ion exchange step S2, which will be described later, it is preferable to dissolve the sample in hydrochloric acid in order to separate lithium and coexisting elements by adsorbing the chloro complex onto an anion exchange resin column. Although the chloro complex produced differs depending on the acid concentration, the acid concentration is preferably 8M or more and 12M or less, and more preferably 9M or more and 11M or less. By controlling the acid concentration within this range, the adsorption capacity of cobalt and manganese chlorocomplexes to the resin column can be optimized, so it is possible to separate these coexisting elements and lithium in the ion exchange step S2. can. If the acid concentration is less than 8M, the cobalt chloro complex will not be sufficiently adsorbed onto the resin column, making it impossible to separate lithium and coexisting elements.

[1-2. Ion exchange step S2]
In the ion exchange step S2, an anion exchange resin column is used to adsorb coexisting elements such as cobalt, manganese, iron, and zinc in the form of chloro complexes (complex anions), and lithium, which is the element to be analyzed, is removed from the column. Let it flow. This allows separation of lithium and coexisting elements. By the way, when using a cation exchange resin column, lithium will be adsorbed onto the column, but with simple liquids such as hydrochloric acid, coexisting elements such as nickel, cobalt, manganese, and aluminum will also be absorbed into the column. It is difficult to completely separate lithium because it remains adsorbed to the surface. However, even in an anion exchange resin column, nickel, aluminum, and the like other than lithium do not generate chloro complexes (complex anions), so they flow out of the column together with lithium.

[1-3. Precipitation step S3]
In the precipitation step S3, coexisting elements such as aluminum that could not be separated from lithium in the ion exchange step S2 are separated in the form of metal hydroxide. As the alkali for controlling the precipitation pH, aqueous ammonia is preferable. By using ammonia water, alkali metal elements such as sodium and potassium are prevented from being mixed in as impurities, and lithium can be evaluated accurately and with high precision in the lithium analysis step S6 described later. Furthermore, by using aluminum hydroxide or the like as the coexisting element such as aluminum, lithium and the coexisting element can be separated. Furthermore, by using ammonium sulfate as a byproduct generated in the electrolysis step S4 described later, ammonium sulfate can be removed as gaseous ammonia, gaseous sulfur dioxide, nitrogen gas, and water vapor in the lithium compound generation step S5 described later. . Therefore, in the lithium compound generation step S5, it is possible to prevent the by-products described below from remaining as solids, so that in the lithium analysis step S6, lithium can be evaluated accurately and with high precision.

Alkali other than aqueous ammonia, such as an aqueous sodium hydroxide solution, cannot be used as an alkali for controlling the precipitation pH because sodium and potassium, which are the same alkali metal elements as lithium, are mixed in as impurities. Therefore, in the precipitation step S3 as well, nickel and the like that do not precipitate as metal hydroxides remain in the filtrate together with lithium by generating an ammonium water and ammine complex. Note that if the sample does not contain aluminum or the like, this precipitation step S3 can be omitted.

[1-4. Electrolysis process S4]
In the electrolysis step S4, coexisting elements such as nickel, which could not be separated from lithium in the ion exchange step S2 and the precipitation step S3, are separated by being deposited in the form of metal on the platinum cathode. After this electrolytic step S4, lithium can be separated from all coexisting elements. In the electrolysis step S4, as described later, aqueous ammonia is added to the effluent obtained in the ion exchange step S2 to make it alkaline and perform constant current electrolysis. The reason for using aqueous ammonia and its effect are the same as those described in the overview of the precipitation step S3, and therefore will be omitted. In the electrolytic step S4, sulfuric acid is used to pre-treat the sample, and since the electrolytic solution is ammoniacal, ammonium sulfate remains as a by-product along with lithium in the electrolytic residual solution.

[1-5. Lithium compound generation step S5]
In the lithium compound generation step S5, ammonium sulfate, which is a by-product, is decomposed and removed by various operations such as heating concentration, evaporation to dryness, and ignition, and only lithium compounds are generated. As mentioned above, ammonium sulfate can be removed in this step as gaseous ammonia, gaseous sulfur dioxide, nitrogen gas, and water vapor. Therefore, it is possible to prevent the by-product from remaining as a solid, so that lithium can be evaluated accurately and with high precision in the lithium analysis step S6, which will be described later. However, in each of these operations, especially during evaporation to dryness or ignition, when the amount of ammonium sulfate by-product increases, the droplets are likely to scatter, and if the droplets escape from the container, the lithium contained in the droplets will be lost. This becomes a major error factor. By performing this step using a quartz stoppered Erlenmeyer flask, it is possible to prevent droplets from scattering outside the container during evaporation to dryness or ignition, and to prevent the loss of lithium contained in the droplets. It can be prevented. Therefore, lithium can be evaluated accurately and with high precision.

[1-6. Lithium analysis step S6]
In the lithium analysis step S6, the generated lithium compound is allowed to cool and then weighed using an electronic balance. However, some lithium compounds have strong hygroscopic properties, so they tend to absorb moisture from the atmosphere and change from anhydrous salts to hydrates. Here, by performing the decomposition and removal of by-products in the lithium compound generation step S5 using a quartz stoppered Erlenmeyer flask, the lithium analysis step can be performed in a state where it is isolated from the atmosphere. Therefore, weight changes due to hygroscopicity can be prevented, and lithium can be evaluated accurately and with high precision. In addition, after obtaining the weight of the lithium compound, the lithium compound is dissolved in water, and the aqueous solution is used for ICP qualitative analysis and ICP-MS qualitative analysis to confirm that no coexisting elements remain in the lithium compound. It can be confirmed. Thereby, the lithium contained in the sample can be evaluated accurately and with high precision.

In addition, as described later, lithium lost in the ion exchange step S2, precipitation step S3, and electrolysis step S4 can be removed by one of the following methods: atomic absorption method, flameless atomic absorption method, ICP method, ICP-MS method, and ion chromatography method. It is possible to analyze using the above. Then, the lithium content can be calculated by reflecting the lithium loss in each step on the measurement result of the lithium analysis step S6. Therefore, lithium can be evaluated accurately and with high precision.

As described above, the present invention has been made based on the above-mentioned findings obtained as research results, and has the above-mentioned effects.

[2. Lithium evaluation method]
<One embodiment of the present invention>
Hereinafter, a lithium evaluation method according to an embodiment of the present invention will be described.

In the present embodiment, a sample refers to a sample containing at least one of nickel, cobalt, manganese, and aluminum, and an example of this is a case where lithium of the sample is evaluated.

The lithium evaluation method of this embodiment includes a sample dissolution step S1, an ion exchange step S2, a precipitation step S3, an electrolysis step S4, a lithium compound generation step S5, and a lithium analysis step S6. The details of each step will be explained below.

[2-1. Sample dissolution step S1]
In the sample dissolution step S1, first, approximately 0.5 to 2 g of the sample to be analyzed is weighed using an electronic balance, and then water and hydrochloric acid are added to dissolve the sample to obtain a solution. For heating and cooling in the beaker, including the post-process, a watch glass is used as a lid if necessary.

By the way, when performing the gravimetric method, during the analysis process, new elements other than coexisting elements derived from the sample are introduced as impurities, which not only increases unnecessary separation operations but also makes separation difficult and analysis itself impossible. There is a fear. Therefore, when dissolving the sample, it is preferable to treat it with a simple liquid such as an inorganic acid, such as sodium carbonate or potassium disulfate, so as not to have a major adverse effect on the subsequent steps including the ion exchange step S2. It is preferable to avoid treatment by alkaline melting, such as by using

In addition, in the next step, ion exchange step S2, in order to adsorb and separate as many types of coexisting elements contained in the sample as possible, it is better to use hydrochloric acid rather than nitric or sulfuric acid for the solution solution. It is preferable that The acid concentration of hydrochloric acid can vary depending on the type of coexisting elements that you want to separate, but for example, for cobalt and manganese, 10 moles of hydrochloric acid (hereinafter also simply referred to as "M"), for iron, 8 M hydrochloric acid, and for zinc. If available, it is preferable to use 2M hydrochloric acid.

[2-2. Ion exchange step S2]
In the ion exchange step S2, as mentioned above, an anion exchange resin column is used, which is an ion exchange resin into which amino groups have been introduced as functional groups, and is capable of exchanging anions such as chlorine ions and sulfate ions. do. The anion exchange resins used to fill the column include the Dowex (registered trademark) series manufactured by The Dow Chemical Company and the Amberlite (registered trademark) series manufactured by Organo Co., Ltd. Generally widely used strong basic or weak basic ones can be used. For example, if it is a strong basic one, type I DOWEX-1x8 (100 -200 mesh).

As the anion exchange resin column, for example, one compliant with JIS-M-8129 (method for quantifying cobalt in ores) can be used. A glass column tube with a cock (inner diameter: approx. 25 mm, length of chromatograph section: approx. 350 mm) is loosely stuffed with absorbent cotton (glass cotton or Teflon cotton may be used) loosened with water to a thickness of 5 to 10 mm, and then soaked in water. Anion exchange resin (strongly basic, Cl ^- type) swollen with water is poured into the slurry. After the resin has settled, absorbent cotton loosened with water is loosely packed on top of it to a thickness of 5 to 10 mm. Furthermore, the flow rate of the effluent is controlled to about 3 to 5 mL per minute (SV=1 to 2) by adjusting the way the absorbent cotton is packed and the opening degree of the cock.

Here, BV (Bed Volume) is a unit that indicates how many times the volume of liquid is passed through the resin, whereas SV (Space Velocity) is the unit that indicates how many times the volume of liquid is passed per hour. , is a unit that indicates how many times the resin volume the liquid is passed through.

The anion exchange resin is regenerated into the OH - form using aqueous ammonia (7+100) as shown in formula (I), and then regenerated into the OH ^- form using hydrochloric acid (1+100) as shown in formula (II). ^- It is preferable to use it after replacing it with a mold. Here, in the case of hydrochloric acid, "1+100" means 1 volume of hydrochloric acid + 100 parts of water. Furthermore, in the following formulas (I) and (II), A represents the base of the ion exchange resin.
A-N・Cl + NH ₄ OH → A-N・OH + NH ₄ Cl (I)
A-N・OH + HCl → A-N・Cl + H ₂ O (II)

By performing the above operation, it is possible to prevent a decrease in adsorption capacity that may occur due to deterioration of the anion exchange resin due to continuous use. The regeneration operation is carried out in the following order: hydrochloric acid (1+100) → water → aqueous ammonia (7+100) → water → hydrochloric acid (1+100) in an amount corresponding to the amount of anion exchange resin used, that is, in the above example, 360 mL each. Pass through the column.

Before passing the solution obtained in the sample dissolution step S1 through the column, prepared hydrochloric acid having the same acid concentration as the solution is passed through the column to fill the entire column with the prepared hydrochloric acid. Additionally, after passing the lysate through the column, at least twice the resin volume of prepared hydrochloric acid is used to completely drain the lithium from the column. The obtained effluent is once heated and concentrated and evaporated to dryness for the post-process, and then the generated salts are heated and dissolved again with water and hydrochloric acid to control the hydrochloric acid concentration to a predetermined concentration. If the hydrochloric acid concentration is too low, the salts produced by evaporation to dryness will remain undissolved, which will impede accurate measurement of lithium weight and significantly reduce the accuracy of lithium analysis. The concentration of hydrochloric acid is not particularly limited as long as it can dissolve salts, but the higher the concentration of hydrochloric acid, the greater the amount of ammonia water used in the precipitation process, and the longer it takes to remove hydrochloric acid in the pretreatment for the electrolysis process. Increases cost and time required for lithium analysis. From the viewpoints of analysis accuracy, cost, and time, the hydrochloric acid concentration is preferably 1M or more and 2M or less.

The coexisting elements adsorbed on the column can be eluted from the column by using hydrochloric acid prepared appropriately for each element, or by using, for example, an eluent prepared by dissolving 1 g of ascorbic acid in 1 L of hydrochloric acid (1+9). In addition, the coexisting elements contained in the obtained recovered liquid, along with the lithium lost (remaining in the column) during the ion exchange operation, can be analyzed using atomic absorption spectrometry, flameless atomic absorption spectrometry, ICP method, ICP-MS method, and ion chromatography method. It is possible to analyze using one or more of the following.

Note that the next step after the ion exchange step S2 is a precipitation step S3 if the sample contains aluminum or the like, and if the sample does not contain aluminum or the like, the precipitation step S3 is omitted and the process proceeds to the electrolysis step S4.

[2-3. Precipitation step S3]
In the precipitation step S3, if the sample contains aluminum or the like, water is added to the acid concentration-controlled effluent obtained in the ion exchange step S2 to adjust the liquid volume, and then hydrochloric acid (1+1) and/or aqueous ammonia is added. The precipitation pH is controlled to a predetermined value, and coexisting elements are precipitated and separated in the form of metal hydroxides. Precipitation pH is preferably 5 or more and 10 or less, more preferably 6 or more and 9 or less. By controlling the precipitation pH within these ranges, aluminum can be precipitated as aluminum hydroxide, and lithium and coexisting elements can be separated. As mentioned above, ammonia water is used as the alkali for controlling the precipitation pH, since it does not introduce new impurities other than the coexisting elements derived from the sample. In order to reduce the amount of ammonium sulfate produced in the subsequent lithium compound production step S5, it is particularly preferable to reduce the amount of ammonia water added as much as possible by carefully controlling the precipitation pH. An ammonium salt such as ammonium chloride can also be added as a pH buffer, but care must be taken not to increase the amount added too much in this case as well. Furthermore, from the viewpoint of separation from coexisting elements, it is particularly preferable to age the precipitate by heating and boiling the effluent at a low temperature before separating and collecting the precipitate of the metal hydroxide. Boiling increases the rate of precipitate formation, suppresses adsorption of other components by the precipitate, and coarsens the precipitate particles, thereby promoting separation of lithium and coexisting elements. Furthermore, the efficiency of washing the precipitate can be improved. Precipitation separation can be performed by known means such as suction filtration in addition to normal natural filtration, and examples of filter paper used for filtration include ordinary quantitative filter paper (Type 5 A specified in JIS P 3801, Type 5 B, type 5 C), cellulose acetate filter paper, hydrophilic PTFE filter paper, etc. may be used. In addition, the separated precipitate may be washed 5 to 6 times with pure water or diluted ammonia water, for example.

Coexisting elements precipitated in the form of metal hydroxides are dissolved, for example, in warm hydrochloric acid (1+1), and together with lithium lost in the precipitation operation (remaining in the precipitation), atomic absorption method, flameless atomic absorption method, ICP method, It is possible to analyze using one or more of ICP-MS method and ion chromatography method.

[2-4. Electrolysis process S4]
In the electrolysis step S4, sulfuric acid (1+1) is added to the acid concentration controlled effluent obtained in the ion exchange step S2 or the filtrate obtained in the precipitation step S3 and concentrated by heating to generate white smoke. Adjust the liquid volume with sulfuric acid (1+1) and water, add ammonia water to make it alkaline, and perform constant current electrolysis. For electrolysis, commercially available electrolytic devices can be used, for example, electrolytic analyzer AES-2D manufactured by Yanaco Technical Science Co., Ltd., electrolytic analyzer ANA-2-2 manufactured by Tokyo Kohden Co., Ltd., etc. I can do it. As the electrode, a spiral platinum anode and a cylindrical platinum cathode described in JIS-H-1101 (copper metal analysis method) can be used. After boiling in nitric acid (1+1), water, Wash with ethanol and dry at 105°C for 30 minutes or more before use. Further, in addition to an electrolytic beaker (a 200 mL tall beaker may be used), two semicircular watch glasses are used, and the electrolytic conditions are set to a current of 0.3 to 0.7 A and a time of 10 to 30 hours. Further, by the heating and concentration described above, hydrochloric acid in the effluent or filtrate can be evaporated and removed. This can prevent chlorine from remaining as an impurity, so lithium can be evaluated accurately and with high precision in the lithium analysis step S6. Note that sulfuric acid is a non-volatile acid and its boiling point is 337°C, which is higher than the boiling point of hydrochloric acid, 110°C, so the generation of sulfuric acid white smoke can confirm that no hydrochloric acid is present in the effluent or filtrate. In this application, the above operations of adding sulfuric acid, heating concentration, and generating white smoke are also referred to as white smoke treatment.

The coexisting elements deposited on the platinum cathode are analyzed by electrolytic gravimetry, for example, by subtracting the dry weight of the platinum cathode before electrolytic operation (before precipitation of coexisting elements) from the dry weight of platinum cathode after electrolytic operation (after precipitation of coexisting elements). However, in addition to that, only the coexisting elements can be thermally decomposed from the platinum cathode after electrolytic operation (after precipitation of coexisting elements) with nitric acid (1+1), and the lithium lost during electrolytic operation (remaining on the platinum cathode side) can be removed. In addition, analysis can be performed using one or more of the following methods: atomic absorption method, flameless atomic absorption method, ICP method, ICP-MS method, and ion chromatography method.

[2-5. Lithium compound generation step S5]
In the lithium compound production step S5, the electrolysis residual solution obtained in the electrolysis step S4 is heated and concentrated, and once the volume is fixed to a predetermined volume, an appropriate amount is taken out and transferred to a container for ignition. By performing this operation, as mentioned earlier, you can reduce the coexisting amount of ammonium sulfate and make it difficult for droplets to scatter outside the container during evaporation to dryness or ignition, so do not perform fixed-volume or preparative operations. This is particularly preferable. Moreover, a quartz stoppered Erlenmeyer flask is used as the above-mentioned container for ignition. This is especially preferable to using a platinum plate, quartz plate, magnetic plate, etc., since the container opening is narrow, making it difficult for droplets to scatter outside the container during evaporation to dryness or intense heat. . Note that ammonium sulfate gradually begins to decompose at about 120°C, and at 357°C, it releases ammonia and melts. During evaporation to dryness, the heating temperature is adjusted in the range of 100 to 320° C. to prevent bumping of the concentrated liquid. When igniting heat, it is better to raise the temperature as gently as possible, as it is easy to cause droplets to scatter if the process is suddenly raised to a high temperature. Using an electric muffle furnace, etc., the temperature increase pattern is from room temperature to 350℃ (10 minutes). It is particularly preferable to perform ignition under the following conditions: →400°C (20 minutes) →450°C (10 minutes) and the heating time to each set temperature is 10 minutes. Upon ignition, ammonium sulfate is removed from the ignition vessel as gaseous ammonia, gaseous sulfur dioxide, nitrogen gas, and water vapor.

[2-6. Lithium analysis step S6]
In the lithium analysis step S6, the lithium compound obtained in the lithium compound generation step S5 is left to cool in a desiccator, and then weighed together with the ignition container using an electronic balance. After ignition is completed, the ignition container is immediately stored in a desiccator to prevent the lithium compound from absorbing moisture in the atmosphere and becoming a hydrate, and allowed to cool to room temperature. When a quartz stoppered Erlenmeyer flask is used as the ignition container, it is particularly preferable to using a platinum plate, a quartz plate, a magnetic plate, etc., because it can be sealed and shut off from the atmosphere. In addition, in terms of weight, types of lithium compounds include lithium sulfate, lithium chloride, lithium carbonate, lithium bromide, etc., but lithium chloride is the most hygroscopic, while lithium carbonate and lithium bromide are produced. Since this requires a complicated process, lithium sulfate is particularly preferred.

The weight of the obtained lithium compound is converted into a lithium equivalent weight, and by reflecting the sample amount in the sample dissolution step S1, the fixed capacity and fractional amount in the lithium compound generation step S5, and the lithium loss in each step, lithium The content can be calculated. In addition, after obtaining the weight of the lithium compound, the lithium compound is dissolved in water, and the aqueous solution is used for ICP qualitative analysis and ICP-MS qualitative analysis to confirm that no coexisting elements remain in the lithium compound. It can be confirmed. Furthermore, in the above qualitative analysis, if it is confirmed that a coexisting element remains in an amount that may affect the quantitative value of lithium, we will continue to use atomic absorption spectrometry, flameless atomic absorption spectrometry, ICP method, ICP-MS. Lithium can be analyzed using one or more of the following methods: method, ion chromatography, and subtracted from the lithium quantitative value. Thereby, the lithium contained in the sample can be evaluated accurately and with high precision. In addition, a part of the obtained lithium compound may be collected, or a sample for confirming the compound form may be prepared separately from the sample for parallel analysis, which will be described later, and the sample may be analyzed using X-ray diffraction (XRD). It is possible to analyze the morphology. Thereby, it can be confirmed that the obtained lithium compound is not hydrated due to moisture absorption or carbonated due to carbon dioxide in the atmosphere. Furthermore, since the effects of hydration and carbonation can be eliminated, the lithium contained in the sample can be evaluated accurately and with high precision. That is, for example, in the present invention, the form of the lithium compound finally obtained after all the analysis steps is particularly preferably lithium sulfate, as described above. However, if the obtained lithium compound contains other forms such as hydrates and carbonates, if the total weight of the lithium compound is converted to lithium equivalent weight as lithium sulfate, then the lithium compound may coexist with the lithium compound. This will affect the quantitative value of lithium in the same way as when there is residual element. Therefore, the obtained lithium compound is morphologically analyzed using X-ray diffraction (XRD) method, and the result is reflected (in this example, it is proved that the lithium compound is a single compound of lithium sulfate). By doing so, the reliability of the lithium quantitative value can be further improved.

<Details of analysis method according to this embodiment>
Details of the analysis method according to this embodiment will be described below.

According to the steps shown in FIG. 1, lithium contained in samples X and Y (both metal composite oxides) was evaluated. Table 1 shows the compositions of matrix elements in samples X and Y, which were separately analyzed using an inductively coupled plasma (ICP) emission spectrometer. Sample X contains nickel, cobalt, and aluminum as main components, and sample Y contains nickel, cobalt, and manganese as main components, which coexist with lithium, which is an element to be analyzed.

In addition, the lithium loss in each process, the qualitative analysis of the lithium compound (lithium sulfate) after weighing, and each comparative example (analysis of lithium by conventional method using acid decomposition solution), all of these analyzes are performed using ICP. The law was used. Each sample was introduced into an inductively coupled plasma (ICP) emission spectrometer (ICP-OES "Agilent 730-ES" manufactured by Agilent Technologies), and lithium and coexisting elements were measured under the measurement conditions shown in Table 2. , and a qualitative analysis was conducted. The measurement wavelength for each element was 610.365 nm for lithium, 222.295 nm for nickel, 235.341 nm for cobalt, 396.152 nm for aluminum, and 279.827 nm for manganese, and 371 nm for yttrium, which was selected as an internal standard element. .030 nm. In addition, regarding the liquid properties of the measurement solution, hydrochloric acid was 1.2M, the yttrium concentration was 10 mg/L, and the calibration curve concentrations were 0, 1, 5, 10, and 50 mg/L.

As described below, the present invention will be explained based on more detailed examples, but the present invention is not limited to these examples.

<Example 1>
In this example, lithium contained in sample X was processed and evaluated in three samples in parallel according to the steps shown in FIG.

First, 2 g of sample After cooling the solution, 30 mL of hydrochloric acid was added to control the acid concentration to 10M hydrochloric acid, and the flow rate of the effluent was about 3 to 5 mL per minute (SV = 1 to 2) to an anion exchange resin column. I passed it as expected. The anion exchange resin column used was one compliant with JIS-M-8129 (method for quantifying cobalt in ores) as described above, and the resin used was DOWEX-1x8 (100-200 mesh). The effluent was received in a 500 mL beaker and washed by passing 360 mL of prepared hydrochloric acid (10 M hydrochloric acid) in portions through the column to completely drain the lithium from the column.

Coexisting elements such as cobalt and manganese adsorbed on the column were eluted from the column by using hydrochloric acid (1+9) as an eluent and passing the column through the column in portions of 360 mL. Thereafter, the obtained recovered liquid was transferred to a 500 mL volumetric flask, 14 mL of hydrochloric acid and 50 mL of an internal standard solution of yttrium solution (100 mg/L) were added, and the volume was adjusted to 500 mL with water. The coexisting elements contained in this recovered liquid, together with the lithium lost in the ion exchange operation (remaining in the column), were analyzed by the ICP method while performing a dilution operation as appropriate.

The effluent was concentrated by heating, transferred to a 200 mL tall beaker, and continued to be heated to evaporate to dryness. Then, 20 mL of pure water and 2 mL of 12M hydrochloric acid were added to dissolve the produced salts while adjusting the acid concentration of the effluent. was again controlled to about 1M hydrochloric acid. Furthermore, pure water was added to the effluent to adjust the liquid volume to approximately 100 mL, and then the pH was adjusted to around 7 with hydrochloric acid (1+1) and ammonia water containing 28% ammonia by mass to form metal hydroxide precipitates. I let it happen. The generated precipitate was heated to boiling at 120° C. and held for 15 minutes or more to perform heat aging. Thereafter, it was separated by gravity filtration using filter paper (5A, 125 mm), and washed 5 to 6 times with warm ammonia water (1+100). Note that the filtrate was collected in a 200 mL tall beaker.

Coexisting elements such as aluminum contained in the precipitate were dissolved in 50 mL of warm hydrochloric acid (1+1), and the resulting recovered liquid was transferred to a 500 mL volumetric flask, and 50 mL of yttrium solution (100 mg/L), which was an internal standard solution, was added. The volume was then adjusted to 500 mL with water. The coexisting elements contained in this recovered liquid, along with the lithium lost in the precipitation operation (remaining in the precipitate), were analyzed by the ICP method while appropriately performing a dilution operation.

To the obtained filtrate, 10 mL of sulfuric acid (1+1) was added, heated and concentrated to generate white smoke, then allowed to cool, 10 mL of sulfuric acid (1+1) was added again, and the liquid volume was reduced to 100 mL with pure water. It was adjusted. Furthermore, 50 mL of ammonia water containing 28% ammonia by mass was added to make it alkaline. Electrolysis was carried out using the platinum electrodes and beakers described in (Copper metal analysis method) at a current of 0.3 A (current density: approximately 2 mA/dm ² ) and a time of 15 hours. .

Coexisting elements such as nickel deposited on the surface of the platinum cathode are thermally decomposed using 100 mL of nitric acid (1+1), and the obtained recovered liquid is transferred to a 500 mL volumetric flask, and 50 mL of hydrochloric acid and an yttrium solution as an internal standard solution are added. (100 mg/L) was added thereto, and the volume was made up to 500 mL with water. The coexisting elements contained in this recovered solution, together with the lithium lost in the electrolytic operation (remaining on the platinum cathode side), were analyzed by the ICP method while appropriately performing a dilution operation.

The residual electrolytic solution after removing the platinum electrode was heated and concentrated, transferred to a 100 mL volumetric flask, and the volume was made up to 100 mL with pure water. From the electrolyzed residual solution, take 50 mL with a 50 mL whole pipette, transfer it to a weighed 200 mL quartz stoppered Erlenmeyer flask manufactured by Cosmos Bead Co., Ltd., and heat it at 100 to 320 °C using a hot plate. Heat concentration and evaporation to dryness were performed while adjusting. The obtained salt was placed in an electric muffle furnace together with the flask, and the temperature was increased from room temperature to 350°C (10 minutes) to 400°C (20 minutes) to 450°C (10 minutes), and the heating time to each set temperature was 10 minutes. The mixture was ignited using a heating pattern of 1 minute.

The flask was taken out from the electric muffle furnace, cooled to the extent that it would not cause burns when touched, and then immediately stoppered and stored in a desiccator, and the obtained lithium sulfate was allowed to cool to room temperature. Thereafter, the flask was taken out from the desiccator, the weight (flask weight after operation) was measured using an electronic balance, and the weight of lithium sulfate was determined by subtracting the original flask weight (flask weight before operation). In addition, since 50 mL was taken from 100 mL of the electrolytic residual solution, the weight of the obtained lithium sulfate was doubled to make it the weight equivalent to the original sample amount, and the coefficient was 0.1263 (the weight of lithium in 1 mol of lithium sulfate Li ₂ SO ₄ ). The weight in terms of lithium was determined by multiplying the mass by 13.882/molar mass of lithium sulfate (109.945).

After obtaining the weight of lithium sulfate, lithium sulfate was dissolved in water, the resulting aqueous solution was transferred to a 100 mL volumetric flask, and the volume was adjusted to 100 mL with water. ICP qualitative analysis was performed using this aqueous solution to confirm the presence or absence of residual coexisting elements in lithium sulfate.

After calculating the total weight of lithium by adding the lithium loss in each step of the ion exchange step, precipitation step, and electrolysis step to the obtained lithium equivalent weight and subtracting the blank sample portion described later, the formula (III) is calculated. The final quantitative value of lithium was calculated as shown in .
Lithium quantitative value [%] = (Total lithium weight [g] / Sample amount [g]) x 100 (III)

In this example, apart from samples 1 to 3, lithium-added samples 4 to 5 were prepared as samples for evaluating the lithium recovery rate. Specifically, after weighing the sample in the sample dissolution step, 0.2661 g of lithium carbonate was added so that the amount of lithium was 0.05 g, and thereafter, the same procedure as for samples 1 to 3 was performed according to the steps shown in FIG. processed. Note that the lithium recovery rate (also referred to as "recovery rate") was calculated as shown in formula (IV).
Lithium recovery rate [%]
= {(added sample lithium weight [g] - sample average lithium weight [g])
/Additional amount of lithium [g]}×100 (IV)

In addition, in this example, blank samples 6 to 7 were prepared for a blank test in addition to samples 1 to 3. Specifically, in the sample dissolution step, the same treatment as Samples 1 to 3 was performed according to the steps shown in FIG. 1, except that the samples were not weighed.

Furthermore, in this example, apart from Samples 1 to 3, a form confirmation sample 8 was prepared as a sample for confirming the compound form. Specifically, according to the steps shown in FIG. 1, the same treatments as samples 1 to 3 were performed, and the obtained lithium compounds were analyzed using an X-ray diffraction (XRD) analyzer ("X'PertPRO" manufactured by Spectris Co., Ltd.). The morphology was analyzed using In the X-ray diffraction analyzer, CuKα radiation is used as a radiation source for the sample collected in the sample holder, the measurement speed is 2°/min, the tube voltage is 45 kV, the tube current is 40 mA, and the measurement range is 2θ= Measurements were made at an angle of 10° to 80°. Then, the compound form was identified by comparing the standard diffraction pattern of the compound with the diffraction pattern of the sample using the PDF (Powder Diffraction File) database in the International Center for Diffraction Data (ICDD).

Table 3 shows the quantitative value of lithium, the lithium recovery rate, and the form of the lithium compound in this example.

<Example 2>
In Example 2, the sample to be analyzed was Sample Y, and the same operations as in Example 1 were performed, except that the precipitation step was omitted, and the quantitative value of lithium and the lithium recovery rate were calculated.

Table 3 shows the quantitative value of lithium, the lithium recovery rate, and the form of the lithium compound in Example 2.

<Comparative example 1>
In Comparative Example 1, the sample to be analyzed is Sample X, and after thermal decomposition in the sample dissolution step, the obtained acid decomposed solution was transferred to a 500 mL volumetric flask, and 30 mL of hydrochloric acid and 100 mg of yttrium solution as an internal standard solution were added. /L) was added thereto, and the volume was made up to 500 mL with pure water. Lithium and coexisting elements in this acid decomposed solution were analyzed by ICP method while performing dilution operation as appropriate.

Table 3 shows the quantitative value of lithium and the lithium recovery rate in Comparative Example 1.

<Comparative example 2>
In Comparative Example 2, the same operations as in Comparative Example 1 were performed except that Sample Y was used as the sample to be analyzed.

Table 3 shows the quantitative value of lithium and the lithium recovery rate in Comparative Example 2.

<Evaluation results>
As shown in Table 3, according to Examples 1 and 2, it was found that all three lithium quantitative values of Samples 1 to 3 were in agreement when calculated using three significant figures. It was also found that the lithium recovery rates of lithium-added samples 4 and 5 were all 99.9% or higher. Furthermore, in form confirmation sample 8, it was confirmed that the obtained lithium compound was composed only of lithium sulfate (Li ₂ SO ₄ ), and other forms of compounds such as hydrates and carbonates were not detected. There wasn't. This result shows that if the present invention is used, the lithium contained in the sample can be separated in the form of a lithium compound such as lithium sulfate, resulting in a very good recovery rate of lithium even if coexisting elements are included. It was confirmed that lithium can be collected and that lithium can be evaluated accurately and with high precision. After weighing the lithium sulfate, an ICP qualitative analysis of the lithium sulfate was performed to confirm the presence or absence of any remaining coexisting elements, but no coexisting elements were detected. Furthermore, we analyzed the content of coexisting elements along with the lithium loss in each process by ICP method, and the quantitative values of nickel, cobalt, aluminum, and manganese almost matched the composition of matrix elements shown in Table 1. Ta. This result shows that coexisting elements such as nickel, cobalt, aluminum, and manganese can be evaluated along with lithium if operated according to the present invention. Moreover, from this result, it was confirmed that if the present invention is used, it is possible to reflect the lithium loss in each process, and lithium can be evaluated accurately and with high precision.

On the other hand, according to Comparative Examples 1 and 2, the lithium quantitative values of Samples 1 to 3 did not match when calculated using three significant figures. The lithium recovery rates of lithium-added samples 4 and 5 were all less than 99.9%. As mentioned above, this is considered to be affected by various problems specific to the relative analysis method using an instrumental analyzer, such as plasma stability during ICP measurement. From the above, it was confirmed that the ICP method cannot perform evaluations as accurate and highly accurate as the gravimetric method, which is an absolute analysis method.

Although each embodiment and each example of the present invention has been described in detail as above, those skilled in the art will appreciate that many modifications can be made without substantially departing from the novelty and effects of the present invention. , it will be easy to understand. Therefore, all such modifications are included within the scope of the present invention.

For example, a term that appears at least once in the specification or drawings together with a different term with a broader or synonymous meaning may be replaced by that different term anywhere in the specification or drawings. Further, the configuration and operation of the lithium evaluation method are not limited to those described in each embodiment and each example of the present invention, and various modifications are possible.

S1 sample dissolution process, S2 ion exchange process, S3 precipitation process, S4 electrolysis process, S5 lithium compound generation process, S6 lithium analysis process

Claims (14)

After determining the lithium content by separating the lithium contained in the sample in the form of a lithium compound and weighing the lithium compound, the lithium compound is subjected to one of the ICP method and ICP-MS method. A lithium evaluation method characterized by qualitative analysis using the above . After determining the lithium content by separating the lithium contained in the sample in the form of a lithium compound and weighing the lithium compound, the lithium compound is subjected to morphological analysis using an X-ray diffraction method. A lithium evaluation method featuring: A lithium evaluation method for determining lithium content by separating lithium contained in a sample in the form of a lithium compound and weighing the lithium compound, the method comprising:
A sample dissolving step of dissolving the weighed sample with acid to obtain a solution, and then controlling the acid concentration of the solution;
An ion exchange step of flowing the solution with controlled acid concentration through an ion exchange resin column to obtain an effluent, and then controlling the acid concentration of the effluent;
An electrolytic step in which the acid concentration controlled effluent is treated with white smoke, and then an alkali is added and electrolyzed to obtain an electrolyzed residual solution;
A lithium compound generation step in which the volume of the electrolytic residual solution is determined, a part of the electrolytic residual solution is collected in a container, and the byproducts are decomposed and removed by heating and igniting the container together to obtain a lithium compound. and,
an analysis step of weighing the lithium compound together with the container and quantifying lithium;
A lithium evaluation method characterized by having the following. Between the ion exchange step and the electrolysis step, the pH of the effluent with controlled acid concentration is adjusted with acid and/or alkali and boiled to generate a metal hydroxide precipitate, and the precipitate is removed. It has a precipitation step to obtain a filtrate by filtration,
4. The lithium evaluation method according to claim 3 , wherein the filtrate is treated with white smoke in the electrolysis step. The lithium evaluation method according to claim 1, wherein the lithium compound is lithium sulfate. 4. The lithium evaluation method according to claim 3 , wherein the acid is hydrochloric acid and the ion exchange resin column is an anion exchange resin column. 4. The lithium evaluation method according to claim 3 , wherein the container is a quartz stoppered Erlenmeyer flask. 5. The lithium evaluation method according to claim 3 , wherein the alkali in the lithium evaluation method is aqueous ammonia. The lithium evaluation method according to any one of claims 1 to 8 , wherein the sample contains one or more of nickel, cobalt, manganese, and aluminum. 4. The lithium evaluation method according to claim 3 , wherein the by-product is ammonium sulfate. The lithium loss in the ion exchange step and the electrolysis step is determined using one or more of atomic absorption method, flameless atomic absorption method, ICP method, ICP-MS method, and ion chromatography method. The lithium evaluation method according to claim 3 . Determining the lithium loss in the ion exchange step, the precipitation step, and the electrolysis step using one or more of atomic absorption method, flameless atomic absorption method, ICP method, ICP-MS method, and ion chromatography method. The lithium evaluation method according to claim 4 , characterized by: After calculating the lithium content, the lithium compound is qualitatively analyzed using one or more of ICP method and ICP-MS method. The lithium evaluation method according to any one of the items. The lithium evaluation method according to any one of claims 3, 4, 6 to 8, and 10 to 12, characterized in that the lithium compound is subjected to morphological analysis using an X-ray diffraction method.

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