JP6173931B2 - Method for producing alkali metal iodide or alkaline earth metal iodide - Google Patents

Description

  The present invention relates to a method for producing an alkali metal iodide or an alkaline earth metal iodide.

  Alkali metal iodides or alkaline earth metal iodides are very useful compounds used for various reaction reagents or additives.

  Lithium iodide is used as an absorption liquid for absorption refrigerators, and as a promoter for acetic acid production. In addition, applications in the field of electronic materials such as lithium secondary batteries, dye-sensitized solar cells, and organic EL have been actively developed.

  As a method for producing solid lithium iodide, a method in which an aqueous lithium iodide solution is concentrated to the expected distillate amount, placed in an evaporating dish and cooled in a desiccator, and further dried in an inert gas to make an anhydrous product (Non-Patent Document 1), a method of heating and solidifying a filtrate of an aqueous lithium iodide solution at 85 ° C. in a vacuum furnace, a method of drying in a vacuum at 120 ° C. to make an anhydride (Non-Patent Document 2), atmospheric pressure A method of concentrating at 136 ° C. to make a trihydrate (Patent Document 1) is known.

  In addition, as a method for producing a commercial product, a method in which lithium iodide corresponding to almost trihydrate is flaked with a roller (Non-patent Document 1) is known. However, in order to obtain powdered lithium iodide, Absent.

  In addition, strontium iodide is being studied for use in the field of electronic materials.

  As a method for producing solid strontium iodide, a method of concentrating an aqueous strontium iodide solution and cooling, separating the precipitated crystals and drying in a desiccator to obtain hexahydrate, and further strontium iodide hexahydrate A method is known in which a product is mixed well with ammonium iodide, heated and melted under reduced pressure to dehydrate it into an anhydride (Non-patent Document 3).

US Pat. No. 3,402,995 (registered on September 24, 1968)

The Chemical Society of Japan, “New Experimental Chemistry Course”, Volume 8, p. 462-463, 1997, Maruzen Co., Ltd. The Chemical Society of Japan, “Fourth Edition, Experimental Chemistry Course”, Volume 16, p. 206, 1993, Maruzen Co., Ltd. The Chemical Society of Japan, “New Experimental Chemistry Course”, Volume 8, p. 618-619, 1997, Maruzen Co., Ltd.

  Alkali metal iodides or alkaline earth metal iodides are highly hygroscopic and often form hydrates. Because of the strong hygroscopicity of alkali metal iodides or alkaline earth metal iodides, for example, it takes a lot of time and heat to obtain anhydrate.

  Further, when lithium iodide is obtained by the method described in Patent Document 1 and Non-Patent Documents 1 or 2, or when strontium iodide is obtained by the method described in Non-Patent Document 3, it is obtained by cooling after concentration. Solid lithium iodide or strontium iodide will stick to the container. For this reason, it is difficult to take out in powder form. Therefore, the method described in the above document cannot be said to be a method for producing powdery lithium iodide or strontium iodide which can be industrially implemented.

  The present invention has been made in view of the above problems, and is capable of industrially producing a powdered alkali metal iodide or alkaline earth metal iodide, or an alkali metal iodide or alkaline earth metal iodide. It aims at providing the manufacturing method of.

  The method for producing an alkali metal iodide or alkaline earth metal iodide according to the present invention comprises producing an alkali metal iodide or alkaline earth metal iodide for producing a powdered alkali metal iodide or alkaline earth metal iodide. A method, wherein an alkali metal iodide or an alkaline earth metal iodide is dissolved or suspended in a solvent, an alkali metal iodide solution, an alkaline earth metal iodide solution, an alkali metal iodide suspension or It is characterized by including a removing and pulverizing step of pulverizing the alkali metal iodide or the alkaline earth metal iodide while removing the solvent from the alkaline earth metal iodide suspension.

  In the removing and pulverizing step, the solid matter adhered to the inner surface of the container containing the alkali metal iodide solution, alkaline earth metal iodide solution, alkali metal iodide suspension or alkaline earth metal iodide suspension is removed. It is preferable to remove the solvent and pulverize the alkali metal iodide or alkaline earth metal iodide while scraping with a rotary blade.

  It is preferable that the particle diameter of the powdered alkali metal iodide or alkaline earth metal iodide obtained by the removing and grinding step is 5 mm or less.

  The alkali metal iodide solution, alkaline earth metal iodide solution, alkali metal iodide suspension, or alkaline earth metal iodide suspension is an alkali metal compound or alkaline earth metal compound and iodide. It may be produced by a reaction step in which it is reacted.

  The solvent used in the reaction step may be water.

  The present invention has an effect that a powdery alkali metal iodide or alkaline earth metal iodide can be produced industrially.

  Hereinafter, embodiments of the present invention will be described in detail.

[Method for producing alkali metal iodide or alkaline earth metal iodide]
The method for producing an alkali metal iodide or alkaline earth metal iodide according to the present invention comprises producing an alkali metal iodide or alkaline earth metal iodide for producing a powdered alkali metal iodide or alkaline earth metal iodide. A method, wherein an alkali metal iodide or an alkaline earth metal iodide is dissolved or suspended in a solvent, an alkali metal iodide solution, an alkaline earth metal iodide solution, an alkali metal iodide suspension or A removal pulverization step of pulverizing the alkali metal iodide or the alkaline earth metal iodide while removing the solvent from the alkaline earth metal iodide suspension is included.

  According to the production method of the present invention, an alkali metal iodide solution, an alkaline earth metal iodide solution, an alkali iodide, in which an alkali metal iodide or an alkaline earth metal iodide is dissolved or suspended in a solvent. By removing the solvent from the metal suspension or alkaline earth metal iodide suspension while grinding the alkali metal iodide or alkaline earth metal iodide, powdered alkali metal iodide or alkaline earth iodide A similar metal can be suitably produced.

  In the method for producing an alkali metal iodide or alkaline earth metal iodide according to one embodiment, the alkali metal iodide solution or alkaline earth metal iodide solution includes an alkali metal compound or an alkaline earth metal compound and iodine. It is produced by a reaction step in which a compound is reacted in a solvent. The alkali metal iodide suspension or alkaline earth metal iodide suspension may be produced by concentrating the alkali metal iodide solution or alkaline earth metal iodide solution produced by the reaction step. Good.

  According to the above configuration, the alkali metal iodide solution, the alkaline earth metal iodide solution, the alkali metal iodide suspension, or the alkaline earth metal iodide suspension can be efficiently produced.

  The alkali metal iodide solution, alkaline earth metal iodide solution, alkali metal iodide suspension, or alkaline earth metal iodide suspension is not limited to those produced in the reaction step, Those prepared by the above method may be used, or commercially available products may be purchased.

  That is, the alkali metal iodide solution, alkaline earth metal iodide solution, alkali metal iodide suspension, or alkaline earth metal iodide suspension is an alkali metal iodide or alkaline earth iodide containing water. There is no limitation as long as the metal is dissolved or suspended in a solvent.

  Here, the alkali metal iodide containing water includes alkali metal iodide hydrate, and alkali metal iodide consolidated, suspended, or dissolved by absorbing moisture. Similarly, the alkaline earth metal iodide containing water includes an alkaline earth metal iodide hydrate and an alkaline earth metal iodide solidified, suspended, or dissolved by absorbing water. be able to. For example, commercially available alkali metal iodide hydrate or alkaline earth metal iodide hydrate may be purchased and used, and iodine that has solidified, suspended, or dissolved by absorbing moisture during storage. An alkali metal iodide or an alkaline earth metal iodide may be used.

[Reaction process]
In the method for producing an alkali metal iodide or alkaline earth metal iodide according to one embodiment, the alkali metal iodide or alkaline earth metal iodide solution comprises an alkali metal compound or an alkaline earth metal compound and iodide. It is produced by a reaction process in which reaction is carried out in a solvent. Preferably, in the reaction step, the following reaction is performed in an inert gas atmosphere such as nitrogen and argon.

(Wherein M is an alkali metal ion or alkaline earth metal ion, and X is an ion that forms a salt with the alkali metal ion or alkaline earth metal ion, and is a monovalent or divalent anion. And n is an integer of either 1 or 2. X is preferably a carbonate ion, bicarbonate ion, hydroxide ion, oxalate ion, or acetate ion.)
By the reaction of the formula (1), an alkali metal iodide or an alkaline earth metal iodide can be produced with high yield. Hereinafter, each compound in the reaction step will be described in more detail.

(Alkali metal compound or alkaline earth compound)
The alkali metal compound or alkaline earth metal compound is a compound represented by MX in the formula (1), and is not limited thereto, but examples thereof include lithium carbonate, lithium bicarbonate, lithium hydroxide, and lithium oxalate. , Lithium acetate, sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium oxalate, sodium acetate, potassium carbonate, potassium bicarbonate, potassium hydroxide, potassium oxalate, potassium acetate, rubidium carbonate, rubidium bicarbonate, rubidium hydroxide , Rubidium oxalate, rubidium acetate, cesium carbonate, cesium bicarbonate, cesium hydroxide, cesium oxalate, cesium acetate, beryllium carbonate, beryllium bicarbonate, beryllium hydroxide, beryllium oxalate, beryllium acetate, magnesium carbonate, magnesium bicarbonate Cium, magnesium hydroxide, magnesium oxalate, magnesium acetate, calcium carbonate, calcium bicarbonate, calcium hydroxide, calcium oxalate, calcium acetate, strontium carbonate, strontium bicarbonate, strontium hydroxide, strontium oxalate, strontium acetate, carbonic acid It can be barium, barium bicarbonate, barium hydroxide, barium oxalate, barium acetate, and the like. These alkali metal compounds and alkaline earth metal compounds may use anhydrides or hydrates.

In addition, it is more preferable to use an alkali metal carbonate, an alkaline earth metal carbonate, an alkali metal hydroxide, or an alkaline earth metal hydroxide as the alkali metal compound or alkaline earth metal compound. When an alkali metal carbonate or alkaline earth metal carbonate is used as the alkali metal compound or alkaline earth metal compound, H _n X as a by-product in the formula (1) becomes carbonic acid (H ₂ CO ₃ ), and water and Decomposes into carbon dioxide. Further, when an alkali metal hydroxide or an alkaline earth metal carbonate is used as the alkali metal compound or alkaline earth metal compound, H _n X as a by-product becomes water. Therefore, when an alkali metal carbonate, alkaline earth metal carbonate, alkali metal hydroxide, or alkaline earth metal hydroxide is used as the alkali metal compound or alkaline earth metal compound, by-products are removed in the subsequent dehydration step. The

(Iodide)
Iodide is used to produce an alkali metal iodide or an alkaline earth metal iodide by reacting with an alkali metal compound or an alkaline earth metal compound in the reaction step. Here, for example, hydroiodic acid can be used as the iodide. By reacting an alkali metal compound or alkaline earth metal compound with hydriodic acid, an alkali metal iodide or alkaline earth metal iodide can be suitably obtained. In addition, you may use the hydroiodic acid which removed the free iodine by refine | purifying.

(solvent)
In the reaction step, the reaction between the alkali metal compound or alkaline earth metal compound and hydriodic acid is performed in a solvent. Here, in one Embodiment, the said solvent used for the said reaction process is water.

  By performing the reaction between the alkali metal compound or alkaline earth metal compound and iodide in an aqueous solvent, an alkali metal iodide or alkaline earth metal iodide can be obtained efficiently. The water is more preferably water from which inorganic components have been removed. Examples of water from which inorganic components have been removed include ion exchange water, pure water, and ultrapure water. By preparing an aqueous solution of the alkali metal compound or alkaline earth metal compound, an alkali metal iodide aqueous solution or alkaline earth metal iodide aqueous solution that does not contain an inorganic component as an impurity, or an iodide that does not contain an inorganic component as an impurity. Alkali metal powders or alkaline earth metal iodide powders can be produced.

(Reaction conditions)
The alkali metal compound or alkaline earth metal compound is preferably in the range of 20 to 60% by weight in an aqueous solvent. The amount of hydroiodic acid used is preferably in the range of 0.5 to 1.5 molar equivalents relative to the alkali metal compound or alkaline earth metal iodide compound. Thereby, an alkali metal compound or an alkaline earth metal iodide compound can be efficiently dissolved in an aqueous solvent, and can be reacted efficiently with hydroiodic acid.

  Although a reaction process is not limited, it is good to carry out by dripping hydroiodic acid in inert gas atmosphere, such as nitrogen or argon, stirring the aqueous solution of an alkali metal compound or an alkaline-earth metal compound.

  The temperature in the reactor in the reaction step is preferably in the range of 0 to 100 ° C., and particularly preferably in the range of 10 to 50 ° C. for ease of production.

  In one embodiment, generation of free iodine may be controlled by using a stabilizer in the reaction step. The stabilizer is a reducing agent for free iodine, and examples thereof include phosphorus compounds such as hypophosphorous acid and phosphorous acid, sulfur compounds such as sulfurous acid, thiosulfuric acid and hydrogen sulfide, and hydrazine compounds such as hydrazine sulfate. It is done. Further, it is particularly preferable that the stabilizer is hypophosphorous acid. By using hypophosphorous acid, free iodine can be efficiently reduced without mixing metal ions.

  By using a stabilizer, free iodine in an alkali metal iodide aqueous solution or an alkaline earth metal iodide aqueous solution can be reduced to iodine ions. For this reason, coloring of the alkali metal iodide aqueous solution or the alkaline earth metal iodide aqueous solution due to free iodine can be reduced.

  The amount of the stabilizer used varies depending on the type of the stabilizer. For example, in the case of hypophosphorous acid, the amount is preferably 0.001 to 10% by weight, more preferably 0, based on hydroiodic acid used in the reaction. 0.005 to 1% by weight, more preferably 0.01 to 0.1% by weight. By using the amount of hypophosphorous acid within this range, the amount of hypophosphorous acid used can be reduced, and it is present in hydroiodic acid obtained by conventional production methods, including commercial products. Free iodine can be suitably reduced.

(Other processing)
In addition, after the reaction step is completed, it is preferable to adjust the pH of the obtained alkali metal iodide aqueous solution or alkaline earth metal iodide aqueous solution. From the viewpoint of the stability of the quality of the alkali metal iodide aqueous solution or alkaline earth metal iodide aqueous solution and the safety of the product, the pH of the alkali metal iodide aqueous solution or alkaline earth metal iodide aqueous solution is preferably 3 to 10, More preferably, it is adjusted in the range of 4 to 9, more preferably 5 to 8. As the pH adjuster, an alkali metal compound or an alkaline earth metal compound in the reaction step can be used, but it is particularly preferable to use an alkali metal hydroxide or an alkaline earth metal hydroxide.

  Moreover, it is preferable to remove free iodine from the alkali metal iodide aqueous solution or alkaline earth metal iodide aqueous solution obtained in the reaction step by using an adsorbent or an organic solvent immiscible with water.

  By removing free iodine from the aqueous alkali metal iodide solution or alkaline earth metal iodide solution, an aqueous solution of alkali metal iodide or alkaline earth metal iodide that is less colored by free iodine can be obtained. The content of free iodine in the alkali metal iodide aqueous solution or alkaline earth metal iodide aqueous solution is preferably less than 0.05% by weight, and more preferably less than 0.02% by weight. By setting the content of free iodine to less than 0.05% by weight, an alkali metal iodide aqueous solution or alkaline earth metal iodide aqueous solution that is not colored by free iodine can be obtained. As a result, white alkali metal iodide powder or alkaline earth metal iodide powder can be finally obtained.

  Examples of the adsorbent for removing free iodine include activated carbon, activated clay, cyclodextrin, zeolite, silica gel, and alumina. These adsorbents can be used alone or in admixture of two or more. The adsorbent may be removed by filtration after being put into an alkali metal iodide aqueous solution or an alkaline earth metal iodide aqueous solution to adsorb free iodine.

  Examples of the organic solvent include ester solvents, aromatic hydrocarbon solvents, and ether solvents.

  As the ester solvent, ethyl acetate, isopropyl acetate, butyl acetate, amyl acetate, hexyl acetate or the like is preferably used. As the aromatic hydrocarbon solvent, benzene, toluene, xylene, ethylbenzene, diethylbenzene or the like is used. As the ether solvent, i-propyl ether, butyl ether, methyl t-butyl ether or the like is preferably used. If not miscible with water, a ketone solvent or an alcohol solvent may be used. These solvents can be used alone or in admixture of two or more. The organic solvent may be removed by adding free iodine to the organic solvent by adding it to an alkali metal iodide aqueous solution or an alkaline earth metal iodide aqueous solution and shaking.

  Further, the alkali metal iodide solution or alkaline earth metal iodide solution obtained in the above reaction step may be concentrated to produce an alkali metal iodide suspension or alkaline earth metal iodide suspension. .

  The alkali metal iodide solution, the alkaline earth metal iodide solution, the alkali metal iodide suspension, or the alkaline earth metal iodide suspension obtained in the above reaction step is the alkali metal iodide according to the present invention or It is suitably used in a method for producing an alkaline earth metal iodide.

(Modification)
In one variation, in the reaction step, for example, the following reaction may be performed using alcohol as a solvent.

(Here, M is an alkali metal or an alkaline earth metal. X ′ is an ion that forms a salt with an alkali metal ion or an alkaline earth metal ion. Also, n is either 1 or 2. X ′ is preferably a hydroxide ion or an acetate ion, and R ¹ is an alkyl group having 1 to 9 carbon atoms, and R ² is, for example, a methyl group .)
[Removal grinding process]
In the removing and grinding step, an alkali metal iodide solution, an alkaline earth metal iodide solution, an alkali metal iodide suspension, or an alkali metal iodide solution or alkaline earth metal iodide solution dissolved or suspended in a solvent While removing the solvent from the alkaline earth metal iodide suspension, the alkali metal iodide or alkaline earth metal iodide is pulverized. Thereby, powdery alkali metal iodide or alkaline earth metal iodide can be easily obtained. Thereby, industrial production of powdered alkali metal iodide or alkaline earth metal iodide becomes possible.

  The removing and pulverizing step is performed by, for example, an alkali metal iodide solution or alkaline earth iodide in which an alkali metal iodide or an alkaline earth metal iodide is dissolved or suspended in a solvent in a container equipped with a rotary blade. While removing the solvent from the metal solution, alkali metal iodide suspension, or alkaline earth metal iodide suspension, the rotor blades are rotated to rotate the alkali metal iodide or alkaline earth iodide in the solution or suspension. This is done by crushing a similar metal. Examples of the material of the container and the rotor blade used for pulverization include SUS, hastelloy, glass lining, ceramic, titanium, and the like, and titanium is particularly preferable.

  In particular, the rotating blade is preferably one that rotates so as to scrape off the solid matter adhering to the inner surface of the container. As described above, solid alkali metal iodide or alkaline earth metal iodide obtained by cooling after concentration is easy to fix to the container, and powdered alkali metal iodide or alkaline earth metal iodide can be obtained. Although it is difficult to industrially produce powdered alkali metal iodide or alkaline earth metal iodide, it is difficult to industrially produce alkali metal iodide or alkaline earth metal iodide. By scraping off the alkaline earth metal crystals, it is possible to prevent the alkali metal iodide or the alkaline earth metal iodide from adhering to the container. Thereby, powdery alkali metal iodide or alkaline earth metal iodide can be easily obtained, and powdered alkali metal iodide or alkaline earth metal iodide can be produced industrially. .

  The pulverization of the alkali metal iodide or alkaline earth metal iodide is carried out by scraping and knocking off the alkali metal iodide or alkaline earth metal iodide crystals adhering to the inner surface of the container. The container may further include a rotor blade for crushing alkali metal iodide or alkaline earth metal iodide separately from the rotor blade.

  Examples of the commercially available apparatus provided with the container and the rotary blade include a pulverization type concentrating dryer (Triple Master, manufactured by Shinagawa Kogyo), a thin film evaporator (high evaporator, manufactured by Sakai Seisakusho), and the like. . In addition, there is no example that reports that powdered alkali metal iodide or alkaline earth metal iodide can be obtained by drying alkali metal iodide or alkaline earth metal iodide using these devices. do not do.

  The rotational speed of the rotor blade for scraping off the solid matter adhering to the inner surface of the container is preferably in the range of 1 rpm to 10,000 rpm, more preferably in the range of 10 rpm to 5000 rpm. By setting the pressure within the range of 20 rpm to 1500 rpm, powdery alkali metal iodide or alkaline earth metal iodide can be obtained successfully.

  And by the removal grinding | pulverization process, it is preferable that the particle diameter of an alkali metal iodide or an alkaline earth metal iodide shall be 5 mm or less, and it is more preferable to set it as 2 mm or less. By setting the particle diameter of the alkali metal iodide or alkaline earth metal iodide within the above range, the amount of the solvent contained in the powdered alkali metal iodide or alkaline earth metal iodide can be suppressed in a short time. it can.

  The removing and pulverizing step is preferably performed at a temperature of 200 ° C. or higher and 350 ° C. or lower, and more preferably 250 ° C. or higher and 300 ° C. or lower. By carrying out the removal pulverization step at 200 ° C. or higher, the amount of the solvent contained in the powdered alkali metal iodide or alkaline earth metal iodide is suppressed, and the powdered alkali metal iodide or iodine containing less solvent is contained. An alkaline earth metal can be obtained. By performing the removing and pulverizing step at 350 ° C. or lower, it is possible to suppress the release of iodine from the alkali metal iodide or the alkaline earth metal iodide.

  More preferably, the removing and pulverizing step is performed under reduced pressure. Thereby, the solvent removal temperature of the alkali metal iodide solution, the alkaline earth metal iodide solution, the alkali metal iodide suspension, or the alkaline earth metal iodide suspension in the removal pulverization step can be lowered. Further, by lowering the solvent removal temperature, it is possible to suppress the liberation of iodine due to decomposition of alkali metal iodide or alkaline earth metal iodide.

  When the solvent removal temperature of the alkali metal iodide solution, alkaline earth metal iodide solution, alkali metal iodide suspension or alkaline earth metal iodide suspension is lowered in the removal grinding step, powdered iodide The amount of the solvent contained in the alkali metal or alkaline earth metal iodide increases. On the other hand, in the removal pulverization step, the solvent removal temperature at which the solvent is removed from the alkali metal iodide solution, alkaline earth metal iodide solution, alkali metal iodide suspension, or alkaline earth metal iodide suspension under reduced pressure conditions. Is reduced, the amount of the solvent contained in the powdered alkali metal iodide or alkaline earth metal iodide can be suppressed. Therefore, the amount of the solvent contained in the powdered alkali metal iodide or alkaline earth metal iodide is suppressed even when the solvent removal temperature is lowered by performing the removal pulverization step under reduced pressure conditions. be able to.

  Alkali metal iodide or alkaline earth metal iodide may react with oxygen contained in the air to release iodine. However, the contact between the air and the alkali metal iodide or the alkaline earth metal iodide is suppressed by performing the removing and pulverizing step under a reduced pressure condition. Therefore, release of iodine can be suppressed.

  A preferable pressure reduction condition when performing the removing and pulverizing step is preferably 30 kPa or less, and more preferably 15 kPa or less. Even when the solvent removal temperature is lowered by performing the removal pulverization step under a reduced pressure condition of 30 kPa or less, the amount of the solvent contained in the alkali metal iodide or the alkaline earth metal iodide is suitably suppressed. Can do. By carrying out the removal pulverization step under a reduced pressure condition of 15 kPa or less, the amount of the solvent contained in the alkali metal iodide or alkaline earth metal iodide is suitably suppressed even when the solvent removal temperature is lowered. be able to.

  The removing and pulverizing step is preferably performed at a temperature of 100 ° C. or higher and 350 ° C. or lower, and more preferably 120 ° C. or higher and 300 ° C. or lower, under reduced pressure conditions. By carrying out the removal pulverization step at 100 ° C. or higher, the amount of the solvent contained in the powdered alkali metal iodide or alkaline earth metal iodide is suppressed, and the alkali metal iodide or alkaline earth metal iodide is suitable. It is possible to remove the solvent. By performing the removing and pulverizing step at 350 ° C. or lower, it is possible to suppress the release of iodine from the alkali metal iodide or the alkaline earth metal iodide.

  More preferably, the removing and pulverizing step is performed in the presence of an inert gas. The inert gas is not limited as long as the gas has a low oxygen content or does not contain oxygen. Examples of the gas not containing oxygen include nitrogen gas and argon gas. Thereby, reaction of oxygen and alkali metal iodide or alkaline earth metal iodide can be suppressed, and release of iodine can be suppressed.

  The method for producing an alkali metal iodide or alkaline earth metal iodide according to the present invention is an industrially feasible and efficient production method, and is a powdery alkali metal iodide or alkali iodide excellent in handling. Earth metal can be provided.

  Moreover, the alkali metal iodide or alkaline earth metal iodide having a solvent content of 1% or less can be obtained by the method for producing an alkali metal iodide or alkaline earth metal iodide according to this embodiment described above. .

  Examples will be shown below, and the embodiments of the present invention will be described in more detail. Of course, the present invention is not limited to the following examples, and it goes without saying that various aspects are possible in detail. Further, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and the present invention is also applied to the embodiments obtained by appropriately combining the disclosed technical means. It is included in the technical scope of the invention. Moreover, all the literatures described in this specification are used as reference.

[Production of lithium iodide]
As described in the following Examples and Comparative Examples, lithium iodide was produced, and the water content of the reaction solution, the purity of lithium iodide, and the water content in the crystals were measured by the following methods.

[Method for measuring purity of lithium iodide]
A sample of lithium iodide was weighed into a 200 ml beaker, and ultrapure water was added to make 100 ml, followed by titration with a potentiometric titrator using a 0.1 M aqueous silver nitrate solution. The iodine ion concentration obtained from the titration result was converted to a lithium iodide concentration to obtain lithium iodide purity.

[Method for measuring water content in crystal and solution]
Measurement was performed using a volumetric Karl Fischer moisture meter.

[Production example]
6500.0 g of ion-exchanged water was charged into the reaction vessel from the dropping funnel of a 20 L reaction vessel equipped with a stirrer, a thermometer, a pH meter, a dropping funnel and a solid charging port. Under stirring, 2500.0 g (33.8 mol) of lithium carbonate was charged from the solid charging port. A dropping funnel was charged with 15169.0 g (67.6 mol) of a 57 wt% hydroiodic acid aqueous solution. After the temperature in the reaction vessel was 25 ° C., the hydroiodic acid aqueous solution in the dropping funnel was dropped while maintaining the temperature in the reaction vessel in the range of 25 to 40 ° C. After completion of the dropwise addition, the mixture was stirred for 30 minutes while maintaining the temperature in the reaction vessel at 25 to 30 ° C. to continue aging (reaction process).

  Next, lithium hydroxide was charged from the solid charging port, and the pH in the reaction vessel was adjusted to 5 to 6 to obtain a pH adjusting solution. Next, 73.0 g of activated carbon (Shirakaba A, manufactured by Takeda Pharmaceutical Co., Ltd.) was charged into the pH adjusting solution from the solid charging port, and stirred for 30 minutes while maintaining the temperature in the reaction vessel at 25 to 30 ° C. Thereafter, the contents of the reaction vessel were fed under reduced pressure onto Nutsche equipped with ADVANTEC qualitative filter paper (No. 5C) in a suction bottle, and the activated carbon was filtered to obtain a colorless and transparent aqueous solution of lithium iodide. The lithium iodide concentration in the aqueous solution was 41% by weight.

[Example 1]
An aqueous lithium iodide solution was produced according to the above production example. A pulverization type concentrating dryer (Triple Master, manufactured by Shinagawa Kogyo) equipped with a container having a capacity of 5 L, an inner diameter of φ202 mm and a depth of 160 mm, and a revolution blade, a kneading blade and a crushing blade rotating in the container was prepared. The revolving blade is a rotating blade that rotates so as to scrape off the solid matter adhering to the inner surface of the container, the kneading blade is a rotating blade that generates a shearing force, and the crushing blade is a rotating blade that crushes solid matter. is there. In the container of the pulverization type concentrating dryer, 4.0 kg of the manufactured lithium iodide aqueous solution was charged. The rotation speed of the revolution blade during concentration is 26 rpm, the rotation speed of the kneading blade is 45 rpm, the rotation speed of the crushing blade is 2000 rpm, the rotation speed of the revolution blade during drying is 26 rpm, the rotation speed of the kneading blade is 445 rpm, and the rotation speed of the crushing blade Concentration and drying were performed for 3 hours at 180 ° C./3 kPa at 3900 rpm (removal pulverization step).

  The obtained crystal was powdery, the water content in the crystal was 0.3% by weight, and the purity of lithium iodide in the crystal was 99.1% by weight. The obtained crystals were classified for each particle size using a stainless steel sieve in a glove box substituted with nitrogen. The water content in each distribution and crystal is 6.2%, 0.3% by weight, 90% to 180 μm, 39.9%, 0.3% by weight, 180 μm to 300 μm, 28.6%, and 0.8%, respectively. 5% by weight, 300% to 425 μm 2.2%, 0.9% by weight, 425 μm to 500 μm 1.0%, 1.4% by weight, 500 μm to 2000 μm 10.6%, 0.7% by weight, 2000 μm The above were 11.6% and 0.9% by weight.

[Example 2]
An aqueous lithium iodide solution was produced according to the above production example. A thin film evaporator provided with a cylindrical container having a diameter of 150 mm and a height of 300 mm provided with a heat transfer surface with a heat transfer area of 0.14 m ^{2 on} the inside, and attached to the inner surface (heat transfer surface) of the container A thin-film evaporation dryer (high evaporator, manufactured by Sakai Seisakusho) equipped with a movable blade blade that rotates so as to scrape off the solid material thus prepared was prepared. The movable blade blade presses the treatment liquid that is uniformly dispersed on the heat transfer surface against the heat transfer surface to evaporate the solvent, and strikes and crushes solids adhering to the heat transfer surface. Yes. Using the thin-film evaporation dryer, 2.3 kg of the produced lithium iodide aqueous solution was dried at 240 ° C./14 kPa for 20 minutes at a blade blade rotation speed of 1200 rpm and a liquid feed flow rate of 5 L / h. Crystals were obtained (removal crushing step).

  The water content in the crystal was 0.6% by weight, and the purity of lithium iodide in the crystal was 98.1% by weight. The obtained crystals were classified by the same operation as in Example 1. The respective distributions and moisture in the crystals were not more than 500 μm, 90.3%, 0.4% by weight, 500 μm to 1000 μm, 3.5%, 0.7% by weight, 1000 μm to 2000 μm, 2.2%, It was 4.0% and 0.5% by weight at 8% by weight and 2000 μm or more.

[Comparative Example 1]
An aqueous lithium iodide solution was produced according to the above production example. A rotary tube furnace (manufactured by HC Engineering) containing 2 kg of φ10 mm alumina balls was prepared. Into the rotary tube furnace, 1.0 kg of the produced lithium iodide aqueous solution was put, and while rotating nitrogen gas at a flow rate of 2 L / min, the rotation speed of the furnace was set to 4 rpm, and the temperature was increased from room temperature to 150 ° C. at 15 ° C./min. Concentration was carried out by holding for 30 minutes after warming. Then, after raising the temperature to 300 ° C. and holding for 30 minutes for drying, crystals fixed to the furnace wall surface were obtained. The water in the crystal was 9.2% by weight, the purity of lithium iodide was 88.9% by weight, and the obtained crystal was lithium iodide monohydrate.

[Comparative Example 2]
An aqueous lithium iodide solution was produced according to the above production example. A conical ribbon mixer / dryer equipped with a ribbon mixing blade (ribocorn, manufactured by Okawara Seisakusho) was prepared. 13.8 kg of the produced lithium iodide aqueous solution was put into the conical ribbon mixing dryer, and the ribbon mixing blade rotation speed was set to 130 rpm, and concentration was performed at 150 ° C./1.7 kPa. Distillation stopped when concentrated for 5 hours. When the obtained aqueous solution was cooled to room temperature, it became a fixed crystal. The water in the crystal was 11.9% by weight, the purity of lithium iodide in the crystal was 87.7% by weight, and the obtained crystal was lithium iodide monohydrate.

[Reference experiment]
[Relationship between film thickness and moisture content]
An aqueous lithium iodide solution was produced according to the above production example. The lithium iodide aqueous solution of the amount to be described later is put into a 50 mL eggplant type flask, water is distilled off at 50 ° C./3 kPa for 1 hour while rotating with an evaporator, and then the vacuum pump is stopped in rotation. Was further concentrated to dryness at 120 ° C./0.4 kPa over 2 hours to obtain white crystals. When the charged amount of the lithium iodide aqueous solution was 5 mL, the moisture in the obtained crystal was 13.3% by weight, and the film thickness of the crystal was 3.6 mm. In the same operation, when the charged amount of the lithium iodide aqueous solution was 2 mL, the water in the obtained crystal was 3.3% by weight, and the film thickness of the crystal was 2.0 mm. In the same operation, when the charged amount of the lithium iodide aqueous solution was 0.5 mL, the water in the obtained crystal was 1.0% by weight, and the film thickness of the crystal was 0.6 mm.

[Examination of thin film drying]
The thin film drying of lithium iodide aqueous solution was examined.

(Experimental conditions)
Top plate: 9cmφ aluminum dish, location: in the draft, preparation: 10ml LiI aqueous solution
The conditions and results for thin film drying are listed in the table below.

  The removal by total drying (evaporator, 200 ° C., 0.4 kPa drying, repeated pulverization) was very poor in operability. When the volume of the liquid (crystal) is high, pulverization is required, and thin film drying is preferable in small portions.

[Material examination 1]
The material of the instrument used for drying was examined.

(Experimental conditions)
Top plate: Petri dish or dish of various materials of 8-9 cmφ, location: in a draft, preparation: 5 ml of LiI aqueous solution, dried at 200-300 ° C. Materials and results are listed in the table below. L indicates that it is below the detection limit.

  When the top plate contains aluminum or iron, it mixed into the crystal. It has been found that titanium is preferable as the material used for drying the heat transfer thin film.

[Material examination 2]
It was verified that titanium is preferred as the material of the instrument for drying.

(Experimental conditions)
Top plate: Ti Petri dish of 9cmφ, Place: In the draft, Preparation: 5ml LiI aqueous solution
The drying conditions and results are listed in the table below.

  As shown, white crystals with a moisture content of 1-2% and a purity of 99.0% were obtained.

[Examination of drying temperature]
The drying temperature of the lithium iodide aqueous solution was examined.

(Experimental conditions)
Top plate: 9 cmφ Ti petri dish, location: in the draft, preparation: 5 ml of LiI aqueous solution
The table temperature and the time required for drying are described in the following table.

  When the top plate temperature was 200 ° C., the drying proceeded only to a slightly moist state even if the drying was continued for 3 hours or more.

  When the top plate temperature was 250 ° C., the drying proceeded by continuing the drying for 60 minutes, and lithium iodide was almost crystallized. Further, although drying was continued for 140 minutes, no particular change was observed in lithium iodide.

  When the top temperature was 280 ° C., the drying progressed by continuing the drying for 10 minutes, and lithium iodide was almost crystallized. However, the generation of purple smoke (iodine liberation and decomposition) was confirmed by continuing drying for 30 minutes.

  When the top plate temperature was 300 ° C., the drying progressed by continuing the drying for 4 minutes, and lithium iodide was almost crystallized. However, the generation of purple smoke was confirmed by continuing to dry for 8 minutes. Moreover, a part of lithium iodide which was a white crystal was slightly thin and yellowish.

  From these results, it was found that when drying was continued at a high temperature, overdrying occurred and lithium iodide was decomposed (iodine liberation).

[Examination of thermal stability 1]
Next, the thermal stability of the lithium iodide aqueous solution in the atmosphere was examined.

(Experimental conditions)
Top plate: 9 cmφ Ti petri dish, place: in the draft (normal pressure, 300 ° C.), preparation: 5 ml of 42% LiI aqueous solution (3 g in terms of solid content)
The drying time and LiI (lithium iodide) purity are listed in the table below.

  In addition, the thermal stability of lithium iodide crystals in the atmosphere was also examined.

(Experimental conditions)
Top plate: 9 cm φ Ti petri dish, location: in the draft (normal pressure, 300 ° C.), preparation: 3 g LiI crystal
The drying time, LiI purity and moisture (KF) are listed in the table below.

  It was found that when the lithium iodide aqueous solution and the lithium iodide crystal were dried at 300 ° C., the LiI purity decreased with time and lithium iodide was decomposed (iodine liberation).

[Examination of thermal stability 2]
Next, the thermal stability of lithium iodide crystals in an inert gas (nitrogen) was examined.

(Experimental conditions)
Top plate: 9 cmφ Ti petri dish, location: Globe Books (under N ₂ stream, 300 ° C.), preparation: LiI crystal 5 g
The drying time, LiI purity and moisture (KF) are listed in the table below.

The LiI crystal was heated for 60 minutes under N ₂ atmosphere, but no purple smoke was generated.
In addition, the quality of the LiI crystal did not decrease, such as a decrease in LiI purity or an increase in moisture value.

In addition, it is thought that LiI crystal | crystallization is decomposed | disassembled with the water or oxygen contained in the air, and the said decomposition | disassembly can be represented with the following chemical formula.
4LiI + O ₂ → 2Li ₂ O + 2I ₂ ↑ (1)
Li ₂ O + H ₂ O → 2LiOH (2)
In this experiment, since the LiI crystal was dried in an inert gas, the LiI purity did not decrease. Therefore, it was concluded that the reaction of the formula (1) or (2) does not occur in the inert gas, and the release of iodine can be suppressed.

[Examination of thermal stability 3]
Next, the thermal stability of the lithium iodide crystal when water was supplied in an inert gas (nitrogen) was examined.

(Experimental conditions)
Top plate: 9 cmφ Ti petri dish, location: Globe Books (under N ₂ air current, 300 ° C., the surroundings are wetted by spraying as needed), preparation: LiI crystal 4 g
The drying time, LiI purity and moisture (KF) are listed in the table below.

The LiI crystal was heated for 60 minutes under N ₂ atmosphere, but no purple smoke was generated.
In addition, the quality of the LiI crystal did not decrease, such as a decrease in LiI purity or an increase in moisture value.

  Therefore, it was concluded that the water did not affect the decomposition of the LiI crystal and the reaction of the above formula (2) did not occur in this experiment.

[Examination of thermal stability 4]
Next, the thermal stability of the lithium iodide crystal at temperatures exceeding 300 ° C. in an inert gas (nitrogen) was confirmed.

(Experimental conditions)
Top plate: 9 cmφ Ti petri dish, location: Globe Books (under N ₂ airflow, 390-450 ° C.), preparation: LiI crystal 4 g
After confirming that the top plate temperature was around 390 ° C. with a thermocouple, purple smoke was generated from the crystals as soon as a lithium iodide crystal was placed. Thereafter, a part of the lithium iodide crystal became a crystal that seemed to be iodine, and violet smoke was vigorously generated. Therefore, the experiment was completed in 4 minutes from the start. The top plate temperature at the end was increased to around 440 ° C.

  Therefore, it was concluded that the decomposition of lithium iodide crystals occurs if the drying temperature is high even under a nitrogen atmosphere.

[Examination of vacuum drying 1]
Next, water was distilled off under reduced pressure (3 kPa) and dried at the following temperatures for 2 hours.

(Experimental conditions)
Evaporator (3 kPa), charge: 5 ml of 40% LiI aqueous solution
The results when the aqueous lithium iodide solution was dried at each temperature are shown in the following table.

  As shown in the table, the drying temperature became almost anhydrous at 180 ° C. In this experiment, it was concluded that the lithium iodide aqueous solution could be dried at a lower temperature because the pressure was lower than the pressure in the above “examination of drying temperature”.

[Examination of vacuum drying 2]
Next, water was distilled off under reduced pressure (0.4 kPa) more than in Study 1 of reduced pressure drying, and dried at the following temperatures for 20 minutes to 3 hours.

(Experimental conditions)
Evaporator (0.4 kPa), preparation: 40% LiI aqueous solution 5 ml
The results when the aqueous lithium iodide solution was dried at each temperature are shown in the following table.

  When the drying temperature was 120 ° C. and the pressure was 0.4 kPa, the moisture value was 1.0%, but when the pressure was 3 kPa, the moisture value was 22.3%. Therefore, it was concluded that by reducing the pressure, the amount of moisture value of the lithium iodide crystal decreased, and the aqueous lithium iodide solution could be dried at a lower drying temperature.

  The present invention can be suitably used, for example, for producing powdered alkali metal iodide or alkaline earth metal iodide.

Claims (5)

A method for producing an alkali metal iodide or alkaline earth metal iodide for producing powdered alkali metal iodide or alkaline earth metal iodide,
An alkali metal iodide solution, an alkaline earth metal iodide solution, an alkali metal iodide suspension or an alkaline earth iodide in which an alkali metal iodide or an alkaline earth metal iodide is dissolved or suspended in a solvent A method for producing an alkali metal iodide or alkaline earth metal iodide, comprising a removing and pulverizing step of pulverizing the alkali metal iodide or alkaline earth metal iodide while removing the solvent from the metal suspension.   In the removing and pulverizing step, the solid matter adhered to the inner surface of the container containing the alkali metal iodide solution, alkaline earth metal iodide solution, alkali metal iodide suspension or alkaline earth metal iodide suspension is removed. 2. The alkali metal iodide or alkaline earth metal iodide according to claim 1, wherein the solvent is removed and the alkali metal iodide or the alkaline earth metal iodide is pulverized while being scraped off by a rotary blade. Production method.   3. The alkali metal iodide or iodine according to claim 1, wherein a particle diameter of the powdered alkali metal iodide or alkaline earth metal iodide obtained by the removing and pulverizing step is 5 mm or less. Of producing alkaline earth metal.   The alkali metal iodide solution, alkaline earth metal iodide solution, alkali metal iodide suspension, or alkaline earth metal iodide suspension is an alkali metal compound or alkaline earth metal compound and iodide. It is produced | generated by the reaction process made to react in, The manufacturing method of the alkali metal iodide or alkaline-earth metal iodide as described in any one of Claims 1-3 characterized by the above-mentioned.   The method for producing an alkali metal iodide or alkaline earth metal iodide according to claim 4, wherein the solvent used in the reaction step is water.