JP2019089673A - Method for producing inorganic iodine anhydrous compound and lump thereof - Google Patents

Abstract

To provide a method for producing an inorganic iodine anhydrous compound that achieves a high collection rate.SOLUTION: A method for producing an inorganic iodine anhydrous compound is provided which comprises a water removal step of irradiating a composition containing an inorganic iodine compound and water with microwave under reduced pressure conditions thereby evaporating water from the composition to remove the composition of water.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a process for producing inorganic iodine compound anhydrides, and to lumps.

  Heretofore, inorganic iodine compounds have been used in various fields as chemical raw materials, raw materials for producing pharmaceuticals, and the like. For example, sodium iodide is an inorganic iodine compound that is used widely in the manufacturing process of medicines and agrochemicals. In addition, lithium iodide is an inorganic iodine compound that is used in all solid lithium batteries, dye-sensitized solar cells, etc., and is attracting attention in recent years.

  Here, in general, many inorganic iodine compounds have high hygroscopicity and deliquescent properties. In addition, many crystals having water of crystallization exist. However, in non-aqueous applications, inorganic iodine compounds from which water is sufficiently removed are desired.

  As a method of drying an inorganic iodine compound and removing moisture, many methods conventionally known, for example, a method of heating a solid inorganic iodine compound can be mentioned (Non-patent documents 1 to 3). Other than that, for example, methods of removing water by extracting or azeotroping water of crystallization contained in an inorganic iodine compound using an organic solvent have been proposed (Patent Documents 1 and 2). There is also proposed a method of removing water by drying a water-containing salt or an aqueous solution of lithium iodide (Patent Documents 3 and 4). Furthermore, since a solid after drying is easily fixed to a container, a method of removing water while using a stirring blade for scraping the wall has also been proposed (Patent Document 5).

JP 2013-256416 A JP, 2015-157743, A JP, 2013-103851, A JP, 2015-214472, A JP, 2015-137214, A

Iodine speculation, Shigagaseki publication, Keiichiro Matsuoka, February, 1974 issue New Experimental Science Course, Volume 8, edited by The Chemical Society of Japan, 1997, pp. 462-463 Laboratory Science, 5th Edition, Vol. 23, Inorganic compounds, p. 322

  However, in the methods using the organic solvent described in Patent Documents 1 and 2, there is a need to use and manage a large amount of alcohol when carrying out production, and there are drawbacks from the viewpoint of equipment used and cost.

  In addition, in many cases, the inorganic iodine compound is synthesized by a liquid phase reaction, and thus the synthesized inorganic iodine compound is obtained as an aqueous solution. Therefore, a method of directly removing the water from the aqueous solution of the inorganic iodine compound to obtain a dried solid of the inorganic iodine compound directly is desired, but in this case, the aggregate where the precipitated inorganic iodine compound is firmly fixed to the side wall and bottom of the container It will be formed. Although the fixed inorganic iodine compound can be recovered to some extent using, for example, the rotary blade of Patent Document 5, the particles of the inorganic iodine compound have a very high hardness, so the stirring blade easily wears rapidly, which is sufficient. Recovery rate can not be obtained. Furthermore, there is a possibility that impurities may be mixed into the product due to the abrasion of the stirring blade, etc., and it is difficult to manufacture with stable quality.

  As described in Non Patent Literatures 1 to 3 and Patent Literatures 3 and 4, even in the case of heating solid inorganic iodine compounds, when a solid containing a large amount of water, such as a hydrate, is heated, the heating is underway. Re-dissolution of the solid occurs. When water is to be removed from the redissolved solid, aggregates are formed in which the inorganic iodine compound deposited similarly to the case of the aqueous solution is firmly fixed to the side wall and the bottom of the container.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for producing an inorganic iodine compound anhydride having a high recovery rate.

  The method for producing an inorganic iodine compound anhydride of the present invention comprises a step of removing water from the composition by evaporating water by irradiating the composition containing the inorganic iodine compound and water with microwaves under reduced pressure conditions. Prepare.

  It is preferable that the said inorganic iodine compound is a thing in which the polymorphism containing crystal water exists.

  The above composition is preferably an aqueous solution of an inorganic iodine compound.

  The inorganic iodine compound is preferably sodium iodide or lithium iodide.

  The water removal step is preferably performed until the temperature of the composition decreases at least monotonically with respect to the irradiation time when the microwave of constant output is irradiated.

  The lump of the present invention is one in which particles of a plurality of inorganic iodine compound anhydrides are integrated, and the breaking strength is 100 N or less.

  According to the present invention, it is possible to provide a method for producing an inorganic iodine compound anhydride having a high recovery rate.

FIG. 1 is a schematic view for explaining the change in temperature of the composition with respect to the irradiation time.

  The method for producing an inorganic iodine compound anhydride of the present embodiment comprises a step of removing water by evaporating water from the composition by irradiating the composition containing the inorganic iodine compound and water with microwaves under reduced pressure conditions. Equipped with

  The composition is not particularly limited as long as it contains an inorganic iodine compound and water, but an aqueous solution of an inorganic iodine compound, a hydrate of an inorganic iodine compound, a mixture of inorganic iodine compound solid and water, etc. may be mentioned. . The content of water in the composition is not particularly limited, but may be 44 to 99% by mass with respect to the total amount of the composition.

  In the embodiment, the inorganic iodine compound anhydride is an inorganic iodine compound solid substantially free of water (including water in the form of water of crystallization), and, for example, in the total amount of inorganic iodine compound anhydride On the other hand, the water content is preferably 0.1% by mass or less. The lower limit of the water content is not particularly limited, but can be 10 ppm.

  It is preferable that the content (purity) of the target inorganic iodine compound is 99.0 mass% or more with respect to the total amount of the inorganic iodine compound anhydride. In addition, inorganic iodine compound anhydride may contain the unavoidable impurity derived from raw materials etc. in addition to the target inorganic iodine compound and a trace amount of water, and the content of the unavoidable impurity is, for example, 0.1 mass% or less It is preferable that Examples of the impurities include calcium ions, iron ions, magnesium ions, and sodium ions as metal ions other than metals possessed by anions such as chloride ion, bromide ion, and sulfate ion and the target inorganic iodine compound anhydride.

The content of the inorganic iodine compound in the inorganic iodine compound anhydride and the water content can be measured by the following method.
[Content analysis]
The iodine content in the inorganic iodine compound anhydride can be determined by quantifying the iodide ion concentration with an automatic titrator that captures the change in potential with a potassium iodate standard solution and converting it to the concentration of the inorganic iodine compound to determine the content it can. In addition, this analysis method is a method according to JISK8913 of potassium iodide (reagent).
Further, impurities such as metal impurities can be determined by analysis using high frequency inductively coupled plasma emission spectroscopy (ICP emission spectroscopy).
[Measuring method of moisture]
In the case of lithium iodide, it can be introduced by the vaporization method (280 ° C.) in which the vaporization device is combined with the Karl Fischer moisture measurement device of Kyoto Electronics Industries Ltd., and it can be determined by the coulometric titration method. The water content is preferably 0.1% by mass or less based on the total weight of the obtained inorganic iodine compound.
In the case of sodium iodide, it can be determined by measurement by a coulometric titration method by a direct method using a Karl Fischer moisture measurement device of Kyoto Electronics Industries Ltd. The water content is preferably 0.1% by mass or less based on the total weight of the obtained inorganic iodine compound.

  The inorganic iodine compound in the present embodiment is not particularly limited, but is preferably a metal iodide salt. Examples of the metal contained in the metal iodide salt include alkali metals, alkaline earth metals, transition metals, and metals of p-block in the periodic table.

  Among the above-mentioned inorganic iodine compounds, there are those in which there is a polymorph having crystal water. As an inorganic iodine compound in which there exist polymorphs containing crystal water, aluminum iodide, calcium iodide, cobalt iodide, strontium iodide, cerium iodide, iron iodide, iron iodide, sodium iodide, barium iodide, magnesium iodide And 11 types of manganese iodide and lithium iodide. As the inorganic iodine compound of the present embodiment, alkali metal iodide salts which are particularly frequently used in industry are preferable, and sodium iodide or lithium iodide is particularly preferable.

  When an alkali metal iodide salt is used as the inorganic iodine compound, as a method for producing the alkali metal iodide salt, for example, an aqueous solution of iodine and an alkali metal hydroxide salt is reacted using formic acid which is an organic reducing agent Two methods (Method 1) and methods (Method 2) obtained by the neutralization reaction of an alkali metal carbonate and hydroiodic acid can be employed.

Taking lithium iodide as an example, in the case of the formic acid method of Method 1, while an aqueous solution of lithium hydroxide is being stirred, iodine and formic acid are added and reacted. The reaction formula is represented by the following formula.
I ₂ + 2LiOH + HCOOH → 2LiI + CO ₂ + 2H ₂ O
The temperature in the reactor is preferably in the range of 60 to 110 ° C., and particularly preferably in the range of 80 to 100 ° C. because of the easiness of production. When the temperature is 60 ° C. or more, the reaction rate of iodine and formic acid is sufficiently high, and when it is 110 ° C. or less, the loss due to sublimation of iodine is reduced.

  Moreover, in the above reaction, it is preferable to adjust the pH of the obtained lithium iodide aqueous solution. The pH after adjustment is adjusted preferably in the range of 5 to 9, more preferably 6 to 8. As a pH adjuster, lithium hydroxide or hydroiodic acid in the reaction step can be used.

  Since the lithium iodide aqueous solution after reaction is slightly colored by liberated iodine, it is preferable to adopt a method of adsorbing liberated iodine with a porous adsorbent. Although known materials such as zeolite can be used as the porous adsorbent, it is preferable to use activated carbon which has been pretreated by acid washing and then washed with water. Thereby, free iodine is adsorbed, and the resulting solution can be obtained as an almost colorless solution in which free iodine in the solution is 0.2% by mass or less. In addition, it is possible to add a reducing agent such as a phosphorus compound such as hypophosphorous acid, a sulfur compound such as sulfurous acid, or a hydrazine compound to the reaction solution as a stabilizer, but this is not added because impurities increase. Is preferred.

In addition, the reaction of method 2 uses lithium carbonate described in Non-Patent Document 1 as a lithium source and carries out a neutralization reaction with hydroiodic acid. A solution of 57% by mass can be used as a commercial product as hydroiodic acid which is a raw material. Although hydroiodic acid can be used even at low concentrations, those in the range of 20 to 58% by mass are preferable so that the concentration of lithium iodide obtained is not too low. Moreover, it is preferable to set it as the range of 20-60 w / v%, and, as for the density | concentration of lithium carbonate aqueous solution, the density | concentration of 55-60 w / v% is more preferable. Moreover, in order to suppress the generation | occurrence | production of free iodine, it is preferable to carry out on inert gas conditions like nitrogen gas or argon gas. The reaction formula of this reaction is as follows.
Li ₂ CO ₃ +2 HI → ₂ Li I + CO ₂ + H ₂ O

  Since heat is generated due to the neutralization of acid and alkali, and carbon dioxide gas is also generated, hydroiodic acid is dropped and reacted while carefully maintaining the temperature range of 30 to 50 ° C. while stirring.

  Next, the pH in the reaction vessel is confirmed while maintaining the temperature at 30 ° C., and pH adjustment is performed with an acid or alkaline solution, but the concentration of the aqueous solution to be used may be appropriately selected. It is preferable to add a hydrogen acid, and if it is acidic, adjust the pH to 6.0 to 9.0 by adding a powder or an aqueous solution of lithium hydroxide. Thereby, a colorless lithium iodide solution can be obtained.

  The aqueous solution of the inorganic iodine compound can be prepared by dissolving the inorganic iodine compound in water. Moreover, you may use the aqueous solution of the inorganic iodine compound obtained by said method 1, 2 grade | etc., As it is. Here, the aqueous solution may contain formic acid used as a reaction raw material, an organic solvent used as a reaction solvent, and an organic substance as an antioxidant. Furthermore, in order to suppress the generation of free iodine due to the oxidation of iodide ion, the solution contains, for example, a phosphorus compound such as hypophosphorous acid, a sulfur compound such as sulfite, and a reducing agent such as hydrazine as a stabilizer. Also good. However, the content of the organic substance, the organic solvent and the stabilizer is preferably 10% by mass or less, and it is more preferable that the organic substance, the organic solvent and the stabilizer are not substantially included.

  In the water removing step of the present embodiment, the composition is heated by microwave irradiation, and water contained in the composition is evaporated and removed. Since such a water removal step is included, in the production method of the present embodiment, a solid of the inorganic iodine compound can be obtained at a high recovery rate. Although this is not necessarily clear about this reason, this inventor thinks as follows.

  First, in the conventional drying method of an inorganic iodine compound, indirect heating has been used in which a composition containing the inorganic iodine compound and water is heated by a heating medium such as an electric heater or hot air. In indirect heating, heat from the heat medium is gradually conducted to the inside of the container through the side wall and the bottom of the container, so a temperature gradient is generated near the inner surface (bottom, side, etc.) of the container and inside the container. Therefore, when an aqueous solution of an inorganic iodine compound is used as the above composition, precipitation of crystals of the inorganic iodine compound locally and rapidly starts near the inner surface of the container during heating, so that the crystals fuse together, Aggregates adhere to the inner surface of the container with a large surface area. Such aggregate adheres firmly to the inner surface of the container and has high hardness, so it is difficult to break and scrape off the surface of the container, leading to a decrease in recovery rate.

  Moreover, when the hydrate of an inorganic iodine compound is used as said composition, the concentrated mixture which the hydrate re-dissolved during heating is obtained. Such concentrated mixtures are difficult to remove by conventional indirect heating because of their boiling point rise. Further, as in the case of the aqueous solution, when water is removed from the concentrated mixture by indirect heating, crystals of the inorganic iodine compound precipitate again to form the above-mentioned aggregate.

  On the other hand, in the water removal step of the present embodiment, the composition is heated by microwave irradiation (microwave heating). Microwave heating is direct heating in which a dipole such as a water molecule rapidly generates heat by following the oscillation of the electric field of the microwave at high speed.

  Microwave heating, which is direct heating, has features different from indirect heating, and examples thereof include (1) internal heating, (2) high-speed heating, and (3) selective heating. Since the microwave can enter the inside of the object to be heated, the whole material generates heat uniformly (internal heating). Further, since the substance to be heated is directly heated, the time for heat diffusion due to heat conduction and the like can be ignored, and high-speed heating can be realized. Furthermore, since the degree of absorbing microwaves differs depending on the substance, selective heating can be performed to heat only what is desired to be heated.

  Therefore, unlike indirect heating, in direct heating by microwaves, precipitation of crystals starts substantially uniformly not only near the inner surface of the container but also from the entire composition. Therefore, the precipitated crystals are less likely to adhere to the inner surface of the container, and the grown crystals partially contact their surfaces for integration. Thereby, the solid of the inorganic iodine compound is easily obtained in the form of a lump in which particles of a plurality of inorganic iodine compound anhydrides are integrated. In addition, since such a lump is porous and soft, it can be easily scraped off even if it adheres to the inner surface of the container. Moreover, according to the manufacturing method of this embodiment, water can be efficiently evaporated by said (1)-(3).

  The breaking strength of the lump is preferably 100 N or less, more preferably 10 to 60 N. Here, the breaking strength can be measured by cutting a substantially spherical sample having a diameter of about 15 mm from a block, and using a wooden house hardness tester 043019-A manufactured by Fujiwara Manufacturing Co., Ltd.

Moreover, as a bulk density of the said lump, it is preferable that it is 1.00 g / cm < ³ > or less, for example, and it is preferable that it is 0.50-0.60 g / cm < ³ >. As a measuring method of bulk density, the bulk density measuring method of the granulated material of the Japan powder industry technology association plan SAP01-79 is mentioned.

  The water removal step is preferably performed until the temperature of the composition decreases at least monotonically with respect to the irradiation time when the microwave of constant output is irradiated. The temperature change of the composition with respect to the irradiation time will be described with reference to FIG. In FIG. 1, the vertical axis represents the temperature (arbitrary unit) of the composition, and the horizontal axis represents the microwave irradiation time. When the composition is irradiated with microwaves at a constant output, water contained in the composition initially absorbs the microwaves and the temperature of the composition rises. However, when the amount of water contained in the composition decreases, the amount of absorption of microwaves in the composition decreases, so the amount of heat released from the composition to the outside such as the atmosphere becomes larger. Therefore, the temperature of the composition takes a maximum value at the irradiation time t1. After the irradiation time t1, the temperature of the composition monotonously decreases with respect to the irradiation time.

  In other words, in a region where the temperature of the composition monotonously decreases with respect to the irradiation time (that is, a region where the irradiation time is longer than t1), the content of water contained in the composition tends to be sufficiently reduced. For this reason, it is preferable that the microwave irradiation be performed at least to a region where the temperature of the composition monotonously decreases (that is, after t1 in FIG. 1).

  In addition, after completion of the water removal step, the obtained inorganic iodine compound anhydride is cooled to room temperature. Since the cooling is mainly carried out through the side wall or bottom of the container, the temperature of the inorganic iodine compound anhydride located near the inner surface of the container decreases earlier than that located inside the container. This produces a temperature gradient within the inorganic iodine compound anhydride obtained. At this time, water may move from the inorganic iodine compound solid inside the high-temperature container to the inorganic iodine compound solid near the surface of the container, and partial re-dissolution of the inorganic iodine compound solid may occur near the surface of the container . In this case, liquid crosslinks are formed between the inorganic iodine compound solids, and the redissolved part adheres to the inner surface of the container. Further, as the temperature decreases, a solid bridge is formed between the inorganic iodine compound solid, and the portion of the inorganic iodine compound solid attached to the container is solidified, and the inorganic iodine compound anhydride is fixed on the inner surface of the container. There is a risk of If the microwave irradiation is performed at least until the temperature of the composition monotonously decreases, such re-dissolution and sticking to the inner surface of the container tend to be suppressed, and the recovery rate can be further improved.

  The progress of water removal in the composition during microwave irradiation can also be known by observing the microwave reflected from the composition. For example, when the composition is irradiated with microwaves having a constant output, the intensity of the microwaves reflected from the composition with respect to the irradiation time of the microwaves is substantially monotonous as the water contained in the composition decreases. To increase. When the amount of water contained in the composition is sufficiently reduced, the amount of reflection of microwaves reflected from the composition becomes substantially constant. The water removal step is preferably continued until the amount of reflection of microwaves reflected from the composition becomes substantially constant.

  As a method of measuring the intensity of the microwave reflected from the composition, there is a method of inserting PM10-DM or PM10-BI which is a power monitor manufactured by Micro Electronics Co., Ltd. into a part of the connecting waveguide and measuring it. It can be mentioned.

  After completion of the water removal step, the obtained inorganic iodine compound anhydride is cooled to room temperature. As a cooling method, natural cooling is mentioned.

  There is no restriction | limiting in particular as output of a microwave, Although it can change suitably according to the input amount of the composition which removes water, etc., For example, it is preferable that it is 100-4000W. If the power of the microwave is 100 to 4000 W, the water tends to be removed at a sufficient evaporation rate. Also, the output of the microwave may be constant in the water removal step, but it is also possible to change the output as needed. The frequency of the microwaves is preferably a frequency at which the microwaves are absorbed by water, for example, preferably 24.2 to 24.8 GHz.

  There is no restriction | limiting in particular as temperature of the composition in microwave irradiation, According to the kind etc. of the inorganic iodine compound contained in a composition, you may change suitably. For example, when the inorganic iodine compound is lithium iodide, the temperature of the composition is preferably 80 to 240 ° C. By setting the temperature of the composition to 80 to 240 ° C., coloring by the free iodine which is a thermal decomposition product can be suppressed, and water tends to be removed at a sufficient evaporation rate.

  The irradiation time of the microwave can be appropriately changed according to the output of the microwave, the type of the inorganic iodine compound, and the like, but is preferably 0.1 to 10 hours, and more preferably 1 to 4 hours. Since microwave heating can evaporate water at high speed, the drying time can be shortened.

  The water removal step is performed under reduced pressure conditions. By performing the water removal step under reduced pressure, generation of free iodine by heating in the presence of oxygen tends to be suppressed. The specific pressure in the water removal step is not particularly limited as long as the pressure is lower than atmospheric pressure (for example, 101.325 kPa), but is preferably 0.1 to 10 kPa. In addition, a carrier gas may be flowed to quickly exhaust the water vapor generated by the microwave heating to the outside of the container. The type of carrier gas is not particularly limited as long as it is a dry gas, and an inert gas such as dry air, nitrogen gas, or argon gas can be used.

  The material of the container for containing the inorganic iodine compound during drying is not particularly limited as long as it does not heat or react by microwave irradiation, but a container made of fluorocarbon resin, borosilicate glass, or quartz glass is preferable, Containers made of quartz glass are more preferred.

  The microwave irradiation can be performed, for example, by a microwave dryer. As a microwave dryer, any of a batch type and a continuous type may be used.

  As mentioned above, although embodiment of this invention was described, this invention can be changed in the range of the matter described in this specification, and it is technically possible about the embodiment obtained by combining suitably the disclosed technical means suitably. It is included in the range.

Examples will be shown below, and the embodiment of the present invention will be described in more detail. However, it goes without saying that the present invention is not limited to the contents shown in the embodiments.
Example 1

  Place a container made of quartz glass containing 100.6 g of a colorless and transparent 55.6 mass% lithium iodide aqueous solution in a vacuum microwave dryer manufactured by Micro Electronics Corporation, and use a vacuum pump to set the inside of the chamber to 5.3 kPa Depressurized. Thereafter, microwaves of a frequency of 2.45 GHz and an output of 100 W were irradiated for 240 minutes to evaporate and remove the water. The temperature of the aqueous solution monotonously decreased after reaching a maximum at about 180 ° C. At the end of the microwave irradiation, the temperature of the composition in the container relative to the microwave irradiation time was about 150 ° C. After the completion of irradiation, it was cooled and depressurized with nitrogen gas to obtain a white solid. The obtained white solid was in the form of a lump in which a plurality of lithium iodide particles were integrated. The resulting white solid was recovered with a plastic spoon.

The mass (recovery amount) of the obtained white solid and the calculated recovery rate are shown in Table 1. The recovery rate was calculated by the following equation. Further, the water content of the obtained white solid was determined by the vaporization method (280 ° C.) of a Karl Fischer moisture measuring device, and the purity of lithium iodide was calculated from the measured value of iodide ion by an automatic titrator. The results are shown in Table 1.
Recovery rate = (mass of lithium iodide recovered) / (mass of lithium iodide input) x 100 (%)
Example 2

Place a container made of quartz glass containing 100.2 g of a colorless and transparent 55.6 mass% lithium iodide aqueous solution in a vacuum microwave dryer manufactured by Microelectronics Co., Ltd. Depressurized. Thereafter, microwaves of a frequency of 2.45 GHz and an output of 300 W were irradiated for 26 minutes, and then microwaves of an output of 100 W were irradiated for 84 minutes at the same frequency to evaporate and remove moisture. The temperature of the aqueous solution monotonously decreased after reaching a maximum at about 180 ° C. At the end of the microwave irradiation, the temperature of the composition in the container relative to the microwave irradiation time was about 140 ° C. After the completion of irradiation, it was cooled and depressurized with nitrogen gas to obtain a white solid. The obtained white solid was in the form of a lump in which a plurality of lithium iodide particles were integrated. The obtained white solid was recovered with a plastic spoon. The amount of recovery of the obtained white solid, recovery rate, water content, and LiI purity were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.
[Example 3]

Place a quartz glass container containing 300.5 g of a colorless and transparent 55.6% by mass aqueous solution of lithium iodide in a vacuum microwave dryer manufactured by Micro Electronics Co., Ltd. Depressurized. Thereafter, microwaves of a frequency of 2.45 GHz and an output of 800 W were irradiated for 20 minutes, and subsequently, microwaves of an output of 200 W were irradiated for 90 minutes at the same frequency to evaporate and remove water. The temperature of the aqueous solution monotonously decreased after reaching a maximum at about 170 ° C. At the end of the microwave irradiation, the temperature of the composition in the container relative to the microwave irradiation time was about 140 ° C. After the completion of irradiation, it was cooled, and the pressure was released by nitrogen gas to obtain a white solid. The obtained white solid was recovered with a plastic spoon. The obtained white solid was in the form of a lump in which a plurality of lithium iodide particles were integrated. The amount of recovery of the obtained white solid, recovery rate, water content, and LiI purity were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.
In addition, the obtained white solid is crushed to prepare a sample having an average particle diameter of about 15 mm, and the bulk density is measured by applying the bulk density measuring method of the granulated material of SAP01-79 planned by Japan Powder Technology Association. As a result, the bulk density was 0.54 g / cm ³ .

Comparative Example 1
In a 500 mL eggplant flask, 300.2 g of a colorless and transparent 55.6% by mass aqueous solution of lithium iodide was placed, and vacuum drying was performed by indirect heating using a rotary evaporator. As the conditions, after reducing the pressure to 2.5 kPa, drying was performed at a temperature of 200 ° C. for 6 hours. After completion of drying, the reaction solution was cooled, and depressurized by nitrogen gas to obtain a white solid. The obtained white solid was firmly fixed to the flask and could not be recovered with a plastic spoon, so it was recovered by breaking the flask with a mallet. The amount of recovery of the obtained white solid, recovery rate, water content, and LiI purity were measured and calculated in the same manner as in Example 1. The results are shown in Table 1.

  A substantially spherical sample having a diameter of about 15 mm was cut out from the lump obtained in Example 1, and the breaking strength was measured with a wooden house hardness tester 043019-A manufactured by Fujiwara Manufacturing Co., Ltd. The measurement was performed on 20 samples, and the mean value, standard deviation, t value and 95% confidence interval were calculated (significant level α = 0.05). The results are shown in Table 2.

  The anhydrous lithium iodide obtained in Comparative Example 1 was partially in the form of powder, but in the form of an aggregate fixed on the inner wall surface of the eggplant flask. A substantially spherical sample having a diameter of about 15 mm was cut out from the aggregate, and the breaking strength was measured with a wooden-house hardness meter 043019-E manufactured by Fujiwara Manufacturing Co., Ltd. The measurement was performed on 20 samples, and the average value of the breaking strength, the standard deviation, the t value and the 95% confidence interval were calculated (significant level α = 0.05). The results are shown in Table 2.

  The breaking strength of the lump obtained in Example 1 was about one tenth of the breaking strength of the aggregate of Comparative Example 1 obtained by drying by indirect heating.

  From the results of Examples 1 to 3, it is considered that in the heating by the microwave irradiation, the above-mentioned lump having a small breaking strength was obtained by the internal water boiling rapidly. As a result of obtaining such a lump, a high yield was obtained.

  In Examples 1 to 3, the reduction in the breaking strength makes it easy to recover lithium iodide even when it adheres to the wall surface, and the recovery rate is improved. Further, even when it is necessary to crush the obtained crystal mass, since the fracture strength is small, there is little possibility that the impurities are mixed due to abrasion or the like, and it is considered that high quality products can be stably produced.

Claims (6)

  A method for producing an inorganic iodine compound anhydride, comprising: a water removing step of evaporating water from the composition by irradiating the composition containing the inorganic iodine compound and water with microwaves under reduced pressure.   The method for producing an inorganic iodine compound anhydride according to claim 1, wherein the inorganic iodine compound is a compound in which a polymorphism including water of crystallization exists.   The manufacturing method of the inorganic iodine compound anhydride according to claim 1 or 2, wherein the composition is an aqueous solution of an inorganic iodine compound.   The manufacturing method of the inorganic iodine compound anhydride according to any one of claims 1 to 3, wherein the inorganic iodine compound is sodium iodide or lithium iodide.   The inorganic matter according to any one of claims 1 to 4, wherein the water removing step is performed until the temperature of the composition at least monotonously decreases with respect to the irradiation time when the microwave of constant output is irradiated. Method for producing iodine compound anhydride. It is a lump in which particles of a plurality of inorganic iodine compound anhydrides are integrated,
A lump having a breaking strength of 100 N or less.

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