JPH06305717A - Method for dehydrating concrete body of sodium sulfide with inert gas - Google Patents

Abstract

PURPOSE:To provide a method for dehydrating a concrete body of sodium sulfide by which a high concn. concrete sodium sulfide body can be obtd. in a short time in a high yield without degenerating the sodium sulfide. CONSTITUTION:When a concrete body of sodium sulfide having >=55wt.% total sodium sulfide content is dehydrated, the temp. of the sodium sulfide body is slowly raised to >=95 deg.C while allowing inert gas to flow to the body and then the temp. is rapidly raised to dehydrate the body under ventilation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to flakes, chips, pellets, etc. of sodium sulfide, and a product obtained by crushing a cooled and solidified solution of an aqueous solution to the same extent as the above-mentioned molded product. The present invention relates to a method for dehydrating sodium sulfide tangible substances.

[0002]

2. Description of the Related Art Conventionally, sodium sulfide has been prepared by reacting an aqueous solution having a sodium hydrosulfide content of about 72% with an aqueous solution having a caustic soda content of about 75% by weight in an equimolar manner to form an aqueous solution having a sodium sulfide content of about 60% by weight, and then using a flaker. Flake-shaped over.
As a method for producing the anhydride, there is a method of heating and dehydrating under reduced pressure. However, if the pressure or temperature is too high, melting occurs, so that the apparatus is significantly corroded and it is difficult to take it out.

As a method of dehydrating while preventing melting,
A method is known in which the temperature is raised to 810 ° C. over a long period of time under a reduced pressure of 1 Torr to dehydrate (US Pat. No. 253316).
No. 3 specification). However, such a high temperature is not practical. In addition, about 60 wt% sodium sulfide aqueous solution
The method of precipitating anhydrous crystals at 0 ° C. or higher (see JP-A-64-28207) has a high concentration of sodium sulfide and causes significant apparatus corrosion from around 100 ° C., thus avoiding inclusion of impurities. Can not.

A method of preventing melting and dehydrating while maintaining the crystal system (JP-A-2-51404 and JP-A-2-51)
No. 406) dehydrates in two steps, and since it is necessary to delicately control the temperature and pressure during dehydration, it is extremely complicated and there is a problem that dehydration requires a long time. there were. Further, a method of adding a low hydrate or an anhydride to a high hydrate and drying the mixture under reduced pressure (see JP-A-4-310508) dehydrates only the water content of the low hydrate to be added. In addition, since the drying temperature under reduced pressure needs to be kept below the melting point of the hydrate, there is a problem that it takes a long time to dry.

Therefore, the present inventors have added a method of adding low-moisture sodium sulfide powder for heating and dehydration in order to prevent the melting and adhesion of the sodium sulfide tangible material (see Japanese Patent Application No. 5-33160), and A method of dehydrating the surface of a tangible substance of sodium hydrosulfide while flowing an inert gas to form a whitening film, and then dehydrating by heating under reduced pressure (see Japanese Patent Application No. 5)
Was proposed first.

[0006]

However, the former method requires a step of sieving the powder from the tangible substance after dehydration, and the powder to be added is obtained by pulverizing the dehydrated tangible substance. Since it is used, the production efficiency is reduced, and there is a possibility that powder that is deteriorated due to contact with air during the crushing operation may be mixed into the product.

Further, in the latter method, when the whitening film is formed on the surface of the tangible substance of sodium sulfide, the process shifts to depressurization heating dehydration, so that the thickness of the whitening film is not sufficient, and the temperature rise of depressurization heating dehydration is high. If the speed is too fast, there is a concern that tangible material may melt, and it was necessary to keep the temperature rising rate low. Therefore,
The present invention solves the drawbacks of the latter method and provides a method for dehydrating a tangible substance of sodium sulfide that enables dehydration after formation of a whitening film to be performed at a rapid temperature rise.

[0008]

The present invention provides (1) a method of dehydrating a sodium sulfide tangible material containing 55% by weight or more of the total sodium sulfide content while flowing an inert gas into the sodium sulfide tangible material. A method of dehydrating sodium sulfide tangible, characterized by gradually raising the temperature of the tangible substance to 95 ° C or higher, and then rapidly raising the temperature to perform dehydration by aeration, (2) plus the melting point of the raw material sodium sulfide. An inert gas heated to a temperature of 12 ° C. or lower is caused to flow at a flow rate of 3 normal liters per minute or more per 100 g of the raw material to start dehydration of a tangible substance, and the melting point of sodium sulfide as a raw material plus a temperature rise from 12 ° C. The sodium sulfide tangible product according to (1) above, wherein the speed is controlled to 0.1 ° C. or less per minute and the temperature of the tangible product is 95 ° C. or more, and then the temperature is rapidly raised to perform dehydration by aeration. Dehydration method, and (3)
Dehydration of tangible material by heating the container containing the raw material of sodium sulfide to a temperature not higher than the melting point of the raw material of sodium sulfide plus 12 ° C. while flowing an inert gas at a flow rate of 3 normal liters per minute or more per 100 g of the raw material of sodium sulfide. And the rate of temperature rise from the melting point of the raw material sodium sulfide plus 12 ° C to 0.1 per minute.
After the temperature of the tangible object reaches 95 ℃ or higher,
The above (1) characterized by rapidly heating and aeration dehydration
It is a method for dehydrating the described sodium sulfide tangible material.

In the present invention, the tangible substance of sodium sulfide refers to flakes, chips, pellets, and pulverized substances having a diameter of about 3 to 10 mm obtained by pulverizing a cooled solidified product of an aqueous solution. Further, examples of the inert gas used in the present invention include gases such as hydrogen, nitrogen, and argon that are inert to sodium hydrosulfide. The present invention has a total sodium sulfide content of 4
It is effective for dehydrating 5 wt% or more of sodium sulfide tangible material. If the total sodium sulfide content is less than 45% by weight, it may melt during the dehydration process and adhere to the container, reducing the dehydration efficiency.

[0010]

The present inventors, while examining various methods of heating and dehydrating by passing an inert gas, heat and dehydrate a tangible substance to 95 ° C. or more, and then melt the tangible substance even if the temperature is rapidly raised. The present invention has been completed by discovering that heating aeration dehydration can be carried out without heating. That is, the sodium sulfide tangible substance is heated by heating the inert gas and / or raw material container to a temperature not higher than the melting point of the tangible substance raw material plus 12 ° C. to start aeration dehydration, and the inert gas and / or raw material sodium sulfide of the raw material container When the temperature of the tangible substance is dehydrated to 95 ° C. or higher while adjusting the temperature rising rate from the melting point plus 12 ° C. to 0.1 ° C. or less per minute, the subsequent aerated dehydration by rapid temperature increase becomes possible. In particular, in the rapid temperature rise dehydration step, it is possible to perform aeration dehydration without worrying about melting of tangible substances and without requiring accurate temperature rise control.

After heating the tangible substance to 95 ° C. or higher, it is possible to dehydrate it while maintaining the temperature of the inert gas and / or the raw material container at that time, but it takes a long time for dehydration, which is suitable. Not. In the above aeration dehydration, the inert gas needs to be aerated at 3 normal liters per minute or more per 100 g of the sodium sulfide tangible material, and preferably 4 to 30 normal liters. If it is less than 3 normal liters per minute per 100 g of the raw material, the anti-melting effect may be lowered and the material may be melted, and the processing time becomes long, which is not suitable.

If the temperature of the inert gas at the start of aeration dehydration or the temperature of the raw material container exceeds the melting point of the sodium sulfide tangible material raw material plus 12 ° C., the tangible material may be melted. Further, in the process of raising the temperature of the inert gas or the raw material container, if the temperature difference between the temperature of the tangible substance and the temperature of the inert gas or the raw material container becomes large, part of the tangible substance may melt, In the above process, it is preferable to keep the inert gas or the raw material container in a relatively low temperature state at a temperature of 35 ° C. or higher, particularly 40 ° C. or higher. When the temperature of the tangible substance of sodium sulfide exceeds 95 ° C, it is possible to rapidly raise the temperature for dehydration by heating, but dehydration over 200 ° C is not practical, and the economical temperature is 150 ° C or lower. The total processing time is 20
0 to 400 minutes is preferable.

It is necessary to use an inert gas having a relative humidity (hereinafter referred to as water) of 50% or less. 5
If it exceeds 0%, the processing time becomes long, which is not preferable. In the present invention, since the sodium sulfide tangible material is treated in the inert gas flow, the sodium sulfide does not come into contact with air to be deteriorated.

[0014]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto. (Example 1) Commercial flaky sodium sulfide (about 1-2 c)
a thickness of about 1.5mm m ^2, and the total sodium sulfide content 60.3 wt%, the melting point 83 ° C.) 200 g, placed in a rotary evaporator a 500 milliliter, 44 ° C. from its bottom
Nitrogen gas was aerated at a rate of 10 normal liters per minute, the contents were immersed in a constant temperature bath at 95 ° C with stirring to start dehydration, and the temperature of the constant temperature bath was raised to 117 ° C over 240 minutes. The temperature of the contents was 96 ° C. Then, the temperature of the constant temperature bath was raised to 130 ° C. over 15 minutes, and the temperature was maintained for 60 minutes for dehydration. The obtained flaky sodium sulfide was 115 g (recovery rate 94%), and its composition was such that the total sodium sulfide content was 99.0% by weight and the water content was 0.2% by weight.

(Example 2) 200 g of the commercially available flaky sodium sulfide used in Example 1 was put in a 500 ml rotary evaporator, and 95 ° C. was applied from the bottom thereof.
Nitrogen gas was aerated at a rate of 10 normal liters per minute, the contents were immersed in a constant temperature bath at 60 ° C with stirring to start dehydration, and then the gas temperature was changed to 110 ° C over 170 minutes.
The temperature of the contents was raised to 96 ° C. Then, the gas temperature was raised to 140 ° C. over 90 minutes to obtain 114 g of dehydrated flaky sodium sulfide (collection rate 94%). The composition of the obtained sodium sulfide was 99.1% by weight of total sodium sulfide and 0.2% by weight of water.

(Example 3) The same as Example 1 except that the supply amount of nitrogen gas was changed to 7 normal liters per minute (corresponding to 3.5 normal liters per 100 g of the raw material). When the flaky sodium sulfide tangible substance was dehydrated, the total amount of sodium sulfide was 98.6% by weight and the water content was 0.5% by weight.
It was possible to recover 4 g, and the recovery rate was 93%.

Example 4 200 g of a sodium sulfide pulverized product (total sodium sulfide content 56.1% by weight, melting point 79 ° C.) obtained by cooling and solidifying an aqueous solution of sodium sulfide to a size of 3 to 8 mm was used.
Put in a 00 ml rotary evaporator,
Nitrogen gas at 70 ° C. is aerated from the bottom at a rate of 10 normal liters per minute, and the contents are immersed in a 90 ° C. constant temperature tank to start dehydration, and then the temperature of the constant temperature tank is set to 2
The temperature of the contents is raised to 95 by heating to 113 ° C over 50 minutes.
℃. Then, the temperature of the constant temperature bath is kept at 130 for 25 minutes.
The temperature was raised to 0 ° C., and the temperature was maintained for 90 minutes for dehydration.
The obtained flaky sodium sulfide was 106 g (recovery rate 9
3%), and the composition was 98.8% by weight of total sodium sulfide and 0.1% by weight of water.

Comparative Example 1 Example 1 was repeated except that the temperature of the constant temperature bath at the start of aeration and dehydration was changed from 95 ° C. to 105 ° C. (a temperature 22 ° C. higher than the melting point 83 ° C. of the raw material flakes). When the flaky sodium sulfide tangible material was dehydrated in the same manner as above, a part of the tangible material began to melt 9 minutes after aeration with nitrogen gas.

(Comparative Example 2) In Example 1, the temperature of the constant temperature bath at the start of the aeration and dehydration was set to 95 ° C, and then the aeration and dehydration was performed at a temperature rising rate of the container of 0.4 ° C / min. ,
After 51 minutes, part of the tangible material began to melt.

(Comparative Example 3) In Example 1, the temperature of the thermostat at the start of aeration and dehydration was set to 95 ° C, and then the temperature of the thermostat was raised to 102 ° C over 80 minutes to change the temperature of the contents. It was set to 85 ° C. Then, when the gas temperature was raised to 0.5 ° C. per minute, a part of the tangible material began to melt after 30 minutes.

Comparative Example 4 The same as Example 1 except that the supply amount of nitrogen gas was changed to 4 normal liters per minute (corresponding to 2 normal liters per minute per 100 g of the raw material). When dehydration of the flaky sodium sulfide tangible substance was started, melting started 54 minutes later.

[0022]

EFFECTS OF THE INVENTION By adopting the above construction, the present invention makes it possible to obtain a high concentration of sodium sulfide tangible substance in a high yield in a short time without deteriorating sodium sulfide. In particular, by setting the temperature of the contents to 95 ° C. or higher, the subsequent dehydration can be performed at a rapid temperature rise. Further, such high-concentration sodium sulfide makes it possible to use it in fields where moisture is disliked, particularly in organic chemical reactions, and greatly contributes to expansion of the range of use.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroaki Eda 432 Kase, Mitsu-cho, Otsu-gun, Okayama (72) Inventor Shingo Imai 1-15-10 Tambara, Tamano-shi, Okayama

Claims (3)

[Claims] 1. A method for dehydrating a sodium sulfide tangible material containing 55% by weight or more of total sodium sulfide until the temperature of the tangible material reaches 95 ° C. or more while flowing an inert gas through the sodium sulfide tangible material. A method of dehydrating a tangible substance of sodium sulfide, which comprises gradually increasing the temperature and then rapidly increasing the temperature to perform dehydration by aeration. 2. The dehydration of tangible substances is started by flowing an inert gas heated to a melting point of sodium sulfide as a raw material plus 12 ° C. or less at a flow rate of 3 normal liters per minute or more per 100 g of the raw material to start dehydration of tangible substances. Melting point of sodium sulfide + 12 ℃
2. A sodium sulfide soda according to claim 1, wherein the temperature rising rate is controlled to 0.1 ° C. or less per minute, and after the temperature of the tangible substance reaches 95 ° C. or higher, the temperature is rapidly raised to perform aeration dehydration. Method for dehydrating tangible substances. 3. A container containing the raw material sodium sulfide is heated to a temperature not higher than the melting point of the raw material sodium sulfide plus 12 ° C. while flowing an inert gas at a flow rate of 3 normal liters per minute or more per 100 g of the sodium sulfide tangible material raw material. To start dehydration of the tangible substance, suppress the rate of temperature rise from the melting point of the raw material sodium sulfide plus 12 ° C to 0.1 ° C or less per minute, and rapidly raise the temperature of the tangible substance to 95 ° C or more. The method for dehydrating tangible material of sodium sulfide according to claim 1, wherein the method is dehydrated by aeration with heating.