JP3561281B2 - Dehydration method of tangible sodium hydrosulfide with inert gas - Google Patents

Description

[0001]
[Industrial applications]
The present invention is a molded product such as flakes, chips, and pellets of sodium hydrogen sulfide, and a solidified product obtained by cooling and solidifying an aqueous solution to the same degree as the molded product, such as a sodium sulfide tangible material having a certain size or more. To a method of dehydrating.
[0002]
[Prior art]
Commercially available sodium hydrogen sulfide is obtained by heating and concentrating an aqueous solution having a total sodium sulfide content of about 25 to 45% to a total sodium sulfide content of about 70% by weight. It is put and cooled and solidified.
This sodium bisulfide contains a little more than 25% of water, which hinders its use in reactions that dislike water, especially reactions with organic substances.
[0003]
On the other hand, when producing high-concentration sodium hydrogen sulfide by dehydration and concentration, the viscosity of the liquid sharply increases from a concentration of about 75% by weight, and it becomes impossible to transfer the liquid with a normal pump. As a result, the dehydration efficiency is significantly reduced.
Under these circumstances, 70 to 75% by weight of sodium hydrosulfide is commercially available.
[0004]
Therefore, the present inventors devised a first method of heating and dehydrating the surface of a tangible material at a temperature of 60 ° C. or less under reduced pressure, as a method of heating and dehydrating the tangible sodium hydrosulfide under reduced pressure. (See Japanese Patent Application No. 5-41265), a second method of adding a low-moisture sodium bisulfide powder and heating and dehydrating to prevent the molten sodium sulfide tangible material from adhering to the melt (Japanese Patent Application No. 5-41267). See above).
[0005]
[Problems to be solved by the invention]
However, the first method requires strict temperature control in the preliminary dehydration under reduced pressure, and requires a long time for the dehydration treatment. The transformation of soda cannot be avoided.
Further, in the second method, a step of sieving the powder from the tangible material after dehydration is required, and the powder to be added is used by pulverizing the dehydrated tangible material, which leads to a decrease in production efficiency. At the same time, there is a risk that powder that has been altered by contact with air during the pulverization operation may be mixed into the product.
Therefore, the present invention is intended to solve the above-mentioned drawbacks and to provide a method for simply and effectively dehydrating a soda hydrosulfide tangible material.
[0006]
[Means for Solving the Problems]
The present invention provides (1) a method for dehydrating a sodium hydrogen sulfide tangible material containing 65% by weight or more of total sodium hydrogen sulfide, wherein the sodium hydrosulfide tangible material is heated to a temperature equal to or lower than the melting point of the raw material sodium hydrogen sulfide plus 5 ° C or less. Dehydration is started by flowing the heated inert gas at a flow rate of 2 normal liters or more per minute per 100 g of the raw material, and then, when raising the temperature of the inert gas from the melting point of the raw material sodium hydrogen sulfide plus 5 ° C, Sodium hydrogen sulfide, characterized in that the rate of temperature rise is kept at 0.1 ° C. or less per minute , the temperature of the tangible material is gradually raised until it reaches 57 ° C. or more, and then the temperature is rapidly raised to aeration and dehydration. A method for dehydrating a tangible material, and (2) a method for dehydrating a tangible sodium bisulfide material containing 65% by weight or more of total sodium hydrosulfide content, wherein the sodium bisulfide tangible material is converted to a sodium hydrosulfide tangible material per 100 g per minute. 2 normal liters or less While flowing the inert gas at the above flow rate, the container containing the raw material is heated to a temperature not higher than the melting point of the raw material sodium hydrogen sulfide plus 5 ° C. to start dehydration, and then the melting point of the raw material sodium bisulfide plus Upon 5 ° C. for raising the temperature of the raw material container than, kept below min 0.1 ° C. the rate of temperature increase, the temperature was gradually raised to a temperature of the material object is equal to or greater than 57 ° C., then rapidly heated a dehydrating method of sodium hydrosulfide material objects you characterized bubbling dehydration by.
[0007]
In the present invention, the tangible sodium hydrosulfide refers to flakes, chips, pellets, and a pulverized product having a diameter of about 3 to 10 mm obtained by pulverizing a cooled solidified aqueous solution. Examples of the inert gas used in the present invention include hydrogen, nitrogen, argon, and other gases that are inactive against sodium bisulfide.
INDUSTRIAL APPLICABILITY The present invention is effective for dewatering tangible sodium hydrosulfide having a total sodium hydrosulfide content of 65% by weight or more. If the total sodium hydrosulfide content is less than 65% by weight, it melts in the process of dehydration and adheres to the container, which may reduce the dehydration efficiency.
[0008]
[Action]
The present inventors have studied various methods of heating and dehydrating by passing an inert gas, and after heating and dehydrating the tangible material to 57 ° C. or more, the tangible material may be melted even if the temperature is rapidly increased. In addition, the inventors have found that heating, ventilation, and dehydration can be performed, and have completed the present invention.
That is, the soda hydrosulfide tangible material starts dehydration by heating the inert gas and / or the raw material container to a temperature equal to or lower than the melting point of the tangible material raw material plus 5 ° C., and increases the temperature rising rate of the inert gas and / or the raw material container. While dehydrating until the temperature of the tangible material reaches 57 ° C. while adjusting the temperature to 0.1 ° C. per minute or less, preferably in the range of 0.04 to 0.07 ° C., aeration dehydration by rapid temperature rise is possible thereafter. . In particular, in the rapid temperature rising dehydration step, the ventilation dehydration can be performed without worrying about melting of the tangible material and without requiring precise temperature rising control.
[0009]
In addition, after the tangible material is heated to 57 ° C. or higher, it is possible to perform dehydration while maintaining the temperature of the inert gas and the raw material container at that time, but it is industrially effective because dehydration requires a long time. Not.
In the above-mentioned aeration dehydration, the inert gas needs to be aerated at a rate of 2 normal liters per minute or more per 100 g of the raw material of sodium sulfide material, preferably 4 to 30 normal liters per minute.
[0010]
If the temperature of the inert gas at the start of aeration and dehydration and the temperature of the raw material container exceed the melting point of the raw material of sodium hydrosulfide tangible material plus 5 ° C., the tangible material may be melted, and the flow rate of the inert gas per minute If the amount is less than 2 normal liters, the effect of preventing melting is reduced, and there is a possibility of melting.
Further, when the temperature of the sodium hydrogen sulfide tangible exceeds 57 ° C., the temperature can be raised rapidly to perform dehydration by heating. However, dehydration exceeding 170 ° C. is not practical, and the economical temperature is 150 ° C. or lower. is there.
The total processing time is preferably from 250 to 400 minutes.
[0011]
Further, it is necessary to use an inert gas having a relative humidity (hereinafter, referred to as moisture) of 50% or less. If it exceeds 50%, the processing time is undesirably long.
In the present invention, since the tangible sodium hydrosulfide is treated in the inert gas stream, the sodium hydrosulfide does not deteriorate in contact with air.
[0012]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto .
[0013]
(Example 1 )
200 g of commercially available flaked sodium hydrosulfide (about 1-2 cm ² , about 1.5 mm thick, 72.4% by weight of total sodium hydrosulfide, melting point 52 ° C.) was placed in a 500 ml rotary evaporator, Nitrogen gas is introduced at a rate of 8 normal liters per minute, the contents are immersed in a constant temperature bath at 56 ° C. with stirring to start dehydration, and the temperature of the constant temperature bath is raised to 73 ° C. over 300 minutes. The material temperature was 57 ° C. Thereafter, the temperature of the thermostat was raised to 110 ° C. over 60 minutes, and the temperature was maintained for 30 minutes to perform dehydration.
The obtained flaked sodium hydrogen sulfide was 137 g (recovery rate 93%), and its composition was 98.3% by weight of total sodium hydrosulfide and 0.3% by weight of water.
[0014]
(Example 2 )
In Example 1 , the flaked sodium sulfide tangible material was dehydrated in the same manner as in Example 1 except that the supply amount of nitrogen gas was changed to 5 normal liters per minute. 136 g of flaky sodium hydrogen sulfide having 1% by weight and 0.5% by weight of water could be recovered, and the recovery rate was 92%.
[0015]
(Example 3 )
In Example 1 , instead of the flaked sodium hydrosulfide, an aqueous solution of sodium hydrosulfide was cooled and solidified, and ground to a size of 3 to 8 mm (66.9% by weight of total sodium hydrosulfide, melting point 49 ° C). 200 g) was placed in a 500 ml rotary evaporator, and the contents were immersed in a constant temperature bath at 52 ° C. with stirring, and nitrogen gas heated to 45 ° C. was started to be ventilated at a rate of 12 normal liters per minute, and then heated at a constant temperature. The temperature of the vessel was raised to 65 ° C over 250 minutes to bring the temperature of the contents to 58 ° C.
Thereafter, the temperature of the constant temperature bath was raised to 120 ° C. over 100 minutes, and the temperature was maintained for 50 minutes to perform dehydration. The total sodium hydrosulfide content was 98.4% by weight and the water content was 0.2% by weight. 127 g of ground sodium hydrogen sulfide could be recovered, and the recovery rate was 93%.
[0016]
(Comparative Example 1)
In Example 1 , after the start of the aeration and dehydration, the temperature of the thermostat was raised from 56 ° C. to 62 ° C. over 90 minutes, and the temperature of the contents was set to 46 ° C. Thereafter, when the temperature of the thermostatic bath was rapidly increased at a rate of 0.5 ° C./min, melting started in 15 minutes after the subsequent rapid temperature increase was started.
[0017]
(Comparative Example 2)
In Example 1, except that the temperature of the thermostat at the start of the ventilation dehydration was changed from 56 ° C. to 60 ° C., dehydration of the flaky sodium hydrosulfide tangible material was performed in the same manner as in Example 1. Twelve minutes later melting began.
[0018]
(Comparative Example 3)
In Example 1, when the temperature of the thermostatic bath was raised at 0.5 ° C./min after the start of the ventilation dehydration, the melting started 15 minutes after the start of the ventilation dehydration.
[0019]
(Comparative Example 4)
In Example 1 , the flake-like sodium hydrosulfide tangible was dehydrated in the same manner as in Example 1 except that the nitrogen gas flow rate was changed to 3 normal liters per minute. Melting has begun.
[0020]
【The invention's effect】
ADVANTAGE OF THE INVENTION By adopting the said structure, this invention became able to obtain the high concentration sodium sulfide tangible material with high yield in a short time, without denaturing sodium bisulfide. In particular, after the temperature of the contents was raised to 57 ° C. or higher, dehydration could be performed under rapid temperature rise, and the temperature rise control became extremely simple. Such high-concentration sodium bisulfide enables use in fields that dislike moisture, especially in organic chemical reactions, and greatly contributes to expansion of the range of use.

Claims (2)

In a method for dehydrating a sodium hydrogen sulfide material containing 65% by weight or more of total sodium hydrogen sulfide , an inert gas heated to a temperature not higher than the melting point of the raw material sodium hydrogen sulfide plus 5 ° C is added to the sodium hydrogen sulfide material. Then, dehydration is started by flowing at a flow rate of 2 normal liters or more per minute per 100 g of the raw material, and then, when the temperature of the inert gas is raised from the melting point of the raw material sodium bisulfide plus 5 ° C., the heating rate is set to 0 / min. 1. A method for dehydrating sodium sulfide tangible material, wherein the temperature is controlled to 1 ° C. or less, the temperature of the tangible material is gradually increased until the temperature becomes 57 ° C. or higher, and then the temperature is rapidly increased to carry out aeration dehydration. A method for dehydrating a sodium hydrogen sulfide material containing 65% by weight or more of total sodium hydrogen sulfide, wherein an inert gas is supplied to the sodium hydrogen sulfide material at a flow rate of at least 2 normal liters per minute per 100 g of the sodium hydrogen sulfide material material. While flowing, the container containing the raw material is heated to a temperature equal to or lower than the melting point of the raw material sodium hydrosulfide plus 5 ° C. to start dehydration, and then the temperature of the raw material container is raised from the melting point of the raw material sodium bisulfide plus 5 ° C. Upon raising the temperature, kept below min 0.1 ° C. the rate of temperature increase, characterized in that the temperature of the tangible object is gradually heated until the above 57 ° C., vented dried then rapidly heated dehydration process of be that sodium hydrosulfide tangible products and.