JPS62124240A - Manufacture of metallic re - Google Patents

Abstract

PURPOSE:To obtain high-grade rhenium in high efficiency by reducing potassium perrhenate in three stages at prescribed temp. and by subjecting the above to dehydration treatment and drying under prescribe conditions. CONSTITUTION:The potassium perrhenate is subjected to the first reduction at 250-350 deg.C, to the second reduction at 650-750 deg.C, and finally to the third reduction at >=950 deg.C. The resulting reduced substance is washed with water until pH of 6.8-7.5 is reached. The above is dehydrated and then dried at <=200 deg.C.

Description

[Detailed description of the invention] Completed 1L reason! one The present invention relates to a method for producing metal Re.

The method for obtaining metal Re is either by reducing potassium perrhenate with hydrogen, or by converting potassium perrhenate into rhenium (IV) sulfide and then converting it to ammonium perrhenate. Methods are being considered in which the amount is recovered after the amount is recovered.

However, there is no disclosure of how to perform the reduction in a manner that completely reduces volatilization loss and does not cause melting or the like during operation.

As a result of intensive study, the inventors made the following invention.

The present invention is as follows: (1) A method for producing metal Re, which involves reducing potassium perrhenate, leaching it with water, dehydrating it, and then drying it.

(2) The method for producing metal Re according to (1), in which the first stage reduction is carried out at 250 to 350°C, the second stage reduction is carried out at 650 to 750°C, and then the third stage reduction is carried out at 950°C or higher.

(3) The method for producing metal Re according to (1), wherein the drying temperature is 200° C. or lower.

(4) The method for producing metal Re according to (1), in which washing with water during filtration is carried out until the pH becomes 6.8 to 7.5.

When reducing potassium perrhenate, it is preferable to remove oxygen from the furnace before the reduction temperature is reached.

For example, a gas that does not contain oxygen up to about 200 to 350 degrees Celsius,
For example, it is preferable to replace the gas with nitrogen gas, inert gas, or the like.

Thereafter, it is preferable to perform reduction by blowing in a reducing gas. It is preferable that the reduction is carried out in three stages as described below. The reduction temperature at low temperatures is 250-350°C. The retention time for reduction is preferably about 30 minutes to 1 hour and 30 minutes. Hydrogen or the like is used as the reducing gas in this case.

The reason why rhenium oxide is kept at a low temperature is that depending on its form, rhenium oxide is thought to volatilize at extremely low temperatures, which in turn deteriorates the recovery rate.

After reduction at low temperature, hold at medium temperature. This is KRe
This is because it is preferable to sufficiently reduce the temperature below the melting temperature of O4.

The second stage reduction temperature is preferably 650 to 750°C.

This is because at temperatures below 650° C., reduction is not sufficiently performed, and at temperatures above 750° C., KReO4 begins to melt.

After reduction at the above temperature, the melting point increases, so even if the third stage of reduction is performed thereafter, the material will not melt.

The reduction temperature in the third stage is preferably 950°C or higher.

This is to reduce things that can be reduced at high temperatures.

This is because there is rhenium oxide that is reduced at the product temperature.
The holding time at medium and high temperatures is also preferably 30 minutes to 1 hour and 30 minutes.

Further, as the reducing gas, for example, hydrogen gas or the like is used.

After the reduction treatment at high temperature, it is preferable to replace the inside of the furnace with nitrogen gas or other oxygen-free gas to cool the furnace.

This is to prevent re-oxidation and to perform reduction treatment at low cost.

The obtained reduced product is leached with water, dehydrated, and then dried.

When leaching with water, it is preferable to wash with water until the pH reaches 6.8 to 7.5, in order to completely wash and remove the liquid.

Dehydration treatment is obtained by filtration or the like. The dehydrated material is then dried. The drying temperature is preferably 200°C or lower.

This is to prevent oxidation and volatilization loss of Re.

By implementing the present invention as described in Section 2, the following effects can be obtained.

(1) High-grade rhenium with a Re grade of 99% or higher can be obtained.

(2) K can also be removed to 0.1% or less.

(3) Three-stage reduction enables stable operation and high Re recovery rate.

Example 1 Potassium perrhenate was placed in a reduction furnace, and while the temperature was rising to 250°C, the inside of the furnace was replaced with nitrogen gas, and then N2 gas, which is a reducing gas, was blown in and held at 300°C for 60 minutes. . After that, the temperature was raised to 700°C and held for 60 minutes, and then heated to 100°C.
Reduction treatment was performed by holding at 0°C for 60 minutes.

Thereafter, the furnace was cooled while replacing the inside of the furnace with N2 gas.

After cooling the furnace, water leaching K was removed and washing was performed until the pH reached 7.

After washing, drying was performed at 150°C.

Through the above treatment, the recovery rate of rhenium was 100%, the reduction rate was also 100%, and the grade of K was 0.1% or less, so that high-quality Re was obtained.

Comparative Example 1 When the first stage reduction temperature was set to 400° C. and other conditions were kept the same, the recovery rate of Re was 98%, which was not a preferable value.

Comparative Example 2 When the second stage treatment temperature was not maintained and other conditions were kept the same, KHCO3 melted at 1000° C., making reduction treatment impossible.

Comparative Example 3 When the drying temperature was 300°C and the other conditions were the same,
The Re recovery rate showed a poor value of 97%.

Claims (4)

[Claims] (1) A method for producing metal Re, which comprises reducing potassium perrhenate, leaching it with water, dehydrating it, and then drying it. (2) In the reduction, the first stage reduction is carried out at 250 to 350°C, the second stage reduction is carried out at 650 to 750°C, and then the third stage reduction is carried out at 950°C or higher. 2. Method for producing metal Re as described in Section 1. (3) The method for producing metal Re according to claim 1, wherein the drying temperature is 200° C. or lower. (4) The method for producing metal Re according to claim 1, characterized in that washing with water during filtration is performed until the pH reaches 6.8 to 7.5.