Process for the production of ammonium perrhenate

Abstract

The present invention relates to a process for the production of ammonium perrhenate (APR), which includes the use of Ca(OH)2 and to ammonium perrhenate which can be obtained by the method according to the invention.

Claims

1. Process for the production of ammonium perrhenate, comprising the following steps: a) providing an aqueous suspension comprising rhenium-containing compounds; b) adding Ca(OH).sub.2 to the suspension from step a), the pH value being greater than 7; c) adding an oxidizing agent to the aqueous suspension from step b), the temperature of the suspension not exceeding 50 C.; d) heating the suspension from step c) to at least 95 C. and subsequent filtration, the suspension being cooled to 60 C. or less prior to filtration; e) adding an ammonium carbonate to the filtrate from step d) to obtain an aqueous suspension containing ammonium perrhenate; f) filtering the suspension from step e); g) reducing the amount of liquid of the filtrate from step f) to obtain solid ammonium perrhenate.

2. Process according to claim 1, characterized in that the rhenium-containing compounds are obtained from rhenium-containing by-products.

3. Process according to claim 1, characterized in that the aqueous suspension in step a) is produced by treating the rhenium-containing compounds in water in the presence of acid.

4. Process according to claim 1, characterized in that the rhenium-containing compounds are selected from the group consisting of ReS.sub.2, Re.sub.2S.sub.7, and ReO.sub.2.

5. Process according to claim 1, characterized in that the oxidizing agent in step c) is selected from the group consisting of hydrogen peroxide, chlorates, perchlorates, and mixtures thereof.

6. Process according to claim 1, characterized in that the ammonium carbonate is selected from ammonium carbonate or ammonium hydrogen carbonate.

7. Process according to claim 1, characterized in that the suspension from step e) is heated to a temperature in the range of 60 C. to 70 C.

8. Process according to claim 1, characterized in that the ammonium perrhenate is subjected to further purification steps.

9. Process according to claim 1, characterized in that the ammonium perrhenate is further converted to rhenium metal.

Description

EXAMPLES

Example 1

(1) Ammonium perrhenate was produced from a rhenium-containing compound in accordance with the inventive process of the present invention.

(2) 400 kg rhenium sulphide is suspended in 4 m3 of water, and then 400 kg Ca(OH)2 is added so that a pH value above 7 is obtained. Subsequently, 400 liters of hydrogen peroxide (30% aqueous solution) are added at a temperature of about 40 C. After oxidation, the suspension is heated to 95 C. and kept at this temperature for 12 hours.

(3) The suspension is then cooled to 60 C. and supplied by a pump to a filter press and is filtered.

(4) The filtrate is kept at 60 C. and ammonium hydrogen carbonate is added to form ammonium perrhenate. The suspension thus obtained is then filtered at 50 C. in a filter press. The filtrate is then dried under reduced atmospheric pressure.

(5) The analysis of the ammonium perrhenate obtained revealed a rhenium content of 67.09% by weight.

Comparative Test

(6) According to the prior art, a rhenium sulfide concentrate (Re2S7) was dissolved under alkaline conditions with NaOH and H2O2 and was then obtained by an ion exchanger as well as subsequent recovery of the rhenium by evaporation.

(7) The rhenium content of the process known according to the prior art resulted in a value of 58.55% by weight.

(8) The process according to the invention also leads to products with a low water content.