Recycling of superalloys with the aid of an alkali metal salt bath

A process for obtaining rhenium from a superalloy consisting of the following steps:

• a) digesting the superalloy in a salt melt consisting essentially of 60-95% by weight of NaOH and 5-40% by weight of Na2SO4,
• b) cooling of the melt to room temperature,
• c) commination of the melt digestion product,
• d) reacting of the comminuted melt digestion product in water at temperatures of less than 80° C. and production of an aqueous suspension containing
• a solution consisting of a mixture of sodium compounds from the group consisting of NaOH, Na2SO4, NaAl(OH)4 and/or Na2CO3 and alkali metallates of the elements of the 6th and/or 7th subgroup of the Periodic Table of the Elements;
• a solid metallic phase consisting of the group of metals Co, Ni, Fe, Mn and Cr;
• a solid phase consisting of hydroxides and/or hydrated oxides of the metals of the 3rd main group and of metals of the 4th and/or 5th subgroup of the Periodic Table of the Elements,
• e) removing of the aqueous fraction by filtration, and
• f) removing of the rhenium from the aqueous fraction.