Method and apparatus for reconditioning waste solutions of the nuclear industry which contain ammonium nitrate

摘要

A method and apparatus for reconditioning waste solutions of the nuclear industry which contain ammonium nitrate. The waste solution is continuously sprayed from above into a 300 to 600 C. hot zone, from the lower end of which the decomposition products are withdrawn and are separated into condensate and exhaust gas. The NO content is reduced by adding oxygen, especially at the exit of the decomposition zone. By the presence of reducing agents, such as CO(NH.sub. 2).sub.2 or preferably NH.sub.3, in the solution to be sprayed, the NO. sub.2 content of the decomposition products and the NH.sub.4 NO.sub.3 residue in the condensate can be practically eliminated and an additional precipitation in the condensate which can be filtered off can be obtained. Optimal contents are 0.25-0.4 Mol NH.sub.3 and 0.15-0.25 Mol CO(NH.sub.2) .sub.2 per Mol NH.sub.4 NO.sub.3. Prior to the thermal decomposition, the waste solution is preferably concentrated, cooled off, and filtered to about 60% or (if a solution containing reducing agents is to be sprayed) about 48% NH.sub.4 NO.sub.3 at about 60 C. in a thin layer evaporator, and is temporarily stored at room temperature. The addition of ammonia to the concentrate offers a precipitation which can be filtered off.