PROCEDE POUR ELIMINER DES REVETEMENTS D'OBJETS METALLIQUES

摘要

Removal of multiple coatings consisting of >=1 outer organic chemical coating and an inner metal coating from metal objects is described. The objects are treatd in a first soln. in which they are subjected to an ultrasonic field which more or less removes the outer organic chemical coating. The objects are then treated in a second soln. which removes the inner metal coating. Process is esp. sued for treating lacquered tinplate waste. The rate of detinning as well as the amt. of Sn recovered is increased. The metal objects are cooled to a brittle temp. and the non-ferrous particles born by the ferrous objects or fragments are removed in their cooled state by a magnetic device or a vibrating or shock mechanism. The organic chemical coating is a paint or a varnish e.g. acrylic or phenolic. The soln. for removing the Sn-based coating contains NaOH. The objects may also be subjected to an ultrasonic field whilst they are in or passing through the caustic soln. The ultrasonic field acting on the objects in the first or second soln. may comprise two different frequencies. The first soln. may be aq. and contg. a liq. degreasing agent e.g. an alkaline detergent.