Abstract: A vibratory plating apparatus having a plating liquid in a plating container, a base on which the container is mounted for vibrating movement, and a lid for the top of the container. The bottom of the container has an arcuate bottom. A vibration motor vibrates the container and electrodes are disposed within the container. With this plating apparatus, workpieces can be plated uniformly in a very short period of time at a high current density and with a small amount of plating liquid. Moreover, it eliminates troublesome steps of manually suspending and removing workpieces from hangers.

Abstract: A sludge containing a sparingly soluble metal compound such as nickel carbonate or the like is supplied to an anode compartment or an intermediate compartment of an electrolytic cell provided with an anode compartment and a cathode compartment or with an anode compartment, an intermediate compartment and a cathode compartment each sectioned by a filter membrane or an ion-exchange membrane, and thereafter an electrolytic treatment is conducted by using an insoluble electrode as anode and a usual electrode as cathode to precipitate a metal such as nickel on the cathode. Effective recovery of a metal is attained directly from a sludge by way of electrolysis.