Cell configuration for apparatus for electrolytic recovery of silver from spent photographic processing solutions

Novel apparatus of the rotating cathode type for the electrolytic recovery of silver from spent photographic processing solutions is disclosed. The apparatus comprises a tank, at least one cylindrical cathode carried for rotation in the tank about a vertical axis, and for each cathode, at least one vertically disposed slat-like anode positioned with respect to the cathode surface so as to define a vertically elongated venturi between the cathode and the anode, the narrowest section of each venturi being substantially along a vertical edge of each anode, and preferably being not substantially more than about one inch in dimension. Each anode preferably is substantially parallel to a tangent drawn to the cathode surface opposite the vertical edge of the anode at the narrowest section of the venturi. The vertical edge of each anode at the narrowest section of the venturi preferably has a ninety-degree or sharper corner, whereby the strength of the electric field is concentrated in the region of the venturi. The cross-sectional area of the cathode or cathodes is preferably at least ten percent of the cross-sectional area of the tank, for good mass transfer of solution in the apparatus.