Electrochemical cell, esp. for silver recovery - from fixer soln., has cylindrical electrodes between which soln. is circulated

摘要

An electrochemical cell for precious metal recovery from soln. has two radially-spaced concentric, cylindrical electrodes one of which is totally immersed in the soln, is spaced from the cell bottom and is open at its ends to allow vertical passage of soln. A device is provided for circulating the soln. in a toroidal path about the totally immersed electrode such that the soln. circulates upwards in the space between the electrodes. This device may comprise blades, which rotate below the surface of the soln, or the electrodeposition voltage supply to the electrodes, which causes density changes in and hence circulation of, the soln. as the precious metal plates out. The electrodes are pref. made of stainless steel. The cell is esp. useful for small establishments, such as hospitals, for silver recovery from photographic and radiographic fixing solns. The cell has a simple design, gives more than 98% silver recovery, allows reuse of the electrodes and recycling of the fixing soln, avoids liberation of gases into the environment and does not cause deterioration of the soln. or silver by excessive current at high voltage.