Electrodeposition of metals from dilute solutions of their ions

Abstract

The possibility of recovering metals from dilute solutions of their ions is examined using the deposition of copper from acidic cupric. suipbate solutions as the test reaction and the fluidised bed electrode as the electrochemical reactor. Practical design -aspects, together with an explanation of the behaviour of fluidised bed electrodes are sought. Thus, reactor and distHbutor design, current efficiencies and electrode potentials are examined under diverse experimental conditions of bed expansion, copper concentration, particle size and diaphragm current density. A mathematical model is used to interpret theoretically the electrode potentials and in its light several facts emerge. It is concluded that fluidised beds are suitable for metal deposition from dilute solutions, high current efficiencies are obtained and their cost compare favourably with plate electrodes. The-liMitations are also emphasised, particularly electrode thickness and relatively low bed expansions. On the theoretical side, it is shoxm that the fluidised bed system is essentially dynamic and its explanation in fundamental. terms require a different approach from the ones used so far. Very elementary experiments are described and the results show the way in uhich further work should be carried out.