Pollution Prevention and Control Technologies for Plating
Section 3 - Chemical Recovery
3.5.2 Development and Commercialization
Electrowinning is presumed to be one of the earliest methods of
metal recovery used in the plating industry, although no specific
reference to its use prior to the 1960's was found (ref. 128).
One of the reasons for its presumed early development and current
widespread use is the fact that this process emulates the electroplating
process. As such, it is readily accepted and understood by the
plating industry. Further, for these same reasons, there are fewer
system failures caused by misapplications or operational errors
than with other recovery technologies such as ion exchange or
membrane technologies. The electrowinning technology also has
technical roots and contemporary applications in other industries,
including electrorefining of copper, extraction of metallic aluminum
from bauxite, and recovery of silver from photographic film manufacturing
and developing operations.
Electrowinning can be performed using very simple equipment. As
such, many plating shops have constructed units in-house. The
effectiveness of these home-made units varies from shop to shop.
Commercial units for plating applications are manufactured/sold
by at least 40 companies (ref. 421). Many of these units, like
the home-made models are also relatively simple in design. As
discussed in Section 3.5.1, the efficiency
of the electrowinning process is impacted by several electrochemical
factors. Some commercial units, through the incorporation of more
sophisticated design elements, minimize the impact of the electrochemical
forces that reduce plating efficiency. Typically, these design
elements are limited to the commercial units and are not found
to any significant extent with the home-made versions.
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