Page 12 - Curriculum Visions Dynamic Book

Electrical refining of copper
Even the best of chemical reactions cannot completely remove all of the impurities in a metal, so ores refined in a furnace do not produce pure metals. This is why many metals are refined to their final stage of purity by electrical means in a process called electrolysis.
Impure copper from the furnace is used as one of the electrodes
of an electrolysis cell. The other electrode is made from a thin sheet of pure copper. The copper is then refined by placing the two electrodes in a copper sulphate bath and
passing a current between
them. The impure copper
on the anode corrodes, and
copper ions pass through the
electrolyte, collecting on the
cathode sheet as pure copper.
When the cathode has acquired a sufficient thickness of pure copper, it is lifted
from the electrolysis cell and replaced with a new electrode. Similarly, when the anode has corroded completely away, it is replaced with a new ingot of smelted metal. The cathodes are then melted down and made into wire and sheet metal.
The laboratory demonstration of electrolysis and the giant industrial equivalent are shown
on these pages.
 Copper cathodes, heavily plated with copper, are lifted from the electrolytic cells.
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