Zinc mines are located throughout the world, with the largest producers being China, Australia and Peru.  In 2005, China produced almost one-fourth of the global zinc output.[1] Smelting and extraction of impure forms of zinc was accomplished as early as 1000 AD in India and China. In  the West, impure zinc as a remnant in melting was usually discarded as worthless.  Worthless, until it was discovered that zinc was an excellent barrier against corrosion for other metals.  Zinc became useful as the sacrificial metal.  Later, numerous uses were discovered making zinc the fourth most common metal in use behind iron, aluminum, and copper.

 

In principle, zinc is viewed as more difficult to electrowin than copper because zinc lies considerably above hydrogen in the electrochemical series, whereas copper lies below.  Hydrogen evolution on a zinc surface is a very slow process and zinc can be electrodeposited from acid solutions.  Electrolyte zinc sulfate solutions must be very pure for electrowinning to be at all efficient.  Impurities can change the decomposition voltage enough to where the electrolysis cell produces largely hydrogen gas rather than zinc metal.[2]  These impurities might include magnesium, manganese, antimony, arsenic, copper, and nickel.  Not only would these elements contaminate the zinc product if they are present in significant quantities, but also diminish the current efficiency of electrolysis to deposit zinc.  This means that the solution needs to be purified before electrolysis.[3]

 

Learn More...APUŽ Acid Purification Unit