Zinc

Zinc ores are fairly widespread in nature and abundantly distributed throughout the world, but seven countries account for nearly 75% of world production of zinc concentrates.
Zinc ores are commonly associated with copper, lead and gold ores and are often produced as a co or by product. The main ore mineral of zinc is sphalerite (Zn,FeS). Smithsonite (ZnCO3), willemite (Zn2SiO4) and hemimorphite (Zn4Si2O7(OH)2 H2O) may occur in the near-surface weathered or oxidised zone of an orebody.

Sphalerite, called also blende or "black Jack”, with a cubic structure is the most abundant zinc mineral. Together with marmatite (Zn, Fe)S, smithsonite and hemimorphite, blende accounts for practically the hole of world zinc reserves.
Zinc metal is a bluish-white lustrous metallic element that crystallizes in the hexagonal system. It is rather brittle at ordinary temperatures but malleable between 100 and 200°C.

Zinc is the third most used non-ferrous metal (after aluminium and copper). It is primarily used for coating iron and steel products in order to protect them against corrosion. This zinc coating is known as galvanising and represents about 40% of the end use for zinc. Zinc is also a major product in brass alloys, die casting alloys, chemicals and rolled zinc products.

The metallurgy of zinc depends upon the ore used. The sulfide ore is roasted to the oxide, then mixed with coal and heated to 1,200°C. The zinc vaporizes and is condensed outside the reaction chamber and cast into blocks called spelter. In another method the ore is processed by flotation, filtering, roasting, and leaching; the resulting solution is filtered and the zinc removed by electrolysis.


Links:
-World Bureau of Metal Statistics - Statistics 2002 - 2003
-IZA-The International Zinc Association,
-ILZSG-International Lead and Zinc Study Group




Zinc Production
Thousand Tonnes