Lead is derived from the Latin word “plumbus”; hence the symbol
Pb. Lead is a dense, malleable bluish-grey metal whose physical and chemical
properties find application in a variety of uses in the manufacturing,
construction and chemical industries. The manufacture of lead - acid storage
car batteries (70%), chemical industries, sheet and extrusions and cable
sheathing dominate the end uses of lead. Environmental regulations
(particularly in the western world) are now controlling the role of lead end
products such as tetra ethyl, paint and as a petroleum additive. Lead is also
used as a shield against gamma radiation and therefore finds itself used in
shielding X-Ray equipment and at nuclear installations.
A large amount of lead is recycled (from old car batteries); therefore there
is quite a large “secondary” lead production (amounting to 50% of
global production). The most common ore forming lead mineral is galena (PbS)
and is often found associated with other metals such as zinc, silver copper.
Cerussite (PbCO3) and anglesite (PbSO4) commonly occur in the near-surface
weathered or oxidised zone of a lead orebody. Australia, China and the USA are
the world’s major producers of lead. Plastics can be used as a substitute
for lead products in a variety of applications such as electrical cable
coverings, building construction and containers. Aluminium, tin and plastics
compete with lead in packaging and protective coatings.
Zinc (Zn) is mainly used for coating iron and steel products in order to
make them corrosion resistant. 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.
Zinc ore is commonly associated with copper, lead and gold ores and is 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. Australia, Canada and China are the world’s major producers of
zinc.
Aluminium alloys, plastic coatings and magnesium can be used as substitutes
for zinc in a wide variety of applications.
