Page 23 - Handbook of Gold Exploration and Evaluation

6 Handbook of gold exploration and evaluation

Commercial applications

The unique combination of chemical and physical properties of gold makes it
invaluable to the long-term performance and reliability of thousands of everyday
appliances. The metal is completely recyclable and is a vital component in many
medical, industrial and electrical applications. It is one of the least active metals
chemically; it does not tarnish or oxidise in air, is unaffected by temperature
change and is inert to all strongly alkaline solutions and to all pure acids, except
selenic acid. Pure gold has a density 19.3 times that of water and weighs about
3
3
19,000 kg/m (1,200 lbs/ft ).
Gold alloys are used in industrial applications such as electroplating,
granulation, pressing and lamination to keep costs down and make the product
harder. The largest demand for gold comes from the electronics industry and the
weapons and aerospace industry. Because of gold's resistance to corrosion and
high electrical conductivity, it is used extensively in the manufacture of con-
nectors, printed circuits, semi-conductors, relays, switches and a host of other
electronic products. Properties of radiant energy unique to gold have led to the
development of efficient energy reflectors for infra-red heaters and cookers and
for focusing and heat retention in metallurgical processing. The extraordinarily
high reflective powers of the metal are relied upon in the shielding that protects
spacecraft and satellites from solar radiation. Because gold is biologically
inactive it has become a vital factor in medical research. Tiny metallic gold
particles are used diagnostically in prostate cancer treatment and gold com-
plexes of thiols are used for the treatment of arthritis by injection into the site of
inflammation. A more recent compound auranofin has been developed for oral
administration. Radioactive 198 Au, with a half-life of 2.7 days is increasingly
important for medical diagnosis and radiation therapy, and as a tracer in
industrial applications such as monitoring sediment movement on the sea floor.
Gold is the most malleable and ductile of all metals and can be flattened into
thin sheets less than one millionth of an inch thick and drawn into wire weighing
only 0.5 mg/m length. Fabrication and other end uses of gold are for jewellery,
electronics, coinage and other industrial and decorative purposes. Uses of gold
for industrial and decorative purposes include brazing alloys, decorative plating,
liquid gold for ceramics, rolled gold for fountain pens and gold used in the
production of industrial laboratory chemicals. Italy has the largest gold jewellery
manufacturing industry in the world and substantial portions of its gold imports
are exported in the form of finished jewellery. The USA is the next largest
producer of jewellery, then Germany, Japan, France, Switzerland and Canada.
The use of gold for the fabrication of medals, medallions and coins, after
showing a decline in 1982, increased markedly in 1983 when South Africa
became the largest individual manufacturer of these items. An undisclosed
amount of gold is also issued (apparently with governmental consent) as coins
for local use by business organisations and wealthy classes in some Asian