australia's identified mineral resources 2005 - Geoscience Australia

AUSTRALIA’S IDENTIFIED MINERAL RESOURCES 2005
Zinc, Lead, Silver
The construction and appliance manufacturing industries use large amounts of zinc, mainly as
coatings on steel beams, sheet steel and vehicle panels in the automotive industry. It is also used
in alloy die cast products, zinc pigments, zinc salts, zinc oxide as additives to rubber and for zinc
chemicals in agriculture, and for wrought or rolled zinc products.
The widespread occurrence, relatively simple extraction, and combination of desirable properties
have made lead useful to humans since at least 5000 BC. In deposits mined today, lead (in the form
of galena, PbS) is usually associated with zinc, silver and commonly copper, and is extracted as a
co-product of these metals. More than half of the lead utilised today comes from recycling, rather
than mining. The largest use is in batteries for vehicles and communications. Less important uses
include cable sheathing, solder, casting alloys, chemical compounds, ammunition, glass in TV and
computer screens for radiation protection, and ceramics. Its use as a petrol additive has declined
significantly with the gradual introduction of lead-free petrol worldwide. New uses for lead could
be in large storage batteries used for load-levelling of electrical power and in electric vehicles.
The relative scarcity, attractive appearance and malleability of silver make it suitable for use in
jewellery, ornaments and silverware. Its extensive use in coins throughout history has declined over
the last forty years. In Australia, the 1966 fifty-cent piece was the last coin in general use to contain
silver (80% silver, 20% copper). Silver is mined and produced mainly as a co-product of copper, lead,
zinc, and to a lesser extent, gold. Today, photographic paper and film, followed by the electronics
and jewellery/tableware industries are the most important users of silver. Demand for silver as an
anti-bacterial agent is likely to double over the next few years as its use increases in water treatment
(as an ioniser with copper in domestic swimming pools) and for biocide and bacteriostatic activity in
plastic and textiles formulations. Silver based biocides are also being tested as a replacement for
arsenic based preservatives in wood treatment.
Resources
Australia’s total resources of zinc, lead and silver increased in 2004. Total identified resources of zinc
increased by almost 10 Mt to 89.3 Mt of contained zinc; lead from 55.2 Mt to 56.8 Mt of contained
lead; and silver from 107.3 kt to 109 kt of contained silver.
ZINC
EDR of zinc at 41 Mt is the world’s largest holding, accounting for over 18% of world’s total.
Queensland remained pre-eminent, its EDR increasing from 20.5 Mt to 26.6 Mt (65% of EDR).
The rise in EDR was affected predominantly by reclassification of resources and improved grades
at Mt Isa and George Fisher (including the Hilton orebody), while resources in other deposits were
unchanged. The Northern Territory at 9.4 Mt again had the second largest EDR and its share of
the total category was 23% compared to 29% in 2003. New South Wales had the third largest EDR
with 2.7 Mt (2.8 Mt in 2003). The decrease was primarily due to depletion of resources through
production. Western Australia's EDR increased to just under 1.5 Mt, (1 Mt in 2003), mainly through
reclassification of resources at the Jaguar deposit. Victoria remained unchanged at 0.39 Mt. Tasmania's
EDR increased to 0.43 Mt (0.29 Mt in 2003).
Of Australia’s EDR of zinc, over 50% is in JORC ore reserve categories, compared to almost 65% in
2003. The ratio of EDR to production is just over 30 and ore reserves to production close to 16.
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Paramarginal demonstrated resources of zinc increased from 6.3 Mt to 8.5 Mt due to reclassification of
the Mt Isa and George Fisher resources. Submarginal demonstrated resources fell slightly from 16 Mt
to 15 Mt over the year. These variations are attributed to relatively small changes in most states and
the Northern Territory.
Total inferred zinc resources decreased by 20% to 25.2 Mt in 2004 following the reclassification of
resources, particularly Mt Isa and George Fisher.