Market Survey on Copper - Indian Bureau of Mines

ii) Manganese bronze (high strength brass) and leaded manganese bronze
(High tensile brass)
iii) Copper-zinc-silicon alloys (Silicon brass and bronze) and
iv) Cast Copper-bismuth & Copper-bismuth-selenium alloys
IV) Bronzes- The term bronze originally describe alloys with tin as the only
principal alloying element. The wrought bronze alloys include (a) Copper-Tin-
Phosphorus alloy (Phosphor bronzes) (b) Copper-tin-lead-phosphorus alloys
(leaded phosphor bronzes) (c) Copper-aluminium alloys (aluminium bronzes)
and (d) Copper-silicon alloys (silicon bronzes). The cast bronze alloys
include (a) Copper-tin-alloys (Tin bronzes) (b) Copper-tin-lead alloys (leaded
& high leaded tin bronzes) (c) Copper-tin-nickel alloys (Nickel-tin bronzes)
and (d) Copper- aluminium alloys (aluminium bronzes).
There are some more alloys made of copper namely copper-nickel alloys,
copper-nickel-zinc alloys or ‘nickel silver’, leaded copper-20% or more lead, etc.
2.2 CLASSIFICATION AND GRADES
2.2.1 American Standard
Copper is classified according to the method by which it is refined, and
is specified as fire-refined copper, electrolytic copper and chemically refined
copper. Fire refined copper is produced from crude copper by
pyrometallurgical process.
Some grades of fire-refined copper can be used as electrical conductor,
but most are used for alloying. Most electrolytic copper is produced by
electrolytic anode-to-cathode transfer of metal through a copper sulphate
solution.
Cathode copper has become the single most important commercial form
of copper and it accounts for nearly three-fourth of the refined copper consumed
annually.
A considerable quantity of refined copper is settled and cast into various
refinery shapes for consumer use. Commercially, this type of copper is
classified by the method of processing. During melting and casting of final
shapes, the amount of oxygen absorbed has a critical influence on the
properties of the metal. Accordingly, apart from cathode, there are three basic
classes of commercial copper.
(a) Tough-pitch copper, which is electrolytic or fire-refined copper cast in
refinery shapes and containing 0.02 to 0.05 per cent oxygen as cuprous oxide.
(b) Oxygen-free copper, which is refined copper under deoxidising
atmosphere.
(c) De-oxidised copper, which is refined copper free from cuprous oxide
through the use of deoxidisers
The details of classification are given in Table: 2.2.
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