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Chapter 74 : Copper and articles thereof
Note.
1. In this Chapter the following expressions have the meanings hereby assigned to them :(a) Refined copper
Metal containing at least 99.85 % by weight of copper; or
Metal containing at least 97.5 % by weight of copper, provided that the content by weight of any other element does not exceed the limit specified in the following table :
TABLE - Other elements | Element | Limiting content % by weight | Ag Silver
As Arsenic
Cd Cadmium
Cr Chromium
Mg Magnesium
Pb Lead
S Sulphur
Sn Tin
Te Tellurium
Zn Zinc
Zr Zirconium
Other elements*, each | 0.25
0.5
1.3
1.4
0.8
1.5
0.7
0.8
0.8
1
0.3
0.3 |
(b) Copper alloys
Metallic substances other than unrefined copper in which copper predominates by weight over each of the other elements, provided that : (ⅰ) the content by weight of at least one of the other elements is greater than the limit specified in the foregoing table; or (ⅱ) the total content by weight of such other elements exceeds 2.5 %. (c) Master alloys
Alloys containing with other elements more than 10 % by weight of copper, not usefully malleable and commonly used as an additive in the manufacture of other alloys or as de-oxidants, de-sulphurising agents or for similar uses in the metallurgy of non-ferrous metals. However, copper phosphide (phosphor copper) containing more than 15 % by weight of phosphorus falls in heading 28.53.
Subheading Note.
1. In this Chapter the following expressions have the meanings hereby assigned to them : (a) Copper-zinc base alloys (brasses)
Alloys of copper and zinc, with or without other elements. When other elements are present :
- zinc predominates by weight over each of such other elements;
- any nickel content by weight is less than 5 % (see copper-nickel-zinc alloys (nickel silvers)); and
- any tin content by weight is less than 3 % (see copper-tin alloys (bronzes)). (b) Copper-tin base alloys (bronzes)
Alloys of copper and tin, with or without other elements. When other elements are present, tin predominates by weight over each of such other elements, except that when the tin content is 3 % or more the zinc content by weight may exceed that of tin but must be less than 10 %. (c) Copper-nickel-zinc base alloys (nickel silvers)
Alloys of copper, nickel and zinc, with or without other elements. The nickel content is 5 % or more by weight (see copper-zinc alloys (brasses)). (d) Copper-nickel base alloys
Alloys of copper and nickel, with or without other elements but in any case containing by weight not more than 1 % of zinc. When other elements are present, nickel predominates by weight over each of such other elements. GENERAL
This Chapter covers copper and its alloys, and certain articles thereof.
Copper is extracted from various ores (see Explanatory Note to heading 26.03) and is also worked up from the metal in its native state, or recovered from waste and scrap.
Copper is recovered from its sulphide ores by a dry extraction process in which the powdered and concentrated ore is roasted where necessary to drive off excess sulphur and smelted in a furnace to produce copper matte or regulus.
In some cases the concentrated ore is smelted in an air or oxygen flash smelting furnace ("flash smelting") without prior roasting.
The matte is treated in a converter to eliminate most of the iron and sulphur and produce "blister copper" (so-called because it has a rough and blistery surface). The blister copper is refined in a reverberatory furnace to produce fire-refined copper and, where required, may be further refined by electrolysis.
For oxide ores and also for certain other ores and residues a wet process (leaching) is used (see Explanatory Note to heading 74.01). Copper is very ductile and malleable; it is, after silver, the best conductor of heat and electricity. It is used in the pure state, particularly in the form of wire for electrical use, or in the form of coils or plates as a refrigerating element, but for general purposes it is mainly used in the form of alloys. Under the provisions of Note 5 to Section XV (see the General Explanatory Note to that Section), the copper-base metal alloys which may be classified with copper include : (1) Copper-zinc base alloys (brasses) (see Subheading Note 1 (a)) in variable proportions of copper and zinc, e.g., common brass, used for many purposes; gilding metal (tombac) used particularly in the manufacture of imitation jewellery and fancy goods.
Copper-zinc alloys containing small quantities of other elements form special brasses, with characteristic properties. Special brasses include high-tensile brass (often known as manganese bronze), used in shipbuilding, as well as leaded brasses, iron brass, aluminium brass and silicon brass. (2) Copper-tin base alloys (bronzes) (see Subheading Note 1 (b)), and sometimes containing other elements which confer special properties. The bronzes include coinage bronze; hard-bronze for gearing, bearings or other machinery parts; bell-metal; statuary bronze; leaded bronze used for bearings; phosphor bronze (or de-oxidised bronze) used in the manufacture of springs and woven wire gauze for filters, screens, etc. (3) Copper-nickel-zinc base alloys (nickel silvers) (see Subheading Note 1 (c)) having a good corrosion resistance and strength. They are used mainly in telecommunications equipment (in the telephone industry inter alia); other uses include use in equipment for instrument parts, taps and high quality plumbing hardware, slide fasteners, various applications in the electrical field such as clamps, springs, connectors, receptacles, etc., ornamental and architectural metalwork and chemical and food processing equipment. Certain grades of these alloys are also used in the manufacture of tableware, etc. (4) Copper-nickel base alloys (cupro-nickels) (see Subheading Note 1 (d)), which often contain small amounts of aluminium or iron. They represent a family of alloys featuring resistance to the corrosive effects of sea water and, therefore, find wide use in a variety of marine or shipbuilding applications, particularly for condensers or piping, and in the manufacture of coins or electrical resistors. (5) Aluminium bronze composed essentially of copper with aluminium and employed in engineering where high strength properties, corrosion resistance and hardness are important factors. (6) Beryllium copper (sometimes known as beryllium bronze) composed essentially of copper with beryllium and, because of its hardness, high strength and resistance to corrosion, used for springs of many types, as moulds for plastics, as resistance welding electrodes, and for non-sparking tools. (7) Copper-silicon consisting essentially of copper and silicon and having high strength and resistance to corrosion. It is used, e.g., for the manufacture of storage tanks, bolts and fasteners. (8) Chromium copper mainly used for resistance welding electrodes. This Chapter covers : (A) Mattes and other intermediate products of copper metallurgy and unwrought copper and waste and scrap (headings 74.01 to 74.05). (B) Copper powders and flakes (heading 74.06). (C) Products generally obtained by rolling, extruding, drawing or forging the copper of heading 74.03 (headings 74.07 to 74.10). (D) Various articles specified in headings 74.11 to 74.18 and other articles falling in heading 74.19 which covers all other copper articles other than those covered by Note 1 to Section XV or those included in Chapter 82 or 83, or more specifically covered elsewhere in the Nomenclature.
The products and articles of copper are frequently subjected to various treatments to improve the properties or appearance of the metal, etc. These treatments are generally those referred to in the General Explanatory Note to Chapter 72, and do not affect the classification of the goods. The classification of composite goods, particularly made up articles, is explained in the General Explanatory Note to Section XV.
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Section 15 Base metals articles
> Chapter 74 Copper
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