(1) Nickel mattes.
These mattes are obtained by the processing (roasting, smelting, etc.) of nickel ores and consist, according to the ores and processes employed, of nickel-iron sulphides, nickel-iron-copper sulphides, nickel sulphides or nickel-copper sulphides. Mattes are usually in the form of cast blocks or slabs (often broken into pieces to facilitate packing or transport), granules or powders (particularly in the case of certain nickel sulphide mattes). These mattes are used in the production of unwrought nickel.(2) The other intermediate products of nickel metallurgy. These include : (¥¡) Impure nickel oxides, e.g., nickel oxide sinters, nickel oxide in powder form ("green nickel oxide"), obtained by the processing of nickeliferous sulphide or oxide ores. These impure oxides are mainly used in the manufacture of alloy steels. Nickel oxide sinters are usually in the form of powders or in lumps up to 50 mm. (¥¢) Impure ferro-nickel which, because of its high content of sulphur (0.5 % or more), phosphorus and other impurities, cannot be used as an alloying product in the steel industry without prior refining. Refined ferro-nickel is used almost solely in the steel industry to provide the nickel necessary for the manufacture of certain special steels; it is therefore classified as a ferro-alloy in heading 72.02, subject to the provisions of Note 1 (c) to Chapter 72. (¥£) Nickel speiss, i.e., a lumpy mixture of arsenides; it is not now of great commercial importance.
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