2620 11 00: Arsenik, metaller veya bunların bileşiklerini içeren cüruf: galvanizli matlar

Hard zinc spelter is a residue from galvanising baths and is often referred to as galvanisation matte. There are two principal kinds:

1. Mattes from heavy galvanisation which are metal products of a very variable and non-homogeneous composition, less easily melted and denser than zinc, and which settle at the bottom of the baths of liquid zinc during galvanisation of steel sheets, wire, pipes, etc. in molten zinc.

These mattes are drawn from the bath in a thick paste and are moulded in the form of sheets or slabs, which may have a rough, or even a spongy, appearance.

They contain, by weight, from 2 to 5 % of iron. Their zinc content varies from 92 to 94 % by weight. Their aluminium content is generally low and does not exceed 0,2 to 0,3 % by weight.

2. Mattes from light galvanisation or ‘surface mattes’ which are metal products from continuous skimming of the galvanisation baths by the Senzimir process, not containing flux.

These mattes, which are less dense than zinc, float on the surface of the baths. When drawn from the baths in a thick paste and moulded into slabs, they have a less irregular appearance than those mentioned above.

Their iron content is very low, generally less than 0,5 % by weight. Their aluminium content is much higher: 1 to 2 % by weight. Their zinc content is of the order of 98 % by weight.

These should not be confused with zinc alloys (heading 7901), which assay by weight generally from 3 to 5 % of aluminium and can contain up to 3 % by weight of copper, but which comply with specific technical requirements, whereas the composition of zinc mattes is such that they can be usefully employed only for metallurgical or chemical transformation.