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Substance: Zinc desilversing skims

 

“Zinc, desilverising skims are formed when solid zinc is added to molten lead bullion with a significant amount of silver and/or gold. Zinc desilverising skims consist mainly of metallic lead and silver-zinc alloys. A lighter intermetallic phase mainly consisting of zinc, silver and lead forms on the surface, from which it is skimmed. Further processing by physical means can be used to reduce the lead content, as well as the content of some impurities, without chemically altering the zinc/silver/lead phase.”

EC names

EC number/ EINECS No.

CAS No.

Zinc desilverising skims

273-802-3

69029-60-3

Silver crusts

273-799-9

69029-57-8

Note: substances pre-registered under the EC numbers 273-802-3 and 273-799-9 were merged as a result of sameness discussions within the relevant SIEFs. They are collectively identified under the name Zinc desilverising skims and the EC number 273-802-3.

Zinc desilvering skims is a (metallic) grey, odourless solid (at 20°C and 101.3 kPA) in massive form. The density will vary according to the precise composition of the sample. The density of the tested sample was 9.76 g/cm3. The melting point is shown to be ca 316°C. Consequently, boiling point and vapour pressure cannot be determined. The water solubility test shows dissolution of metal ions although these results should be used with caution.

 

There is no evidence of physical hazards in terms of (auto)flammability, explosivity and oxidizing properties.

Studies regarding flash point, partition coefficient, surface tension and particle size distribution do not need to be conducted.

Waivers are in place for all these endpoints.

 

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