Zinc ash, What is it?

• Zinc ash is oxidised zinc that forms on the surface of molten zinc metal.
• The ash consists of a powdery material (the ash proper) and solid metallic pieces of an irregular shape.
• It is sometimes called zinc dross, zinc skimmings, zinc top dross or zinc oxide. In the galvanising industry itself, the term zinc ash prevails.
  
  

Source of Zinc Ash?

• Zinc ash usually arises from hot dip galvanising or other zinc coating processes.
• The ash is removed from the top of galvanising baths by skimming or straining.

What can you do with Zinc Ash? There are several major companies that process or recycle zinc ash. Some companies mechanically separates the metallic zinc from the ash. Others do this and blends the zinc ash to make agricultural grade zinc oxide.

• A number of galvanising companies also mechanically separate the metallic zinc from the ash.
• The metallics are re-used in galvanising and other processes.
• Many companies smelt both processed ashes and unprocessed ash to recover the zinc in metallic form.
• Export or import of zinc ash without a permit contravenes the Hazardous Waste (Regulation of Exports and Imports) Act 1989.
  
  Is it hazardous & if so,  why?
  

  Zinc ash frequently contains lead at concentrations that make it hazardous to humans, other animals and plants. Occupational Health and Safety organizations around the  world have classified materials containing lead compounds at concentrations greater than 0.5% as designated hazardous substances. Lead can leach out of zinc ash into the environment and there are tests which may be used to determine whether or not this may happen in particular circumstances. Work-place controls are a must in factories that recycle and process zinc ash.