Magnesium smelting: bans on use of sulphur hexafluoride

Find out when you can't use sulphur hexafluoride (SF6) to smelt magnesium, and about your obligation to prevent leaks of SF6 and other gases.

This guidance was withdrawn on

Sulphur hexafluoride (SF6) is often used as a ‘cover gas’ during magnesium smelting, to prevent the molten magnesium from reacting with oxygen.

Bans on use of SF6

You can’t use more than 850 kg SF6 in a year at a facility that carries out either:

  • die casting operations
  • recycling of magnesium die casting alloys

From 1 January 2018 you won’t be able to use any SF6 in such facilities.

The EU’s 2006 regulation only restricted use of SF6 in die casting operations. The bans on the use of SF6 in the recycling of magnesium die casting alloys are new to the 2014 regulation.

Prevent leaks

You’re legally required to take precautions to prevent gas leaks if you use any F gas regulated by the EU at your facility.

F gases regulated by the EU that are relevant to magnesium smelters include:

  • SF6
  • hydrofluorocarbons (HFCs) that are used as replacements for SF6, eg HFC 134a

This applies to facilities of any size, carrying out any magnesium smelting operations.

Your precautions should be technically and economically feasible. Contact the Environment Agency, if you’re not sure if you’re taking enough precautions.

Published 31 December 2014