The U.S. EPA presented awards to three companies for phasing out or replacing sulfur hexaflouride (SF6) in magnesium production and casting processes as part of the SF6 Emission Reduction Partnership effort.
SF6 is the most potent greenhouse gas and is nearly 24,000 times as effective at trapping heat in the atmosphere as an equivalent amount of carbon dioxide.
Lunt Manufacturing conducted trials of three promising alternative melt production technologies. The tests conducted at Lunt included AM-Cover, MTG-Shield with Novec 612 and dilute sulfur dioxide (SO2). Technicians used sophisticated analysis equipment to monitor the rates of reaction, potential creation of any by-product gases, and the melt-surface conditions. And, the SF6 was analyzed as a proper benchmark.
Molten magnesium may be highly volatile when it oxidizes, and magnesium-oxide formation can reduce the finish quality and or strength of the finished products. Magnesium diecasters and others have used SF6, sulfur hexafluoride, for several decades as a cover gas to shield the molten metal from air.
Sulfur hexafluoride is the most potent green gas, according to the Intergovernmental Panel on Climate Change: it assigns to SF6 a global warming potential of 22,200 times that of CO2 over a 100-year period, though its mixing ratio in the atmosphere is far lower than that of CO2. The EPA maintains active partnership programs with the two largest SF6 emission sources electric utilities and the magnesium industry,, which has committed to phase out SF6 emissions by 2010.