who needs a sacrificial carbon anode.
Apple put $13 million into replacing a material aluminum smelters burn through every 25 days. The first batch of carbon-free aluminum went into a MacBook Pro. Global aluminum production is 73 million tons a year. Hall-Héroult has been the only way to make aluminum since 1886. It has two carbons: the electricity it pulls, and the anode that burns up in the cell. A 415 kg carbon block dissolves every 25 days. That's 1.5 tons of CO2 per ton of metal, before counting the power source. Replacing the carbon anode is one of the hardest materials-science problems in extractive metallurgy. It requires a material that survives 960°C molten cryolite for years without contaminating the metal. Parts per million of iron degrades the aluminum. The replacement is a cermet: nickel ferrite ceramic with a copper alloy binder. Alcoa worked on the materials science for four decades. Rio Tinto had the cell design. Apple brokered the partnership in 2018. Last November, Elysis ran a 450 kA cell at Alma, Quebec. The anode emitted oxygen instead of CO2. It lasted 30 times longer than carbon. The first new aluminum chemistry in 140 years.
