The smelter at Rio Tinto Alcan in Northumberland will be closed within the next hour.
Alcan worker, Paul Scott, says "it's the end of hot aluminium smelting in England".
More top news
Emma Jesson brings you Saturday night's forecast
Sandiford, a former legal secretary originally from Redcar, was convicted of drug smuggling offences and sentenced to death in 2013.
Durham Crown Court heard that one of the male victims suffered a triple-fractured jaw, while left lying in the gutter, unconscious.