1999 marked the 50th anniversary of the Outokumpu flash-smelting process. O
riginating during the post-World War II energy crisis, flash smelting is a
high-intensity process developed to attain ever-increasing throughputs and
intensities. Many innovations and intensities. Many innovations and continu
ous development ensued during the next 50 years before today's state-of-the
-art copper-making process chain and environmental benchmarking technology
(e.g., Outokumpu flash smelting, Kennecott-Outokumpu flash converting, and
flash technology) became possible. This article reviews how Outokumpu flash
furnace design, especially cooling for higher heat loads, has improved ove
r the years.