Froth flotation is a process for selectively separating hydrophobic materials from hydrophilic. This is used in several processing industries. Historically this was first used in the mining industry, where it was one of the great enabling technologies of the 20th century. It has been described as "the single most important operation used for the recovery and upgrading of sulfide ores". The development of froth flotation improved the recovery of valuable minerals, such as copper- and lead-bearing minerals. Along with mechanized mining, it allowed the economic recovery of valuable metals from much lower grade ore than before.