Learn about this topic in these articles:

In separation and purification: Separations based on equilibria
…previously cited involved extraction (liquid-liquid). The other methods are described below.
Read More
In separation and purification: Single-stage versus multistage processes
Consider a liquid-liquid extraction experiment in which the volumes of the two liquid phases (A and B) are equal and in which equal amounts of two components, 1 and 2, are present in one of the phases (say A). If K₁ = 0.5 and K₂ = 2.5,…
Read More

In rare-earth element: Separation chemistry
…Ridge National Laboratory developed the liquid-liquid solvent extraction method for separating rare earths in the mid-1950s. This method is used by all rare-earth producers to separate mixtures into the individual elements with purities ranging from 95 to 99.9 percent. The ion-exchange process is much slower, but higher purities of more…
Read More
In rare-earth element: Solvent extraction
The liquid-liquid solvent extraction process uses two immiscible or partially immiscible solvents containing dissolved rare earths. The two liquids are mixed, the solutes are allowed to distribute between the two phases until equilibrium is established, and then the two liquids are separated. The…
Read More