When designing liquid-liquid extraction columns, one of the key steps is to calculate the number of equilibrium stages needed. For many systems it cannot be assumed that the carrier and the solvent are not mutually soluble. Therefore, a simply binary McCabe-Thiele style method cannot be used, and a ternary Hunter-Nash construction method must be used.
The video below gives a summary of the Hunter-Nash method and an example use of this.
The graph below shows an example Hunter-Nash graph. The key design parameters can be varied to help understand how they affect the design.