Froth flotation is a process for selectively separating hydrophobic materials from hydrophilic. .. Normally the setup is a twostage system with 3,4 or 5 flotation cells in series. .. properties of the solution. pH modifiers include lime (CaO), Soda ash (Na2CO3), Caustic soda (NaOH), sulfuric and hydrochloric acid (H2SO4, HCl).