The feed material, from which the volatile compounds are to be removed, is fed into the top of the column. This material, either liquid or slurry, flows as a thin film down the upper surface of the first stationary cone. It then drains through the outlet of the stationary cone on to the base of the spinning cone immediately below. Centrifugal force, generated by the rotation of the cone, causes the liquid to flow upwards and outwards across the upper surface of the spinning cone, again as a thin film.