Abstract: The present invention relates to a method for determining oxidation of coal, the method comprising: a) mixing a coal sample with an organic solvent and an inorganic solvent, to extract oxidised coal species from the coal sample into a liquid phase, and b) analysing the liquid phase from step (a) to determine a degree of coal oxidation. The inorganic solvent may comprise an inorganic compound such as a pyrophosphate. The present invention also relates to a method for controlling collector used in a coal flotation process, the method comprising determining a degree of oxidation of coal by the preceding method and controlling a ratio of non-polar collector to polar collector in the coal flotation process in response to the determined degree of oxidation of coal.

Abstract: An apparatus (40) for deaerating a froth comprising a spinning basket (44) mounted on a driven shaft (46). The side walls of the spinning basket have a mesh or openings therein. Froth is supplied to the interior of the spinning basket and contacts the floor of the spinning basket and is flung outwardly through the mesh or openings to break the bubbles and deaerate the froth. A solid all (42) may surround the spinning basket to further assist in deaeration. A spinning plate may be used in place of the spinning basket. In another embodiment, vacuum is used to deaerate the froth.