Abstract: A method and apparatus for monitoring the operation of a froth flotation process comprises sensing variations in solids content of the input stream to the process, varying the dosage of flotation reagent employed in accordance with the input variations, sensing variations in solids content of at least one of the output streams after a predetermined time lapse, comparing the input and output readings with control data relating input and output solids content, and re-adjusting the dosage of flotation reagent dependent on the difference between the actual readings and the control data.