Method for producing a constant valuable mineral content in concentrate that is formed by flotation

The invention relates to a method for adjusting the valuable mineral content in concentrate formed by floatation to a range such that the ratio between yield and content is optimized. The method of adjustment is intended for use in all types of flotation machines. The method serves to adjust the retention time of the froth bubbles in the froth bed to an optimum range and to adjust the thickness of the froth bed, the rate of increase of the floatation air or the froth area, either together or separately. The essential characteristic of the method is that the ratio between the adjusted parameters is determined by the value υ f, which denotes the air retention time in the froth bed.