In metallurgy, a heavy suspension method for the concentration of ores in which the waste has a specific gravity of 2.7 or more. Minerals having a specific gravity in excess of 5.25 must be used, since a suspension containing over 40% solids by volume is too plastic for use. Galena (sp gr, 7.4 to 7.6) and ferrosilicon (sp gr, 6.7 to 7.0) have been used.