Iron impurities may be removed from volumes of molten aluminum or magnesium metals or alloys by applying a static magnetic field gradient to each of the molten metal volumes, or melts. The magnetic field gradient is applied to each of the melts so that separate-phase iron impurities suspended therein will move in the direction of the applied magnetic field and become concentrated in a predetermined region of the of the melts, thereby forming an iron-rich region. The remaining iron-depleted region of each of the melts can be physically separated from the as-formed iron-rich region and cast into shaped articles of manufacture or into semi-finished articles for further processing. Such articles will have a lower iron-content than the original molten metal volumes.