A method of enriching the iron content of low-grade iron-bearing ore materials has been developed which produces a high iron ore concentrate suitable for processing into pig iron and steel. The process includes reducing the low-grade iron-bearing ore materials to a fine particulate form and treating a water slurry of this material by applying a combination of ultrasonic treatments in a plurality of high and low intensity magnetic separation operations to remove interfering materials and concentrate magnetic and paramagnetic iron-bearing materials into a high-grade ore stock.