Removal of Magnetite from Sample Mixtures

A separation apparatus, comprising:

• a vertically-oriented first tube having an inside diameter and a height;
• a second tube having an outside diameter substantially smaller than the inside diameter of the first tube and substantially the height of the first tube, the second tube concentric with the first tube, the tubes having a common center-line;
• a spiral track implemented between the inside diameter of the first tube and the outside diameter of the second tube, the spiral track descending along substantially the height of the first and second tubes;
• and
• a plurality of magnet assemblies, individual ones of the magnet assemblies positioned on an outside wall of the first tube, providing magnetic fields through the outside wall of the first tube into regions where the spiral track meets the inside diameter of the first tube;
• wherein a material mixture comprising magnetic particles is introduced at an upper end of the apparatus, entrained in a flow of water down the spiral track, and some of the magnetic particles are separated from the material mixture and retained in the magnetic field of individual ones of the magnet assemblies.