Method of separating materials in a flotation reactor

A method of separating desired material from sterile or undesired material comprising the steps of:

• forming a slurry of material having portions of desired and undesired material to be separated;
• introducing the slurry into a reactor chamber having a lower part, a middle part, and an upper part aligned along a central axis, the upper part having a vertically narrowing section, along the central axis thereof;
• generating a foam external of the reaction chamber, said foam comprised of bubbles of a controlled size;
• introducing the foam into the lower part of the reactor chamber;
• dispersing the slurry into the foam by passing the slurry and foam through a rotatable member in the lower part of the reactor chamber such that the foam is substantially homogeneously dispersed into the slurry as the foam in contact with the aforesaid slurry ascends through the middle part of the reactor chamber to the upper part thereof for a sufficient time to permit particles of the desired material in the slurry to adhere to the bubbles in the foam;
• and
• providing a controlled stream of water to the foam in the upper part of the reactor chamber in the vertically narrowing section to cause separation of undesired material from the particles of the desired material.