New Static Flotation Technique Increases Mineral Recovery and Quality

An interesting new flotation technique which reportedly improves mineral recovery over an extended particle size range-from 3 mm to 5 microns and below-has been developed by the Institute of Physical Chemistry, Bulgarian Academy of Sciences. Designated the "static" flotation technique, it is suited for upgrading tin, molybdenum, tungsten, uranium, gold, copper, lead, zinc, and other metallic ores. Recoverable nonmetallics include feldspar, sulfur, and phosphorite. Characteristic of the static flotation process are: •longer contact period (up to 1000 times longer between particles and bubbles, •low collision velocity and inertial forces between the contact and aeration in a thin pulp layer, • aeration without the harmful hydrodynamic repulsion upon particles below 5 microns (the pulp layer is only a few millimeters thick and rising bubbles collide with the particles either directly or in the thin foam films formed), •option to conduct the process with or without froth by film flotation at equilibrium contact angles, and • the use of inexpensive frothers and/or unstable froth with separate regulations of froth stability by hydrodynamic, ultrasonic, or electrostatic means.