Wetting flotation test

One technology to be tested at the CCTF will be a microbubble flotation process developed by Bechtel National, Inc., of San Francisco. Microbubble flotation is a further development of conventional froth flotation of coal. Froth flotation is a physicochemical process that uses the difference in the surface properties of coal and its associated mineral impurities to effect a separation. An aqueous coal slurry is fed into an aerated tank, where the hydrophobic coal particles become attached to, and are buoyed to the surface by, finely dispersed air bubbles and are collected as a clean-coal-froth product. The mineral matter, being hydrophilic, is wetted by water and remains in suspension to be carried off as refuse. 

The adhesion of specimens subjected to environmental exposure tests was evaluated prior to and subsequent to the contact. Wet thermal shock testing consisted of five cycles each for IS minutes in boiling water and 2 minutes in ice water. The maximum transfer time between the two baths was 30 seconds. Thermal and temperature/humidity exposures were performed in controlled atmosphere chambers for 200 hours. Simulated solder tests comprised immersing the test. specimen in a silicone oil followed by solder flotation. The solder temperature varied from 232 to 288 C and the contact time was S or 10 seconds. In some cases, two flotations were performed on the same sample. The effect of a heat treatment at 135 C prior to solder testing was examined the heat treatment time varied from 0 to 16 hours. ... 

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