260 Refining Used Lubricating Oils
When the ow rate of oil through the lter had decreased to 70% to 80% of the
initial ow rate, a solvent cleaning cycle was initiated in which the solvent ows
through the lter unit and returns to the solvent holding tank while the permeate
lines from the lter are isolated. No information was given on the possible recovery
of the solvent or its disposal.
The permeate through the lter, having a color and smell very similar to that of
the used oil, then passes to a clay treatment section. After testing various adsorbent
clays for their ability to remove the color and smell of the permeate oil, as well as
their ability to be regenerated, an anionic clay powder of hydrotalcite was found to
be effective, operati ...