96 Refining Used Lubricating Oils
burners and boilers; (2) lubricating oil, which is a preferential product insofar as base
oils are premium products to recycle as lubricating oil stock; and (3) residuum, which
is the nonvolatile portion of the feedstock and contains all the carbon, wear metals,
degraded additives, and most of the lead and oxidation products. The residuum might
be suitable as an asphalt additive for road paving.
During this step, other contaminates such as ethylene glycol (antifreeze; ASTM
D2982) that has leaked into the lubricating oil or has been disposed of incorrectly
and included in the used lubricating oil are also removed. Ethylene glycol (boil-
ing point: 197°C, 355°F) boils sufciently lower than lubricating oil (boi ...