With increasing prices of the base raw
material, i.e. crude oil, recycling of waste
oil has become an economically attractive
proposition, in as much as it is a way of
minimising environmental hazards while
also helping conserve a scarce nonrenewable
resource.
The recycling of used lubricants has been
practiced to various degrees since the
1930s 64 and particularly during the Second
World War, when the scarcity of adequate
supplies of crude oil encouraged the reuse
of all types of materials, including
lubricants. In the earlier part of the 20th
century, lubricating oils contained few or no
additives at all. Recycling these oils usually
involved some basic and simple processes
which were a combination of heating to
remove volatile components; settling to
separate water, dirt, and sludge; and
centrifuging or filtering to remove most of
the remaining insoluble contaminants.
While this limited processing could not
bring recycled oils to match the original oil
quality, technological improvements now
enable recycled oils to be at par with virgin
oils in quality.
In recent years environmental
considerations regarding the conservation
of resources have further boosted interest
in recycling. Recent developments, in
particular the emphasis on waste recovery,
have led to further renewed interest in recycling used oils. In some developed countries up
to 50% of the countries’ need for lubricating oil is met through recycled oils. There are
different methods used by different countries for recycling used oils. It has been established
that almost 85 to 90% of dehydrated waste oils can be converted into useful products,
including base oils for further processing into lubricating oils or fuel. The examples in Table