Used engine oil is exactly what its name implies, any petroleum-based or synthetic oil that has been used. Oil keeps our cars, lawnmowers, and many other machines running smoothly. However, during normal use, impurities such as dirt, metal scrapings, water, or chemicals, can
get mixed in with the oil, so that in time, the oil no longer performs well. Eventually, this used oil must be replaced with virgin or re-refined oil to do the job correctly. Used engine oil is a valuable resource. However, not all used oil is disposed of appropriately. Used oil collectors take used motor oil from collection tanks at sites such as landfills, waste transfer stations and work depots. The used oil may then undergo some pre-treatment before it is recycled or is sold to a specialised used oil recycler.
Pre-treatment of used oil involves removing any excess water. This process is known as dewatering. One way of doing this is by pouring the used oil into large settling tanks where theoil and water separate. Depending on the final product, used oil can go through various
- recycling stages, including:
- filtering the oil to remove any solids present in the oil
- demineralisation to remove inorganic material and certain additives
- propane de-asphalting to remove the heavier bituminous fractions
- distillation to physically separate the components of lubricating oil by boiling range
- solvent extraction to dissolve and remove undesirable compounds, and
- hydrofinishing to improve physical properties of a re-refined base-oil.
Engine oil has various uses such as:
Industrial burner oil
Mould oil to help release products from their moulds (e.g. pressed metal products, concrete)
Bitumen based products
An additive in manufactured products, and
Re-refined base oil for use as a lubricant, hydraulic or transformer oil.
Raw materials for the refining and petrochemical industries