Used Oil re refining

1. Notes on Used Oil re refining
A Lubricant Industry compilation
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Notes on
Used Oil Re refining
(With an extract from an API presentation
Recycling Used Engine Oil by Re-refining)
A Lubricant Industry compilation
M Hussam Adeni
Chemical Engineer by education
Lubricant Specialist by
 Certification - MLA 1 – www.icml.com, Lube Council
 Experience – Castrol, BPCastrol
 Membership – www.stle.org
GHG mitigation and Fuel Conservation Evangelist by Philosophy

2. Notes on Used re refined Oil
Re-refining is a process used to refurbish used oil and return it to a high-quality base oil. In the United
States, approximately 40 percent of used oil is captured and recycled in some manner, while 60 percent is
lost. Nearly 14 percent of the captured and recycled oil is re-refined.
An expression commonly used to explain the gradual process of oil contamination, additive depletion and
viscosity increase (thickening) is that the oil is "breaking down" and may no longer be able to maintain its
lubricating qualities. Even though the additive package has been depleted, much of the base oil is still in
relatively good condition. The re-refining of used oils is a process of repeating some or all of the five basic
refinery processes to return the base oil to a usable condition or state.
Re-refiners use various processes to remove contaminants, water, spent additives and any of the original
remaining additives from the used oil.
 The result is the reclamation of approximately 75 to 80 percent of the original base stock.
 A further process of refining and blending is then carried out to produce finished products.
Some re-refined oil is proving to be as good as, if not better than, virgin base oil. It is very dependent upon
the re-refining technology and the source of the used oil
Keep in mind that used oils that have been "reclaimed," "reprocessed" or "recycled" are likely of inferior
quality and may have only passed through a settling and/or filtering process.
There are broadly two methods to recover base oil from used lubricating oils.
1. Re claimation - Acid clay treatment followed by distillation.
Due to environmental concerns (disposal of acid sludge) this is banned, in many countries
2. Re refining - Physical separation followed by distillation
a. A popular process is called – Wiped Film Evaporator (WFI) this is followed by Vacuum
Distillation

3. Acid Clay Treatment
In the acid clay process, used oil is typically filtered and then heated to remove debris, solid particles and
water. It is then mixed with Sulphuric acid which extracts metal salts, acids, aromatics, asphaltenes and
other impurities. This forms a by-product of acidic sludge that settles out of the oil. The remaining slightly
acidic oil is mixed with active fuller’s earth (clay) to remove mercaptans and other contaminants and to
improve colour. This process requires approximately 0.4 lb of clay per gallon of oil. After clay is filtered
from the oil, the final steps are neutralization and distillation of the oil.
Acid clay treatment was the predominant technology in the past.
Today, in many countries and states, the acid clay process is banned due to the hazardous waste of the
acidic clay from the process; the disposal of this acid sludge is a nightmare.
Process comparison
A comparison of the various technologies available for Used Oil re refining is given below:
Factors for
evaluation
Thin film
evaporation
process
Vacuum
distillation with
clay treatment
process
Acid clay
process
Direct clay
treatment
process
Distillation followed by
solvent extraction
Lube yield 65 - 75% 65 - 75% 60 - 62% 54 - 60% 65 - 75%
Utilities
consumption High High Low Low High
Energy
consumption Low Low Low Low Low
Process
Semi-continuous
/ continuous Batch / continuous Batch Batch Continuous
Hazardous
chemicals None None Acid None None
Waste streams
Residue 10 - 12% 10 - 12% None None 12 - 15%
Acid sludge None None High None None
Spent clay 2.5 - 6% 2.5 - 6% 8 - 10% 2.5 - 306% None
Heating Indirect Indirect Direct Direct Indirect

4. Re refining process
Source: Sequela Rerefining project
Used Oil pick up – Sourcing
This is most critical step, if the collection is from used oil segregated at the user level the end result
is a good source and yields a good product.
Typically all Used oils are categorised and stored separately. Used Engine Oils is stored separately
and the used Gear and Transmission Oils, Hydraulic Oils and other grades are stored separately. Other oils
like Metal working Oils and Emulsions are also stored separately.
Over the past, in India, used oils have been treated as thrash. As a result it was stored in old (top
cut away) oil barrels/drums and dumped in the open yard, allowing access to dirt, rain water and
invariably, other waste is also dumped in the same oil barrels/drums. Units having automobile workshops
often use Diesel or other solvents for cleaning and degreasing, this too is dumped in the same oils
barrels/drums.
While pre-screening / pre treatment, at the Used Oil re-refining plant can deal with most of the
contaminants and even free water, it is the emulsified oils that generally cause some difficulty. The net
result of all this is, a lower of yield re-refined oil, per se.

5. Analytical Testing to ensure Quality
Oil from a wide variety of sources may contain chemical or physical contaminants that are hazardous or
prevent that oil from being used in the re-refining process. Constant testing ensures that our feed stocks
are capable of producing the highest quality end products. Result: premium products and environmentally
correct recycling.
Dehydration to remove water
Water finds its way into many used oil storage areas, so it’s the first thing we remove, using a process of
evaporation. The water is collected, treated to be chemically and biologically safe and then discharged.
Distillation 1 – Light end recovery
Lightweight chemicals are extracted for reuse. With the water removed, the used oil goes to tall recovery
towers where glycol and light fuels are separated and collected. By products: glycol is eventually
reprocessed as a finished automotive grade product.
Distillation 2 – Fuel stripping and recovery
Heavier fuels are removed for industrial use. The used oil is now subjected to heat and vacuum processes
which extract middle weight oils. By products: fuel for industrial heating.
Distillation – Vacuum Distillation - Wiped Film Evaporator
Heavy materials are reclaimed for multiple uses. The heaviest impurities are removed in a complex series
of processes. The used oil is actually vaporized in an extreme vacuum and then condensed. Different
materials are then separated from the oil. By products: heavy oil for industrial use, such as asphalt
extenders, which are made from the heaviest residual material.
Hydro treatment
The remaining oil is treated with hydrogen to remove sulphur, nitrogen, chlorine, heavy metals and other
impurities. This step also corrects any issues with odour, colour and corrosion performance. The purified
oil is then separated by weight – cleaner than the day it was first refined and ready to return to the
marketplace.
Used re refined Plant Manufacturers
There are a number of Used Oil Re fining Plant manufacturers with units set up and operating in India, the
Middle East and Africa. Information on the same can be provided on request.

6. Extract from an API
presentation
Recycling Used Engine Oil
by Re-refining

7. Recycling Used Engine Oil by Re-refining
Presented at
California 2005 Used Oil/HHW Conference
“Building Hope for Healthy Communities, One Action at a Time”
Bahia Resort Hotel
San Diego, California
April 28, 2005 - Dennis L Bachelder

8. What is a Re-refined Base Oil?
It is used motor oil that undergoes
an extensive refining process to
remove contaminants, distill the
used oil and reform the oil
molecules to produce new base oils
that have the same performance
characteristics as virgin base oils
made from crude oil.
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9. Re-refined vs. Recycled Base Oils
Recycled base oils using the acid-clay and the
clay filtration processes are not the same as re-
refined base oils.
Typical concerns:
Do not get typical base oil viscosity
fractions/grades
Recycled base oils may not have the same
performance and oxidation stability
Quality may be very variable depending on
feedstock
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10. Typical Re-refining Process
6/9/2005 4Courtesy Safety Kleen
Used Engine Oil

11. Typical Distillation
Recycling & Re-refining Used Lubricating Oils; May 1993
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12. Re-refined Base Oil Quality
Used Oil
Feedstock
Vacuum
Distillation
Feedstock
Hydrotreat
Feedstock
Light
Hydrotreat
Feedstock
Heavy
Final Base Oil
Light
Final Base Oil
Heavy
Water (% Vol) 20 <1 <1 <1 -- --
Flash Point (°C) >100 215 154 193 182 210
Vis. @ 100°F N/A 375 85 230 90 240
Acid No. (mg/KOH) 2.4 4.0 1.5 0.5 0.01 0.01
Chlorine, ppm 2800 2700 1150 800 <50 <50
Sulfur, ppm 4000 4000 3000 3000 600 600
Zinc, ppm 550 550 <1 <1 <1 <1
Lead, ppm 70 70 <1 <1 <1 <1
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Recycling & Re-refining Used Lubricating Oils; May 1993

13. Product Quality
Paraffinic base oils which meet or exceed
customer, industry and government standards
Meets API Group I and Group II Specifications
Capable of being formulated to provide lubricating
oils meeting newest standards
API SM / ILSAC GF-4
API CI-4 Plus
GM Dexron IIIG Automatic Transmission Fluid
Military Specification (e.g. Mil-PRF-2104G)
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14. Re-refined base oil Relative Cost
Re-refined base oils are typically comparable in
cost to virgin base oils
When there is a surplus of used oil there may be
a slight cost advantage for re-refined base oils
due to lower feedstock costs relative to crude oil
When higher VI used oils are available as
feedstock it is possible to make high quality API
Group II base oils
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15. Re-refined Base Oil Cost Pressures
Competition for used oil feedstock
Used as a Marine Fuel increases the price of the
feedstock
Collection Logistics
Must have a source of used oil from Quick Lubes
and Industrial Accounts within a reasonable
distance
Used oil must be relatively good and free of
excessive contamination (e.g. solvents, coolant, etc)
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16. API Service Category Certification
Re-refined Base oils,when formulated into an
engine oil, are capable of being Certified and
Licensed by the API Engine Oil Licensing and
Certification System (EOLCS).
All API Licensed products meet the performance
requirements set by the manufacturer for their
engines.
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17. API EOLCS Quality Trademarks
Re-refined Base oils, when formulated into an engine oil, are
capable of being Certified and Licensed by the API Engine Oil
Licensing and Certification System (EOLCS).
Only Licensed Engine Oils Carry the API Quality Trademarks for
easy consumer identification.
All API Licensed products meet the performance requirements set
by the engine manufacturers.
API Donut
Gasoline Service Category
API Donut
Diesel Service Category
ILSAC Starburst® ® ®
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18. Re-refined Engine Oil Availability
Engine Oils formulated with Re-refined base oils are in marketplace
Primarily Drum and Small Package
Some Engine Oils Indicate that re-refined base oils are used
Safety-Kleen America’s Choice
Chevron ECO
Evergreen Motor Oil
76 Firebird
Rosemead SOAR DLX
Lyondell Enviroil
Hick’s Oil Natural Choice
Others Do Not Indicate they use Re-refined oil
Concerned about public perceptions
Blend re-refined base oil with virgin base oil
Distribution
Most distribution through Commercial and Retail Distributors
Some Distribution through retail outlets (e.g. Auto Zone, Pep Boys, etc.)
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19. Summary
Re-refined Base Oils have comparable
performance to Virgin Base Oils
API Licenses Engine Oils formulated with re-
refined base oils carrying the Newest Engine Oil
Service Categories
Re-refined base oil can meet the performance
requirements of the OEMs and the Lubrication
Industry.
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