RE-REFINING
Re-refining vs recycling waste oils
Dr Chem. Eng. Srđan Sokolović MBA, Energy and Waste and Chemicals Management Consultant, Owner of Sowa Solutions
All around the world, lubricants are present in applications where they are used to reduce the friction, heat, and wear between mechanical components that are in contact with each other. Around half of total purchased lubricants are lost during use or through leakage, with the other half of purchased lubricants ending up as waste oil.
The global waste oil market in 2021 was valued at 68.84 Bn US$ and is forecast to grow up to 98.2 Bn US$ by 2029. [1]
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‘Regeneration of waste oils’ means any recycling operation whereby base oils can be produced by refining waste oils, in particular by removing the contaminants, the oxidation products and the additives contained in such oils.
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‘Recycling’ means any recovery operation by which waste materials are reprocessed into products, materials or substances whether for the original or other purposes.
According to the UK European Union (Withdrawal) Act 2018 [3], EU Directive 2018/851 was adopted into UK law, meaning the same definitions of regeneration and recycling apply in the UK.
Generally waste oil could be used as industrial burner oil, where the used oil is dewatered, filtered and demineralised for use in industrial burners; mold oil to help release products from their molds (e.g. pressed metal products, concrete); bitumen-based products; or re-refined base oil for use as a lubricant, hydraulic or transformer oil. [4]
Figure 1: Overview of the global waste oil market [1]
Collection and treatment of waste oil in the EU is defined by Directive (EU) 2018/851 [2] of 30 May 2018 amending Directive 2008/98/EC on waste. According to the aforementioned Directive [2], waste oil is defined as:
“Any mineral or synthetic lubrication or industrial oils which have become unfit for the use for which they were originally intended, such as used combustion engine oils and gearbox oils, lubricating oils, oils for turbines and hydraulic oils.”
In the same Directive, regeneration (re-refining) of waste oil and recycling of waste are defined as follows [2]:
Recycling of waste oil The processes that are used for recycling [4] are pre-treatment (or Dewatering) or filtering & demineralisation.
Pre-treatment or Dewatering In waste oil, there is water which can be found as free phase (discrete from the other components present) or as emulsions (bound water). [4] Dewatering represents the process where free water is removed from waste oil through separation by gravity. If there is emulsion present, de-emulsifier must be used in order to free water from emulsion. Waste oil mostly free of water [4] then moves to a tank where it is heated so the remaining water will evaporate. After this, waste oil begins the process of filtering and demineralisation. [4]
Continued on page 10 LUBE MAGAZINE NO.176 AUGUST 2023 9
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