Re-refining used lubricating oil recovers valuable base oil from waste streams, reducing both cost and environmental impact. Activated bleaching earth (clay treatment) is a classic finishing step that removes colour and oxidation products to produce a marketable base oil. This guide explains its role.
The Re-refining Sequence
Used oil re-refining typically involves dehydration, distillation (to separate base oil fractions from contaminants), and a finishing step. The finishing step — historically clay treatment with activated bleaching earth, often combined with hydrofinishing in modern plants — removes residual colour, oxidation products and trace contaminants.
What Clay Treatment Removes
Activated bleaching earth adsorbs polar oxidation products, colour bodies, residual additives and breakdown compounds that survive distillation. This improves the colour, odour and oxidation stability of the recovered base oil.
Dosage and Contacting
Clay treatment dosage depends on the quality of the distilled stream and the target base-oil colour. Higher contamination requires more earth. A consistent, high-activity earth gives predictable colour reduction and limits oil retained in the spent clay.
Spent Clay Management
Spent clay from re-refining retains oil and adsorbed contaminants. Managing oil retention (using a low-retention earth) reduces base-oil losses, while spent clay is handled per local waste regulations.
Industrial Supply
Umiya Minerals offers activated bleaching earth grades suited to industrial oil finishing, supporting consistent base-oil colour in re-refining operations.
Frequently Asked Questions
What role does bleaching earth play in re-refining used oil?
It is the finishing/clay-treatment step that removes residual colour, oxidation products and trace contaminants after dehydration and distillation, improving base-oil colour, odour and stability.
How much bleaching earth is needed for clay treatment?
It depends on the contamination of the distilled stream and the target colour. More heavily degraded feed needs more earth; a high-activity product reduces the dosage required.
Is clay treatment still used in modern re-refineries?
Yes, though many modern plants combine or replace it with hydrofinishing. Clay treatment with activated bleaching earth remains common, especially in small and mid-sized re-refineries.
How is spent clay from re-refining handled?
Spent clay retains oil and adsorbed contaminants and is managed according to local waste regulations; using a low-oil-retention earth reduces base-oil losses in the spent cake.
Need Activated Bleaching Earth for Your Refinery?
Contact Umiya Minerals for product samples, technical data sheets, and bulk pricing. We supply pan-India from Bhuj, Gujarat.