1774 E. Long II. iii. 560 What is drawn in the refining process, and afterwards sold to the distillers, must be very much impoverished.
1839 A. Ure 608 The gold produced by the refining process with lead, is free from copper and lead.
1948 6 Sept. 37/1 (advt.) The residues left over from this modern lube oil refining process.
2003 16 Oct. i. 20/5 GTL..is claimed to be significantly cleaner than traditional petrol or diesel but the refining process produces considerable carbon dioxide emissions.