Process for melamine purification
US11059793B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 21, 2017 |
| Grant date | Jul 13, 2021 |
| Priority date | — |
| Expiry date | Jun 21, 2037 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D251/60
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A process for the purification of a melamine melt (5) containing melamine and by-products, comprising the steps of: (a1) quenching of said melamine melt; (a2) decomposition of by-products with alkali, providing an alkaline aqueous solution of melamine (26); (b) stripping of said alkaline aqueous solution of melamine (26); (c) crystallization of melamine with a first alkali-containing solution (6b) and separation of solid melamine (7) from a mother liquor (8); (d) treatment of said mother liquor, providing a waste water stream (11) containing carbonates; (e) decomposition of at least part of the carbonates contained in said waste water stream (11) into carbon dioxide and alkali, providing a second alkali-containing aqueous solution (30); (f) recycle of at least part of said alkali-containing aqueous solution (30) to at least one of said steps (a1), (a2) and (c).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.