Patent · US Expired

Treatment of phosphatizing waste water

US6464879B1 · kind B1 · utility

0Cited by

4References

20Claims

0Family size

Assignee

Henkel Kommanditgesellschaft auf Aktien · DE

Inventors

Jan-Willem Brouwer · Willich, DE
Peter Kuhm · Hilden, DE
Jens Vier · Monheim, DE

Key dates

Filing date	Aug 3, 2000
Grant date	Oct 15, 2002
Priority date	—
Expiry date	Aug 3, 2020

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC02F2103/16
WIPO fieldChemical engineering
WIPO sectorChemistry

Abstract

A process for treating phosphatising bath overflow and/or wash water after phosphatising, phosphatising being performed using an acid, aqueous phosphatising solution which contains from 3 to 50 g/l of phosphate ions, calculated as PO43−, from 0.2 to 3 g/l of zinc ions, optionally further metal ions and accelerator, characterised in that the accelerator is an organic molecule or molecular ion having a molecular weight of at least 80 g/mol, and that the phosphatising bath overflow and/or the wash water is subjected to ultrafiltration. The permeate from ultrafiltration is preferably separated further by means of nanofiltration or reverse osmosis. The permeate from the second separation may be recycled as wash water; the retentate may be recycled to the phosphatising bath.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.