Patent · US Expired

Purification of ammonium fluoride solutions

US4200622A · kind A · utility

1Cited by

5References

5Claims

0Family size

Assignee

BAYER HEALTHCARE LLC · DE

Inventors

Hans Kyri · Cologne, DE
Hans-Dietrich Lauss · Cologne, DE
Siegfried Schneider · Erlangen, DE

Key dates

Filing date	Nov 13, 1978
Grant date	Apr 29, 1980
Priority date	—
Expiry date	Nov 13, 1998

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC01C1/162
WIPO fieldMaterials, metallurgy
WIPO sectorChemistry

Abstract

In the purification of an ammonium fluoride solution containing silicic acid by adding iron (III) ions and precipitating the iron (III) ions at a pH above 8.5 and a concentration of free ammonia in the solution of more than about 1% by weight, the silicic acid being carried with the iron (III) ion precipitate, the improvement which comprises adding the iron (III) ions to the ammonium fluoride solution at a temperature below about 30.degree. C. and, before removal of the precipitate, to the solution a salt of at least one of the alkali metals, alkaline earth metals, zinc, aluminum and lead in such quantity that the solution becomes saturated with such salt.

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