Process for deactivating soluble metal cations in iron oxide pigments

摘要

The subject matter of this invention relates to a process for deactivating the soluble metal cations contained in iron oxide pigments comprising: A. adding, while oxidizing, an alkalizing compound to an iron oxide pigment, a slurry until the pH of the pigment slurry is greater than 9; and B. separating the iron oxide pigment from the liquid phase of the slurry. The pigments can be used as colorants for substances ingested by man and animals, and they can also be used to stabilize plastics against ultraviolet degradation.