Abstract: Pigment grade Fe.sub.2 O.sub.3 is prepared from ferrous sulphate by a roasting process. The ferrous sulphate, partly dehydrated and granulated, is partially converted to the oxide by roasting. After elimination of soluble constituents by washing with water, the oxide is subjected to pigmentary calcination and then crushed and optionally micronized. This process makes it possible to prepare red pigments of excellent quality characterized particularly by pure tints ranging from orange-red to purplish-red. The oil absorptions are especially low. Low toxic impurity concentrations permit the use of these pigments in foodstuffs.
Type:
Grant
Filed:
October 2, 1979
Date of Patent:
April 14, 1981
Assignee:
Thann et Mulhouse, Corp.
Inventors:
Pierre Portes, Jean M. Trautmann, Daniel Hoffner