Patent ID: 7604793

Claim:
A process for the production of ferric oxide precipitates having a particle size from about 0.1 to about 10 microns, the process comprising (a) obtaining an aqueous feed solution comprising iron solubilized in one member selected from the group consisting of nitric acid, sulfuric acid, and hydrochloric acid, the aqueous feed solution having a pH ranging from about 0.25 to about 2.5; and (b) subjecting the aqueous feed solution to a combination of (i) a temperature from about 100° C. to about 300° C., (ii) a seeding ratio from about 20% to about 2000%, wherein the seeding ratio is a ratio of a weight of a seed solid to a weight of an expected unseeded precipitate product, and wherein the particle size of the ferric oxide precipitates is smaller than a particle size of the ferric oxide precipitates obtained with a seeding ratio of 0%, and pressures ranging from about 40 psig to about 1300 psig to obtain ferric oxide precipitates of the particle size from about 0.1 to about 10 microns.