U.S. 8,206,681 B2
Rockwood Italia SpA has been granted a patent for a process for producing red iron oxide comprised of providing a ferrous chloride feedstock, precipitating high surface area lepidocrocite seeds having a BET surface area of greater than 175 m2/g by mixing the ferrous chloride feedstock with an alkali and oxidizing the obtained mixture and growing the lepidocrocite seeds at an overall acidic pH, wherein the growing of the lepidocrocite seeds is carried out by adding further ferrous chloride feedstock and alkali to the mixture, whereby the lepidocrocite converts into hematite.
Source:
http://www.coatingsworld.com/issues/2013-03/view_patents/rockwood-patents-process-to-produce-red-iron-oxide/
