Abstract: A vertical cylinder reactor which comprises a plurality of vertically coupled cylindrical modules. An upper end of the reactor, a first module, employs a spraying device for subdividing a liquid reactant into a plurality of small droplets and a toroidal ring for introducing a gas reactant around the liquid phase droplets. A second module connected downstream to the first is provided with a gas inlet jacket for introducing a heating and/or drying gas into the reactor. Connected to the second module is a third module which has a tangential gas inlet for introducing a gas tangentially into the reactor. Finally the reactor is provided with a conical bottom and an outlet conduit for removing gas containing fine solid particles.

Abstract: The process of the invention is carried out in gaseous phase by the action of ammonia on the aqueous solutions of iron salts in an appropriate reacting vessels.