Abstract: A process for preparing iron-based catalysts for the synthesis of ammonia by melting of magnetite along with metal oxides as promoters, subsequent cooling of the molten mass and reduction thereof to the desired size, wherein the abovesaid cooling occurs at a rate higher than 25.degree. C./min., preferably ranging from 100.degree. C. to 1600.degree. C./min., at a temperature ranging from 1700.degree. C. to 700.degree. C.The present invention relates to a process for preparing iron-based catalysts having a high activity in the ammonia synthesis, and to the catalyst so obtained.

Abstract: Process for granulating chemical products, according to which process, recycled granules are conveyed to a rotary drum through an end thereof and are lifted by blades protruding from the drum inner surface, thus falling onto an inner fixed structure, which cause the forming of a vertical curtain of granules, onto which curtain a solution containing the product to be granulated is sprayed; the product solidifies on the granules, which granules, after subsequent falls, are coated with a plurality of layers of solid product before leaving the drum through the other end. The process is characterized in that said inner fixed structure is conveying the falling granules in at least two vertical curtains parallel to each other and to the drum axis, while a portion of the granules, on the side of the downward movement of the drum, directly falls, without passing through a vertical curtain, onto a fixed baffle, which is arranged substantially in the lower half of the drum, on the side of the downward movement.