Keywords: Ammonium nitrate production, Nitro-Top, Ammonium nitrate quality, Fluidised bed.
The Nitro-Top process is a new process developed by Fisons for manufacturing a coated ammonium nitrate top dressing fertiliser. It has many interesting features, the principal technical innovation being that it employs a fluidised bed of fine dust particles in a unique way to coat and solidify ammonium nitrate droplets. The product is an ammonium nitrate particle of approximately the same size as a normal granular fertiliser. The combination of size distribution and granule surface characteristics are such that the material will spread like a conventional granular product.
The manufacturing process has two basic steps. The first is the production of uniformly sized droplets of anhydrous ammonium nitrate. The second is the solidification of these droplets in a cloud of coating dust in controlled conditions to give the direct production of the coated product. The manufacturing process is simple, cheap and highly efficient. Also the solidification operation removes the effluent ammonium nitrate vapour, the discharge of which in other processes, such as air prilling, causes problems.
G Drake, Fisons Ltd., UK.
43 pages, 11 figures, 3 tables, 9 refs.