Purpose of all granulation processes is to generate a grain with defined structure, shape,
size and composition (quality)as requested and specified.
Original material for these processes can be
● powders or fibers
● molten materials or a mixture thereof.
Drying of small moisture droplets on the surface of already existing granules in fluid bed
units(spray granulation) becomes among all known granulation processes more and more importance.
Spray granulation and - dry can be described simplified as follows:
The primary product(paste, suspension, solution) is sprayed directly through a special nozzle into the fluidized layer.
The liquid droplets, as they are formed through spraying, hit onto an already existing granule,a germ particle, with varying penetration depth into the fluidized layer. According to different adhesive forces the droplet will cover the "germ" in a thin layer.
The solvent(most of the times water) evaporates utilizing the energy content of the fluidizationmedia, the dry matter stays on the surface of
the germ-granule. This leads to the familiar growing of the granuals in form of layers, "hulls". Statistically, based on
an identical residence time of each particle in the fluidized layer(an "ideal" vessel),
all germs will be met by the same amount of liquid and show the same growing rate.
Selection of spraying nozzles, laying down operation parameters and construction design, especially that of the air distribution plate,
are determined by the product itself, characteristic of the primary product and requirements
on the final product.
All necessary process steps can be combined for an optimum result. The final product is generated directly from pastes, suspensions or solutions. The growing of the granules always is connected to a drying process.
DAESUNG has developed for this application a special, continuous operating dryer / cooler. Its main use is in the mining,
salt, food, feed and pharmaceutical industries.
Classical process lines, combining a number of
basic processes such as evaporation, crystallization, mechanical dewatering
and thermal drying are replaced with
only one piece of equipment. Reducing the number of equipment greatly cutting back on
efforts for capital, operating and personnel costs and at the same time improves product quality.