Fluidized bed spray granulation
The solution for free-flowing granulate from liquids
The fluidized bed spray granulation is a method for making free-flowing granulate from liquids. It can be used in different applications in various industries, since the product properties can be varied in many ways by setting process technical parameters and configurations. The granules are suitable for making tablets and, because of their often round shape, also for final coating.
Many industrial applications require converting liquid substances into a stable product form with exactly defined properties – whether for further processing as a solid for food products, animal feed or cleansing agents, for reducing the product volume for transport and storage reasons, for increasing stability in chemical substances or for handling thermally sensitive products such as enzymes, proteins or micro-organisms. Spray granulation in the fluidized bed permits liquids to be directly made into free-flowing granulate with specific product properties.
Liquids containing solids, such as solutions, suspensions or melts, are sprayed into a fluidized bed system. Due to the high heat exchange the aqueous or organic solutions evaporate immediately, and the solids form small particles as starter cores. These are sprayed with other liquids which in turn, after evaporation, form a hard coating around the starter core.
This step is continuously repeated in the fluidized bed so that the granulate grows layer by layer like an onion. Alternatively, a defined volume of suitable starter cores can be provided. In this option, the liquid only serves as a vehicle for the solids that are being applied.
This process variant is often used in a continuous fluidized bed system with air-classifying discharge. Through the continuous removal of the finished granules from the drying room, the amount of particles in the fluidized bed remains constant.
The granules can be very dense because they have grown in layers, and are thus resistant to abrasion. Parameters such as particle size, residual moisture and solids content can be specifically adapted in order to achieve the most varying product properties. Using spray granulation, medium-sized particles of 50 micrometers to 5 millimeters can be produced.
Properties such as ability to flow, not abrade, not flake, easily dissolve or be optimally dosed can be imparted to solids using spray granulation. The dust-free granules have a dense surface structure and high bulk density and are low hygroscopic because of their small surface. The optimal solution for converting liquid substances into a solid product form.