Pelletizing Processes
The principle behind pelletizing processes (also known as agglomeration) is the opposite of grinding technology: it consists of gathering together or clustering fine solid particles in order to form elements of larger dimensions (spheres, bricks or even cylindrical pellets).
There are two main pelletizing methods:
- wet agglomeration: particle cohesion is obtained through the addition of a binding liquid (usually water but also organic or lignosulphonate chemical agents) and the mechanical action of a suitable device (pelletizing disc, granulator mixer, etc.). No compression is done in order to ensure the stability of the pellets;
- dry agglomeration: pellets are obtained by compression, their cohesion being guaranteed through the combined effect of the reduction in particle spacing and the increase in their contact surface. This granulation is achieved with or without a binder. The methods used to do this are briquetting-presses (iron ore, for example) or extrusion granulating presses (manufacture of solid recovered fuel).
The effeciency of the operation often depends on the mechanical stability of formed pellets (crush test, attrition test, etc.).
The main advantages of granulation are the densification of the material, which enables storage and transportation costs to be cut, providing easier handling of the material and even improving its fluidity.
CTP has various equipment of pilot-scale such as a pelletizing disc, an Eirich mixer and even a granulator press (Khal) to perform tests on mineral materials and also on plastic or organic substitute fuels.
