Indirectly acting rotary drums make it possible to have drying or cooling without direct contact with the hot drying gas or cold cooling air. This means that bulk materials with a fine particle size can be effectively brought to high temperatures and very hot and fine solids can be cooled down by means of heat recovery.
The heat recovery in these units contributes significantly to long-term cost-effectiveness and sustainably protecting the environment. This not only conserves natural resources, but also lowers productions costs because of the energy saved. Moreover, the process can also be performed in a reduced-oxygen atmosphere.