To collect the very fine particles a new technology is used in the field of "nano" spray drying. The reason is that common cyclone technology depends on the particle mass; particles smaller than 2 μm can't be separated and instead exit the system along with the exhaust gas.
The electrostatic particle collector charges the dry particles' surface and deflects them with an electrical field. To produce the electrical field, a high voltage (16 kV) is applied to a round collector tube. The electrical field builds up between the inner wall of the collector tube and the tips of a grounded star electrode. To have a low level of energy in the system the current is very low.
After getting deflected the particles stay at the inner wall of the particle collector tube and are completely uncharged. This separation method works fine for all kinds of materials.
The efficiency of the electrostatic particle collector is very high: 99% of all particles that enter the system are collected.