The influence of particle velocity on the stickiness of milk powder

Sticking of milk powder particles to the walls and ducting of spray driers is a continuing problem for milk powder manufacturing. The effects of powder velocity, angle of impact and target plate material on the stickiness of milk powders were measured using particle gun and fluid bed methods. The particle gun sticky point was taken as the point where initiation of powder stickiness occurred and was typically 10–15 °C higher than the collapse temperature observed in the fluid bed test for the same powder. This was attributed to the higher particle velocity in the particle gun resulting in contact times that were shorter than those in the fluid bed. The angle of impact and target plate material were shown to have no effect on the conditions at which the powder started to stick, but the angle of impact did affect the probability of a powder particle sticking.