The filtration of electrified solid particles in a fixed bed of sand was ca
rried out. The particles were electrified by impacting them against an obst
acle. This was done in a controlled way, so that several levels of charging
could be attained. The collection of the charged particles took place in a
cylindrical filter 0.15 m in diameter and three bed heights (0.01, 0.02, a
nd 0.04 m) tall. Phosphatic concentrate particles with a mean diameter of 5
.2 mu m were utilized as the test powder. The results have shown that the p
resence of electrostatic charges can alter significantly the filtering beha
vior of the granular bed. The measured penetration of particles through the
bed in the initial stages of the filtration was compared to the theoretica
l prediction, and the discrepancies suggest that the effect of electrostati
c charges is stronger in the larger particles (>3 mu m). As filtration prog
resses, the effect of charges is strongly felt, as the increase in the pres
sure drop caused by the deposited particles becomes less pronounced with in
creasing particle charge. In some cases, an increase in the penetration of
particles is observed The relation between particle charge and filtering be
havior was not linear: the bed penetration increased, passed through a maxi
mum, and then decreased with increasing particle charge, and the pressure d
rop behaved accordingly. The measurement of charge distribution between the
particles revealed the presence of both positively and negatively charged
particles, with the predominance of the former, which resulted in a positiv
e mean charge for the aerosol. This distribution was affected by the level
of charging and seems to be responsible for the nonlinear behavior of the f
ilter.