Dust emissions from bulk material handling are difficult to calculate. In this study, a Bulk Immission Ratio (BIR) is introduced, which results from experimental wind tunnel studies. These findings are interpreted using a model, published by Schulz et al. [1].

For the experiments dry lime stone with a bi-modal size distribution (1^st mode 4.7 µm, 2^nd mode 955 µm) is used as bulk material. 4 kg are dropped from different heights, resulting in different impact velocities. The BIR describes the ratio of the dust mass measured in the air flow to the material mass in the 1^st mode.

The model calculates the dust dispersion ratio (DR) - the ratio of dust released upon impact to dust (20 µm lime stone, 5 %wt) primarily adhering to a single dropping particle (1500 µm steel ball) - for different impact velocities and plate materials.

Similar to the modeled DR, the measured BIR first rises, followed by a plateau around 7 m•s^-1 and a further sharp increase. This paper discusses the experimental results in the context of the model predictions...