Particle size distribution: A key factor in estimating powder dustiness

Abstract

A wide variety of raw materials, involving more than 20 samples of quartzes, feldspars, nephelines, carbonates, dolomites, sands, zircons, and alumina, were selected and characterised. Dustiness, i.e., a materials' tendency to generate dust on handling, was determined using the continuous drop method. These raw materials were selected to encompass a wide range of particle sizes (1.6-294 µm) and true densities (2650-4680 kg/m). The dustiness of the raw materials, i.e., their tendency to generate dust on handling, was determined using the continuous drop method. The influence of some key material parameters (particle size distribution, flowability, and specific surface area) on dustiness was assessed. In this regard, dustiness was found to be significantly affected by particle size distribution. Data analysis enabled development of a model for predicting the dustiness of the studied materials, assuming that dustiness depended on the particle fraction susceptible to emission and on the bulk material's susceptibility to release these particles. On the one hand, the developed model allows the dustiness mechanisms to be better understood. In this regard, it may be noted that relative emission increased with mean particle size. However, this did not necessarily imply that dustiness did, because dustiness also depended on the fraction of particles susceptible to be emitted. On the other hand, the developed model enables dustiness to be estimated using just the particle size distribution data. The quality of the fits was quite good and the fact that only particle size distribution data are needed facilitates industrial application, since these data are usually known by raw materials managers, thus making additional tests unnecessary. This model may therefore be deemed a key tool in drawing up efficient preventive and/or corrective measures to reduce dust emissions during bulk powder processing, both inside and outside industrial facilities. It is recommended, however, to use the developed model only if particle size, true density, moisture content, and shape lie within the studied ranges.

Occupational Exposure and Environmental Release: The Case Study of Pouring TiO2 and Filler Materials for Paint Production

“…Here it seems that near spherical materials with d 50 > 20 µm have higher potential to release respirable particles (e.g., clay OpTiMat, microspheres) when compared to materials with smaller particle diameters (e.g., dolomite, kaolinite, calcined clay, and calcite). Similar observations were previously reported for micron-sized and nanoscale powders [35,37,[70][71][72][73]. This is probably due to the weaker cohesive forces and consequently material dustiness is higher and particles with small diameters are more probable to be released.…”

“…The characterization data demonstrate a considerable range in BET-SSA values (e.g., dolomite and TiO 2 with 3.2 and 13 m 2 g −1 , respectively), particle grain sizes (0.25 to 30 µm), bulk densities (0.16-1.09 g cm −3 ), and particle shapes (e.g., plate talc, plate clays, rod calcite, and spherical TiO 2 and dolomite). Therefore, establishing a general relationship between emission patterns and materials physicochemical characteristics might be challenging [70][71][72][73].…”

On the Relationship between Exposure to Particles and Dustiness during Handling of Powders in Industrial Settings

“…According to the literature, significant correlations may be observed between particle SSA and dustiness when comparing different quartzes (López-Lilao et al, 2016) and different kaolin samples (López-Lilao et al, 2015). Previous works (López Lilao et al, 2017) have shown that, for approximately spherical and dry materials, coarser mean diameters present a higher potential for release of fine particles. Thus, dustiness depends on the amount of fine particles and the material's ability to release such fine particles.…”

Health risk assessment from exposure to particles during packing in working environments

“…Particle mass was calculated by using mobility particle diameter and effective density as in Koivisto et al (2012b). Particle density during packing was assumed to be 2.55 g cm -3 as it is the materials' mean density (López Lilao et al, 2017) described by the provider, and 1.5 g cm -3 during background (Martins et al, 2015). The regional inhalation dose rate, calculated for head airways, tracheobronchial and alveolar regions, was obtained by applying WA particle size concentrations to simplified deposition fraction probability equations for the ICRP human respiratory tract model (ICRP, 2011) as described by Hinds (1999).…”