The iron ore mining industry makes use of various processes that result in the release of airborne dust into
the surrounding atmosphere where workers are exposed, to produce a final product. The deposition in the
lung and toxicological influences of airborne dust can be determined by their physical- and chemical
characteristics. The Occupational Health and Safety Act (OHSA) regulations for hazardous chemical
substances have no current system of how the physical- and chemical properties of particulates originating
from specific areas will influence a worker‘s exposure and health, especially for ultrafine particles (UFP). It is
therefore imperative to characterise airborne dust containing micrometer and UFP size particles originating
from specific areas to determine if there are physical- and chemical characteristics that may or may not
have an influence on the workers‘ health.
Aim: This pilot study is aimed at the physical- and chemical characterisation of the airborne iron ore dust
generated at the process areas of an opencast iron ore mine. Method: Sampled areas included the
Primary-secondary crusher, Tertiary crusher, Quaternary crusher and Sifting house. Gravimetric sampling
was conducted through the use of static inhalable- and respirable samplers in conjunction with optical- and
condensation particle counters that were placed near airborne dust- emitting sources. Physical- and
chemical characterisation was done with the use of scanning electron microscopy (SEM) and energy
dispersive X-ray spectroscopy (EDS). Results: The results found in the study indicate high mass
concentration levels of inhalable dust at all four process areas, as well as high levels of respirable dust
found at the primary- secondary crusher area. Particle size distribution optical particle counter (OPC) results
indicate that the majority of particles at all four process areas are in the region of 0.3 μm in size.
Condensation particle counter (CPC) results integrated with OPC results indicate that at the primarysecondary
and Tertiary crushers the majority of particles are found to be in the size fraction <0.3 μm. SEM
analysis indicates that particle agglomeration largely occurs in the airborne iron ore dust. Particle splinters
originating from larger particle collisions and breakages are present in the airborne dust. EDS analysis
indicates that the elemental majority of the airborne iron ore dust consists of iron, oxygen, carbon,
aluminium, silicon, potassium and calcium. The elemental percentages differ from each process area where
an increase in iron and decrease in impurities can be seen as the ore moves through the beneficiation
process from the Primary-secondary crusher to the Sifting house. Conclusion: The results obtained from
the physical- and chemical properties of the airborne iron ore dust indicate high risk of over-exposure to the
respiratory system, as well as possible ultrafine particle systemic exposure, that may overwhelm the
physiological defense mechanisms of the human body and lead to reactive oxygen species (ROS) formation
and the development of pathologies such as siderosis, silicasiderosis and lung cancer. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2014
| Identifer | oai:union.ndltd.org:NWUBOLOKA1/oai:dspace.nwu.ac.za:10394/10821 |
| Date | January 2013 |
| Creators | Badenhorst, Rehan |
| Source Sets | North-West University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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