Dust particles in the atmosphere are a key cause of nuisance, health and other
environmental problems. The mining sector is a major source of airborne particulate
matter caused by operations like terrain clearing, drilling, blasting, tipping and loading
and the passage of vehicles on unpaved roads. The nuisance effect of airborne dust
can be measured by using dust buckets and/or directional dust deposition gauges. Dust
buckets are used to determine vertical dust deposition rates and directional dust
deposition gauges are used to determine the direction of the sources.
Traditionally the measurement of the vertical flux of dust, or dust deposition has been
used as to indicate the nuisance caused by coarse suspended particulate matter.
Several countries have produced standards for permissible dust deposition rates.
Although alternative deposition measurement methods have been proposed, ASTM
D1739 has remained the method most often used in the South African mining and
industrial sectors to measure dust deposition. In addition, a number of non-standard
directional dust deposition gauges have been used.
SANS 1929:2005 (South African National Standards, 2005) prescribes the use of ASTM
D1739:98 for measuring dust deposition. However, for historical reasons the previous
version, ASTM D1739:70 (re-approved as ASTM D1739:82) is still widely used and in
the recently promulgated South African Dust Management regulations the use of this
version is prescribed. In order to determine the difference in the results obtained by the
two versions, ASTM D1739:82 and ASTM D1739:98 were used to measure dust
deposition levels arising from a coal mining operation in the Mpumalanga Province and
a gold mining operation in North-West Province.
In order to determine whether a correlation exists between vertical dust flux (dust
deposition) and horizontal dust flux, standard directional horizontal dust flux gauges
according to BS 1747 part 5 were also set up at both sites. The measurement of dust
deposition using three dust deposition gauges (i.e. ASTM D1739:82, ASTM D1739:98
and BS 1747 part 5, directional dust deposition gauges) was undertaken monthly over a
period of fourteen (14) months at the two sites.
The findings of the study indicate that the dust deposition rates for an opencast coal
mine are generally higher than the dust deposition rates for an underground gold mine.
ASTM D1739:98 was shown to be a more efficient dust deposition collection method
than ASTM D1739:82, with the ratio between the mean values slightly more than 2. The
addition of water to the dust bucket does not make a statistically significant difference to
retention of dust in the bucket. There is a weak correlation between results for the
vertical dust gauges and horizontal dust flux.
It is recommended that the South African mining sector continue dust deposition
monitoring and reporting using the more recent version of ASTM D1739, as high
deposition levels may indicate a potential health impact from PM10 thoracic dust.
Dissertation (MEng)--University of Pretoria, 2014.