By John Visser, METS group business development manager
DUSTINESS at the truck dump station is often misunderstood to be totally related to the ore being dumped into the dump pocket. To put this into context, there is a little known fact that is relevant - roughly one to three billion tonnes of dust is swept into the atmosphere, including the stratosphere, every year from the world’s deserts. When the wind roars across the Sahara, car wash outlets in Boston become very busy a few days later cleaning the cars that are presented.
We need to define a concept in terms of dustiness - the dust extinction moisture. This is the moisture in the ore at which dust is defined to have been extinguished, as described in the Australian standard, AS 4156.6-2000 and the DIN standard is DIN EN 15051. The DEM factor is deemed to be 10.
The original test sample mass when determining the DEM for an ore is 20kg, so at a DEM of 10, the dust collected equals 20 grams. The DEM ratio can therefore be used to estimate the dustiness at any point assuming that the ore is at its DEM point.
To assess the truck dump station, the reality is that the total dust generated during a typical day at the truck dump station arises from all of the following activities:
- Trucks dumping ore into the dump pocket
- Trucks arriving and leaving the dump station
- The movement of other vehicular traffic at the dump station, including loaders cleaning up around the area and dumping ore from the dump station
- Wind generated dust lift off from unprotected open areas around the site.
If one investigates the volumes of dust generated by each event and the total time in say a 12 hour period, some interesting facts emerge (see tables 1, 2, 3, 4 and 5).
Wind generated dust therefore, even from waste and ores that have been treated with water but the surface has been allowed to dry for roughly 10 minutes, is a major contributor to dust at the dump station (Figure 1 compares the various contributors).
The major contributors to dust at the crusher dump station are wind generated dust when the wind is blowing and both dust arising from the ore being dumped and loaders carrying out work on the dump station area. Even the haul truck movement on the dump station contributes to dust.
Therefore if dust is an issue at the truck dump station, before doing anything to prevent dustiness, carry out a scientifically structured investigation to determine all the causes and their individual contribution to the problem.
|Figure 1: The contributors to dust|
Established in 1988, Mineral Engineering Technical Services (METS) has a reputation for providing quality service to the global mining industry. METS is a Perth-based independent specialist consulting group. Professional staff are available to help on any job in Australia or overseas, whether on site or in the office. METS provides a comprehensive range of services including mineral processing, engineering design, training and specialist services.
METS core business is founded in establishing long-term relationships with clients enabling it to draw upon its historical knowledge of specific project operation to derive best possible solution outcomes.
METS is part of Midas Engineering Group comprising METS, CDMS Consulting Engineers, Midas Environmental Consulting, Norden Engineering, Wilkie Civil Engineering, Sanderson Consultants and TCT Electrical. Together the group provides a wide array of quality engineering services across the mining, oil and gas, water, power, chemicals, infrastructure, environmental, residential and commercial industries.