Whole-body vibration in open pit mining - a short review

The main objective of this study was to synthesize scientific knowledge in order to characterize Whole Body Vibration (WBV) in open pit mining: sources, measurements methodologies and main effects on health. A review based on PRISMA Statement was done. Inclusion criteria were research on WBV in mining, published after 1990 and written in English. Thirty-three studies were included in the review. Rock drills, shovels and dumpers are strongly present in this industry. They are potential sources of workers exposure to WBV. All bibliography followed methodological recommendations of ISO 2631-1:1997. For WBV characterization routine works, individual tasks, occurrence records, pavement features, were topics considered. Dumper is the equipment that can be the more dangerous; it has the highest Root Mean Square (RMS) acceleration values. Back pain is the main complaint in workers due to WBV exposure. All identified studies were screened initially by title and abstract, and then more carefully in full text. 3 RESULTS AND DISCUSSION 3.1 Research results Literature search has produced 607 potentially relevant papers. Following screening process steps shown in Figure 1. Thirty-three articles were included in the review. Most of them were discarded due to violating the inclusion criteria, although many duplicates were also excluded. Figure 1. Flow diagram of studies selected for review. 3.2 Sources of vibration in mining Classes of equipment and their open pit mining operations (WBV producers) were studied (Table 1). Table 1. Equipment and operations associated with WBV. Machine Activity Rock drill Positioning Drilling Travelling Shovel Trenching/excavating Swinging and loading Travelling Dumper Travelling Loaded by shovel Unloading Kunimatsu and Pathak (2012) 3.2. 1 Rock drills Rock drills are, according to several authors, the equipments that produce lower Root Mean Squared (RMS) acceleration values over the occupational exposure. Howard, Sesek et al. (2009) reached an acceleration of 0,30 m·s -2 and Van Niekerk, Heyns et al. (2000) 0,16 m·s -2 on vertical axis (zz). According to these authors, at this workplace, the operator will be safeguarded from the risk of exposure to WBV. These studies were the only ones to analyze WBV in rock drills. 3.2. 2 Shovels Due to its flexibility, low-cost operations, maintainability and multifaceted operating capability, shovels are widely used in surface mines (Frimpong, Galecki et al. 2011). The studies aiming the characterization of WBV exposure in shovels, in open pit mining, found very different values for RMS. Some studies point to WBV values below 0.5 m.s -2 (Howard, Sesek et al. 2009; Aye & Heyns 2011; Dentoni & Massacci 2013). However, authors like Vanerkar, Kulkarni et al. (2008) call attention to the risk conditions that may be subject these workers, with WBV values reaching 2.3 m.s -2 . The same happens with the predominant axis, there is no a clear definition. The vertical (zz) and the longitudinal (xx) are presented as the main axis according Aye & Heyns (2011) and Dentoni & Massacci (2013). Thus, the discrepant characterization of exposure to WBV in these equipments is notorious. This is probably due to the multiple operations carried by shovel, which lead to different situations. 3.2.3 Dumpers Dumpers are strong vehicles widely used in open pit mining environments to transport large quantities of rock to crushing plants or dump locations. Their capacity range is from 7 to 350 tonnes (Mandal & Srivastava 2010; Eger, Stevenson et al. 2011). The majority of studies analyzed (Van Niekerk, Heyns et al. 2000; Kumar 2004; Eger, Stevenson et al. 2008a; Howard, Sesek et al. 2009; Mandal & Srivastava 2010; Smets, Eger et al. 2010) assigns to these machines considerable vibration values, above 0.5 m.s -2 . The predominant axis is the vertical (zz). The dominant frequencies are set below 4 Hz. 3.2. 4 Synthesis Table 2 shows the analyzed studies towards the characterization of WBV exposure in rock drills, shovels and dumpers in open pit mines. It is focused the RMS acceleration value, main axis and dominant frequencies. In open pit mines, in terms of WBV exposure were highlighted by its relevance, rock drills, shovels and dumpers (Howard, Sesek et al. 2009). Rock drill workers had the lowest exposition to WBV (only office workers are below). They are followed by the Shovels and Dumpers operators by increasing degree of risk. This ranking is consistent with the values collected in this review. Thus the dumper will be the workplace targeted for priority intervention. Table 2. Summary of studies characterizing exposure to WBV in rock drilling, shovel and dumper in open pit mining. Machine Authors (year) RMS [m.s] Main axis Dominant frequencies