Primary blasting in a limestone quarry: physicochemical characterization of the dust clouds

Abstract

Airborne dust generated by primary blasting was collected in Taffs Well Quarry, just north of Cardiff, Wales. Collections of airborne particulate matter were also made in the nearby village of Morganstown at the same time as the blasting collections. The explosions were recorded on a motor-driven camera and a digital video camera. These images show that the dust clouds generated by the explosions consist of three distinct components; a reddish-grey dust cloud, followed by a light grey dust cloud, and finally a pale grey cloud that stayed near the blast face. It is believed that the reddish-grey cloud was composed mostly of mineral grains, as evidenced by the chiefly red colour of the dolomitic limestone rock in the quarry. The whiter clouds contained more explosive combustion particles (diesel soot). The samples were studied by analytical scanning electron microscopy, very high-resolution field emission scanning electron microscopy, and image analysis. The two different components (minerals and diesel soot) can be readily seen under high-resolution electron microscopy. Any consideration of the possible adverse health effects or nuisance value of this dust needs to consider both of these components. A size distribution of the quarry particles shows that soot particles dominate the assemblage under 2 mm, whereas the mineral grains are more abundant over 2 mm. This contrasts with the Morganstown particle sizes, where the two components show similar size distributions. The determination of the mineralogy of the quarry dust and Morganstown particles has shown highly complex and heterogeneous mixtures, though some distribution patterns are emerging. It is concluded that much of the dust in Morganstown probably originated from sources other than the quarry, such as other local industries, roads and construction sites.

Dust barriers in open pit blasts. Multiphase Computational Fluid Dynamics (CFD) simulations

“…As is shown by Almeida et al [10] and Jones et al [11] the particulated material thrown to the air by a blast has two main sources. First, rocks pulverized by the several phenomena that take www.witpress.com, ISSN 1743-3541 (on-line) place in the blast (shock wave, high pressure gases or dynamic breaking mechanisms, etc.)…”

A CFD Lagrangian particle model to analyze the dust dispersion problem in quarries blasts

“…Another important parameter that has to be defined is the particle size distribution of the material that forms the dust cloud. As is shown by Almeida [3] et al and Jones et al [4] the particulated material thrown to the air by a blast has two main sources. First, rock pulverized by the several phenomena that take place in the blast (shock wave, high pressure gases or dynamic breaking mechanisms, etc.)…”

CFD simulation of blasting dust for the design of physical barriers

“…Almeida et al (2002) have analysed samples in limestone and granite quarries, Jones et al (2003) have carried out studies in a Wales limestone quarry and finally Appleton et al (2006) have done studies in Derbyshire, UK. In Table 1, the granulometric distribution for seven particle families used in the models is shown.…”

“…In this case, a dispersed phase, made up of seven families of particle size, with mass distributions obtained by Almeida et al (2002) and Jones et al (2003) has been used.…”