Citation: Kouam, J.; Songmene, V.; Bahloul, A.; Samuel, A.M. Characterization of Si and SiO 2 in Dust Emitted during Granite Polishing as a Function of Cutting Conditions. Materials 2022, 15, 3965. https://doi.org/10.3390/ ma15113965 Academic Editor: Zhenyu Zhang Received: 11 April 2022 Accepted: 24 May 2022 Published: 2 June 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). materials Article Characterization of Si and SiO 2 in Dust Emitted during Granite Polishing as a Function of Cutting Conditions Jules Kouam 1 , Victor Songmene 1, * , Ali Bahloul 2 and Agnes M. Samuel 1 1 Department of Mechanical Engineering, École de Technologie Supérieure (ÉTS), 1100 Notre-Dame Street West, Montréal, QC H3C 1K3, Canada; jules.kouam@etsmtl.ca (J.K.); agnes-marie.samuel@etsmtl.ca (A.M.S.) 2 Institut de Recherche Robert-Sauvé en Santé et Sécurité du Travail (IRSST), Montréal, QC H3A 3C2, Canada; ali.bahloul@irsst.qc.ca * Correspondence: victor.songmene@etsmtl.ca Abstract: Particles emitted during manufacturing processes such as polishing can represent a serious danger for the environment and for occupational safety. The formation mechanisms responsible for these dust emissions include chip formation, friction at the tool/workpiece and chip/tool interfaces, shearing and cutting. These mechanisms thus depend on workpiece and tool properties, as well as the polishing conditions. In the case of granite polishing, particle emissions during polishing can contain chemical compounds such as silica, which represent harmful health risks for the worker. It is therefore important to characterize the particles emitted and to search for possible interactions between the particles (size and composition) and the machining conditions in order to find ways of reducing emissions at the source. In this study, an investigation was undertaken to characterize the particles emitted during granite polishing as a function of polishing conditions, type of granite, and abrasive grit sizes used. Scanning electron microscopy (SEM) was employed for particle mor- phology characterization and particle grain size and chemical composition were evaluated using X-ray diffraction (XRD) and energy dispersive X-ray (EDX) techniques, respectively. Results show that the influence of polishing speed and feed rate on particle emission depends mainly on the granite type used, providing useful information for controlling the polishing procedure, and thereby dust emission. Keywords: granite polishing; machining conditions; crystalline silica; particle characterization; occupational safety 1. Introduction Granite is an appreciated material because of its high mechanical properties such as wear resistance and good stability. It is also useful for house and building decorations, landscaping, and urban development, etc. Polishing is the machining operation most used for shaping granite compared to drilling, grinding, and saw milling. The aim of polishing is to grind the surface of the work- piece and produce the desired finished surface quality. During this process, the abrasive used scrapes the surface and generates chips and particles, where particle emissions could be compared to the removal of very small chips. Yilmaz et al. (2013) [1] studied the effect of cutting tools on chip thickness during machining of granite and reported that a sharp cutting tool produces larger chips than a worn tool. According to Ling (1993) [2] and Li (1990) [3], after polishing, a thin ‘glossy film’ covers the surface of the granite workpiece. To learn more about it, Huang et al. (2002) [4] carried out an investigation to elucidate the appearance of this glossy film. However, no authors addressed the composition of the glossy film. In the studies of Xie (2010) [5] and Xie and Tamaki (2007) [6], it was found that depending on the machining process applied, the type of abrasive used depended on the Materials 2022, 15, 3965. https://doi.org/10.3390/ma15113965 https://www.mdpi.com/journal/materials