Assessment of environmental impact of digging and loading equipment in surface coal mining

This paper presents research on the environmental impact of digging and loading equipment used in surface coal mining. Environmental impact was assessed through the measurement of equipment exhaust and dust emissions, and sound level. In this study, exhaust emission refers to carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOx) and volatile organic compounds (VOCs). Dust generation refers to fine particles (PM2.5), inhalable particles (PM10) and total suspended particulate matter (TSP). Sound level refers to the sound pressure level at different distances from the equipment. Modeling of the environmental impact of digging and loading equipment was conducted using the Microsoft Visual Studio.NET software package. This research was a part of a broader project involving the development of a software system for the selection of productive, cost-efficient and ecofriendly mining systems, sponsored by the Appalachian Research Initiatives for Environmental Sciences (ARIES). This research may assist mining professionals in quantifying the environmental impact of digging and loading equipment, and developing strategies for reducing the overall impact of such equipment in surface mining. Introduction Major environmental hazards in digging and loading operations in surface mining include exhaust emission, dust emission and noise exposure. The equipment used in this process not only contributes to a significant sound level in mining areas, but also accounts for a substantial fraction of the emissions of primary air pollutants, including dust and exhaust emissions. Dust emission is categorized according to the size range of the component particles. Some dust particles are large, and others are so small that they can be detected only by a microscope. Inhalable particulate refers to the fraction of dust particles that can be breathed into the nose or mouth. Thoracic particulate refers to the fraction of particles that can penetrate the head airways and enter the airways of the lung. Respirable particulate refers to the fraction of inhaled airborne particles that can penetrate beyond the terminal bronchioles into the gas-exchange region of the lungs (Soderholm, 1989). Particles ranging in size from 0.1 micrometer to about 30 micrometer in diameter are referred to as total suspended particulate (TSP) matter. Particulate matters with a diameter of 10 micrometers collected with 50% efficiency by a PM10 sampling collection device are called inhalable particles (PM10). Fine particles (PM2.5) are defined as particulate matters with a diameter of 2.5 micrometers collected with 50% efficiency by a PM2.5 sampling collection device (EPA, 2012). In other words, TSP includes a broad range of particle sizes, including fine, coarse and super-coarse particles. The PM10 includes coarse and fine inhalable particle sizes, and fine particles are called PM2.5. The U.S. Environmental Protection Agency (EPA) regulates fine and inhalable particles. The inhalable particles pose the greatest problems because they can get deep into lungs, and some may even get into the bloodstream. Fine particles settle quite slowly in the atmosphere as compared to coarse and supercoarse particles. Normal weather patterns can keep PM2.5 particles airborne from several hours to several days. The PM2.5 particles can cause health problems due to their potentially long airborne retention time and the inability of the human respiratory system to defend itself against particles of this size (EPA, 2012). Dust particles can also be a safety hazard by impairing the equipment operator’s visibility (Reed and Organiscak, 2005). Although TSP is not regulated by the EPA, in some cases they may need to be reported for metals; thus, the TSP emission needs to be calculated to determine metal emissions (NPI, 2012). Paper number TP-12-057. Original manuscript submitted November 2012. Revised manuscript accepted for publication April 2013. Discussion of this peer-reviewed and approved paper is invited and must be submitted to SME Publications Dept. prior to Sept. 30, 2014. Copyright 2014, Society for Mining, Metallurgy, and Exploration, Inc.