Processing Coalmine Overburden Waste Rock as Replacement to Natural Sand: Environmental Sustainability Assessment
Anshumali Mishra, Sarat Kumar Das, Krishna R. Reddy
Abstract
Waste rock dumped beside a surface coal mining site is termed coalmine overburden (OB) and is found suitable as a construction material. It requires preprocessing to be converted into the final construction material. The waste rock (cradle) processing to the final product (gate) involves transportation to the processing plant, crushing, screening, washing, and transportation from the processing plant to the client or project site. Preprocessing will cause environmental impacts. The present study performs a cradle-to-gate environmental impact assessment of waste rock to replace natural sand at a coal mine near Dhanbad, India. Life cycle environmental sustainability is assessed using the SimaPro® CML-IA baseline V3.07/EU+3 2000 impact method with the Ecoinvent 3.0 inventory. The data used was collected from an operational plant in the nearby area. The layout of a typical processing plant is also proposed in the study. The environmental impacts are reported in terms of abiotic depletion, global warming potential, ozone depletion potential, terrestrial ecotoxicity, human toxicity, eutrophication, acidification, and eutrophication. The manufacture of overburden sand (OBS) using a sustainable fuel and energy mix is more environmentally friendly. The environmental impacts can be drastically reduced if crushing is carried out using an onsite or mobile crushing plant.