Coal mining and the environmental impact of Acid Mine Drainage(AMD): A review

Abstract

In spite of the growing global initiatives towards achieving clean energy, coal remains a dominant source of electricity generation, a fuel for iron and steel production, an important entity among road construction materials and a commodity for foreign exchange earnings for many nations. Coal mining from old and active sites remains a source of an environmental problem described as acid mine drainage (AMD). AMD is produced when sulfide present in waste rocks or tailings in coal mines reacts with air and water in a microbes facilitated oxidation to form solutions with high acidity. The acids formed by these chemical and biological conditions further release heavy metals present in the host rock in concentrations higher than are acceptable by environmental standards (pb;0.01, Zn;5, Cu;2, Fe;0.3 mg/l as prescribed by WHO and Encyclopedia of Environmental Science,2000) such that soils, surface and underground waters are contaminated. Consequently, the human population which derives her livelihood in the mine zones, in form of crop production and fishing/modern aquaculture is endangered by terminal health diseases. This article aims at bringing forth, the urgent need to work towards achieving goal six of the United Nations Sustainable Development Goals, 2030 (SDGs-6) which is clean water and sanitation while enriching the knowledge repository of the environmental problem for the purpose of teaching, research, community services and policy making. An overview of AMD menace, variables which influence its formation, selected areas that have been impacted, and a brief analysis of its treatment cost have been discussed with a list of concluding remarks in the paper.
 Keywords: Coal, Mining, Environmental , AMD

Acid mine drainage (AMD) contamination in coal mines and the need for extensive prediction and remediation: a review

“…Effluents from Odagbo coal mine are characterised by high levels of toxic metals such as nickel, copper, lead, arsenic, iron and have impacted water bodies around the mine zone (Ameh et al, 2014;Momoh et al, 2017). The pH values obtained for discharge waters, streams and boreholes in a recent field study (Ojonimi et al, 2020) around the mine range between 1.2-2.3, 3.5-4.5 and 5-6, respectively. Thus, the ongoing artisanal mining in the community, as well as previous conventional activities in the area, have led to AMD contamination which could constitute serious threats to the health of the host community.…”

“…These include; amount of acid generating (sulfide) minerals present in the ore [pyrite (FeS2), chalcopyrite (CuFeS2), sphalerite (ZnS), galena (PbS), cinnabar (HgS) and molybdenite (MoS2)], quantity and type of potential contaminants present, type of carbonate minerals such as calcite (CaCO3) present, mineral surface area available for reaction, particle size of the waste, availability of water and oxygen and the bacterial community present (Thorsten, 2013). These factors were extensively discussed by Ojonimi et al (2020) in a previous review of acid mine drainage in coal mines. This article suggests a robust geochemical characterization program that provides a basis for risk assessment and closure of coal mines.…”