Executive Summary : | Pyrite (Fes2) sulfur is one of the most abundant and widespread distributed sulfide minerals on our planet. This pyrite plays a very important role in geological formation, geochemistry, biology, and environmental processes. Pyrite is frequently associated with valuable sulfide minerals such for example chalcopyrite (CuFes2), sphalerite (Zns), and galena (Pbs). Pyrite is also present as an undesired inorganic constituent in coal and an overburden material of coal. When pyrite material is exposed to the environment (water and air), due to anthropogenic activities or natural processes, it oxidizes to form concentrated sulfuric acid. This process leads to the acidification of natural resources, such as rivers, streams, and lakes, and causes severe pollution to the water and land. In general, coal mines get affected during coal extraction, but unutilized or closed mines also generate this acid with time. This AMD is considered one of the major environmental challenges in regions where sulfide-rich soils are available such as NER of India, due to natural and anthropogenic activities. The following equation describes the pyrite oxidation in the presence of water or moisture and air, which results in the formation of aqueous Fe(II) ions, acid (H), and sulfates (sO₄²). The above AMD is one of the serious environmental problems in mining industries and has been affecting the various coalfields (including Makum, North Eastern Coalfields Limited, and Assam). It has created environmental hazards with long-term effects. AMD is one of the most serious threats to water and soil around the mine area of any region. Mobilization of hazardous elements. AMD can devastate rivers, streams, and aquatic life for hundreds or even thousands of years under the ‘right' conditions. These issues related to the environmental impact of the coal mining industry i.e. AMD must be assessed and monitored for its management. As per the best of our literature survey, it is observed that the coating approach has not yet been utilized by Indians, particularly for Indian coals, to better understand its effect on AMD mitigation. The encapsulation or coating of the pyrite mineral present in the coal leads to reduced contact with air and oxygen and results in no acid generation. |