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Introduction
Published in S. Komar Kawatra, Advanced Coal Preparation and Beyond, 2020
There are many known compounds of iron and sulfur, as shown in Table 1.4. The forms that are generally accepted as occurring in coals in significant quantities are pyrite and marcasite, which together are frequently referred to as “pyritic sulfur.” Pyritic sulfur occurs in coal as discrete inclusions of iron disulfide and generally accounts for approximately 30%–70% of the total sulfur in U.S. coals. Pyrite is the most commonly reported sulfide mineral and is ubiquitous in coal, although marcasite has often been found in lesser amounts (Gray et al., 1963). Pyrite and marcasite both have the chemical composition FeS2, but they are dimorphs, which are minerals that are identical in their chemical composition, but different in crystalline form. Pyrite has a cubic crystal structure, while marcasite crystals are orthorhombic. The two can be conveniently distinguished by X-ray diffraction methods. It is believed that marcasite forms when the original coal deposition environment was acidic (Rimmer and Davis, 1986).
Acid Rock Drainage and Metal Migration
Published in Mritunjoy Sengupta, Environmental Impacts of Mining, 2021
Marcasite (Table 6.1) is a low-temperature iron-sulphide mineral that may form instead of pyrite and which reportedly has a higher rate of acid generation under oxidizing conditions than crystalline pyrite. Marcasite may also be found in higher temperature paleoenvironments where it is metastable with respect to pyrite at temperatures >157°C.
Assessment of hazard on human health and aquatic life in acid mine drainage treated with novel technique
Published in Human and Ecological Risk Assessment: An International Journal, 2019
Sukla Saha, Priti Saha, Alok Sinha
Acid mine drainage (AMD) is the process for the generation of acidic water from active as well as abandoned mines. AMD is characterized as low pH (2–3) with enhanced heavy metal and anion concentration. It forms due to the oxidation of pyrite and other sulfide bearing mineral such as marcasite, chalcocite, pyrrhotite embedded in geological strata. AMD causes severe problem in gold and coal mining area in Johannesburg, South Africa as well as north-eastern, western and northern coalfield of India (Ochieng et al.2010; Merkel and Mandy 2011; Naicker et al.2003; Baruah et al.2006; Equeenuddin et al.2010; Sahoo et al.2012; Tiwary 2001). The acidic and heavy metal enriched water flows to nearby water bodies, which cause potential threat to aquatic life and the human health. AMD contains precipitation of iron oxides and hydroxides, which is very fine in nature. It settles at the waterbed along with the fine silt and makes the waterbed smoother. Therefore, the benthic organisms that feed on the bottom of the water bodies are not able to take the food any more. Consequently, the food sources reduce for the animals present at top of the aquatic food chain. It makes a negative impact on the total food chain as these benthic organisms are at the base of the aquatic food chain (Gray 1996; Ndlovu et al.2013). Bioaccumulation of various heavy metals such as cadmium, copper, lead, and zinc are found to be highly toxic to aquatic life. Moreover, various physiological activities including ion exchange with water and respiration are pH dependent, which take place when the pH of the water is in neutral range (6–9). As the pH of the drainage water reaches to 5, non-desirable plankton and mosses start to overspread and population of fish declines. (RBI 2004; Lenntech 2014). Heavy metal pollution also possesses adverse effect on human health (Ying et al.2016; Qu et al.2012). Different metabolic functions are disrupted in human being due to accumulation of heavy metals into vital organ like brain, heart, kidneys, liver, and interrupt their functions. They also slow down the process of adsorption, or displace the important nutritional minerals, which can cause carcinogenic or non-carcinogenic diseases (Singh et al.2011)