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Practical Applications: Landfills
Published in William J. Deutsch, Groundwater Geochemistry, 2020
Ferrous iron, Fe2+, dominates the next zone. It forms from the dissolution of ferrihydrite, and although it does participate in cation exchange reactions, the typical large amount of ferrous iron produced overwhelms the exchange capacity of most systems to significantly retard its movement. In the presence of high ferrous iron and carbonate concentrations, siderite (FeCO3) may form. The precipitation of this mineral usually limits the upper concentration of iron because carbonate is present in excess of the iron concentration. High dissolved levels of manganese may also be present in the iron zone; however, as conditions become more oxidizing the iron will reprecipitate as ferrihydrite [Fe(OH)3], leaving Mn(II) as the dominant, dissolved redox-sensitive species. The manganese carbonate mineral rhodochrosite (MnCO3) may form in the zones where manganese concentration is elevated. Finally, downgradient of the landfill where the plume has sufficiently mixed with fresh water or been subject to the diffusion of gases from the soil vapor, dissolved oxygen will be present at levels greater than 1 mg/L and the system will be oxic again.
Activity of the catalyst obtained by processing of high-magnesia siderites
Published in Vladimir Litvinenko, Topical Issues of Rational Use of Natural Resources 2019, 2019
A.N. Smirnov, S.A. Krylova, V.I. Sysoev, V.M. Nikiforova, Zh.S. Zhusupova
The basis of siderite ores is iron carbonate - FeCO3, which scarcely can be found naturally in pure form and often has an isomorphic admixture of magnesium, as well as manganese, calcium and other elements (Dziubinska et al. 2004). Iron carbonate forms a continuous isomorphic series with magnesium carbonate - from pure FeCO3 (siderite) to pure MgCO3 (magnesite). In the isomorphic series, stable members of the series are distinguished depending on the MgCO3 content: sideroplesite - up to 30%; pistomesite - from 30 to 50%; mesitite - from 50 to 70% and breynerite - from 70% and higher.
Minerals
Published in F.G.H. Blyth, M. H. de Freitas, A Geology for Engineers, 2017
F.G.H. Blyth, M. H. de Freitas
Siderite occurs in clay-ironstone beds and nodules in the Coal Measures; formerly worked as a source of iron in British coalfields. The mineral is also found in rocks where Fe-carbonate has replaced the original calcium carbonate of a limestone (p. 126) and occurs in many of the marine sedimentary oolitic iron ores of Mesozoic age in Britain and continental Europe. In bog-iron ores siderite was precipitated direct from the water in lakes (p. 129). Found as brown rhombhedral crystals (trigonal), and also massive.
Thermal Decomposition of Siderite Ore in Different Flowing Atmospheres: Phase Transformation and Magnetism
Published in Mineral Processing and Extractive Metallurgy Review, 2023
Xinran Zhu, Yuexin Han, Yongsheng Sun, Peng Gao, Yanjun Li
Siderite is an iron-bearing carbonate mineral and is the most abundant in sedimentary iron formation on Earth (Kholodov and Butuzova 2008; Kholodov, Butuzova and Yu 2004a; Kholodov and Yu 2004b). The well-known Bakal siderite ore deposit in the Ural, Russia, is a major iron ore material for sintering in the steel industry (Vusikhis, Leont’Ev and Kudinov 2017; Vusikhis et al. 2016). However, owing to the low iron grade, a theoretical Fe content of 48.27%, easy sliming, and high impurity content of Mg, Mn, and Ca in the lattice structure, producing iron concentrate from siderite ore is difficult using conventional methods such as flotation, magnetic separation, and gravitational separation (Bai et al. 2014; Li et al. 2012; Yin, Han and Xie 2010). Thus, siderite ore is not considered a suitable iron ore material for the iron and steel industry, particularly in Australia, Brazil, and India, which have abundant iron resources of hematite, goethite, and magnetite. However, due to the depletion of easy-processing iron ore, the exploitation of refractory iron ore has attracted significant interest.
Effect of Magnesium Substitution on Siderite Thermal Decomposition in Air Atmosphere
Published in Mineral Processing and Extractive Metallurgy Review, 2023
Xinran Zhu, Yuexin Han, Peng Gao, Yongsheng Sun
Siderite (FeCO3) is a typical iron-bearing carbonate mineral, and the Fe is usually substituted by Mg, Mn, and Ca in the lattice structure (Dubrawski 1991; Goldin and Kulikova 1984; Kissinger, Mcmurdie, and Simpson 1956). Natural siderite is characterized by thermal instability, and early studies indicated that decomposition behaviors always varied significantly in various atmospheres (Chun, Zhu, and Pan 2015; Dhupe and Gokarn 1990; Gallagher and Warne 1981a, 1981b; Zhu et al. 2022b). Particularly, the thermal instability of siderite has been studied under oxidizing conditions (Koshy et al. 2018; Luo et al. 2016; Pan et al. 2000; Yui 1966; Zhang et al. 2020). Results indicated that magnetite (Fe3O4) was the primary iron oxide phase during oxidation decomposition. Further oxidations from magnetite to maghemite (γ-Fe2O3) or hematite (α-Fe2O3) occurred depending on the roasting temperature, oxygen fugacity, and atmospheric pressure. The possible reactions during the oxidation decomposition are expressed as follows: