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Ferroalloys Waste Production and Utilization
Published in Sehliselo Ndlovu, Geoffrey S. Simate, Elias Matinde, Waste Production and Utilization in the Metal Extraction Industry, 2017
Sehliselo Ndlovu, Geoffrey S. Simate, Elias Matinde
Manganese is ubiquitous in the environment and is the twelfth most abundant mineral in the earth’s crust (Post, 1999; Steenkamp and Basson, 2013; Tangstad, 2013a). It is proposed that the crustal rocks contain about 0.1% Mn, and is second only to iron as the most common heavy metal (Post, 1999). Geochemically, manganese resembles iron in that the lower-valence forms are highly soluble, mobile and reactive, whereas the higher-valence forms are highly insoluble, immobile and both chemically and physically resistant (Corathers and Machamer, 2006). Furthermore, manganese in ores exist as a component of various minerals, mostly in the form of oxides, sulphides, carbonates and silicates (Olsen et al., 2007; Steenkamp and Basson, 2013; Tangstad, 2013a), with the most commonly occurring manganese minerals being pyrolusite, rhodochrosite, rhodonite and hausmannite (Post, 1999; Howe et al., 2004; Chetty, 2010; Steenkamp and Basson, 2013; Tangstad, 2013a). Table 5.4 shows some of the typical manganese-bearing minerals commonly found in the Earth’s crust (Chetty, 2010; Steenkamp and Basson, 2013; Tangstad, 2013a).
Manganese ores in black shales sequences in the Western Carpathians, Slovakia
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
I. Rojkovič, D. Ozdin, L. Puškelová, A. Svitáčová
Dominant minerals of manganese ore in the metamorphosed Early Paleozoic black shales are rhodonite, Ca-rich rhodochrosite and Mn-rich calcite accompanied by other silicate minerals (Kantor 1954, Faryad 1994, Rojkovič 1999). The following three association of minerals were distinguished: metamorphic association: rhodonite, rhodochrosite, tephroite, spessartite, anthophyllite, pyroxmangite, magnetite, pyrophanite, muscovite, manganpyrosmalite, albite, rutile, allanite-(Ce),hydrothermal association: Mn-rich calcite, pyrite, pentlandite, sphalerite, chalcopyrite, pyrrhotite, cobaltite, ullmannite, galena, chamosite, bementite, quartz,supergene association: todorokite, pyrolusite, cryptomelane, goethite and “limonite”.
Investigation of transformations of low-grade manganese ore during the roasting process
Published in Mineral Processing and Extractive Metallurgy, 2023
Heba Ali, Mohamed El-Sadek, Hesham Ahmed
At 1000°C, braunite was formed according to the reaction. At 1200°C, rhodonite was formed by a reaction of hausmannite and quartz according to the reaction. Also, at this temperature, braunite may react with quartz to form rhodonite, Eqns. (7) to (9) are associated with the liberation of oxygen and may be retarded by atmospheric oxygen during the roasting process, causing stabilisation of mass at 1000°C and 1200°C, as observed in Figure 7. It is well known that at higher temperatures, braunite can dissociate, according to Eqns (10 and 11). and hausmannite can react with rhodonite, according to Eqn (12). depending on the fugacity of oxygen in the system. To demonstrate this, two samples were roasted at 1000°C for one hour, one in air and the other in an argon atmosphere. As shown in Figure 9, rhodonite formed in the air atmosphere according to equation (8), while in the argon atmosphere, hausmannite and silica are present unreacted due to deficiency of oxygen.