Editors: | F. Kongoli, M.-C. Gomez-Marroquin, M. Contrucci, N. Lacerda, F. V. Cancado, M. de Souza, R. Valladares |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2018 |
Pages: | 184 pages |
ISBN: | 978-1-987820-82-9 |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
There is a great diversity of minerals containing manganese. The important ones are psilomelane (Ba,H<sub>2</sub>O)<sub>2</sub>Mn<sub>5</sub>O<sub>10</sub>) pyrolusite (MnO<sub>2</sub>), criptomelane (K(Mn<sup>++++</sup>,Mn<sup>++</sup>)<sub>8</sub>O<sub>16</sub>), rhodochrosite (MnCO<sub>3</sub>) and some ore with high content of iron oxides. For ferro-manganese production, the accepted reduction steps are gas/solid reaction to reduce higher oxides to lower ones (MnO<sub>2</sub>> MnO and Fe<sub>2</sub>O3>FeO) and at temperatures higher than around 1000°C gas/solid, solid/solid, liquid/solid and liquid/liquid reactions. The liquid/liquid and metal/slag reactions are the predominant ones at conventional Smelting Electric Furnace, for effective reduction of MnO>Mn at temperatures (~>1300°C) and it involves slag formation, dissolution of MnO in the slag, reduction of Mn++ in slag by carbon embebeded by slag or by slag/metal reaction by carbon dissolved in liquid Fe-Mn(MnxCy). The result is low production rate due to slow reactions. This paper analyzes some important effects from the characteristics of the manganese ores for ferromanganese production, such as: gangue and mineral compositions regarding the components that may form liquid phase during high temperature processing, impairing the rate of reduction of manganese ore-carbon composite. It may conclude that ores with high manganese content and low content of silica, iron oxide, (and others which may form liquid phase-slag at temperatures around 1350/1400°C) are prone to having better reduction behavior and consequently higher productivity and lower energy consumption.