China
Africa
Explore chapters and articles related to this topic
Minerals of base metals
Published in Francis P. Gudyanga, Minerals in Africa, 2020
Manganese (Mn) is a paramagnetic [512] metal which is easily oxidised in air and forms rust in water containing dissolved oxygen. Because of its reactivity, manganese does not exist as a free element in nature but is found in many minerals generally in combination with iron, which it resembles chemically and shares a spatial relationship. The principal mineral containing manganese is pyrolusite (MnO2), but also braunite (Mn2+Mn63+)(SiO12), psilomelane (Ba,H2O)2Mn5O10) and rhodochrosite (MnO3) to lesser extent.
Manganese Particles in Freshwaters
Published in Jacques Buffle, Herman P. van Leeuwen, Environmental Particles, 2018
Richard R. De Vitre, William Davison
Mn-specific minerals are quite scarce and, in common with other transition metal minerals, often include two or more formal oxidation states. Among the more common Mn minerals are the oxides and oxyhydroxides such as pyrolusite (MnO2) and psilomelane (BaMn(II)Mn(IV)8O16(0H)4), and in near surface deposits manganite (MnOOH), braunite (Mn,Si)2O3 and hausmanite (Mn3O4). Less common manganese minerals, generally found in more reducing environments, include pyrochroite (Mn(OH)2), manganosite (MnO), and alabanite (MnS). Finally, rhodochrosite (MnC03) is found in sedimentary rocks, and as an impurity in carbonate rich ores such as calcium carbonates through ionic substitution since the charge and ionic radii of Mn2+ and Ca2+ are quite similar.
A Review of Low Grade Manganese Ore Upgradation Processes
Published in Mineral Processing and Extractive Metallurgy Review, 2020
Veerendra Singh, Tarun Chakraborty, Sunil K Tripathy
These ores mainly contain SiO2 as the major gangue mineral. Silica association with manganese is found in two major forms. Some of the manganese ores contain chemically combined silica in the form of manganese minerals, such as braunite (Mn2+Mn3+6SiO12). This silica cannot be removed by physical beneficiation and require grinding and a complex beneficiation process. Other kinds of ores contain quartz and other silica bearing gangue minerals which can be removed by specific gravity-based separation methods. Gravity separation or a combination of magnetic and gravity separation processes are considered as the most suitable upgradation processes for these kinds of ores. These have been discussed in the following section.