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Heavy Metals
Published in Abhik Gupta, Heavy Metal and Metalloid Contamination of Surface and Underground Water, 2020
Manganese (Mn), the second most abundant heavy metal and the fourth most abundant metal after aluminum, iron, and calcium, has an atomic number of 25, an atomic weight of 54.938, and a density of 7.43 g cm–3. The oxides, carbonates, and silicates of manganese are the most common mineral sources of this metal. It can exist in eight oxidation states, the most important being +2, +3, and +7. Pyrolusite, which is manganese dioxide (MnO2), is the most important commercial source of manganese. This mineral is found in sedimentary deposits. The other, less important, sources include carbonate accumulations of rhodocrosite (MnCO3) and stratiform deposits. However, pyrolusite is mostly mined in opencast mines for extracting manganese. Manganese is used in the production of steel, especially for the production of ferromanganese alloy steels. It is used as an oxidizing agent, in dry cell batteries, in pigments, to decolorize glass and making colored glass, as a catalyst, and in fertilizers and fungicides (Encyclopaedia of Occupational Health and Safety 2012).
Water Treatment
Published in Frank R. Spellman, The Science of Water, 2020
Manganese, like iron, is a naturally occurring mineral found in many water supplies. When the concentration of manganese exceeds 0.05 mg/L, black stains occur on fixtures and clothing. As with iron, this increases customer costs for cleaning and replacement of damaged fixtures and clothing. Iron and manganese are commonly found together in the same water supply. Iron and manganese and discussed in detail later.
Toxicology of CERCLA Hazardous Substances
Published in Barry L. Johnson, Impact of Hazardous Waste on Human Health, 2020
Three examples of CNS toxicity illustrate the range of adverse effects. First, severe, chronic exposure to manganese can cause effects that resemble Parkinson’s disease. The pattern of chronic manganese toxicity includes impaired speech, incoordination, unsteady gait, speech difficulties, and lassitude. Second, high exposure to mercury can cause a psychologic condition called erethism (Rodricks, 1992). Signs of this toxicity include excessive timidity, self-consciousness, inability to concentrate, and loss of memory. Third, toxic exposures to carbon disulfide (CS2) have occurred in the rayon and rubber industries where the solvent was used in production processes. Very high exposures produced severe psychoses, but at much lower levels, no significant changes were found in the psychologic function of rayon workers (Putz-Anderson et al., 1983).
Processing of low grade manganese ore in submerged arc furnace
Published in Canadian Metallurgical Quarterly, 2023
M. Eissa, H. El-Faramawy, T. Mattar, A. Ahmed, S. Ghali, M. El-Fawakhry, E. M. Kotb
Manganese is an essential element in the steelmaking process for de-oxidation and for increasing and enhancing the properties of the produced steel. Its future demand has been predicted to grow parallel with the increase in steel production. In steelmaking, manganese has mainly used in the form of ferroalloys (SiMn and FeMn). In the last decades, the world is now facing a real problem regarding the depletion of high and medium grade ores. The global data on manganese resources indicates that the large proportion of manganese ores around the world, reaching 80%, do not meet the specifications required for the production of high-quality manganese ferroalloys. So, the exploration of new manganese resources and utilisation of under-specified ores have become necessary. The exploitation of low-grade manganese ores has become a major challenge in order to meet the manganese industry requirements.
Nano MNO2 production from fine-grained and low-grade manganese ore using a mixture of citric acid and molasses as reductant
Published in Canadian Metallurgical Quarterly, 2023
Havvanur Ucbeyiay, Y. Ramazan Eker, Emine Ozkan
The increase in demand for manganese alloys and compounds due to their wide use in industry has created an important need for the enrichment of the ores containing manganese (Mn). Generally, high grade manganese ores are preferred in industry. Manganese (Mn), which is widely used in the production of high-quality steel (95% of manganese ore produced annually), is also used in various industries, including chemical, paint, fertiliser and battery industries [3]. It was also noted that the world annual demand for manganese has increased significantly in recent years due to increased steel production [4,5]. Most of these industries consume manganese ores containing >78% MnO2, <5% SiO2 and <5% Fe2O3. Especially in the battery industry, manganese ore containing 70-90% MnO2 and low Fe (2.5–4%) is consumed. It has also important applications such as purification, catalyst and oxygen transport [6,7]. According to the United States Geological Survey [8] report, World manganese reserves are approximately 760 million tons, mostly in South Africa (230 million tons), Ukraine (140 million tons), Australia (99 million tons). While the Mn content in the reserves varies between 20% and 60%, a significant part of these reserves are in medium and low grade values (Mn: 20–35%) [9]. However, about 30% of high-grade Mn ores are converted to low-Mn-grade manganese ores during mining operations such as crushing, beneficiation and transportation [10].
The impact of informal settlements on the surface water quality: a baseline analysis of the Kaalspruit in Tembisa township, South Africa
Published in Urban Water Journal, 2022
MS Morole, KY Yessoufou, SA Bufo, IT Rampedi, LS Modley
Manganese levels were intolerable and above Chronic Effect Value (CEV) according to aquatic ecosystem guidelines (Department of Water Affairs and Forestry (DWAF) 1996a) and are considered acceptable for irrigation but only over the short term according to irrigation guidelines (Department of Water Affairs and Forestry (DWAF) 1996b). Chronic Effect Value is considered as a concentration above which up to 5% of aquatic biota are expected to experience chronic effects (Department of Water Affairs and Forestry (DWAF) 1996a). Manganese naturally occurs in rocks and soil and may sometimes be present due to underground pollution sources. It is one of the essential elements found in living organisms, which means it is essential for other organisms, including humans, to survive, but can be toxic upon exposure to high concentrations (Hermes et al. 2013). In the current study, the measured Mn concentrations showed no distinct pattern with the sampling sites. A study conducted by Hermes et al. (2013) to investigate Mn concentrations in the Pardinho River (Southern Brazil) showed no direct relationship between high concentrations of Mn and anthropogenic activities/land uses, with manganese levels indicating very minimal differences across different anthropogenic activities. It is, therefore, concluded that the observed manganese concentrations might be of natural origin.