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Manganese is widely used in the iron and steel industry, batteries and other fields. The amount of the manganese oxide ores existing in China coeval with iron and their manganese-to-iron ratio is low. A study was conducted on a synchronous reduction roasting-magnetic separation of a ferromanganese ore with high content of iron taken from South Africa using CO as reductant. Under the conditions of 750°C roasting temperature, 40 min roasting time, 30% CO concentration roasting atmosphere and − 0.074 mm accounting for 82.56% grinding fineness, the iron removal rate was close to 70% through magnetic separation, with the grade and manganese recovery of manganese concentrate reaching 49% and 72.50% and the manganese-to-iron ratio increasing from 2.5 to 5.92. The X-ray diffraction analysis indicated that Mn2O3 and Fe2O3 in the raw ore was reduced to MnO and Fe3O4, respectively, without forming the intermediate product Mn3O4 in a weak reducing atmosphere. The SEM-EDS analysis of the roasted product showed that the simultaneous reduction of manganese and iron oxides could be achieved when the roasting temperature reaches 750°C. The crystal forms of MnO and Fe3O4 were more perfect, and the coexisting grains of Ca, Si and Al clustered further with increasing roasting temperature. [ABSTRACT FROM AUTHOR]

Rare earth elements (REE) of the host rocks (Fe-siliceous rocks) and manganese ores of the Nchwaning Mine (Hotazel Formation, Kalahari manganese field) were studied. An important feature of manganese ores and host rocks (Fe-silicites) is the presence of negative and positive cerium (Ce/Ce*) and europium (Eu/Eu*) anomalies. This testifies to the complex and long history of the formation of manganese ores. Initial metal-bearing (Mn, Fe) sediments of a shallow-water basin with a negative cerium anomaly (Ce/Ce*) were enriched in europium (positive Eu/Eu*) at different stages of lithogenesis both during sedimentation (underwater discharge of hydrothermal fluids), and subsequent processes of hydrothermal transformation of the ore-bearing strata. The source of manganese could be basaltic andesites of the underlying Ongeluk Formation. [ABSTRACT FROM AUTHOR]

Potentially toxic elements (PTEs) pose a significant threat to aquatic ecosystems. This study investigated the content and potential sources of PTEs (Cr, Mn, Ni, Cu, Zn, Cd, Pb) in water, sediment, and dominant aquatic plants (Hydrilla verticillata and Spirogyra varians) in the Xiaojiang River, located near the Zhaiying manganese mine in Guizhou Province, China. Correlation analysis, principal component analysis (PCA), and cluster analysis were employed to assess PTE distribution and potential sources. Water PTE concentrations complied with the Class II standard (GB3838-2002), indicating no water pollution. However, sediment PTE levels exceeded background values, particularly Mn, which exhibited moderate to strong contamination. Cd also showed moderate contamination, posing a considerable ecological risk. Cd was the main potential pollutant with the highest contribution rate. Mn and Cd were therefore identified as priority pollutants requiring targeted abatement strategies. Mining activities likely represent the primary source, but combined pollution from vehicle traffic and agriculture might also contribute. Hydrilla verticillata demonstrated a higher capacity for PTE enrichment from sediment compared to Spirogyra varians, suggesting its potential for sediment remediation (except for Cu). A significant correlation existed between both plant species and sediment PTE content. PCA supported the association between S. varians and sediment PTEs. Linear regression analyses revealed better correlations between S. varians and sediment Mn, Ni, Cu, and Zn (0.77, 0.68, 0.82, and 0.79, respectively). Taken together, these findings suggest that S. varians serves as an effective bioindicator for monitoring sediment contamination with PTEs. [ABSTRACT FROM AUTHOR]

The pre-reduction of manganese ore using elemental sulfur under an inert atmosphere at temperatures above 600 °C is required for maximum MnO formation. Under atmospheric conditions, SO2 formation via sulfur oxidation leads to MnSO4, which again will dissociate to lower Mn oxides. Thus, excess energy is required for this conversion, thereby decreasing the overall energy efficiency. The optimum pre-reduction condition obtained is 800 °C, with a holding time of 4 hours at 0.5 S/Mn ratio. [ABSTRACT FROM AUTHOR]

The Middle Permian manganese deposit in Zunyi, northern Guizhou is one of the major manganese mining areas in South China. However, the age of this manganese deposit has not been accurately constrained. Previous studies have generally concluded that the formation of Zunyi manganese ores was linked with the early activities of the Emeishan Large Igneous Province (ELIP). In this study, we investigated the lithology and mineralization age of the Mn-bearing rocks in the study area and explored the connections between ELIP and the genesis of these rocks. Zircon samples from the Mn-bearing tuff in the Tuanxi section of Zunyi were used for zircon U-Pb chronological analysis by LA-ICP-MS method. The results constrain the deposition age of Mn-bearing rocks in Member 3 of the Maokou Formation was older than 266 ± 3 Ma, this age was closely related to the early stage of ELIP, but it was 5–10 Ma earlier than the main eruption of the Emeishan basalt. Combined with the regional paleogeography, we believe that the mantle plume activities prior to the main eruption of ELIP provided the tectonic stress, manganese source, and mineralization environment for manganese ore formation in the rift basin of the study area. [ABSTRACT FROM AUTHOR]

The paper reports original data on the isotopic composition (δ13С, δ18О) and major and rare earth element (REE) geochemistry of manganese ores in the Rodinauli section of the Kvirila deposit (Georgia). The δ13С (V-PDB) and δ18О (V-SMOW) values vary from –19.6 to –6.6‰ and from 21.1 to 29.1‰, respectively, in the carbonate ores; and from ‒14.9 to ‒5.5‰ and from 21.8 to 28.4‰, respectively, in the carbonate substance of cement of oxide ores. The studied ores are characterized by the presence of negative Ce anomaly ( up to 0.51) in majority of samples (both carbonate and oxide ores); the prominent Eu anomaly is absent. A conclusion has been made that the ores were formed both under conditions of early diagenesis of sediments and later, during catagenesis, with the participation of metal-bearing elisional solutions. [ABSTRACT FROM AUTHOR]

The world has moved into an era of hidden ore body exploration, necessitating the development of new prospecting and exploration methods. One promising approach is to use the deep convolutional neural network (DCNN) algorithm to extract spatial and correlation characteristics of multiple two-dimensional elements related to hidden ores. This paper explores this method on Datangpo manganese (Mn), constructing prediction datasets that includes geological, geochemical, geophysical and aeromagnetic features. Analyzing metallogenic conditions and control factors of Mn ores, we construct a Mn ore prediction model (Geo-DCNN) based on multiple geographical knowledge and DCNN. The Geo-DCNN model reaches ore-bearing accuracy of 79.11%, non-ore-bearing accuracy of 99.01%, overall accuracy of 95.35%, and loss value of 0.0227 after training. Based on analysis of ROC curve, P-R curve, field investigation, and target area verification, we discover that the prediction results of the Geo-DCNN model in northeast Guizhou have a high correspondence rate with known manganese deposits. This provides valuable insight for further ore exploration in the area. Additionally, the results indicate that the Geo-DCNN model is robust and portable, suggesting that it can be applied to metallogenic prediction practices for manganese ore in similar regions. [ABSTRACT FROM AUTHOR]

The Imini mining district (southern foreland of the intraplate Atlasic belt of Morocco) hosts the largest Mn resources of North Africa, consisting of two laterally extensive bodies of high-grade pyrolusite-rich manganese ore and a third discontinuous medium-grade coronadite-rich Mn ore in a ~ 10–15-m-thick Cenomanian–Turonian dolostone unit. Until now, the origin and timing of the Mn ore have been poorly constrained. New Pb isotopic ratios show that Triassic series (basalts and ferruginous sandstone) are likely the source of the metals. 40Ar/39Ar dating of K-Mn oxides shows that the Mn-rich orebodies formed during at least three periods: late Cretaceous to late Paleocene (> 58 Ma), late Eocene (ca. 36.3 Ma), and early Burdigalian to early Serravalian probably in two pulses at ca. 19–20 Ma and ca. 13 Ma. These periods coincide with three known building phases of the Atlasic relief during late Cretaceous, late Eocene, and the Early(?)-Middle Miocene. We therefore propose the Atlasic tectonics as the first-order control of the Mn mineralization. Periods with regionally high elevations modified the climate to wetter conditions that supplied meteoric water to feed temporary aquifers. Relief building created the required hydraulic head to sustain (1) fluid-rock interaction between O2-poor acidic fluids and the Triassic series, (2) migration of the metal-rich fluid, and (3) to overpressure fluid in the Imini depositional site. The decreasing thickness of Triassic series in front of the Imini anticline forced these low-temperature (< 100 °C) fluids to mix with oxygenated and alkaline ground waters in the karst system and precipitate Mn oxides. The N70°-oriented Atlasic tectonic structure controls the orientation of the Mn deposits. The late Eocene–Early/Middle Miocene uplifts generated additional supplies and/or in situ remobilization of the primary late Cretaceous medium-grade ore to form the high-grade pyrolusite-rich ore. [ABSTRACT FROM AUTHOR]

The research investigated the potential of natural ore with a low manganese content gradient, imported from the Tiouine region of Morocco, as an adsorbent of cadmium ions in a phosphoric acid medium. For the first time, the ore was prepared and used as adsorbent in three different sizes (60, 315, and 500 µm), and characterized by X-ray diffraction, fluorescence spectroscopy, Fourier transform infrared, and scanning electron microscopy. The chemical activation of raw ore by HCl and KOH at different temperatures was necessary to enhance the removal capacity of Cd(II) ions. The removal capacity was evaluated by studying the ore's particle size and different reaction parameters such as contact time, temperature, and cadmium ions concentration. The activation process improved the adsorption performance of the raw ore in a concentrated phosphoric acid medium. The very low quantity of manganese released by the natural ore during the phosphoric acid purification process proves its high stability. This work suggests the possibility of using manganese oxide ore in the treatment of liquid effluents contaminated by metal ions and more precisely to purify or reduce the cadmium content in industrial phosphoric acid. [ABSTRACT FROM AUTHOR]

Methylene blue is widely used in various industries. The discharge of industrial effluents with methylene blue residues may have hazardous effects on living systems. In this paper, the low-cost, eco-friendly, and abundant geoadsorbent natural manganese ore sand was used as an attractive material to remove methylene blue. The results indicated that the poorly crystalline manganese ore sand could simultaneously adsorb and degrade methylene blue. The pseudo-first-order and MnOII (I) kinetic models could describe the decolorization, but the latter had better predictive characteristics. The kinetics were affected by coexisting substances, but a decolorization efficiency of greater than 80% still could be achieved in actual water matrices. Characterization of manganese ore sand before and after use indicated that the degradation processes that occurred at pH values of 2, 3, 5, 7, and 10 included direct and indirect redox reactions. Specifically, the manganese ore sand behaved primarily as an oxidant at acidic pH, as a catalyst at alkaline pH, and simultaneously as oxidant and catalyst at a neutral pH. Possible degradation routes were proposed based on the suggested intermediates. The main behavior of the oxidant was demethylation of C–CH3 from methylene blue, and the degree of demethylation increased with decreased pH. As the catalyst, the C–N and C–S bonds on the central heterocycle could be further broken by manganese ore sand after demethylation. The performance of manganese ore sand is related to the content of high-valent Mn species. [ABSTRACT FROM AUTHOR]

The beginning of human settlement in the Hami Basin, located in the eastern part of Xinjiang, has been a focal question for the academic community in China. In particular, the thesis that the immigrating population from the Hexi Corridor since the late Neolithic founded the Tianshanbeilu culture has riveted the attention of scholars. Pottery wares, abundantly discovered at the synonymous cemetery of this culture, have played a key role in extrapolating population migration and cultural interaction. This paper aims to test the thesis by characterizing the chemical composition, painting pigment, and carburizing technique of 70 pottery samples from the cemetery with various scientific methods. It shows that the chemical compositions of the coarse pottery in the three colors of red, yellow, and gray, painted and unpainted alike, are remarkably different from those of fine pottery in black and red, indicating that the raw materials for the coarse and fine pottery samples are possibly procured from different sources; the pigments of the red slip and black paint are derived from hematite, black manganese ore, and carbon black; carburizing and polishing techniques are further applied to the gray coarse pottery; In combination with the compositional data of pottery samples from the Yaer cemetery also in the Hami Basin and the Xichengyi settlement in the Hexi Corridor, this paper finds that some pottery wares of the Tianshanbeilu culture were exchanged within the Hami Basin, but each site had its own production facility. No direct exchange of pottery wares with Xichengyi is attested; the similar style of pottery wares between the two sites may have resulted from population migration and technological exchange. [ABSTRACT FROM AUTHOR]

The transition from an open-pit to an underground space is inevitable to exploit deposits from greater depth. Crown pillar, a remnant ore usually left in between open-pit to underground mining that supports the terrain and aids in carrying out underground mining operations safely and its stability is vital. The design of crown pillar is majorly influenced by its thickness, span, slope angle, ore dip, depth of open-pit mining, rock mass quality, cohesion and friction angle. When the crown pillar is situated near the surface (shallow depth), it is synonymously named as the surface crown. The behaviour of the crown pillar is different from the surface crown due to variation in geo-mining conditions. As underground mining progresses, displacements around the crown pillar are generated and stresses reorients around it. This can be assessed through numerical simulation. To have a better understanding, this paper concentrates on crown pillar's stability and geometrical parameters influence on its stability. The field study is carried out at Ramrama manganese ore mine, where the transitioning takes place at shallower depth and FLAC3D 5.0 is used for numerical simulation work to analyse the behaviour of the crown pillar. From the results interpreted, it is found that the maximum amount of principal stresses decreases for the lower span, 8 m, of crown pillar with increase in slope angle and for the larger span as in case of 22 m span; the stresses generated are reduced in case of 38° slope angle and increased for 45° slope angle. Higher dip of orebody generates high amount of stresses in the pillar and with an increase in the depth of mining, high amount of displacements and stresses are observed around the crown pillar. [ABSTRACT FROM AUTHOR]

Results of studies for preparing complex Fe–Si–Mn–Al master alloy are presented. High-silicon lean manganese ores of the West Kamys ore deposit (18–30% Mn and 35–45% SiO2) and high-ash coal of the Saryadyr deposit (Kazakhstan) with an ash content of 45–55% are used as charge materials. Technological studies are conducted in an ore-thermal electric furnace with a capacity of 250 kVA. An experimental batch of master alloy with an average chemical composition is obtained, %: Mn — 20; Si — 42; Al — 16; P — 0.03; Fe balance. Dependences of aluminum, silicon and manganese content in final alloy on ratios Mnox + Feox + SiO2 + Al2O3)/Cso and Mnox/(Mnox + Feox + SiO2 + Al2O3) in an initial charge are revealed. The fundamental possibility and expediency of obtaining an aluminum silicon manganese master alloy of a new composition by a slag-free method with integrated use of all useful components of lean manganese ore and high-ash coal is demonstrated. An X-ray diffraction pattern of prototypes indicates that alloy phase composition is presented in the form of intermetallics — MnSi, Mn15Si26, Al2Fe3Si4, Al5Fe2, FeSi, and structurally free silicon. The resulting master alloys of selected composition are not subject to self-dispersal reactions. [ABSTRACT FROM AUTHOR]

In this article, a novel efficient and environmental reductive roasting-acid leaching technique was proposed by a combined pretreatment of the microwave heating and reduction of alkali lignin. Factors influencing the leaching of manganese from manganese oxide ores were investigated, such as heating modes (microwave heating and conventional heating), microwave roasting parameters and acid leaching parameters. The results indicated that the leaching ratio of manganese by microwave heating was significantly higher than that by conventional heating under the same conditions. The reduction of manganese oxide ores by microwave heating was completed at a roasting temperature of 150°C and a roasting time of 5 min with the addition of 50% alkali lignin with the reduction sequence of MnO2 → Mn2O3 → Mn3O4 → MnO. A 97.43% leaching ratio of manganese was obtained from the roasted ore, which was leached by a 1.5 mol/L concentration of sulfuric acid at a 50°C leaching temperature, 50 rpm stirring speed and a 10:1 liquid-to-solid ratio for 5 min. Compared to the conventional reductive roasting-acid methods, the proposed technique was performed at a considerably lower temperature and shorter time, with higher reducing agent utilization ratio to processing the different manganese oxide ores. [ABSTRACT FROM AUTHOR]

The rare earth elements (REE) geochemistry and the isotope (δ13C, δ18O) composition of manganese ores of the Chiatura (Georgia) deposit were studied. One of the major features of all types of manganese ores is negative cerium (Ce/Ce*PAAS) anomaly and the absence of europium (Eu/Eu*PAAS) anomaly. Oxide oolitic manganese ores were formed in oxic shallow marine environments. The content and distribution of REEs (in particular Ce and Eu) in these ores are connected mainly with ferrous oxides. The performed C- and O-isotope research in Mn-carbonates (oolitic and massive) has indicated that carbonate ores were formed by the participation of isotopically light CO2 which is a result of the oxidation of organic matter in the sediment strata by reducing environments of early diagenesis (and, partially, catagenesis) zone. Obtained negative cerium anomalies in the studied carbonate ores reflect the specific REE patterns in pore waters of sediments of earlier isdiagenesis zone of the Oligocene Chiatura's basin. The deficiency of cerium in this zone remains debatable and requires further study.Formation of manganese carbonates took place multistage by the input of incisional solutions of different chemistry into sea bottom waters and sediments. The absence of europium anomaly indicates about lack of hydrothermal solution input. [ABSTRACT FROM AUTHOR]

Increasing demand for manganese and rapid depletion of high-grade manganese ores grow attention to other resources. However, environmental impacts and techno-economic issues are the main challenges regarding manganese extraction from low-grade ores. This study investigated the environmental impacts of manganese recovery from low-grade ores and the synthesis of magnetic manganese ferrite. Two methods of synthesis were selected, a high-temperature synthesis using a furnace and a low-temperature method where the aging process compensates for the absence of a high-temperature regime. Life cycle analysis was conducted through the collected data to quantify and compare the environmental impacts. The high-temperature synthesis method surpassed the other process in almost all environmental categories adopted in the TRACI model. Additionally, sodium hydroxide has almost the highest contribution in both synthesis methods, while in the recovery process, electricity was the major contributor to all environmental categories. Besides electricity, sulfuric acid and sulfur dioxide play essential roles in the environmental impacts of the recovery process. Therefore, the low-temperature synthesis of manganese ferrite as a novel method is cost-effective and warrants the least environmental footprint. [ABSTRACT FROM AUTHOR]

Economic growth in developing countries, China in particular, has led to an increase in steel production and consumption in recent years. This trend is stimulating the demand for manganese ferroalloys. High-grade manganese ores from Australia, Africa, and South America are being supplied in larger quantifies to Asian ferroalloy plants, which used to consume low-grade manganese ores. Most experts believe that the future of the manganese industry will depend on the dynamics of steel production. In other economic areas, manganese consumption is expected to grow immensely due to the use of manganese for manufacturing lithium-ion and nickel–metal hydride batteries for electric vehicles. More than 90% of the manganese produced globally is utilized by the iron and steel industry in the form of various manganese ferroalloys. Manganese consumption in steelmaking in different countries depends on the range of smelted metal (oxygen-converter or electric steelmaking), the scientific and technical level of technological processes, and other factors. In the CIS countries, specific consumption of manganese amounts to 9 kg per 1 ton of steel, which is an impressive figure. In this research, we investigate the possibility of phosphorus removal into the gas phase during production of manganese ferroalloys. This will make it possible to involve domestic phosphorus-containing manganese ores in production for obtaining high-grade manganese ferroalloys. [ABSTRACT FROM AUTHOR]

One of the most controversial minerals in their origin and occurrence around the world is manganese deposits. The Abu Zenima area is rated one of the most economically important places where manganese ore deposits (Mn ODs) are located in the southwest Sinai microplate, Egypt. These deposits are confined with the Um Bogma Formation (UBF) and the reserves of this region are relatively small. In this study, optical and radar data are used in a new challenge as an attempt to reach the closest controls and setting of Mn ODs. Moreover, Frequency Ratio (FR) and Logistic Regression (LogR) predictive models are applied to integrate different geospatial thematic maps, to predict new potential resource zones for increasing the ranges of mining quarries. Landsat8 OLI, Sentinel-2A MultiSpectral Instrument and Radar (Sentinel-1B) data are combined for mapping Mn ODs locations and their relationship with geological structures and the surrounding rocks. Band ratio, Principal and Independent Component Analysis techniques and four classification algorithms were implemented to the optical' VNIR and SWIR bands. Unusually, the interferometric processing steps for Sentinel-1 data were made for understanding the tectonic features in the area. The FR and LogR models are validated during fieldwork with known Mn ODs locations. Results indicate that processed images are capable of differentiation of UBF which broadly distributed in the central and southern parts of the area. Mn ODs possibly formed by thermal events that attributed to paleo-volcanic events before the rift stage. The high accuracy of Log R model (0.902) suggests that high Mn ODs potential zones are identified within the intersected fault zones near granitic units. This integration is recommended for discriminating hydrothermally Mn ODs in other arid geographic regions. [ABSTRACT FROM AUTHOR]

The incorporation of hydrogen, which is a relatively unexplored reductant used during ferromanganese (FeMn) production, is an attractive approach to lessen atmospheric gaseous carbon release. The influence of hydrogen on the pre-reduction of carbonate-rich United Manganese of Kalahari (UMK) ore from South Africa was investigated. Experiments were performed in 70 pct CO 30 pct CO2 (reference), 70 pct H2 30 pct H2O, and 100 pct H2 gas atmospheres at 700 °C, 800 °C, and 900 °C. Calculated phase stability diagrams and experimental results showed good correlation. The pre-reduction process involved two reactions proceeding in parallel, i.e., the pre-reduction of higher oxides and the decomposition of carbonates present in the ore. A thermogravimetric (TG) furnace was employed for the pre-reduction of the ore in various atmospheres. The calculated weight loss percentage was used to determine the degree and rate of pre-reduction. It was found that the oxidation state of higher Fe- and Mn-oxides was lowered when treated in 70 pct H2 30 pct H2O and 70 pct CO 30 pct CO2, whereas FeO was metalized when using 100 pct H2. As for the intrinsic carbonates, the majority thereof were decomposed in the CO/CO2 atmosphere at 900 °C, and ≥ 700 °C in the H2/H2O and H2 atmospheres. Additionally, the degree and rate of reduction were accelerated by increasing the pre-reduction temperature and by employing a hydrogen-containing gas atmosphere (70 pct H2 30 pct H2O, and 100 pct H2). Scanning electron microscopy and electron microprobe analysis revealed the presence of three phases in the pre-reduced ore: (i) Mn- and Fe-rich, (ii) Mg- and Ca-rich, and (iii) Mg-, Si-, K-, and Na-rich. It was also found that there were no appreciable differences in porosity and decrepitation of the ores treated in the CO/CO2 and hydrogen-containing atmospheres. The use of a hydrogen atmosphere showed potential for the pre-reduction of carbonate-containing manganese ores as it accelerated the decomposition of the carbonates as well as facilitated the metallization of Fe-oxides present in the ore. [ABSTRACT FROM AUTHOR]

Iron ore and manganese ore were used as substrate of constructed wetlands (CWs) to enhance nitrogen (N) removal. However, the N purification performance in CWs filled with iron or manganese ore under antibiotics stress needs further study. In this study, three groups of CWs filled with river sand, limonite (a kind of iron ore), and manganese ore sand were constructed, which were named as C-CWs, Fe-CWs, and Mn-CWs, respectively. The effect and mechanism of the composite antibiotics sulfamethoxazole (SMX) and trimethoprim (TMP) on N removal in CWs were investigated. While the addition of SMX and TMP inhibited about 40% nitrification and promoted about 25% denitrification in all CWs, Fe-CWs and Mn-CWs always had better N removal performance than C-CWs. Changes in microbial community structure in CWs indicated that the better N removal performance in Fe-CWs and Mn-CWs was attributed to the presence of more abundant and diverse N-associated bacteria, especially Fe- and Mn-driven autotrophic denitrifying bacteria. What's more, the addition of iron ore or manganese ore contributed to the better N removal performance with highest relative abundance of N-transferring bacteria under antibiotics stress. [ABSTRACT FROM AUTHOR]

Wide variations of 87Sr/86Sr (0.70825‒0.70924) have been established at the Porozhinsk deposit in manganese ores and carbonates ascribed to the Pod"emsk Formation. These data, together with variations in the carbon (δ13C = –14.6...2.0‰, PDB) and oxygen (δ18О = 19.4...28.3‰, SMOW) isotope composition indicate different conditions of the formation of the studied rocks. The 87Sr/86Sr values in the studied dolomites of the Porozhinsk deposit are much higher than those of carbonate rocks (dolomites, limestones) of the Pod"emsk Formation from the Chapa River section. The position of the 87Sr/86Sr values of dolomites from the Porozhinsk deposit on the secular 87Sr/86Sr variation curve for Late Proterozoic ocean (Kuznetsov et al., 2014) suggests that the carbonate rocks attributed to the Pod"emsk Formation at the Porozhinsk deposit have younger age than carbonates of the Pod"emsk Formation from the Chapa River section. The Mn/Sr values usually taken as a criterion for the degree of secondary alteration of carbonates (in interpreting 87Sr/86Sr variations and discussing the suitability of the material for chemostratigraphic constructions) are not suitable for rocks formed in manganese ore sedimentation basins. [ABSTRACT FROM AUTHOR]

The prereduction reactions in the submerged arc furnace (SAF) are highly decisive of the total carbon, and energy consumption of the ferromanganese process. Therefore, understanding the dependency of prereduction behavior on ore characteristics and furnace conditions is of paramount importance. Prereduction behavior of Comilog, Nchwaning and UMK ores with solid carbon was studied in an open 75 kVA induction furnace set up simulating the conditions of an industrial SAF. In addition, the ores were thermogravimetrically studied with non-isothermal heating to 1000 °C in a flowing 70/30 CO/CO2 atmosphere. Gasification of carbon according to Boudouard reaction was considered significant for carbonate ores in induction furnace setup. UMK had a greater extent of prereduction compared to Nchwaning which is low in carbonates and Comilog which is known to have a higher CO reactivity at similar CO contents. TGA rate curves shows that prereduction of UMK ore occurred with two major distinctive steps. The first one was a combination of prereduction reactions and decomposition of carbonates with a peak temperature of 700 °C, and the second peak was the decomposition of calcite at 900 °C. The O/Mn ratio for UMK shows that prereduction is already completed prior to the second decomposition peak at 900 °C. In addition to prereduction reactions, Nchwaning is also characterized by an endothermic step which is decomposition of carbonates at 900 °C. Comilog ore produced the most fines followed by Nchwaning and lastly UMK on decrepitation. [ABSTRACT FROM AUTHOR]

Bench-scale electrowinning of electrolytic manganese dioxide was carried out using the manganese sulfate electrolyte generated through SO2 leaching of low-grade ferruginous manganese ore. The effect of different electrowinning process parameters on the current efficiency and specific energy consumption was studied. Results indicated that the current density, electrolyte temperature, and free acid concentration of electrolyte have a strong effect on the current efficiency and specific energy consumption. An electrolyte temperature of 90 ± 2 °C, current density of 9 mA/cm2, anode-to-cathode distance of 3 cm, electrolyte's initial pH of 6, and free acid concentration at 15 to 20 g/L were found to be the optimum conditions for EMD electrowinning. Under the optimized electrowinning conditions, a current efficiency of 93 pct and specific energy consumption of 1.4 kWh/kg EMD were realized. The produced EMD deposit was found to have a purity of 92.4 pct and a γ crystal structure. [ABSTRACT FROM AUTHOR]

The rare earth element (REE) composition of host rocks (dolomites, Neoproterozoic Pod"emsk Formation) and manganese ores (manganese oxides and carbonates of supergene zone) are studied. The Pod"emsk Formation is subdivided into the lower and upper subformations. The upper Pod"emsk subformation is characterized by the elevated manganese content and considered to be a Mn source for supergene ores of the deposit. Dolomites of the lower Pod"emsk subformation show no pronounced cerium anomalies (). They were formed in the absence or low concentrations of free oxygen in seawater. It is also probable that these dolomites experienced postsedimentary transformations, which could have resulted in the REE redistribution. Dolomites of the upper Pod"emsk subformation from a karst depression (positive Ce/*CeNASC anomaly) were formed under anoxic conditions, in a hydrodynamically weakly active shallow-marine environment. The elevated cerium concentrations in the dolomites could be also associated with the introduction of oxidized Ce into the sedimentation basin with river colloids. The positive europium anomaly in the dolomites of the Pod"emsk Formation ( = 1.22–2.16) could be related to the europium influx with subaquatic hydrothermal solutions (probably enriched in iron and manganese) or to the supply of europium with river runoff. Manganese was likely supplied in the Late Proterozoic sedimentation basin during the dolomite accumulation together with hydrothermal solutions and continental ablation. Manganese oxide ores show a sharp enrichment in HREE (by an order of magnitude), which likely occurred at the late (acidic) stage of supergene weathering as a result of LREE removal and HREE and yttrium retention in the weathering crust. [ABSTRACT FROM AUTHOR]

The ore–gas reactions in the prereduction zone in a ferromanganese furnace are largely decisive of the overall energy efficiency, carbon consumption, and climate gas emissions in ferromanganese production. An increased understanding of the prereduction zone is thus vital for optimization of the furnace operation. The ore–gas reactions are well known to be governed by kinetics rather than thermodynamics. The raw materials contain various amounts of both chemically bound and surface moisture when fed to the furnace, which may influence the reaction kinetics. This paper presents the investigation of the potential influence of moisture on the prereduction kinetics of two commercial manganese ores, i.e., Comilog and Nchwaning. TGA experiments were carried out by comparing dry and wet ore, as well as introducing H2(g) or H2O(g) to the CO–CO2 gas mixture. [ABSTRACT FROM AUTHOR]

Bryophyte communities have been widely used to monitor and assess heavy metal pollution in soil, air and water. However, the unique value of acrocarpous moss in monitoring environmental pollution and the harm of non-metallic sulfur to human health caused by carbonate manganese mining were seldom considered in previous studies. This study investigated the heavy metal and sulfur pollution level by soil and moss sample collection in Changgou manganese ore and its surrounding environment in the Zunyi area, Guizhou Province, China. By means of cluster analysis, diversity analysis, correlation analysis and redundancy analysis, the relationship between dominant moss communities and major pollutants were analyzed. The results showed that there were pollutants such as iron (Fe), manganese (Mn), cadmium (Cd), sulfur (S) and others in the 500 meters buffer zone centered on Changgou manganese ore. The ore sorting area and waste rock accumulation area were considered as the most seriously polluted, followed by the ore outlet area and ore transport line, at last the miners' living area and vegetable planting area were the least polluted. A total of 23 species of moss communities were identified in the Changgou manganese ore area, among which 9 were dominant, including Bryum blindii Bruch & Schimp. (Bry.bli), Weissia planifolia Dix (Wei.pla) — Bry.bli, Bryum caespiticium Hedw. (Bry.cae), Bryum pallescens Schleicher ex Schwägr. (Bry.pal), Didymodon longicostatus X. J. Li et Iwats (Did.lon), Weissia brachycarpa (Nees & Hornsch.) Jur. (Wei.bra), Trichostomum brachydontium Bruch. (Tri.bra), Bryum argenteum Hedw. (Bry.arg) Wei.bra and Bryum algovicum Sendt.ex Műll. Hal. (Bry.alg), all of which are from the acrocarp species. Bry.cae showed a strong tolerance to S, Did.lon to Fe, Bry.pal to Cd and Bry.bli to Mn. There was a significant correlation between the main polluting elements and the dominant bryophyte community (P<0.05), indicating a high biological indicator value. Together, our results can provide the scientific basis for soil pollution monitoring and human health risk assessment in carbonate manganese mining areas. [ABSTRACT FROM AUTHOR]

This study determines the thermodynamic regularities of the alloying and modification processes of steel with natural and man-made materials in an arc electric-steelmaking furnace and a ladle-furnace unit. The possibilities of the wide application of manganese ores of different compositions for alloying steel with a manganese content of up to 1% are also presented. Alloying takes place without using standard manganese alloys. For alloying, vanadium slag is used; when added, the steel is microalloyed with vanadium using carbon as the main reducing agent, and barium and strontium are also reduced. The use of these materials has been proven to improve the technical and economic indicators of the process of modifying steels and significantly improve the quality of the final metal products. Conclusions on the prospects for a significant expansion of the use of natural and man-made materials are drawn. [ABSTRACT FROM AUTHOR]

Manganese−based cathode materials are good alternatives to nickel-based layered cathodes in lithium-ion batteries due to the much cheaper cost of manganese ores. Coprecipitation is a popular method to produce precursor materials for lithium-ion batteries since its versatility enables the synthesis of a wide range of compositions with various architectures. In this study, spherical 2-µm to 4-µm-diameter binary Mn0.8Ni0.2CO3 and ternary Mn4/6Ni1/6Co1/6CO3 precursor materials were synthesized by tuning synthesis conditions including temperature, feeding mode and reagent quantity. The binary and ternary precursor materials were mixed and reacted with Li2CO3 at 800°C to obtain LiMn1.6Ni0.4O4 and Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials, respectively. LiMn1.6Ni0.4O4 had a discharge capacity of 132 mAh g−1 and exhibited excellent cycle life and voltage retention. On the other hand, 221 mAh g−1 discharge capacity was achieved with Li1.2Mn0.54Ni0.13Co0.13O2 , but it showed a fast capacity and voltage decay. A hybrid electrode made of 50:50 wt% of both cathodes yielded 166 mAh g−1 capacity and 3.95 V average discharge voltage with much reduced voltage decay and capacity fading rate, thereby mitigating each other's weakness in the process. [ABSTRACT FROM AUTHOR]

Manganese released from the piled manganese ore wastes is a great threat to the local ecosystem and human health. The mechanism and dynamic characteristics of manganese release from the manganese ore wastes were studied based on the static and dynamic experiments. The concentration of manganese in the leaching solution under the intensive state is twice that resulted from the static state; the manganese release from the waste rock increased with the increase of the solid-liquid ratio and reached 922.3 mg/L when the solid-liquid ratio was 1:5. When the particle size of waste rock was less than 180 μm, the release amount of manganese was the largest and reached 491.3 mg/L. When the pH was 7 and the rainfall intensity was 80 mL/h, the increase of leaching time contributed to the rapidly decreased amount of manganese released, and the leaching process reached equilibrium gradually. The cumulative release of manganese increased with the increase of rainfall duration. In the dynamic leaching process, the change of pH and EC of the leachate had nothing to do with the initial pH of leaching agent but has a close relationship with the hydrolysis of minerals in waste. According to the experimental results, it was found that the double constant equation model fitted the kinetic process of release process better. The purpose of this study was to provide a scientific basis for the assessment and control of manganese pollution in soil and groundwater in manganese mining area. [ABSTRACT FROM AUTHOR]

Ongoing development of manganese ore deposits in various countries and their treatment in special ferroalloys furnaces leads to continued environmental pollution by manganese compounds. At the same time, waste generated by companies is a valuable raw material that can be used to create marketable products. What is equally important is that low-cost and highly profitable production will contribute to the economic progress of regions and countries as a whole. That is of particular importance since toxic waste increases from 4 to 5 million tons each year. Several methods and technologies developed over the past decade may be proposed for the development, field demonstration, and implementation of the decontamination and use of metallic waste and contaminated soils. Among these is chemical-metallurgical enrichment of manganese, bacterial and chemo-bacterial leaching of manganese and arsenic, treatment of soils with ferrous and ferric sulfates and lime, phytoremediation, solidification, and stabilization of soils. Traditional industrial waste technologies are associated with significant energy costs, long process times, and the need for complex and expensive equipment. Waste generated in industrial operations is a valuable raw material and can be used to produce new marketable products. The study on the effectiveness of self-propagating high-temperature synthesis (SHS) methods, characterized by the simplicity of required equipment, the purity of the final product, and the high processing speed, is of high scientific and practical interest. The work presents technological aspects of obtaining ligature by the SHS method from finely dispersed particles of manganese ore wastes and dust obtained in silicomanganese production. Features and the main parameters to control the phase composition of synthesis products have been experimentally established, as well as the effect of overloads on cast ligature formation patterns and structure formation mechanisms. It has been demonstrated that valuable products can be obtained from finely dispersed waste through SHS metallurgy. In order to reduce the cost and increase the competitiveness of the manganese-containing ligatures obtained, a wide range of studies were conducted with various initial components. The economic feasibility of producing multi-component ligatures from the waste of manganese production has been established and justified. The proposed scientific approach will enable turning tens of millions of tons of ore and ferroalloy production wastes into industrial circulation globally and releasing millions of hectares of land littered with this waste to rehabilitate it. [ABSTRACT FROM AUTHOR]

The document titled "Prof. B. Krishna Rao (1941¿2023)" is an obituary published in the Journal of the Geological Society of India. It announces the passing of Prof. B. Krishna Rao, a retired Professor of Geology at Mysore University. Krishna Rao was born in Kakinada, Andhra Pradesh, and had a distinguished career in the field of economic geology. He made significant contributions to the understanding of the genesis of gold, copper, manganese, and magnesite deposits in Karnataka. Krishna Rao was also involved in collaborative research programs with international scientists and had a deep interest in the geochemistry of groundwater and seawater intrusion. He is remembered as a highly respected teacher and researcher in the geological community. [Extracted from the article]

The Ushkatyn-III deposit is located in Central Kazakhstan, 300 km west of Karaganda. It is ascribed to the weakly metamorphosed Atasu-type hydrothermal–sedimentary ore deposits. The Upper Devonian (D3fm2) carbonate sequence of this deposit comprises stratiform barite–lead, iron, and manganese orebodies. The study was focused on the iron– and manganese–bearing deposits. New data were obtained on the content of major (Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K, P), trace (Li, Be, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Cs, Ba, Hf, W, Tl, Pb, Th, and U), and rare-earth elements (REE) in all rocks of the ore-bearing unit. It is shown that all rocks, including host limestones, are enriched in Mn, As, Zn, Ba, and Pb, while normalization to aluminum revealed excessive Li, Be, Sr, Y, Mo, Cd, Sb, W, and Tl contents relative to the terrigenous part of sediment. REE variations point to a change of redox settings for accumulation of initial metalliferous sediments. Geological and geochemical data show that the genesis of the barite–lead, iron and manganese ores is related to the evolution of a single hydrothermal system. The ores were formed near or on the seafloor surface: the barite–lead ores are confined to venting sites on reefal buildups, while iron and manganese ores are formed from matter dispersed in the water column at some distance from hydrothermal vents. [ABSTRACT FROM AUTHOR]

Natural manganese ore (NM) is selected as a distinguished constructed wetland (CW) substrate for nutrient pollutants removal, however, the study on municipal wastewater treatment plant (WWTP) effluent treatment remains scarce. The current study was to investigate the sorption characteristics of NM and the removal efficiency of ammonium and phosphorus from one WWTP effluent in a simulated vertical flow NM constructed wetland (NM-VFCW). Results indicated that NM could effectively sorb ammonium and phosphorus within 24 h, and the desorption ratio was less than 7%. The sorption of ammonium and phosphorus enhanced when increasing the particle size of NM, but was not sensitive with temperature. The removal efficiencies for ammonium and phosphorus were 65% and 76% in NM-VFCW, which were 61% and 31% in gravel VFCW. The much higher removal efficiency for phosphorus was mainly attributed to the precipitation of phosphorus which was identified by the SEM and EDS spectrum. Therefore, the manganese ore sand is highlighted as a powerful substrate for simultaneous advanced removal of phosphorus and ammonium in constructed wetland systems. [ABSTRACT FROM AUTHOR]

Manganese ferrite spinel has been synthesized by using low grade manganese ore and ferric oxide as sources of manganese oxide and iron oxide through solid state reaction route by taking manganese and iron mole ratio of 1:2 respectively. The impact of sintering temperature on phase composition and particle size is investigated. Similarly, the impact of frequency on dielectric constant, dielectric loss, AC (alternating current) conductivity and tangent losses is also investigated. The results shows the presence of spinel structure manganese ferrite (MnFe2O4) as the major phase for the sample sintered at 1200 °C. It has been established that the crystallite size increase with rise in sintering temperature. The surface morphology of the sample sintered at 1200 °C show pyramidal and triangular shape grains. The dielectric constant (εʹ) and dielectric losses (εʹʹ) were observed to decrease with increasing the sintering temperature and frequency. Furthermore, the AC (alternating current) conductivity was found to rise with rise in applied frequency. On the other hand, the tangent losses falls considerably with rise in applied frequency. [ABSTRACT FROM AUTHOR]

Variations in energy efficiency and climate gas emissions in production of manganese ferroalloys are largely related to the solid-state reduction of the manganese ores used as raw material in the production. The gas-solid reduction is known to be dependent on the ore characteristics, making information on the factors governing the kinetics crucial. A reaction rate analysis of thermogravimetric data obtained for the reduction of Comilog and Nchwaning manganese ores in CO-CO2 atmosphere was performed. Experimental variables were CO partial pressure, ore particle size, temperature regimes (isothermal/non-isothermal), as well as heating rate for non-isothermal experiments. The effects of particle size, CO-concentration, and temperature on the reaction rates were quantified. It was found that the reduction rate of both ores was proportional to the inverse average particle size. Different sensitivities towards the CO-concentration in the gas feed was determined, where the rate of Comilog-ore was proportional to p CO 0.7 , and Nchwaning to p CO 1.5 . The activation energy of Comilog ore was estimated to be 17 kJ/mol, whereas 63 kJ/mol was found for Nchwaning ore. [ABSTRACT FROM AUTHOR]

The chemical and isotopic compositions of manganese carbonate and oxide ores and host dolomites of the Porozhinsk deposit are studied. Manganese carbonates are characterized by low values of δ13C (–19.0 to –8.4‰, PDB) and δ18O (8.8 to 27.3‰, SMOW). These data indicate the participation in their formation of the isotopically light carbon from oxidized organic matter, and the water of ore-depositing solutions was most likely meteogenic. The host dolomites (Pod"emsk Formation, Chapa Group) are characterized by a heavier isotopic composition of carbon (2.3‒2.6‰) and oxygen (22.5‒31.3‰) that are typical of marine sedimentary carbonates in the Late Proterozoic sedimentation basin. The simplest organisms played a significant role in the genesis of manganese ores. Microbial structures were preserved in manganese carbonates and oxides. [ABSTRACT FROM AUTHOR]

The reduction of higher manganese oxides to MnO in the prereduction zone of a ferromanganese furnace is largely decisive for the overall energy efficiency and climate gas emissions for the overall production process. Kinetics of the gas-solid reaction between the ore and CO(g) in the ascending furnace gas is dependent on the ore characteristics. The aim of this study was to elucidate the reduction steps during prereduction of two commercial manganese ores, Comilog and Nchwaning, in CO-CO2 atmosphere. Ore samples in various size fractions were exposed to isothermal and non-isothermal temperature regimes in various gas atmospheres utilizing a thermogravimetric furnace. Samples were characterized by titration, XRF, XRD, and SEM analyses. Comilog is a high oxygen ore, where the majority of the ore is constituted by various tetravalent manganese minerals. When heated in reducing atmosphere, MnO2-oxides were reduced to MnO in a single step at temperatures below 550 °C. The rate was dependent on the particle size and CO-concentration. When the temperature reached 550 °C, any present MnO2 rapidly decomposed to Mn2O3, which further continued to reduce to MnO. Nchwaning ore was found to be mainly constituted by Mn2O3-oxides, calcite and hematite. Manganese- and iron-oxides were found to reduce at similar temperature ranges, however the manganese oxide reduction was initiated prior to the iron oxides in smaller particle sizes (< 4 mm). Trivalent manganese oxides reduced to MnO in a single step, and the reduction of iron oxides subsided with the formation of wüstite. Carbonates decomposed at temperature range 800 °C to 1000 °C. Both ores obtained a promoted reaction rate with decreasing particle size and increased pctCO in CO-CO2 atmosphere. [ABSTRACT FROM AUTHOR]

High manganese steels with > 10% Mn offer a combination of high tensile strength and good ductility, two critical properties for automotive steels. Conventional routes to produce the Mn units used for steelmaking are energy- and capital-intensive. Therefore, a novel methane-based solid-state reduction process for manganese ore pellets is under investigation. It was found in preliminary tests that the reduction of ore pellets by methane was limited by gas transport to the pellet interior. To enhance the reducibility of Mn ore pellets, this study aimed at improving pellet porosity through adjustment of Mn ore powder particle size and the addition of limestone, which thermally decomposes to CaO and CO2. The change in compressive strength with an increase in pellet porosity was also studied. It was found that the increase in porosity as a result of limestone addition improves the reducibility of pellets and decreases the pellet strength. The effect of particle size on pellet reducibility was, however, more complicated because of the simultaneous change in the total surface area and sintering behavior of the particles. [ABSTRACT FROM AUTHOR]

The Ushkatyn-III deposit is located 300 km west of Karaganda (Central Kazakhstan). It is classified as a weakly metamorphosed Atasu-type hydrothermal-sedimentary ore deposit. Stratiform iron, manganese, and barite–lead orebodies occur in the Upper Devonian (D3fm2) carbonate sequence of this deposit. The Fe- and Mn-bearing rocks were studied. Iron ores are composed of hematite, calcite, and quartz. Manganese ores are divided into two (braunite and hausmannite) types. Braunite ores are composed of braunite, calcite, quartz, and albite; hausmannite ores are composed of hausmannite, rhodochrosite, Mn-calcite, tephroite (sometimes with sonolite and alleghanyite), and friedelite. The mineral composition of ores was formed during the burial of metal-bearing sediments containing oxides of Fe3+ and Mn3+/Mn4+. The nature and intensity of the postdepositional processes was controlled by the content of organic matter (OM) in initial rocks. Braunite ores formed under oxidizing conditions; hausmannite ores, under reducing conditions. The initial presence of OM is indicated by the carbon isotope composition in carbonates. High δ13Ccarb values (from –0.3 to 2.1‰) in hematite ores, braunite ores, and host limestones are close to those in the seawater bicarbonate precipitated as a part of biogenic calcite (e.g., shell fragments). At the same time, low δ13Ccarb values (average –12.3‰) in rhodochrosite and Mn-calcite from hausmannite ores indicate the influence of carbon from the OM buried in sediments. The general oxygen isotope composition in iron ores, manganese ores, and host rocks was determined by variations of the isotope ratio in the initial precipitates of 18O-rich calcite and 16O-rich Fe/Mn oxides. Conversion of the primary sedimentary Fe3+ and Mn3+/Mn4+ oxides to hematite, braunite, and hausmannite slightly changes the oxygen isotope composition of Fe–Mn minerals. Average values of δ18Otot determined in the hematite (1.7‰), braunite (14.8‰), and hausmannite (12.7‰) ores are close to those in the sedimentogenic iron (0‰) and manganese oxides (11.5‰). The oxygen isotope composition suggests that initial manganese oxides did not participate in the formation of carbonates in braunite ores. Average oxygen isotope composition of carbonates in these ores (δ18Ocarb 19.1‰) is close to that in host limestones (20.8‰). During the formation of hausmannite ores, in contrast, manganese oxides reacted with OM leading to the formation of rhodochrosite and silicates. Consequently, the light isotope oxygen in the starting oxides was fixed in carbonates (δ18Ocarb 15.9‰) and rocks in general (δ18Ototal 12.7‰). The oxygen isotope composition was not averaged during the formation of hausmannite ores even in the mineralogically similar aggregates in the adjacent rock layers. [ABSTRACT FROM AUTHOR]

The Steel Policy of India, 2017 aspires to achieve 300 million tonnes of steel-making capacity by 2030. This would translate into additional consumption of manganese and chrome ore other than iron ore as essential raw material for steel making. Similarly, ferro-alloys are one of the important inputs in the manufacture of alloys and special steel. The growth of the ferro-alloy industry is, thus, linked with the development of the iron and steel industry. With the abundant resources, there is huge potential of manganese ore and chromite and ferro-alloy industry in India. India has huge resources of manganese and chrome but the import of these minerals is increasing. Due to limited availability of high-grade manganese ore and chromite reserve in the country, lower grade ore has to be upgraded by beneficiation. [ABSTRACT FROM AUTHOR]

It has been 36 years since ISO 4298:1984 was published, yet the role of sodium pyrophosphate in the oxidation of manganese(II) by potassium permanganate in this standard has not been fully recognized. The sample and reagent dosages exceed the actual detection needs, which creates challenges in the test operation and waste liquid treatment. In this study, a more scientific expression for the principle and reaction and the dosage of pyrophosphate in ISO 4298:1984 are discussed. The pyrophosphate ligand is involved in the oxidation of manganese(II) by potassium permanganate, and plays a role in preventing Mn(II) precipitation or Mn(III) dismutation during the whole reaction. The most appropriate amount of saturated sodium pyrophosphate is 150 mL for the test of manganese ores and concentrates with manganese content from 15% to 60%. The method developed by reducing sample size and reagent consumption was evaluated with ten certified reference materials, showing high accuracy and meeting the analytical performance requirements. These results can provide technical support for the revision of ISO 4298:1984. [ABSTRACT FROM AUTHOR]

Manganese is considered a relatively rare metal as concentrations of it in ore of commercial importance are geographically limited. In nature, manganese is found in the form of oxides, carbonates, and silicates. Manganese ores are complex in the sense that they not only consist of a complex oxide mineral assemblage but these minerals are also very finely inter-grown. South Africa accounts for 74% of the world's identified manganese resources and 32% of the world's reserves. The paper presented here describes in more detail the resource and the complex mineralogy of the ore body, as well as the existing and potentially new processing technologies available from minerals processing and pyrometallurgical perspectives. [ABSTRACT FROM AUTHOR]

A novel circulation process of electrolytic manganese metal (EMM) production with low-grade manganese oxide ores (LGMO) and high-sulfur manganese ores (HSMO) was studied and developed. The unit operations mainly include dissolution of LGMO, purification of leach liquor and electrolysis for EMM preparation. Based on the theoretical thermodynamic analysis, a reductive roasting-acid leaching process for utilizing LGMO using HSMO as reductant was investigated. The leaching efficiency of Mn and Fe could get to 97.30% and 17.50% with conditions set as following, which have all been verified through a series of experiments: the material ratio of 1.67:1 (mass ratio of HSMO to LGMO, w/w), roasting temperature of 600 °C for 60 min, L/S ratio of 5:1, stirring speed of 150 rpm, sulfuric acid concentration of 1.0 mol/L and the leaching temperature of 60 °C for 35 min. Meanwhile, the reduction roasting-acid leaching process applies to the Mn extraction for assorted manganese dioxide ores in general. Furthermore, the leach liquor was purified in two steps, and following a scale-up electrolysis process was implemented to prepare EMM from the purified liquors. The uniform and dense α-Mn with bcc crystal structure, meeting the requirement of metallurgical industry standard (YB/T 051-2003), could be stably produced in 9-day incessant ongoing test. [ABSTRACT FROM AUTHOR]

The dephosphorization of a manganese oxide concentrate with an increased phosphorus content is experimentally studied by blowing a manganese-containing melt with carbon monoxide in the temperature range 1400–1560°C. The reaction of gaseous carbon monoxide with phosphorus oxide dissolved in a manganese-containing melt begins to develop. The dephosphorization leads to a substantial decrease in the phosphorus content in a manganese-containing melt. A new method for the dephosphorization of manganese-containing products is developed. The method has no analogs and makes it possible to involve domestic manganese ores in production. [ABSTRACT FROM AUTHOR]

A comprehensive study of the manganese ore deposits of Banswara manganese belt (23°10′-23°20′N to 74°15′-74°25′E) in the Banswara district, Rajasthan, has shown a characteristic assemblage of manganese ore minerals. The manganese ore deposits are associated with Aravali phyllite, schist, quartzite and limestone, etc., and occur within a narrow linear belt trending NW-SE. These meta-sediments hosted manganese ores that belong to the Aravalli Supergroup are of Paleo-Proterozoic age. The mineralogical investigation of a number of polished blocks showed the dominance of braunite accompanied by pyrolusite and cryptomelane. A number of mineral assemblages are recommended. The significant ore textures are, banding, replacement and colloform, while other textures identified are veined, granular, brecciated, relict, open space, and mutual boundary relationship. The micro-structural and textural relations are discussed and interpreted to disclose the paragenetic history of ore minerals crystallization, which are usually divided into primary (metamorphic) and secondary (supergene) ores. The aim of this study is to determine the presence of manganese oxides/silicates ore minerals, and to comprehend the sequence of their crystallization. This study is further correlated to a geochemical background of these Mn ores to depict the mode of their origin and depositional settings. The present study has come to the conclusion that the dominance of braunite, banded texture and conformable relations with the associated rocks, indicates the original deposition of syngenetic manganiferous pelitic-psammitic sediments, which, were regionally metamorphosed to form a low grade primary ore deposits but the dominance of pyrolusite, and cryptomelane, along with other secondary manganese ore minerals also pointed out a subsequent chemical weathering and leaching of these earlier formed primary ore, and silicate minerals, resulting in precipitation, and deposition of high grade secondary ore deposits of later origin. [ABSTRACT FROM AUTHOR]

There are many challenges in the task of predicting ore deposits from big data repositories. The data are inherently complex and of great significance to the intervenient spatial relevance of deposits. The characteristics of the data make it difficult to use machine learning algorithms for the quantitative prediction of mineral resources. There are considerable interest and value in extracting spatial distribution characteristics from two-dimensional (2-d) ore-controlling factor layers under different metallogenic conditions. In this paper we undertake such analysis using a deep convolutional neural network algorithm named AlexNet. Training on the 2-d mineral prediction and classification model is performed using data from the Songtao–Huayuan sedimentary manganese deposit. It mines the coupling correlation between the spatial distribution of chemical elements, sedimentary facies, the outcrop of Datangpo Formation, faults, water system, and the areas where manganese ore bodies are present, as well as the correlation among different ore-controlling factors by employing the AlexNet networks. By comparing the training loss, training accuracy, verification accuracy, and recall of models trained by different scales of grids and different combinations of ore-controlling factor layers, we further discuss the most appropriate scale division and the optimal combination of ore-controlling factors to make the model achieve its strongest robustness. It is found that the prediction performance of AlexNet networks reaches its peak when selecting a grid division of 200 pixels × 200 pixels (the actual distance is 10 km × 10 km) and inputting the distribution layers of 21 chemical elements maps, lithofacies–paleogeographic map, formation and tectonic map, outcrop map of Datangpo Formation, and water system map. The training loss, training accuracy, verification accuracy, and recall of the optimal model are 0.0000001, 100.00%, 86.21%, and 91.67%, respectively. The proposed method is successfully applied to the 2-d metallogenic prediction in Songtao–Huayuan study area. And five metallogenic prospective areas from A to E are delineated with large probability for potential ore bodies. [ABSTRACT FROM AUTHOR]

Arsenic contamination of drinking water is a serious water quality problem in many parts of the world. In this study, a low-cost manganese oxide ore from Vietnam (Vietnamese manganese oxide (VMO)) was firstly evaluated for its performance in arsenate (As(V)) removal from water. This material contains both Mn (25.6%) and Fe (16.1%) mainly in the form of cryptomelane and goethite minerals. At the initial As(V) concentration of 0.5 mg/L, the adsorption capacity of original VMO determined using the Langmuir model was 0.11 mg/g. The modified VMOs produced by coating VMO with iron oxide (Fea-VMO) and zirconium oxide (Zra-VMO) at 110 °C and 550 °C achieved the highest As(V) adsorption capacity when compared to three other methods of VMO modifications. Langmuir maximum adsorption capacities of Fea-VMO and Zra-VMO at pH 7.0 were 2.19 mg/g and 1.94 mg/g, respectively, nearly twenty times higher than that of the original VMO. Batch equilibrium adsorption data fitted well to the Langmuir, Freundlich, and Temkin models and batch kinetics adsorption data to pseudo-first order, pseudo-second order, and Elovich models. The increase of pH progressively from 3 to 10 reduced As(V) adsorption with a maximum reduction of 50–60% at pH 10 for both original and modified VMOs. The co-existing oxyanions considerably weakened the As(V) removal efficiency because they competed with As(V) anions. The competition order was PO43− > SiO32− > CO32− > SO42−. The characteristics of the original and modified VMOs evaluated using SEM, FTIR, XRD, XRF, surface area, and zeta potential explained the As(V) adsorption behaviour. [ABSTRACT FROM AUTHOR]

Numerous phosphorite occurrences are located among the Riphean–Early Cambrian rocks of the Khingan Group (Lessr Khingan, JAO). They are associated spatially and genetically with uranium, iron, and manganese ore occurrences. The phosphorites of the Gremuchy occurrence are enriched in rare-earth elements (REE) and yttrium (up to 813.58 g/t), uranium (up to 52.23 g/t), and gold (up to 17.03 g/t), and can be considered as a complex of phosphorus–uranium–gold–rare-earth ores. REE-rich fluorapatite is the main concentrator of phosphorus in these rocks. REE do not form their own minerals, while gold, silver, and platinum are found as microinclusions. The concentrations of phosphorus, radioactive, and rare-earth elements are positively correlated with the organic carbon content, which supports their coprecipitation from seawater enriched in rare and rare-earth elements supplied by hydrothermal vents on the surface of the slope of seamount volcanoes. [ABSTRACT FROM AUTHOR]

Manganese ore is an important mineral having a strategic role in the development of the national economy and society. In this study, the dielectric properties, heating curve, crystal structure, and reduction ratio of a low-grade pyrolusite were investigated. The dielectric constant, dielectric loss factor, and loss tangent coefficient of low-grade pyrolusite at room temperature were evaluated using the resonant cavity perturbation method, yielding values of 5.854, 0.146, and 0.0249, respectively. Owing to the excellent microwave absorption properties of low-grade pyrolusite with 10% coal (22 g), it could be heated to a temperature of 800°C within 200 s. X-ray diffraction results confirmed that MnO2 was partially transformed into MnO at 450°C, while, at 650°C, no diffraction peak of MnO2 was observed. At a reduction temperature of 550°C, a reduction ratio of MnO2 to MnO of 96.65% could be achieved within a holding time of 50 min. This study demonstrates that the microwave carbothermal reduction of a low-grade pyrolusite is efficient, and thus could promote the clean production and sustainable development of the manganese industry. [ABSTRACT FROM AUTHOR]