Manganese Oxide Ore Research Articles

A Green Cyclic Leaching Process for Low-Grade Pyrolusite via a Recyclable Fe(II) Reductant

The low-cost Fe(II) reductants used in the leaching of pyrolusite usually cause high concentrations of iron ions in the leaching solution, which are difficult to treat and recover. Herein, a green cyclic leaching process for pyrolusite with recycling and reusing of Fe(II) reductants was developed. Sodium sulfide was introduced to reduce and precipitate iron ions in the leaching solution. Ep-H diagrams show that Fe3+ can be reduced to Fe2+ by S2− and form a precipitate with the high efficiency of 93.09%. Since the main component of the precipitate was ferrous disulfide with reducibility, it was used as a reducing agent for low-grade manganese oxide ores. A total of 97.96% of the manganese was highly reductively leached by the obtained precipitate of 0.28 g·g−1 ore. Furthermore, the leaching efficiency was almost unchanged after five iterations of cyclic experiments. The cyclic leaching process enables the efficient leaching of manganese and the recycling of iron, which provides a green and economic method for the efficient utilization of low-grade pyrolusite resources.

An efficient and clean method for the selective extraction and recovery of manganese from pyrolusite using ammonium sulfate roasting-water leaching and carbonate precipitation

Manganese is a fundamental metal raw material that plays a crucial role in sustainable economic and social development. With the battery industry undergoing rapid advancements in the recent years, there has been a consistent rise in the demand for manganese. This study proposes a new scheme for selectively extracting manganese from pyrolusite by the sulfation roasting-water leaching process, while the iron is enriched in the leaching residues in the form of Fe2O3. With a 1.5:1 mass ratio of ammonium sulfate to pyrolusite, a roasting temperature of 650 °C, and a duration of 120 min, the extraction efficiency of manganese was observed to be 96.15%, while iron extraction was only 1.45%. And the leaching residues containing mainly 54.62% SiO2 and 36.10% Fe2O3 were obtained, which could be enriched with iron by flotation. Subsequently, the purified leaching solution was subjected to manganese precipitation using ammonium bicarbonate. Under optimal conditions, the precipitation efficiency of manganese was 99.63%, and the manganese carbonate products were obtained with a particle size of approximately 1–1.5 μm spherical structure, which met the requirements of the industrial manganese carbonate quality standard (HG/T4203-2011). The mechanism studies have proven that MnO2 in pyrolusite was first converted to (NH4)2Mn2(SO4)3 and then to MnSO4, while Fe2O3 was converted to (NH4)3Fe(SO4)3, NH4Fe(SO4)2, Fe2(SO4)3 in turn and finally decomposed to Fe2O3. The ammonia produced during the roasting process can be absorbed to regenerate ammonium sulfate products, and the filtrate from the manganese precipitation can also be crystallized by evaporation to obtain ammonium sulfate products, both of which can be used in the roasting process to reduce production costs. The process of this study proposed is simple and does not require any strong acid or alkali reagents. It offers high efficiency, is environmentally friendly, and is easy to operate, thus providing a new idea and scheme for the multi-component resource utilization of manganese oxide ore.

Extraction of various valuable elements from oceanic manganese nodules using coal gasification slag via reduction roasting-acid leaching process

In line with the concept of coal gasification slag treatment and marine mineral exploitation, this research proposed a residual carbon roasting-acid leaching process to extract various valuable metals from oceanic manganese nodules. The residual carbon obtained from coal gasification coarse slag was enriched via gravity separation without chemical treatment, and this carbon-high product served as an inexpensive reducing agent. The feasibility of carbon-high reduction of oceanic manganese nodules was explored using a thermogravimetric-mass spectrometric coupling system and thermodynamic analysis. The influence of mass ratio, roasting time, and roasting temperature on the reduction effect of oceanic manganese nodules was examined, and optimal conditions were determined through orthogonal tests. The results demonstrated that under the optimized conditions, the leaching rate of Mn exceeded 98%, and that of Cu, Co, and Ni exceeded 96%. The reduction and leaching processes were elucidated at the crystal scale through various ways. Finally, a comprehensive process flow diagram was summarized for the extraction of various valuable metals from oceanic manganese nodules using the residual carbon roasting-acid leaching process. This research will pave the way for the design of cost-effective and sustainable roasting reductants and reduction roasting processes for manganese oxide ores, contributing to economic and environmental benefits.

High-efficiency and environment-friendly separation and recovery of manganese from braunite via the ammonium sulfate roasting-water leaching process: Behavior and mechanism

Manganese ore is a key raw resource for the development of new energy, new materials, and other emerging industries, as well as a basic raw material for the steel industry. As resources of the main high-grade pyrolusite are depleting, it is of strategic importance to develop and utilize other manganese oxide ores. This paper proposed the two-stage ammonium sulfate roasting-water leaching process for high-efficiency and environment-friendly separation and recovery of manganese from braunite ((Mn2O3)3MnSiO3). The first-stage was sulfation roasting, which could convert Mn and Fe in braunite into (NH4)2Mn2(SO4)3, (NH4)3Fe(SO4)3, NH4Fe(SO4)2 and Fe2(SO4)3; the second-stage was selective roasting, that could decompose (NH4)2Mn2(SO4)3 into MnSO4, and decompose (NH4)3Fe(SO4)3, NH4Fe(SO4)2 and Fe2(SO4)3 into Fe2O3. Under the optimum leaching conditions, the leaching efficiency of Mn reached 97.79%, while the leaching efficiency of Fe was only 1.52%, and a solution with a concentration of 93.36 g/L for Mn was obtained. The NH3 volatilized during roasting was absorbed by the water solution to get an ammonia solution which was used to precipitate Mn from the leaching solution. The precipitation efficiency of Mn was 99.48% under optimal conditions. Manganese oxide products such as Mn3O4 or Mn2O3 could be obtained by drying and calcining Mn-rich precipitates. The final filtrate was neutralized with H2SO4 and then evaporated and crystallized to give an (NH4)2SO4 product, enabling the recycling of ammonia. The process proposed in this paper is not limited to the treatment of braunite, but can also be applied to the processing of other manganese oxide ores and has a wide application potential. Compared to the traditional reduction roasting-acid leaching process, this process is more efficient and environmentally friendly.

In-process control of manganese dithionate in the manganese ore-based wet flue gas desulfurization coupled with efficient manganese leaching

Manganese ore-based wet flue gas desulfurization (MFGD) is a resourcing technology capable of simultaneously reutilization flue gas sulfur dioxide (SO2) and green, low-carbon manganese leaching. However, the by-product manganese dithionate (MnS2O6) greatly affects the use of desulfurization liquid. In this study, the iron introduced MFGD process to achieve the in-process control of MnS2O6 was proposed and systematically studied. The results revealed that the Fe(III) greatly enhanced the MnS2O6 degradation by manganese dioxide (MnO2), which works principally as an oxidant, and generates certain hydroxyl oxidize iron (FeOOH) to promote the MnS2O6 degradation. Kinetic studies revealed that the Fe(III) enhanced MnS2O6 degradation by manganese oxide ore (MnOO) occurred mainly on the surface of solid, and the apparent activation energy (Ea) was reduced to 43.56 kJ mol−1. The Fe(III) could be also incorporated into the MFGD process to achieve the in-process control of MnS2O6. According to the operational experiments, 5.00 g L−1 of Fe(III) in the MnOO slurry could reduce the MnS2O6 in the desulfurization liquid from 5.34 g L−1 to 1.75 g L−1 and without any noticeable negative effect. This study provides an applicable option for the low-cost and simple control of MnS2O6 of the MFGD technology, and it will also support the utilization of the low-grade manganese ore.

Degradation performance of high-concentration coking wastewater by manganese oxide ore acidic oxidation.

The degradation of coking wastewater using a manganese oxide ore acidic oxidation was investigated. This work was performed in three stages. Firstly, the advantageous degradation conditions were measured by the degradation tests, and under the optimal conditions percentage degradation was obtained of 91.6% chemical oxygen demand measured by potassium dichromate oxidation (CODcr), 94.7% total nitrogen (TN), 98.3% phenols, 98.2% fatty acid, 89.5% tar, and 98.9% sulphide for the oxidized effluent, simultaneously cogenerating a Mn2+concentration of 46.2 g/L for Mn-electrolytic stock solution. Secondly, the transformation analysis of the special chemical group of coking wastewater contaminants illustrated that the employment of manganese oxide ore generated the degradation of low and high molecular weight organics, especially causing polymers to break down into oligomers. Thirdly, the electrochemical characteristics of the interface between wastewater and ore revealed that the contaminant degradation of coking wastewater greatly depended on the oxidation capacity of the surface oxide species, involving a simple answer to the MnO2 oxidation for small-molecule organic materials and a strengthening response to the MnO·OH oxidation for high-weight molecule organic substances. The treatment of coking wastewater using the Mn-oxide ore acidic oxidation process is an effective and value-added method, which is particularly applicable to high-concentration coking wastewater.

Enhanced microbial nitrate reduction using natural manganese oxide ore as an electron donor

Nitrate contamination of groundwater is a global problem. Enhanced biological nitrate reduction by liquid organics combined with low-cost natural materials (as electron donors) can cost-effectively remove nitrate from groundwater. Dissolved Mn(II) as an electron donor has been thoroughly investigated to support microbial nitrate reduction. However, most Mn in soil and sediments is in solid form, and the ability of solid-phase natural manganese oxide ore (NMO) as electron donor and for supporting microbial nitrate reduction is unknown. Therefore, a microcosm experiment was conducted to bridge this gap in knowledge. The results demonstrated that microbial nitrate reduction (mainly converted to nitrite) was enhanced by NMO (rich in cryptomelane). The electrochemical and X-ray photoelectron spectroscopy analyses suggested that NMO may be oxidized by microbial metabolism. Illumina Miseq sequencing results indicated that Acidovorax spp. played a crucial role in NMO-supported nitrate reduction. Further Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analyses indicated that bacterial extracellular electron transfer may be one of the mechanisms for the microbial NMO oxidation. The results of our study highlight the potential importance of NMO in nitrate reduction in the natural environment and may pave the way for NMO-assisted technology for nitrate removal from groundwater with less usage of organic electron donors.

THE EFFECT OF PH VARIATIONS ON THE STRUCTURE OF THE MnFe2O4/PS NANOCOMPOSITE LAYER AS SELF CLEANING

Manganese is a metal element found in group VII, has an atomic weight of 54.93u, with a boiling point of 20320˚C, while the melting point is 12470˚C, and has a reddish-gray color. Iron (III) oxide (Fe2O3) or also known as hematite or maghemite iron ore, iron hematite (α – Fe2O3) is a simple oxide which has a hexagonal (rhombohedral) structure and has the R3c space group. Manganese was used as reinforcement in this research, while the matrix used was polystyrene. In this study, 5 variations of pH MnFe2O4/PS, namely 5,6,7,8 and 9 nanocomposites were synthesized using the spin coating method with manganese oxide (MnO2) and iron ore (Fe2O3) precursors. The composite gel is dropped on the glass substrate then the drying process is carried out in an oven. MnFe2O4/PS nanocomposites were characterized using X-Ray Diffraction (XRD). giving acid and alkaline solutions affects the size of the crystals, when adding a base (25% Na4OH) the crystal size becomes small while when the acid is added (100% CO3COOH) the crystal size is larger. : pH 8: pH 9 an increase in crystal size and grain size occurs.

Removing arsenate from water using modified manganese oxide ore: Column adsorption and waste management

There is a need to remove arsenic (As) in drinking water supplies by simple and cost-effective techniques. A column adsorption study was conducted to remove As(V) from water employing an iron (Fe) and zirconium (Zr) grafted Vietnamese manganese oxide ore (Fea-VMO and Zra-VMO). At a flow rate of 0.15 L/h, the bed volumes of water (As(V) concentration 0.1 mg/L) treated by Zra-VMO and Fea-VMO to produce water with As(V) concentration below the WHO guideline concentration (10 μg/L) were 6 and 8 times higher than for VMO, respectively. An increase in influent As concentration increased the adsorption capacity, but the increase of flow rate reduced the adsorption capacity. The maximum adsorption capacities derived from the Thomas model for VMO, Fea-VMO, and Zra-VMO at an influent concentration of 0.25 mg As(V)/L and flow rate of 0.15 L/h were 0.151, 1.145, and 0.925 mg/g, respectively. These values fell when influent As concentration decreased or the flow rate increased. Solidification/stabilisation method was applied to immobilise As(V) in the exhausted absorbent wastes by replacing 5, 10, 15, and 20 % of sand in a sand/cement concrete mixture by the adsorbent waste. This solidified material had satisfactory compressive strength, rapid chloride penetrability test, and volume of permeable voids, which indicated the material had good stability, making it suitable for use as a building material in construction work. The As(V) leaching from these materials, as measured by Method 1313 of the Leaching Environmental Assessment Framework of USEPA, proved to be very negligible.

Major, trace and rare earth element (REE) geochemistry of the Oligocene stratiform manganese oxide-hydroxide deposits in the Nikopol, Ukraine

The Nikopol manganese deposit is situated in the west and north of Nikopol, Ukraine and one of the world's largest deposits among the sedimentary manganese deposits. The Nikopol Oligocene basin consists of two structural stages, Precambrian crystalline basement rocks and sedimentary cover rocks (Cretaceous to Quaternary). Nikopol Ore horizon is traced in a thickness varying from several cm to 4.5 m and a single stratum from the west to the eastwards to about 250 km. Nikopol manganese ore horizon was separated to three different units; carbonate ore, mixed carbonate-oxide ore, and oxide ore. The main minerals of supergene oxidation zone in Nikopol manganese deposits are: manganite, pyrolusite, todorokite, cryptomelane, birnessite, rancieite. The manganese oxide-hydroxide ores were analyzed for major oxides using ICP-AES and, trace and rare earth elements (REE) using ICP-MS. The mean major oxide contents of the manganese ores are 40.7 wt% MnO, 4.1 wt% Fe2O3, 15.6 wt% SiO2, 4.17 wt% for Al2O3, and 7.1 wt% for CaO. The average Mn/Fe, Co/Ni, Co/Zn, and Zr/Hf ratios in the Nikopol manganese deposit are 25, 0.54, 1.15, and57, respectively. The total REE contents are between 60 and 197 ppm, with a mean of 108 ppm. The PAAS-normalized REE patterns of the Nikopol manganese oxide ores have similar trends and show MREE (middle rare earth element) and HREEs (heavy rare earth element) enrichments. The Ce/Ce* values of manganese oxide-hydroxide ores collected from the study area vary from 0.88 to 1.43, with the mean of 1.16. Most of manganese samples have positive Ce anomalies except for a few samples, indicating that ore-forming rocks were primarily marine chemical or biogenic deposit. The Eu/ Eu* anomalies of the manganese oxide-hydroxide ores are close to 1 with a range of 0.68 to 1.12 (mean: 0.96). The Y concentrations vary from 9.1 to 47.1 ppm, with an average of 18.2 ppm and show negative Y anomalies, except for three samples. The Pb isotope ratios are 19.0 for 206Pb/204Pb, 15.7 for 207Pb/204Pb and 39.4 for 208Pb/204Pb isotopes. All these data indicate that the Nikopol manganese oxide-hydroxide ores formed rapidly within oxic/suboxic seawater as reflected by Ce anomalies close to 1 in compared to similar environments, low-oxygen fugacity in source of the hydrothermal fluids, volcanogenic input or hydrothermal contributions to seawater, and high Co, Ni, Cu, Sr, Ba and As and low V, Rb, Nb, Hf, U, Th, Pb and Zn values. Also, our results point out that the metals were transported from both a hydrothermal source in deeper water (chemical discrimination diagrams) and terrestrial sources (Pb isotopic data). The metals formed to the Mn-oxide ores syngenetically likely came from water depths deeper than the area where the carbonate-ore deposits formed.

Microhardness characterisation of manganese ore minerals – Implications for downstream processing

Manganese oxide, silicate and carbonate ores are mostly mined as feedstock for steelmaking where Mn is largely added as ferroalloy, but they are also used for battery and to a lesser extent fertiliser and pigment production. The physical, mineralogical and textural properties of manganese ore minerals are known to influence their thermal properties and thus their high temperature behaviour during sintering or alloy production.Microhardness testing using the Vickers indenter is a potentially valuable characterisation technique to correlate the physical and optical properties of Mn ore minerals with their mineral chemistry and texture when used in conjunction with electron probe microanalysis (EPMA) and helium pycnometry. Microhardness values can also inform potential beneficiation pathways for lower grade Mn ores and/or assist in the prediction of lump: fines ratios during mine planning.This study provides the results of microhardness testing of Mn ore minerals from several different Mn ore types with variable mineralogy and texture. The data indicates that there is a clear link between mineral microhardness and micro- to nano-scale porosity and microcrystallinity, leading to potentially large variations in microhardness for some common Mn ore minerals. For example, cryptomelane with lower reflectivity, interpreted as having higher nano- to micro-porosity and/or differences in microcrystallinity, has significantly lower microhardness (mean 267 kg/mm2) than cryptomelane with higher qualitative reflectivity (mean 629 kg/mm2).EPMA conducted on mineral grains subjected to microhardness testing showed microhardness values did not vary systematically with changes in mineral chemistry but did vary with total element content as determined by EPMA. Low analytical totals were a de facto semi-quantitative measurement of mineral nano- to micro-porosity due to likely beam splitting/dispersion on more microporous samples identified during optical microscopy. Although there was no systematic link seen between microhardness and tetravalent Mn mineral element chemistry in this instance (e.g., K in cryptomelane), cryptomelane with lower reflectivity has lower Mn contents and higher contents of minor elements such as Fe, Al and Si.

Hydrometallurgical recovery of manganese, gold and silver from refractory Au-Ag ore by two-stage reductive acid and cyanidation leaching

In this study, a refractory Au-Ag ore from Beiya (Yunnan, China) was characterised and the occurrence states of low-grade gold and silver were clarified. The results revealed that the gold in the ore mainly occurred as visible native gold, which can be leached easily via cyanidation, whereas the visible silver minerals occurred as native silver, acanthite, chlorargyrite, acanthite, pyrargyrite, andorite and polybasite. Nevertheless, most of the silver occured as invisible silver in manganese oxide ore with the form of isomorphs and could not be leached via direct cyanidation. A pretreatment of reductive acid leaching using sodium sulphite as a reductant successfully leached the manganese and liberated the silver, which was very beneficial for the cyanidation of silver. The manganese was enriched in the leaching solution at a concentration of 16.51 g/L with an average leaching percentage of 70.27% after five-stage cyclic reductive acid leaching under optimised conditions of 1.0 mol/L of H2SO4, 20 g/L of Na2SO3, a liquid-solid ratio of 5:1, and stirring speed of 300 r/min at room temperature (28 ± 1 °C) for 1.0 h. We could easily recover 99.90% copper and 99.80% manganese from the leaching solution via iron powder reduction and sodium carbonate precipitation. Following the leaching of manganese, the cyanidation leaching percentages of gold and silver were to 87.37% and 80.19% respectively. In summary, we developed a novel process for the hydrometallurgical recovery of manganese, gold, and silver from refractory Au-Ag ore.

A Novel Circulation Process to Effectively Produce Electrolytic Manganese Metal (EMM) with Low-Grade Manganese Oxide Ores and High-Sulfur Manganese Ores

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.

Removing arsenic from water with an original and modified natural manganese oxide ore: batch kinetic and equilibrium adsorption studies.

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 0.5mg/L, the adsorption capacity of original VMO determined using the Langmuir model was 0.11mg/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 2.19mg/g and 1.94mg/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.

Sulfur resource recovery based on electrolytic manganese residue calcination and manganese oxide ore desulfurization for the clean production of electrolytic manganese

Abstract An environmentally friendly and resource-conserving route to the clean production of electrolytic manganese was developed, in which the electrolytic manganese residue (EMR) was initially calcined for cement buffering; then the generated SO2-containing flue gas was managed using manganese oxide ore and anolyte (MOOA) desulfurization; at last, the desulfurized slurry was introduced to the electrolytic manganese production (EMP). Results showed that 4.0 wt% coke addition reduced the sulfur of calcined EMR to 0.9%, thereby satisfying the cement-buffer requirement. Pilot-scale desulfurization showed that about 7.5 vol% of high SO2 containing flue gas can be cleaned to less than 0.1 vol% through a five-stage countercurrent MOOA desulfurization. The desulfurized slurry had 42.44 g·L−1 Mn2+ and 1.92 g·L−1 S2O62−, which was suitable for electrowinning after purification, and the purity of manganese product was 99.93%, satisfy the National Standard of China YB/T051-2015. This new integrated technology fulfilled 99.7% of sulfur reutilization from the EMR and 94.1% was effectively used to the EMP. The MOOA desulfurization linked the EMP a closed cycle without any pollutant discharge, which promoted the cleaner production of EMP industry.

Microbially Mediated Ore-Forming Processes and Cell Mineralization.

Sedimentary black shale-hosted manganese carbonate and oxide ores were studied by high-resolution in situ detailed optical and cathodoluminescence microscopy, Raman spectroscopy, and FTIR spectroscopy to determine microbial contribution in metallogenesis. This study of the Urucum Mn deposit in Brazil is included as a case study for microbially mediated ore-forming processes. The results were compared and interpreted in a comparative way, and the data were elaborated by a complex, structural hierarchical method. The first syngenetic products of microbial enzymatic oxidation were ferrihydrite and lepidocrocite on the Fe side, and vernadite, todorokite, birnessite, and manganite on the Mn side, formed under obligatory oxic (Mn) and suboxic (Fe) conditions and close to neutral pH. Fe- and Mn-oxidizing bacteria played a basic role in metallogenesis based on microtextural features, bioindicator minerals, and embedded variable organic matter. Trace element content is determined by source of elements and microbial activity. The present Urucum (Brazil), Datangpo (China), and Úrkút (Hungary) deposits are the result of complex diagenetic processes, which include the decomposition and mineralization of cell and extracellular polymeric substance (EPS) of Fe and Mn bacteria and cyanobacteria. Heterotrophic cell colonies activated randomly in the microbialite sediment after burial in suboxic neutral/alkaline conditions, forming Mn carbonates and variable cation-bearing oxides side by side with lithification and stabilization of minerals. Deposits of variable geological ages and geographical occurrences show strong similarities and indicate two-step microbial metallogenesis: a primary chemolithoautotrophic, and a diagenetic heterotrophic microbial cycle, influenced strongly by mineralization of cells and EPSs. These processes perform a basic role in controlling major and trace element distribution in sedimentary environments on a global level and place biogeochemical constraints on the element content of natural waters, precipitation of minerals, and water contaminants.

Mechanisms of dry flue-gas desulfurization using natural manganese oxide ores

The mechanisms of flue-gas desulfurization using high and low-grade natural manganese oxide ores were comparatively studied. Both manganese oxide ores exhibit good desulfurization capabilities with SO2 content in the effluents less than 30 ppm, but the low-grade ores show the much better desulfurization capability. XRD and SEM/EDS results reveal that the MnO2 absorbs the SO2 to convert to MnSO4. The SO2 give prior to react with the surface MnO2 and the produced MnSO2 enriched on the surface leads to the gradually decrease of the SO2 removal rate during desulfurization process. The better desulfurization capability of the low-grade ores is ascribed to the more dispersive MnO2 due to the poriferous/lax internal tunnel structure, and the embedded inert SiO2 shows better support effects to avoid pore structure blocking, which is favorable for enhancing the diffusion of the SO2 and desulfurization reaction process. This study is of significance in the comprehensive utilization of the low-grade natural manganese oxide ores, environmental protection and even the preparation of the desulfurization catalyst with MnO2.

Novel hydro-electrometallurgical technology for simultaneous production of manganese metal, electrolytic manganese dioxide, and manganese sulfate monohydrate

The main stages of a novel hydro-electrometallurgical technology for simultaneous production of electrolytic manganese metal, electrolytic γ-MnO2, and manganese sulfate monohydrate (MnSO4∙H2O) were tested at a large laboratory scale. The unified flow sheet comprised large and small process loops. The large loop included: concentrated sulfuric acid leaching of ore obtained by high-temperature reduction of manganese oxide ore; hydrolytic and sulfide purification of MnSO4 solution; production of crystalline manganese sulfate monohydrate obtained by high-temperature autoclave treatment of purified concentrated MnSO4 solution; feeding of hot spent MnSO4 solution from the autoclave as anolyte to an AMI-7001S anion membrane-separated electrochemical reactor where γ-MnO2 was produced on titanium anodes. The small process loop included preparation and correction of the catholyte composition using MnSO4∙H2O crystallized in the autoclave, from which electrolytic manganese metal was deposited on titanium cathodes. A heat pump was used to maintain the necessary temperature difference between the anolyte and catholyte. The energy consumed by the heat pump was half that obtained using an electrical current heating device. Electrical power consumptions for the production of manganese metal, manganese dioxide, and manganese sulfate monohydrate were 9.67 Wh/g, 3.75 Wh/g, and 0.884 Wh/g, respectively.

Electrochemical Behavior of Manganese Oxide Ores Using Coke Wastewater in Sulfuric Acid Solution

The coke wastewater reductive leaching of pyrolusite ore in sulfuric acid solution was studied. This study was performed in two stages. First, the influence of tractable and refractory pollutants of coke wastewater on manganese leaching was determined. It was shown that the leaching efficiency of manganese is very sensitive to the decomposition of intractable pollutants. With the decrease of 1.85 g/L CODcr value of those contaminants, the extraction ratio of manganese increased more than 16% and exceeded 97.3%. Second, the corrosion behavior of pyrolusite ore in simulative wastewater solution was investigated using cyclic voltammograms, polarization curves, and Mott–Schottky curves. The reduction of manganese oxide ore by recalcitrant organic compounds involves two courses—the inducing conversion of manganese oxide to MnO·OH intermediate with hydrogen and free electron, which is from the oxidation of easily oxidized substances and the oxidation of persistent organic matter by this derivative. As a consequence, the latter process leads to the increment in manganese extraction efficiency. Coke wastewater is a promising reducing agent for MnO2. Likewise, it could be clarified and recycling. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13039, 2019

Experimental and reduction leaching kinetics simulation of iron-rich manganese oxide ore using tobacco stem concrete as reducing agent

Reduction leaching behaviors of Fe and Mn from an iron-rich manganese oxide ore using waste tobacco stem concrete as reducing agent were investigated in this paper with a view to determining the feasibility of tobacco stem concrete used in reduction leaching of Mn from iron-rich manganese oxide ore. Results indicated that the leaching processes of Fe and Mn were both dominated by internal diffusion, but the effects of leaching parameters on leaching ratios of Fe and Mn were different based on established leaching kinetic equations. The leaching ratio of Mn reached up to 96.18% while that of Fe kept a lower concentration (17.66%) under optimal leaching conditions, which achieved high selectivity recovery of Mn from iron-rich manganese oxide ore. In addition, the leached solution can be used as electrolytic stock solution in the production of electrolytic manganese. Characterization of the obtained electrolytic manganese product indicated that the quality of electrolytic manganese fully met the standards of YB/T 051-2003, which disclosing a novel recycling approach of utilizing the resource coming from the tobacco industry.