Mn Grade Research Articles

Innovative utilization of 2-(4-Butoxyphenyl)acetohydroxamic acid as collector for the selective separation of rhodochrosite from calcite and dolomite

A novel collector 2-(4-Butoxyphenyl)acetohydroxamic acid (BAHA) was actively considered in the flotation of rhodochrosite. Flotation behaviors and BAHA adsorption concerning rhodochrosite, calcite and dolomite were systematacially investigated through microflotation tests, adsorption experiments, zeta potential measurements, FTIR and XPS analyses. Microflotation results showed that rhodochrosite performed a better floatability than calcite and dolomite at pH 8.0–10.0. Also, the adsorption amounts of BAHA collector on the rhodochrosite surface were obviously greater than those of calcite and dolomite. The results of zeta potential, FTIR and XPS analyses indicated that BAHA adsorbed onto rhodochrosite surfaces through chemisorption, electrostatic attraction and intermolecular hydrogen bonding, chemisorption and electrostatic attraction for calcite, and only chemisorption for dolomite. The interaction mechanisms between BAHA collector and mineral surfaces were responsible for the differences in the BAHA adsorption and floatability between rhodochrosite and two gangues. The flotation separation tests of three minerals confirmed that the rhodochrosite concentrate with Mn grade of 24.64% and recovery of 87.94% could be obtained. BAHA is a high selective collector and can realize the flotation separation of rhodochrosite against dolomite and calcite.

Impact of dredging on the environmental state of a small river with considering the composition of bottom sediments

Reports on the environmental impact assessment of planned activities aimed at restoring the hydrological regime and sanitation of rivers do not always pay attention to in-depth analysis of the physicochemical composition of bottom sediments. The silt deposits have proven to be a good ameliorant for agricultural lands, provided they are of satisfactory quality. Bottom sediments, especially their fine alluvial fraction, accumulate various compounds and trace elements, including heavy metals. Analysis of the content of iron Fe, manganese Mn, cobalt Co, chromium Cr and determination of the integrated level of contamination of bottom sediments did not reveal their toxic contamination in the area of the village Kleshnivka and the village Petrykivka. Determination of "geoaccumulation indices" by G.M. Mueller allowed to classify the sediments of the Chaplinka River as unpolluted, and the man-caused load on the hydroecosystem as low. In compliance with the recommendations on the content of Mn grades in the soil cover of the obtained fifth Igeoclass, which provides heavy pollution and significant man-caused load on the hydroecosystem. To characterize the processes occurring in the hydroecosystem of the Chaplynka River, the bottom accumulation coefficient was calculated. The assessment of the ecological status of hydroecosystems revealed an overwhelming ecological emergency. There is a significant threat of deposits of iron Fe, manganese Mn in bottom sediments. Despite the low risk of contamination of bottom sediments with chromium Cr, the risk will increase due to the rather variable chemical composition of surface waters, and hence the possibility of an ecological crisis for the hydroecosystem. The sanitary condition of a small river could be improved by restoring its hydrological regime. The decrease in the efficiency of dredging works is related to the regulation of the regulation of the riverbed. In the vast majority of cases, hydraulic structures are not provided for or do not correspond to the current level regime of watercourses. After clearing the river bed, there is a danger of their secondary silting, due to the abandonment of part of the temporary dumps on the banks within the water protection zones without fixing.

Analisis Karakteristik Mineralogi dan Geokimia Berdasarkan Zona Profil Endapan Nikel Laterit (Studi Kasus: Blok X PT Ang and Fang Brother, Site Lalampu, Kecamatan Bahodopi, Kabupaten Morowali, Provinsi Sulawesi Tengah

Regionally, the study area is located in the Ophiolite Belt of East Sulawesi, particularly in the Tomata Formation (Tmpt), and is composed of igneous rock distribution in the Ultramafic Complex (Ku). The exposed of ultramafic rocks, caused the study area to contain elements of economic value such as nickel. The study aims to identify the constituent minerals, determine the abundance of elements and compounds, as well the correlation of major and minor elements and compounds based on the profile zone of laterite nickel deposits. Study data were in the form of soil and rock samples, and drilling data as many as 59 points. The mineral content of the study results was obtained based on the analysis of X-ray Diffraction and Petrography, while the univariate and bivariate statistical analysis was carried out on the drilling data. The results of the analysis obtained assemblages of minerals in the form of goethite, hematite, chlorite, and quartz in the limonite zone; antigorite, enstatite, chlorite, quartz, and magnetite in the saprolite zone; and lizardite, enstatite, spinel, and magnetite in the bedrock zone, with the bedrock type being serpentinized harzburgite. The results of the descriptive analysis showed the grade of major elements and compounds, which are Fe, SiO2, MgO, and Al, as well as minor elements, which are Ni, Cr, Co, Ca, and Mn which varied in each zone, where grade of SiO2, MgO, and Ca increased to the bottom of the profile, and the grade of Fe, Al, Cr, Mn, and Co decreased towards the bottom of the profile, while Ni increased to the saprolite zone. The results of the correlation of elements and compounds in the limonite zone are Cr vs Mn; SiO2 vs MgO and Ca; Ni vs Co and Cr; Fe vs Co positive is very strong to strong correlation, while Fe vs SiO2, MgO vs Al; Al vs Ni is strong negative correlation. Saprolite zone Fe vs Al, Cr, and Co; Cr vs Mn and Co; Mn vs Co; SiO2 vs MgO; Fe vs Mn; Al vs Cr, Mn, and Co were very strong to strong positive correlation, while Fe vs SiO2 and MgO; SiO2 vs Co; MgO vs Cr and Co; SiO2 vs Al, Cr, and Mn; MgO vs Al and Mn were very strong to strong negative correlation. Bedrock zones of Fe vs Cr, Mn, and Co; Cr vs Mn; Fe vs Al; Co vs Al, Cr, and Mn were very strong to strong positive correlation, while MgO vs Fe and Cr were strongly negative correlation.

Effects of strain rate on austenite stability and mechanical properties in a 5Mn steel

The austenite stability and the mechanical properties in a typical medium Mn grade steel, i.e., 5Mn steel, were investigated under a wide range of strain rates through the combination of experimental and theoretical methodologies. The obtained results indicate that austenite is more stable at a high strain rate, which is due to the suppression of the austenite to martensite transformation. This suppression is attributed to the increased stacking fault energy and the high deformation energy barrier. Moreover, the suppression of martensitic transformation also leads to the decrease in the ultimate tensile strength and the uniform elongation. Owing to the increase in an adiabatic heating temperature, an increase in the uniform elongation is acquired at a high strain rate. The obtained fundamental study results shed light on a wide application of the medium Mn steel under different strain rate conditions.

Influence of Mineralogy on the Dry Magnetic Separation of Ferruginous Manganese Ore—A Comparative Study

Magnetic separation is often considered pertinent for manganese ore beneficiation when the ore is abundant with siliceous rich gangue mineral phases. However, the process is deemed to be inapposite for the ferruginous type of ore, and remains a grey area of research. In the present investigation, two different types of manganese ore were studied in detail to understand the influence of mineralogy on their magnetic separation performance. Detailed experiments were performed by varying the critical variables of the dry magnetic separator, and the separation features were studied. The ore samples were thoroughly characterized by various techniques, including an automated advanced mineralogical tool. The mineralogical results revealed that primary manganese bearing minerals in both the ores are rich in cryptomelene, pyrolusite, psilomelane, and bixybyite. Similarly, the major gangue minerals were alumina-bearing minerals and iron-bearing phases (hematite and goethite). The optimum grade that could be obtained from single-stage dry magnetic separation was 35.52% Mn, and with a Mn:Fe ratio of 1.77, and 44% Mn recovery in the case of sample 1; whereas, a 33.75% Mn grade, with a Mn:Fe ratio of 1.66 at Mn recovery of 44% was reported for Sample 2. It was observed that both samples had a similar input chemistry (~28% Mn, ~1 Mn: Fe ratio) however, they had distinctive mineralogical assemblages. Furthermore, it was observed that the liberation of manganese mineral was in a course size range, i.e., 300 to 450 µm, while the association of iron and manganese bearing phases was lower in sample 1 when compared to sample 2.

Multistage genesis of the late Cretaceous manganese karst-hosted Tasdremt deposit (High Atlas, Morocco)

The eastern part of the Souss Basin (Morocco) contains several Mn deposits in the Tasdremt district. Three Mn orebodies occur within the Cenomanian-Turonian dolostones and the Senonian (Coniacian to Maastrichtian) detrital series, the main orebody being located at the boundary between them. The Mn ores consist of coronadite group minerals, mostly coronadite and hollandite, in a karstified dolostone. New field observations, petrographic analyses, and geochemical data define the Tasdremt deposits as a karst-hosted accumulation (11–60 wt.% Mn), particularly enriched in Ba (1.5–8.2 wt.%) and Pb (1.0–5.0 wt.%) with poor contaminations in Al, Fe, and P. This study shows that the ore-forming process is similar to that occurring in the Imini C3 level, located ~ 100 km to the north-east. Such similarities with the high-grade pyrolusite-bearing ore suggest that the Tasdremt deposit is a lateral equivalent of the Imini deposits. However, the scarcity of pyrolusite in Tasdremt results in lower Mn grades, the Tasdremt ores being considered an aborted/incomplete system in comparison with the Imini deposits. 40Ar/39Ar geochronology of K-bearing Mn oxides yields late Cretaceous ages, defining three phases at ~ 91.5 Ma, ~ 77.5–82 Ma, and ~ 65–67 Ma. Although the source of metals remains hypothetical, mineralizing fluids were carried by O2-free groundwater that mixed with O2-rich shallow meteoric waters at the Tasdremt depositional site. The dissolution of the host dolostones and the karst environment have provided suitable conditions for the precipitation of Mn oxides, causing the coeval increase of pH and Eh, respectively. The Early Atlasic deformation during the Late Cretaceous is associated with mineralization events and was responsible for creation of low stand reliefs from Tasdremt to Imini. This period enabled karstification and mineralization. Connecting the Tasdremt deposits to other African Mn deposits is difficult since the latter consist of laterite resting above Paleoproterozoic Mn protores, and consequently formed under different conditions from karst-hosted deposits. It is likely that other Mn occurrences formed along the Atlas belt in similar settings.

Hybrid multivariate typological model for the banded iron formations from the Bonito mine, Northeastern Brazil

Typological ore delineation is a basic procedure that provides various bases in ore geology on which crucial developments rely on, in particular, those supporting mineral resource evaluation. To deal with several complex issues related to typological delineation of heterogeneous ore bodies, an unusual hybrid multivariate approach, based on a skillful combination of geochemical/geological knowledge and correspondence analysis (CA), was established. This approach was tested on banded iron formations (BIF) in the Bonito mine, Northeastern Brazil, enhancing the available geochemical knowledge by revealing grade combinations related to geological processes causing such deposits. Petrographic studies helped identify four main BIF-types: amphibolitic, hematitic, martitic, and magnetitic itabirites. An exhaustive geochemical database comprising 1,384 BIF samples assayed for Fe2O3, SiO2, Al2O3, P, and Mn grades was established and classified for the aforementioned BIF-types. The methodology provides an updated typological model based on a unique aspect of CA that allows a simultaneous projection of samples and their characteristics onto axes of the same abstract space; this helps validate mathematical results with geological information linked to sample attributes. The BIF typology model was established by applying K-means clustering to factorial scores derived through CA. Hence, the BIF typological model was updated, and new geochemical BIF-types helped interpret some of the main geological processes related to them. Geochemically, the factorial axes could be related to: 1) Iron rich BIF rocks, which are clearly represented on the positive side of Axis 1, comprising almost 50% of the total variance; 2) Manganese and alumina, associated with high silica content, by attachment to Axis 2, which describes a possible and critical terrigenous input.

Optimisation of Operational Parameters of a Spiral Classifier Using Design of Experiment (DOE)

Abstract
 Classifying Mn Ore to improve upon the grade and the properties has become a crucial activity for the Mn industry since it increases the market value of the ore. Ghana Manganese Company (GMC) has renovated their oxide washing plant by integrating it with a spiral classifier to make a batch system operating process. Particle size of <3.35mm (Mn grade of 43-47%) obtained from the primary section of the plant served as feed to the classifier and with the plant condition (i.e. at 60 min washing time, 30 rev/min speed of spirals and feed tonnage of 6 t), Mn grade of 49% was achieved. This paper focused on the optimisation of some selected operational parameters of the classifier to obtain a Mn grade >50% using Design of Experiment (DOE). Series of test works were designed using the DOE for the classifier using the constraints of washing time (30-90 min), speed of spirals (20-40 rev/min) and feed tonnage (6-9 t). The outcome of the test work after simulation showed that all the selected parameters had a great influence on Mn grade. The spiral speed and feed tonnage correlated negatively to the Mn grade with washing time correlating positively. Operating the spiral classifier at a feed rate, spiral speed and washing time of 6 t, 25 rev/min, and 30 min, respectively, yielded Mn grade of 53%. A Confirmatory test using the established conditions gave a Mn grade of 53%, which is a 4% increment in the previous Mn grade which was 47%. The outcome of the studies is the new established operational conditions which is adhered to by the plant, producing a manganese concentrate grade ranging between 52-54%.
 
 Keywords: Design of Experiment (DOE), Spiral Classifier, Grade, Manganese

Extraction of Mn from Black Copper Using Iron Oxides from Tailings and Fe2+ as Reducing Agents in Acid Medium

Exotic type deposits include several species of minerals, such as atacamite, chrysocolla, copper pitch, and copper wad. Among these, copper pitch and copper wad have considerable concentrations of manganese. However, their non-crystalline and amorphous structure makes it challenging to recover the elements of interest (like Cu or Mn) by conventional hydrometallurgical methods. For this reason, black copper ores are generally not incorporated into the extraction circuits or left unprocessed, whether in stock, leach pads, or waste. Therefore, to dilute MnO2, the use of reducing agents is essential. In the present research, agitated leaching was performed to dissolve Mn of black copper in an acidic medium, comparing the use of ferrous ions and tailings as reducing agents. Two samples of black copper were studied, of high and low grade of Mn, respectively, the latter with a high content of clays. The effect on the reducing agent/black copper ratio and the concentration of sulfuric acid in the system were evaluated. Better results in removing Mn were achieved using the highest-grade black copper sample when working with ferrous ions at a ratio of Fe2+/black copper of 2/1 and 1 mol/L of sulfuric acid. Besides, the low-grade sample induced a significant consumption of H2SO4 due to the high presence of gangue and clays.

Systematic study on separation of Mn and Fe from ferruginous manganese ores by carbothermic reduction roasting process: Phase transformation and morphologies

Carbothermic roasting reduction followed by magnetic separation process is reported as an effective technological process to separation and recovery of Fe and Mn from low-grade ferruginous manganese ores (Fe–Mn ores) as an acceptable feed to meet the demands of the developing manganese industry. In this study, the effects of operating variables on the recovery and grade of Fe and Mn are initially investigated during the carbothermic roasting reduction process followed by magnetic separation. Then, the phase transformation and morphologies of spinel (FeyMn1−y)Al2O4, fayalite FeyMn2−ySiO4 and (FeO)x(MnO)1−x are investigated by SEM-EDS, XRD, TG/DTG and thermodynamic analyses. Finally, the stepwise reduction and interfacial reaction of three types of phases are investigated at 700–1100 °C for 10–120 min to clarify the reason for the poor separation of Mn and Fe from Fe–Mn ores. The effect of MnO on the stepwise reduction behavior of Fe2SiO4 and FeAl2O4 is analyzed in detail. Finally, the tight integration of the MnO phase with a metallic Fe–Mn alloy derived from the stepwise reduction of (FeO)x(MnO)1−x are closely associated with the stepwise reduction of the FeyMn2−ySiO4, (FeyMn1−y)Al2O4 and (Fe,Mn)2O3 phases. In addition, the formation mechanism and the interfacial reduction reaction of (FeO)x(MnO)1−x, (FeyMn1−y)Al2O4 and FeyMn2−ySiO4 are systematically analyzed to show the effect of the MnO phase on the stepwise reduction of the Fe2SiO4 and FeAl2O4 phases. Finally, some suggestions were recommended for the carbothermic reduction followed by magnetic separation for utilizing the Fe–Mn ores effectively. The manganese-rich product an acceptable feed containing 53.60 wt.% total Mn with the Mn recovery of 89.38% and mass fraction of Mn/Fe of 5.43 are obtained.

In Situ Quantitative Assessment of the Role of Silicon During the Quenching and Partitioning of a 0.2C Steel

Silicon is an essential alloying element added in quenching and partitioning (Q&P) steels to delay and/or suppress carbide precipitation. However, there is a strong industrial interest to reduce the silicon content as it has detrimental effects on the metallurgical route. This work investigates by means of in situ high-energy XRD (HEXRD) the effect of silicon on the microstructural evolution during quenching and partitioning of a commercial 0.2C-2.3Mn grade. The results of this study highlight the role of the bainite transformation during the reheating and partitioning steps for effective austenite retention. Silicon influences the kinetics of austenite decomposition into bainite and finally promotes the stabilization of austenite. This is explained by the ability of silicon to suppress carbide precipitation (i) at the interface between bainite and austenite and (ii) in the martensite matrix. Carbide precipitation at the bainite/austenite interface decreases the amount of carbon that diffuses from bainite to austenite, subsequently accelerating the bainite transformation kinetics and preventing austenite stabilization. Carbide precipitation in martensite reduces the amount of carbon available for partitioning in austenite, further preventing its stabilization. Additions of elements such as Cr or Mo could be therefore considered in order to reduce the austenite decomposition in low-silicon steel grades.

Micro and Nanoscale Characterization of Complex Multilayer-Structured White Etching Layer in Rails

Micro- to nano-scale characterization of the microstructures in the white etching layer (WEL), observed in a Dutch R260 Mn grade rail steel, was performed via various techniques. Retained austenite in the WEL was identified via electron backscatter diffraction (EBSD), automatic crystallographic orientation mapping in transmission electron microscopy (ACOM-TEM), and X-ray diffraction (XRD). EBSD and ACOM-TEM methods were used to quantify grains (size range: 50 nm–4 μm) in the WEL. Transmission electron microscopy (TEM) was used to identify complex heterogeneous microstructural morphologies in the WEL: Nano-twinning substructure with high dislocation density in the WEL close to the rail surface and untransformed cementite and dislocations in the WEL close to the pearlite matrix. Furthermore, atom probe tomography (APT) revealed a heterogeneous through-thickness distribution of alloying elements in the WEL. Accordingly, the WEL is considered a multi-layered martensitic microstructure. These findings are supported by the temperature calculations from the shape analysis of the manganese profile from APT measurements, related to manganese diffusion. The deformation characteristics of the WEL and the pearlite beneath the WEL are discussed based on the EBSD measurements. The role of deformation in the martensitic phase transformation for WEL formation is discussed.

Beneficiation and agglomeration of manganese ore fines (an area so important and yet so ignored)

Unpredictable changes in demand and prices varying from very attractive to depressing levels have thrown all Manganese ore mines out of normal operating gear. The supply has to be in time-bound fashion, of dependable quality and continuous. With setting-up of numerous small units and with existing ferro-alloy units, ore supply has become extremely sensitive issue. Due to unpredictable swing in price of Mn ore lumps, furnace operators found it economic and convenient to use fines, even at great risks to furnace equipment and operating persons and therefore risks & damages were conveniently & comfortably ignored. Beneficiation Cost(Operating) approx. – (ferruginous ore) – Roast reduction followed by magnetic separation route-particulars – Water 20/-, Power 490/-, Coal fines-675/-, OH-250/-totaling to Rs.1435/T. (Figures are based on actual data from investigations on Orissa & Karnataka sector ores). Feed Grade Mn- 28 to 32 %, Fe – 14 to 25 %, Concentrate (Beneficiated ore fines)- - Mn- 45 to 48 %, Fe – 6 to 8 %., Recovery - 35 %, Price of 28-30 % Mn ore fines = Rs. 2400/T, Cost of Concentrated fines (45/48% Mn grade) = Rs. 8300/T, Price of 47-48 % Mn Lumpy ore = Rs.11,000/T. Sintering Cost (Operating) – Approx-Rs.1195=00/T Sinter. Therefore cost of Sinter produced from beneficiated concentrate is 9130+1195 = Rs. 10325. The difference in cost of 48%Mn ore Lumps & 48%Mn sintered concentrate = 11000-10325 = Rs.675/T. The main purpose of this paper is to show that establishment of beneficiation unit & Sintering unit is economically feasible. There are many misconcepts, still prevailing, about use of Mn ore sinters. Few of the main misconcepts are- 1)Sinters bring no benefit – technical or economical.2) Sinters are very friable and disintegrate easily into high fines during handling/transportation. 3) Fines below 100 mesh cannot be sintered. 4) Silica increases to high level during sintering, resulting in to high slag volume thereby higher power consumption. All are false. Sinters have already been proved to bring enormous technical benefits in smelting operation. However small mine owners find it practically impossible to set up a small beneficiation and/or sintering unit at mine site. Recent advances in dry or pneumatic separation which depends on density difference between valuable mineral and gangue/waste rock, are proving to be advantageous & effective because of its small capacity. Capacity is 5 T/hr or 10 T/hr. When applied to low grade high silica Iron ores Iron content has been found to be enhanced by 8 to 10 % from 48% to 58 %, with overall wt. recovery of 60 to 70 %. Recently this technique was applied to low grade siliceous Mn ore with very encouraging results. Mn content has been found to be enhanced from 25 +/- 2 % to 37 +/- 2 % and with 50 to 65% wt. recovery. Size of feed is restricted to (i) 6 to 25 mm and (ii) 2 to 6 mm. Due to Modular design it is possible to put up units from 50 TPD to 800 TPD capacity.

Combination Methods of Hematite-Braunite Ore Processing

The material composition and process properties of hematite–braunite iron–manganese ore from Yuzhny Khingan deposit of Russian Far East are studied. The source of manganese in the ore is mostly braunite. The mineralogy and petrography of the ore and products of its processing are characterized. Noble metal minerals are found in the ore; the gold contains platinum and silver admixtures. Producibility of manganese concentrates of 37.85–46.46% Mn grade using the circuit of multi-stage magnetic separation in weak and strong magnetic fields and gravity concentration is experimentally proved.

Novel and green metallurgical technique of comprehensive utilization of refractory limonite ores

Limonite ores are a common and widely distributed refractory iron oxide ores in the world. In this paper, in view of the growing development of steel and iron industry, the depletion of easy-processing iron ores and growing environmental concerns, a novel and green technique route was proposed to comprehensive utilize limonite ores by asynchronously recovering various valuable elements. The technique route included three stages: recovery (enrichment) of Fe and Mn by removal of impurities (Al and Si phases) via microwave-assisted roasting-acid leaching process using alkali lignin and Na2CO3-Na2SO4 binary sodium salts as roasting additives, where Na2SO4 was favorable for the aggregation and growth of iron-rich grains, Na2CO3 could enhance the activation of Al and Si phases and then improve the acid leaching of Al and Si, and alkali lignin has a favorable effect on the leaching; recovery of Si by ripening the acid leached liquor, where Si was enriched and extracted in the form of silica gel through the polymerization of silicic acid; and stepwise recovery of small amount of leached Fe and Mn as well as Al by neutralizing and precipitating of filtrate from the 2nd stage using NaOH solution and NaHCO3 solution as precipitating reagents, respectively. The final Na2SO4 and Na2CO3 filter liquor could be recycling used in the roasting process by evaporation pretreatment, achieving zero pollution and zero waste. By performing acid leaching process on the roasted ore treated at 200 °C, 600 W for 30 min in the presence of 5% alkali lignin, 5% Na2CO3 and 5% Na2SO4, an iron concentrate assaying 57.08% Fe with the corresponding iron recovery ratio of 92.04% and yield of 64.66% was obtained from the refractory limonite ore containing 40.10% Fe, 8.69% Mn, 9.40% Al, and 6.92% Si. Besides, Mn was simultaneous enriched in the iron concentrate with a Mn recovery ratio of 71.73% and a Mn grade of 9.64%. Simultaneously, 84.11% of Si and 80.26% of Al existed in the limonite ore were extracted, and leaching ratios of Fe and Mn were only 7.96% and 28.27%, respectively. Subsequently, silica gel containing 93.31% SiO2 and Al(OH)3 precipitate containing 41.59% Al2O3 and Mn-Fe precipitate with 33.08% Fe and 14.83% Mn were successfully stepwise obtained by the last two stages. The proposed technique with the advantages of mild reaction conditions and discharge reducing, meeting the demands of green metallurgy, would potentially be a feasible route for the utilization of limonite ores, easing the shortages of iron and promoting the sustainable development of steel and iron industry.

Carbothermic Reduction of Ferruginous Manganese Ore for Mn/Fe Beneficiation: Morphology Evolution and Separation Characteristic

In the present paper, beneficiation of Fe and Mn elements from a ferruginous manganese ore via carbothermic reduction followed by magnetic separation process was investigated in detail. The effects of the experimental parameters were systematically discussed. Iron-rich products with an Fe grade of 62.3% and 88.2% of Fe recovery, and manganese-rich product with a Mn grade of 63.7% of and 70.4% of Mn recovery were obtained, respectively, at an optimal temperature of 1100 °C, with a roasting time of 100 min, anthracite addition of 25%, milling fineness of 90% passing 0.074 mm, and a magnetic intensity of 140 A/m. Furthermore, the morphology evolution and phase transformation laws along with reduction process were revealed by optical microscope, scanning electron microscope equipped with energy dispersive X-ray detector (SEM-EDX), X-ray diffraction (XRD), and chemical phase analysis. The results demonstrated that the ferruginous manganese ore reduction can be described as follows: plate-like Fe-Mn symbiotic phase decomposition → granular MnO phase formation → fine metallic iron formation → aggregation of metallic iron → boundary development between Fe and Mn phases.

Magnetic Separation and Magnetic Properties of Low-Grade Manganese Carbonate Ore

The relation between the magnetic separation behavior and magnetic properties of a low-grade manganese ore was analyzed before and after treatment by direct reduction with coal. It was found that raw ore with an initial average grade of 10.39% Mn and consisting of diamagnetic and paramagnetic minerals can be concentrated by high-intensity magnetic separation to produce a salable product with a grade of 22.75% Mn and a recovery of 89.88%. In contrast, direct reduction of the ore results in a new Mn-Fe oxide phase formed with a combination of ferromagnetic and paramagnetic properties, thereby increasing the magnetic susceptibilities of the ore by almost two orders of magnitude. The grade of Mn for the roasted ore could only be concentrated to 15.49% with a recovery of 66.67%. Therefore, it is concluded that the low-grade manganese ores with antiferromagnetic and paramagnetic (or diamagnetic, but not strongly ferromagnetic) properties could be efficiently beneficiated via high-intensity magnetic separation.

Strengthening pelletization of manganese ore fines containing high combined water by high pressure roll grinding and optimized temperature elevation system

Pelletization is one of useful processes for the agglomeration of iron ore or concentrates. However, manganese ore fines are mainly agglomerated by sintering due to its high combined water which adversely affects the roasting performance of pellets. In this work, high pressure roll grinding (HPRG) process and optimization of temperature elevation system were investigated to improve the strength of fired manganese ore pellets. It is shown that the manganese ore possesses good ballability after being pretreated by HPRG twice, and good green balls were produced under the conditions of blending 2.0% bentonite in the feed, balling for 7 min at 16.00% moisture. High quality roasted pellets with the compressive strength of 2711 N per pellet were manufactured through preheating at 1050 °C for 10 min and firing at 1335 °C for 15 min by controlling the cracks formation. The fired manganese pellets keep the strength by the solid interconnection of recrystallized pyrolusite grains and the binding of manganite liquid phase which filled the pores and clearance among minerals. The product pellets contain high Mn grade and low impurities, and can be used to smelt ferromanganese, which provides a possible way to use imported manganese ore fines containing high combined water to produce high value ferromanganese.

Calcination and characterisation studies of a Brazilian manganese ore tailing

This paper discusses the systematic analysis of the results of calcination as a function of size fraction performed on a sample of Brazilian silicate–carbonate manganese ore tailing at 800°C. The raw materials and the corresponding calcination products were analysed using several analytical techniques, including determination of density, specific surface area and porosity, chemical analysis and X-ray diffraction. The morphology and chemical composition of the calcination products were analysed by using scanning electronic microscopy equipped with energy-dispersive X-ray spectrometer (SEM/EDS). Results indicate that the manganese ore tailing consists of silicates, namely, spessartine (Mn3Al2(SiO4)3), tephroite (Mn2(SiO4)) and rhodonite ((Mn,Fe,Mg,Ca)5(SiO3)5) and rhodochrosite (MnCO3). The loss of CO2 and OH during the thermal decomposition of the carbonate (rhodochrosite and dolomite) and hydrated minerals (kaolinite, muscovite and antigorite) in air atmosphere at 800°C resulted in: (1) decrease of the specific surface area and porosity, (2) increase in the density and Mn grade from 27.6% to 32.2% and (3) increase in SiO2 grade from 26.7% to 30.1%. These results indicate that this material is within the chemical specifications of Fe–Si–Mn alloy.

QUANTITATIVE ASSESSMENT OF POLYMETALLIC NODULES RESOURCE OF CC ZONE BASED ON FUZZY ARTMAP

The eastern CC zone,known with detailed survey and availability of abundant data,was selected as the study area in this paper.The Fuzzy ARTMAP algorithm was adopted for model training at surveyed stations,and the relation models were established between grade of metal Mn,Co,Ni,Cu and regional ore-controlled elements,such as mean oceanic crust age,sediment thickness,hypsography and sediment types.Upon the basis,a Fuzzy ARTMAP quantitative assessment model was obtained.Applying the model,the resources in both surveyed and unsurveyed regions was estimated.Comparing the surveyed data with the calculated data for surveyed stations,the relative error of Mn,Cu,Co,Ni was 4.5%,9.1%,20.8% and 7.4%.Taking 30% as the error allowed,the accuracy of the results was 100%,96.7%,72.5% and 98.9% respectively.The error test suggests that the model is feasible for polymetallic nodules resource assessment as the reliability required,and can be used for study of the spatial distribution of polymetallic nodules.