Catagenetic type of manganese ores:REE and isotope(δ^(13)C,δ^(18)O)geochemical features(on the example of the Usa deposit,Russia)

Chemical(REE and major elements)and isotope(δ^(13)C,δ^(18)O)composition of carbonate manganese ores and manganese-bearing carbonates of the Usa deposit(Siberia,Russia)were studied.Received data on the composition of REE exhibit both the distinct negative(Ce/Ce*_(PAAS)<1)and positive(Ce/Ce*_(PAAS)>1)cerium anomalies and the positive Eu-anomaly(Eu/Eu*_(PAAS)>1).Negative Eu-anomalies are not observed.The contents of Mn,Fe,REE,and Ce-anomalies show a positive correlation with each other.Ce-anomalies and the amount of manganese and REE in relation to the carbon isotope composition(δ^(13)C)show a negative relationship and indicate that oxidized carbon of organic matter played an important role in the concentration of manganese and REE in manganese ores.The chemical and isotope composition of examined rocks indicates on secondary formation of Mnores.Two major phases and sources are distinguished in the ore-forming process characterized by diff erent chemical(REE and ore elements)and isotope composition:(i)highgrade manganese ores(with high contents of REE and light carbon isotope composition)and(ii)low-grade manganese ores(with low contents of REE and heavy carbon isotope composition).

Reductive leaching of manganese oxide ores using waste tea as reductant in sulfuric acid solution

Manganese oxide ores from Gabon and Xiangxi were leached with waste tea as reductant in dilute sulfuric acid solution. The effects of waste tea dosage, concentration of sulfuric acid, liquid-to-solid ratio, leaching temperature and reaction time on leaching process were explored. The leaching efficiency of Gabonese manganese oxide ore reached almost 100% under the optimal condition which was determined as follows： manganese oxide ore to waste tea mass ratio of 10：1, sulfuric acid concentration of 2.5 molFL, liquid-to-solid ratio of 7.5：1, leaching temperature of 368 K, time of 8 h. The leaching efficiency of Xiangxi manganese oxide ore reached 99.8% under the optimal condition which was determined as follows： manganese oxide ore to waste tea mass ratio of 10：1, sulfuric acid concentration of 1.7 mol/L, liquid-to-solid ratio of 7.5：1, leaching temperature of 368 K, time of 8 h. The leaching process followed the internal diffusion controlled kinetic model, and the apparent activation energies of Gabonese manganese oxide ore and Xiangxi manganese oxide ore were calculated to be 38.2 kJ/mol and 20.4 kJ/mol, respectively. The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of XRD analysis and SEM analysis.

Manganese extraction by reduction-acid leaching from low-grade manganese oxide ores using CaS as reductant

The extraction of manganese from low-grade manganese oxide ores using Ca S derived from Ca SO4 as reductant was investigated. The effects of mass ratio of Ca S to ore, reduction temperature, reduction time, liquid to solid ratio（L/S ratio）, stirring speed, leaching temperature, leaching time and H2SO4 concentration on the leaching rates of Mn and Fe during the reduction–acid leaching process were discussed. The leaching rates of 96.47% for Mn and 19.24% for Fe were obtained under the optimized conditions of mass ratio of Ca S to manganese oxide ore 1：6.7, L/S ratio 5：1, stirring speed 300 r/min, reduction temperature of 95 °C for 2.0 h in the reduction process and leaching stirring speed of 200 r/min, H2SO4 concentration of 1.5 mol/L, leaching temperature of 80 °C for 5 min in the leaching process. In addition, this process can be employed in the recovery of manganese from various manganese oxide ores, and Mn leaching rate above 95% is obtained.

Preparation of manganese sulfate from low-grade manganese carbonate ores by sulfuric acid leaching

In this study, a method for preparing pure manganese sulfate from low-grade ores with a granule mean size of 0.47 mm by direct acid leaching was developed. The effects of the types of leaching agents, sulfitric acid concentration, reaction temperature, and agitation rate on the leaching efficiency of manganese were investigated. We observed that sulfuric acid used as a leaching agent provides a similar leach- ing efficiency of manganese and superior selectivity against calcium compared to hydrochloric acid. The optimal leaching conditions in sul- furic acid media were determined; under the optimal conditions, the leaching efficiencies of Mn and Ca were 92.42% and 9.61%, respec- tively. Moreover, the kinetics of manganese leaching indicated that the leaching follows the diffusion-controlled model with an apparent ac- tivation energy of 12.28 kJ·mol-l. The purification conditions of the leaching solution were also discussed. The results show that manganese dioxide is a suitable oxidant of ferrous ions and sodium dimethyldithiocarbamate is an effective precipitant of heavy metals. Finally, through chemical analysis and X-ray diffraction analysis, the obtained product was determined to contain 98% of MnSOa4·H20.

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

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-Mn2+and 1.92 g·L-1 S2 O62-,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.

Manganese leaching in high concentration flue gas desulfurization process with semi-oxidized manganese ore

Manganese leaching during high concentration flue gas desulfurization process with semi-oxidized manganese ore was studied in this paper.It was found that there were different reaction pathways among which MnO2,Mn2O3 and MnCO3 in semi-oxidized manganese ore during flue gas desulphurization and manganese leaching.High SO2 concentration facilitated redox reaction between MnO2 and SO2,and high concentration of H2SO4 accelerated MnCO3/Mn2O3 leaching from semi-oxidized ore.Kinetics study showed that manganese leaching in flue gas desulfurization process with semi-oxidized ore was controlled by a mixed-control model,that is the surface chemical reaction and mass diffusion dominated both the oxidation of SO2 and manganese leaching process.The apparent activation energy was 13.05 k J·mol-1 and the reaction orders with respect to SO2 and H2SO4 concentration were 1.38 and 0.10,respectively.Finally,a semi-empirical rate equation based on shrinking core model was derived to describe the process.

Effect of desliming on the magnetic separation of low-grade ferruginous manganese ore

In the present investigation, magnetic separation studies using an induced roll magnetic separator were conducted to beneficiate low-grade ferruginous manganese ore. The feed ore was assayed to contain 22.4% Mn and 35.9% SiO2, with a manganese-to-iron mass ratio （Mn：Fe ratio） of 1.6. This ore was characterized in detail using different techniques, including quantitative evaluation of minerals by scan- ning electron microscopy, which revealed that the ore is extremely siliceous in nature and that the associated gangue minerals are more or less evenly distributed in almost all of the size fractions in major proportion. Magnetic separation studies were conducted on both the as-received ore fines and the classified fines to enrich their manganese content and Mn：Fe ratio. The results indicated that the efficiency of separation for deslimed fines was better than that for the treated unclassified bulk sample. On the basis of these results, we proposed a proc- ess flow sheet for the beneficiation of low-grade manganese ore fines using a Floatex density separator as a pre-concentrator followed by two-stage magnetic separation. The overall recovery of manganese in the final product from the proposed flow sheet is 44.7% with an assay value of 45.8% and the Mn：Fe ratio of 3.1.

Extraction of manganese and zinc from their compound ore by reductive acid leaching

Comprehensive utilization of low grade manganese?zinc compound ore containing lead and silver with a method of reductive acid leaching was studied.According to theφ?pH diagram of Mn?Zn?H2O system,Mn and Zn can be leached simultaneously in the pH range of?2to5.61.The results showed that both hydrogen peroxide and sucrose were effective reductants which could intensify the simultaneous leaching of Mn and Zn into leachate as well as enrich Pb and Ag in the residue.95.88%of Mn and99.23%of Zn were extracted when the compound ore was leached with hydrogen peroxide in sulfuric acid media,meanwhile the contents of Pb and Ag in the residue were enriched to13.21%and489.36g/t,respectively.When sucrose was used as the reductant,the leaching efficiencies of Mn and Zn separately achieved98.26%and99.62%,and contents of Pb and Ag in the residue were as high as13.92%and517.87g/t,respectively.

Kinetics of reductive leaching of manganese oxide ore using cellulose as reductant

The kinetics of reductive leaching of manganese from a low-grade manganese oxide ore were studied using cellulose as reductant in dilute sulfuric acid medium.It was found that when the stirring speed was higher than 200 r/min,the effect of gas film diffusion on manganese extraction efficiency could be neglected,and the kinetic behavior was investigated under the condition of elimination of external diffusion influence on the leaching process.Effects of leaching temperature,mass ratio of cellulose and ore,and the sulfuric acid concentration on manganese extraction efficiency were discussed.The kinetic data were analyzed based on the shrinking core model,which indicated that the leaching process was dominated by both ash layer diffusion and chemical reaction at the initial stage,with the progress of leaching reaction,the rate-controlling step switched to the ash layer diffusion.It was also concluded that the sulfuric acid concentration had the most significant influence on the leaching rate,the reaction orders with respect to the sulfuric acid concentration were 2.102 in the first 60 min,and 3.642 in the later 90 min,while the reaction orders for mass ratio of cellulose and ore were 0.660 and 0.724,respectively.An Arrhenius relationship was used to relate the temperature to the rate of leaching,from which apparent activation energies were calculated to be 46.487 kJ/mol and 62.290 kJ/mol at the two stages,respectively.Finally,the overall leaching rate equations for the manganese dissolution reaction with cellulose in sulphuric acid solution were developed.The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of SEM and XRD analyses.

Hydrometallurgical leaching and kinetic modeling of low-grade manganese ore with banana peel in sulfuric acid

Manganese was leached from a low-grade manganese ore(LGMO)using banana peel as the reductant in a dilute sulfuric acid medium.The effects of banana peel amount,H2SO4 concentration,reaction temperature,and time on Mn leaching from the complex LGMO were studied.A leaching efficiency of~98%was achieved at a leaching time of 2 h,banana peel amount of 4 g,leaching temperature of 120°C,manganese ore amount of 5 g,and sulfuric acid concentration of 15vol%.The phase,microstructural,and chemical analyses of LGMO samples before and after the leaching process confirmed the successful leaching of manganese.Furthermore,the leaching process followed the shrinking core model and the leaching rate was controlled by a surface chemical reaction(1−(1−x)^1/3=kt)mechanism with an apparent activation energy of 40.19 kJ·mol^−1.

Reductive leaching of manganese from low-grade pyrolusite ore in sulfuric acid using pyrolysis-pretreated sawdust as a reductant

Manganese （Mn） leaching and recovery from low-grade pyrolusite ore were studied using sulfiaric acid （H2SO4） as a leachant and pyrolysis-pretreated sawdust as a reductant. The effects of the dosage of pyrolysis-pretreated sawdust to pyrolusite ore, the concentration of sulfuric acid, the liquid/solid ratio, the leaching temperature, and the leaching time on manganese and iron leaching efficiencies were inves- tigated. Analysis of manganese and iron leaching efficiencies revealed that a high manganese leaching efficiency was achieved with low iron extraction. The optimal leaching efficiency was determined to be 20wt% pyrolysis-pretreated sawdust and 3.0 mol/L H2SO4 using a liq- uid/solid ratio of 6.0 mL/g for 90min at 90℃. Other low-grade pyrolusite ores were tested, and the results showed that they responded well with manganese leaching efficiencies greater than 98%.

Contrasting REE Signatures on Manganese Ores of Iron Ore Group in North Orissa, India

The distribution pattern of Rare Earth Elements （REE） in three categories of manganese ores viz. stratiform, stratabound-replacement, and detrital of Precambrian Iron Ore Group from north Orissa, India was reported. These categories of Mn-ore differed in their major and trace chemistry and exhibited contrasting REE signature. The stratiform ores were relatively enriched in ∑REE content （697 μg·g^-1） and their normalized pattern showed both positive Ce and Eu anomalies, whereas the stratabound-replacement types were comparatively depleted in ∑REE content （211 μg·g^-1） and showed negative Ce and flat Eu signatures. The detrital categories showed mixed REE pattern. The data plotted in different discrimination diagrams revealed a mixed volcaniclastic and chemogenic source of material for stratiform categories, and LREE （Light Rare Earth Elements） and HREE （Heavy Rare Earth Elements） are contributed by such sources, respectively. In contrast, the stratabound ore bodies were developed during the remobilization of stratiform ores, and associated Mncontaining rocks under supergene condition followed by the redeposition of circulating mineralized colloidal solutions in structurally favorable zones. During this process, some of the constituents were found only in very low concentration within stratabound ores, and this is attributed to their poor leachability/mobility. The detrital ores did not exhibit any significant characteristic in respect of REE as their development was via a complex combination of processes involving weathering, fragmentation, recementation, and burial under soil cover.

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.

Hydrometallurgical Processing of Manganese Ores: A Review

Hydrometallurgy is the most suitable extractive technique for the extraction and purification of manganese as compared to all other techniques including biometallurgy and pyrometallurgical processes. In the hydrometallurgical processing of manganese from its ore, the leach liquors often contain divalent ions such as iron, manganese, copper, nickel, cobalt and zinc along with other impurities which make manganese very difficult to separate. The processes employed for solution concentration and purification in the hydrometallurgical processing of manganese include precipitation, cementation, solvent extraction and ion exchange. Solvent extraction also proves more efficient and it plays vital roles in the purification and separation of the manganese as compared to all other techniques. A detailed review of the various steps involved in the hydrometal-lurgical manganese processing, concentration and purification processes and newer processes of extraction of manganese from ores and waste materials were discussed.

Manganese extraction from high-iron-content manganese oxide ores by selective reduction roasting-acid leaching process using black charcoal as reductant

Reduction roasting-acid leaching process was utilized to process high-iron-content manganese oxide ore using black charcoal as reductant. The results indicate that, compared with the traditional reductant of anthracite, higher manganese extraction efficiency is achieved at lower roasting temperature and shorter residence time. The effects of roasting parameters on the leaching efficiency of Mn and Fe were studied, and the optimal parameters are determined as follows: roasting temperature is 650 °C, residence time is 40 min, and black charcoal dosage is 10%(mass fraction). Under these conditions, the leaching efficiency of Mn reaches 82.37% while that of Fe is controlled below 7%. XRD results show that a majority of MnO2 and Fe2O3 in the raw ore are reduced to MnO and Fe3O4, respectively.

Reductive Acid Leaching of Low Grade Manganese Ores

Manganese recoveries from low-grade ores using organic acids as reducing agents were investigated in the present work. The acid leaching potential of both oxalic acid and citric acid were estimated. Manganese leaching amount were measured by using standard manganese curve and estimated by titration method. Effects of various acid concentrations on leaching efficiency were studied. The observed result suggested prominent manganese recovery of 66% by oxalic acid at 2 M concentration whereas citric acid had less effect on leaching showing leaching percentage upto 40% in 6 days. Acid leaching of manganese ore with both the acids gave a comparative data stating that oxalic acid leached better than citric acid.

Study on hydrometallurgical process and kinetics of manganese extraction from low-grade manganese carbonate ores

In order to utilize low-grade manganese ore resources effectively, a hydrometallurgical process was developed for manganese extraction in dilute sulfuric acid medium, and the kinetics of leaching manga- nese was also investigated. At room temperature, manganese from low-grade manganese carbonate ores was extracted by sulfuric acid leaching without reductants. During the extracting process, single-factor analysis method was used to evaluate the effects of grinding fineness, sulfuric acid concentration, liquid-to-solid ratio, agitation rate and leaching time on the leaching efficiencies of Mn and Fe. The optimal leaching conditions are determined as coarse particles of below 2 mm size （without ball-milling）, sulfuric acid concentration of 0.86 mol/L, liquid-to-solid ratio of 5：1, agitation rate of 150 r/rain and leaching for 180 min at room temperature. Under the optimal conditions, the leaching efficiencies of Mn and Fe are 96.21g and 13.35%, respectively. In addition, through the experiments at different temper- atures, it is found that the leaching process follows the shrinking core model under the conditions of changing acid concentration and intermittent reaction device. Moreover, the apparent activations of effective diffusion and chemical reaction in the kinetic model are calculated to be 18.83 and 27.15 kJ/mol, respectively.

A Comprehensive Utilization Process for Black Manganese-silver Ores by Pyrite Reducing Method

On a 5 kg bench scale, the separating of Mn-Ag from black manganese-silver ores by pyrite reducing method was investigated. Leached Mn content of 98.3% (mass fraction) along with silver loss of 1.5% is achieved. The purification of solution by the precipitation method was effectively used. Chemical grade gamma -MnO2 with TMn content of 60.13% (mass fraction) and MnO2 content of 92.28% (mass fraction) is obtained. Mn recovery efficiency is 94.04%. The residues from leaching Mn process of black Mn-Ag ores was employed for silver extraction by cyanidation with leached silver content of 92.17% (mass fraction), displacement ratio of 99.5%, recovery efficiency of 90.79%. Therefore, the present study provides a feasible process for making full use of black manganese-silver ore resources.

Reductive leaching of low-grade manganese ore with pre-processed cornstalk

Cornstalk is usually directly used as a reductant in reduetive leaching manganese. However, low utilization of cornstalk makes low manganese dissolution ratio, In the research, pretreatment for cornstalk was proposed to improve manganese dissolution ratio. Cornstalk was preprocessed by a heated sulfuric acid solution （1.2 M of sulfuric acid concentration） for 10 min at 80℃. Thereafter, both the pretreated solution and the residue were used as a reductant for manganese leaching. This method not only exhibited superior activity for hydrolyzing cornstalk but also enhanced manganese dissolution. These effects were attributed to an increase in the amount of reductive sugars resulting from lignin hydrolysis. Through acid pretreatment for cornstalk, the manganese dissolution ratio was improved from 50.14% to 83.46%. The present work demonstrates for the first time the effective acid pretreatment of cornstalk to provide a cost-effective reductant for manganese leaching.

Rare earth elements(REE)and isotope composition(δ^(13)C andδ^(18)O)of manganese ores of Chiatura deposit(Georgia):features of ore formation and genesis

The rare earth elements(REE)geochemistry and the isotope(δ^(13)C,δ^(18)O)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 isotopic ally light CO_(2)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.