• Resources Recycling
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• v.12 no.1
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• pp.33-40
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• 2003

Mn was extracted by using a nitric acid from the reduced ferromanganese dust and the basic experiments were taken to refine the manganese nitrate solution by means of precipitation of Ca, Mg oxalate. The dust was generated in AOD process producing a medium-low carbon ferromanganese and collected in the bag filter. Manganese oxide content in the dust was about 90% and its phase was confirmed as $Mn_3$$O_4$. $Mn_3$$O_4$ in the dust was reduced to MnO by roasting with activated charcoal. The main impurities in the extracted solution prepared by leaching the reduced dust with nitric acid were Na, K, Fe, Si, Ca, Mg etc. Among them, Fe was removed by controlling pH of the solution more than 4 and precipitating $Fe(OH)_3$, simultaneously silicious material solved in the solution was removed by co-precipitation with the ferric hydroxide. Addition of 150 g reduced dust into 4N HNO3 solution 1$\ell$ was appropriate to control the pH of the solution to pH 4. To differ greatly the solubilities of manganese oxalate and calcium or magnesium oxalate in a solution containing a high concentration of Mn, pH of 4 or less and addition of ($NH_4$)$_2$$C_2$$O_4$ in equivalent with Ca and Mg are recommended. At this time, the higher temperature was the shorter the precipitation reaction time was needed.

• Journal of Life Science
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• v.15 no.1 s.68
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• pp.94-99
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• 2005

Sixty four bacterial colonies which were able to oxidize the manganese were isolated from soil samples in Mokcheon and Ochang area. Among them, one bacterial strain was selected for this study based on its higher manganese oxidation, and this selected bacterial strain was identified as Aeromonas sp. MN44 through physiological-biochemical test and analysis of its 16s rRNA sequence. Aeromonas sp. MN44 was able to utilize lactose but did not utilize various carbohydrates as a sole carbon source. Aeromonas sp. MN44 showed a very sensitive to antibiotics such as kanamycin, chloramphenicol, ampicillin, tetracycline and spectinomycin, and heavy metal such as cadmium. But this strain showed a high resistance up to mg/ml unit to heavy metals such as lithium and manganese. Optimal manganese oxidation condition of Aeromonas sp. MN44 was pH 7.4 and manganese oxidation activity was inhibited by proteinase K and boiling treatment. So, we concluded that this factor was protein. The manganese oxidizing factor produced by Aeromonas sp. MN44 was partial purified by ammonium sulfate precipitation, DEAE-Toyopearl 650M ion exchange chromatography and Sephadex gel filtration chromatography. Its molecular mass was about 113 kDa.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.403-404
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• 2006

Sintered materials have been applied widely in Valve Seat Inserts (VSI). The demands for VSIs are not only good heat and wear resistance but also good machinability. The sintered materials, which are made of a mixture of manganese containing iron powder and certain types of sulfide powder, have superior machinability due to precipitation of the fine MnS particles in the matrix. This report introduces a new VSI material, which has both superior machinability, and wear resistance due to applies of this "MnS precipitation" technique.

• Journal of Korea Foundry Society
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• v.3 no.3
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• pp.174-180
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• 1983

The matrix changes and graphite formation in high manganese cast iron (Fe-12Mn-3.5C) are studied with increasing nickel and silicon content. Also, the decomposition of carbides and graphite precipitation are studied by adequate heat treatment.The results obtained in this work are as follows. 1. In high manganese cast iron, fine flakes graphite appeared by adding 5 wt% nickel and A-type flakes graphite can be obtained by adding 7 wt% nickel. 2. Nodular graphite are obtained by graphite spheroidizing treatment with same melt. 3. In high manganese cast iron containing 7 wt% nickel, full austenitic matrix with nodular graphite can be achieved by water quenching after 10 hours' solution heat treatment at $1050^{\circ}C$ in case of containing 2.0 wt% silicon, and 6 hours' at the same temperature in case of containing 2.5 wt% silicon.

• Economic and Environmental Geology
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• v.15 no.4
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• pp.205-219
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• 1982

The Eosangcheon manganese ore deposits occur as supergene weathering deposits along quartz porphyry dikes developed in the Ordovician Heungweolri dolomite and Samtaesan limestone formations. The manganese ores are composed of manganese oxide minerals and associated other minerals. Rancieite and todorokite are abundantly found, and birnessite, nsutite, pyrolusite and chalcophanite are found in minor quantities. Associated other minerals are calcite, gypsum, goethite, lepidocrosite, quartz, and sericite. Microscopic, chemical, X-ray powder diffraction, infrared absorption spectroscopic and differential thermal analyses have been made for manganese oxide minerals and associated other minerals. The relationship of birnessite and rancieite was studied by means of X-ray powder diffraction and infrared absorption spectroscopic analyses. It is assumed that these minerals are closely related to each other in crystal structure, but separate species. The manganese oxide minerals were formed mainly by replacement, precipitation from solution, and recrystallization in the supergene weathering environment. The trend of formation of manganese oxide minerals is: (Rhodochrosite)-(todorokite)-(birnessite, rancieite)-(nsutite, pyrolusite, chalcophanite).

• Journal of Korea Foundry Society
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• v.35 no.1
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• pp.8-14
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• 2015

Variations of nickel contents and microstructures in molten magnesium alloys on the addition of aluminum, zirconium, and manganese have been investigated. Specimens were prepared by melting under $SF_6$ and $CO_2$ atmosphere and casting into a disc of 29 mm diameter with 7~10 mm thickness from the melt acquired at the top of crucible. Before casting, the molten metal was stirred for 3 minutes after each addition of alloying elements and maintained for 30 minutes for settling down. Results showed that zirconium did not significantly affect the content of nickel while aluminum remarkably reduced it by forming $Al_3Ni_2$ phase. When manganese are added to Mg-1wt%Ni alloy along with aluminum, both elements remarkably reduced the content of nickel. The addition of 1.5 wt% manganese to Mg-1wt%Ni alloy containing aluminum further reduced the content of nickel by more than 30%, during which an additional intermetallic phase $Al_{10}Mn_3Ni$ was precipitated in the molten magnesium.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.5
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• pp.283-292
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• 2004

The effects of the annealing parameters on microstructures were examined in a cold-rolled high strength steel containing 0.1% C, 0.5% Si, 1.5% Mn, and 0.04% Nb. It was impossible to avoid martensite in the microstructure even though the continuous annealing parameters were controlled. This indicates that the alloying elements such as silicon and manganese contributing to manganese equivalent($Mn_{eq}$) should be reduced to produce the ferrite-pearlite microstructure for the solid solution and precipitation hardened steel. It was found that a decrease in the rapid cooling temperature to $520^{\circ}C$ was effective to change the microstructure from ferrite-martensite to ferrite-pearlite-martensite. Typical dual-phase properties exhibiting a low yield ratio and a continuous yielding behavior were obtained when the rapid cooling temperature was in the range of $680^{\circ}C$ to $600^{\circ}C$. The critical volume fraction of martensite for the typical properties of dual-phase steel was about 11 percent.

• Resources Recycling
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• v.6 no.4
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• pp.11-16
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• 1997

The wastewater resulted from the process of developing and fuing for x-ray film manufachlring contains a lot of silvercomponent. The average concentation of silver-component is about 1,500 mgA. The wastewater contained silver-component is toxic when it is discharged to the natural ecosystem. So that we must to do pretreatment of wastewater prior to discharge. There are electrolysis. chemical precipitation, and metallic replacement as conventional lreabent proccss of fixer wastewater of x-ray film. Adsorption of silver-component in x-ray fkcr wastewater was carricd out this study. 'Ille manganese dioxide (MDO) reagent and the recovered manganese dioxide (RMDO) from the waste dry-cell were used for adsarbents. Adsorption of silvercomponent was wrried out at the batch and continuous type experimental equipment. The adsorption experiment results were obtained bom silver-component have some diifcrences according to adsorhents. The adsorption results of manganese dioxide reagent (MDO) were better ihan those of waste dry-ccU (RMDO), but the manganese dloxide recovered fmm waste dry-cell (RMDO) will be able la recognized as good adsorbent too.

• Journal of the Korean Society for Heat Treatment
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• v.23 no.6
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• pp.338-343
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• 2010

Mechanical properties and microstructures of medium carbon high manganese steels were investigated in terms of alloying elements such as Mn, C contents, and heat treatment condition. Austenite volume fraction was increased with increasing Mn content, leading to hardness decrease in the range of Mn content of above 10% after quenching and tempering. Such results are also supported by microstructural analysis and X-ray diffraction in that the increase in mangaese content results in the increase in austenite fraction. Studies on tempering condition indicated that not only hardness and tensile strength but also charpy impact values were reduced as tempering temperature were raised in the range of $250^{\circ}C$ to $600^{\circ}C$. It was also observed that fracture mode was changed from dimple to intergranular fracture. Such results are thought to be due to very fine carbide precipitation or impurity segreagation at grain boundaries as tempering temperature goes up. Heat treatment of Fe-5Mn-2Si-1Al-0.4C can be optimized by austenitizing at $850^{\circ}C$, air cooling and tempering at $250^{\circ}C$, resulting in 1950 MPa in Tensile strength, 17% in elongation and 23.3 $J/cm^2$ in charpy impact energy with high work hardening characteristics.

• Journal of Microbiology
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• v.43 no.6
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• pp.503-509
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• 2005

The production of manganese peroxidase (MnP) by Irpex lacteus, purified to electrophoretic homogeneity by acetone precipitation, HiPrep Q and HiPrep Sephacryl S-200 chromatography, was shown to correlate with the decolorization of textile industry wastewater. The MnP was purified 11.0-fold, with an overall yield of $24.3\%$. The molecular mass of the native enzyme, as determined by gel filtration chromatography, was about 53 kDa. The enzyme was shown to have a molecular mass of 53.2 and 38.3 kDa on SDS-PAGE and MALDI-TOF mass spectrometry, respectively, and an isoelectric point of about 3.7. The enzyme was optimally active at pH 6.0 and between 30 and $40^{\circ}C$. The enzyme efficiently catalyzed the decolorization of various artificial dyes and oxidized Mn (II) to Mn (III) in the presence of $H_2O_2$. The absorption spectrum of the enzyme exhibited maxima at 407, 500, and 640 nm. The amino acid sequence of the three tryptic peptides was analyzed by ESI Q- TOF MS/MS spectrometry, and showed low similarity to those of the extracellular peroxidases of other white-rot basidiomycetes.