• Korean Journal of Materials Research
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• v.8 no.11
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• pp.1038-1042
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• 1998

Mechanical grinding and subsequent annealing were applied to the $Nd_5Pr_7Fe_{82}B_6$ and $Nd_{12}Fe_{82}B_6$ ingots, and the crystal structure and magnetic properties were investigated. After 330 hours milling, the particles with $2~3\mu\textrm{m}$average size were identified to be composed of very fine crystallites judging from the x-ray diffraction patterns. The intrinsic coercivity of 18.36 ~ 18.79 kOe and the maximum energy product of 8.32-8.38 MGOe were obtained by the annealing of the milled powders at $600^{\circ}C$ for 2 hours. Annealing at a higher temperature resulted in the improved magnetic properties. However it was revealed that the control of the micro-crystallites formed during the grinding process was more important to get an optimized magnetic properties than the annealing condition.

• Resources Recycling
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• v.15 no.6 s.74
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• pp.48-55
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• 2006

This study was carried out for establishing the physical recycling technique for commercializing process on household batteries. The procedure involves shape separator, crushing, magnetic separation, classification and eddy current separation in sequence. The separation capacity was 400-600 unit cell/hr with shape separation system. The impurities such as manganese and zinc in the magnetic product were below 0.1% respectively, the concentration of iron was above 99% in spent carbon zinc battery. Also non-magnetic products are composed of 22-30% En, 16-22% Mn, 1-3% Fe in the case oi spent zinc carbon battery. The amounts of other components such as carbon rod, plastics and separator were about 37-50%. From the eddy current separation of nonferrous products, the plate-type zinc components were separated up to 96% with 2,250-2,750 meter/min of the conveyor speed.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.281-295
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• 2010

This paper deals with magnetic susceptibility, mineralogy, soil properties (pH, EC, CEC, loss on ignition), iron and manganese oxides, the content and partitioning of heavy metals (As, Cd, Cr, Cu, Ni, Pb, Zn), and their mutual relationship in the soil samples of an unpolluted, abandoned mine area, and industrial complex area. The various minerals derived from weathered bedrock were identified by X-ray diffraction in the unpolluted soil samples, except for the magnetic minerals. XRD analysis also revealed the existence of hematite and magnetite related to mine tailings and waste rocks in the abandoned mine area samples. The industrial complex area samples had carbonate minerals, such as calcite and dolomite, that might be due to anthropogenic deposition. The sum of the reducible, oxidizable, and residual fractions was over 80% for the abandoned mine area samples and over 50% for the industrial complex area samples using the sequential extraction method. The industrial complex area samples had a relatively high carbonate fraction that was associated with carbonate minerals. The content of aqua regia-extractable Fe, Mn, As, and Zn had a high positive correlation with the content of the dithionite-citrate-bicarbonate (DCB)-extractable method related to Fe/Mn oxide phases. The 54% and 58% of aqua regia-extractable Fe and As content, respectively, acted together with the concentrations of the DCB-extractable phases. Magnetic susceptibility values of total samples ranged from 0.005 to $2.131{\times}10^{-6}m^3kg^{-1}$. The samples including iron oxide minerals, such as hematite and magnetite, had a high magnetic susceptibility. The magnetic susceptibility showed a significant correlation with the heavy metals, Cd (r=0.544, p<0.05), Cr (r=0.714, p<0.01), Ni (r=0.645, p<0.05), Pb (r=0.703, p<0.01), and Zn (r=0.496, p<0.01), as well as Fe (r=0.608, p<0.01) and Mn (r=0.615, p<0.01). The aqua regia-extractable Fe and Mn content had a significant positive correlation with Cd, Cr, Cu, Ni, and Zn. However, the DCB-extractable Fe and Mn content had a significant positive correlation with As and Ni, indicating that the heavy metals were associated with Fe and Mn oxide minerals.

• Journal of the Mineralogical Society of Korea
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• v.24 no.1
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• pp.1-17
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• 2011

Mineralogical study was carried out for heavy minerals in the sea sand near Ongjingun bay, Kyonggi-do separated using the gravity and magnetic separators. Ilmenite, zircon and minor monazite and garnet were valuable minerals with gangue minerals of quartz, K-feldspar, plagioclase, muscovite, hornblende, epidote and chlorite. Quantitative analysis with SIROQUANT program showed that the contents of ilmenite separated with the gravity separation (the shaking table separation), the 1st step magnetic separation (rare earth magnetic separation) and the 2nd step magnetic separation (the Eddy current magnetic separation) were increased into 0.8, 18.3, and 48.7%, respectively. The content of ilmenite, monazite and zircon were recalculated based on the chemical composition of the representative and heavy fraction products of raw sand, the 1 step and 2 step gravity separations, and the 1 step and 2 step magnetic separations. The content increased to 0.23, 0.55, 5.22, 16.17, and 44.99% in ilmenite, 0.11, 0.02, 0.16, 0.51, and 1.19% in monazite. Although the zircon content did not differ over the processes (0.13, 0.12, 0.11, 0.15, and 0.10%), the improved recovery of zircon is expected by applying sieving process because of its high content (27%) in the fine grain size fraction (< 140#) of the 2 step gravity separation.

• Economic and Environmental Geology
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• v.53 no.2
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• pp.183-196
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• 2020

This study aimed to recover native gold from the concentrate using microwave-nitric acid leaching and magnetic/hydro separation experiments. The insoluble-residue was filtered from leaching solution through microwave-nitric acid leaching experiment. As a result of the atomic absorption spectrometer(AAS) analysis of the filtered leaching solution, it was discovered that Au content was not eluted at all and it was observed from the back scattered electron(BSE) image that native gold was liberated in the insoluble-residue. When magnetic/hydro separation experiments were applied for the insoluble-residue, magnetic and non magnetic minerals were separtated from insoluble-residue. Magnetite was recovered from the magnetic minerals and as a result of applying the hydro separation experiment again for the non-magnetic mineral, native gold was recovered. The native gold was identified through the X-ray diffraction(XRD) analysis and BSE image.

• Progress in Superconductivity and Cryogenics
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• v.18 no.1
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• pp.10-13
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• 2016

In this study, we developed a new volume reduction technique for cesium contaminated soil by magnetic separation. Cs in soil is mainly adsorbed on clay which is the smallest particle constituent in the soil, especially on paramagnetic 2:1 type clay minerals which strongly adsorb and fix Cs. Thus selective separation of 2:1 type clay with a superconducting magnet could enable to reduce the volume of Cs contaminated soil. The 2:1 type clay particles exist in various particle sizes in the soil, which leads that magnetic force and Cs adsorption quantity depend on their particle size. Accordingly, we examined magnetic separation conditions for efficient separation of 2:1 type clay considering their particle size distribution. First, the separation rate of 2:1 type clay for each particle size was calculated by particle trajectory simulation, because magnetic separation rate largely depends on the objective size. According to the calculation, 73 and 89 % of 2:1 type clay could be separated at 2 and 7 T, respectively. Moreover we calculated dose reduction rate on the basis of the result of particle trajectory simulation. It was indicated that 17 and 51 % of dose reduction would be possible at 2 and 7 T, respectively. The difference of dose reduction rate at 2 T and 7 T was found to be separated a fine particle. It was shown that magnetic separation considering particle size distribution would contribute to the volume reduction of contaminated soil.

• Proceedings of the Korean Magnetic Resonance Society Conference
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• 2002.08a
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• pp.72-72
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• 2002

In most traditional sorption study in environmental conditions, experimental sorption data have been measured and interpreted by empirical ways such as partition coefficient and sorption isotherms. A mechanistic understanding of heavy metal interactions with various minerals (metal oxides, clay minerals) in aqueous medium is required to describe the behavior of radioactive metal ions in the environment. Various spectroscopic methods provide direct or indirect information on sorption mechanisms involved. We applied EPR (Electron Paramagnetic Resonance) spectroscopy to investigate the nature of metal ion sorption at water/mineral interfaces using Cu(II) as a spin probe. The major sorbed species and their motional state was identified by their EPR spectra. They showed distinct signals due to their strength of binding, local structure and motional state. The EPR results together with macroscopic sorption data show that sorption involved at least three different mechanisms depending on chemical environments (1).

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2019.05a
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• pp.297-298
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• 2019

• Economic and Environmental Geology
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• v.16 no.3
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• pp.223-243
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• 1983

palaeomagnetism is a major implement to define tectonic provinces and to estimate their past relative position quantitatively. In this sort of investigation it is tacitly assumed that the magnetization of the rocks under study was acquired at the time of their formation. However, because of the possibility of secondary alteration and/or replacement of magnetic minerals, this assumption is not always legitimate. To secure reliable palaeomagnetic data it is therefore fundamental to identify the carrier mineral of magnetization. This paper reviews magnetic mineralogy relevant to palaeomagnetism of terrestrial rocks. Under the heading of each mineral its genesis, crystal structure, magnetic properties, criteria for ore microscopic determination and secondary alteration are summerized. This paper should also be helpful in application of magnetic mineralogy to geothermometry and oxygen barometry in igneous petrology, diagenesis and provenance study in sedimentary petrology, metamorphic temperature determination and genesis study of ore deposits.

• Journal of the Korean Magnetics Society
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• v.7 no.6
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• pp.293-298
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• 1997

$Fe_5Si_Xb_{5-x}$ (x=0, 1, 2, 3) powders were prepared by mechanical alloying, and their phases and magnetic properties were investigated by using XRD, TEM, Mossbauer spectroscopy and VSM. Starting elements are incorporated into $\alpha$-Fe in the early stage of mechanical alloying, and the stable phases are formed as the milling proceeds. After the annealing at 80$0^{\circ}C$ for 2 hours, it is found that the FeB and $Fe_2B$ phases coexist for the $Fe_5B_5$(x=0) composition. By substituting Si for B, the formation of $Fe_2B$ phase is restricted and the $Fe_5SiB_2$, $Fe_2Si_{0.4}B_{0.6}$ and paramagnetic phase begin to appear. The FeB phase has wide range of hyperfine magnetic field because it is not fully crystallized on the annealing at 800 $^{\circ}C$. On the contrary, others have good crystalline phases and show well-defined hyperfine magnetic field. Magnetic saturation is highest for the $Fe_5B_5$ composition where the amount of the $Fe_2B$ phase in large.