• Progress in Superconductivity and Cryogenics
• /
• v.19 no.1
• /
• pp.17-21
• /
• 2017

Vanadium slags is a kind of vanadiferous solid waste from steelmaking process. It not only occupies land, pollutes environment, but also leads to waste of resources. Based on the difference of magnetic susceptibility of different particles caused by their chemical and physical properties from vanadium slag, a new technology, superconducting high gradient magnetic separation was investigated for separation and extraction of valuable substances from vanadium slag. The magnetic concentrate was obtained under optimal parameters, i.e., a particle size -200 mesh, a magnetic flux density of 0.8 T, a slurry concentration of 5 g/L, an amount of steel wools of 25 g and a slurry flow velocity of 2 L/min. The content of $Fe_2O_3$ in concentrate could be increased from 39.6% to 55.0% and $V_2O_5$ from 2.5% to 4.0%, respectively. The recovery rate is up to 42.9%, and the vanadium slag has been effectively reused.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.37-38
• /
• 2007

It needs several large reservoirs and long time to remove suspended solid like steel fines and iron oxide in hot rolling coolant. If removing rate of suspended solid in rolling coolant is improved by using high gradient magnetic separation (HGMS) system, the productivity of working process can be increased and the area of reservoir can be reduced. Pre-treatment process that react magnetic floc with inorganic and organic flocculant in coolant was studied. Horizontal type superconducting HGMS system was manufactured successfully, which was constituted with automatic filter transportation apparatus, 6 T He-free superconducting magnet system and water circulation system. The solid suspension removal ratio in hot rolling coolant was increased by flocculation with inorganic and organic flocculant.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.44-44
• /
• 2010

Conventional water treatment facilities like precipitation process need large-scale equipment and wide space to purify the wastewater of paper factory. In case of massive waste water, high gradient magnetic separation (HGMS) parts are more effective to purify it rapidly and to occupy relatively small space, since large voids at filter with HGMS are adopted. Cryo-cooled Nb-Ti superconducting magnet with room temperature bore in diameter of 100 mm and 600 mm in height was used for magnetic separator. Magnetic filters were designed by the analysis of magnetic field distribution at superconducting magnets.

• Journal of the Korean Ceramic Society
• /
• v.27 no.6
• /
• pp.769-776
• /
• 1990

This study deals with the refinement of Hwasun flint clay by grinding, classifying, magnetic separation and acid treatment in sequence. Results are as follows ; 1. Fine kaolinite particles of median size in the range of 4.8 and 1.7$\mu\textrm{m}$ was collected, with the yield of 87.4% by dry grinding and classifying process. 2. It is proven that the iron bearing are of Hwasun flint clay is mainly consisted of chloritoid and iron rich muscovite. 3. As the results of the high gradient magnetic separation, the bleaching and iron removal degree of the dry grinding and classifying sample was 4-58% and 5-62% respectively. 4. As the results of the acid treatment, bleaching and weight loss degree of the dry grinding and classifying sample was reduced to 16-82% and 6-29% respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.342-343
• /
• 2009

Paper factories use a large amount of water and same amount of wastewater is generated. It is important to purity and recycle the wastewater because of water shortages and water pollution. The existing water treatment facilities like precipitation process need large-scale equipment and wide space to purity the wastewater of paper factory. High gradient magnetic separation (HGMS) system has the merits to purity rapidly because of large voids at filter and to occupy small space. In this paper, two types of superconducting magnets were used for HGMS systems. Cryo-cooled Bi-2223 superconducting magnet system with 70 mm room temperature bore and 200 mm of height was prepared. Cryo-cooled Nb-Ti superconducting magnet with 100 mm room temperature bore and 600 mm of height was used for magnetic separator. Magnetic filters were designed by the analysis of magnetic field distribution at superconducting magnets. The various magnetic seeding reactions were investigated to increase the reactivity of coagulation. The effects of magnetic separation of wastewater were investigated as variation of magnetic field strength and flow rate of wastewater.

• Progress in Superconductivity and Cryogenics
• /
• v.23 no.3
• /
• pp.5-9
• /
• 2021

Comprehensive utilization of sulfur-containing iron tailings (SIT) not only solves environmental problems but also creates certain economic value. The iron element from SIT was enriched by the superconducting high gradient magnetic separation (S-HGMS) technology in this study. In the experiments, the total iron content (TFe) was increased from 26.3% to 60.5% with the total sulfur content (TS) of 5.9% under the optimal parameters, i.e., a magnetic flux density of 0.4 T, a slurry flow rate of 1500 mL/min. The high-quality sulfur-containing material with TFe of more than 60% was obtained, which can be used for preparing high-sulfur free cutting steel. The S-HGMS technology can realize the resource utilization of iron tailings with high added value.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.87-88
• /
• 2006

It is needed several large reservoirs and long time in order to remove suspended solid like steel fines and iron oxide at steel making factory. If removing rate of suspended solid in rolling coolant is improved, the productivity of working process can be increased and the area of reservoir can be reduced. Pre-treatment to add extra magnetization of suspended solid was studied Iron hydroxide and electrolytic dissociation were used for pretreatment. High gradient magnetic separation (HGMS) system was used for removing of magnetized suspended solid. Removing ratio showed over than 99% in the coolant containing magnetic fines. Magnetic properties of suspended solid were investigated after mixed with Al2(SO2)3 and organic flocculant by using electrochemical treatment.

• Progress in Superconductivity and Cryogenics
• /
• v.22 no.2
• /
• pp.17-20
• /
• 2020

Comprehensive utilization of tungsten tailings resources not only solves environmental problems but also creates huge economic benefits. The high content of iron impurity in tungsten tailings will have adverse effect on the downstream comprehensive utilization, whether flotation or pickling. In this paper, the Superconducting High Gradient Magnetic Separation(S-HGMS) is used to remove of Fe impurities from tungsten tailings. The optimal experimental parameters are as follows: background magnetic induction intensity is 3.0T, slurry flow velocity is 500ml/min. The Fe removal rate of Fe was 68.8% and the recovery rate was 59.53%.

• Investigative Magnetic Resonance Imaging
• /
• v.10 no.2
• /
• pp.108-116
• /
• 2006

Purpose : High-resolution spiral-scan imaging is performed at 3 Tesla MRI system. Since the gradient waveforms for the spiral-scan imaging have lower slopes than those for the Echo Planar Imaging (EPI), they can be implemented with the gradient systems having lower slew rates. The spiral-scan imaging also involves less eddy currents due to the smooth gradient waveforms. The spiral-scan imaging method does not suffer from high specific absorption rate (SAR), which is one of the main obstacles in high field imaging for rf echo-based fast imaging methods such as fast spin echo techniques. Thus, the spiral-scan imaging has a great potential for the high-speed imaging in high magnetic fields. In this paper, we presented various high-resolution images obtained by the spiral-scan methods at 3T MRI system for various applications. Materials and Methods : High-resolution spiral-scan imaging technique is implemented at 3T whole body MRI system. An efficient and fast higher-order shimming technique is developed to reduce the inhomogeneity, and the single-shot and interleaved spiral-scan imaging methods are developed. Spin-echo and gradient-echo based spiral-scan imaging methods are implemented, and image contrast and signal-tonoise ratio are controlled by the echo time, repetition time, and the rf flip angles. Results : Spiral-scan images having various resolutions are obtained at 3T MRI system. Since the absolute magnitude of the inhomogeneity is increasing in higher magnetic fields, higher order shimming to reduce the inhomogeneity becomes more important. A fast shimming technique in which axial, sagittal, and coronal sectional inhomogeneity maps are obtained in one scan is developed, and the shimming method based on the analysis of spherical harmonics of the inhomogeneity map is applied. For phantom and invivo head imaging, image matrix size of about $100{\times}100$ is obtained by a single-shot spiral-scan imaging, and a matrix size of $256{\times}256$ is obtained by the interleaved spiral-scan imaging with the number of interleaves of from 6 to 12. Conclusion : High field imaging becomes increasingly important due to the improved signal-to-noise ratio, larger spectral separation, and the higher BOLD-based contrast. The increasing SAR is, however, a limiting factor in high field imaging. Since the spiral-scan imaging has a very low SAR, and lower hardware requirements for the implementation of the technique compared to EPI, it is suitable for a rapid imaging in high fields. In this paper, the spiral-scan imaging with various resolutions from $100{\times}100$ to $256{\times}256$ by controlling the number of interleaves are developed for the high-speed imaging in high magnetic fields.

• Journal of the Mineralogical Society of Korea
• /
• v.7 no.2
• /
• pp.128-137
• /
• 1994

예산-공주-청양 지역에는 여러 큰 규모의 활석 광상이 분포한다. 이 지역에서 산출되는 활석 광석은 초염기성암 기원의 사문암이 열수변질작용을 받아서 주로 생성된 것으로알려져 있으며 녹니석, 운모, 각섬석 등의 규산염 광물들은 불순물로 다량 함유하고 있다. 활성 광석에 포함되어 있는 이들 함철규산염 광물들을 분리해 내고 활석 광석의 품질을 향상시키기 위하여 고구려배자력분리방법을 실험적으로 적용함으로써 활석 광석의 정제법을 강구하고자 하였다. 활석광석을 구성하고 있는 광물들의 자기적, 광물학적 특성을 토대로 하여 인공 혼합 표준 시료와 활석 광석 시료를 준비하고 이들을 대상으로 각각 실험하였다. 정제 실험 결과 고구배자력분리기를 통과한 정광의 경우 활석의 양이 증가하였고 다른 불순광물들의 양은 현저히 감소하였으며 활석 광석의 백색도에 있어서는 대흥광산의 원광석의 경우 60.6에서 65.5로, 평안광산의 경우 61.6에서 65.0으로, 신양광산의 경우 71.2에서 74.5로 향상되었다.