• Resources Recycling
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• v.29 no.3
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• pp.11-23
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• 2020

This study aims to investigate breakage and liberation characteristics of iron ore from Shinyemi mine, Jeongseon by ball mill. Parameters of breakage functions for three grade samples of iron ore were obtained using single-sized-feed breakage test and back-calculation based on nonlinear programming. The results showed that with the increase in the grade of iron ore, the breakage rate factor decrease whereas the particle size sensitivity decreases. This results from retardation of microcrack-propagation by magnetite grain in the ore. Breakage distribution analysis showed that the breakage mechanism appear to be impact fracture dominant with the increase of grade owing to the stress distribution effect by magnetite grain. Degree of liberation (DOL) increased with the increase in grade and decrease in particle size, respectively. Using the breakage function and size-DOL relationship, a model that can predict time-dependent-DOL is established. When scale-up factors from operating condition are available, the model is expected to be capable of predicting size and DOL with time in actual mining process.

• Journal of Korean Medical classics
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• v.22 no.3
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• pp.321-336
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• 2009

Objectives : The purpose of our study was to discuss about the scholarship value and contents of the transcription of Correction of the Classic of Materia Medica that was obtained recently. Methods : We analysed the transcription of Correction of the Classic of Materia Medica itself and compared form and matter with Shennong's Classic of Materia Medica[神農本草經], Compendium of Materia Medica[本草綱目]. Results : 1. It is obvious that the transcription of Correction of the Classic of Materia Medica is one of the book works of Lee Gyujun. 2. The transcription of Correction of the Classic of Materia Medica was written to recover the original figure of Shennong's Classic of Materia Medica standing on Compendium of Materia Medica. Lee Gyujun corrected qi, flavor and main effects of herbs according to his medical sight, and classified herbs into three grade. Conclusions : The transcription of Correction of the Classic of Materia Medica is not an original book but an interim book on working process. But it reflects the medical sight of Lee Gyujun and the medical level of those days sufficiently. Also it is the only study of Shennong's Classic of Materia Medica in Chosun dynasty.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.383-395
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• 2008

To enhance the grade and recovery rate of the gold/silver ores which yield at Philippine Mankayan mine, we studied the characteristics which are the geologic and mineralogical features of gold and silver ore, the liberation by crushing and grinding, the separation by sieving and shaking table. Gold/silver ore is composed of the sulfide minerals like pyrite, sphalerite, galena; and the gangue minerals which is quartz, clay. Gold/silver element are mainly contained in a sulfide minerals like pyrite, sphalerite and galena. To increase the liberation rate of sulfide minerals containing gold/silver element, the gold/silver ore has to be grounded under $100{\mu}m$ very finely because the crystal size of sulfide minerals is distributed from $1{\mu}m$ to $100{\mu}m$. The liberation rate of gold/silver ore increases to 92% when the particle size ($d_{90}$) of ore is grounded below $100{\mu}m$ by jaw crusher $\to$ cone crusher $\to$ rod mill by steps. The grade and recovery of sulfide minerals could not be enhanced by sieving separation because those crystal size is distributed homogeneously below $100{\mu}m$. But, when we separated the sieved ore using shaking table, the gold and silver grade increased to 40 ppm and 140 ppm, respectively. Then the recovery rate of gold reach almost 100% but that of silver is no more that 50%.

• Journal of the Mineralogical Society of Korea
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• v.30 no.4
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• pp.137-147
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• 2017

Sericite is a clay mineral that has a wide applications in the industry, depending on its purity. To maintain sericite's purity as high as possible it is necessary to remove its gangue minerals or control their contents prior to use for high value-added products and applications. In this study, the wet beneficiation of sericite by applying selective grinding and sedimentation techniques, were investigated. The ore mineral was composed mainly of sericite, quartz and calcite. Analysis showed that the content of sericite increased along with the particle size decrease, but the contents of impurity minerals as quartz and calcite were tended to decrease relatively with particle size decrease. The results of liberation tests using an attrition scrubber showed that the increase in residence time and slurry density have increased the generation of fine particles in -325 mesh size range. It was observed, however, that the contents of impurities such as quartz and calcite in such fine particles also increased during prolonged scrubbing. In the dispersed form without breaking, the yield of the recovered concentrate was 15.4 wt% and the $K_2O$ content was 9.84 wt%, after the dispersed slurry was allowed to settle for 20 minutes. On the other hand, the concentrate yield was increased to 23.4 wt% after 10 minute attrition scrubbing and 40 minute sedimentation, while its $K_2O$ content was decreased to 9.71 wt%. Most of final products were observed as platelet-shaped particles containing Si, Al and K which are main component of sericite.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1171-1171
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• 2001

Quantitative analysis is an important requirement in exploration, mining and processing of minerals. There is an increasing need for the use of quantitative mineralogical data to assist with bore hole logging, deposit delineation, grade control, feed to processing plants and monitoring of solid process residues. Quantitative analysis using X-Ray Powder Diffraction (XRD) requires fine grinding and the addition of a reference material, or the application of Rietveld analysis to XRD patterns to provide accurate analysis of the suite of minerals present. Whilst accurate quantitative data can be obtained in this manner, the method is time consuming and limited to the laboratory. Mid infrared when combined with multivariant analysis has also been used for quantitative analysis. However, factors such as the absorption coefficients and refractive index of the minerals requires special sample preparation and dilution in a dispersive medium, such as KBr to minimize distortion of spectral features. In contrast, the lower intensity of the overtones and combinations of the fundamental vibrations in the near infrared allow direct measurement of virtually any solid without special sample preparation or dilution. Thus Near Infrared Spectroscopy (NIR) has found application for quantitative on-line/in line analysis and control in a range of processing applications which include, moisture control in clay and textile processing, fermentation processes, wheat analysis, gasoline analysis and chemicals and polymers. It is developing rapidly in the mineral exploration industry and has been underpinned by the development of portable NIR spectrometers and spectral libraries of a wide range of minerals. For example, iron ores have been identified and characterized in terms of the individual mineral components using field spectrometers. Data acquisition time of NIR field instruments is of the order of seconds and sample preparation is minimal. Consequently these types of spectrometers have great potential for in-line or on-line application in the minerals industry. To demonstrate the applicability of NIR field spectroscopy for quantitative analysis of minerals, a specific example on the quantification of lateritic bauxites will be presented. It has been shown that the application of Partial Least Squares regression analysis (PLS) to the NIR spectra can be used to quantify chemistry and mineralogy in a range of lateritic bauxites. Important, issues such as sampling, precision, repeatability, and replication which influence the results will be discussed.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.4
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• pp.34-41
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• 2013

In this study, we investigated the physical properties of powders made from agricultural byproducts, including rice straw, peanut husks, and garlic stems, to manufacture a new organic filler used for making paperboard. These materials were collected individually, and then we measured their chemical compositions. The byproducts were ground with a laboratory grinder and fractionated with 60-, 100-, and 200-mesh sieves to make many grades of organic fillers. After the grinding and fractionation, the yield, mean particle size, and particle size distribution of each grade were measured. Particle shapes were also investigated using a scanning electron microscope. The organic filler made from rice straw had the highest yield of the largest particle size group and higher contents of cellulose and hemicellulose than those made from peanut husks and garlic stems. The rice straw also showed more regular particle shapes and a lower aspect ratio than the other agricultural byproducts.

• Safety and Health at Work
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• v.2 no.4
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• pp.336-347
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• 2011

Objectives: In Korea, an average of 258 workers claim compensation for their noise-induced hearing loss (NIHL) on an annual basis. Indeed, hearing disorder ranks first in the number of diagnoses made by occupational medical check-ups. Against this backdrop, this study analyzed the impact of 19 types of noise-generating machines and equipment on the sound pressure levels in workplaces and NIHL occurrence based on a 2009 national survey on work environments. Methods: Through this analysis, a series of statistical models were built to determine posterior probabilities for each worksite with an aim to present risk ratings for noise levels at work. Results: It was found that air compressors and grinding machines came in first and second, respectively in the number of installed noise-generating machines and equipment. However, there was no direct relationship between workplace noise and NIHL among workers since noise-control equipment and protective gear had been in place. By building a logistic regression model and neural network, statistical models were set to identify the influence of the noise-generating machines and equipment on workplace noise levels and NIHL occurrence. Conclusion: This study offered NIHL prevention measures which are fit for the worksites in each risk grade.

• Resources Recycling
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• v.33 no.2
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• pp.37-45
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• 2024

Molybdenum is used in various industries because of its high heat and corrosion resistance. It was selected as a critical mineral in Korea. However, there have been recent challenges in production because of the increased depth and decreased grade of molybdenum veins. Consequently, it is necessary to enhance the effectiveness of the molybdenum beneficiation process. In this study, a basic evaluation of beneficiation characteristics was conducted to enhance the effectiveness of the domestic molybdenum ore beneficiation process. The properties of the beneficiation process were assessed using mineralogical analysis, work index, and flotation kinetics. The results revealed that the allowable particle size of the molybdenum ore for liberation was ~100 ㎛. In addition, the work index was calculated to be 14.57 kWh/t. The operating conditions in the flotation units were achieved by determining the optimal flotation time for each process based on flotation kinetics. Finally, the characteristics of molybdenum ore beneficiation provided in this study can be utilized to diagnose the grinding and flotation processes of large-scale molybdenum beneficiation plants.

• Korean Journal of Food Science and Technology
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• v.24 no.5
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• pp.408-413
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• 1992

This study was conducted to determine the effect of the homogenizing grade of sample on absorbance of near infrared reflectance spectrophotometer with which chemical compositions of food were rapidly and effectively analyzed. By the mathematical treatment of absorbance values standard error of prediction was reduced as follows. 1. The absorbance values of various samples ground for the same periods of time were calibrated before or after treatment with first or second derivative in an attempt to accurately predict the components of samples ground for the different periods of time. The standard error of prediction for moisture content were 1.478%, 0.658% and 0.580%, respectively, those for fat content 0.949%, 0.637% and 0.527%, respectively, and those for protein content 0.514%, 0.493% and 0.394%, respectively. Calibration of absorbance values after second derivative treatment showed the highest accuracy in predicting sample components. 2. The absorbance values of various samples ground for the different periods of time were calibrated before or after treatment with first or second derivative in order to accurately predict the components of samples ground for the different periods of time. The standard error of prediction for moisture content were 1.026%, 0.589% and 0.568%, respectively, and those for protein content 0.860%, 0.557% and 0.399%, respectively. The standard error of prediction were lower in the order of calibrations before and after first and second derivative treatments. As a result, calibration of absorbance values after second derivative treatment showed higher accuracy regardless of grinding time of samples.

• Journal of Animal Science and Technology
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• v.45 no.3
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• pp.397-408
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• 2003

This study was conducted to examine the feeding effects of FFWBG (fermented feedstuff with wet brewer’s grain) and GS(grinding soybean) in Hanwoo steers. For this research, total twenty steers(average body weight : 455.7$\pm$25.9kg) were grouped into control(formula feed), T1(formula feed:FFWBG=60:40), T2(formula feed:GS=80:20), T3(formula feed:FFWBG:GS=50:40:10), and T4(formula feed: FFWBG:GS=40:40:20), each treatment was allocated to four steers. There was a tendency to be increased average daily gain in T1, T2, T3 and T4 compared with the control even though no statistical significance was found. The feed conversion of T1, T2, T3 and T4 were beneficially better than that of control(P<0.05; 8.25, 9.44, 6.69 and 7.71 vs 11.90, respectively). The blood urea nitrogen concentration of T4 was higher than that of control(P<0.05), but the creatinine concentration of T4 was lower than that of control(P<0.05). The glucose concentration of T1, T2, T3 and T4 were higher than that of control(P<0.05; 59.39, 62.44, 62.17 and 54.00 vs 51.00mg/$d\ell$, respectively). The back-fat thickness of T3 was thicker than that of control, T1, T2 and T4. The rib-eye area of T1, T3 and T4 was wider than that of control. Appearances percentage of ‘A’ ranked meat quantity were 66, 33, 75 and 33% in control, T1, T2 and T4, respectively.