• Resources Recycling
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• v.1 no.1
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• pp.51-57
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• 1992

The hydrochloric acid leaching has been studied as a fundamental experiment on the recovery of arsenic from arsenic-bearing copper slime in copper electrorefining. The slime is mainly composed of $\beta-Cu_3As$ Which is intermetallic compound of CU and As. And the minor components are $CU_2O$ and CusAs in the slime. The optimum conditions of leaching of the slime were found to be as follows : 6N hydrochloric acid, particle size passed through 140 mesh, leaching for 150 min at $60^{\circ}C$, ratio of HCI/slime of 3 to 1 ; where 98 percent of arsenic were leached out of the As-bearing slime.

• Resources Recycling
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• v.5 no.2
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• pp.45-51
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• 1996

Domestic coal contains approximnlely 03 to 7 percentage of sulfur. When the suliur in coal is burned, exhaust gas , nay be thc causc of air pollution problcms as well as acid rain. Thc government dccideil lo strengthen the environmcnlal protection policy a1 the 270 ppm of SO, for the coal-Ered plants and to stari in Ian. 1, 1999. This study was carried out lo rcmove the stlfur and mineral mancrs in the samplw using wet msg~xiic separatol ant1 oil agglomeration apparatus. The rcsults for the wet magnetic separalion showed that the total sulfur removal from Kangnung coal sample was 60.8% with 82.6% combustible recovery. For the results of oil agglomeration testa, combustible recavety, ash nod sulfur rcmovcl horn Maro coal sample were 98.0, 70.9 and 95.7 percent, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.8
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• pp.478-488
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• 2017

Stormwater filtration is widely used for the urban runoff treatment. However, intensive maintenance and lack of information about the performance have resulted in an increased need of proper evaluation. In this study, the performance of an upflow stormwater runoff filtration system, consisting of a supporting unit and a filtration unit filled with a ceramic media, was investigated. The maximum head loss increase was about 3 cm under the suspended solid (SS) load of $30kg/m^2$ and the SS removal was more than 96%, when the filtration velocity was 20-40 m/h. The head loss and the porosity of the media can successfully be described by a power model. It was confirmed that the a significant amount of SS can effectively be removed at supporting unit, minimizing SS load to the filter media bed. Several backwashing strategies have been tested to establish the optimum condition. It was found that the stagnant water discharge is important to minimize the SS release immediately after backwashing. Also, the filter bed loaded with $400-450kg/m^2$ SS can almost completely be washed to reduce the head loss to the that of empty bed. The results in this study indicate that the upflow ceramic media filter is an excellent alternative to stormwater treatment, with high SS removal and long lifespan.

• Journal of the Korean GEO-environmental Society
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• v.18 no.1
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• pp.23-29
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• 2017

This study, to provide quantitative data related to compaction characteristics, identifies the compaction characteristics of various types of soil samplers, in relation to their particle-size distribution and plasticity degree, and the compaction characteristics of artificially created granular materials, in relation to their A & D compaction. The results of the experiments show as follows. $r_{dmax}$ of clay is less than those of both sand and gravel approximately by 10%. O.M.C of clay has turned out to be greater than sand and gravel approximately by 20% and 30%, respectively. Changes in the compaction characteristics can be observed clearly around 30~60% of sand and 30~50% of passing No.200 sieve. It has also been shown that the compaction characteristics related to LL and PL are similar to each other in changes, and that the compaction characteristics become less clear with higher percent of fine grained soil. The compaction characteristics of the artificially created granular materials and field materials have appeared almost similar to each other. $r_{dmax}$ is less approximately by 30% and O.M.C greater approximately by 20% in A compaction than in D compaction. As $r_{dmax}$ and O.M.C become greater, its rate increases.

• Geotechnical Engineering
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• v.11 no.4
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• pp.63-74
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• 1995

Much of Taegu and Kyungpook areas are composed of sedimentary rocks. This paper is concerned with the engineering characteristi os of weathered shale soils and mudstone soils. In this study, the engineering characteristics of weathered shale soils and mudstone soils are investigated by performing tests such as compaction, gradation, CBR permeability and crushability according to compaction energy and water content. The experiments were carried out to obtain the relationships of the ratio of surface area(Sw'/Sw) and the indez of crushing(IC) The results are found as follows : (1) Weathered shale soils are larger than weathered mudstone soils in maximun dry den sixty, but weathered shale soils are smaller than weathered mudstone soils in OMC. (2) Minimum permeability is found in OMC's 1~2% wet side, and the more compaction energy is high, the more the change's range of permeability becomes narrow. (3) There is linear correlation between the ratio of surface area and the indez of crushing. IC : 14.286sw'/Sw -8.429(r=0.9937) (4) Soaked CBR value becomes maximum in OMC's dry side, and it decreases as the water content increases. Whereas the more compaction energy is high the more unsoaked and soaked CBR values are high in OMC's dry side, unsoaked and soaked CBR values are opposed to that in OMC's wet side.

• The Korean Journal of Food And Nutrition
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• v.25 no.3
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• pp.656-663
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• 2012

Two sorghum(Sorghum bicolor L. Moench cv. Hwanggeumchal-susu and Miryang 3) samples were milled using different milling methods, and their physicochemical properties were tested. Particle size was classified into five groups such as pin mill and low temperature-microparticulation(LTM; 10,000, 20,000, 30,000, and 40,000 rpm). The water absorption index (WAI), water solubility index(WSI), and a rapid Visco analyzer(RVA) were used to examine particle size distribution and color differences. Particle size of sorghum flour prepared using LTM was lower than that prepared using a pin mill. Particle size was further reduced by successive dry milling of the LTM flour. Lightness of colored pigments increased when particle size decreased. The WAI of Miryang 3 pin milling(M1) flour was the lowest after LTM, and WSI was higher in the order of M2, M3, M4, and M5. LTM sorghum flour had significantly higher pasting viscosity, as determined using a rapid Visco analyzer. LTM Miryang 3 sorghum flour(M2~M5) flour showed lower breakdown viscosity and higher final viscosity compared to those of M1 flour, resulting in an increased setback value.

• Journal of the Mineralogical Society of Korea
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• v.27 no.1
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• pp.53-62
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• 2014

In order to remove Fe impurity from low-grade pyrophyllite ore, the effect of certain variables such as particle size, concentration of sulfuric acid, amount of ammonium sulfate, added hydrogen peroxide, and temperature were studied. The euhedral cubic pyrites were observed in the low-grade pyrophyllite ore by reflected light microscopy, and quartz and dickite were identified in the sample by XRD analysis. The results of the Fe removal experiments showed that the best Fe removal parameters were when the particle size was at -325 mesh, the addition of $H_2SO_4$, $(NH_4)_2SO_4$ and $H_2O_2$ was at a 2.0 M, 10.0 g/l, and 3.0 M concentration, respectively, and at a $70^{\circ}C$ leaching temperature. In the dissolution kinetics analysis, the dissolution of Fe from the pyrite surface was a controlled chemical reaction, and the Fe dissolution reaction was proportioned to 0.066/R, $[H_2SO_4]^{1.156}$, $[(NH_4)_2SO_4]^{0.745}$, $[H_2O_2]^{0.428}$.

• Mineral and Industry
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• v.26
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• pp.13-21
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• 2013

This study is carried out experiments on various factors for improving the grade of low grade scheelite by Knelson concentrator prior to the main beneficiation process. Even though there are several gravity separators such as Jig, Spirals and etc. for rougher concentrate, the KC3 Knelson Concentrator was adopted to get better separation efficiency and beneficiating effects for pre-concentration of the low grade scheelite ore. The feed samples was prepared to minus 1mm in size by crushing and grinding. The important factors in the KC3 Knelson Concentrator test were examined in terms of the variations such as number of treatment, feed rate, rotation speed of bowl(G force), water flow rate, pre-removal of magnetic minerals, feed size and feed grade. According to the result of experiment, it shows that the important technical variations are limited in terms of number of treatment, feed rate, feed size and feed grade. The final result shows that the KC3 Knelson Concentrator obtains the scheelite pre-concentrate of about $3%WO_3$ grade and 90% recovery, respectively, from the feed containing about $0.8-1.0%WO_3$ grade.

• Journal of the Korean Geosynthetics Society
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• v.10 no.4
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• pp.113-121
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• 2011

River sand has generally used for the backfill material of underground power cables. The thermal resistivity of it has $150^{\circ}C$-cm/Watt in wet condition and more than double in dry condition. The final goal of this study is to find the backfill material which has a small change in thermal resistivity with various water contents, for example thermal resistivity is $50^{\circ}C$-cm/Watt and $100^{\circ}C$-cm/Watt in wet and dry conditions respectively. In this study it is presented that the comparison of thermal resistivity using stone powder, crush rock, weathered granite soil and Jumunjin sand as well as river sand in the needle method regarding water content, dry unit weight and particle size distribution. As a result, the thermal resistivity of a material is minimized when they have maximum dry unit weight at optimum moisture content and maximum density by appropriately mixing materials for particle size distribution. Therefore thermal resistivity characteristics should be considered two factors: one is the difference between natural dry condition and dry state after optimum moisture content, and the other is the difference between unit weight of raw material and maximum dry density.

• Membrane Journal
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• v.18 no.1
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• pp.103-107
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• 2008

Membrane process has been focused as an alternative separation process because not only it exhibits a high selectivity compared with a traditional distillation process, but also it is known to be an energy saving separation process. Inorganic membrane, especially zeolite membrane, has been studied since it can be operated in severe conditions compared to the organic membranes. Recently, new zeolite materials are tested as an inorganic membrane material to overcome disadvantages of existing zeolite membranes. Kalsilite can be used as an inorganic membrane material for gas separation and selective water separation from water/organic mixtures because it is expected to be hydrophilic resulted from Si/Al ratio of 1 like zeolite 4A and has a narrow pore size of 0.36 nm. In this study, kalsilite was synthesized by a new economical hydrothermal process using Si : Al : K : $H_2O$ mole ratio of 1 : 1 : 8 : 60. The synthesized kalsilite powder was confirmed by XRD and has a mean diameter of $2.73{\mu}m$. The vapor adsorption test showed the synthesized kalsilite is hydrophilic.