• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.05a
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• pp.23-27
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• 2005

Electrogenerated chlorine leaching of used printed circuit board was Investigated in hydrochloric acid solution. The used printed circuit board contained about 45% of metal component, in which copper was about 84%. The leaching rate was greatly effected by current density and agitation. Utilization of electrogenerated chlorine was enhanced by increasing agitation and lowering current density. Leaching of copper was suppressed, while the minor metal elements, such as aluminum, lead, and tin, dominated the leaching at the initial stage.

• Korean Journal of Microbiology
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• v.11 no.4
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• pp.189-195
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• 1973

With the gradual expansion of copper demands, the utilization of enormous tonnages of waste copper mineral containig up to 0.5% copper becomes available. In order to investigate the possibilities on the application of bacterial leaching method to waste dumps or abandoned mines, the authors had carried out microbial leaching of copper minerals by F.ferrooxidans isolated from the Dalsung copper mine water. The results obtained were as follows : 1. The copper extraction rate from the Dalsung chalcopyrite has been a little accerelated by using flasks in place of percolators. 2. The percentage of copper extracted from the Dalsung chalcopyrite sample was 100% in 30 days in the presence of iron-oxidizing bacteria F.ferrooxidans while 9.27% in the absence of bacteria. 3. F.ferroxidans was capable of producing sufficient quantities of ferric sulfate and sulfuric acid from ferrous iron to bring about the dissolution of 100% of copper from the Dalsung chalcopyrite.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.2
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• pp.213-217
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• 2008

The objective of this research is to investigate the leaching characteristics of unregulated heavy metals such as Ni, Zn, Ba, Be, Sb, Se, V in specified waste. 108 waste samples which were taken from the representative facilities emitting hazardous substances, were analyzed. The rate of leaching of heavy metal was measured using an official test method. From the results, wastewater treatment sludge and dust contained much Ni, and Zn was detected in all samples. Dust and waste catalyst producted from petroleum-refining process tended to reveal V in high concentration. Ba, Be, Sb, Se showed low concentration, but require additional analyses of waste generated at different industries.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.73-82
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• 2004

This paper studies the leaching behaviors of pyrochlore-rich synroc incorporated 46.8wt% simulated actinides waste under the five simulated geological disposal media, which included the bentonite, granite, granite ＋ ferroferric oxide, granite ＋ cement, bentonite ＋ ferroferric oxide, respectively. The mass loss rates reached to equilibrium after 182 day and was 10-7 g/$\textrm{mm}^2{\cdot}d$. That suggests the mass loss rate of pyrochlore-rich synroc, loaded 46.8wt% actinides waste, was very low. The surfaces of the leached specimens were analyzed by XRD, SEM/EDS. The experimental results show that the pyrochlore-rich synroc samples in the systems, which contained bentonite and cement, have two new phases formed on the leached specimens surface at $90^{\circ}C$ for 728d; The bentonite and cement can retard the elements leaching; $Fe_3O_4$ can speed the elements leaching; Expect for Ti ion depleted on the sample surface, other ion, such as U, Zr, AI, Ca, were in equable states and Ba ion was enriched during test time, which indicated the simulated disposal media have good ability to retard the leaching behavior of the pyrochlore-rich synroc.

• Journal of Environmental Science International
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• v.12 no.3
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• pp.325-335
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• 2003

An agricultural land application of swine slurry is one of the best management practices in Jeju island whose ground water must be protected. So as to study the effect of appling swine slurry on ground water or aquifer, incubation-leaching technique was used by assuming the incubating period of 1, 2, 4, 8, 16, or 32 days, and application rate of 3200.0 mgT-N/$\ell$ , 820.0 mgT-P/$\ell$, and 1887.0 mgK$\^$+/$\ell$ in swine slurry. The leachates were collected from the soil columns(PVC 30 cm L${\times}$5.5 cm D) packed 15cm in depth with Gangjeong soil series by washing with 100 mL distilled water. The leached components were measured by using ion chromatography far Cl$\^$-/, NO$_3$-N, F$\^$-/, Br$\^$-/, Na$\^$+/, K$\^$+/, Ca$^2$$\^$+/, and Mg$^2$$\^$+/ , atomic absorption spectrophotometry for Fe and Mn, and UV-Vis spectrophotometry for T-N and T-p. Application of swine slurry in naked soil could influence on the ground water or aquifer by increasing nitrate-nitrogen in leachate with time, or leaching the cations present in soils in accompany with anions because of H$\^$+/produced in nitrification. Therefore, careful consideration should be taken about what amount, when, where, and how fur protecting ground water system.

• Nuclear Engineering and Technology
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• v.22 no.4
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• pp.315-325
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• 1990

The analytical repository source term (REPS) computer code is developed for the safety assessment of radioactive waste geologic repository. For reliable prediction of the leach rates for various radionuclides, degradation of concrete structures, corrosion rate of waste container, degree of corrosion on the container surface, and the characteristics of radionuclides are considered in this REPS code. For the validation of the radionuclide leach rates predicted by the REPS model, the calculated leach rates of Cs-137, Sr-85, and Co-60 are compared with two reported leaching test results. Cesium and strontium leach congruently, and the leaching test results of these species can be reproduced by the congruent leaching model included in the REPS model. In case of cobalt, the solid diffusion model is in good agreement with the leaching test results.

• Resources Recycling
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• v.26 no.5
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• pp.77-84
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• 2017

White and black dross are resulted from the recycling of aluminum. There are no established processes to recover valuable materials from black dross. Hydrometallurgical processes seem to be suitable for the treatment of aluminum dross. The salts in the black dross are recovered by dissolving with water. The residues are treated by either alkaline or acid leaching. Although the leaching rate of alumina by NaOH is lower than that by acid, its intermediates are more suitable to the production of alumina-based materials. The future direction for the treatment and recovery of valuable materials from aluminum dross is discussed.

• Journal of Bio-Environment Control
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• v.16 no.3
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• pp.269-273
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• 2007

Freezing hardiness of winter bud and branch according to dormancy level and low temperature, in persimmon (Diospyros kaki) cultivars, was investigated by electrolyte leaching rate, triphenyltetrazolium chloride (TTC) test, and sprouting. Electrolyte leaching rate was lowest in branch of 20th January and was highest in the 20th March. The electrolyte leaching rate of 'Fuyu' and 'Cheongdobansi' was high in the 20th January and was low in the 20th February, but 'Uenishiwase' and 'Nishimurawase' was opposed to that. 'Hachiva' was the middle level in the cultivars. Absence rate by TTC test was highest in the 20th January and was low in the others. The 20th March had a great decrease in $-10^{\circ}C$ treatment. The absence rate of 'Fuyu' and 'Uenishiwase' was low in the 20th January and March and was high in the 20th February. 'Nishimurawase' and 'Hachiya' had a high level irrespective of dormancy level. Sprouting was highest in the 20th February and was lowest in 20th March. Most cultivars were not sprout in $-20^{\circ}C$ treatment and 'Fuyu', 'Nishimurawase' and 'Cheongdobansi' was a little high level irrespective of dormancy level. 'Hachiya' was only high in the 20th January. Thus, freezing hardiness of persimmon was very weak low temperature after dormancy breaking and was not different between astringent and non-astringent persimmon.

• Journal of Radiation Protection and Research
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• v.10 no.2
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• pp.113-121
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• 1985

For the safety assessment of radwaste treatment and disposal, the leaching characteristics of $Cs^+\;and\;Sr^{++}$ from the cement-solidified radwastes was investigated by means of the survey and analysis of the activity leach rate and cumulative leach fraction of $^{137}Cs\;and\;^{90}Sr$ leaching from solidified radwastes. The cylindrical cement-solidified samples were made by the sodium silicate method and neutralization method changing the mole density of simulated liquid radwaste, type of cement, adding material and concentration of boric acid. The leaching study was carried out by the method using simulated PWR concentrated liquid radwaste solidified in cement that had been processed following the recommendations of IAEA. All the experimental results are in well accordance with the research data reported previously, but the watertight cement-solidified radwastes show rather high leach rate of radioactivity. It is learned, therefore, that the watertight cement is not adequate as the material for the solidified radwastes.

• Journal of the Mineralogical Society of Korea
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• v.28 no.3
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• pp.233-244
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• 2015

In order to study the phase transformation of pyrite and to determine the maximum Fe leaching factors, pyrite samples were an electric furnace and microwave oven and then ammonia leaching was carried out. The rim structure of hematite was observed in the sample exposed in an electric furnace, whereas a rim structure consisting of hematite and pyrrhotite were found in the microwave treated sample. Numerous interconnected cracks were only formed in the microwave treated sample due to the arcing effect, and these cracks were not found in the electric furnace treated sample. Under XRD analysis, pyrite and hematite were observed in the electric furnace treated sample, whereas pyrite, hematite and pyrrhotite were found in the microwave treated sample. The results of the pyrite sample leaching experiments showed that the Fe leaching was maximized with the particle size of -325 mesh, sulfuric acid of 2.0 M, ammonium sulfate of 1.0 M, and hydrogen peroxide of 1.0 M. The electric furnace and microwave treated samples were tested under the maximum leaching conditions, the Fe leaching rate was much greater in the microwave treated sample than in the electric furnace treated sample and the maximum Fe leaching time was also faster in the microwave treated sample than in the electric furnace treated sample. Accordingly, it is expected that the microwave heating can enhance (or improve) Fe leaching in industrial minerals as well as pyrite decomposition in gold ores.