• Economic and Environmental Geology
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• v.53 no.2
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• pp.159-166
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• 2020

In this research, we investigate the effect of microwave pretreatment on the recovery of gold from the gold concentrates by thiourea leaching. The changes in mineral phases by decomposition of pyrites in the gold concentrates using microwave were observed, and the result of microwave irradiation showed that the temperature of the irradiated sample increases with increasing irradiation time. With the reaction of temperature increases, Sulfur (S) in pyrites was converted to sulfur dioxide (SO₂), and then the content of S in the sample was reduced. The analytical results of XRD and SEM-EDS showed that pyrites are converted to magnetite and hematite, and its surfaces are changed to a porous shape where micro-cracks are developed. The Au leaching efficiency from the irradiated gold concentrates using thiourea-mixed solvent increased with the increases of irradiation time and solvent concentration. The experimental results considering leaching parameters indicate that the mechanism of microwave irradiation increases the maximum leaching efficiency and leaching rate of the gold concentrates, and the solvent does a role for the increasing of leaching rate constant.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.05a
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• pp.40-44
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• 2004

• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.8-11
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• 1994

Disposal of hazardous ions in the aqueous streams is a significant industrial waste problem.. Waste streams from electronics, electroplating, and photographic industries contain metal ions such as copper, nickel, zinc, chromium(IV), cadmium, aluminum, silver, and gold, amongst others in various aqueous solutions such as sulfates, chlorides, fluorocarbons, and cyanides. Typical plating solutions having similar compositions are listed in Table 1. Spent process streams in catalyst manufacturing facilities also contain precious metals such as Ag, Pt, and Pd. Developing an effective recovery process of these metal ions for reuse is important.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.92-94
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• 2001

We investigated quench recovery characteristics of Au/YBCO thin film meander lines. YB$a_{2}$$Cu_{3}$ $O_{7}$films were coated in-situ with a gold layer and patterned into 2 mm wide meander lines by photolithography. The limiters were tested with simulated fault currents at various source voltages. Resistance decreased first slowly and then rapidly to zero. Resistance vs. time curves for different source voltages fell on top of each other when translated horizontally. The slowly varying portion of data fell on straight lines of a slope on a semi-log scale at all source voltages. A heat balance equation reflecting heat loss from meander lines to surroundings explains these results quantitatively.

• 한국지구물리탐사학회:학술대회논문집
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• 2009.05a
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• pp.35-45
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• 2009

Reservoir Characterization (RC) using 3-D seismic attributes analysis can provide properties of the oil sand reservoirs, beyond seismic resolution. For example, distributions and temporal bed thicknesses of reservoirs could be characterized by Spectral Decomposition (SD) and additional seismic attributes such as wavelet classification. To extract physical properties of the reservoirs, we applied 3-D seismic attributes analysis to the oil sand reservoirs in McMurray formation, in BlackGold Oilsands Lease, Alberta Canada. Because of high viscosity of the bitumen, Enhanced Oil Recovery (EOR) technology will be necessarily applied to produce the bitumen in a steam chamber generated by Steam Assisted Gravity Drainage (SAGD). To optimize the application of SAGD, it is critical to identify the distributions and thicknesses of the channel sand reservoirs and shale barriers in the promising areas. By 3-D seismic attributes analysis, we could understand the expected paleo-channel and characteristics of the reservoirs. However, further seismic analysis (e.g., elastic impedance inversion and AVO inversion) as well as geological interpretations are still required to improve the resolution and quality of RC.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.253-260
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• 2009

Gold stock could include the U.K. in the European economy by the alternative plan of the problems that it was occurred while nationalizing industry and a company for economic recovery and national profit after the World War Ⅱ and it was wide and came to open in the country of European most. However, the negation was sentenced to it for the reason of the gold stock which the U.K. adopted in European many countries infringing "freedom of the capital movement" at a European court of law. However, I consider gold stock positively to protect it from hostile M&A of the company of the national strategy from the Middle East and an Asian national rich fund recently in France and Germany. If our country looks straight at reality, Urstatut or the agreement of the majority stockholder have a very strict matter assuming the protection of the existing shareholder and must be able to gain the favor if you look by the flow of such world economy.

• Mycobiology
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• v.51 no.6
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• pp.379-387
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• 2023

In this study, twenty-five yeast strains were isolated from soil samples collected in the gold mining ore in Gia Lai, Vietnam. Among them, one isolate named GL1^T could highly tolerate Cu²⁺ up to 10 mM, and the isolates could also grow in a wide range of pH (3-7), and temperature (10-40 ℃). Dried biomass of GL1 was able to remove Cu²⁺ effectively up to 90.49% with a maximal biosorption capacity of 18.1 mg/g at pH 6, temperature 30 ℃, and incubation time 60 min. Sequence analysis of rDNA indicated this strain was closely related to Rhodotorula mucilaginosa but with 1.53 and 3.46% nucleotide differences in the D1/D2 domain of the 28S rRNA gene and the ITS1-5.8S rRNA gene-ITS2 region sequence, respectively. Based on phylogenetic tree analysis and the biochemical characteristics, the strain appears to be a novel Rhodotorula species, and the name Rhodotorula aurum sp. nov. is proposed. This study provides us with more information about heavy metal-tolerant yeasts and it may produce a new tool for environmental control and metal recovery operations.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.191-201
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• 2002

The Gubong gold-silver deposits if gold-silver-bearing hydrothermal massive quartz veins which were filled the fractures along fault shear (NE, NW) zones within Precambrian banded or granitic gneiss of Gyeonggi massif. Ore mineralization of this deposits is contained within a single stage of quartz vein which was formed by multiple episodes of fracturing and healing. Ore minerals are comported mainly of arsenopyrite, pyrite, sphalerite, chalcopyrite, galena with minor amounts of pyrrhotite, marcasite and electrum. The frequency and volume percentages of electrum associated with ore minerals from this deposits are recognized as follows; 44.5% and 54.3% with arsenopyrite, 24.3% and 33.8% with quartz, 12.6% and 0.1% with pyrite, 11.0% and 4.8% with galena, 5.0% and 7.0% with sphalerite and 2.5% and 0.02% with chalcopyrite, respectively. They show irregular (41.6%), subround (34.7%), elongate (17.0%) and granular (6.6%) shapes, respectively. Their grain size ranges from 2 to 150 um, but 90.9 percent of the grains are below 30 um. The chemical composition of electrums ranges from 26.39 to 72.51 Au atomic %. These composition (Au atomic %) on the basis of associated minerals are from 44.97 to 71.75 with arsenopyrite, pyrite, sphalerite and quartz, from 44.37 to 72.51 with quartz, from 35.40 to 41.01 with sphalerite and chalcopyrite, from 26.39 to 54.84 with pyrite, chalcopyrite, quartz and galena, from 28.49 to 53.28 with galena, respectively. We suggest that optimum recovery of gold would be obtained with reference to these results.

• Membrane Journal
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• v.13 no.1
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• pp.9-19
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• 2003

Membrane process was investigated to recover process water and valuable gold from washing water of electroless PCB plating processes. The filtration experiments were carried out using not only a RO membrane test cell to determine suitable membrane for washing water but also spiral wound membrane modules of nanofiltration and reverse osmosis for scale-up. At first, RO-TL(tap water, low pressure), RO-BL(brackish water, low pressure) and RO-normal(for water purifier) sheet membranes made by Saehan Co. were tested, and the performance of RO-TL membrane showed most suitable f3r recovery of soft etching, catalyst and Ni washing waters. As a result of RO test cell, the experiments for scale-up were carried out using RO-TL modules far water purifier at 7bar and $25^{\circ}C $The permeate flux fur Au washing water was about 30 LMH, but Au rejection was less than 80%. The permeate fluxes for Pd, Ni and soft etching washing water were about 22, 17 and 10 LMH, respectively. The Pd, Ni and Cu rejections showed more than 85, 97 and 98% respectively. The nanofiltration module for water purifier was introduced to recover Au selectively from Au, Ni and Cu ions in Au washing water. Most of Ni and Cu ions in the feed washing water were removed, and only Au ion was existed 81.9% in the permeate. Furthermore, Au ion in the permeate was concentrated and recovered by RO-TL membrane module. Finally, Au was also able to recover effectively by using 4 inch diameter spiral wound modules of NF and RO-TL membranes, in series.

• Journal of Environmental Science International
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• v.14 no.3
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• pp.335-343
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• 2005

The objective of this research is to evaluate a feasibility of wastewater reuse by membrane treatment with vibrating membrane separation equipment. Molecular weight of compounds in wastewater, permeability of membrane and retentate characterization after membrane filtration were investigated in order to determine appropriate membrane pore size and materials for wastewater treatment. Selected membrane was evaluated with vibration membrane separation equipment to optimize operating conditions. The following conclusion are drawn. 1. We got as following test results after the distribution of particles in the semiconductor wastewater, are made up of $1\~20{\mu}m$. Si, gold and Al in turn are contained in semiconductor wastewater. 2. Recovery rate is changeless under increasing recovery rate in operation. Though a value can be if pressure can be changed, the highest value of permeate rate is presented in 150 psi. 3. The AS-100(polysulpone) was selected as the most appropriate membranes for the treatment of semi-conductor wastewater to VSEP system. The fouling almost did not occur during this experiments. The analyses of treated water with VSEP system showed conductivity: 0.059,us/cm, TDS: 40mg/l, COD: 20mg/l, SS : 5mg/l, n-Hexane: 8.3mg/l. Comparing previous systems, operating expenses is decreased by more $50\%$.