• 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%.

• Resources Recycling
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• v.19 no.6
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• pp.77-85
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• 2010

This study was carried out to develop a process flow sheet for recovering valuables (gold and high purity silica) from the gold mine tailings containing 1.7 g/ton of gold and 79.48 wt.% $SiO_2$. Float-sink tests using heavy liquids was conducted to explore the possibility of recovering gold by gravity separation. Hydrocyclone, froth flotation, and triboelectrostatic separatoin tests were conducted to recover high purity silica from the gold mine tailings. The results of float-sink tests showed that particles containing 5.58 g/ton of gold could be obtained at 2.72 specific gravity, but with very low yields around 3%. Meanwhile, all tests with hydrocyclone, froth flotation, and triboelectrostatic separation showed that high purity silica with $SiO_2$ content over 90% could be obtained. The purity could be improved further up to about 94% by employing several recleaning steps in the froth flotation and triboelectrostatic process.

• Resources Recycling
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• v.19 no.6
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• pp.61-69
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• 2010

S.M.C (DSME), only operating gold mine in Korea, is processing about 160 ton/day to recover gold and more than 150 ton/day of tailing is produced. Some portion of the tailings are used as a filler material after drying, but most of them are stored on the tailing dam. As a result of chemical analysis by a fire assay method, it contained Au 1.5~2.0 g/ton and 225~300 g per day of gold is getting discarded. It is urgent to develop a technology to recover and reutilize Au. In the present study, flotation tests were carried out to recovery gold for the tailings. Test results show that products with gold grade 21.31 g/ton(Au grade) and 62.73% (Au recovery) were obtained under the optimal conditions including KAX addition rate 97.2 g/ton, frother AF 65 (0.248 l/ton) and depressant sodium silicate (4 kg/ton), it's possible to recover one of the most valuable metal Au, by re-feeding to rougher flotation.

• Resources Recycling
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• v.6 no.3
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• pp.36-40
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• 1997

A series of processes has been developed to recover the gold from electronic scrap containing about 200~600 ppm Au. First, mechanical beneficiation including shredding, crushing and screening was employed. Results showed that 99 percent of gold component leaves in the fraction of under 1mm of crushed scrap and its concentration was enriched to about 800 ppm without incineration. The crushed scrap was leached in 50% aqua regia solution and gold was completely dissolved at $60^{\circ}C$ withing 2 hours. Other valuable metals such as silver, copper, nickel and iron were also dissolved. The resulting solution was boiled to remove nitrous compounds in the leachate. Finally, a newly designed electrolyzer was tested to recover the gold metal. More than 99% of gold and silver were recovered within an hour by electrowinning process.

• Resources Recycling
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• v.8 no.3
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• pp.37-42
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• 1999

Ths sludy was canied out to recover gold and sllics from abandoned gold mine talings with about 4.5 ghonAu and 84.88 wt% SOz. Tl~bee nef~cialiop~ro~c esses including crushing, screening, magnelic and gravity (humprey sp~rals,h aking table) separation \ulcornervex employed. Results were Feasible to rccovn h e gold concentrates (307.1 gltoilon .4u . 0.60 wr%, 97.7 giton Au : 0.27 wl%, 15.3 &/ton Au . 5.23 wt%, 21.2 g/ton Au : 2.42 wl%) and silica (96.40 wi% SiO\ulcorner yield 60 65 ~ 1 % )

• Resources Recycling
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• v.26 no.1
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• pp.51-58
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• 2017

The present study to develop a process for extracting nitric acid and gold from aqua regia leach solution using TBP(tributyl phosphate) was conducted. The pure aqua regia was used to investigate the extractive behavior of nitric acid depending on the concentration of extractant, concentration ratio of nitric and hydrochloric acid. The extraction rate of nitric acid and gold from the gold bearing aqua regia was also examined. The theoretical extraction number was verified by counter current using the number of operations and the phase ratio obtained from McCabe-Thiele diagram. Stripping experiments were carried out for continuous recovery of nitric acid and gold in loaded organic. Considering the effect of extraction acid and gold, the simulation showed that greater than 99.9% extraction of $103.0mg{\cdot}L^{-1}$ gold and 98.0% of $151.2g{\cdot}L^{-1}$ nitric acid could be attained in a two and three-stage counter-current extraction at an O/A phase ratio of 1:0.85. Distilled water and sodium thiosulfate were used as the nitric acid and gold stripping solution. The stripping rates were 99.5% and 92.0%, respectively. The study revealed that the recovery of nitric acid and gold from gold bearing aqua regia was a plausible approach through simultaneous extraction and continuous stripping of nitric acid and gold.

• Resources Recycling
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• v.29 no.2
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• pp.3-7
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• 2020

Recently, the gold leaching technologies draw much interest to recover gold from low grade ores. Current leaching processes mostly use cyanide as the leaching agent, due to its high leaching efficiencies and cost-effectiveness. However, use of cyanide is severely problematic, because of toxicity and thereby environmental risks, and requires strict regulations and environmental management. Especially, this issue becomes further apparent when cyanide should be applied for dump or heap leaching for low cost gold recovery along with recent trends. To resolve this issue, the alternative leaching processes using thiosulfate or halogen compounds, instead of cyanide, have been studied and developed but there have been lots of difficulties toward commercialization, and therefore further research should be conducted. The commercialization of dump or heap bioleaching technologies should be urgently required for effective direct biogenic gold recovery from low grade ores or tailings without use of cyanide.

• Journal of the Mineralogical Society of Korea
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• v.29 no.3
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• pp.113-122
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• 2016

This study aims to improve the recovery of gold and silver by removing hematite from gold ore of an oxidation zone with ammonia solution. Quartz, hematite and muscovite were present in the oxidation zone, while hematite was hydrogenous. As a result of performing an ammonia leaching test on variables, it is found that the maximum Fe leaching parameter was $-45{\mu}m$ particle size, 1.0 M sulfuric acid concentration, 5.0 g/l ammonium sulfate concentration and 2.0 M hydrogen peroxide concentration. It is also confirmed that goethite was precipitated and formed from that ammonia elution. As the amount of Fe-removal was increased in a solid-residue, the recovery of Au and Ag were increased, too.

• Analytical Science and Technology
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• v.8 no.3
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• pp.391-396
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• 1995

A rapid preconcentration method based on solvent extraction is described for the determination of gold by flame atomic absorption spectrophotometry. Trace amounts of gold was extracted as a new chelating agent, 3-thiophenaldehyde-4-phenyl-3-thiosemicarbazone from pH 4.0 in diisobutyl ketone. The method is simple, fast, free from the effect of many interfering ions and has a high sensitivity and a good precision. Gold is quantitatively separated and concentrated from the elements in standard sample, and the value of the recovery was 91.7 and 108.3% by the proposed method.

• Conservation Science in Museum
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• v.14
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• pp.61-67
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• 2013

Lacquerware of Goryeo period was variously developed from the early 10th century to the 14th century and became lacquerware inlaid with mother-of-pearl which shows creativity with splendid heyday. For characteristics, splendid and close mother-of-pearl. Characteristic of decoration method is to use gold painting method, Tortoise shell and metal line. Drawing is done with gold dust and gold painting method decorating lacquerware are very splendid from an artistic and decorative aspect, but gold painting is easily lost. So, it's currently difficult to find in relics succeeded. Therefore, there are domestically insufficient studies on gold painting method in Goryeo period, so this researcher intended to observe gold painting of lacquerware excavated in Goryeo period through the microscope, investigate characteristics, mixture, etc. of gold dust and provide data of studies on the recovery of ancient technology. As the result, gold dust particle has various shapes such as irregular square, polygon and triangle under the size from 2 ㎛ to 20 ㎛. The end of gold dust is rolled and overlapped and irregular particle seems to be similar to the shape of crumpled paper. This research showed that gold dust used in gold painting of Goryeo period had used gold dust made by grinding gold leaf to gold painting.