• Journal of the Korean GEO-environmental Society
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• v.16 no.3
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• pp.35-39
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• 2015

Continuous adsorption and recovery characteristics for gold and lead-cyanide complexes in industrial wastewater were investigated by the Dowex 21K XLT resin. The Dowex 21K XLT resin could continuously remove over 95% for gold-cyanide complex until 520 bed volumes at the 0.5 mL/min of influent flow rate, however, could not remove lead-cyanide complex at all. The 96% of gold-cyanide complex adsorbed onto Dowex 21K XLT resin could be recovered by mixed solvent with HCl and acetone (7:3 ratio) within 8 bed volumes. Also, the bed volume for gold-cyanide complex using secondly reused Dowex 21K XLT resin was maintained as the 490, therefore, continuous process using Dowex 21K XLT resin can be sufficiently applied to the industrial wastewater containing gold ions.

• 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.

• Resources Recycling
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• v.24 no.4
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• pp.61-66
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• 2015

Cyanidation has been used worldwide to recover gold from primary ore or concentrate. The use of cyanide is however becoming an emerging issue because of the toxic residue and wastewater made from the process. The cyanide-containing wastewater should be treated properly, obeying the environmental standard and regulations. In the present article, the domestic and international uses, regulations, and treatment technologies of cyanide in gold mining were investigated as a feasibility study to develop a cyanide treatment process as well as the cyanidation process. A biological cyanide treatment process to develop a zeroemission gold recovery and wastewater treatment process was also briefly introduced.

• 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.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.19 no.3
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• pp.9-15
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• 2010

Domestic gold mine tailings, generally, contain a lot of non-metallic silica and clay minerals. These minerals can be separated from the tailings by various physical separation methods and used as raw materials for cements and ceramic products. In these physical separation procedures, metallic complex sulfides, in which Au and metallic constituents such as Pb, As and Fe were concentrated, were obtained as a by-product. These metallic constituents should be removed or separated from the by-product to extract Au efficiently. In this work, removal and separation processes of Pb, As, and Fe from the by-product were investigated. Pb was removed to under 3% by using alkaline oxidative leaching at the leaching condition of $120^{\circ}C$, 2M NaOH, 100psi $Po_2$, 250r.p.m., 4 wt.% solid and 30 min. leaching time. The leached residue was roasted and separated magnetically to obtain a non-magnetic product contained <0.2% As, <3% Fe and high concentrated Au more than 8,000 ppm.

• Economic and Environmental Geology
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• v.53 no.2
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• pp.183-196
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• 2020

This study aimed to recover native gold from the concentrate using microwave-nitric acid leaching and magnetic/hydro separation experiments. The insoluble-residue was filtered from leaching solution through microwave-nitric acid leaching experiment. As a result of the atomic absorption spectrometer(AAS) analysis of the filtered leaching solution, it was discovered that Au content was not eluted at all and it was observed from the back scattered electron(BSE) image that native gold was liberated in the insoluble-residue. When magnetic/hydro separation experiments were applied for the insoluble-residue, magnetic and non magnetic minerals were separtated from insoluble-residue. Magnetite was recovered from the magnetic minerals and as a result of applying the hydro separation experiment again for the non-magnetic mineral, native gold was recovered. The native gold was identified through the X-ray diffraction(XRD) analysis and BSE image.

• Economic and Environmental Geology
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• v.52 no.6
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• pp.595-604
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• 2019

The purpose of this study was simply to obtain gold through a microwave-nitric acid experiment of invisible gold concentrate with the use of filter paper. For the purpose, this study conducted a microwave-nitric acid leaching experiment and examined nitric acid concentration. As a result of the experiment, this study discovered that Fe, Te and Ag were completely leached in the leaching solution whereas Au was not determined in all of the nitric acid conditions. The leaching solution was filtered with three filter papers and then these filter papers were analyzed with SEM/EDS. As a result of the EDS analysis, Au was detected in all of the surface and cross-section of the 1st, 2nd and 3rd filter papers. As the three filter papers containing solid-residue were analysed in the lead-fire assay, gold particles were found in all of the nitric acid conditions. In the lead-fire assay, maximum gold(452.50g/t) was recovered when nitric acid concentration was 6M and microwave leaching time was 12mins.

• Economic and Environmental Geology
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• v.46 no.6
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• pp.477-484
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• 2013

In order to recover gold from iron-hydroxide in acid mine drainage, a lead-fire assay has been used. Acid mine drainage is generated from mining waste rocks, and iron-hydroxide precipitates from acid mine drainage, which severely contaminates the area surrounding the mine. Iron-hydroxide samples contain on average 520.29 mg/kg of Fe, 4,414.62 mg/kg sulfur, and 16.19 mg/kg Au. In an XRD analysis, quartz and goethite were observed along with the iron-hydroxide. Using a lead-fire assay, the recovery of pure gold was on average 0.174 g/ton from the iron-hydroxide, whereas the gold not recovered in the process was on average 1.37 mg/kg. This unrecovered gold was lost to the glass slag due to the galena and lead formation. The galena and lead in the glass slag was identified through XRD.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.26-40
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• 2000