• Journal of the Mineralogical Society of Korea
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• v.27 no.4
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• pp.207-222
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• 2014

In order to recover the metallic copper powder from the mine-waste rock, heap bioleaching, Fe removal and electrowinning experiments were carried out. The results of heap leaching with the mine-waste rock sample containing 0.034% Cu showed that, the leaching rate of Cu were 61% and 62% in the bacteria leaching and sulfuric acid leaching solution, respectively. Sodium hydroxide (NaOH), hydrogen peroxide ($H_2O_2$) and calcium hydroxide ($Ca(OH)_2$) were applied to effectively remov Fe from the heap leaching solution, and then $H_2O_2$ was selected for the most effective removing Fe agent. In order to prepare the electrolytic solution, $H_2O_2$ were again treated in the heap leaching, and Fe removal rates were 99% and 60%, whereas Cu removal rates were 5% and 7% in the bacteria and sulfuric acid leaching solutions, respectively. After electrowinning was examined in these leaching solution, the recovery rates of Cu were obtained 98% in bacteria and obtained 76% in the sulfuric leaching solution. The dendritic form of metallic copper powder was recovered in both leaching solutions.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.1
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• pp.41-51
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• 2020

The purpose of this study was to investigate the possibility of eco-friendly/efficient recovery of valuable resources, such as Au from mine tailings, which are environmental pollutants in the Mongolian mine sector. For this purpose, this study selected 4 place of mine tailings of the Mongolian mines sector and carried out mineralogy evaluation of the valuable resources in the tailings. In this study, flotation was performed to separate and concentrate valuable resources in the tailings. Microwave nitric acid leaching was used to leach the valuable resources contained in the sample and to improve the Au grade. Chloride leaching attempted to leach Au from the leaching residues. XRD analysis of the tailings samples showed that most of the samples consisted of silicate minerals. As a result of confirming the content of the element through XRF analysis, the SiO₂ content was very high, the Fe₂O₃ content was 2.32-4.23%, and the content of PbO, CuO and ZnO components were all within 2%. As a result of flotation for the tailings samples, the recovery of Au was the highest in Bayanairag sample (95.38%). As a result of microwave nitric solution experiment on Au concentrate sample obtained by flotation, the content of Au in the microwave nitrate leaching residue increased by 12.15% from 192.72 g/ton to 216.14g/ton in Khamo sample, the highest increase was 57.58% in Bayanairag sample. TCLP tests on tailings generated after flotation showed dissolution characteristics within EPA. Chloride leaching test was performed to recover Au from solid residues. The leaching rate was 87.43-89.35% within 10 minutes. For Khamo sample, 100% Au was leached after 60 minutes of leaching time. Therefore, in order to process the tailings continuously generated in Mongolia, applying the same process as the present study is expected to effectively recover the valuable resources contained in the tailings.

• Food Science of Animal Resources
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• v.20 no.3
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• pp.236-241
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• 2000

본 연구는 한우우소뼈로 만든 용출액의 품질에 대한 과학적인 자료를 제시하고 한우뼈의 부가가치 향상 및 소비 확대를 위하여 추출횟수별에 따른 이화학적, 관능적 및 영양적 특성을 규명하였다. 탁도, 점도 및 콘드리이친황산함량에서 추출횟수가 증가할수록 유의적으로 감소한 반면(P<0.05), 콜라겐 함량에서는 추출회수가 증가할수록 유의적으로 증가하였다(P<0.05). 색도에서 명도는 추출회수가 증가할수록 유의적으로 감소한 반면, 적색도와황색도는 증가하였다(P<0.05) 관능평가에서 추출 회수가 증가할수록 평가가 유의적으로 낮았고 (P<0.05), 총질소, 나트륨, 칼슘 함량 및 칼로리는 추출회수가 증가할수록 2차추출까지 증가하다가 이후 유의적으로 감소하였다. (P<0.05)조직특성에서 추출전 대퇴골의 단면은 골수가 많이 분포하고 있으나 추출회수가 증가할수록 골수가 추출되어 3차 추출이후의 대퇴골 단면에는 골수 성분이 거의 나타나지 않았다. 이상의결과를 종합하여 볼 때 한우우소뼈로 설렁탕을 가정에서 제조시 3차까지 우려내는 것이 적당한 것으로 사료된다.

• 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.

• Food Engineering Progress
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• v.15 no.2
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• pp.143-147
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• 2011

For efficient extraction of protein from defatted rice bran, the 5 ranges of extraction pH (8, 9, 10, 11 and 12) and the 3 ranges of isoelectric precipitation pH (2, 4 and 6) were used. The protein content, browning reaction, the electrophoresis pattern and the recovery yield of soluble protein at each pH range were compared each other. The recovery yield of soluble protein increased in proportion to extraction pH, but at the same time, browning reaction became more conspicuous. The most amount of protein was recovered at the precipitation pH of 4. The SDS-PAGE patterns of the extracted proteins showed no significant correlations between pH and the protein content, but the highly alkaline condition was more advantageous to extract protein less than 35 kDa. In each pH range, the recovery yield of soluble protein averagely reached 32.5% on the basis of extraction. In result, it was found that combination of extraction pH 10 and precipitation pH 4, which resulted in 37.65% of recovery yield and low level of browning reaction, was the optimum condition for the extraction of protein from defatted rice bran.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.11
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• pp.627-634
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• 2016

We investigated the characteristics of heavy metal desorption and recovery from carbon foam after plating wastewater treatment. The heavy metal desorption depends on solution chemistry because desorption occurred in HCl and $H_2SO_4 $ solution but did not occur in distilled water. Heavy metal desorption efficiency was increased using ultrasonication with desorption solution. The higher ultrasonic power and the longer reaction time improve efficiency. The copper plating rinse solution was treated reliably by carbon foam adsorbent during 200 bed volume. The adsorbed copper was dissolved using desorption solution and recovered by DC power supply. After copper recovery, the reuse efficiency of desorption solution was 84.2%.

• Korean Journal of Food Science and Technology
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• v.17 no.4
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• pp.265-270
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• 1985

The saponin yield and its compositional changes of red ginseng extract (RG-EXT) was investigated during extraction at various temperature for 5 times of 8 hours. The higher temperature resulted an increase in solids yield while the total saponin recovered was decreased, particularly at $100^{\circ}C$. A relatively lower thermal stability was found for protopanaxadiol saponin, one of the saponin fractions, than protopanaxatriol saponin. The compositional ratio of saponin at ginsenoside level was little affected by extraction time. The yields data showed that more than 94% of total saponin was recovered by 3$\sim$4 times of 8 hours extraction. Extraction at $80^{\circ}C$ for 4 times of 8 hours were suggested for preparation of RG-EXT from the result of this work.

• 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.

• Journal of the Korean earth science society
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• v.35 no.4
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• pp.259-266
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• 2014

This study was carried out to find an environmental friendly and effective way to leach Au and Ag from scrap of Printed Circuit Boards (PCBs) using sodium-hypochlorite solution. In an EDS analysis, valuable metals such as Cu, Sn, Sb, Al, Ni, Pb and Au were all found in PCBs. The highest leaching rates obtained were 1% of pulp density with a chlorine:hypochlorite of 2:1 and a concentration of NaCl at 2M. The highest Au recovery was observed with the addition of sodium metabisulfite to make a 3M solution. It is confirmed that the leaching agent (chlorine-hypochlorite) could effectively leach Au and Ag from Printed Circuit Boards (scrap parts) and the additive reagent sodium metabisulfite could easily precipitate Au from the chlorine-hypochlorite solution.

• Food Engineering Progress
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• v.13 no.4
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• pp.262-268
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• 2009

A dark brownish pigment in the crude polysaccharide from Auricularia auricula was adsorbed by activated charcoal. The leaching of the pigment adsorbed on activated charcoal and regeneration of activated charcoal used was investigated with eight kinds of solvents. The highest leaching capacity was obtained with the alkaline solution (KOH). The optimum volume of 1 M KOH solution per activated carbon was 45 mL/g, and the treatment for 10 min during single stage leaching was sufficient to achieve the leaching equilibrium. Second-order kinetic model provided the best fitting for the pigment leaching. The pigment leaching capacity of 88.9% was obtained by seven times of treatment with 1 M KOH solution at 25$^{\circ}C$, while at 95$^{\circ}C$, leaching capacity of 82.6% was achieved with single stage alone showing the significant increase of leaching capacity with increasing temperature. The regenerated activated charcoal was nearly as effective as fresh activated charcoal in pigment adsorption of crude polysaccharide from Auricularia auricula.