• Resources Recycling
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• v.28 no.1
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• pp.23-31
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• 2019

Cementation is one of economical and efficient recycling method precipitating the metal ion in solution by adding another active metal. In this study for optimizing cadmium recovery efficiency, it was performed as a function of the effect of pH, temperature, particle size, and input amount of zinc in 0.1 M $CdSO_4$ solution and Ni-Cd battery leaching solutions, respectively. The particle size of zinc and temperature were key factors for Cd cementation and it was confirmed that the input amount of 2.6 of Zn/Cd ratio using granular-type zinc was optimal condition for selective Cd recovery efficiency at $25^{\circ}C$.

• Resources Recycling
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• v.2 no.4
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• pp.23-26
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• 1993

This work is carried out to develop the recovery process of vanadium as vanadium pentoxide and nickel as nickel sulphate from the leaching solution of heavy oil fly ash. First, sodium chlorate solution was added to the leaching solution to oxidize vanadium ions. With adjusting pH of the solution and heating, vanadium ions(V) is hydrated and precipitated as red cake of $V_2O_5$ from the solution. After recovering vanadium, nickel is recovered as ammonium nickel sulfate with crystallization process. From this nickel salt, nickel sulfate which meets the specifications for the electroplating industry can be produced economically. More than 85% of vana-dium and nickel in the fly ash are recovered in this process.

• Resources Recycling
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• v.6 no.3
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• pp.41-45
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• 1997

The recovery of tellurium from Te-cement obtained during the processing of copper anode slimes was carried out by a series of hydrometallurgical processes, i.E. leaching Te-cement in NaOH solution, precipitation of impurities with the addition of ${Na}_{2}S$ followed by direct electrowinning of tellurium in NaOH solution. The optimum conditions for each process were determined and discussed in terms of various parameters associated with each step to maximize the recovery and purity of tellurium. The final purity of tellurium from electrownning in alkaline solution was found to be more than 99.9%.

• Journal of Electrochemical Science and Technology
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• v.13 no.2
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• pp.186-198
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• 2022

Heavy metals recovery from Printed Circuit Boards industrial wastewater is crucial because of its cost effectiveness and environmental friendliness. In this study, a copper recovery route combining the sequential processes of acid leaching and LIX 984N extracting with an electrowinning technique from Printed Circuit Boards production's sludge was performed. The used residual sludge was originated from Hanoi Urban Environment One Member Limited Company (URENCO). The extracted solution from the printed circuit boards waste sludge containing a high copper concentration of 19.2 g/L and a small amount of iron (0.575 ppm) was used as electrolyte for the subsequent electrolysis process. By using a simulation model for multi-step current electrolysis, the reasonable current densities for an electrolysis time interval of 30 minutes were determined, to optimize the specific consumption energy for the copper recovery. The mathematical simulation model was built to calculate the important parameters of this process.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.195-203
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• 2012

Recycling method of waste LCD glass is the essential process for developing the total recycling process of LCD pannel. Pulverizing of LCD glass, determination of proper carbonacious foaming agent, the properties of residue from the recovery of valuable materials through an acid leaching process and the feasibility for the foaming of the residue obtained from leaching for indium and tin recovery were investigated for the developing of recycling method of waste LCD glass as industrial feed materials, such as heat insulation materials, sound absorbing materials, carrier of water treatment. Waste LCD glass could be pulverized finely for foaming process. Natural graphite was proper agent for foaming of the residue and the foaming technology of LCD glass would be effective recycling alternatives.

• 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.

• Journal of the Mineralogical Society of Korea
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• v.27 no.2
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• pp.73-83
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• 2014

In order to investigate selective phase transformations and to determine the maximum Au leaching factors from microwave treated Au-bearing complex sulfides, a microscope, SEM-EDS analysis, and thiocyanate leaching tests were performed. When the Au-bearing complex sulfides were exposed to microwave heating, increasing the microwave exposure time increased temperature and decreased weight. Arsenopyrite was first selectively transformed to hematite, which formed a concentric rim structure. In this hematite, oxygen and carbon was detected and always showed high iron content and low arsenic content due to arcing and oxidation from microwave heating. The results of the leaching test using microwave treated sample showed that the maximum Au leaching parameters was reached with 0.5 g concentration thiocyanate, 2.0 M hydrochloric acid, 0.3 M copper sulfate and leaching temperature at$60^{\circ}C$. Under the maximum Au leaching conditions, 59% to 96.69% of Au was leached from the microwave treated samples, whereas only 24.53% to 92% of the Au was leached from the untreated samples.

• Resources Recycling
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• v.27 no.4
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• pp.57-64
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• 2018

Water leaching of tungsten(W) and vanadium(V) was researched from their oxides through mechanochemical (MC) reaction with alkali compounds. Intensive grinding for the mixture of tungsten/vanadium oxide and alkali compounds (NaOH, $Na2CO_3$) was carried out with change of their mixing ratios and grinding duration. Water soluble compounds, $Na_2WO_4$ and $NaVO_3$, were synthesized through MC reaction and their solubilities increased in proportion to the mixing ratio of sodium compound and grinding times. Whereas vanadium leachability was less affected by the mixting ratio and grinding times. The leachabilities of 99.0% were accomplished by a short period of MC treatment, W (30 min.) and V (5 min.). This process enable us to extract W and V from their oxides via a water leaching, and can be applied to the selective recovery of W and V from $DeNO_x$ spent catalysts.

• Resources Recycling
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• v.23 no.1
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• pp.64-69
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• 2014

For the recovery of Co and Cu, bioleaching behavior of Co, Cu, Fe, Mg, Al by Aspergillus niger culture from the molasses growth medium was investigated. Series of leaching tests have been conducted by varying Aspergillus niger's type, molasses concentration in the growth medium, pulp density and reaction time. The results showed that increase of the molasses concentration in the growth medium from 1% to 4% increased the leaching percentage of Co and Cu and the optimal molesses concentration was found to be 4% in the growth medium. Maxinum 90% of Co and 70% of Cu were dissolved from the leaching test at the 10 g/L pulp density, 4 % of molasses concentration in the growth medium after 21 days by Aspergillus niger KCTC 6985. But in case of using Aspergillus niger KCTC 6144, the maxium leaching percentage of Co and Cu was reached 90% respectively at a pulp density 5 g/L and 4% of molasses concentration.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.3
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• pp.296-302
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• 2007

This study was conducted to evaluate the effect of slow release fertilizers (SRF), crotonylidene diurea (CDU) and latex coated urea (LCU), on nitrogen (N) use efficiency (NUE) and nitrate-N leaching in a silty clay loam soil under polyethylene film mulching (PFM) for sesame cultivation. In PFM plot, concentrations of $NO_3-N$ and $NH_4-N$ in SRF applied soils were less than that in the urea plot during the whole growing period. However, $NO_3-N$ and $NH_4-N$ in all the non-mulched plots (NM) were not significantly different. Urea-N in soil treated with SRF was higher than urea plot until 50 days after application and was comparable in all the treatments after 50 days. $NO_3-N$ concentrations in leached solution in 21 days after urea fertilization in PFM and NM were 26 mg $L^{-1}$ and 83 mg $L^{-1}$, respectively. However, $NO_3-N$ in leached solution at applied CDU and LCU was less than that of urea similar to nitrate concentration in soil. $NO_3-N$ in leached solution in applied CDU and LCU in 44 days after application was about 25% lower than that urea plot and PFM, while the $NO_3-N$ concentration of CDU and LCU treatment in NM did not changed. Application of SRF increased the yield of sesame and N recovery compared to urea and there was a little difference between SRF and N levels. In conclusion, application of 80% N level with SRF increased N recovery and reduced nitrate leaching without reduction of yields compared with urea application.