• Resources Recycling
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• v.10 no.3
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• pp.29-36
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• 2001

Cyclic voltammetry has been applied in the basic studies for the treatment and recovery of heavy metal component contained in wastewater by electrochemical reduction. The electrochemical behaviors of zinc ion for zinc metal electrode and carbon elec-trode were characterized by voltammograms and it was showed that zinc ions were reduced to metallic form below -0.76 V vs SHE. The change in the features of crystalline form of metallic zinc upon oxidation and reduction reaction was observed by X-ray diffraction method and the Am analysis verified that zinc ions were reduced to metal on copper plate. The results of this study were regarded to be important and meaningful in the treatment of heavy metal containing wastewater and, as a result, in the obtainment of metallic product by electrochemical method.

• Corrosion Science and Technology
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• v.10 no.2
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• pp.43-46
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• 2011

Zinc consumption in a continuous galvanizing line is one of the highest operating cost items in the facility and minimizing zinc waste is a key economic objective for any operation. One of the primary sources of excessive loss of zinc is through the formation of top dross and skimmings in the coating pot. It has been reported that the top skimmings, manually removed from the bath, typically consist of more than 80% metallic zinc with the remainder being entrained dross particles ($Fe_2Al_5$) along with some oxides. Depending on the drossing practices and bath management, the composition of the removed top skimmings may contain up to 2 wt% aluminum and 1 wt% iron. On-going research efforts have been aimed at in-house recovery of the metallic zinc from the discarded top skimmings prior to selling to zinc recycling brokers. However, attempting to recover the zinc entrapped in the skimmings is difficult due to the complex nature of the intermetallic dross particles and the quality and volume of the recycled zinc is highly susceptible to fluctuations in processing parameters. As such, an efficient method to extract metallic zinc from top skimmings has been optimized through the use of a specialized thermo-mechanical process enabling a continuous galvanizing facility to conserve zinc usage on-site. Also, through this work, it has been identified that filtration of discrete dross particles has been proven effective at maintaining the cleanliness of the zinc. Future efforts may progress towards expanded utilization of filters in continuous galvanizing.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.11a
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• pp.10-10
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• 2000

Mechanical alloying (MA) is a powder metallurgy processing technique involving cold welding, fracturing, and rewelding of powder particles in a high-energy ball mill. This has now become an established commercial technique in producing oxide dispersion strengthened (ODS) nickel- and iron-based materials. The technique of MA is also capable of synthesizing non-equilibrium phases such as supersaturated solid solutions, metastable crystalline and quasicrystalline intermetallic phases, nanostructures, and amorphous alloys. In this respect, the capabilities of MA are similar to those of another important non-equilibrium processing technique, viz, rapid quenching of metallic melts. however, the science of MA is being investigated only during the past ten years or so. The technique of mechanochemistry, on the other hand, has had a long history and the materials produced this way have found a number of technological applications, e.g., in areas such as hydrogen storage materials, heaters, gas absorber, fertilizers. catalysts, cosmetics, and waste management. The present talk will concentrate on the basic mechanisms of formation of non-equilibrium phases by the technique of MA and these aspects will be compared with those of rapid quenching of metallic melts. Additionally, the variety of technological applications of mechanically alloyed products will be highlighted.

• Resources Recycling
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• v.5 no.3
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• pp.31-36
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• 1996

The metallic copper was recovered from sludge of the copper electro-plating plant by pyrometallurgical process. The reducing agent was Pyrolysized from waste tires and the flux was a mixture $Na_2CO_3$, $NaB_4O_7$, and glass. The green sludge contained 87.5% moisture and 12.5% solid with 56.5% Cu and 1.59% Fe. The sludge dried at $100^{\circ}C$ was analyized to be $Cu_4SO_4(OH)_6{\cdot}2H_2O$ and CuO by XRD analysis. The former was 84% and the latter 16%, However, the calcined sludge at $500^{\circ}C$ was 49% $Cu_2O(SO_4)$ and 51% CuO. The sludge could by smelted at $1100^{\circ}C$ for two hours with 6 to 8 moles carbon with respect to copper to produce metallic copper (>90%) with recovery of 9% above.

• Resources Recycling
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• v.25 no.4
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• pp.42-48
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• 2016

A research for the recovery of the metal with high purity from the waste tin plating solution was carried out. First, tin plating waste solution was tested to remove the organic substances and metallic impurities such as Fe, Zn, Na etc. using ion exchange resin having iminodiacetic functional groups (Lewatit TP 207). Second, the tin solution was purified to obtain the high purity tin solution using ion exchange resin having ethylhexyl-phosphate functional groups (Lewatit VPOC 1026). Finally, 99.98% of the high purity of tin metal can be recovered from the purified solution by cyclone type electrowinning method.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.278-283
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• 2005

Cement and paraffin waste form were prepared with a acid extraction method for the analysis of radionuclides generated from nuclear power plants. The acid extraction method was carried out with $HNO_3-HCl$ acid. At first, we compared the method with the microwave acid digestion method using SRM. The solutions of decomposed SRM were then analyzed by AAS and ICP-AES. The acid extraction method had shown good results as microwave acid digestion method. This method provided recovery values greater than $80\%$ for metallic elements.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.59-61
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• 2005

In Korea, hundreds of abandoned and closed coal and metallic mines are present in the steep mountain valleys due to the depression of the mining industry since the late 1980s. From these mines, enormous amounts of coal waste were dumped on the slopes, which causes sedimentation and acid mine drainage (AMD) to be discharged directly into streams causing detrimental effects on soil and water environments. A limestone slurry by-product (lime cake) is produced from the Solvay process in manufacturing soda ash. It has very fine particles, low hydraulic conductivities ($10^{-8}{\sim}10^{-9}cm/sec$), high pH, high EC due to the presence of CaO, MgO and $CaCl_2$ as major components, and traces of heavy metals. Due to these properties, it has potential to be used as a neutralizer for acid-producing materials. A field plot experiment was used to test the application of lime cake for reclaiming coal wastes. Each plot was 20 x 5 m (L x W) in size on a 56% slope. Treatments included a control (waste only), calcite ($CaCO_3$), and lime cake. The lime requirement (LR) for the coal waste to pH 7.0 was determined and treatments consisted of adding 100%, 50%, and 25% of the LR. The lime cake and calcite were also applied in either a layer between the coal waste and topsoil or mixed into the topsoil and coal waste. Each plot was hydroseeded with grasses and planted with trees. In each plot, surface runoff and subsurface water were collected. The lime cake treatments increased the pH of coal waste from 3.5 to 6, and neutralized the pH of the runoff and leachate of the coal waste from 4.3 to 6.7.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.4
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• pp.383-398
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• 2022

The electrochemical behavior was investigated during the electrolysis of nickel oxide in LiCl-Li₂O salt mixture at 650℃ by changing several components. The focus of this work is to improve anode design and shroud design to increase current densities. The tested components were ceramic anode shroud porosity, porosity size, anode geometry, anode material, and metallic porous anode shroud. The goal of these experiments was to optimize and improve the reduction process. The highest contributors to higher current densities were anode shroud porosity and anode geometry.

• Resources Recycling
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• v.13 no.3
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• pp.50-57
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• 2004

Waste aluminum dross is a major waste in the aluminum scrap smelters and its components are mostly alumina and remained metallic aluminum. In the process to extract the remained aluminum from the waste dross by leaching with sodium hydroxide solution, residue is generated and its main component is alumina. This residue could be recycled into ceramic materials such as alumina castable refractories by going through a series of treatments such as washing, drying and roasting. In this study, a pilot plant was constructed and tested to demonstrate the developed technology. One thousand tons of waste aluminum dross could be processed, and about seven hundred tons of ceramic materials produced in the demonstration line. From the test run of the pilot plant, although it was confirmed that the developed technology could be applied to commercialization, several technical improvements were found to be necessary for reducing impurities such as Na, Fe and for reforming drying equipment.

• Resources Recycling
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• v.14 no.4 s.66
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• pp.41-46
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• 2005

Waste aluminum dross is a major waste in the aluminum scrap smelters and its major components are alumina and metallic aluminum. In this study, waste aluminum dross was leached with sodium hydroxide solution to extract the remained aluminum into the solution, and aluminum hydroxide was recovered from the leached solution. The dross residue generated at the leaching step was recycled into alumina base ceramic materials through a series of treatments such as washing, drying and roasting. Also, a pilot plant was constructed and tested to demonstrate the developed technology. Four tons of waste aluminum dross could be processed per day. From the test run of the pilot plant, it was confirmed that the developed technology could be applied to commercialization.