• Journal of the Korea Organic Resources Recycling Association
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• v.27 no.2
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• pp.5-12
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• 2019

The study is carried out to survey the proper management and to propose an eco - friendly separation system through efficient screening and resource recovery of excavated materials containing waste from various excavating fields such as reconstruction of landfill sites for reuse, reclamation of unsanitary landfill and residential land development of waste dumping sites. The current status and screening process and analytical characteristics of the excavated materials containing waste were reviewed. Through the analysis of the samples such as separated combustibles, recyclable soils and residues collected from the on-site visits we were able to understand the characteristics of separated materials and excavated materials containing waste such as calorific value, elementary composition, TOC, foreign material content and LOI. It has been found that elimination of the moisture of excavations, removal of attached soil from the surfaces of the excavated combustibles and the quantitative supply method of the input devices are the main operating factors as essential factors for the optimal separation of excavated materials containing waste. For efficient management and recycling of excavated materials containing, it is necessary to set criteria of ash content in separated combustibles and criteria organic matter content in separated soils.

• Resources Recycling
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• v.8 no.1
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• pp.18-22
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• 1999

In order to utilize incineration fly ash of industrial wastes as resources, we present the recovery and separation of metals included in the fly ash by leaching with aqueous solution A great quantity of Cu, Pb, and Zn as well as a small amount oftoxic heavy metals are contained in the leach liquor of the fly ash, and the concentration of the ingredients of the fly ash depends on the industrial wastes which are fed into incinerators. In this paper, sequential Ieachiog operations are conducted using $H_2O$, $H_2SO_4$, $(NH_4)_2CO_3$ and NaOH as Icachants. Water soluble copper salt was leached by $H_2O$, Zn and Pb were separated by the NaOH leach liquor, and water insoluble copper was selectively leached as chelate ion with the $(NH_4)_2CO_3$ leach liquor of the third Ieaehant. Results show that the reduction percent of the fly ash in the leaching steps using $H_2O$, $H_2SO_4$, and $(NH_4)_2CO_3$ is 77%, and the other leaching procedures lose the weight of fly ash by above 60%.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.4
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• pp.5-10
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• 2018

In this study, the effect of physico-chemical factors (e.g., pressure, electrolyte, and organic matter) in the gas hydrate deposit on CH4-CO2 replacement process was investigated experimentally. The higher initial pressure during gas injection led the higher reaction rate at the first time, but finally it did not. Electrolytes and organic matter have some effects on reforming process after dissociation of gas hydrate. It is expected that further research using real marine sediments with actual gas hydrate will enable the development of technologies applicable to the characteristics of domestic seabed geology. Ultimately, it is expected that it will be possible to recover and utilize methane as an organic resource through application of domestic gas hydrate deposit in the Ulleung Basin, East Sea.

• Environmental Engineering Research
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• v.19 no.3
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• pp.185-195
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• 2014

Despite the enormous technical and economic efforts to improve environmental conditions, currently about 40% of the global population (or 2 billion people) are still lack access to safe water supply and adequate sanitation facilities. Pollution problems and transmission of water- related diseases will continue to proliferate. The rapid population growth and industrialization will lead to a reduction of arable land, thus exacerbating the food shortage problems and threatening environmental sustainability. Natural systems in this context are a transdisciplinary approach which employs the activities of microbes, soil and/or plants in waste stabilisation and resource recovery without the aid of mechanical or energy-intensive equipments. Examples of these natural systems are: waste stabilisation ponds, aquatic weed ponds, constructed wetlands and land treatment processes. Although they require relatively large land areas, the natural systems could achieve a high degree of waste stabilisation and at the same time, yield potentials for waste recycling through the production of algal protein, fish, crops, and plant biomass. Because of the complex interactions occurring in the natural systems, the existing design procedures are based mainly on empirical or field experience approaches. An integrated kinetic model encompassing the activities of both suspended and biofilm bacteria and some important engineering parameters has been developed which could predict the organic matter degradation in the natural systems satisfactorily.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.6
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• pp.215-226
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• 2015

This study introduced food waste into re-vegetation base materials for surface loss recovery of carry-away highway cut slope. The object of this study is to derive the mixing ratio of food waste by conducting a test installation, monitoring, analysis and evaluation for recovery of carry-away highway cut slope. The following items were investigated and analyzed each experimental zone to draw mixing ratio of re-vegetation base materials and food waste : the physical and chemical properties of the vegetation base materials, soil-hardness, soil-humidity, left out and the collapsed point, established number of trees, species richness of grass species and tree species, coverage, pest status, and invasion of disturbance species. The re-vegetation method was evaluated by each experiment zone which has different mixing ratio. As a result, experiment zone A was rated 45 points out of 60 rating points as the best re-vegetation method. However, this study result has been derived from one construction and short-term monitoring. In order to derive the suitable and dependable mixing ratio, conducting an objective re-vegetation method evaluation and long-term experiment and monitoring is required.

• Resources Recycling
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• v.28 no.3
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• pp.26-34
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• 2019

Due to the increasing demand of rare earth magnet for various application, it is predicted that the amount of waste rare earth magnet will increase sharply. The process of waste rare earth magnet recycling is mainly consisted of leaching and separation of rare earth element contained in the magnet. However, there is no study on the breakage characteristics of the waste rare earth magnet for production of magnet powder. Therefore, in this study, effective crushing/grinding process and breakage characteristics were investigated for waste rare earth magnet. In the case of jaw crusher, the particle size of magnet was effectively reduced without rapid oxidation. In ball mill grinding test, it was found that the grinding process was not performed properly at the early stage of grinding. Moreover, waste rare earth magnet showed very low specific rate of breakage(S) and high fraction of fine particle breakage distribution(B) compared to ordinary minerals. These results can be used as a basic data for developing crushing/grinding circuit of waste rare earth magnet.

• Resources Recycling
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• v.32 no.6
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• pp.54-66
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• 2023

Titanium's importance as a mineral resource is increasing, but the Korean industry depends on imports. Ilmenite is the principal titanium ore. However, research and development from raw materials have not been investigated yet in detail. Hence, measures to secure a stable titanium supply chain are urgently needed. Accordingly, through beneficiation technology, we evaluated the possibility of technological application for the efficient recovery of valuable minerals. As a result of the experiments, we confirmed that mineral particles existed as fine particles due to weathering, making recovery through classification difficult. Consequently, applying beneficiation technologies, i.e., specific gravity separation, magnetic separation, and flotation, makes it possible to recover valuable minerals such as hematite and rutile. However, there are limitations in increasing the quality and yield of TiO₂ due to the mineralogical characteristic of the hematite and rutile contained in titanium ore. Hametite is combined with rutile even at fine particles. Therefore, it is essential to develop mineral processing routes, to recover iron, vanadium, and rare earth elements as resources. On that account, we used grinding technology that improves group separation between constituent minerals and magnetic separation technology that utilizes the difference in magnetic sensitivity between fine mineral particles. The development of beneficiation technology that can secure the economic feasibility of valuable materials after reforming iron oxide and titanium oxide components is necessary.

• Resources Recycling
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• v.32 no.1
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• pp.50-59
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• 2023

The amount of dust generated during the dissolution of scrap in an electric arc furnace is approximately 1.5% of the scrap metal input, and it is primarily collected in a bag filter. Electric arc furnace dust primarily consists of zinc and ion. The processing of zinc starts with its conversion into pellet form by the addition of a carbon-based reducing agent(coke, anthracite) and limestone (C/S control). These pellets then undergo reduction, volatilization, and re-oxidation in rotary kiln or RHF reactor to recover crude zinc oxide (60%w/w). Next, iron is discharged from the electric arc furnace dust as a solid called Fe clinker (secondary by-product of the Fe-base). Several methods are then used to treat the Fe clinker, which vary depending on the country, including landfilling and recycling (e.g., subbase course material, aggregate for concrete, Fe-source for cement manufacturing). However, landfilling has several drawbacks, including environmental pollution due to leaching, high landfill costs, and wastage of iron resources. To improve Fe recovery in the clinker, we pulverized it into optimal -sized particles and employed specific gravity and magnetic force selection methods to isolate this metal. A carbon-based reducing agent and a binding material were added to the separated coarse powder (>10㎛) to prepare briquette clinker. A small amount (1-3%w/w) of the briquette clinker was charged with the scrap in an electric arc furnace to evaluate its feasibility as an additives (carbonaceous material, heat-generating material, and Fe source).

• Mineral and Industry
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• v.25
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• pp.1-10
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• 2012

In this present work, the froth flotation of lithium ore from Boam mine located in Wooljin, Kyungbuk has been carried out to produce high-grade lithium concentrate. The sample ore-Lepidolite mainly contained silicate mineral (quartz, muscovite) and calcite. In consequences of the experiment, it has been possible to obtain relatively high-grade lithium while using anionic acid (oleic acid) to remove calcite before the froth flotation for lithium concentrate. Among the amines collectors (Armac-T, Armac-C, Armafloat-18, Armafloat-1597), Armac-T has been relatively effective than another ones. Under the optimum condition (collector : Armac-T 100g/t, frother : AF65 50g/t, depressants : $Na_2SiO_3$ 600g/t and Lactic acid 100g/t, pulp density : 20%, pH 5.5, number of cleaning : 2), it has been obtained relatively high-grade lithium concentrate ($Li_2O$) with recovery of 80.3% and with grade of 4.33%.

• Mineral and Industry
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• v.28
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• pp.1-13
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• 2015

In this study, it was carried out separation process research and development to be able to produce high-grade tungsten concentrate form tungsten taken form Mongolia. In order to reduce treatment cost and increase separation efficiency the jig separation at first was applied for recovering the concentrate. Which reground would make the degree of liberation increase. Which was treated by shaking table to reject the gangue minerals from the first concentrate. Because the heavier product contains not only ferberite but also cassiterite, the product was treated by further dry magnetic separation to obtain the ferberite concentrate. Finally, the high-grade ferberite concentrate of 67.63% $WO_3$ could be obtained with recovery of 86.07% through the separation process developed in this study.