• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.206-209
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• 2001

This study presents the leaching characterization of heavy metals according to changes of pH by ANC test on slag produced in electric arc furnace, bottom ash produced in coal-fired plants and their recycling products. Availability test was performed to assess the fraction of the total concentration that under worst environmental conditions could become available for leaching. TCLP, KLT(Korea Leaching Test) and KLTS(Korea Leaching Test of Soil contamination) were carried out to compare the leaching capacity and to estimate the adequacy of regulatory leaching test. Results from regulatory leaching tests could be misleading because the variable ANC of wastes can lead to very different final leachate pHs. The final pH of the regulatory test is not the ambient pH in the disposal environment, the actual solubilities of contaminants in the field may be entirely different from those predicted by these regulatory tests. Leaching behaviour of by-products was changed by recycling processes, therefore acid neutralization capacity and availability of new products, not leaching concentration by one batch regulatory test, are necessary to determine the method of recycling.

• Computers and Concrete
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• v.1 no.2
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• pp.131-150
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• 2004

We present in this work a coupled phenomenological chemo-mechanical model that represents the degradation of concrete-like materials. The chemical behaviour is described by the nowadays well known simplified calcium leaching approach. And the mechanical damage behaviour is described by a continuum damage model which involves the gradient of the damage quantity. The coupled nonlinear problem at hand is addressed within the context of the finite element method. For the equation governing the calcium dissolution-diffusion part of the problem, special care is taken to treat the highly nonlinear calcium conductivity and solid calcium functions. The algorithmic design is based on a Newton-type iterative scheme where use is made of a recently proposed relaxed linearization procedure. And for the equation governing the damage part of the problem, an augmented Lagrangian formulation is used to take into account the damage irreversibility constraint. Finally, numerical simulations are compared with experimental results on cement paste.

• 연구논문집
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• s.28
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• pp.161-172
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• 1998

In the recycling industry, the recuperation of zinc from Electric Arc Furnace dust by the Waelz process generates important quantities of slag. This slag presents good mechanical properties, and for the most siliceous slag. a high stability which would enable its use by total or partial substitution of certain granulates in civil engineering Our study (within the framwork of a European programme cofunded by the European Commission-DGXII) concerns the physico-chemical and mineralogical characterization and leaching behaviour of several types of Waelz slag. The leaching tests are regulatory tests and specific characterization tests of leaching behaviour. They take into account the influence of several main parameters of the valorization scenarios envisaged for the slag(e.g. pH, Redox potential, chemical nature of the leachant, type of contact-liquid/ solid etc.).

• Resources Recycling
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• v.13 no.4
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• pp.32-38
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• 2004

Recently, Orimulsion (a bitumen-in emulsion) has received increasing attention as an alternative fuel. Orimulsion combusion produces an ash rich in V, Ni and Mg which are processed to recover metals. As a basic study to recover V from Orimulsion ash, physico-chemcial properties and leaching behaviours were investigated. Orimulsion ash was fine size grains ($d_{50}$ 5.9 $\mu\textrm{m}$) with 16% V, 4 % Ni and 9% S. Vanadium was easily leached in water because Orimulsion ash was mainly constituted of metal sulfates. However, the increase of leaching temperature decreased the extraction percentage of vanadium because of hydrolysis of V(V) to vanadium pentoxide. The addition of sulfuric acid could increase the leaching percentage vanadium. In case of alkaline leaching for selective recovery of vanadium, the oxidzing agent such as $H_2$$O_2$ is required to improve the leaching per-centage

• Journal of the Korean GEO-environmental Society
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• v.16 no.12
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• pp.37-43
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• 2015

Ground characteristics is important in tunnel structure utilizing the strength of underground. In the case of the fault fracture zone such as weak soil conditions exists in the tunnel section and groundwater leaching occurs at the same time, it happens to occur to excessive displacement or collapse of tunnel frequently. Fault fracture zone is an important factor that determines the direction of displacement and the collapse of the tunnel under construction. Behavior of fault fracture zone is determined depending on the size and orientation of the surface portion of the tunnel. If the groundwater occurs in the face of tunnel, groundwater causes displacement and collapse. And the collapse characteristics of tunnel is a major factor in determining that the time-dependent behavior. It is difficult to accurately predict groundwater leaching from the fault fracture zone in the numerical analysis method and analyze the interaction behavior of groundwater and fault fracture zone. Therefore numerical analysis method has limitations the analysis of ground water in the ground which the fault fracture zone and groundwater occurs at the same time. It is required to comprehensively predict the behavior of tunnel and case studies of tunnel construction. Thus, the location of fault fracture zone is an important factor that determines the direction of displacement and the collapse of the tunnel. In this study, behavior characteristics of the tunnel according to the location of the fault fracture was analyzed.

• Resources Recycling
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• v.24 no.1
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• pp.3-11
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• 2015

Soluble silica generated from acid leaching process is very difficult to filter and deceases the purity of products, and thus becomes one of hot issues in hydrometallurgy. This paper reviewed the dissolution and reactivities of silicates in acid solution, and the methods for treatment of soluble silica. Removal of silica with alkaline pre-treatment, crystallization to $SiO_2$ and precipitation behaviour of silica with coagulation under acid conditions were briefly described.

• Structural Engineering and Mechanics
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• v.40 no.5
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• pp.655-663
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• 2011

Asbestos-cement is a material with valuable strength and durability. It was extensively used for water distribution pipes across the world from the 1950s until the early 1980s. The network of pipes in this case study dates from the 1970s, and after more than 30 to 40 years of service, some pipes have been found to break under common service pressure with no apparent reason. A set of mechanical tests was performed including bending, compression, pressure and crushing tests. Microscopy analysis was also used to understand the material behaviour. Tests showed that there was a clear loss of strength in the pipes and that the safety factor was under the established threshold in most of the specimens. Microscopy results showed morphological damage to the pipes. The loss of strength was attributed to a leaching effect. Leaching damages the cement matrix and reduces the frictional interfacial shear stress.

• Resources Recycling
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• v.17 no.1
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• pp.51-58
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• 2008

Artificial mattes were prepared with adding pyrite or chalcopyrite as sulfur sources with Cu-Ni-Co-Fe alloy. The major phases identified by X-ray diffraction pattern were $(FeSi)_9S_8$, $CuFeS_2$, FeS, $Co_4S_3$, $Ni_3S_2$ and $Cu_2S$ for both mattes, and the matte prepared by adding chalcopyrite showed the higher peak of $Cu_2S$ due to high content of copper. Under optimum conditions, more than 95% copper, 90% nickel and 90% cobalt were extracted into leaching solution and sulfur concentration in the mattes did not much affect the leaching efficiency of the metals. The increase of the amount of pyrite or chalcopyrite added decreased pH in leaching solution and increased the concentration of iron ion dissolved in the leaching solution and the amount of residue.

• The Korean Journal of Pesticide Science
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• v.2 no.2
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• pp.59-67
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• 1998

토양중 침투성 살충제 carbofuran과 제초제 petilachlor의 용탈행적을 구명하기 위하여 물리화학적 성질이 상이한 2종의 논토양으로 충전된 토양 column (내경 5cm ${\times}$ 길이 30cm)에 $^{14}C$-표지 화합물을 각각 처리한 후 벼 (Oryza sativa L.)를 생육시키면서 벼를 심지 않은 경우를 대조구로 하여 8주 동안 주당 95.2 ml씩 용탈시켰다. Carbofuran의 경우 토양 column에서 용탈된 $^{14}C$ 방사능의 양은 벼를 재배하지 않은 토양 A와 B에서 각각 총처리 방사능의 74.8와 92.3%였으며, 벼를 재배한 토양에서는 각각 45.1%와 69.7%였다. 반면에 petilachlor의 경우 벼를 재배한 토양 column에서는 각각 총처리 방사능의 2.4%와 5.0%가 용탈되었으며, 벼를 재배한 경우는 각각 3.1%와 8.2%가 용탈되었다. 토양에 처리한 [$^{14}C$]화합물 모두 벼의 생육유무에 관계없이 양이온치환용량, 유기물 및 점토의 함량이 적은 토양 B에서 $^{14}C$ 방사능의 용탈이 증가되었다. 토양 column중 carbofuran의 이동성은 매우 높은 반면에 petilachlor는 매우 낮았으며, 이는 그들의 토양흡착과 수용성에 기인된 것으로 판단된다.

• Korean Journal of Environmental Agriculture
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• v.12 no.3
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• pp.281-297
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• 1993

Nitrogen is an element required to meet optimal plant growth. However, when it was applied (as chemical fertilizer or animal waste) more than the demand of plant and managed it unreasonably can be accumulated in subsoil and leached from soil system. Nitrogen also can be act as an pollutant to soil and water through water contamination if its concentration exceed the critical level. The concentration and downward movement of nitrate in soil is influenced by cultural practices and soil properties. High level of nitrate nitrogen in drinking water is harzadrous for animal and human health, especially for infants and the restoration of the quality of groundwater is impossible by now. Therefore it is the only way to prevent from leaching of nitrate nitrogen to keep the quality of groundwater as vital water resource. The aims of the presentation of this review paper are to understand the relationship between agricultural practices and the concentration of nitrate nitrogen in groundwater and to suggest further informations for the rational management methods to reduce the leaching of nitrate nitrogen in soil.