• Environmental Engineering Research
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• v.25 no.3
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• pp.345-355
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• 2020

This study has been carried out to evaluate the leaching behavior of Tunisian phosphogypsum (PG) tailings in Skhira city (southern Tunisia). Two PG samples, including old and freshly deposited samples, were characterized in terms of physical, geotechnical, mechanical, chemical and mineralogical properties. Special attention was paid to their leaching behavior when subjected to standard leaching tests. Our results indicated that both samples are mainly composed of more than 31.85% CaO and 31.4% SO3, indicating the predominance of gypsum. This was further confirmed by XRD patterns that revealed the presence of characteristic reflections of gypsum, brushite, quartz and Maladrite. Compressive strength after 90 d exceeded 769 kPa, but still lower than that of natural sand (1,800 kPa). Leaching test was proposed as an appropriate method to determine the released contaminants from PG. The obtained results showed that Fluorine and Phosphorus are the most released elements from PG with 40 and 30%, respectively. The released Se, Cd, and Zn were the only trace elements that exceeded the threshold limits. It seemed that leached element concentrations were independent aging or particle size of the PG. Based on the assessment of leaching behavior, an integrated management approach of the PG deposits was proposed.

• Polymer(Korea)
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• v.29 no.3
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• pp.282-287
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• 2005

A novel ice particle leaching method for fabrication of porous and biodegradable PLGA scaffold has been proposed for the application to tissue engineering. After uniform mixing of poly(L-lactide-co-glycolide) (PLGA) and bovine serum albumin-fluorescein isothiocyanate (FITC-BSA), the FITC-BSA loaded scaffold was fabricated by adding various ratio of ice particle. The release profiles of FITC-BSA were examined using pH 7.4 PBS for 28 days at $37^{circ}$. The release amount was determined by fluorescence intensity by using the fluorescence spectrophotometer and the morphological change of the scaffolds was observed by scanning electron microscope. The release initial burst of BSA containing scaffolds was lower than that of simple dipping scaffolds resulting in constant release aspect. Although the BSA concentration increased. the initial burst was not increased. As a result of this study, it can be suggested that ice particle leaching method for the tissue engineered scaffold miff be very useful and it is possible to impregnate with water soluble factors like cytokine. We suggest that ice particle leaching method may be useful to tissue engineered organ regeneration.

• Economic and Environmental Geology
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• v.39 no.2 s.177
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• pp.181-190
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• 2006

Garnet has been suggested as one of the most promising material for the immobilization of radionuclide in high level waste. But data on its chemical durability are sufficiently available. Accordingly, Gd and Ce garnets were synthesized as imitators for $Pu^{3+}\;and\;Pu^{4+}$ were synthesized, and their leaching rates, the parameters of the chemical durability were measured by changing the conditions. In distilled water, the ranges of leaching rates of Gd and Ce were $1.2{\times}10^{-4}{\sim}4.6{\times}10^{-6}g/m^2/day\;and\;7.5{\times}10^{-5}{\sim}1.8{\times}10^{-7}g/m^2/day$, respectively. A comparison with previous data suggests that the chemical durabilities of garnets synthesized from this study are superior to those of other waste forms. Additional leaching experiments were performed with 0.01M-HCl and 0.01M-NaOH solutions to see Gd and Ce leaching at acidic and alkalinity conditions. In 0.01 H-HCl solution, the ranges of leaching rates of Gd and Ce were $2.5{\times}10^{-1}{\sim}6.9{\times}10^{-3}g/m^2/day\;and\;3.7{\times}10^{-1}{\sim}3.1{\times}10^{-3}g/m^2/day$, respectively, while were $3.1{\times}10^{-4}{\sim}1.3{\times}10^{-6}g/m^2/day\;and\;1.8{\times}10^{-3}{\sim}0g/m^2/day$, respectively in 0.01M-NaOH solution. It is believed that leaching data can be used in understanding chemical durabilities of waste from garnets in acidic and alkaline conditions.

• Korean Journal of Microbiology
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• v.11 no.2
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• pp.69-78
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• 1973

In order to investigate the distribution of an iron-oxidizing bacterium, Ferrobacillus ferrooxidans in Korea, the authors had carried out the chemical and microbiological analysis of mine water. The results obtained were as follows : 1. Ferrobacillus ferrooxidans concerned to leaching was isolated from 10 copper mine water out of 46 sites in Korea. 2. As the results of bacterial oxidation, the contents of sulfuric acid, ferric sulphate and copper in the bacteria-bearing solutions were higher than those in bacteria-free solutions.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.192-199
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• 1999

In order to make the reasonable irrigation planin the reclaimed paddy fields, the estimation of irrigation water requirements by soil textures and water management methods for the normal growth of crops is very important. This study was carried out to determine leaching water requirements before cultivating crops. For the purposes of this study, the physical and chemical properties of soil sampels used in the desalinication experiments were analyzed and change of salinity by supplying water and leaching water were investigated in the experimental field with lysimeters.

• Journal of the Mineralogical Society of Korea
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• v.28 no.1
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• pp.17-28
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• 2015

In order to study the mineralogical and chemical characteristics of copper slag, optical microscopy, SEM/EDS, EPMA, AAS and XRD analyses were carried out. In addition, sulfuric acid leaching experiments were performed to investigate the potential of the slag as a copper resource. It was confirmed that fayalite, chromite, bornite and chalcopyrite were contained in the slag. The slag mainly consisted of acicular fayalite and skeletal lath -euhedral chromite crystals. Also a very large amount of bornite and chalcopyrite grains were contained in the slag. The content of Fe and Cu in the slag was 18.37% and 0.93%, respectively. As a result of sulfuric acid leaching experiments, the leaching rates of Cu and Fe were increased through decreasing the slag particle size, increasing the sulfuric acid concentration and the leaching temperature. The maximum efficiency of Cu and Fe leaching were obtained under the conditions of particle size of 32 mesh, sulfuric acid concentration of 2.0 M, and leaching temperature of $60^{\circ}C$. Accordingly, it is expected that the slag could be available as a potential and alternative resource of metallic copper.

• 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.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 1993.03a
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• pp.25.2-25
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• 1993

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.2
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• pp.162-167
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• 1983

These studies were carried out to investigate the effects of organic matter on the leaching of chemical constituents in paddy soil. Rice plants were cultured in paddy soil to which rice straw and compost were applied and then chemical properties of percolated water were analysed. The results were as follows: In the paddy soil cultured with rice plants, the pH value of soil was higher in the compost plot than in the rice straw plot. The leaching of iron, managanese, calcium, magnesium and phosphate was increased by cultivation of rice plant, but that of potassium, ammonium, and silica was decreased. When rice straw was applied in the paddy soil, the leaching of iron, managanese, phosphate and silica was increased during the growing periods, while that of calcium, magnesium, potassium and ammonium was increased by application of compost.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.2
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• pp.84-92
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• 2010

This research was conducted to investigate physico-chemical characteristics of municipal solid waste (MSW) generated from T City, Gangwon-do and leaching characteristics of the incineration ash. From the results, bulk density of MSW in T city was $231kg/m^3$. Combustible and incombustible components were in 94.0% and 6.0%, respectively. Food waste and papers in combustible component occupied 32.3% and 41.2%. Water, volatile solids, and ash content were 41.3%, 50.5%, and 8.2%. C, H, O, N, S, and Cl showed 51.4%, 6.3%, 26.7%, 1.1%, 0.2%, 0.5%, respectively. Low heating value (2,704 kcal/kg) of T city was similar to 2,764 kcal/kg of Chuncheon and was 1,000 kcal/kg higher than 1,467~1,584 kcal/kg of the past Kuro-gu and Koyang city. The specification of leaching characteristics of the incineration ash were within the Korean regulation standard.