• Resources Recycling
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• v.28 no.5
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• pp.51-59
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• 2019

This study focused on the synthesis of the nickel hydroxide using ammonium sulfate in leaching solution from waste nickel-cadmium batteries. The effect of pH, temperature and the input amount of ammonium sulfate in leaching solution was investigated. The ammonium nickel sulfate with high purity was obtained in acidic leaching solution and the solution temperature of $60^{\circ}C$. The suitable molar ratio of the input amount of ammonium sulfate to nickel in solution is 2:1. The impurity about 1.4 at.% of Cd was included in the nickel hydroxide precipitates when ammonium nickel sulfate was used. At the process using sodium sulfide which precipitates the cadmium in solution, nickel and iron compounds were precipitated together.

• Clean Technology
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• v.24 no.4
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• pp.315-322
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• 2018

Industrial use of waste oyster shells is limited because of requiring excessive energy for converting natural oyster shells in the form of calcium carbonate ($CaCO_3$) into calcium oxide (CaO) for this purpose. This study aimed to develop energy-saving process for producing solidifying agent using waste oyster shells for backfill materials. It was suggested that oyster shells were converted to calcium sulfates which were mixed with sodium hydroxide solution and red clay, forming solid specimen. The optimal concentrations of sulfuric acid for sulfation of oyster shell and sodium hydroxide to generate calcium hydroxide ($Ca(OH)_2$), were determined. Unconfined compressive strength of solid specimen increased with increasing the content of solidifying agent while it increased also with increasing ratio of natural oyster shells to coal ash. The result clearly demonstrates that solidifying agent consisting of sulfuric acid-treated oyster shell, coal ash, and sodium hydroxide solution, can be effectively utilized for preparing backfill materials using natural oyster shell and coal ash. Sulfuric acid-treated oyster shell-based solidifying agent has not been previously developed and will contribute to broaden industrial application of waste oyster shells.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 1993.04a
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• pp.1-23
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• 1993

중유회는 중유 화력발전소 보일러의 전지집진기에서 생성되는 분진으로 지금까지는 산업폐기물로 폐기되어 왔으나 이의 절대량이 증가하고 환경규제가 엄격하여짐에 따라 그대로 폐기할 수는 없게 되었다. 한편 이중에는 바나듐과 니켈 등의 유가금속이 3-10% 함유되어 있어 자원으로서의 가치가 충분하다. 이에 본 연구에서는 중유회로부터 바나듐과 니켈을 효과적으로 추출, 분리하여 재활용하기 위한 목적으로 바나듐과 오산화바나듐으로 니켈을 황산니켈로 각각 회수하는 방법에 관한 기초연구를 행하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2021.11a
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• pp.44-45
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• 2021

황산화물, 미세먼지 등 대기환경의 오염원은 선박이 많은 비중을 차지하고 있다. 오늘날 인간은 해양을 삶의 영역을 넓히고 있다. 하지만 해양에서 대기환경을 측정할 수 있는 방법은 제한이 되어있다. 해양에는 선박의 안전항해를 도모할 다양한 종류의 항로표지가 설치되어 있다. 따라서 항로표지를 이용하여 해양의 대기환경을 측정하여 해양과 밀접한 관련이 있는 국민에게 서비스하고자 한다.

• Landscaping Tree
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• s.109
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• pp.9-13
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• 2009

황산벌 전투. 계백장군과 5천 결사대의 항전지. 백제와 후백제의 마지막 역사를 간직하고 있는 이곳 충남 아산시 연산면 청동리에 자리한 우리 조경수협회 본회 이사이며 충남조경수유통센터의 조합장을 맡고 있는 이상권 사장의 그린농원을 찾았다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.2
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• pp.117-124
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• 2014

The interest in the use of shield TBM (Tunnel Boring Machine) on the tunnel excavation has been increased rapidly in Korea. The shield TBM tunnel is generally designed as non-drainage tunnel. Consequently, if water leakage through the segment joints happens, big problems on the usage and stability of tunnel can be occurred. In this study, the variation of waterproof capacity of hydrophilic waterstop by the construction error and excessive displacement of segment was studied firstly. Secondly, the decrease of durability of hydrophilic waterstop by the sulphate and chloride contained in the groundwater and seawater was investigated. The results showed that if the angle discordance at the segment joints is beyond the 2 degree, the proper waterproof capacity of hydrophilic waterstop can not be guaranteed. In addition, if the hydrophilic rubber waterstop is exposed to the sulphate for a while, the proper durability of hydrophilic waterstop can not be expected.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.3
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• pp.249-254
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• 1996

This research was carried out to find the suitable improvement ways of the potential acid sulfate soil(PASS) for rice cultivation through the physical applications such as surface drainage. drainage. soil dressing with common paddy soil, and burial of PASS. In reclamation of PASS the practices of surface drainage and drainage were not effective, but soil dressing with common paddy soil with same ratio and covering with common paddy soil in 30cm deep were effective for rice cultivation without growth injury. Daily drainage practice was most effective for physical reclamation of PASS.

• Resources Recycling
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• v.25 no.2
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• pp.25-32
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• 2016

A electrodeposion behavior of tin was tested to recovery of tin metal from sulfate solution using a newly designed cyclone type electrolyzer. Parameters, such as flow rate, current density, tin and sulfuric acid concentration in the electrolyte were investigated. From the experimental results, a powered tin metal below $100{\mu}m$ can be obtained. As the increase of flow rate, current density and sulfuric acid concentration in the electrolyte, electrodeposition ratio of tin and current efficiency were increased. The electrodeposition ratio of tin was increased with the decrease of tin concentration in the electrolyte, but the current efficiency was decreased.

• Resources Recycling
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• v.25 no.2
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• pp.3-9
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• 2016

Separation of Zr(IV) and Hf(IV) from sulfuric acid solutions was investigated by extraction with several acidic extractants such as Versatic acid, LIX 63, and Cyanex 301. From strong sulfuric acid solutions, the separation of Zr(IV) and Hf(IV) by Versatic acid and LIX 63 was not possible, while selective extraction of Hf(IV) over Zr(IV) was obtained with Cyanex 301. However, the extraction percentage of the two metals was much lower compared to that by D2EHPA. Mixing of TBP with Cyanex 301 and D2EHPA led to negative effect on the extraction and separation of the two metal ions. The difference in the extraction reaction and separation selectivity between HCl, $HNO_3$ and $H_2SO_4$ media with each extractant was discussed.

• Journal of the Korea Institute of Building Construction
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• v.11 no.6
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• pp.547-556
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• 2011

The primary factors affecting concrete sulfate resistance are the chemical composition of the Portland cement, and the chemistry and quantity of mineral admixtures. To investigate the effect of those on the sulfate attack, the testing program involved several different mortar mixes using the standardized test, ASTM C1012. Four different cements were evaluated, including one Type I cement, two Type I-II cements, and one Type V cement. Mortar mixes were also made with mineral admixtures, as each cement was combined with three different types of mineral admixtures. One Class F fly ash, one Class C fly ash, and one ground granulated blast furnace slag (GGBFS) were added in various percent volumetric replacement levels. Expansion measurements were taken and investigated with the expansion criteria recommended by ASTM.