• 대한환경공학회지
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• 제38권1호
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• pp.1-7
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• 2016

무전해 니켈 도금 산세 폐액을 강화된 니켈의 배출허용기준 3.0 mg/L 이하로 처리하기 위해서는 기존 처리방법의 단점을 보완한 처리방법의 개발이 필요하다. 용성전극 및 불용성전극을 이용한 전기분해 처리방법은 공통적으로 무전해 니켈 도금 산세 폐액을 효과적으로 처리할 수 있다. 그러나 용성전극은 전극으로부터 금속이 잘 용출되는 특징을 갖는 반면 불용성전극은 금속이 용출되지 않는 차이점을 갖고 있어 니켈 제거 효율 및 니켈 슬러지 순도에서 서로 다른 장단점이 존재한다. 이에 본 연구에서는 용성전극 및 불용성전극을 이용한 전기분해 방법으로 무전해 니켈 도금 산세 폐액을 처리하기 위한 최적조건을 도출하고, 두 전극을 이용한 방법의 장단점을 조사하였다. 실험결과 불용성전극을 사용하였을 때 처리수의 효율적인 니켈 제거를 위한 최적조건은 전류밀도 $15mA/cm^2$ 이상, pH 9 이상으로 도출되었고 이 조건에서 니켈 슬러지의 순도는 95.3%로 나타났으며, 슬러지 내 철 함량은 2.9%로 조사되었다. 용성전극을 사용하였을 때의 최적 조건은 전류밀도 $10mA/cm^2$ 이상, pH 9 이상으로 도출되었으며 최적조건에서 니켈 슬러지 순도는 77.3%, 슬러지 내 철 함량은 21.0%로 조사되었다. 처리비용을 기존의 처리비용과 비교하여 용성전극 사용시 50.7%, 불용성전극 사용시 24.2% 저감시킬 수 있는 것으로 조사되었다.

• 한국표면공학회지
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• 제32권3호
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• pp.219-223
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• 1999

A new additive for semi-brightness finish in nickel electroplating, having a quarternary ammonium salt structure, has been developed in this study. The effectiveness of the new additive was tested in laboratory-scale eletroplating tests as well as in a full-scale factory plating line. An examination of the plated surface showed that the new additive is as good as the one produced by the most commonly used additive in the nickel plating industry. The plated surface was examined by SEM, EPMA, and Reflectance Spectroscopy, and was found to be compatible to the one obtained with commercial additives. The new additive has a shelf life comparable with those of other commercially available additives. The additive developed in this study has an excellent potential to be used commercially.

• 연구논문집
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• 통권31호
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• pp.127-133
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• 2001

In chromium electrodeposition, crack is inevitably accompanied by chromium layer. Behavior of crack formation and crack density were different from the plating conditions such as current density, temperature, waveform of applied current and so on. And cracks have an influence on the corrosion resistance of chromium deposit, because corrosion occurs through the network of cracks between deposit and substrate. Therefore, many researches have been achieved in order to remove the cracks in chromium deposit. Formation of double layers, Cr/Cr and Ni/Cr were investigated to increase corrosion resistance of chromium deposit in this study. As pretreatment prior to outer chromium coating, acid pickling and current control method were examined. Cracks in cross-section of each sample were observed with SEM and CASS(Copper modified acetic acid salt spray) test was performed to evaluate corrosion resistance. It was found that corrosion resistance of Cr/Cr and Ni/Cr double layers were superior to Cr or Ni single layer from the results of CASS test.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.259-263
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• 2001

There are several steps such as slicing, lapping, chemical etching and mechanical polishing in the silicon wafer production process. The chemical etching step is necessary to remove damaged layer caused In the slicing and lapping steps. The typical etching liquor is the acid mixture comprising nitric acid, acetic acid and hydrofluoric acid. At present, the waste acid is treated by a neutralization method with a high alkali cost and balky solid residue. A solvent extraction method is applicable to separate and recover each acid. Acetic acid is first separated from the waste liquor using 2-ethlyhexyl alcohols as an extractant. Then, nitric acid is recovered using TBP(Tri-butyl phosphate) as an extractant. Finally hydrofluoric acid is separated with the TBP solvent extraction. The expected recovered acids in this process are 2㏖/l acetic acid, 6㏖/1 nitric acid and 6㏖/l hydrofluoric acid. The yields of this process are almost 100% for acetic acid and nitric acid. On the other hand, it is important to recover and reuse the metal values contained in various industrial wastes in a viewpoint of environmental preservation. Most of industrial products are made through the processes to separate impurities in raw materials, solid and liquid wastes being necessarily discharged as industrial wastes. Chemical methods such as solvent extraction, ion exchange and membrane, and physical methods such as heavy media separation, magnetic separation and electrostatic separation are considered as the methods for separation and recovery of the metal values from the wastes. Some examples of the application of solvent extraction to the treatment of wastes such as Ni-Co alloy scrap, Sm-Co alloy scrap, fly ash and flue dust, and liquid wastes such as plating solution, the rinse solution, etching solution and pickling solution are introduced.

• 한국산업보건학회지
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• 제15권1호
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• pp.36-44
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• 2005

A push pull hood system is frequently applied to control contaminants evaporated from an open surface tank in recent years. Efficiency of push pull hood system is affected by various parameters, such as cross draft, vessel shapes, size of tanks surface, liquid temperature, and so on. Among these, velocity of cross draft might be one of the most influencing factor for determining the ventilation efficiency. To take account of the effect of cross draft velocities over 0.38m/s, a flow adjustment of ${\pm}$20% should be considered into the push and +20% into the pull flow system Although there are many studies about the efficiency evaluation of push pull hood system based on CFDs(Computational Fluid Dynamics) and experiments, there have been no reports regarding the influence of velocities and direction of cross-draft on push-pull hood efficiency. This study was conducted to investigate the influence of cross draft direction and velocities on the capture efficiency of the push-pull ventilation system. Smoke visualization method was used along with mock-up of push-pull hood systems to verify the ventilation efficiency by experiments. When the cross-draft blew from the same origins of the push flows, the efficiency of the system was in it's high value, but it was decreased significantly when the cross-draft came from the opposite side of push flows Moreover, the efficiency of the system dramatically decreased when the cross-draft of open surface tank was faster than 0.4m/s.