• Korean Journal of Materials Research
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• v.8 no.2
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• pp.126-130
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• 1998

Aluminum sulfate, $AI_{2}(SO_4)_3\cdot18H_2O$ was prepared by adding of kaolin-dissolved sulphuric acid into ethanol and its thermal decomposition behavior was discussed. As-synthesized high purity precipitate particles were platelike shapes of $2\mu\textrm{m}$ size. With increasing drop rate of leach liquor into ethanol, the crystallite sizes of the precipitate decreased. The apparent activation energies for dehydration and sulfate decomposition of the precipitate were $11.9Kcal mol^{-1}$ and $48.2kcal mol^{-1}$ respectively.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.54-57
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• 2004

알루미늄 용해반사로 gas 배출기의 bag cage에서 사용 6개월만에 균열이 발생하였다. 이러한 bag cage의 용접부에서 발생한 균열의 원인조사를 위해 bag cage의 성분분석, 용접부에서의 파단면과 미세조직을 SEM과 금속현미경으로 관찰한 결과 bag cage의 균열의 원인이 배기가스중의 황화물과 대기중의 습기, 산소와 반응에 의해 형성된 Polythionic acid이 생성되어 용접에 의해 예민화 된 부위에 부식을 일으켰다는 것을 확인할 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.5
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• pp.462-465
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• 2004

After 6 month of using, cracking of gas exhaustion bag cage of Type 304 stainless steel wire for Al melting reverberatory furnace was founded in welds. Analysis of crack causes in the wire were tested by electrochemical method, SEM images of structure and analysis of composition. Resulted from the test, it could be observed that cracks in the welds were a accelerated by formed polythionic acid on surface of bag cage in sensitized region of HAZ, tensile stress and using environment.

• Resources Recycling
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• v.9 no.6
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• pp.53-57
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• 2000

In the present paper, a current technical progress for recycling of used steel can is described. The developed technology was a kind of pre-treatment through an automatic equipment system to increase recycling and melting efficiency of used steel co. The process consisted of several unit processes such as breaking of steel can bale, removing dust, separation of aluminum can, delacquering, and compressing to bale. Also, aluminum powders were recovered as a by-product at the delacquering step. The process was carried out automatically through by use of the developed equipment system. The automatic system could be very available in mass treatment of used steel can.

• Resources Recycling
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• v.13 no.3
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• pp.50-57
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• 2004

Waste aluminum dross is a major waste in the aluminum scrap smelters and its components are mostly alumina and remained metallic aluminum. In the process to extract the remained aluminum from the waste dross by leaching with sodium hydroxide solution, residue is generated and its main component is alumina. This residue could be recycled into ceramic materials such as alumina castable refractories by going through a series of treatments such as washing, drying and roasting. In this study, a pilot plant was constructed and tested to demonstrate the developed technology. One thousand tons of waste aluminum dross could be processed, and about seven hundred tons of ceramic materials produced in the demonstration line. From the test run of the pilot plant, although it was confirmed that the developed technology could be applied to commercialization, several technical improvements were found to be necessary for reducing impurities such as Na, Fe and for reforming drying equipment.

• Journal of the Korean Chemical Society
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• v.35 no.4
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• pp.414-421
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• 1991

High-purity alumina powder was prepared by extracting the natural alumino-silicate mineral (halloysite) in H$_2$SO$_4$ solution. For the selective precipitation of alum and aluminum hydroxide, the solubility diagram was prior calculated by also considering the formation of hydroxides and carbonates for all the metal ions in an aqueous solution, which allow us to control the contamination of impurities envolved in the natural minerals. Ammonium aluminum sulfate (alum) and alumium hydroxide could be successfully prepared at pH = 1.5∼2.5 and pH = 6∼8, respectively according to our solubility diagrams. The purity of alum-and hydroxide-derived ${\alpha}-Al_2O_3$ was determined to be 99.7${\%}$ and 99.0${\%}$, respectively, which indicates the former route would be more desirable for the large scale application. It is also worthy to note that the impurities like Na and Si were strongly reduced in the former (Na = 0.05${\%}$, Si = 0.09${\%}$) compared to the latter (Na = 0.29${\%}$, Si = 0.12${\%}$).

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.131-134
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• 2015

국내 천연가스 열량제도를 현행 표준 열량제 $10,400kcal/Nm^3(43.54MJ/Nm^3)$에서 중간 조정기간을 두고 2012.07.01부터는 최저 $10,100kcal/Nm^3(42.28MJ/Nm^3)$을 유지하고 2015년 이후 $9,800(41.1MJ/Nm^3){\sim}10,600kcal/Nm^3(44.4MJ/Nm^3)$ 열량범위제도로 변경 추진되고 있다. 산업현장에서 열량변동을 측정하여 공연비 제어기술을 개발하고자 60ton Al 용해로에 열량대응기술 개발을 위한 내용으로 열량측정시스템설치 및 열량 값과 연계하여 공연비 제어기술개발연구 내용으로 결과는 다음과 같다. 단순히 표준열량으로 에 맞춰 프로그램된 제어로직에 열량변동에서 검출된 신호를 이용하여 연료보정 값을 추가한 로직을 재구성할 필요가 있다. 이 혀장의 경우는 용탕의 온도가 목표온도 근처까지 올리기가 어려워진 상황으로 주로 공급열량 저열량화에 따른 과잉공기영향으로 온도상승이 어려워 보이며 적절한 공연비로 최적화 되면 이러한 문제가 개선되리라 생각된다.

• Resources Recycling
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• v.7 no.3
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• pp.42-51
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• 1998

Hydrogen in atmosphere can easily dissolve in melt of light metal alloys. Increasing demand for recycling of light metal a alloys has, therefore, focused attention on the removal of hydrogen gas, and alloy addition in melt has become an imporLant r refining process. For this purpose behaviors of mixing and hydrogen degassing in impeller agitated refming vessel with/without barnes were investigated. Flow patterns, mixing time behavior and kinetics of degassing in various agitating conditions were analysed in watet model experiments. And, numerical analysis on turbulent flow pattern in impeller agitated vessels was performed.

• Resources Recycling
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• v.5 no.1
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• pp.14-20
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• 1996

For recycl~ng alumhx~rn dross, the cbaraclcrislics of dross and ils reutll~zalin~af~te r plocsssing should he considered. Nurn~llumd ross was classified according to iB sire in this shldy. Tbe dross larger Illan 3001~1w as directly re-meltcd to recover aluminum, and the s~nallerd ~ossw as leachcd and riln~tedl o scparalc 111s eri~lerls alt and to oxidize the rnelals contained in the dross. As a rcwlt, amount of the dross uscd lo be dircarded ahcr processing could hc reduced Also, lhc chem~cal culnposit~ons of a domzstic alumlnum dross and the changes in con~posilii~ndsu ring processings were investigated. and Cound that most mctaU'ic aluminum in the dross was changed inlu alu~n~numox ide lhruugli the roasting. Tile processed dross would he ulillzed for malerials such as alumina, alumma cemenl or tilcs.

• Journal of Korea Foundry Society
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• v.43 no.6
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• pp.286-293
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• 2023

In this study, we investigated the microstructural evolution of Al-Mg-Zn aluminum alloy billet during homogenization treatment using OM, SEM, EDS and DSC. There were numerous phases found, such as; AlMgZn, AlMgFe, and AlMgZnSi phases, in the grain of the cast billet. After 6 hours homogenization treatment, Zn was mostly dissolved, whereas, Mg and Si were only partly dissolved. Accordingly, only AlMgFe and AlMgSi remained. After 18 hours, all of the leftover Mg and Si were dissolved, leaving only AlMgFe, which was also found after 24 hours. The results of the alloy design program, JMatPro showed that Mg dissloved more rapidly than Zn. According to the homogenization kinetic equation, Mg and Zn are completely dissolved within 1.9 and 3.5 hours, respectively.