• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.202-208
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• 2001

Aluminum dross should be recycled in consideration of characteristics of the dross and its reutilization after processing. In this study, aluminum dross generated in the domestic secondary aluminum industry was processed to use it as raw material for producing aluminum hydroxide. Sample dross was classified according to its size. The dross smaller than 1mm was leached with sodium hydroxide solution to extract the remaining aluminum from the dross into the solution, and then aluminum hydroxide precipitate was recovered from the leach liquor. Purity of the obtained aluminum hydroxide was above 98 percent, and particle size of the sample was in range of 3-39${\mu}{\textrm}{m}$. From the result, it was suggested that this process could be applicable to recycling of aluminum dross.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.97-97
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• 1999

Dross formation in the zinc bath is inevitable under any condition as long as coating process on steel strip continues. Thus, bath aluminum and temperature are precisely managed to suppress the increase of dross. Also, excessive dross for normal coating process is generally eliminated physically by bubbling and skimming. Total amount of dross in the bath can be sometimes high enough to cause coating defect. On the other hand, local concentration of dross can make coating defect even with satisfactory level of total amount of dross. Reduction of dross in the bath was attempted by using ceramic foam filter made of mainly alumina. Dross in molten zinc was almost reduced to the levels of solubility of iron and aluminum in molten zinc at $450~460^{\circ}C$. Their solubility levels were confirmed by thermodynamic calculations or DEAL program. Two kinds of filters were tested for dross reduction. One was #20 ppi, porous per inch, and the other #30 ppi filter. Both were effective in reducing the bath dross to the solubility levels at the static state. Bath iron was reduced by 24 wt% and 19 wt% with #20 filter, and by 35 wt% and 29 wt% with #30 filter for GI and GA pot, respectively. Also, ceramic foam filter did not make any harm to the zinc bath composition after filtering test.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1488-1491
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• 1996

Throughout CGL(Continuous Galvanizing Line) in steel works, zinc-coated steel sheets are produced which are used where long-running corrosion resistivity is required. During the galvanizing process, top dross is created and floated on the zinc pot. Because the dross leaves ill patterns on the coated sheets, it is removed manually with shovel-like tools in about twenty minutes. Because, however, the working environment is very noisy, hot and harmful to human workers, a robot system is developed and implemented on a real plant to automatically remove the top dross. It consists of a robot and its carriage system, a pot level sensor, a system controller, and special tools to collect, pick up, and put the top dross into a dross waste basket. A system software is developed to monitor the system status. A series of tests were performed to verify the robot motion and adaptation to working conditions, and proved successful work.

• Corrosion Science and Technology
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• v.11 no.3
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• pp.71-76
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• 2012

Computational fluid dynamics (CFD) is nowadays a powerful and reliable tool for simulating different flow processes and temperature. CFD is used to analyze the various pot geometries and operative variables in 55% Al-Zn pot of CGL. In this research, different strip velocities were assumed and then shown the flow pattern in the pot that was similar in the different strip velocities. Temperature distribution in the pot depended on inductors and inlet strip temperature at the steady condition. Generation of dross particles and transport models were considered to describe dross particles evolution inside the pot. In order to observe dross influence by scrap location, dross particles were generated upon the sink roll. Floating time of dross particles is different by scraper locations above the sink roll.

• Journal of the Korean institute of surface engineering
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• v.34 no.4
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• pp.313-320
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• 2001

It is well known that the amount of hot-dip Zn coated sheet steels used for automotive is rapidly increasing. As hot-dip steel sheets show good corrosion resistance and excellent formability, the demand for outer panel of automotive has been increased in order to satisfy with the requirement of high surface qualify. There are many kinds of factors influencing on the surface quality and the dross control in the galvanising bath is regarded as one of the most important thing. In this study the characteristic and growing behavior of dross in the galvanizing bath were investigated and the effect of dross on the surface defect of GA was surveyed. The dross defects on the GA sheet steels result from bottom dross whose diameter are larger 50$\mu\textrm{m}$ in the Zn pot. Dross-free state exist for about 30 hours from starting time of GA production.

• Resources Recycling
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• v.27 no.5
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• pp.61-68
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• 2018

The aluminum dross is oxide generated on the surface of the molten metal during the aluminum melting process and it is divided into white dross and black dross according to presence of the Salt flux. White dross has high metal content and is recycled via the melting process. Black dross is largely berried, because the it has a low metal content and difficulty in separating the components. Black dross contains a salt components such as NaCl and KCl, and inorganic materials such as $Al_2O_3$ and MgO, and it is necessary to study the technology to recover and recycle such valuable resources. In this study, a process for recycling aluminum black dross was proposed. The inorganic and soluble substances present in the black dross were separated through crushing-dissolution-solid/liquid separation-decompression evaporating. By controlling the ratio of water and black dross, the recovery condition of the separated product was optimized and we confirmed the highest Salt flux recovery efficiency 91 wt.% at black dross:water ratio 1:9. Finally, Through the synthesis of zeolite using recovered ceramic material, the materialization possibility of black dross was confirmed.

• Journal of the Korean institute of surface engineering
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• v.36 no.6
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• pp.466-474
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• 2003

To develop a method of detecting dross in coating layer on hot-dip galvanizing steel, chemical etching behavior of the artificial coating layers with top and bottom dross were investigated. After chemical etching with the mixture of picric acid and sodium thiosulfate, each of the top and bottom dross take its distinct color, and alloy layer in coating is also observed. Defects in the coating layers of HGI(hot rolled galvanized iron), CGI(continuous galvanized steel sheet) and GA(galvannealed steel) were analysed, and methods of dross detection which can be applied to inspection process in manufacture were suggested.

• Resources Recycling
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• v.10 no.5
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• pp.8-15
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• 2001

Aluminum dross should be recycled in consideration of characteristics of the dross and its reutilization after processing. In this study, aluminum dross generated in the domestic secondary aluminum industry was processed to use it as raw material for producing aluminum hydroxide. Sample dross was classified according to its size. The dross smaller than $850\mu$m was leached with sodium hydroxide solution to extract the remaining aluminum from the dross into the solution, and then aluminum hydroxide precipitate was recovered (rom the leach liquor. Purity of the obtained aluminum hydroxide was above 98% and size of the sample was in range of $\3~39mu$m. Recovery of aluminum hydroxide precipitate was highest on condition that A/C ratio of the solution was 0.5 and pulp density was 14~16% at the leaching step. From the result, it was suggested that this process could be applicable to recycling of aluminum dross.

• Resources Recycling
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• v.12 no.3
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• pp.46-53
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• 2003

Recycling of aluminum dross is an important issue in the secondary aluminum industries. In this study, aluminum dross generated in the domestic secondary aluminum industry was processed to use it as raw material for producing alumina refractories. Sample dross was classified according to its size. The dross smaller than 1 mm was leached with sodium hydroxide solution to extract the remained aluminum from the dross into the solution. and then aluminum hydroxide precipitate was recovered from the leach liquor. The waste residue in the leaching was washed, dried and roasted. Most remained metallic components in the residue was changed into oxide through the processes. The roasted dross was made into alumina castable refractories by mixing with aggregates and a binder. Bending strength of the tested castable specimen was over $25\;kg/\textrm{m}^2$ and compressive strength over $80\;kg/\textrm{cm}^2$, which satisfied the Korean Standard value respectively. From the results, it was suggested that this process could be applicable to recycling of aluminum dross.

• 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.