| 摘要 |
PURPOSE:To prevent detaching of mold lubricant and to enable continuous and repeated use of a crucible by forming the inner face of crystallization part into the specific surface roughness on the side wall of the carbonaceous crucible for Al refining apparatus by fractional crystallizing method. CONSTITUTION:The mold lubricant composing of graphite grains having about 0.5-1.0mum average grain size is applied on the inner surface of a carbonaceous crucible. Molten Al is charged in this crucible to segregate and solidify pure Al on the cooling face of the inner surface. Next, after discharging remained molten Al mother liquid, solidified shell is scraped and taken out by sliding a piston. In the carbonaceous crucible for the Al refining apparatus by the fractional crystallizing method, the inner face for crystal precipitating part on the side wall is 50s-500s surface roughness. The roughness is desirably provided with obtd. by forming the surface to screw grooves having 50-500mum in height (h) and 1h-10h in pitch. By this method, the sticking of Al to carbon is prevented without losing the mold lubricant at the time of sliding of the scraping piston, and the crucible can be repeatedly used without any damage.
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