| 摘要 |
The present invention provides a method of producing a highly pure aluminum primary base metal having a purity of at least 99.95 wt% (3N5), or a still higher purity close to the 4N that is a purity value of a secondary refined base metal. Alumina, the Si component of which is decreased by acid cleaning, is placed in a Hall-Heroult electrolysis cell as a main raw material. An aqueous solution of sulfuric acid, an aqueous solution of sulfuric acid plus hydrofluoric acid, or the like is used for acid cleaning. In order to remove Si, an acidic aqueous solution heated to at least 40 DEG C is preferred. Use of deashed coke and/or pitch as a carbon material for anode in addition to the use of acid-cleaned alumina produces a highly pure aluminum primary base metal in which the Si and Fe components are further decreased. <IMAGE> |
