GB1177829A - Anodes for the Electrolytic Production of Aluminium and Aluminium Alloys - Google Patents

Abstract

1,177,829. Producing aluminium by fused electrolyte process. COMALCO ALUMINIUM (BAY BELL) Ltd. and UNIVERSITY OF TASMANIA. May 19, 1967 [May 23, 1966], No.23414/67. Heading C7B. [Also in Division C1] A mixture for the manufacture of an amount for an electrolytic cell for producing aluminium or its alloys comprises a mixture of carbonaceous material consisting of (1) Coal Tar Pitch or Oil Tar Pitch in an amount of 12-35% by weight of the carbonaceous material. (2) 88-65% by weight of calcined petroleum coke in combination with 0À5-25% (by weight, based on the total weight of mixture) of a compound selected from the oxides, carbonates and fluorides of Li, Na, K, Ca, Al and Be, or a compound of the above metals that will decompose at or below 1200‹C. to give one of the compounds mentioned. Preferred additives are A1 2 0 3 , CaF 2 , Li 2 CO 3 , CaCO 3 , LiF, Na 2 CO 3 and Cryolite. In making a pre-baked anode preferably 12-16 wt. % of Pitch and 88-84 wt. % of Coke are used in the carbonaceous material, while for a self-baking (Soderberg) anode 30-35 wt. % of Pitch and 70-65 wt.% of Coke are preferably used. A method of making the mixture comprises adding the additive compound to the calcined petroleum coke, and subsequently adding the Pitch; the anodes may then be made by baking before or as the mixture is fed to the electrolysis cell. Improved electrode life and performance are obtained with the anodes when used in electrolysis cells such as the Hall-Heroult cell. The consumption of the electrode during electrolysis results in passage of additive into the electrolyte; thus some of the metal is incorporated in the product.