GB225494A - Improvements in or relating to methods of operating and lining electrolytic cells for electrolytic refining - Google Patents

Abstract

225,494. Aluminum Co. of America, (Assignees of Tilson, D. H.). Nov. 30, 1923, [Convention date]. Aluminium, obtaining. - A process of putting an electric cell in condition for refining a metal comprises establishing in the cell in suitable order upper and lower metallic layers 36, 34 of different densities and an intermediate layer of electrolyte 33 of intermediate density, and before the layer 36 is established freezing a crust from the electrolyte on to the sides of the cell to serve as part of a side lining 32 and after the layer 36 is established completing the formation of the lining. The cell comprises upper and lower steel shells 11, 10 insulated from one another and provided with water jackets 14, 13. The shell 10 has a carbon bottom 24 provided with a conductor 26 and resting on a layer of bauxite 23. When refining aluminium the electrodes 29 are lowered into contact with the carbon bottom and current is passed to raise the latter to red heat. The cell is then charged with an electrolyte consisting of sodium and aluminium fluorides with the addition of barium and/or strontium fluorides and current is passed therethrough. Sufficient anode alloy, consisting of aluminium, copper, and silicon is then added in a molten or solid form to raise the level of the electrolyte above the joint between the shells. The cooling action of the jackets causes the formation of a crust 32 on the sides of the cell and covering the joint. The cathode metal consisting of part aluminum is now added by pouring it slowly on the asbestos board inclined at an acute angle to the cell. The electrolyte creeps up the side of the cell by capillary attraction and solidifies thereon to complete the formation of the lining on the part surrounding the cathode.