METHOD OF PRODUCTION AND MAINTENANCE OF PROTECTIVE COAT IN OPERATING STATE OF CARBON BLOCKS CONTAINING REFRACTORY METALS Russian patent published in 2004 - IPC

FIELD: electrolytic production of aluminum; cathode units of aluminum electrolyzers. SUBSTANCE: proposed method includes delivery of materials containing admixtures of refractory metals and boron- containing compounds into electrolyzer and performing electrolysis for obtaining liquid aluminum and forming borides of refractory metals at their interaction with boron-containing compounds precipitated on carbon blocks for maintenance of protective coat in operating state. Boron-containing compounds are fed to electrolyzer together with charge and anode mass; content of boron in liquid aluminum is maintained at level not exceeding 0.01 mass-%. Protective coat is made at delivery of boron-containing compounds in the amount of 0.03-0.12 mass-% in terms of boron anhydride. Boron-containing compound are fed to electrolyzer in the amount of 0.030-0.150 mass-%. Proposed method increases yield by current by 0.8% at reduction of power requirements by 70 kW.h/t of aluminum and reduction of content of heavy metals in aluminum by (125-150)•10^-4%.. EFFECT: enhanced efficiency. 3 cl