INITIATIVES TO REDUCE ANODE EFFECT FREQUENCY AT DUBAL

摘要

Extensive studies have been carried out in smelters aroundrnthe world to understand the fundamental cause of an anoderneffect. The exact nature of the onset of an anode effect isrnstill shrouded in mystry. However, the consensus is thatrnanode effects are detrimental to cell operation; they resultrnin reduced energy consumption and cause emission of CF4rnand C2F6 gases.rnWith the intention of reducing carbon footprint, there is anrnexcellent opportunity to reduce anode effects and thernresulting PFC emissions.rnOccurrence of an anode effect was studied in relation torndifferent aspects; alumina feed rate, work schedule,rncathode type, operating parameters, mechanical issues, etc.rnOnset of an anode effect was primarily due to inability ofrnthe response strategy to deal with it efficiently. Aluminarnfines and pencilling of crust breaker tip were the otherrnreasons.rnA strategy to kill an incipient anode effect was developedrnand implemented. Consequently, AE frequency hasrnimproved by more than 50%. The logic is very promisingrnas it lowers alumina concentration whilst effectivelyrnreducing anode effect frequency. Lower aluminarnconcentration is conducive to improving current efficiency.rnThe strategy is being fine tuned to achieve a sustainedrnanode effect frequency of <0.05.