Investigation of Alumina Concentration Gradients Within Hall-Heroult Electrolytic Bath

摘要

Aluminium reduction cells consume about 1.9 kg of alumina for each kilogram of aluminum they produce. Control of the alumina concentration within the electrolyte is of prime importance to achieve high metallurgical and energy efficiency and to reduce environmental footprint related to PFC and CO_2 emissions. However, modern high amperage reduction cells, oftentimes operated at much higher amperage than their nominal design, are facing challenging conditions to ensure a homogeneous alumina concentration over time and across the pot at a given time. This has negative impact on the cell efficiency. This paper presents findings from different sampling campaigns performed at different amperage and pot condition for a given cell technology. It is shown that large gradients of alumina concentration are present over time and spatially.