Bubble noise from Soderberg pots

High frequency measurements of voltage were introduced at Elkem Aluminium Lista in order to find the effect of noise from the release of gas bubbles under the anode - bubble noise. On a Soderberg pot the bubble noise represents a fairly large portion of the total pot noise. Hence it is important to understand what impacts the bubble noise in order to understand and control the Soderberg pot in a better way. The bubble noise varies quite a lot over time and between pots. The variations are related to different process conditions. Looking at number of anode problems and carbon dust generation there is a correlation between the bubble noise and the quality of the Soderberg anode. The metal quality is also strongly impacted by a change in the bubble noise. Several process conditions have been investigated, presented and discussed in the paper.