Productivity Increase at Søral Smelter

The Sor-Norge Aluminium A/S (SORAL) smelter was started in 1965 with Alusuisse 100kA pre-baked anodes technology. In 1989 it was decided to bring the plant up to date, no modifications having been made since start-up. The objectives of the initial modernization project were quite modest: to increase the current level from 105 to 115 kA, current efficiency from 90 to 92 % and to decrease energy consumption from 15.3 to 14.7 kWh/kg Al. These goals were to be reached by introducing a new cathode shell and lining design, by making minor modifications to the busbars, and by installing new process control and point feeding. These changes improved performance and pointed the way to yet further improvements. Today Soral is operating both pot lines at 126.5 kA with a current efficiency of 93.6% and a specific energy consumption of 14.8 kWh/kg. Ten test cells have been operating for more than 17 months at 140 kA and, with the cooperation of the Alusuisse Technology Center Chippis, Soral is exploring the possibility of operating the cells at 150 kA. The ultimate goal is to operate the whole plant at 150 kA with 94% CE and a specific energy consumption of 14 kWh/kg by 2005. This paper presents the developments and methodology in detail, showing the results achieved to date and discussing possible future developments.