THE IMPACT OF BATH RATIO CONTROL IMPROVEMENTS ON CURRENT EFFICIENCY INCREASE

摘要

Current efficiency, one of the most important factors for primary aluminum production, is mainly determined by bath composition, bath temperature, current density, anode cathode distance (ACD) and cell design. According to Six Sigma concepts, to reduce the output variation it is necessary to reduce the input variation. Therefore for consistent current efficiency, the bath composition, bath temperature and ACD must have tight control in order to reduce their variation and keep them on target. This paper describes the Novelis process team's experience since 2002 working to improve potline performance. In the last four years the current efficiency has increased by about 1.7% and the current has been increased about 1.3 kA through process control improvements. This paper focuses on the impact of bath ratio control improvements on current efficiency increase and the operational changes that have contributed to drive the percentage of pots in bath ratio target above 85%.