Study On Industrial Low Temperature Aluminum Electrolysis In 240 KA Prebaked Cells

The lower temperature aluminum electrolysis is a creative technology for primary aluminum production.It has a significant effect on increasing current efficiency and decreasing DC energy consumption.Lower temperature electrolysis is a intensively studied topic in the world,which has a great impact on innovations in the field of aluminum production.Based on the present situations of China aluminum industry,the author carried out a industrial test of lower temperature electrolysis by using electrolyte-containing MgF2.The test was conducted in several 240kA aluminum prebaked cells.Over half a year test,impressive results were obtained with average current efficiency increasing of 0.5%and DC energy consumption decreasing of 300kWh/t Al.Through this industrial test,two key problems related to the lower temperature electrolysis were solved.The main conclusions can be summarized as follows:(1)Nine-zone strategy for electrolysis temperature control was practiced to control bath temperature and bath superheat.Industrial test confirmed that superheat control band should be in the range of 10-15?,which is a key for running the cells stably.(2)Industrial test confirmed that alumina control band should be in the range of 2-4%,which enable the highest current efficiency and lowest anode effect efficiency.(3)Some rules for controlling alumina feeding were made according to the industrial test of lower temperature aluminum electrolysis.It is very important to control the alumina concentration in a proper range for avoiding sludge formation at higher concentration and anode effect at lower concentration.The thesis presented some basic data and rules on lower temperature aluminum electrolysis,which are benefit for energy saving and pollution reduction for aluminum industry in China.