The double-stream alumina digestion process is a key production chain in Bayer process of alumina production. It is the unique production technology in China. However

the double-stream alumina digestion process has problems that the evaporate water capacity of flash vessel is not fully exploited

scaling causes increased new steam consumption

meanwhile

working points are set manually

which causes the high energy consumption. Thus

the exergy optimization model of the double-stream alumina digestion is established

and the digestion process is divided into three stages based on the degree of scab in a pickling cycle. An adaptive state transition algorithm is proposed to optimize the operating parameter of the three stages of the digestion process

respectively. Then

optimal process control parameters are obtained

which is meaningful to provide suggestions for practical production.