Research And Design On The Dissolution Process With Pre-desilication

With the fast development of aluminum industry in recent years in our country, China has been the second major alumina production in the world currently. The raw bauxite in China is meager and most of them is diasporic, therefore the process to produce alumina is complex and has high energy consumption. Aluminum product using raw bauxite of bayerite was imported from overseas in our country from last century, and the scale of production was continually expanded in recent years. The dissolution process is the key to the process, which not only consumes more than 50% steam of the whole process, but also has an important factor to determine the quality of parameters of process.The advantage and feasibility of the dissolution with desilication ahead process are proposed by analyzing the theory of raw bauxite dissolution and the test data. The new dissolution with pre-desilication process technical is proposed in the paper, which time difference between the bayerite dissolution and desilication reaction of dissolve dissolved silicon is fully used. Firstly the mineral strach is heated to the 95～105℃of normal-pressure desilication by the piping technique, combining a heat preservation 6～8 hours, as a result,above 70% desilication is finished in the pre-desilication tank, then the mineral strach is heated to 145℃in the pipe and dissolution is finished.With the shortcoming of the dissolution process by one pipe analyzed, the system of self-evaporation is optimized and the ability of energy distributed of self-evaporation is improved, and hot utilization is raised, changing hot area of preheater is reduced by using the technology that hot water is self-evaporated and the steam heat the mineral starch. And the three-pipe changing hot set is chosen as changing indirectly hot set in the process.Process calculation is finished according as the technology of dissolution with pre-desilication process in the paper. According to the technical condition the dissolution with pre-desilication process design is completed. The new steam consumption could be reduced above 10% in the dissolution process by the production line built as the design. The running time of three-pipe changing hot set reaches more.The new dissolution with desilication ahead process using three-pipe changing hot set is used, self-evaporation is optimized. Witch reduced energy consumption and achieved large scale equipments and automation. It is an important guiding significance to alumina production using raw bauxite of bayerite imported from overseas in our country.