Shandong Aluminum Corporation Of The Second Alumina Plant Of Sandy Alumina Decomposition Transformation Project,

In the industry of aluminium smelter, it is requested to reduce electrolyser- operating temperature, to control environment pollution, to increase automation level, etc with the wide application of large prebaked electrolyser and dry method purification. Therefore, the higher and higher quality alumina is needed. The sandy alumina occupies the leading position in the market because of its feature of good fluidity, sensitive dissolution, high intensity, strong absorptivity to HF, and big and well particle size distribution. In contrast, the powder alumina with low specific surface area, too much small particle size, low intensity and easy to be damaged, are fully unfit for high efficiency dry method purification technology. The major alumina corporation in the world has finished the sandy alumina reform by now, and the market of powder alumina is changing very small.Long since, the alumina products in China appear powder or moderate status, and only can be used on the soderberg anode cells line. After acceding to WTO, and with the development of domestic aluminium smelter industry, much more sandy alumina come into China, which give a strong impact to China's alumina corporation. In order to close to the world advanced producing level, also to develop our own alumina industry, the combined CHALCO puts forward the reform plan of sandy alumina, and will turn our exiting alumina into sandy one.SALCO has two alumina factories with moderate status products.The company has done a lot of work to realize the sandy alumina reformation, and has developed different schemes according to their own features. This article mainly talks about the scheme of the sencond factory. Before and after the reformation, this factory's capacity is 200 and 320 thousand ton per year, respectively. Therefore, the project is not only a reformation but also enlarging the capacity one.A process called as "two section method" is used in the reformation, which includes a high temperature agglomeration and a low temperature growth to replace the traditional "one section method" used in the present line. The following aspects have been concerned in reformation: 1. Adopting high temperature agglomeration and further consolidating low temperature growth, 2. Prolonging the decompose time from 36 hours to 45 hours, 3. Decreasing the temperature in the middle, 4. Strengthening the classification of coarse/fine seed and finished products, 5. Using the advanced seed and the finished product filtering equipments, 6. Synthetically analyzing the crystal seed nucleation and growth with the advanced electrosensitive particle meter and laser particle meter.Since the project was put into production in March 2005, it has obtained the expected effects, such as solution of the issue of the periodic undulation of particle size, decrease of the -45μ size of hydro-alumina from 20%-40% to less than 6%, the size of finished alumina product controlled in -45μ less than 18%, and remarkable increase in the abrasion index.