Research On Rule And Prevention Of Periodically Attenuating Of Product Particles In Precipitation Process Of Sodium Aluminate Solution

Alumina is the main material for production of electrolyzed aluminum, at the same time, it is the indispensable raw material for electron, petroleum, chemical engineering, refractory material, ceramic etc. In recent years, sand alumina with many merits becomes most popular material in modern industry with the use of big type of pre-bake electrolysis cell and environment protection. For meeting the requirement of world market, many organizations and enterprises on alumina field have done many works. At present, particles and intensity of alumina production are significantly meliorated. But periodical attenuation of particles, which interferes seriously with the normal alumina production of Bayer, exists in the alumina production process of Bayer method all the while. Therefore, to solve periodical attenuation of particles in Bayer process is the impending question for Chinese alumina industry. This paper systematically studied the rule and prevention of periodical attenuation of production particles.The paper systematically studied the rule, conditions and effect factors of periodical attenuation by simulating the real production in laboratory. And also the mechanism was analyzed with the SEM photograph. The results showed that periods of Al(OH)₃ particle size variation shortened with rising of temperature and lengthened with increasing of solid content, and that the amplitude of the particle size fluctuation reduced with rising of temperature and enhanced with increasing of solid content. Unbalance of particle size distribution, that the particles became gradually bigger, induced the specific surface area of seeds smaller, which are the major conditions causing explosive attenuation of seed precipitation.Successionally adding fine seed (Al(OH)₃) to seed precipitation process in different time to stabilizing fluctuation of Al(OH)₃ particles was suggested. The experiment indicated that Al(OH)₃ production with well particle size can be obtained by adding fine seed of 60g/L or so in attenuation metaphase, while in coarse metaphase adding fine seed accelerated attenuation of production particles with.The paper systematically studied effects of carbonization seeds on seed precipitation process of sodium aluminate solution by simulating the real production in laboratory. Results showed that adding carbonization seeds to Bayer process enhanced pre-...