分解过程氢氧化铝产品粒度变化机理及规律

在拜耳法氧化铝生产中粒度依然存在着周期性细化现象,严重影响到拜耳法系统的正常运行.为了解决周期性爆发性细化问题,模拟工业条件对种分过程产品的周期性细化进行研究.结果表明:产品氢氧化铝粒度变化的周期随温度的升高而缩短,随晶种量的增加而延长;粒度波动的振幅随温度的升高而减小,随晶种加入量的增加而增大;在其它条件基本不变的情况下,用于分解的晶种粒度分布出现断层造成其分布不平衡,特别是细粒子减少,粗粒子增多,导致种子的比表面积变小,以至于分解后期种子的比表面积小于某一临界值,从而导致产品粒度的爆发性细化.在此基础上对产品粒度周期性细化的机理做了进一步的探讨.

Mechanism and rule of Al(OH)3 particles variation in seed precipitation

Periodical attenuation of particles,which interferes seriously with the normal alumina production of Bayer method,exists in the alumina production process of Bayer method.In order to solve this problem,the reasons of the periodical attenuation of particle size were analyzed by simulating the real production.The results show that the period of Al(OH)_3 particle size variation shortens with rising of temperature and lengthens with increasing of solid content,and that the amplitude of the particle size fluctuation reduces with rising of temperature and enhances with increasing of solid content.Unbalance of particle size distribution,that the particles become gradually bigger,induces the specific surface area of seeds smaller,which is the major factor causing explosive attenuation of seed precipitation.The mechanism of particles periodically explosive attenuating was also studied.