无搅拌氢氧化铝晶种分解槽中的固相分散研究（英文）

Solid Dispersion in an Unstirred Seeded Precipitation Tank for Gibbsite Crystallization

在拜耳法生产氧化铝的过程中,为探索氢氧化铝结晶过程中的节能措施,采用工业试验和计算流体力学的方法对无搅拌氢氧化铝晶种分解槽中的固相分散规律进行了研究.试验结果表明,在正常工业流速条件下,无搅拌分解槽的大部分区域即从槽底至高度为25 m的范围内的固相质量含量差较小,仅为48.19 g/L,而在顶部的相对较小的区域即离槽面5 m范围内的固相质量含量差较大,达到149.66 g/L.因此,在正常工业流速条件下,无搅拌的分解槽中的固相分散不会完全向底部聚集.计算机模拟的结果也很好地揭示了这一固相分散规律,同时发现,随着槽内流速的增加,顶部较大固相质量含量差的区域逐渐收缩并向槽面靠拢,这意味着整个槽内的固相分布更加趋于一致.

In order to explore the energy saving measures in gibbsite crystallization process for alumina production by Bayer method, industrial experiment and computational fluid dynamics method are carried out to investigate the solid dispersion in an unstirred seed precipitation tank of Gibbsite. The experimental results show that there is little difference in solid mass concentration： only 48.19 g/L is found in the range between the bottom and the height position of 25 m, which is the most zone of the tank, and there is a somewhat large difference in the top 5 meters＇ zone that is about 149.66 g/L. Therefore, without stirring, solid content will not concentrate to the tank bottom completely under the condition of normal work flow. The simulation results also aid to reveal the same characteristics of solid dispersion in the unstirred precipitation tank. It is found that, with the inlet velocity increases, the difference of solid mass concentration in the top zone shrinks to near the tank surface, which makes the solid dispersion in the whole tank uniform much more.