Physical Simulation on Mixing Uniformity in Seed Precipitation T ank

摘要

The suspension and dispersion of Al(OH)3 particles in seedrnprecipitation tank, which may affect the quality and output ofrnalumina besides the deposit on the bottom of the tank, is one ofrnthe key steps in Bayer process. In order to solve these problems,rnthe solids concentration profiles of Al(OH)3 particles wererninvestigated by cold water experiments under simulatedrnindustrial conditions. The results showed that, the mixingrnuniformity in the whole tank improved with the increase ofrnimpeller off-bottom clearance when used the impeller of smallrndiameter (D / T ≤ 0.6), and it deteriorated when enlarged thernimpeller (D / T = 0.65 ～ 0.7). The mixing effects can bernimproved by increasing the impeller diameter and stirring speed,rnmeanwhile the influence of impeller off-bottom clearance wasrnweakened. But the impeller diameter and stirring speed shouldrnbe controlled in appropriate ranges for the consideration ofrnpower consumption and mixing efficiency.