The Centrifugal Separation of NaOH·3.5H₂O Crystals Obtained from the Secondary Refrigerant Freezing Process

Abstract

The dehydration experiments of the NaOH·3.5H₂O crystals obtained from the continuously-well-stirred crystallizer by employing the secondary refrigerant freezing process were carried out. And for these experiments a conturbex type centrifuge was used, and the permeability of the crystal bed was also measured.
From these experiments, the apparent residual equilibrium saturation of the solid product was found to be zero. The experimental equation of saturation S was given from the surface mean size of crystal l, the centrifugal effect Z and the production rate P as follows: S=0.05 (l_av²Z/P) ^-0.563.
The operating diagram of crystallization-dehydration was obtained from the experimental equation about saturation and from the crystallization diagram reported in the previous in consideration of the size distribution function of crystals produced from the well-stirred crystallizer.