Abstract
Generally speaking, it is not easy to produce hard, cubical, large-sized salt crystals in the mother liquor concentration process. We studied the characteristics of salt crystallization in this process using Toyokura's equation for the crystal nucleation rate and the crystal growth rate, taking microscopic photographs, and measuring crystal compressive strength. Under the conditions within the range of 0.005-0.020 m3/m3/h of production rate and of circa 33°Bé of liquid density in the evaporating chamber, grown crystals converged to the maximum size (e. g., 500μm) within 6 hours in that chamber. It was confirmed that maximum crystal size became smaller with higher liquid density. This limitation of crystal growth is considered to be caused by impurities. The salt obtained in this process was found to be weaker in compressive strength and to contain more coagulated or irregularly shaped crystals compared to common evaporated salt.
