Abstract: In a multistage countercurrent crystallization apparatus for multistage crystallization by adiabatic recrystallization and extractive washing comprising a vertical column containing a feed line, a waste material discharge, a purified product discharge, a crystallization zone or chamber at one end and a melter or dissolver at the other end, said vertical column containing a crystallizing liquid, a number of perforated plates subdividing said column into multistages, substantially spherical bodies contacting said perforated plates of a size larger than said perforations and designed to cooperate with the perforations of said perforated plates while in motion with respect to said perforated plates, means for vibrating said perforated plates whereby said substantially spherical bodies vehemently vibrate against said perforated plates, the improvement consisting essentially of reciprocating means to move said crystallizing liquid slowly and periodically with respect to said perforated plates in said column where s