PURIFYING METHOD OF POLYPROPYLENE AND APPARATUS

PURPOSE:To purify the titled polymer in a very simple apparatus, by washing a formed polymer with a washing liquid consisting of a monomer as a principal component at such a rising rate as to form an interface between a slurry and the washing liquid, and using partition plates of specific dimension in the vertical direction of a countercurrent washing column. CONSTITUTION:Propylene as a medium is solely mass polymerized or copolymerized with another alpha-olefin, and a slurry containing the resultant polypropylene is introduced from a nozzle 1 into a long countercurrent washing column having a part of =10X(cross-sectional area surrounded by the partition plates) length in the vertical direction. Propylene for washing is then introduced from a nozzle 3 to control the rising rate under such conditions as to form an interface between the slurry and the washing liquid. The slurry is then washed in the countercurrent manner to discharge the washing liquid from a discharging nozzle 2 and the slurry from a discharging nozzle 4 respectively. Thus, the formed polymer is washed and purified.