  COSINE-200 is the next phase of the ongoing COSINE-100 experiment. The main
purpose of the experiment is the performance of an unambiguous verification of
the annual modulation signals observed by the DAMA experiment. The success of
the experiment critically depends on the production of a 200 kg array of
ultra-pure NaI(Tl) crystal detectors that have lower backgrounds than the DAMA
crystals. The purification of raw powder is the initial but important step
toward the production of ultra-pure NaI(Tl) detectors. We have already
demonstrated that fractional recrystallization from water solutions is an
effective method for the removal of the problematic K and Pb elements. For the
mass production of purified powder, a clean facility for the fractional
recrystallization had been constructed at the Institute for Basic Science
(IBS), Korea. Here, we report the design of the purification process, material
recovery, and performance of the NaI powder purification facility.
