Uniformly pre-coating a filter screen with a mixture of

摘要

Uniformly pre-coating a filter screen with a mixture of finely divided anion and cation exchange resins The resin particles having a size in the range 60 - 400 mesh are slurried in water and a water-soluble, resinous polyelectrolyte is added to the slurry in an amount to prevent the resin particles from having a volume increase (over the volume of the particles in the dry state) of more than 550% whilst permitting a volume increase of more than 100%. The slurry is then passed through a filter screen to deposit the ion exchange resin particles on the screen. The polyelectrolyte prevents the excessive clumping which occurs in the mixt. of ion exchange resin particles and gives a precoat layer of uniform thickness on the filter screen.