in 1365 l deionized water is transferred to the pressurized vessel shortly after commencement of the calcium acetate addition the transfer is stopped and atorvastatin trihydrate hemi calcium salt seed prepared as described in u s pat no 5 969 156 which is herein incorporated by reference is introduced a seed slurry is prepared by charging 37 l deionised water and 13 kg methanol to a stainless steel make up delivery vessel the solvent mixture is agitated by rocking the vessel back and forth on its cradle 3 6 kg atorvastatin calcium seed crystals are then charged to the solvent mixture the contents of the delivery vessel are mixed by rocking until a seed slurry is formed sufficient pressure is applied to the make up delivery vessel so that its pressure is higher than that of the reaction vessel the make up delivery vessel is attached to the reaction vessel via a flexible hose and the seed slurry is charged rapidly over 2 to 3 minutes under pressure into the reaction vessel after the addition of the seed slurry the calcium acetate addition is immediately resumed to complete the calcium transfer the product cake is washed first with a methanol water solution followed by a water wash the wet product prepared in example 1 is loaded into a stainless steel continuous agitation pan dryer such as a guedu pan dryer a full vacuum of from u2212 0 80 to u2212 0 99 bar is applied the jacket of the dryer adjusted to 60 u00b0 c to 70 u00b0 c and the product dried with slow continuous agitation at approximately 1 rpm for at least 24 hours preferably for.