Process for supplying catalyst to a polymerization reactor

A method for feeding metallocene catalyst slurry to an olefin polymerization loop reactor using a positive displacement device comprising a first chamber and a second chamber, each chamber having an inlet and an outlet and each chamber comprising a ball arranged between walls of said chamber, said chambers being operably connected to each other by a pump chamber, comprising the step of activating the pump, thereby:

• a) charging the positive displacement device with catalyst slurry into the pump chamber by aspirating the catalyst slurry between the ball and the wall of the first chamber;
• and
• b) discharging the catalyst slurry into the loop reactor by displacing the catalyst slurry between the ball and the wall of the second chamber, wherein, a difference between a diameter of each ball and a diameter of each chamber is between 5 to 200 times an average particle size (d50) of said metallocene catalyst.