Use of an additive for improving the flowability of fines and their reintroduction into a continuous gas-phase (co-) polymerisation of olefins reactor

Procedure for the (co) polymerization of olefins in the gas phase in the presence of a catalyst in a reactor fluidized bed system or sub fluidized bed, comprising the reactor a recycle line connecting the top of the reactor to its bottom and a cyclone being connected to the cyclone reactor top and the cyclone outlet being connected back to the reactor at a lower height, where the polymer particles being formed are maintained in a fluidized state or sub fluidised by a gaseous reaction mixture traveling as an ascending stream through the reactor, the gas mixture leaving the top of the fluidized bed reactor or sub-fluidised bed is recycled to the base of the reactor through the recycle line and at least part or preferably all of said gas mixture leaving the top of the fluidized bed reactor or sub-fluidised bed is passed through at least one cyclone in order to separate the gas from the particles fine, and the fine particles are recovered from the bottom of the cyclone and recycled back to the reactor, wherein an enhancing additive flowability in a point between the top of the reactor and the cyclone is added.