Abstract: A powder feeding apparatus comprising a powder storage receptacle for defining a space to hold a powder and a metering chamber disposed beneath the holding space for receiving the powder flowing from the holding space. The powder is metered in the metering chamber and discharged. The apparatus includes a metering section having a metering space for defining the metering chamber and a metering adjusting member disposed slidably in the metering space of the metering section. The volume of the metering chamber is adjusted by sliding the metering adjustment member.

Abstract: A process for producing a propylene polymer or copolymer which comprises polymerizing (a) propylene or (b) a mixture of propylene and another unsaturated hydrocarbon monomer in liquid propylene in the presence of a catalyst system of(A) a specified titanium trichloride composition obtained by reducing titanium tetrachloride with an organoaluminum compound and activating the product;(B) an organoaluminum compound having the general formulaR.sub.2 AlXwherein R represents an alkyl group or an aralkyl group, each containing up to 18 carbon atoms, and X represents a halogen atom; and(C) an unsaturated carboxylic acid ester; while adjusting the amount of the polymer produced to at least 8,000 g per gram of the titanium trichloride composition.

Abstract: A process for producing a homopolymer of propylene or a copolymer of propylene which comprises polymerizing propylene or a mixture of propylene and another unsaturated hydrocarbon monomer such as ethylene in liquid propylene, in the presence of a catalyst system consisting essentially of (a) an activated titanium compound obtained by reducing titanium tetrachloride with an organic aluminum compound and activating the resulting titanium compound and (b) an organic aluminum compound to produce a polymer slurry, introducing the polymer slurry into an upper part of a counter-current washing zone, such as a washing tower, and counter-currently contacting the polymer slurry with liquid propylene which is introduced into a lower part of the washing zone, whereby the polymer and catalyst residues dissolved in the polymer slurry are removed.

Abstract: A process for polymerizing .alpha.-olefins in a solvent under conditions such that the polymer formed grows as particles, in which the process comprises reusing a greater part of the solvent used for the polymerization by recycling the solvent to the polymerization zone without carrying out any purification treatment.