Method of making and recovering olefin polymer particles

A method for producing and recovering solid polyolefin particles in a particle form olefin polymerization process, comprising:

• directing a flowing liquid stream comprising liquid diluent, olefin monomer and catalyst for the polymerization and the resulting polyolefin particles under polymerizing heat and pressure conditions in the flow path through a continuous loop comprising a polymerization zone;
• directing a portion of said flowing liquid stream from said loop through a liquid cyclone separator for producing a concentrated slurry of a portion of said particles and a separate relatively clear liquid, while exchanging heat between said flowing liquid stream in said loop and said flowing liquid stream in said separator by immersing said cyclone separator in said flowing liquid stream in said loop at said polymerization zone for maintaining said flowing liquid stream within said separator at substantially the same temperature as said flowing liquid stream in said loop at said polymerization zone to continue said polymerizing conditions while said portion of said flowing liquid stream is passing through said separator;
• returning said relatively clear liquid to said polymerization zone;
• and
• directing said concentrated slurry to a place of recovery of said particles.