Separator for a mixture of a suspension and coarse heavy particles

A separator for separating a mixture into a light fraction consisting of a suspension, such as a cellulose pulp suspension, and a heavy fraction of coarse particles, the separator comprising means forming a first separation chamber having a first inlet for said mixture, a first outlet for the light fraction, and an outlet for an intermediate fraction enriched in coarse particles, said means also forming a second separation chamber having a second inlet, a second outlet for a light return fraction, and an outlet for separated heavy fraction, said outlet for an intermediate fraction being connected to the second inlet and leading from a first zone in the first separation chamber, said zone having a higher pressure than a second zone connected to the second outlet, said second zone communicating with the first separating chamber, the first and second separating chambers communicating to form a circuit, said second outlet for a light return fraction being located between an inlet region in said second separation chamber and an outlet region in said first separation chamber, the separator including stationary means for maintaining in said inlet region a pressure sufficiently higher than the pressure in said outlet region to induce flow of said light return fraction from said second chamber to said first chamber by way of said second outlet, said inlet region and outlet region being free of any moving part.