A hydrocyclone including: - a feed chamber , the feed chamber having: - an inner side wall , - a top wall located at an in use upper end of the inner side wall , - an open end located at an in use lower end of the inner side wall , and being opposite said top wall , the open end being of circular cross-section and having a central axis X-X, - an overflow outlet located at the top wall , and - an inlet port for delivering material to be separated to the feed chamber ; - a feed inlet zone located at the inner side wall of the feed chamber , the feed inlet zone being defined generally in the shape of a volute, wherein: - the distance from the inner side wall to the central axis X-X decreases with the progression of the volute around the inner side wall in a direction away from the inlet port ; and - the volute subtends an angle of greater than 270 angle degrees; - a generally conical separating chamber which extends from a first end at a region of relatively large cross-sectional area located adjacent the open end of the feed chamber , to a second end of relatively smaller cross sectional area; - a spigot which extends from the second end of the conical separating chamber , which in use provides an outlet for material exiting the hydrocyclone ; and - wherein the internal angle between an inner wall of the conical separating chamber and a line parallel to the central axis X-X is less than 8 angle degrees. - a feed chamber , the feed chamber having: - an inner side wall , - a top wall located at an in use upper end of the inner side wall , - an open end located at an in use lower end of the inner side wall , and being opposite said top wall , the open end being of circular cross-section and having a central axis X-X, - an overflow outlet located at the top wall , and - an inlet port for delivering material to be separated to the feed chamber ; - an inner side wall , - a top wall located at an in use upper end of the inner side wall , - an open end located at an in use lower end of the inner side wall , and being opposite said top wall , the open end being of circular cross-section and having a central axis X-X, - an overflow outlet located at the top wall , and - an inlet port for delivering material to be separated to the feed chamber ; - a feed inlet zone located at the inner side wall of the feed chamber , the feed inlet zone being defined generally in the shape of a volute, wherein: - the distance from the inner side wall to the central axis X-X decreases with the progression of the volute around the inner side wall in a direction away from the inlet port ; and - the volute subtends an angle of greater than 270 angle degrees; - the distance from the inner side wall to the central axis X-X decreases with the progression of the volute around the inner side wall in a direction away from the inlet port ; and - the volute subtends an angle of greater than 270 angle degrees; - a generally conical separating chamber which extends from a first end at a region of relatively large cross-sectional area located adjacent the open end of the feed chamber , to a second end of relatively smaller cross sectional area; - a spigot which extends from the second end of the conical separating chamber , which in use provides an outlet for material exiting the hydrocyclone ; and - wherein the internal angle between an inner wall of the conical separating chamber and a line parallel to the central axis X-X is less than 8 angle degrees. <EOS>