Spiral separators

Claim 1

A SPIRAL SEPARATOR FOR CLASSIFYING SOLID PARTICLES INTO COARSE AND FINE PARTICLES BY MEANS OF A SUSPENSION MEDIUM, COMPRISING A FREE FLAT SUBSTANTIALLY CYLINDRICAL AND ROTATIONALLY SYMMETRICAL SEPARATING CHAMBER, SAID SEPARATING CHAMBER BEING LIMITED AT ITS CIRCUMFERENCE BY A PLURALITY OF BLADES DISPOSED IN A ROTATIONALLY SYMMERTICAL STATIONARY ARRAY FOR GIVING SAID SUSPENSION MEDIUM MOVEMENT IN A SPIRAL DIRECTION, SAID CHAMBER BEING LIMITED AT ITS ENDS BY SUBSTANTIALLY PLANE ROTATABLE END WALLS TRANSVERSE OF THE AXIS OF SAID ARRAY, ONE OF SAID END WALLS BEING OF SMALLER DIAMETER THAN THE INNER DIAMETER OF SAID ARRAY, THE PERIPHERY OF SAID WALL DEFINING THE INNER EDGE OF AN ANNULAR INLET APERTURE FOR THE MATERIAL TO BE CLASSIFIED, MEANS FOR SUPPLYING THE MATERIAL TO BE CLASSIFIED TO SAID INLET APERTURE, A CHAMBER FOR RECEIVING THE SEPARATED COARSE PARTICLES LOCATED CLOSE TO THE OTHER ROTATING END WALL AND COMMUNICATING WITH AN ANNULAR OUTLET APERTURE FOR THE COARSE PARTICLES LOCATED BETWEEN THE PERIPHERY OF SAID OTHER END WALL AND SAID ARRAY, ONE OF THE END WALLS HAVING A CENTRAL OUTLET APERTURE FOR THE SUSPENSION MEDIUM CARRYING THE FINE PARTICLES, AND MEANS FOR CAUSING A SUSPENSION MEDIUM TO FLOW THROUGH SAID ARRAY OF BLADES INTO THE SEPARATING CHAMBER.