The invention relates to a high-concentration mixer (1) for producing a suspension (2), comprising a stationary container (3) and an agitator (8) arranged in the container axis (7), which agitator is connected to a motor via a flange (9) provided in the region of the container bottom (4), which motor is designed for rotationally driving the agitator (8) for mixing the suspension (2) provided in the container (3), wherein the agitator (8) has helical coils (11) which bring about a vertical downward flow (12) of the suspension (2) in the centre of the container (3) and a vertical upward flow (13) of the suspension (2) in the region of the container wall, wherein the flange (9) comprises at least one blade (15) provided on its circumference, which is designed for wiping the suspension (2) from the container (3) and for supporting the vertical upward flow (13) of the suspension (2) in the region of the container wall.