Collection unit (100), of bucket scoop type, used in a cell for producing aluminium, comprising: a) a means of attachment to a mobile support (5'); b) a connection (52, 52') activated by a first actuator (50) that moves relative to said mobile support in a vertical direction; c) a frame (110) firmly attached to said connection; d) at least one articulated bucket (120a, 120b) that pivots about an axis (115a, 115b) mounted on said frame, that has a blade (128a, 128b) and that pivots about said substantially horizontal axis. Said first actuator (50) is connected to a programmable control system capable of determining the altitude of said axis and the difference in altitude between said blade and said axis, defining the vertical displacement to be imposed upon said collection unit, defining and transmitting to said first actuator the appropriate control flow in order to impose said vertical displacement. The control flow may be a control current transmitted by a speed controller to an electric motor or a flow of oil feeding the chamber of a hydraulic cylinder, controlled by a servo valve.