Patent ID: 7504016

Claim:
A method for controlling additions of powder materials into an electrolytic cell designed for the production of aluminium by fused bath electrolysis and provided with at least one boring device comprising an actuator and a crustbreaker, the actuator comprising a piston connected to a piston rod, the piston rod being connected to the crustbreaker, said cell containing a liquid electrolyte bath and being operated such that an alumina and solidified bath crust is formed above the liquid electrolyte bath, the method comprising: generating an electrical signal to provoke lowering of the crustbreaker using the actuator, measuring the moment at which the crustbreaker reaches a predetermined low position, using at least one position detector capable of detecting a position of a component of the actuator selected from the group consisting of the piston and the piston rod, determining the value of at least one powder material feed operation indicator, based on the measured moment, using a function, using at least one operation criterion and the value of the operation indicator to determine whether an operation is abnormal, if the operation is not considered to be abnormal, maintaining a determined procedure for feeding a powder material into the bath through an opening created by the crustbreaker, and if operation is considered to be abnormal, triggering at least one correction procedure that can correct the abnormal operation.