Drilling of stub holes in prebake anodes

Abstract

Stub holes may be a troublesome part in the production of anodes. Tension and cracks can be created around the stub hole. Vibrating the stub holes often introduces limitations for the optimisation of the production process. Stub holes oriented towards the cassette wall during baking will be filled with packing material. This requires that the stub holes need to be thoroughly cleaned after baking. Stub holes that are oriented away from the cassette walls are unprotected during the baking process. This may lead to an increased rejection rate or additional costs to protect the stub holes. The paper will present four years of experience with drilling of stub holes in baked anodes. This technology allows for the drilling of different stub hole designs, and the paper will summarise the results from trials where three different designs are tested in the same reduction cell.