The Impact of Anode Nails on the Stub to Carbon Electrical Contact Resistance of Anode Assemblies with Simulated Corroded Stubs

The solidification shrinkage of cast iron causes low contact pressure and high contact resistance in the stub to carbon connection. The use of steel anode nails to bridge the shrinkage gap has previously been demonstrated to reduce contact resistance with full diameter stubs. New laboratory testing with reduced diameter stubs to simulate stub corrosion, and with anode nails, demonstrates the higher electrical resistances that result from the wider iron shrinkage gap, and how the anode nails can consistently provide a lower contact resistance over the full anode cycle. This lower and more consistent resistance between hot vs. cold stubs, and new vs. worn stubs can be used to predict a reduced variation in current distribution between anodes in a reduction cell.