Abstract: The carbon anodes of aluminum reduction cells are suspended on anode rods. The lower part of these rods viz., the anode pins or stubs can be anchored in the carbon anode by pouring cast iron into suitably shaped anode pin or stub holes which are at least partially undercut at the sides.A horizontal layer of cast iron at least some millimeters thick is formed between the floor of the pin or stub holes and the lower face of the anode pins or stubs.The cast iron poured into the spaces around the anode pins or stubs heats these to over 400.degree. C. The mass of the cast iron poured in is smaller than the mass of the lower part of the anode pin or stub to be enclosed.

Abstract: In order to control a crust breaker featuring a chisel which can be moved up and down to break the crust on a fused salt electrolytic cell, an electric impedance measuring circuit comprising signal generator and registering instrument is connected between the chisel and the molten electrolyte. As such the generator is preferably in the form of an alternating signal generator, and DC signals, such as operating parameters of the cell and the voltage between the anodes and the cathode, are excluded from the impedance measuring circuit by means of DC neutralizing capacitors.

Abstract: Method of protection of electrically conducting parts in fluoride melts through which direct current flows in the electrolysis of aluminum oxide, comprising applying such an electrical potential to said parts that the direct current flowing through the fluoride melt cannot emerge from the parts at any place within the fluoride melt.