Electrical contact for cathode bar in groove in carbon block - esp. in electrolysis cell used for winning aluminium from molten cryolite electrolyte

摘要

A groove is formed in a carbon block and extends over the entire length of the block. Starting from the base of the groove, both its side walls taper outwards, and then form a shoulder. Both shoulders are followed by parallel groove walls extending to the surface of the block. The space between the groove walls and a cathode bar placed in the groove is filled with cast iron which completely surrounds the cathode bar. The height(h) of the taper is pref. 40-70% of the total height(t) of the groove. The angle(alpha) of the taper is pref. 3-15 deg. w.r.t. the vertical. A good electrical contact is obtd. between the cathode bar and the carbon block without the risk of cracks occurring in the block when it and the bar are heated to ca. 940-970 deg.C., i.e. the operating temp. of the electrolysis cell.