GB923344A - Improvements in or relating to electrodes - Google Patents

Abstract

923,344. Fused-electrolyte cells. E. I. DU PONT DE NEMOURS & CO. Dec. 22, 1959, No. 43536/59. Class 41. A composite graphite electrode for use in an anode in a fused-salt electrolytic cell comprises at least three elongated graphite pieces arranged in a row (side by side) and adapted to be joined in operation to a common source of electricity, the respective cross-sectional areas in planes normal to the longitudinal axes and the respective specific electrical resistances of the pieces being such that the current density over the electrolysis zone is substantially constant, the electrode having a substantially rectangular transverse cross-section on planes normal to the plane defined by the longitudinal axes. The specific resistances of the pieces may be equal, in which case the ratio of (a) the crosssectional area of each piece in a plane normal to its longitudinal axis to (b), the length of its " electrolytic perimeter " is equal for all the pieces, i.e.: the " electrolytic perimeter " being the perimeter bounding the corresponding cross-sectional area and facing the cathode 3. This ensures equal current densities for all the electrodes. The areas are adjusted by forming wells 4 of any cross-sectional shape which may communicate with the exterior by slots 5, the electrodes abutting at their bottom ends which contact a metal bus-bar. The quadrants 1, 2 formed by the slots 5 must satisfy the equation A B C above, i.e. - = - = -, and the radius of the a b c wells 4 and the position of the slots 5 in the end pieces are worked out mathematically in the Specification. The specific resistance of the middle piece may be different to that of the end pieces, the values of the cross-sectional areas being adjusted accordingly, e.g. the areas may be equal.