GB825872A - Improvements in or relating to the electrolytic production of magnesium - Google Patents

Abstract

825,872. Electrolytic production of magnesium. EGAMI, I. June 20, 1956 [June 20, 1955], No. 19132/56. Class 41. In a method for the electrolytic production of magnesium by the electrolysis of a fused mixture comprising magnesium chloride and alkali metal and/or alkaline earth metal halides, the anode comprises a paste-like mixture of a carbonaceous substance and a magnesium compound capable of reacting with the chlorine found in the electrolysis, the said paste-like mixture being surrounded by a metal shell and both the paste-like mixture and the metal shell being built up from above as the anode is consumed from below by the electrolytic process. Specified magnesium compounds capable of reacting with chlorine are magnesium oxide, roasted magnesite and magnesium hydroxide. Specified carbonaceous substances are pitch, tar, pitch oil, graphite, powdered coke and powdered charcoal. When solid substances only are used for the material of the paste a proportion of oil may be added to produce the consistency desired. As shown (Figs. 2 and 3), an anode assembly comprises an anode shell in the form of a box 1, of thin sheet iron, aluminium, magnesium or alloys thereof, an outer frame 2, consisting of side members detachably bolted together of a material which is not consumed in the electrolytic process and a lattice 3 (Fig. 5), consisting of a plurality of metal bands riveted together and arranged within the box 1. The anode assembly, the box being filled with anode paste, is suspended from a supporting frame 5 (Fig. 2) into an electrolytic bath' 4 by means of pulleys 6, ropes 7 and hangers 8. The cathode comprises two iron comb electrodes 9 suspended into the electrolytic bath (Fig. 2). The anode paste consists of roasted magnesite and pitch oil. The electrolytic bath is charged with a mixture of magnesium chloride and sodium chloride and a small amount of calcium fluoride. In the course of operation the anode paste, together with the box and lattice work are gradually consumed from below. The paste is replenished from above; the assembly is lowered gradually by adjusting the hanger 8 (Fig. 2); the lowest strip of the frame assembly 2 is detached and then connected again above to the anode assembly; and the lattice 3 is at intervals extended upwards by connecting a new lattice work thereto. The box is built up from above by placing box sections of the appropriate dimensions on top of the uppermost part of the box. The upper and lower edges of the box sections may be adapted to engage by means of half-lap joints. Metallic magnesium is liberated at the cathode.