Abstract: The invention relates to a metal boride precursor mixture comprising a metal oxide and a boric oxide combined in such a manner so as to produce intimately linked clusters wherein the boric oxide is found within the metal oxide. Furthermore, the invention discloses a carbon composite material made with the metal boride precursor mixture and a carbonaceous component. Finally, the invention also teaches the process for preparing the metal boride precursor mixture comprising steps of providing a metal oxide and a boron oxide, mechanically mixing the metal oxide and the boron oxide at a temperature that liquefies the boron oxide and may impregnate the metal oxide to produce an intimately linked cluster of metal oxide and boric oxide.

Abstract: In a process for the production of aluminium a molten alumina slag, containing combined carbon is circulated through one or more alternately arranged relatively low temperature zones where carbon is added to increase the combined carbon content of the slag by reaction with the alumina slag and high temperature zones where aluminium metal is released by reaction of aluminium carbide and alumina in the slag with consequent depletion of the combined carbon content. Alumina is supplied to the slag at one or more locations. The energy to drive the reactions is preferably supplied by resistance heating of the slag particularly in transit from a low temperature zone to a high temperature zone although usually additional energy is supplied to the slag in the return from a high temperature zone to the next low temperature zone.In most instances the aluminium-liberating reaction is carried out in an upwardly inclined passage and the gas evolved is employed to achieve the circulatory movement of the slag.