Aluminium monohalide process of producing and refining aluminium

Abstract

It can be said from the present available reports of foreign countries on studies on monovalent aluminium that although halides are used on producing and refining aluminium and there are some patents for practical apparatus, it has not risen yet above the experimental stage. Even among the theoretical reports on this subject, there is hardly any that makes clear the real characteristics and properties of monovalent aluminium.Therefore at first the equilibrium and reaction velocity, of the following reaction in which monovalent aluminium is produced were studied: AlCl3+2Al_??_3AlClThen the utilization of this reation for obtaining pure aluminium from impure aluminium and alumina ores was studied as follows:(1) In the equilibrium in which a monovalent aluminium compound in the form of AlCl is produced between liquidus aluminium (I) and gaseous aluminium chloride, (II) the equilibrium constant was measured and moreover the reactivity of (I) and (II) was observed under reduced pressure.(2) The reactions when gaseous AlCl3 is introduced to a mixture of Al2O3 and C are as follows. (Al2O3+3C+Cl2→2AlCl+3CO)…(1)' Al2O3+3C+AlCl3→3AlCl+3CO…(1) 3AlCl→2Al+AlCl3…(2)From calculating the variation of the free energy it was found that this reaction of the method of obtaining metallic Al by decomposing the aluminium monochloride produced by reduction and at the same time chlorination of the raw material containing alumina is carried out at about 1400°C.Pure aluminium can only be obtained by the reaction of Al2O3+3C+AlCl3.(3) However, when SiO2 is present in the material of the vessel in which the reactions take place, besides the above reactions (1) and (2), other reactions of SiO2(s) +C(s)+AlCl3(g) group, and Al+SiO2→Al2O3+Si occur together, and a mixture of SiO2-Si-Al2O3 is found on the cooling pipes. The formation mechanism of this reaction was also studied.(4) Therefore, this method in which aluminium ores, such as kaolinite or bauxite, containing SiO2 is reduced to Al and at the same time seperated from the impurities proved to be impractical because the reaction, (SiO2+C+AlCl3), takes place to considerable extent at lower temperatures than the reaction, (Al2O3+C+AlCl3), does