DE561173C - Process for the extraction of pure light metals and light metal alloys, especially pure aluminum - Google Patents

Description

Process for the extraction of pure light metals and light metal alloys, in particular of pure aluminum It is known to use technical grade aluminum to be refined by the fact that the primarily precipitated crystals of pure aluminum separated from the residual melt containing the impurities by filtration will. It was possible to produce very pure aluminum in this way, but it is does not go beyond the laboratory design. In addition to technical difficulties this procedure was transferred to large-scale operations, among others. the fact in the way that only several repetitions of the refining result in a substantial reduction the content of impurities.

It has also been proposed = the separation of the residual liquid melt of the primarily separated pure aluminum by being thrown off in a thermostat bring about. With this method, too, it must always be expected that part of the residual melt as a result of adhesion, among other things. on the pure aluminum crystals gets stuck, also with this method with regard to the - container material to expect difficulties. Metal equipment alloy with the treated Good, while ceramic bodies are subject to reduction. In the former case takes the aluminum to be cleaned, for example iron, in the latter possibly silicon on. It is also known to use an aluminum bath with multiple recrystallizations by submitting the liquid mother liquor by pouring off the granular Metal part is separated, which in turn after melting twice the is subjected to the same procedure. It has a ceiling to shut off the air found use of molten salt.

The invention differs from the known proposals in that the metal bath to be cleaned after the pure metal has solidified brought into intimate contact with a molten salt and that the pure metal then of the residual melt is separated.

In this way, the impurities can be washed off pure aluminum crystals solidified with the liquid cleaning salt in so perfect Way that the desired metal purity is achieved in one process stage.

As already mentioned, the same procedure is also used for aluminum alloys, in particular also those which, in addition to mixed crystals, primarily separated components included, applicable.

. The procedure is carried out, for example, as follows: Das zu cleaning and melted aluminum bath is after the pure aluminum crystals to the Have come to solidification, with a molten salt of suitable melting point and suitable specific gravity by-stirring-brought into intimate contact. To the Instead of stirring, other means, e.g. B. centrifugation, occur that convey an intimate contact of the metal bath with the molten salt.

In this way, the clinging to the pure aluminum crystals Impurities are washed away by the molten salt, so to speak, and there the individual Metal particles are surrounded by a shell of molten salt, the effect is achieved Separation is also maintained so that the pure metal is separated from the impurities containing residual melt can be separated. This separation can be known in Way, e.g. B. by hurling,. Squeezing, skimming, etc., take place. As a molten salt For example, there are mixtures. of barium-calcium halides with the addition of Potassium or sodium chloride, among others. in question.

Example i Refining of pure primary aluminum The process of the present refining became a primary aluminum of -99.1 0% Al; Subjected to 055% Fe and 0.35% Si.

After refining, the purity of the aluminum was up 99.78% increased and the impurities decreased to 0.08 Fe and 0.140/0, Si ".

Examples Refining of an aluminum-copper alloy The alloy contained 95.53% A1, 3.1 o / aCu, 0.8% Fe and 0.560% Si.

After refining, the aluminum content had risen to 96.53% and the impurities Fe and Si decreased to 0.18% and 0.24%, respectively. - The copper content had fallen from 3.10.10 to 3.05 per cent.

Claims (1)

PATENT CLAIM: Process for the extraction of pure light metals and light metal alloys, especially of pure aluminum, by fractionated Crystallization of the pure metal or: the pure mixed crystals from the to be cleaned Metal melt, characterized in that after the pure metal has solidified or the pure mixed crystals remove the liquid impurities by stirring with them be washed out of a molten salt and that the pure metal is removed from the remaining molten metal is separated.