PROCESS AND APPARATUS FOR VACUUM DISTILLATION OF HIGH-PURITY MAGNESIUM

摘要

A starting material 2 in the form of a magnesium-containing metal melt is present together with the upper region 32 of a condensation vessel 3 in the upper region 11 of a retort 1 heated by the external heating element 5, wherein the steam produced according to the arrows 91, according to arrow 92, enters the upper region 32 of the condensation vessel 3 through the opening 31 below the cover 4 which provides protection from unwanted ingress of contaminated magnesium melt, wherein said steam condenses in the lower region 12 of the retort which is heated by a second heating element 51, below the line 8 corresponding to the melting point isotherm of magnesium, to give the high-purity magnesium melt 21 in the lower region 33 of the condensation vessel 3. By opening a barrier unit 6, the interior of the retort 1 can be connected temporarily to the supply chamber 13, and also via a line 73 and a valve 72 to a vacuum pump 73, via a further line 74 to a pressure measuring instrument 75, and via a third line 76, via a valve 77 and a pressure and/or flow regulator 77 to an inert gas source 79.

主权项

1. A process for producing high-purity magnesium by distillation at reduced pressure, characterised in that a starting material in the form of a magnesium-containing metal melt with the upper region of a crucible-shaped condensation vessel, which is formed from a material inert with respect to magnesium and which has an opening that provides protection against ingress of contaminated refluxing magnesium melt by a cover inert with respect to magnesium and that allows the entry of magnesium steam, in the upper part of a vacuum-tight retort which can be externally heated to different temperatures by one or more heating elements in the horizontal direction and which is made of a material that is largely inert with respect to magnesium or at least does not release impurities capable of evaporation is at a temperature above the melting point and in the immediate region of the magnesium-containing melt and the opening of the crucible-shaped condensation vessel is above the boiling point of magnesium, wherein the lower region of the crucible-shaped condensation vessel in a tapering region of the retort, closely surrounding the lower region of said condensation vessel, is in a temperature gradient between the boiling point and melting point of magnesium, and in that the retort can be connected at least temporarily via a barrier unit to a supply chamber, which in turn can be connected via lines and a valve to a vacuum pump, via a further line to a vacuum measuring instrument, and via a third line and a valve to an inert gas source, wherein the pressure within the retort during the distillation process is held in a setpoint pressure range, that is to say is reduced on the one hand to such an extent that the boiling point of the magnesium reduces to a temperature that is thermally sustainable for the material of the retort and on the other hand is held by selective addition of inert gas at a minimum value, at which the boiling point of the pure magnesium melt present in the lower region of the crucible-like condensation vessel is not exceeded.