Magnesium from eutectics
So there are two threads that talked about the electrolytic reduction of magnesium: eutectic and alkalis but this is a patented and simple method.
It uses an eutectic mix of chloline chloride and magnesium chloride in DMF with an additive. Only thing I cannot figure out is if the other metal
chloride is needed. The patent is in chinese and I made my best effort to fix the machine tranlated version and to pretty it up. It is very
straightforward and easy to follow. But it mentions that you can either form magnesium or a magnesium alloy, so I guess if you choose no to
use the other chloride in the mix you get the pure magnesium, and otherwise the alloy?
Example 4:
A method for preparing metal magnesium using a new type of magnesium eutectic solvent electrolysis. The eutectic solvent was heated to 40 ° C, at
this temperature add 0.5% of the solvent mass of additive, stir to obtain a uniform and stable solution; the solution is deposited for 2.0 h under the
conditions of a nickel sheet electrode as a working electrode and a constant potential of -2.8V to obtain metallic magnesium or magnesium
alloy.
The eutectic solvent refers to adding choline chloride to the N,N-dimethylformamide solution at 40° C., stirring continuously until all is dissolved
to obtain amixed solution; and then adding Magnesium chloride hexahydrate and other metal chlorides are added to the mixed solution
at 40 ° C, stirring constantly,until all is dissolved; choline chloride is added in an amount of 10% of the mass of the N,N-dimethylformamide
solution. Theaddition amount of magnesium chloride hexahydrateis 70% of the mass of the mixed solution; the addition amount of other metal chlorides
is 50%of the mass of the mixed solution.
The other metal chloride is nickel chloride; the additive is boric acid
So you only have to mix DMF, chloline chloride, the magnesium and metal chloride and finally the additive at 40C in a fixed order and after every
addition you have to wait till it dissolves under stirring. Then turn up the current for an specified amount of time and you are done!
Other examples use different temperatures and additives, etc.
The patent is CN103173785 and the attached pdf is the translated version.
Attachment: A kind of novel magnesium eutectic solvent electrolysis to prepare metal magnesium.pdf (65kB)
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[Edited on 17-5-2021 by helzblack]
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