Preparation of Magnesium-Rare Earth Master Alloy Using Electrowinning Method with Subsidence Cathode

Abstract

A new series of magnesium-rare earth master alloys have been developed by the electrowinning method with subsidence cathode in the KCl•NaCl-RECl3 system. The electrolysis conditions were studied. Experimental results showed that the optimum for electrolyte at 850oC and 10~20wt% RECl3 content in the molten salt system. The current efficiency of electrolyte increased with increasing the rare earth content and reach the maximum at the content of 20% RECl3. The current efficiency gradually decreased with increasing cathode current density. The component of master-alloys was analyzed using ICP-MS and chemical method. A series of magnesium-rare earth master-alloy, Mg-Y, Mg-Nd, Mg-Ce, Mg-La, Mg-Nd-rich and Mg-LPC were successfully prepared and the content of rare earth is adjustable between 5 – 20%.

Electrochemical Behavior of Neodymium and Formation of Mg–Nd Alloys in Molten Chlorides

“…Although reduction behavior of Nd­(III) and formation of Mg–Nd alloys have been investigated in several studies, − the electrochemical behavior of Nd­(III) and its coreduction with Mg­(II) in molten NaCl–KCl eutectic, especially aimed at recycling neodymium from NdFeB scrap, have not been reported in the current literatures . As part of a series of fundamental studies for developing a total recycling route, the present article reports the electrochemical behavior of Nd­(III) and production of Mg–Nd alloys in eutectic NaCl–KCl melts with an emphasis on the alloy formation mechanism, which is the necessary information for developing a novel NdFeB recycling technology via molten salt chlorination and electrolysis.…”

“…According to our previous work, RE metals (Nd, Pr, and Dy) in NdFeB magnet scrap can be extracted by the selective chlorination of molten MgCl 2 and transform into RE chlorides . Because the standard electrode potential of RE is relatively close to that of Mg, − NdCl 3 in the obtained molten salts can be recovered directly as Mg–Nd-based alloys, which can be used as the master alloys or to prepare pure RE and Mg metals via evaporation . To date, molten salts electrolysis is still the main method for industrial production of pure aluminum, magnesium, and most of the rare earth metals and has also been proposed to produce Mg–RE and Mg–Li–RE alloys. − Currently, most Mg–RE alloy is prepared via vacuum melting using pure Mg and RE metals as raw materials either in the laboratory or in industry .…”