provided is a fused salt electrolysis process for preparing neodymium or a neodymium alloy , especially a neodymium / iron alloy , which has a high purity and a reduced carbon content , at a low cost , a high current efficiency , and a high productivity . according to this fused salt electrolysis process , by collecting the formed neodymium or neodymium alloy at the bottom of the bath and incorporating oxygen gas in the atmosphere above the bath , powdery carbon generated from the carbon electrodes is removed by oxidation and consumption and the electrolysis bath is stabilized . furthermore , by using a plate - shaped electrode at least for the anode , the critical current density is increased and neodymium or a neodymium alloy can be formed at a high current density and a high current efficiency .