El principal mètode de producció industrial per produir metalls de terres rares mitjançant electròlisi de sal fosa. A la dècada de 1970, l'escala de les cèl·lules d'electròlisi de clorur de terres rares havia arribat als 50.000 amperes, amb una producció anual de milers de tones de metalls de terres rares, principalment metalls de terres rares mixtes de ceri, seguits de metalls ceri, lantà, praseodimi i neodimi. Segons el sistema d'electròlisi de sal fosa de terres rares, es pot dividir en dues categories: el sistema RCl3-KCl (NaCl), que electrolitza clorurs de terres rares; El segon és el sistema RF3 LiF BaF2 (CaF2), que electrolitza òxids de terres rares. L'electròlit per a l'electròlisi del sistema de clorur es prepara a partir del 35-50% de RCl3 i KCl anhidre. El contingut d'impureses (%) de les matèries primeres s'especifica com a Fe2O3<0.07, Ca<3, Th<0.03. The electrolysis temperature is higher than the melting point of the metal, and the temperature for producing mixed rare earth metals and cerium by electrolysis is 850-900 ℃; The temperature for electrolytic production of lanthanum is 900-930 ℃; The temperature for electrolytic production of praseodymium neodymium alloy is about 950 ℃. Using a molybdenum rod as the cathode, the current density is 3-5 A/cm2. Using graphite as the anode, the current density is less than 1 ampere/cm2. The slot voltage is 8-9 volts, and the pole spacing is adjustable. The metal yield is 80-90%, and the purity is 98-99.5%. The electrolysis method can also be used to produce alloys of rare earths, aluminum, magnesium, and even transition metals. There are two methods based on their working principles: ① using liquid metals such as aluminum or magnesium as cathodes, electrolyzing Y2O3 or YCl3 in YF3 LiF or YCl3 KCl systems to reduce and precipitate Y3+on the liquid aluminum or magnesium cathode, generating Y-Al or Y-Mg alloys with yttrium content of up to 20% and 48%, respectively; ② Co precipitation of electrolytic alloy components to produce Y-Al and Y-Mg alloys. When producing Y-Al alloy by electrolysis, an electrolyte with a molar ratio of LiF: YF3=1:4 is used. Under the process conditions of electrolysis temperature of 1025 ℃ and cathode current density of 0.6 A/cm2, a mixture of Al2O3 and Y2O3 with an electrolysis content of 14-17% is electrolyzed. Y3+and Al3+are reduced and precipitated together on the cathode to form Y-Al alloy. When producing Y-Mg alloy by electrolysis, the electrolyte of YCl3-MgCl2-KCl system is used for electrolysis at 900 ℃, and Y3+and Mg2+ions are jointly reduced and precipitated on the cathode to form Y-Mg alloy.