Recycling of beryllium, manganese, and zirconium from secondary alloys by magnesium distillation in vacuum

Abstract

One of the methods for processing secondary magnesium raw materials containing rare refractory metals can be a distillation with the extraction of magnesium into condensate and the accumulation of rare metals in the distillation residue. The residue can be used as a master alloy for special alloys. To justify the possibility of this process, we calculated the boundaries of the vapor-liquid equilibrium fields for the regions of liquid solutions existence in the Mg – Be, Mg – Mn, and Mg – Zr systems at atmospheric pressure (101.33 kPa) and in vacuum (1.33 kPa). The value of the vacuum is due to the fact that a further increase in rarefaction will lead to the magnesium crystallization from the melt, and it will complicate the technology.We established that in the distillation process of magnesium removal from Mg – Be and Mg – Zr alloys, the vapor phase will be represented by more than 99.95 of magnesium. The presence of 0.45 mass.% Mn is possible in the Mg – Mn system at 1000 °C in thevapor phase – condensate . However, results of preliminary tests of the evaporation intensity established that the process conducted at 850-900 °C provides an acceptable evaporation rate of the volatile component (Mg) for technological conditions.Thus, we confirmed the possibility of the proposed method to process secondary light alloys containing beryllium, manganese, and zirconium, which can be involved in the main process intended to produce special alloys in the form of a master alloy with magnesium.