Synthesis of magnesium-zinc-yttrium master alloy

Abstract

The research investigates the process of synthesis of magnesium master alloy with zinc and yttrium. Based on the analysis of state diagrams and requirements for fluxes for smelting of magnesium alloys, the composition of the saline mixture was chosen. X-ray phase analysis of the molten salt mixture showed that during the melting process, yttrium fluoride partially interacted with sodium and potassium chlorides, forming complex salts: Na 1.5 Y 2.5 F 9 , NaYF 4 , Na 5 Y 9 F 32 , and KY 7 F 22 , which are the source for yttrium recovery. Differential thermal analysis (DTA) determined the temperature ranges and values of thermal effects of melting and crystallization of a mixture of the KCl-NaCl-CaCl 2 -YF 3 salt in the recovery of yttrium compounds by a magnesium-zinc alloy. It was determined that interaction within the system begins at a temperature equal to the initial melting point of zinc, and occurs in the range from 415°C to 672°C. As a result of series of experimental meltings, the basic laws of the synthesis of magnesium-zinc-yttrium master alloys from the selected technological salt mixture, as well as the main factors of the metallothermic process, affecting the degree of yttrium reduction were revealed. The metallographic study of the alloys obtained showed that the samples consisted of solid solutions of Mg x Zn y and intermetallic compounds of Mg x Y y Zn z , which were located along the boundaries of dendritic cells. The proposed method of recovery of yttrium fluoride from the chloride melt allows extracting up to 97.2 % of yttrium.

Concentration of Rare Earth Elements (Sc, Y, La, Ce, Nd, Sm) in Bauxite Residue (Red Mud) Obtained by Water and Alkali Leaching of Bauxite Sintering Dust

“…The volumes of production/consumption of rare and rare-earth metals, which are critical for modern industries, are steadily increasing [1][2][3][4]. In this group of metals-scandium, yttrium, lanthanum, and lanthanides-scandium is the most scarce and commercially attractive one.…”

Synthesis of Mg–Zn–Nd Master Alloy in Metallothermic Reduction of Neodymium from Fluoride–Chloride Melt

“…In the first series of experiments, the temperature effect on the degree of neodymium extraction was studied during experimental research on the neodymium reduction from a fluoride-chloride melt in a shaft electric furnace. In this case, in order to reduce the temperature for the synthesis of the ternary master alloy was taken the constant value of the Mg:Zn ratio equal to 1:2 [31]. As a result of processing the obtained data, the dependences of the degree of extraction of neodymium on the residence time at temperatures of 550, 600, 650, 700 • C were assessed (Figure 3).…”

An Interval-Simplex Approach to Determine Technological Parameters from Experimental Data

“…The indicator concentration at the outlet of the reactors cascade for various periods of time is introduced in Table 1. We use the equation to process the experimental data (29). The experimental data are represented on the logarithmic scale, lnS c = ϕ(lnS τ ).…”

“…To determine the mathematical model parameters for a continuous reactor, it is first necessary to consider the RTD of the material in the apparatus, which will ultimately improve the economic efficiency of the process under consideration. Information about RTD in the apparatus enables evaluation of the efficiency of the apparatus itself, which determines the proportion of the apparatus volume occupied by particles within a given time interval [28][29][30].…”