Experimental investigation of the phase relations in the SiO2-Dy2O3-CaO ternary system

Abstract

This paper reports on the experimental investigation of the phase relations in the CaO-SiO2-Dy2O3 system. CaO-SiO2-Dy2O3 slags were equilibrated at 1773 and 1873 K for 24 h in Ar and then quenched in water to determine the phase relations of the system. The composition of the equilibrated phases was measured by EPMA-WDS.The presence of ternary compounds and the extension of the solid solution and liquid regions were determined to construct the isothermal sections at 1773 and 1873 K of the ternary phase diagram. The data from this work will support further investigations on the feasibility to recover REEs through pyrometallurgical processing.

Novel Approach for the Simultaneous Recovery of Nd from Nd2O3-Containing Slag and the Preparation of High-Purity Si

“…However, the separation of REEs from REE-containing oxide slag remains a major challenge. 25 Silicon (Si) is a strong reductant that can effectively reduce rare earth oxides (REOs) from REO-containing slag to obtain a Si−REE alloy. Si-REE alloys are important deoxidants and alloying agents in many industrial fields because both Si and REEs have a strong affinity for oxygen and can improve the properties of steel and Si-containing alloy materials.…”

“…As REE oxides normally have ultrahigh melting points (e.g., 2573 and 2588 K for Nd 2 O 3 and La 2 O 3 , respectively), slagging agents such as CaO, SiO 2 , Al 2 O 3 , MgO, or CaF 2 are normally used to form low-melting oxide slag to separate REE-containing oxide slag and alloy melt. However, the separation of REEs from REE-containing oxide slag remains a major challenge …”