High Gradient Magnetic Separation of Pure Gd2O3 Particles from Pure La2O3 Particles

Abstract

Rare earth oxides such as La2O3 and Gd2O3 are abundant in waste optical glass. The separation of rare earth oxides is beneficial to the recycling of rare earth resources. In this study, the rare earth oxide Gd2O3 particles were separated from La2O3 particles using high gradient magnetic separation, and the influence of different fluid media (i.e., water, anhydrous ethanol, and their mixture) on the separation results was investigated. By using the measured zeta potential of oxide particles in water/ethanol of different pH and water with different dispersants (Na2SiO3 9H2O, citric acid, Na2CO3, and sodium hexametaphosphate), the DLVO (Derjaguin–Landau–Verwey–Overbeek) potential calculations and their analysis applied to high gradient magnetic separation results were also performed. The results showed that using anhydrous ethanol or adding a dispersant in water as a fluid medium can promote the separation of magnetic Gd2O3 particles under a high-gradient magnetic field. Among the different conditions, anhydrous ethanol can improve the grade of Gd2O3 to 95% from 70% with water. Furthermore, ethanol can be reused after filtration, making it an environmentally friendly fluid medium. Among the four dispersants, sodium hexametaphosphate, Na2SiO3, and Na2CO3 can also increase the separation rate of La2O3 and Gd2O3 to about 95%. The effect of citric acid on the separation performance is slightly worse, and the recovery rate of Gd2O3 is 80%. This study provides a new reference for selecting a fluid medium for magnetic separation.

Rigidity‐Tunable Materials for Soft Engineering Systems

“…Ga, with a melting point of 29.8 °C, exhibits a stiffness of 9.8 GPa when solidified at lower temperatures. [ 51,52 ] Conversely, Bi has a melting point of 270°C and exhibits a stiffness of 32 GPa at room temperature, whereas In boasts a melting point of 156.6 °C and a stiffness of 11 GPa. [ 53,54 ] Additionally, combining different LMPAs can modify their mechanical properties and melting points to meet specific design requirements.…”

Current Status and Outlook of Low‐Melting‐Point Metals in Biomedical Applications

“…To understand the efficacy of low‐melting‐point Galinstan in thermal energy storage applications, microchannels, soft robotics, and magnetorheological devices, there have been many recent studies on its wetting properties. [ 54 ] Because Galinstan is easily oxidized in air, related studies must be conducted in an inert nitrogen atmosphere (<0.5 ppm oxygen) to maintain its fluid‐like properties. Although the contact angle varies with substrate and surface structure, the temperature has little effect.…”

“…First, pure gallium, as mentioned earlier, has a low melting point, and when gallium is mixed with other metal elements at the atomic level, the larger distance between atoms results in significant structural anisotropy, weakening the bonding and causing the crystal structure to break at low temperatures, leading to a lower melting point. [ 52 ] Additionally, alloys such as GaZn, GaSnBi, GaSn, [ 53 ] AlGaSn, AlGaIn, AlGaInSn [ 54 ] are also known to exist as liquids at room temperature, indicating that they have low melting points.…”

Ga‐Based Liquid Metals: Versatile and Biocompatible Solutions for Next‐Generation Bioelectronics

“…The phase diagram of Ga, as depicted in Figure 2b, reveals the presence of various stable and sub‐stable phases including α‐Ga, β‐Ga, γ‐Ga, δ‐Ga, and Ga‐II phases, showing the complex and diverse atomic configurations Ga exhibits across different temperature ranges. [ 49,50 ] In ambient conditions, Ga exists in a stable phase as α‐Ga and adopts a unique orthorhombic system with both covalent and metallic bonding. [ 51 ] In other phases of Ga, for example, the structure of β‐Ga is monoclinic, dominated by metallic bonds without covalent bonds as shown in Figure 2c.…”