Selective separation and crystal characterization of RE‐phases from RE‐bearing slag systems: Calcium cerite and cefluosil

Abstract

The industrial RE-bearing (rare-earth-bearing) slag has a considerable concentration of rare-earth elements (REEs), so the recovery of REEs resources from these systems has attracted widespread attention. However, the basic data of RE phases is seriously lacked and divergent, which greatly limits the efficient utilization. In this study, in situ separation of RE phases from RE-bearing slag systems was conducted via super gravity, and the high-purity crystals of calcium cerite (CaO: 13.53 wt.%, SiO 2 : 26.02 wt.%, Ce 2 O 3 : 65.45 wt.%) and cefluosil (CaO: 14.67 wt.%, SiO 2 : 22.14 wt.%, CaF 2 : 2.64 wt.%, Ce 2 O 3 : 67.23 wt.%) were selectively separated from the CaO-SiO 2 -Ce 2 O 3 and CaO-SiO 2 -CaF 2 -Ce 2 O 3 systems with the high REEs recovery percentages of 96.10% and 98.23%, respectively. Based on the characterization of high-purity calcium cerite and cefluosil crystals, the chemical formula, crystal structure, and Rietveld refinement were characterized, and the data has been assigned the deposition numbers of 2130965 and 2142394 in CCDC database. This study supplements the lack of basic data of RE crystals and provides theoretical reference and guidance for the utilization of RE-bearing slag systems.

Crystallization behavior and crystal characterization of V-spinel in vanadium slag via in situ separation: displacement mechanism of V and Ti

“…Therefore, the gravity coefficient of the super-gravity field can be expressed as an equation related to the rotation speed of the centrifuge under the condition of neglecting Earth's gravity, which is eqn (1). 20,21 where G is the gravity coefficient, g is the normal-gravitational acceleration ( g = 9.80 m s −2 ), ω is the angular velocity (rad s −1 ), N is the rotating speed (rpm), and R is the distance from the centrifugal axis to the sample center ( R = 0.25 m).…”

“…Therefore, the gravity coefficient of the super- CrystEngComm Paper gravity field can be expressed as an equation related to the rotation speed of the centrifuge under the condition of neglecting Earth's gravity, which is eqn (1). 20,21…”

“…In order to disclose the crystal structure and elemental substitution of V-spinel in vanadium slag, in situ separation of V-spinel formed in molten vanadium slag was carried out via super-gravity based on its significant enhancement on mass transfer and interphase separation. 17–22…”

“…In order to disclose the crystal structure and elemental substitution of V-spinel in vanadium slag, in situ separation of V-spinel formed in molten vanadium slag was carried out via super-gravity based on its significant enhancement on mass transfer and interphase separation. [17][18][19][20][21][22] In this study, the crystallization behavior of V-spinel was studied, and in situ separation of high-purity V-spinel crystals from molten vanadium slag was conducted via super-gravity. Moreover, the crystal structures of various high-purity V-spinels were characterized, and the displacement mechanism of V and Ti in V-spinel was verified.…”

Effect of TiO₂ Addition and Cooling Rate on Crystallization Behavior of Separated Slag Containing Low-grade RE

“…The possible phase was further detected as britholite which evolved from Ca 5 (PO 4 ) 3 F in the CaO-SiO 2 -CaF 2 -P 2 O 5 -Ce 2 O 3 system by Lan et al 17) . The phase equilibrium relations of related slag system in specific temperature were studied by Lan and Qiu respectively 18,19) . However, the available thermodynamics and kinetics data of britholite is still limited [20][21][22] .…”