Mutual Separation Characteristics and Mechanism for Lanthanoid Elements via Gas Phase Complexes with Alkaline Metal and/or Aluminium Chlorides

Abstract

Mutual separations between mixed lanthanoid chlorides, LnCl3 (Ln = Pr and Nd), were performed using a chemical-vapor transporting method via gaseous complexes with a series of alkaline metal chlorides (ACl). The resulting separation factor depended slightly on the alkaline metals, indicating a tendency for the factor to increase with the atomic number; good separation characteristics were observed for gaseous complexes with KCl and RbCl. For complexes in ternary systems, LnCl3–ACl–AlCl3, the codeposition of ACl with LnCl3, which took place in the binary system, LnCl3–ACl, was depressed and LnCl3 was obtained in a form free from the used complex formers.

Comparative study for mutual separation characteristics of binary mixed oxides Y2O3–Ln2O3 (Ln=Dy, Ho and Er) and Ho2O3–Er2O3 using stepwise chlorination–chemical vapor transport reaction mediated by vapor complexes KLnCl4

“…In recent years, a novel promising dry process for the mutual separation of rare earths, which so-called chemical vapor transport reaction (CVT), was studied intensively by Adachi and co-workers [1][2][3][4][5][6][7][8][9][10][11] and Wang and co-workers [12][13][14][15][16][17][18][19][20][21]. They investigated the mutual separation characteristics of rare earth elements from their chloride mixtures, oxide mixtures, concentrates and scraps containing rare earth elements mediated by vapor complexes KLnCl 4 or LnAl n Cl 3n+3 using CVT reaction [1][2][3][4][5][6][7][8][9][10][11][12][13] or stepwise selective chlorination-chemical vapor transport (SC-CVT) reaction [14][15][16][17][18][19][20][21].…”

“…They investigated the mutual separation characteristics of rare earth elements from their chloride mixtures, oxide mixtures, concentrates and scraps containing rare earth elements mediated by vapor complexes KLnCl 4 or LnAl n Cl 3n+3 using CVT reaction [1][2][3][4][5][6][7][8][9][10][11][12][13] or stepwise selective chlorination-chemical vapor transport (SC-CVT) reaction [14][15][16][17][18][19][20][21]. Moreover, the systematic CVT characteristics of pure LnCl 3 (Ln = La-Lu) [4] and SC-CVT characteristics of Ln 2 O 3 (Ln = Sc, Y and La-Lu) [22,23] have been investigated mediated by the vapor complexes KLnCl 4 [22] and LnAl n Cl 3n+3 [4,23].…”

“…doi:10.1016/j.jallcom.2004.06.097 process seems solely depend on the ionic radius of the Ln(III) ion except for Ce [22,23] and Eu [4,23]. That is, the transport efficiency expressed as the total transported amount for LnCl 3 increases with the radius of the Ln(III) ion decreases in the succession from La to Lu, while the main deposition temperature region of LnCl 3 is systematically decreasing in a trend from La to Lu. However, both the total transport efficiency and the main deposition temperature of ScCl 3 and YCl 3 did not agree with their ionic radius values.…”

Mutual separation characteristics for binary mixed oxides Ho2O3–Ln2O3 (Ln = Sc, Y, La, Nd, Sm) using stepwise chlorination-chemical vapor transport reaction mediated by vapor complexes KLnCl4

“…Mutual separation characteristics of rare earth elements by a dry process mediated vapor complexes KLnCl 4 or LnAl n Cl 3n+3 have been investigated intensively from their chloride mixtures, oxide mixtures, concentrates and scraps containing rare earth elements using chemical vapor transport (CVT) reaction or stepwise selective chlorination-chemical vapor transport (SC-CVT) reaction [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. More efficient separation has been observed for oxide mixtures than for chloride mixtures [10,[12][13][14] and using SC-CVT than using CVT reaction [11,15,17,18], and a further improved separation efficiency and total transport yields realized mediated by KCl or KCl-AlCl 3 as complex former instead of only by AlCl 3 as complex former [2,3,10,13,14,20].…”

“…More efficient separation has been observed for oxide mixtures than for chloride mixtures [10,[12][13][14] and using SC-CVT than using CVT reaction [11,15,17,18], and a further improved separation efficiency and total transport yields realized mediated by KCl or KCl-AlCl 3 as complex former instead of only by AlCl 3 as complex former [2,3,10,13,14,20]. Until now, most of the CVT or SC-CVT mutual separation is limited only for the neighboring rare earth elements except the separation for yttrium which possess the special position in rare earth elements from Y 2 O 3 -Nd 2 O 3 [18], Y 2 O 3 -Sm 2 O 3 [18], Y 2 O 3 -Dy 2 O 3 [14], Y 2 O 3 -Ho 2 O 3 [14] and Y 2 O 3 -Er 2 O 3 [14].…”