Recovery of rare earth metals from ferromagnetic alloys
Methods for recovery of at least one rare earth metal from ferromagnetic alloy are described, and further methods of atomic hydrogen decrepitation of a ferromagnetic alloy.
1 . A method of atomic hydrogen decrepitation of a ferromagnetic alloy, wherein the method comprises;
electrolyzing an aqueous solution, thereby releasing an atomic hydrogen from a cathode within an electrochemical cell; and
reacting the ferromagnetic alloy with the released atomic hydrogen, wherein the ferromagnetic alloy is attached to the cathode;
to obtain a ferromagnetic alloy powder having grain size ≤50 μm.
2 . The method of claim 1 , wherein the aqueous solution comprises a KOH or NaOH aqueous solution.
3 . The method of claim 1 , wherein the atomic hydrogen is released from the cathode by a reduction reaction of 2H + ( )+2e − →2H( ).
4 . The method of claim 3 , wherein the H+ is a result of electrolysis of the water (H2O) within the aqueous solution electrolysis step.
5 . The method of claim 1 , wherein the cathode is copper, nickel, steel, titanium or any combination thereof.
6 . The method of claim 1 , wherein, an anode within the electrochemical cell is a lead, nickel, steel or combination thereof.
7 . The method of claim 1 , wherein the aqueous solution electrolysis is conducted at room temperature.
8 . The method of claim 1 , wherein the aqueous solution electrolysis is conducted at a potential is between 4-10 V.
9 . A method for recovery of at least one rare earth metal from ferromagnetic alloy, the method comprises:
(a) Pre-treating a ferromagnetic alloy by atomic hydrogen decrepitation according to claim 1 to form a powder ferromagnetic alloy;
(b) reacting the ferromagnetic powder alloy with at least one chlorine-containing gas to obtain a volatile iron-containing chloride product and non-volatile at least one rare earth metal chloride;
(c) providing air flow to said volatile iron-containing chloride product, thereby oxidizing the iron-containing chloride product to iron oxide;
(d) separating said iron oxide product and non-volatile at least one rare earth metal chloride;
(e) cooling said separated non-volatile at least one rare earth metal chloride;
(f) electrolyzing said cooled non-volatile at least one rare earth metal chloride;
thereby recovering said at least one rare earth metal.
10 . The method of claim 1 , wherein said electrolyzing is performed using the cathode of copper, nickel, steel, titanium or combination thereof, and an anode of lead, nickel, steel or combination thereof.
11 . At least one rare earth metal composition prepared by the method of claim 9 .
12 . A method for recovery of at least one rare earth metal from a ferromagnetic alloy, the method comprises:
(a) reacting the ferromagnetic alloy with at least one chlorine-containing gas to obtain a volatile iron-containing chloride product and non-volatile at least one rare earth metal chloride;
(b) providing air flow to said volatile iron-containing chloride product, thereby oxidizing the iron-containing chloride product to iron oxide;
(c) separating said iron oxide product and non-volatile at least one rare earth metal chloride;
(d) cooling said separated non-volatile at least one rare earth metal chloride;
(e) electrolyzing said cooled non-volatile at least one rare earth metal chloride;
thereby recovering said at least one rare earth metal.
13 . The method of claim 12 , wherein prior to reacting the ferromagnetic alloy with at least one chlorine-containing gas of step (a), an optional step is performed:
pre-treating a ferromagnetic alloy by atomic hydrogen decrepitation method, comprising electrolyzing an aqueous solution, thereby releasing an atomic hydrogen from a cathode within an electrochemical cell; and reacting the ferromagnetic alloy with the released atomic hydrogen, wherein the ferromagnetic alloy is attached to the cathode; to obtain a ferromagnetic alloy powder having grain size ≤50 μm.
14 . The method of claim 13 , wherein the decrepitation is performed at room temperature.
15 . The method of claim 12 , wherein the at least one rare earth metal is selected from cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb), and yttrium (Y).
16 . The method of claim 12 , wherein the reaction of step (b) is performed at a temperature of between 400° C. and 450° C.
17 . The method of claim 12 , wherein the at least one chlorine-containing gas in reaction of step (a) is present in an amount of 0.5-2.0 kg of the chlorine per 1 kg of the ferromagnetic alloy.
18 . The method of claim 12 , wherein the air flow to the volatile iron-containing chloride product of step (b) is present in an amount of 0.5-2.0 kg of the air per 1 kg of the volatile iron-containing chloride product.
19 . At least one rare earth metal composition prepared by the method of claim 12 .