Methods of recovering rare earth elements

A method of recovering one or more rare earth elements from a rare earth containing material, wherein said method comprises the steps of:

• providing the rare earth containing material having aluminum and at least one rare earth element therein, wherein the weight percentage of the aluminum, as its oxide equivalent, is defined as AO% and the weight percentage of the at least one rare earth element, as its oxide equivalent, is defined as RO%;
• and
• reacting the rare earth containing material with a solution to extract a relatively large proportion of at least a portion of the at least one rare earth element from the rare earth containing material, while extracting only a relatively moderate proportion of the aluminum, such that the resulting weight percentage of the at least one rare earth element, as its oxide equivalent, remaining in the rare earth containing material, defined as RF%, and the resulting weight percentage of aluminum, as its oxide equivalent, remaining in the rare earth containing material, defined as AF%, satisfy the following relationships:
• RF% is less than or equal to approximately 0.4 RO%;
• and
• AF% is greater than or equal to approximately 0.5 AO%.

A method of recovering one or more rare earth elements from a rare earth containing material, wherein said method comprises the steps of:

• providing the rare earth containing material, of a weight WRE, having aluminum and at least one rare earth element therein, wherein the weight percentage of the aluminum, represented as its weight percent oxide equivalent Al2O3, is defined as AO% and the weight percentage of the at least one rare earth element, represented as its weight percent oxide equivalent, is defined as RO%;
• and
• reacting the rare earth containing material with a solution, of a volume VS, to extract a majority of the at least one rare earth element from the rare earth containing material, while extracting no more than half of the aluminum, such that the resulting weight percentage of the at least one rare earth element, as its oxide equivalent, remaining in the rare earth containing material, defined as Rf%, and the resulting weight percentage of aluminum, as its oxide equivalent, remaining in the rare earth containing material, defined as Af%, satisfy the following relationships:
• x
• =
• R
• o
• A
• o
• ×
• A
• f
• -
• A
• o
• R
• f
• -
• R
• o
• where x is less than or equal to about 0.8;
• and
• y=WRE (in grams)/VS (in milliliters),
• where y is greater than or equal to about 0.025.