Methods and apparatus for production of rare earth elements from coal and clay ores

Abstract

A method of extracting a rare earth element from a coal deposit utilizing a ligand to capture the rare earth element includes crushing the coal deposit to form a coal particulate and forming a first pregnant leachate including the coal particulate and a ligand. The method further includes extracting the metal impurities via an ion exchange or floatation to form a reduced leachate and forming a second pregnant leachate comprising the reduced leachate and the ligand. The method also includes extracting the rare earth element from the reduced leachate via an ion exchange or floatation, capturing the rare earth element in the binding site of the ligand, and desorbing the rare earth element from the ligand.

1 . A method of separating a rare earth element from a feedstock of coal and clay ores, comprising:
 acid leaching the feedstock at a pH less than about 5;   capturing the rare earth element with a ligand; and   releasing the rare earth element from the ligand.   
     
     
         2 . The method of  claim 1 , wherein the rare earth element comprises at least one of gallium, germanium, cerium, lanthanum, neodymium, praseodymium, scandium, yttrium, dysprosium, terbium, samarium, ytterbium, europium, promethium, gadolinium, holmium, lutetium, thulium, or erbium. 
     
     
         3 . The method of  claim 1 , wherein the ligand comprises a binding protein. 
     
     
         4 . The method of  claim 1 , wherein the ligand comprises a Lanmodulin. 
     
     
         5 . The method of  claim 1 , wherein the ligand comprises at least 6 binding sites. 
     
     
         6 . The method of  claim 1 , further comprising sorting the rare earth element as either a heavy rare earth element, a middle rare earth element, or a light rare earth element. 
     
     
         7 . The method of  claim 1 , further comprising beneficiating the feedstock prior to acid leaching. 
     
     
         8 . The method of  claim 7 , wherein beneficiating the feedstock comprises heating the feedstock to a first temperature for a first duration; and
 heating the feedstock to a second, higher temperature for a second duration.   
     
     
         9 . The method of  claim 1 , wherein the method extracts at least about 80% of the rare earth element from the feedstock. 
     
     
         10 . A method of extracting a rare earth element from a coal deposit utilizing a ligand to capture the rare earth element, comprising:
 crushing the coal deposit to form a coal particulate, wherein the coal deposit comprises a rare earth element and metal impurities;   forming a first pregnant leachate including the coal particulate and a ligand;   extracting the metal impurities via an ion exchange or floatation to form a reduced leachate;   forming a second pregnant leachate comprising the reduced leachate and the ligand;   extracting the rare earth element from the reduced leachate via acid leaching;   capturing the rare earth element in the binding site of the ligand; and   desorbing the rare earth element from the ligand.   
     
     
         11 . The method of  claim 10 , wherein the ligand comprises at least one of a glycolipid ligand, a rhamnolipid ligand or a xylulose. 
     
     
         12 . The method of  claim 10 , wherein the metal impurities include at least one of iron or aluminum. 
     
     
         13 . The method of  claim 10 , wherein the coal particulate comprises a diameter less than about 5 mm. 
     
     
         14 . The method of  claim 10 , further comprising separating and recycling the ligand after extracting the metal impurities and after desorbing the rare earth element from the ligand. 
     
     
         15 . The method of  claim 10 , wherein desorbing the rare earth element from the ligand comprises controlling the pH to release the rare earth element based on an atomic number of the rare earth element. 
     
     
         16 . A system to extract a rare earth element from a coal deposit, comprising:
 a molecular exclusion system comprising:
 a separation column configured to separate a first solution, the first solution comprising an acid solution including a ligand and coal particulate having rare earth elements and metal impurities therein, the coal particulate derived from the coal deposit, the separation column configured to capture the metal impurities and output a reduced solution; and 
 a second solution configured to separate the reduced solution and capture at least one rare earth element from the reduced solution; 
 a third solution configured to release the captured at least one rare earth element; 
   wherein each of the first solution and the second solution comprises a binding ligand expressed on a column configured to capture the rare earth element.   
     
     
         17 . The system of  claim 16 , wherein the ligand comprises a rare earth element binding protein. 
     
     
         18 . The system of  claim 16 , wherein the first solution and the second solution operate in a cyclical fashion to recycle the ligand. 
     
     
         19 . The system of  claim 16 , wherein the ligand is functionalized to capture a predefined category of rare earth element. 
     
     
         20 . The system of  claim 16 , wherein the acid solution comprises a pH less than about 5.