Solubilization of scandium from fluoride bearing materials

Abstract

A method of selectively removing scandium from a scandium and fluoride-containing feed material includes providing the scandium-containing feed material, acid leaching the scandium-containing feed material with at least one acid in a presence of at least one of an aluminum or iron containing salt to form a scandium containing stream, and purifying the scandium containing stream to form a scandium compound end product.

1 . A method of selectively removing scandium from a scandium-containing feed material, comprising:
 providing the scandium-containing feed material;   acid leaching the scandium-containing feed material with at least one acid in a presence of at least one of an aluminum or iron containing salt to form a scandium containing stream; and   purifying the scandium containing stream to form a scandium compound end product.   
     
     
         2 . The method of  claim 1 , wherein the at least one of the aluminum containing salt or the iron containing salt is added to the scandium-containing feed material prior to the step of acid leaching. 
     
     
         3 . The method of  claim 1 , wherein the at least one of the aluminum containing salt or the iron containing salt is dissolved in a solution comprising the least one acid. 
     
     
         4 . The method of  claim 1 , wherein the at least one of the aluminum containing salt or the iron containing salt is separately added to a reactor vessel in which the acid leaching takes place. 
     
     
         5 . The method of  claim 1 , wherein the at least one acid is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid. 
     
     
         6 . The method of  claim 1 , wherein the scandium compound end product comprises scandium hydroxide, scandium oxide, scandium chloride, scandium oxalate or scandium carbonate. 
     
     
         7 . The method of  claim 1 , wherein the step of purifying comprises at least one of solvent extraction, ion exchange and stripping. 
     
     
         8 . The method of  claim 1 , wherein the scandium-containing feed material comprises a solid material containing fluorine which forms a complex with aluminum ions or iron ions during the acid leaching. 
     
     
         9 . The method of  claim 8 , wherein an amount of aluminum or iron in a reactor vessel in which the acid leaching takes place is sufficient to prevent scandium precipitation. 
     
     
         10 . The method of  claim 1 , wherein the step of acid leaching the scandium-containing feed material with at least one acid takes place in the presence of the aluminum containing salt. 
     
     
         11 . The method of  claim 10 , wherein the aluminum containing salt is AlCl 3  with or without waters of hydration. 
     
     
         12 . The method of  claim 10 , wherein the aluminum containing salt comprises Al 2 (SO 4 ) with or without waters of hydration, or aluminum hydroxide with or without waters of hydration. 
     
     
         13 . The method of  claim 10 , wherein an atomic ratio of aluminum to fluorine is greater than or equal to 3 in a reactor vessel in which the acid leaching takes place. 
     
     
         14 . The method of  claim 13 , wherein the atomic ratio of aluminum to scandium in the reactor vessel in which the acid leaching takes place is greater than or equal to 2. 
     
     
         15 . The method of  claim 10 , wherein the at least one acid has a pH of 2 or less during the step of acid leaching. 
     
     
         16 . The method of  claim 10 , wherein the step of acid leaching comprises:
 a first acid leaching substep using an acid having a pH between 3 and 5 to form and remove an aluminum fluoride complex; and   a subsequent second acid leaching substep using the at least one acid having a pH of 2 or less to form the scandium containing stream.   
     
     
         17 . A method of selectively removing scandium from a scandium fluoride containing slurry, comprising:
 adding an aluminum containing salt to the scandium fluoride containing slurry to form at least one aluminum fluoride complex and causing the scandium fluoride to dissolve;   removing the at least one aluminum fluoride complex from the slurry to provide a scandium containing stream; and   purifying the scandium containing stream to form a scandium compound end product.   
     
     
         18 . The method of  claim 17 , wherein the aluminum containing salt is AlCl 3  with or without waters of hydration. 
     
     
         19 . The method of  claim 17 , wherein the aluminum containing salt is Al 2 (SO 4 ) with or without waters of hydration. 
     
     
         20 . The method of  claim 17 , wherein:
 the scandium compound end product comprises scandium hydroxide, scandium oxide, scandium chloride, scandium oxalate or scandium carbonate; and   the step of purifying comprises at least one solvent extraction, ion exchange and stripping.