Separation reagent of platinum group metal, method for separating and recovering platinum group metal, and amide-containing tertiary amine compound

Abstract

The present invention provides a novel separation reagent capable of obtaining a high extraction % of rhodium in a chlorine-based acid solution, which has never existed heretofore, and a method for separating and recovering a platinum group metal using the same. An organic phase composed of an amide-containing tertiary amine separation reagent represented by the structural formula shown below is brought into contact with an acid solution containing a platinum group metal, thereby extracting rhodium, platinum and palladium with the organic phase. Among the metals extracted with the organic phase, rhodium is selectively back-extracted with a highly-concentrated hydrochloric acid solution, while palladium and platinum are back-extracted with a highly-concentrated nitric acid solution: wherein at least one of R 1 , R 2 and R 3 represents an amide group represented by: R 1 to R 3 other than the amide group and R 4 to R 6 represent a group selected from an optionally branched chain hydrocarbon group of 1 to 18 carbon atoms, an alicyclic hydrocarbon group of 1 to 10 carbon atoms, and an aromatic hydrocarbon group of 1 to 14 carbon atoms.

1 . A platinum group metal separation reagent comprising, as an active ingredient, an amide-containing tertiary amine compound represented by the general formula shown below: 
     
       
         
         
             
             
         
       
     
     wherein a least one of R 1 , R 2  and R 3  represents an amide group represented by: 
     
       
         
         
             
             
         
       
     
     and R 1  to R 3  other than the amide group and R 4  to R 6  represent a group selected from an optionally branched chain hydrocarbon group of 1 to 18 carbon atoms, an alicyclic hydrocarbon group of 1 to 10 carbon atoms and an aromatic hydrocarbon group of 1 to 14 carbon atoms. 
   
   
       2 . A method for separating a platinum group metal, which comprises bringing an acidic aqueous phase containing rhodium, platinum and palladium into contact with an organic phase containing the platinum group metal separation reagent according to  claim 1 , thereby extracting rhodium, platinum and palladium into the organic phase. 
   
   
       3 . A method for recovering rhodium, which comprises back-extracting rhodium, platinum and palladium extracted into the organic phase according to  claim 2  with a highly-concentrated hydrochloric acid solution to obtain an aqueous solution containing rhodium. 
   
   
       4 . A method for recovering rhodium, platinum and palladium, which comprises back-extracting rhodium, platinum and palladium extracted into the organic phase according to  claim 2  with a highly-concentrated nitric acid solution to obtain an aqueous solution containing rhodium, platinum and palladium. 
   
   
       5 . A method for separating and recovering rhodium, platinum and palladium wherein a platinum group metal is separated and recovered from a solution to be treated containing at least rhodium, platinum and palladium, the method comprising:
 a first step of bringing an acidic solution to be treated containing at least rhodium, platinum and palladium into contact with an organic phase containing the platinum group metal separation reagent according to  claim 1 , thereby separating rhodium, platinum and palladium from the acidic solution to be treated,   a second step of bringing the resulting organic phase containing rhodium, platinum and palladium into contact with a highly-concentrated hydrochloric acid solution, thereby recovering rhodium,   a third step of bringing a highly-concentrated nitric acid solution into contact with the organic phase after separation of rhodium, thereby recovering platinum and palladium,   a fourth step of bringing an organic phase containing a thiodiglycolamide separation reagent into contact with the resultant aqueous solution containing platinum and palladium, thereby separating palladium and leaving platinum in the aqueous solution, and   a fifth step of bringing a hydrochloric acid solution containing thiourea or an ammonia solution into contact with the resultant organic phase containing palladium, thereby recovering palladium.   
   
   
       6 . An amide-containing tertiary amine compound represented by the general formula shown below: 
     
       
         
         
             
             
         
       
     
     wherein R 1  represents an amide group represented by: 
     
       
         
         
             
             
         
       
     
     R 2  and R 3  represent an optionally branched chain hydrocarbon group of 1 to 11 carbon atoms, R 4  represents an optionally branched chain hydrocarbon group of 1 to 6 carbon atoms, R 5  represents an optionally branched chain hydrocarbon group of 6 to 10 carbon atoms, and R 6  represents an optionally branched chain hydrocarbon group of 1 to 6 carbon atoms. 
   
   
       7 . An amide-containing tertiary amine compound represented by the general formula shown below: 
     
       
         
         
             
             
         
       
     
     wherein R 1  and R 2  represent an amide group represented by: 
     
       
         
         
             
             
         
       
     
     R 3  represents an optionally branched chain hydrocarbon group of 4 to 8 carbon atoms, R 4  represents an optionally branched chain hydrocarbon group of 1 to 6 carbon atoms, R 5  represents an optionally branched chain hydrocarbon group of 6 to 10 carbon atoms, and R 6  represents an optionally branched chain hydrocarbon group of 1 to 6 carbon atoms.