Purified nickel solutions using successive solvent extractions

Abstract

Methods of recovering a nickel salt are disclosed. The method includes removing one or more impurities from an aqueous leach solution including cobalt, manganese, and nickel salts to produce a first purified aqueous solution including the cobalt, manganese, and nickel salts. The method includes extracting the cobalt and manganese salts from the first purified aqueous solution in a first liquid-liquid extraction step using a first organic extractant to produce an aqueous raffinate solution including the nickel salt and a first loaded organic solution including the cobalt and manganese salts. The method further includes extracting the nickel salt from the aqueous raffinate solution in a second liquid-liquid extraction step using a second organic extractant to produce a second loaded organic solution including the nickel salt. Systems for recovering a nickel salt are also disclosed.

1 . A method of recovering a nickel salt, comprising:
 removing one or more impurities from an aqueous leach solution comprising cobalt, manganese, and nickel salts to produce a first purified aqueous solution comprising the cobalt, manganese, and nickel salts;   extracting the cobalt and manganese salts from the first purified aqueous solution in a first liquid-liquid extraction step using a first organic extractant to produce an aqueous raffinate solution comprising the nickel salt and a first loaded organic solution comprising the cobalt and manganese salts; and   extracting the nickel salt from the aqueous raffinate solution in a second liquid-liquid extraction step using a second organic extractant to produce a second loaded organic solution comprising the nickel salt.   
     
     
         2 . The method of  claim 1 , wherein the aqueous leach solution is prepared by leaching metal salts from a granular mass of crushed battery materials including cathode materials and anode materials. 
     
     
         3 . The method of  claim 1 , wherein removing the one or more impurities from the leach solution comprises precipitation by pH adjustment. 
     
     
         4 . The method of  claim 1 , wherein the first organic extractant comprises a dialkylphosphinic acid. 
     
     
         5 . The method of  claim 4 , wherein the dialkylphosphinic acid is dissolved in an organic diluent to a concentration of about 10% to about 20%. 
     
     
         6 . The method of  claim 1 , wherein, during the first liquid-liquid extraction step, the first purified aqueous solution has an equilibrium pH of less than  7 . 
     
     
         7 . The method of  claim 6 , wherein the equilibrium pH is from about 4 and about 6. 
     
     
         8 . The method of  claim 6 , wherein the equilibrium pH is achieved by increasing the pH of the first purified aqueous solution using a water-soluble base. 
     
     
         9 . The method of  claim 6 , wherein the first organic extractant comprises a dialkylphosphinic acid and wherein the equilibrium pH is achieved by saponification of the dialkylphosphinic acid. 
     
     
         10 . The method of  claim 9 , wherein a water-soluble base achieves a degree of saponification of the dialkylphosphinic acid of 30-35%. 
     
     
         11 . The method of  claim 1 , wherein the first liquid-liquid extraction step occurs at a temperature of from about 40° C. to about 60° C. 
     
     
         12 . The method of  claim 1 , wherein the second organic extractant comprises an alkylcarboxylic acid. 
     
     
         13 . The method of  claim 12 , wherein the alkylcarboxylic acid is dissolved in an organic diluent to a concentration of about 30% to about 50%. 
     
     
         14 . The method of  claim 1 , wherein, during the second liquid-liquid extraction step, the aqueous raffinate solution has an equilibrium pH of less than 7. 
     
     
         15 . The method of  claim 14 , wherein the equilibrium pH is from about 5 to about 6. 
     
     
         16 . The method of  claim 15 , wherein the equilibrium pH is achieved by increasing the pH of the aqueous raffinate solution using a water-soluble base. 
     
     
         17 . The method of  claim 15 , wherein the second organic extractant comprises an alkylcarboxylic acid and wherein the equilibrium pH is achieved by saponification of the alkylcarboxylic acid. 
     
     
         18 . The method of  claim 17 , wherein a water-soluble base achieves a degree of saponification of the alkylcarboxylic acid of 25-35%. 
     
     
         19 . The method of  claim 1 , further comprising performing a third extraction step on the first loaded organic solution to produce an enriched cobalt and manganese salt solution and a first waste solution comprising spent first organic extractant. 
     
     
         20 . The method of  claim 19 , further comprising regenerating the spent first organic extractant with a first acidic regenerant. 
     
     
         21 . The method of  claim 1 , further comprising a fourth extraction step on the second loaded organic solution to produce a second purified aqueous solution comprising the nickel salt and a second waste solution comprising spent second organic extractant. 
     
     
         22 . The method of  claim 21 , further comprising regenerating the second spent organic extractant with a second acidic regenerant. 
     
     
         23 . The method of  claim 21 , further comprising recovering the nickel salt from the second purified aqueous solution. 
     
     
         24 . The method of  claim 21 , wherein the nickel salt is recovered from the second purified aqueous solution by crystallization. 
     
     
         25 . A system for recovering a nickel salt, comprising:
 an impurity removal stage constructed and arranged to remove one or more impurities from an aqueous leach solution comprising cobalt, manganese, and nickel salts to produce a first purified aqueous solution comprising the cobalt, manganese, and nickel salts;   a first extraction stage constructed and arranged to remove the cobalt and manganese salts from the first purified aqueous solution to produce an aqueous raffinate solution comprising the nickel salt and a first loaded organic solution comprising the cobalt and manganese salts; and   a second extraction stage constructed and arranged to remove the nickel salt from the aqueous raffinate solution to produce a second loaded organic solution comprising the nickel salt.