Method and apparatus for recovery of noble metals, including recovery of noble metals from plated and/or filled scrap

Abstract

Systems and methods for the recovery of noble metal from noble-metal-containing material are generally described. Certain embodiments related to systems and methods in which an electric current is transported between an electrode and the noble metal of a noble-metal-containing material to dissolve at least a portion of the noble metal from the noble-metal-containing material. The dissolved noble metal can subsequently be precipitated out of solution and recovered, according to certain embodiments. Noble metals can be recovered from any suitable noble-metal-containing material, including plated and/or filled scrap materials and/or other materials.

What is claimed is: 
     
         1 . A system for recovering noble metals from a noble metal-containing material, comprising:
 an electrode;   a noble-metal containing material; and   an electrolytic solution comprising a sulfonic acid and/or persulfuric acid,   wherein the system is configured such that, when an electric current is transported between the electrode and the noble metal, the noble metal is removed from the noble metal-containing material.   
     
     
         2 . The system of  claim 1 , wherein the electrolytic solution comprises a sulfonic acid. 
     
     
         3 . The system of  claim 1 , wherein the electrolytic solution comprises persulfuric acid. 
     
     
         4 . A system for recovering noble metals from a noble metal-containing material, comprising:
 an electrode;   a noble-metal containing material; and   an electrolytic solution, wherein:   the system is configured such that, when an electric current is transported between the electrode and the noble metal, the noble metal is removed from the noble metal-containing material, and   the bulk of the electrolytic solution is substantially free of a supplemental noble metal oxidant.   
     
     
         5 . The system of any one of  claims 1 - 4 , wherein the electrolytic solution comprises an aqueous solution of a sulfonic acid. 
     
     
         6 . The system of any one of  claims 1 - 5 , wherein the electrolytic solution comprises at least one sulfonic acid represented by:
   RS(═O) 2 —OH,
   
       wherein R is an alkyl group containing 1-12 carbon atoms, an alkenyl group containing 1-12 carbon atoms, a hydroxyalkyl group containing 1-12 carbon atoms, or an aryl group containing 6-12 carbon atoms. 
     
     
         7 . The system of any one of  claims 1 - 6 , wherein the electrolytic solution comprises an aqueous solution of an alkanesulfonic acid, comprising an alkyl group containing 1-5 carbon atoms. 
     
     
         8 . The system of any one of  claims 1 - 7 , wherein the electrolytic solution comprises an aqueous solution of methanesulfonic acid. 
     
     
         9 . The system of any one of  claims 1 - 8 , wherein the electrolytic solution comprises a mixture of acid and water having a water content of less than or equal to about 30 weight percent. 
     
     
         10 . The system of any one of  claims 1 - 9 , wherein the electrolytic solution comprises a peroxymonosulfate ion (SO 5   2− ) and/or a peroxydisulfate ion (S 2 O 8   2− ). 
     
     
         11 . The system of any one of  claims 1 - 10 , wherein the system is configured such that, when an electric current is transported between the electrode and the noble metal, an oxidizing agent is generated at or near the noble-metal-containing material. 
     
     
         12 . The system of  claim 11 , wherein the system is configured such that, when the oxidizing agent is generated in the vicinity of the noble-metal-containing material, the oxidizing agent oxidizes and/or dissolves at least a portion of the noble metal. 
     
     
         13 . The system of any one of  claims 11 - 12 , wherein the oxidizing agent comprises peroxymonosulfuric acid, peroxydisulfuric acid, and/or hydrogen peroxide. 
     
     
         14 . The system of  claim 13 , wherein the peroxymonosulfuric acid and/or the peroxydisulfuric acid is generated by the electrolysis of the electrolytic solution. 
     
     
         15 . The system of any one of  claims 1 - 14 , wherein the system is configured such that, when an electric current is transported between the electrode and the noble metal, at least a portion of the noble metal is chemically reduced to the form a noble-metal-containing product. 
     
     
         16 . The system of  claim 15 , wherein the system is configured such that, when an electric current is transported between the electrode and the noble metal, the noble-metal-containing product, or a precursor thereof, is transported away from the noble-metal-containing material. 
     
     
         17 . The system of any one of  claims 1 - 16 , comprising a separator configured to at least partially separate the elemental noble metal from the electrolytic solution. 
     
     
         18 . The system of any one of  claims 1 - 17 , wherein the system is configured such that, when an electric current is transported between the electrode and the noble metal, a noble-metal-containing product is recovered as a salt of an acid contained in the electrolytic solution. 
     
     
         19 . The system of  claim 18 , wherein the noble-metal-containing product is recovered as a salt of a sulfonic acid. 
     
     
         20 . The system of any one of  claims 1 - 19 , wherein the system is configured such that, when an electric current is transported between the electrode and the noble metal, an elemental noble metal powder is recovered. 
     
     
         21 . The system of any one of  claims 1 - 20 , wherein the system is configured such that, when an electric current is transported between the electrode and the noble metal, at least a portion of the noble metal from the noble-metal-containing material is plated on the electrode. 
     
     
         22 . The system of any one of  claims 1 - 21 , wherein the electrode comprises a metal. 
     
     
         23 . The system of  claim 22 , wherein the metal is chemically inert to the electrolytic solution. 
     
     
         24 . The system of any one of  claims 1 - 23 , wherein the noble-metal-containing material comprises a substrate and a layer comprising a noble metal over the substrate. 
     
     
         25 . The system of  claim 24 , wherein the substrate comprises an electronically conductive material. 
     
     
         26 . The system of  claim 24 , wherein the substrate comprises an electronically non-conductive material and/or a semiconductor material. 
     
     
         27 . The system of  claim 24 , wherein the substrate comprises a metal and/or metal alloy that is less noble than the metal and/or metal alloy contained in the layer. 
     
     
         28 . The system of any one of  claims 1 - 27 , wherein the noble metal comprises gold, silver, platinum, palladium, and/or alloys of these. 
     
     
         29 . The system of any one of  claims 1 - 28 , wherein the system comprises a vessel for containing the electrolytic solution and an agitator that is configured to agitate the electrolytic solution while the electric current is transported between the electrode and the noble metal such that removal of the noble metal is enhanced. 
     
     
         30 . The system of any one of  claims 1 - 29 , wherein the surface of the electrode that is exposed to the electrolytic solution is at least about 50% larger than the surface area of the noble-metal-containing material that is exposed to the electrolytic solution. 
     
     
         31 . A method for recovering a noble metal from a noble-metal-containing material, comprising transporting an electric current between an electrode and a noble metal of the noble-metal-containing material positioned within an electrolytic solution comprising a sulfonic acid and/or persulfuric acid such that at least a portion of the noble metal is removed from the noble-metal-containing material. 
     
     
         32 . The method of  claim 31 , wherein the electrolytic solution comprises a sulfonic acid. 
     
     
         33 . The system of  claim 31 , wherein the electrolytic solution comprises persulfuric acid. 
     
     
         34 . A method for recovering a noble metal from a noble-metal-containing material, comprising transporting an electric current between an electrode and a noble metal of the noble-metal-containing material positioned within an electrolytic solution that is substantially free of a supplemental noble metal oxidant such that at least a portion of the noble metal is removed from the noble-metal-containing material. 
     
     
         35 . The method of any one of  claims 31 - 34 , wherein the electrolytic solution comprises an aqueous solution of a sulfonic acid. 
     
     
         36 . The method of any one of  claims 31 - 35 , wherein the electrolytic solution comprises at least one sulfonic acid represented by:
   RS(═O) 2 —OH,
   
       where R symbolizes an alkyl group containing 1-12 carbon atoms, an alkenyl group containing 1-12 carbon atoms, a hydroxyalkyl group containing 1-12 carbon atoms, or an aryl group containing 6-12 carbon atoms. 
     
     
         37 . The method of any one of  claims 31 - 36 , wherein the electrolytic solution comprises an aqueous solution of an alkanesulfonic acid, comprising an alkyl group containing 1-5 carbon atoms. 
     
     
         38 . The method of any one of  claims 31 - 37 , wherein the electrolytic solution comprises an aqueous solution of methanesulfonic acid. 
     
     
         39 . The method of any one of  claims 31 - 38 , wherein the electrolytic solution comprises a mixture of acid and water having a water content of less or equal to 30 weight percent. 
     
     
         40 . The method of any one of  claims 31 - 39 , wherein the electrolytic solution comprises a peroxymonosulfate ion (SO 5   2− ) and/or a peroxydisulfate ion (S 2 O 8   2− ). 
     
     
         41 . The method of any one of  claims 31 - 40 , wherein transporting the electric current between the electrode and the noble metal generates an oxidizing agent at or near the noble-metal-containing material. 
     
     
         42 . The method of  claim 41 , wherein the oxidizing agent oxidizes and/or dissolves at least a portion of the noble metal. 
     
     
         43 . The method of any one of  claims 41 - 42 , wherein the oxidizing agent is peroxymonosulfuric acid, peroxydisulfuric acid, and/or hydrogen peroxide. 
     
     
         44 . The method of  claim 43 , wherein the peroxymonosulfuric acid and/or the peroxydisulfuric acid is generated by the electrolysis of the electrolytic solution. 
     
     
         45 . The method of any one of  claims 31 - 44 , wherein at least a portion of the noble metal is chemically reduced to the form a noble-metal-containing product. 
     
     
         46 . The method of  claim 45 , wherein the noble-metal-containing product, or a precursor thereof, is transported away from the noble-metal-containing material. 
     
     
         47 . The method of any one of  claims 31 - 46 , wherein noble metal is at least partially separated from the electrolytic solution using a solid-liquid separation technique. 
     
     
         48 . The method of any one of  claims 31 - 47 , wherein a noble-metal-containing product is recovered as a salt of an acid within the electrolytic solution. 
     
     
         49 . The method of  claim 48 , wherein the noble-metal-containing product is recovered as a salt of a sulfonic acid. 
     
     
         50 . The method of any one of  claims 31 - 49 , wherein at least a portion of the noble metal is plated on the electrode. 
     
     
         51 . The method of any one of  claims 31 - 50 , wherein the electrode comprises a metal. 
     
     
         52 . The method of  claim 51 , wherein the metal is chemically inert to the electrolytic solution. 
     
     
         53 . The method of any one of  claims 31 - 52 , wherein the noble-metal-containing material comprises a substrate and a layer comprising a noble metal over the substrate. 
     
     
         54 . The method of  claim 53 , wherein the substrate comprises an electronically conductive material. 
     
     
         55 . The method of  claim 53 , wherein the substrate comprises an electronically non-conductive material and/or a semiconductor material. 
     
     
         56 . The method of  claim 53 , wherein the substrate comprises a metal and/or metal alloy that is less noble than the metal and/or metals alloy contained in the layer. 
     
     
         57 . The method of any one of  claim 31 - 56 , wherein the noble metal comprises gold, silver, platinum, palladium, and/or alloys of these. 
     
     
         58 . The method of any one of  claim 31 - 57 , comprising agitating the electrolytic solution while the electric current is transported between the electrode and the noble metal thereby enhancing the removal of the noble metals. 
     
     
         59 . The method of any one of  claims 31 - 58 , comprising maintaining the current density at the noble-metal-containing material at 0.01 A/cm 2  or more. 
     
     
         60 . The method of any one of  claims 31 - 59 , comprising recovering a noble metal at a concentration higher than its concentration in the noble-metal-containing material. 
     
     
         61 . The method of any one of  claims 31 - 60 , comprising recovering the noble metal at a concentration higher than or equal to the concentration of the noble metal in a coating and/or plating in the original noble-metal containing material. 
     
     
         62 . The method of any one of  claims 31 - 61 , comprising recovering the balance of the noble-metal containing material in a substantially undamaged form. 
     
     
         63 . The method of any one of  claims 31 - 62 , wherein non-noble metals which dissolve in the electrolytic solution during the transporting of the electric current between the electrode and the noble metal simultaneously deposit on the cathode. 
     
     
         64 . The method of  claim 63 , comprising continuously reusing the electrolytic solution. 
     
     
         65 . The method of any one of  claims 31 - 64 , comprising containing the electrolytic solution in a vessel and keeping a volume of the electrolytic solution substantially constant during the transporting of the electric current between the electrode and the noble metal. 
     
     
         66 . The method of  claim 65 , wherein keeping the volume of the electrolytic solution constant comprises discharging a portion of the electrolytic solution from the vessel and providing a makeup stream of electrolytic solution to the vessel. 
     
     
         67 . The method of any one of  claims 31 - 66 , wherein the surface of the electrode that is exposed to the electrolytic solution is at least about 50% greater than the surface of the noble-metal-containing material that is exposed to the electrolytic solution. 
     
     
         68 . The method of any one of  claims 31 - 67 , comprising maintaining the temperature of the electrolytic solution between about 10° C. and about 100° C. 
     
     
         69 . A system for the recovery of noble metal from noble metal containing material, comprising:
 a rotatable container positioned within a vessel configured to contain an electrolytic liquid; and   an electrically conductive pathway configured such that, when the noble metal containing material is contained within the rotatable container, the electrically conductive pathway remains in electrical communication with the noble metal containing material when the container is rotated.