Wet based formulations for the selective removal of noble metals

Abstract

Compositions and processes for leaching noble metals from materials comprising said noble metals. Advantageously, the halide-based composition is environmentally friendly and effectively removes noble metals at room temperature without the need for high pressures and electrodes.

1 . A leaching composition comprising, at least one oxidizing agent, at least one halide, at least one acid, and at least one solvent. 
     
     
         2 . The leaching composition of  claim 1 , wherein the composition includes a pH of less than about 2. 
     
     
         3 . The leaching composition of  claim 1 , wherein the at least one oxidizing agent comprises at least one species selected from the group consisting of ozone, nitric acid (HNO 3 ), bubbled air, cyclohexylaminosulfonic acid, hydrogen peroxide (H 2 O 2 ), oxone, ammonium peroxomonosulfate, ammonium chlorite (NH 4 ClO 2 ), ammonium chlorate (NH 4 ClO 3 ), ammonium iodate (NH 4 IO 3 ), ammonium perborate (NH 4 BO 3 ), ammonium perchlorate (NH 4 ClO 4 ), ammonium periodate (NH 4 IO 3 ), ammonium persulfate ((NH 4 ) 2 S 2 O 8 ), ammonium hypochlorite (NH 4 ClO), sodium persulfate (Na 2 S 2 O 8 ), sodium hypochlorite (NaClO)), potassium polyatomic salts (e.g., potassium iodate (KIO 3 ), potassium permanganate (KMnO 4 ), potassium persulfate, potassium persulfate (K 2 S 2 O 8 ), potassium hypochlorite (KClO), tetramethylammonium chlorite ((N(CH 3 ) 4 )ClO 2 ), tetramethylammonium chlorate ((N(CH 3 ) 4 )ClO 3 ), tetramethylammonium iodate ((N(CH 3 ) 4 )IO 3 ), tetramethylammonium perborate ((N(CH 3 ) 4 )BO 3 ), tetramethylammonium perchlorate ((N(CH 3 ) 4 )ClO 4 ), tetramethylammonium periodate ((N(CH 3 ) 4 )IO 4 ), tetramethylammonium persulfate ((N(CH 3 ) 4 )S 2 O 8 ), tetrabutylammonium peroxomonosulfate, peroxomonosulfuric acid, urea hydrogen peroxide ((CO(NH 2 ) 2 )H 2 O 2 ), peracetic acid (CH 3 (CO)OOH), sodium nitrate, potassium nitrate, ammonium nitrate, and combinations thereof. 
     
     
         4 . The leaching composition of  claim 1 , wherein the at least one oxidizing agent comprises a nitrate salt selected from the group consisting of nitric acid, sodium nitrate, potassium nitrate, ammonium nitrate, tetraalkylammonium nitrate, and combinations thereof, preferably nitric acid. 
     
     
         5 . The leaching composition of  claim 1 , wherein the at least one halide comprises an alkaline chloride. 
     
     
         6 . The leaching composition of  claim 1 , wherein the at least one halide comprises a chloride species selected from the group consisting of hydrochloric acid, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, magnesium chloride, calcium chloride, strontium chloride, ammonium chloride, quaternary ammonium chloride salts, and combinations thereof, with the proviso that the chloride species cannot include copper chloride, chlorine gas, or a second, different halide in the compound, preferably sodium chloride. 
     
     
         7 . The leaching composition of  claim 1 , wherein the at least one acid is a sulfur-containing acid, selected from the group consisting of sulfuric acid, sodium sulfate, potassium sulfate, rubidium sulfate, cesium sulfate, magnesium sulfate, calcium sulfate, strontium sulfate, barium sulfate, sulfonic acid, sulfonic acid derivatives, and combinations thereof. 
     
     
         8 . (canceled) 
     
     
         9 . The leaching composition of  claim 1 , wherein the composition further comprises at least one of surfactants, defoamers, and combinations thereof. 
     
     
         10 . The leaching composition of  claim 1 , wherein the composition comprises nitric acid, sodium chloride, sulfuric acid, and water. 
     
     
         11 . The leaching composition of  claim 1 , wherein the composition further comprises at least one corrosion inhibitor. 
     
     
         12 . The leaching composition of  claim 1 , wherein the leaching composition is substantially devoid of hydrogen peroxide, fluoride-containing compounds, CuCl 2 , Cl 2 , BrCl 2   − , hydroxide-containing compounds, ferrous ions, a sulfur compound comprising a sulfur atom with an oxidation state in the range of −2 to +5, and cyanides. 
     
     
         13 . A method of removing noble metals from a source, said method comprising contacting said source under conditions with a leaching composition, wherein said noble metals are dissolved or otherwise solubilized in the leaching composition, wherein said leaching composition comprises at least one oxidizing agent, at least one halide, at least one acid, and at least one solvent. 
     
     
         14 . (canceled) 
     
     
         15 . The method of  claim 13 , wherein the source is selected from the group consisting of ores, jewelry, scraps comprising noble metals, waste materials comprising noble metals, electronic waste materials comprising noble metals, alloys, catalyst materials, and industrial sources. 
     
     
         16 . The method of  claim 13 , wherein the source is crushed, cracked, pulverized, shredded, or ground to expose the noble metals. 
     
     
         17 . The method of  claim 13 , wherein the leaching composition and source are agitated such that the source is substantially exposed to the leaching composition. 
     
     
         18 . The method of  claim 13 , wherein the conditions are selected from the group consisting of time of from about 1 min to about 120 minutes, temperature in a range of from about 20° C. to about 100° C., and combinations thereof. 
     
     
         19 . (canceled) 
     
     
         20 . The method of  claim 13 , further comprising reclaiming the noble metals from the leaching composition by electrochemical techniques such as electrowinning, or chemical reduction processes. 
     
     
         21 . The method of  claim 13 , wherein the removal of noble metals from the source is effectuated at temperatures less than about 100° C., pressures not greater than atmospheric pressure, and without the use of electrodes. 
     
     
         22 . The method of  claim 13 , wherein the noble metals comprise a species selected from the group consisting of gold, silver, ruthenium, osmium, rhodium, iridium, palladium, platinum, alloys comprising same, and combinations thereof. 
     
     
         23 . (canceled)