Method for recycling of obsolete printed circuit boards

Abstract

Processes for recycling printed wire boards using environmentally-friendly compositions, wherein electronic components, precious metals and base metals may be collected for reuse and recycling.

1 .- 38 . (canceled) 
     
     
         39 . A method of recovering at least one precious metal from a printed wire board (PWB) comprising solder and at least one precious metal, said method comprising:
 (a) contacting a surface of the PWB with a first composition, wherein the PWB and the first composition are in a first vessel;   (b) agitating said first vessel;   (c) dissolving or solubilizing the solder in the first composition, wherein the first composition selectively removes the solder relative to the at least one precious metal;   (d) removing the first composition from the PWB by rinsing;   (e) drying the PWB;   (f) contacting the PWB with a leaching composition, wherein the PWB and the leaching composition are in a second vessel;   (g) producing agitation in said second vessel;   (h) dissolving or solubilizing the at least one precious metal in the leaching composition;   (i) removing the leaching composition from the PWB by rinsing; and   (j) recovering the at least one precious metal from the leaching composition,   wherein the first composition is:   (i) substantially devoid of fluoride salts, ferric nitrate and other ferric salts, titanium (IV) salts, and abrasive material;   (ii) substantially devoid of fluoride salts, ferric nitrate and other ferric salts, titanium (IV) salts, and fluoroboric acid;   (iii) substantially devoid of fluoride salts, ferric nitrate and other ferric salts, abrasive material, and fluoroboric acid;   (iv) substantially devoid of fluoride salts, titanium (IV) salts, abrasive material, and fluoroboric acid;   (v) substantially devoid of ferric nitrate and other ferric salts, titanium (IV) salts, abrasive material, and fluoroboric acid; or   (vi) substantially devoid of fluoride salts, ferric nitrate and other ferric salts, titanium (IV) salts, abrasive material, and fluoroboric acid.   
     
     
         40 . The method of  claim 39 , wherein at least one component is attached to a surface of the PWB, wherein the at least one component is selected from the group consisting of transistors, capacitors, heat sinks, integrated circuits, resistors, integrated switches, chips, processors, and combinations thereof. 
     
     
         41 . The method of  claim 40 , wherein the at least one component is attached to the surface of the PWB by solder, and wherein the dissolving or solubilizing of the solder in the first composition results in the separation of the at least one component from the PWB. 
     
     
         42 . The method of  claim 39 , wherein the solder comprises lead, tin or a lead/tin alloy. 
     
     
         43 . The method of  claim 39 , wherein the first composition comprises at least one oxidizing agent, nitric acid, and at least one passivating agent, wherein the at least one passivating agent comprises a species selected from the group consisting of ascorbic acid, adenosine, L(+)-ascorbic acid, isoascorbic acid, ascorbic acid derivatives, citric acid, ethylenediamine, gallic acid, oxalic acid, tannic acid, ethylenediaminetetraacetic acid (EDTA), 1,2,4-triazole (TAZ), benzotriazole (BTA), tolyltriazole, 5-phenyl-benzotriazole, 5-nitro-benzotriazole, 3-amino-5-mercapto-1,2,4-triazole, 1-amino-1,2,4-triazole, hydroxybenzotriazole, 2-(5-amino-pentyl)-benzotriazole, 1-amino-1,2,3-triazole, 1-amino-5-methyl-1,2,3-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-isopropyl-1,2,4-triazole, 5-phenylthiol-benzotriazole, halo-benzotriazoles, naphthotriazole 2-mercaptobenzothiazole, 2-mercaptothiazoline, 5-aminotetrazole (ATA), 5-amino-1,3,4-thiadiazole-2-thiol, 2,4-diamino-6-methyl-1,3,5-triazine, thiazole, triazine, methyltetrazole, 1,5-pentamethylenetetrazole, 1-phenyl-5-mercaptotetrazole, diaminomethyltriazine, 4-methyl-4H-1,2,4-triazole-3-thiol, 5-amino-1,3,4-thiadiazole-2-thiol, benzothiazole, tritolyl phosphate, indiazole, benzoic acid, boric acid, malonic acid, ammonium benzoate, catechol, pyrogallol, resorcinol, hydroquinone, cyanuric acid, barbituric acid and derivatives such as 1,2-dimethylbarbituric acid, alpha-keto acids such as pyruvic acid, phosphonic acid and derivatives thereof, glycine/ascorbic acid, Dequest 2000, Dequest 7000, p-tolylthiourea, succinic acid, phosphonobutane tricarboxylic acid (PBTCA), sodium molybdate, ammonium molybdate, sodium chromate, potassium chromate, calcium chromate, barium chromate, sodium tungstate, sodium dichromate, potassium dichromate, ammonium dichromate, suberic acid, azaleic acid, sebacic acid, adipic acid, octamethylene dicarboxylic acid, pimelic acid, dodecane dicarboxylic acid, dimethyl malonic acid, 3,3-diethyl succinic acid, 2,2-dimethyl glutaric acid, 2-methyl adipic acid, trimethyl adipic acid, 1,3-cyclopentane dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid, terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicaroxylic acid, 1,4-naphthalene dicarboxylic acid, 1,4-phenylenedioxy diacetic acid, 1,3-phenylenedioxy diacetic acid, diphenic acid, 4,4′-biphenyl dicarboxylic acid, 4,4′-oxydibenzoic acid, diphenylmethane-4,4′-dicarboxylic acid, diphenylsulfone-4,4′-dicarboxylic acid, decamethylene dicarboxylic acid, undecamethylene dicarboxylic acid, dodecamethylene dicarboxylic acid, orthophthalic acid, naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, trimellitic acid, pyromellitic acid, sodium hexametaphosphate, and combinations thereof. 
     
     
         44 . The method of  claim 39 , wherein the first composition comprises at least one oxidizing agent, nitric acid, and at least one passivating agent, wherein the at least one passivating agent comprises a triazole derivative selected from the group consisting of 1,2,4-triazole, benzotriazole, tolyltriazole, 5-phenyl-benzotriazole, 5-nitro-benzotriazole, 3-amino-5-mercapto-1,2,4-triazole, 1-amino-1,2,4-triazole, hydroxybenzotriazole, 2-(5-amino-pentyl)-benzotriazole, 1-amino-1,2,3-triazole, 1-amino-5-methyl-1,2,3-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-isopropyl-1,2,4-triazole, 5-phenylthiol-benzotriazole, halo-benzotriazoles, naphthotriazole, and 4-methyl-4H-1,2,4-triazole-3-thiol. 
     
     
         45 . The method of  claim 43 , wherein the at least one oxidizing agent comprises ozone, bubbled air, cyclohexylaminosulfonic acid, hydrogen peroxide, oxone, ammonium peroxomonosulfate, ammonium chlorite, ammonium chlorate, ammonium iodate, ammonium perborate, ammonium perchlorate, ammonium periodate, ammonium persulfate, ammonium hypochlorite, sodium persulfate, sodium hypochlorite, potassium iodate, potassium permanganate, potassium persulfate, potassium persulfate, potassium hypochlorite, tetramethylammonium chlorite, tetramethylammonium chlorate, tetramethylammonium iodate, tetramethylammonium perborate, tetramethylammonium perchlorate, tetramethylammonium periodate, tetramethylammonium persulfate, tetrabutylammonium peroxomonosulfate, peroxomonosulfuric acid, urea hydrogen peroxide, peracetic acid, sodium nitrate, potassium nitrate, ammonium nitrate, methanesulfonic acid (MSA), ethanesulfonic acid, 2-hydroxyethanesulfonic acid, n-propanesulfonic acid, isopropanesulfonic acid, isobutenesulfonic acid, n-butanesulfonic acid, n-octanesulfonic acid, benzenesulfonic acid, 4-methoxybenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, 4-aminobenzenesulfonic acid, 4-nitrobenzenesulfonic acid, toluenesulfonic acid, hexylbenzenesulfonic acid, heptylbenzenesulfonic acid, octylbenzenesulfonic acid, nonylbenzenesulfonic acid, decylbenzenesulfonic acid, undecylbenzenesulfonic acid, dodecylbenzenesulfonic acid, tridecylbenzenesulfonic acid, tetradecylbenzene sulfonic acid, hexadecylbenzene sulfonic acid, 3-nitrobenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 2-nitronaphthalenesulfonic acid, 3-nitronaphthalenesulfonic acid, 2,3-dinitrobenzenesulfonic acid, 2,4-dinitrobenzenesulfonic acid, 2,5-dinitrobenzenesulfonic acid, 2,6-dinitrobenzenesulfonic acid, 3,5-dinitrobenzenesulfonic acid, 2,4,6-trinitrobenzenesulfonic acid, 3-aminobenzenesulfonic acid, 2-aminobenzenesulfonic acid, 2-aminonaphthalenesulfonic acid, 3-aminonaphthalenesulfonic acid, 2,3-diaminobenzenesulfonic acid, 2,4-diaminobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid, 2,6-diaminobenzenesulfonic acid, 3,5-diaminobenzenesulfonic acid, 2,4,6-triaminobenzenesulfonic acid, 3-hydroxybenzenesulfonic acid, 2-hydroxybenzenesulfonic acid, 2-hydroxynaphthalenesulfonic acid, 3-hydroxynaphthalenesulfonic acid, 2,3-dihydroxybenzenesulfonic acid, 2,4-dihydroxybenzenesulfonic acid, 2,5-dihydroxybenzenesulfonic acid, 2,6-dihydroxybenzenesulfonic acid, 3,5-dihydroxybenzenesulfonic acid, 2,3,4-trihydroxybenzenesulfonic acid, 2,3,5-trihydroxybenzenesulfonic acid, 2,3,6-trihydroxybenzenesulfonic acid, 2,4,5-trihydroxybenzenesulfonic acid, 2,4,6-trihydroxybenzenesulfonic acid, 3,4,5-trihydroxybenzenesulfonic acid, 2,3,4,5-tetrahydroxybenzenesulfonic acid, 2,3,4,6-tetrahydroxybenzenesulfonic acid, 2,3,5,6-tetrahydroxybenzenesulfonic acid, 2,4,5,6-tetrahydroxybenzenesulfonic acid, 3-methoxybenzenesulfonic acid, 2-methoxybenzenesulfonic acid, 2,3-dimethoxybenzenesulfonic acid, 2,4-dimethoxybenzenesulfonic acid, 2,5-dimethoxybenzenesulfonic acid, 2,6-dimethoxybenzenesulfonic acid, 3,5-dimethoxybenzenesulfonic acid, 2,4,6-trimethoxybenzenesulfonic acid, and combinations thereof. 
     
     
         46 . The method of  claim 43 , wherein the at least one oxidizing agent comprises an alkanesulfonic acid selected from the group consisting of methanesulfonic acid, ethanesulfonic acid, 2-hydroxyethanesulfonic acid, n-propanesulfonic acid, isopropanesulfonic acid, isobutenesulfonic acid, n-butanesulfonic acid, and n-octanesulfonic acid. 
     
     
         47 . The method of  claim 39 , further comprising dissolving at least one base metal using a second composition that selectively dissolves base metal relative to precious metal. 
     
     
         48 . The method of  claim 41 , further comprising contacting the at least one component with the leaching composition to dissolve or solubilize at least one precious metal in the leaching composition. 
     
     
         49 . The method of  claim 39 , wherein the precious metal comprises gold. 
     
     
         50 . The method of  claim 39 , wherein the leaching composition comprises triiodide ions. 
     
     
         51 . The method of  claim 48 , wherein the PWB and/or the at least one component are crushed prior to contact with the leaching composition. 
     
     
         52 . The method of  claim 39 , wherein the precious metal comprises gold and the gold is recovered from the leaching composition using a disproportionation reaction, a reducing agent, or by electrowinning. 
     
     
         53 . The method of  claim 48 , wherein the component is rinsed subsequent to contact with the leaching composition and the rinse water is treated by high surface area electrowinning using an undivided cell, wherein precious metals are plated and iodide is oxidized. 
     
     
         54 . The method of  claim 39 , wherein the leaching composition comprises at least one oxidizing agent, at least one iodide salt or hydroiodic acid, water, and at least one metal passivating agent. 
     
     
         55 . The method of  claim 54 , wherein the at least one oxidizing agent comprises a species selected from the group consisting of oxone, sodium persulfate, ammonium persulfate, potassium persulfate, nitric acid, periodic acid, sodium hypochlorite, hydrogen peroxide, ferric chloride, ferric nitrate, or combinations thereof,
 wherein the at least one iodide salt comprises a species selected from the group consisting of lithium iodide, sodium iodide, potassium iodide, ammonium iodide, calcium iodide, magnesium iodide, and tetraalkylammonium iodides, wherein the alkyl groups may be the same as or different from one another and are selected from the group consisting of straight-chained C 1 -C 6  alkyls and branched C 1 -C 6  alkyls, and   wherein the at least one passivating agent comprises a species selected from the group consisting of benzotriazole, 5-aminotetrazole, 1,2,4-triazole, tolyltriazole, 5-phenyl-benzotriazole, 5-nitro-benzotriazole, 3-amino-5-mercapto-1,2,4-triazole, 1-amino-1,2,4-triazole, hydroxybenzotriazole, 2-(5-amino-pentyl)-benzotriazole, 1-amino-1,2,3-triazole, 1-amino-5-methyl-1,2,3-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-isopropyl-1,2,4-triazole, 5-phenylthiol-benzotriazole, halo-benzotriazoles, naphthotriazole ascorbic acid, sodium molybdate, and combinations thereof.   
     
     
         56 . The method of  claim 39 , wherein the leaching composition is substantially devoid of aqua regia and cyanide-containing components. 
     
     
         57 . The method of  claim 39 , wherein said agitation comprises at least one of mixing, recirculation, turbulence, vibration, or sonication. 
     
     
         58 . The method of  claim 39 , wherein the first composition comprises:
 (i) methanesulfonic acid, nitric acid, benzotriazole and water; (ii) methanesulfonic acid, nitric acid, 1,2,4-triazole and water; (iii) methanesulfonic acid, nitric acid, 1-amino-1,2,4-triazole and water; (iv) methanesulfonic acid, nitric acid, 1-amino-1,2,3-triazole and water; (v) methanesulfonic acid, nitric acid, 1-amino-5-methyl-1,2,3-triazole and water; (vi) methanesulfonic acid, nitric acid, 3-amino-1,2,4-triazole and water; (vii) methanesulfonic acid, nitric acid, 3-mercapto-1,2,4-triazole and water; (viii) methanesulfonic acid, nitric acid, 3-isopropyl-1,2,4-triazole and water; (ix) methanesulfonic acid, nitric acid, 5-aminotetrazole and water; (x) methanesulfonic acid, nitric acid, 2,4-diamino-6-methyl-1,3,5-triazine and water; (xi) methanesulfonic acid, nitric acid, ascorbic acid and water; (xii) methanesulfonic acid, nitric acid, sodium molybdate and water; or (xiiiv) methanesulfonic acid, nitric acid, 3-amino-5-mercapto-1,2,4-triazole and water.   
     
     
         59 . The method of  claim 39 , further comprising flowing the leaching composition through an ion-exchange resin to remove base metals from said composition. 
     
     
         60 . The method of  claim 47 , wherein the at least one base metal comprises nickel, copper, or combinations thereof. 
     
     
         61 . The method of  claim 39 , wherein the PWB comprises a fiberglass layer, copper film, and adhesive. 
     
     
         62 . The method of  claim 61 , wherein the adhesive is degraded to liberate the copper film from the fiberglass layer. 
     
     
         63 . The method of  claim 41 , wherein the at least one component is reusable or recyclable and are separated accordingly.