Oxygen torch reclamation of metals with nitric acid recovery

Abstract

Disclosed is a system for removing metals from waste, particularly electronic waste (or “e-waste”). The process generally includes the steps of dissolving at least some of the metals from the wastein a nitric acid bath and then causing at least some of the metals to precipitate as metal oxides and/or metal nitrates. The system can include multiple tanks or locations for dissolving metals and/or precipitating metals, preferably as metal oxides or metal nitrates. The process and system reclaim more preferably NOx gas for the regeneration of nitric acid, which is recycled for use in the metal reclamation system.

1 - 109 . (canceled) 
     
     
         110 . A system for removing metal from waste, the system comprising (a) a first tank in which the waste is placed and at least some of the metal from the waste is dissolved to create a solution, and (ii) a second tank in fluid communication with the first tank and in which at least some of the metal that is dissolved is precipitated as one or more of the group consisting of a metal oxide and a metal nitrate. 
     
     
         111 . The system of  claim 110  wherein the pH of solution containing dissolved metal is increased by adding KOH to the second tank in order to precipitate the metal. 
     
     
         112 . The method of  claim 111  wherein the KOH is added to the solution by adding discarded batteries to the solution that include KOH. 
     
     
         113 . The system of  claim 110  wherein the waste includes more than one metal and wherein all of the metals go into solution. 
     
     
         114 . The system of any of  claim 110  wherein the metal is selected from one or more of the group consisting of: silver, platinum, copper, zinc, tin, iron, mercury, antimony, arsenic, calcium, nickel, cadmium, beryllium, rhodium, palladium, lead, aluminum, magnesium, manganese, indium and iridium. 
     
     
         115 . The system of  claim 110  wherein at least one metal is precipitated as an elemental metal and wherein the metal that is precipitated as an elemental metal is selected from one or more of the group consisting of copper, silver, gold and platinum. 
     
     
         116 . The system of  claim 110  wherein the pH of the solution is increased to precipitate the metal by adding to the second tank one or more of the group consisting of: ammonia, zinc oxide, potassium carbonate, and (NH 4 ) 2  CO 3 . 
     
     
         117 . The system of  claim 110  wherein zinc oxide is added to the second tank to increase the PH of the solution by adding waste alkaline batteries that include zinc oxide. 
     
     
         118 . The system of  claim 110  wherein the solution includes a plurality of metals that are dissolved and each of the metals is precipitated from solution by progressively increasing the pH of the nitric acid bath in the second tank and removing each metal individually when it precipitates. 
     
     
         119 . The system of  claim 111  wherein a by-product of adding potassium hydroxide to the nitric acid bath is potassium nitrate. 
     
     
         120 . The system of  claim 110  wherein the waste is one or more of the group consisting of: batteries, lap-top computers, fluorescent light bulbs, cameras, desk-top computers, television, DVD players, cell phones, CD players and radios. 
     
     
         121 . The system of  claim 110  wherein there are multiple tanks for precipitating metal from the solution. 
     
     
         122 . The system of  claim 121  wherein different metals are precipitated from each of the multiple tanks for precipitating metal. 
     
     
         123 . The system of  claim 110  wherein NO x  gas is produced as a by product. 
     
     
         124 . The system of  claim 123  wherein the NO x  gas is captured using a hood positioned over one or more of the tanks. 
     
     
         125 . The system of  claim 124  wherein the NO x  gas is moved into a reaction zone. 
     
     
         126 . The system of  claim 125  wherein the NO x  gas is preheated before being moved into the reaction zone. 
     
     
         127 . The system of  claim 126  wherein the NO x  gas is preheated to about 500° F. before being moved into the reaction zone. 
     
     
         128 . The system of  claim 125  wherein oxygen is moved into the reaction zone and is present in the reaction zone when NO x  is present. 
     
     
         129 . The system of  claim 128  wherein the reaction zone has an entrance where the NO x  gas enters and an exit, and the pressure at the entrance is greater than the pressure at the exit. 
     
     
         130 . The system of  claim 128  wherein the reaction zone includes an igniter that ignites the oxygen. 
     
     
         131 . The system of  claim 130  wherein the igniter is one or more of the group selected from an electric heater and a gas flame. 
     
     
         132 . The system of  claim 130  wherein about 90% or more of the NO x  gas is converted to NO 2  gas that exits the reaction zone. 
     
     
         133 . The system of  claim 132  wherein the gas exiting the reaction zone goes to a quench vessel where water is mixed with the gas and at least part of the NO 2  gas is converted to HNO 3 . 
     
     
         134 . The system of  claim 133  wherein at least some of the gas present in the gas exiting the reaction zone is H 2 S which is at least partially converted to H 2 SO 4  in the quench vessel. 
     
     
         135 . The system of  claim 133  wherein the HNO 3  is recycled into the first tank.