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.

Description

BACKGROUND[0001]Electronic devices and batteries represent a substantial yearly tonnage of use of metals, metal oxides, plastics, glass, and other materials. Metals of the 3d, 4d, 5d transition series and their oxides are used considerably in these applications. For example, computer monitors can contain lanthanide series oxides used as phosphors coated on the glass surface. Flat panel display devices can contain gold, silver, nickel and platinum in the circuit boards and chips. Also, some electronic devices, such as fluorescent lights, in addition to the phosphor coatings on the interior surface of the glass, contain mercury and therefore cannot lawfully be placed in landfill. Mercury can be toxic if it leaches into groundwater or if it contaminates soil, and has value as a raw material if recovered.[0002]Recovery / recycling (instead of disposal) of electronic devices and spent primary and secondary batteries presents an opportunity for governmental bodies and private industry throu...

AI Technical Summary

Benefits of technology

The invention is a method and system for reclaiming waste, particularly electronic waste, in a profitable manner. The process involves dissolving metals from waste using nitric acid and reclaiming the nitric acid through the use of potassium permanganate. The system can also recycle non-metal components, such as plastic or glass, for further use. The process can be coupled with existing manufacturing processes for zinc phosphate or other chemicals. The invention can also recycle fluorescent lighting tubes by cleaning the glass and precipitating the metal phosphors and mercury. Overall, the invention provides a way to recycle waste and create value through the reclamation of materials.

Problems solved by technology

Electronic devices and batteries represent a substantial yearly tonnage of use of metals, metal oxides, plastics, glass, and other materials.

Also, some electronic devices, such as fluorescent lights, in addition to the phosphor coatings on the interior surface of the glass, contain mercury and therefore cannot lawfully be placed in landfill.

Recovery / recycling (instead of disposal) of electronic devices and spent primary and secondary batteries presents an opportunity for governmental bodies and private industry throughout the world because of the vast amount of waste and the lack of an effective and financially-viable recovery process.

Landfill disposal is increasingly unacceptable not simply because of the loss of valuable metal that could be recovered, but also because of the contamination of soil and ground water due to the leaching of contaminants into the soil or ground water.

Further, as previously mentioned, especially-hazardous materials such as mercury-containing scrap often cannot be disposed in landfills under current law.

Metal sulfates and sulfites themselves are generally not usable and must be converted into metal oxides or carbonates.

Electronic devices, such as computers, computer terminals, radios, VCR players, DVD players, CD players, and cellular telephones, present a somewhat more complex waste issue (all of such devices, other waste electronic devices and waste batteries are collectively referred to herein as “e-waste”) because of the numerous types of devices, the immense physical volume of the devices, the various types of metal used in the various types of devices, and the large volume of each device compared to the amount of metal to be recovered from the device.

This disassembly of e-waste requires a massive amount of manual labor and exposure of workers to toxic metals in the e-waste.

The current methods for recovery also either (1) do not fully reclaim the valuable metal from the e-waste, (2) destroy the inherent high purity of the metal in the e-waste, (3) lead to heavy metals being placed in landfills since low-value components are unprofitable to recycle and are placed in landfills, or (4) (in the case of battery recovery) often result in the use of sulfuric acid, which creates substantial insoluble hazardous by-products, which themselves must usually be further processed into an oxide or carbonate, for reuse.

Images