U.S. patent application number 12/007153 was filed with the patent office on 2010-11-04 for method for recycling precious metal from used printed circuit boards.
This patent application is currently assigned to ATOMIC ENERGY COUNCIL - INSTITUTE OF NUCLEAR ENERGY RESEARCH. Invention is credited to Ching-Liang Chen, Hei-Yi Chen, Yun-Hua Chen, Ching-Hwa Lee, Wen-Cheng Lee, Fu-Jen Yeh.
Application Number | 20100275730 12/007153 |
Document ID | / |
Family ID | 43029398 |
Filed Date | 2010-11-04 |
United States Patent
Application |
20100275730 |
Kind Code |
A1 |
Lee; Wen-Cheng ; et
al. |
November 4, 2010 |
Method for recycling precious metal from used printed circuit
boards
Abstract
A method is disclosed for recycling precious metal from used
printed circuit boards. The used printed circuit boards are roasted
with plasma at 800 degrees Celsius for less than 10 minutes, thus
producing exhaust and residue that contains the precious metal. The
exhaust is treated with an exhaust-treatment system before it is
released to the atmosphere. The residue is ground and turned into
scraps of a diameter smaller than 2 mm. The scraps are subjected to
magnetic separation, thus separating ferromagnetic scraps from
non-ferromagnetic scraps. The ferromagnetic scraps are refined. The
non-ferromagnetic scraps are screened, thus separating tiny
non-ferromagnetic scraps from big non-ferromagnetic scraps. The
tiny non-ferromagnetic scraps contain silver and gold. The big
non-ferromagnetic scraps contain copper.
Inventors: |
Lee; Wen-Cheng; (Bade City,
TW) ; Lee; Ching-Hwa; (Dah-Tsuen Township, TW)
; Chen; Ching-Liang; (Taoyuan City, TW) ; Yeh;
Fu-Jen; (Longtan Township, TW) ; Chen; Hei-Yi;
(Dah-Tsuen Township, TW) ; Chen; Yun-Hua;
(Dah-Tsuen Township, TW) |
Correspondence
Address: |
Jackson Intellectual Property Group PLLC
106 Starvale Lane
Shipman
VA
22971
US
|
Assignee: |
ATOMIC ENERGY COUNCIL - INSTITUTE
OF NUCLEAR ENERGY RESEARCH
Taoyuan
TW
|
Family ID: |
43029398 |
Appl. No.: |
12/007153 |
Filed: |
January 7, 2008 |
Current U.S.
Class: |
75/403 |
Current CPC
Class: |
C22B 1/02 20130101; Y02P
10/214 20151101; C22B 7/001 20130101; C22B 11/025 20130101; Y02P
10/20 20151101; C22B 7/005 20130101 |
Class at
Publication: |
75/403 |
International
Class: |
C22B 1/00 20060101
C22B001/00 |
Claims
1. A method for recycling precious metal from used printed circuit
boards, the method comprising the steps of: roasting the used
printed circuit boards with plasma at 800 degrees Celsius for less
than 10 minutes, thus producing exhaust and residue that contains
the precious metal; treating the exhaust with an exhaust-treatment
system before releasing it to the atmosphere; grinding the residue
and turning it into scraps of a diameter smaller than mm;
subjecting the scraps to magnetic separation, thus separating
ferromagnetic scraps from non-ferromagnetic scraps; refining the
ferromagnetic scraps; screening the non-ferromagnetic scraps, thus
separating tiny non-ferromagnetic scraps from big non-ferromagnetic
scraps, wherein the tiny non-ferromagnetic scraps contain silver
and gold, while the big non-ferromagnetic scraps contain
copper.
2. The method according to claim 1, wherein the tiny
non-ferromagnetic scraps are smaller than 0.149 mm in diameter.
3. The method according to claim 1, wherein the big
non-ferromagnetic scraps 72 are larger than 0.149 mm in diameter.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to printed circuit boards and,
more particularly, to a method for recycling precious metal from
used printed circuit boards.
DESCRIPTION OF THE RELATED ARTS
[0002] Printed circuit boards contain precious metal such as gold,
silver and copper. It is not only environmentally hazardous but
also economically wasteful to dispose of used printed circuit
boards without recycling the precious metal.
[0003] As disclosed in Taiwanese Patent Publication Nos. 247281 and
363904, used printed circuit boards are smashed before precious
metal such as the gold, silver and copper is recycled. It, however,
requires a lot of energy to smash the used printed circuit boards
since they are composed of mainly elastic resin. Moreover, a lot of
dust and noise are made. In addition to these drawbacks, machines
for smashing the used printed circuit boards wear away
substantially.
[0004] As disclosed in Taiwanese Patent Publication 1268184, used
printed circuit boards are incinerated before precious metal such
as the gold, silver and copper is recycled. It, however, requires a
lot of energy and takes a lot of time to incinerate the used
printed circuit boards.
[0005] The present invention is therefore intended to obviate or at
least alleviate the problems encountered in prior art.
SUMMARY OF THE INVENTION
[0006] The primary objective of the present invention is to provide
a method for recycling precious metal from used printed circuit
boards.
[0007] To achieve the foregoing objective of the present invention,
in a method, used printed circuit boards are roasted with plasma at
800 degrees Celsius for less than 10 minutes, thus producing
exhaust and residue that contains the precious metal. The exhaust
is treated with an exhaust-treatment system before it is released
to the atmosphere. The residue is ground and turned into scraps of
a diameter smaller than 2 mm. The scraps are subjected to magnetic
separation, thus separating ferromagnetic scraps from
non-ferromagnetic scraps. The ferromagnetic scraps are refined. The
non-ferromagnetic scraps are screened, thus separating tiny
non-ferromagnetic scraps from big non-ferromagnetic scraps. The
tiny non-ferromagnetic scraps contain silver and gold. The big
non-ferromagnetic scraps contain copper.
[0008] Other objectives, advantages and features of the present
invention will become apparent from the following description
referring to the attached drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention will be described via detailed
illustration of the preferred embodiment referring to the attached
drawing.
[0010] FIG. 1 is a flowchart of a method for recycling precious
metal from used printed circuit boards according to the preferred
embodiment of the present invention.
DETAILED DESCRIPTION OF EMBODIMENT
[0011] Referring to FIG. 1, there is shown a method for recycling
precious metal from used printed circuit boards according to the
preferred embodiment of the present invention.
[0012] At 1, used printed circuit boards are collected.
[0013] At 2, the used printed circuit boards are roasted with
plasma so that the resin in the used printed circuit boards is
decomposed. The plasma-based roasting is conducted at a temperature
of 800 degrees Celsius for a period of 10 minutes. Exhaust 21 is
produced as a byproduct. The residue 22 left as the result of the
plasma-based roasting contains the precious metal and glass
fibers.
[0014] AT 3, the exhaust 21 produced because of the plasma-based
roasting is treated with an exhaust-treatment system, and
hereinafter released to the atmosphere.
[0015] At 4, the residue 22 is ground into scraps 41 of a diameter
smaller than 2 mm.
[0016] At 5, the ground scraps 41 are subjected to magnetic
separation so that ferromagnetic scraps 51 are separated from
non-ferromagnetic scraps 52.
[0017] At 6, the ferromagnetic scraps 51 are refined in an iron
refinery.
[0018] At 7, the non-ferromagnetic scraps 52 are sifted by a screen
with meshes of 0.149 mm in diameter. Therefore, tiny
non-ferromagnetic scraps 71 are separated from big
non-ferromagnetic scraps 72. The tiny non-ferromagnetic scraps 71
that contain gold and silver are smaller than 0.149 mm in diameter.
The big non-ferromagnetic scraps 72 that contain copper are larger
than 0.149 mm in diameter.
[0019] At 8, the tiny non-ferromagnetic scraps 71 are processed in
a precious metal refinery so that the gold and silver are
recycled.
[0020] At 9, the big non-ferromagnetic scraps 72 are processed in a
copper smelter so that the copper is recycled.
[0021] The method according to the present invention exhibits
several advantages over the methods discussed in the RELATED PRIOR
ART. The resin of the used printed circuit boards is roasted and
decomposed with the plasma. Therefore, the first advantage is the
relatively low energy needed to grind the residue 22.
[0022] Secondly, the wearing out of grinding machines is
reduced.
[0023] Thirdly, it is relatively friendly to the atmosphere because
the exhaust 21 is treated before it is released.
[0024] Fourthly, it is economically worthwhile for recycling the
precious metal such as gold, silver, copper and iron.
[0025] Fifthly, it is relatively friendly to the environment
because relatively little material is disposed of as waste.
[0026] Sixthly, it is safe.
[0027] The present invention has been described via the detailed
illustration of the preferred embodiment. Those skilled in the art
can derive variations from the preferred embodiment without
departing from the scope of the present invention. Therefore, the
preferred embodiment shall not limit the scope of the present
invention defined in the claims.
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