U.S. patent application number 12/469015 was filed with the patent office on 2009-11-26 for system for recycling printed circuit boards.
Invention is credited to James Carl Dills, Dale B. Halling, Sandra Trott, John S. Wilkes.
Application Number | 20090288956 12/469015 |
Document ID | / |
Family ID | 41341286 |
Filed Date | 2009-11-26 |
United States Patent
Application |
20090288956 |
Kind Code |
A1 |
Dills; James Carl ; et
al. |
November 26, 2009 |
System For Recycling Printed Circuit Boards
Abstract
A process for recycling printed circuit boards includes
pyrolyzing a number printed circuit boards to from an ash. Metals
form the circuit boards are separated from the ash by density
separation techniques. The metals are formed into a slurry
electrode. The slurry electrode and a deposition electrode are
placed in an electrolyte bath and the metals are electrorefined to
form bars of metal. The slurry electrode is made by combining
powderized metals with carbon powder and an ionic liquid to form an
electrode paste. The electrode paste is placed inside a container
with a screen to form the slurry electrode.
Inventors: |
Dills; James Carl;
(Monument, CO) ; Halling; Dale B.; (Colorado
Springs, CO) ; Wilkes; John S.; (Larkspur, CO)
; Trott; Sandra; (Colorado Springs, CO) |
Correspondence
Address: |
LAW OFFICE OF DALE B. HALLING
3595 FOUNTAIN BOULEVARD SUITE A2
COLORADO SPRINGS
CO
80910
US
|
Family ID: |
41341286 |
Appl. No.: |
12/469015 |
Filed: |
May 20, 2009 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61128561 |
May 22, 2008 |
|
|
|
Current U.S.
Class: |
205/348 |
Current CPC
Class: |
H05K 2203/178 20130101;
Y02P 70/613 20151101; C25C 3/34 20130101; C25C 3/00 20130101; Y02P
70/50 20151101; H05K 3/22 20130101; H05K 2203/1136 20130101 |
Class at
Publication: |
205/348 |
International
Class: |
C25C 1/00 20060101
C25C001/00; C25C 7/02 20060101 C25C007/02 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] This invention was made in the performance of a Cooperative
Research and Development Agreement with the Department of the Air
Force. The Government of the United States has certain rights to
use the invention
Claims
1. A process for recycling printed circuit boards, comprising the
steps of: pyrolyzing a plurality of printed circuit boards to form
an ash; separating a plurality of metals from the ash; and
electrorefining the plurality of metals, to form a plurality of
pure metal bars.
2. The process of claim 1, wherein the step of electrorefining
includes the step of creating a slurry electrode.
3. The process of claim 2, wherein the step of creating a slurry
electrode includes mixing the plurality of metal with a carbon
powder to form a electrode powder.
4. The process of claim 3, further including the steps of mixing
the electrode powder with an ionic liquid to form an electrode
paste.
5. The process of claim 4, further including the steps of placing
the electrode paste in an electrode container having a screen.
6. The process of claim 1, wherein the step of electrorefining
includes the steps of creating an ionic liquid of choline chloride
ethylene glycol.
7. The process of claim 1, wherein an anode and a cathode of the
electrorefining step are stacked vertically.
8. A process for electrorefining a plurality of metals comprising
the steps of: combining a plurality of metals in powder form with a
carbon powder to form an electrode powder; mixing the electrode
powder with an ionic liquid to form an electrode paste; placing the
electrode paste in a holder to form a slurry electrode; placing a
deposition electron next to the slurry electrode in an electrolyte
bath; and applying a voltage between the slurry electrode and the
deposition electrode.
9. The process of claim 8, wherein the step of combining the
plurality of metals in powder form includes the step of grinding
the plurality of metals.
10. The process of claim 8, wherein the step of applying the
voltage includes the step of increasing the voltage until a current
exceeds a predetermined threshold.
Description
RELATED APPLICATIONS
[0001] The present invention claims priority on provisional patent
application, Ser. No. 61/128561, filed on May 22, 2008, entitled
"Printed circuit board Recycling Process" and is hereby
incorporated by reference.
THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] Not Applicable
REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM
LISTING
[0004] Not Applicable
BACKGROUND OF THE INVENTION
[0005] The fast pace of product life cycles in the electronics and
computer industry results in large amounts of obsolete electronic
products. These electronic products represent a landfill problem.
These products often have heavy metals that can seep into ground
water and contaminate water supplies. Recent legislation in Europe,
China and several US states now mandate that in the near future
electronics' manufactures must to take back their products at the
end of the products life. In addition, the stringent rules of many
landfills no longer allow these products to be thrown away. One of
the main problems in recycling electrical and electronics products
is the circuit boards. The circuit boards and their components have
most of the heavy metals and may contain lead, mercury, cadmium and
chromium. All of which are being strictly regulated. Presently, the
only way to separate and extract these metals is to expose the
circuit board to high temperatures until the metals vaporize and
then the specific heavy metal can be separated and recovered.
Unfortunately, this process is expensive, requires a tremendous
amount of energy and introduces toxic off gasses into the
atmosphere.
[0006] Thus there exists a need for a process for recycling circuit
boards.
BRIEF SUMMARY OF INVENTION
[0007] A process for recycling printed circuit boards includes
pyrolyzing a number printed circuit boards to from an ash. Metals
from the circuit boards are separated from the ash by density
separation techniques. The metals are formed into a slurry
electrode. The slurry electrode and a deposition electrode are
placed in an electrolyte bath and the metals are electrorefined to
form bars of metal.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0008] FIG. 1 is a block diagram of a process of recycling printed
circuit boards in accordance with one embodiment of the
invention;
[0009] FIG. 2 is a cross sectional view of an electrorefining bath
in accordance with one embodiment of the invention;
[0010] FIG. 3 is a flow chart of the steps used in a process of
recycling printed circuit boards in accordance with one embodiment
of the invention; and
[0011] FIG. 4 is a is a flow chart of the steps used in a process
of electrorefining a group of metals in accordance with one
embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] A process for recycling printed circuit boards includes
pyrolyzing a number printed circuit boards to from an ash. Metals
form the circuit boards are separated from the ash by density
separation techniques. The metals are formed into a slurry
electrode. The slurry electrode and a deposition electrode are
placed in an electrolyte bath and the metals are electrorefined to
form bars of metal.
[0013] FIG. 1 is a block diagram of a process 10 of recycling
printed circuit boards in accordance with one embodiment of the
invention. The process 10 starts with printed circuit boards (PCBs)
12 undergoing pyrolysis 14. The pyrolysis machine 14 requires
energy 16 and has outputs of crude oil 18, and flame retardants 20.
The crude oil 18 can be reused as fuel oil or as feedstock. The
flame retardant 20 can either be disposed of safely or reused. The
carbon 22 can be added to fertilizer or safely land filled. The
other output of the pyrolysis 14 is an ash containing metals and
silica 24 and carbon 22. The ash is ground and density separated
26. The density separation 26 results in silica 28 which may be
sold to a cement plant, carbon which can be safely land filled and
metals 30 in a powdered form. The powdered metals 30 are combined
with an ionic liquid 32 to form a solution 34. The solution 36 then
is electrorefined 38 and results in pure metals 40. In one
embodiment, the ionic liquid may be a choline chloride based ionic
liquid consisting choline chloride and ethylenge glycol in a molar
ratio of 1:2.
[0014] FIG. 2 is a cross sectional view of an electrorefining bath
50 in accordance with one embodiment of the invention. The bath 50
includes a slurry electrode 52 formed from a paste of powderized
metals, carbon powder and an ionic liquid to form an electrode
paste 54. The electrode paste 54 is placed in an electrode,
container having a screen 56. The screen may be a filter paper that
allows ions of the metal to pass freely through the filter paper.
The slurry electrode 52 is placed next to a deposition electrode
58. The deposition electrode 58 is place vertically above the
slurry electrode 52. The electrodes 52, 58 are in electrolytic bath
60 containing an ionic liquid 62 which covers the electrodes 52,
58. A voltage source 62 is connected to the electrodes 52, 58.
[0015] In operation, the slurry electrode will contain many metals,
such as copper, zinc and silver. The deposition electrode will be
formed of the metal that has the lowest oxidation reduction
potential, for example copper. The voltage will be increased until
a current starts to flow. This results in the copper in the slurry
electrode 52 being plated onto the deposition electrode 58. Once
all the copper in the slurry electrode 52 is removed, the copper
deposition electrode will be removed. Next a zinc electrode will be
used as the deposition electrode. This is because the oxidation
reduction potential of zinc is less than that of silver. The
voltage is increased until current starts to flow. This results in
the zinc in the slurry electrode being plated onto the deposition
electrode 58. Once all the zinc is removed, the process is repeated
for the silver using a silver electrode.
[0016] FIG. 3 is a flow chart of the steps used in a process of
recycling printed circuit boards in accordance with one embodiment
of the invention. The process starts, step 70, by pyrolyzing the
plurality of printed circuit boards to form an ash, step 72. The
metals are separated from the ash at step 74. At step 76 the metals
are electrorefined to form pure metal bars at step 78.
[0017] FIG. 4 is a is a flow chart of the steps used in a process
of electrorefining a group of metals in accordance with one
embodiment of the invention. The process starts, step 90, by
combining metal powders with carbon powder to form an electrode
powder at step 92. The electrode powder is mixed with an ionic
liquid to form an electrode paste at step 94. The electrode paste
is placed in a holder to form a slurry electrode at step 96. A
deposition electrode is placed next to the slurry electrode in an
electrolytic bath at step 98. At step 100, a voltage is applied
between the slurry electrode and the deposition electrode, which
ends the process at step 102.
[0018] While the invention has been described in conjunction with
specific embodiments thereof, it is evident that many alterations,
modifications, and variations will be apparent to those skilled in
the art in light of the foregoing description. Accordingly, it is
intended to embrace all such alterations, modifications, and
variations in the appended claims.
* * * * *