U.S. patent application number 10/550492 was filed with the patent office on 2006-08-31 for method and devices for recycling copper from a discarded circuit board and a discarded fluid containing copper.
Invention is credited to Hsieh Sen Wu.
Application Number | 20060191376 10/550492 |
Document ID | / |
Family ID | 36930862 |
Filed Date | 2006-08-31 |
United States Patent
Application |
20060191376 |
Kind Code |
A1 |
Wu; Hsieh Sen |
August 31, 2006 |
Method and devices for recycling copper from a discarded circuit
board and a discarded fluid containing copper
Abstract
An eco-friendly method is designed to recycle copper contained
in the discarded printed circuit boards and the like. The method
involves use of various acids, such as hydrochloric acid, sulphuric
acid, oxalic acid, to bring about the ionization of the copper,
thereby resulting in formation of copper-containing solutions. The
copper is brought back in the form of copper oxide or copper powder
by use of various reducing agents. All byproducts produced in the
course of recycling the copper are useful for other industrial
applications.
Inventors: |
Wu; Hsieh Sen; (Taipei,
TW) |
Correspondence
Address: |
BACON & THOMAS, PLLC
625 SLATERS LANE
FOURTH FLOOR
ALEXANDRIA
VA
22314
US
|
Family ID: |
36930862 |
Appl. No.: |
10/550492 |
Filed: |
March 27, 2003 |
PCT Filed: |
March 27, 2003 |
PCT NO: |
PCT/US03/08459 |
371 Date: |
September 26, 2005 |
Current U.S.
Class: |
75/353 ; 266/170;
75/714 |
Current CPC
Class: |
C22B 15/00 20130101;
Y02P 10/236 20151101; Y02P 10/234 20151101; C22B 15/0084 20130101;
C22B 7/007 20130101; Y02P 10/20 20151101 |
Class at
Publication: |
075/353 ;
075/714; 266/170 |
International
Class: |
C22B 15/00 20060101
C22B015/00 |
Claims
1. A method for recycling copper contained in the discarded printed
circuit boards, said method comprising the following steps of: (a)
ionizing the copper contained in the discarded printed circuit
boards by immersing the discarded printed circuit board in
hydrochloric acid (HCl), so as to form a copper chloride
(CuCl.sub.2) solution; (b) adding sodium carbonate
(Na.sub.2CO.sub.3) into the copper chloride solution, thereby
resulting in formation of copper carbonate (CUCO.sub.3) and sodium
chloride (NaCl); and (c) converting the copper carbonate by heating
into copper oxide (CuO).
2. A method, as recited in claim 1, wherein said hydrochloric acid
may use an electroplating waste fluid, etching waste fluid, or
copper chloride waste fluid, which is a waste product of the
manufacturing process of PCB.
3. A method for recycling copper contained in the discarded printed
circuit boards, said method comprising the following steps of: (a)
ionizing the copper contained in the discarded printed circuit
boards by immersing the discarded printed circuit boards in
hydrochloric acid (HCl), so as to form a copper chloride
(CuCl.sub.2) solution; (b) adding sodium hydroxide (NaOH) into the
copper chloride solution, thereby resulting in formation of copper
hydroxide, Cu(OH).sub.2, and sodium chloride, NaCl; and (c)
converting the copper hydroxide by heating into copper oxide
(CuO).
4. A method, as recited in claim 3, wherein said hydrochloric acid
may use an electroplating waste fluid, etching waste fluid, or
copper chloride waste fluid, which is a waste product of the
manufacturing process of PCB.
5. A method for recycling copper contained in the discarded printed
circuit boards, said method comprising the following steps of: (a)
ionizing the copper contained in the discarded printed circuit
boards by immersing the discarded printed circuit boards in
sulphuric acid (H.sub.2SO.sub.4), so as to form a copper sulphate
(CuSO.sub.4) solution; (b) adding sodium carbonate
(Na.sub.2CO.sub.3) into the copper sulphate solution, thereby
resulting in formation of copper carbonate (CUCO.sub.3) and sodium
sulphate (Na.sub.2 SO.sub.4); and (c) converting the copper
carbonate by heating into copper oxide (CuO).
6. A method, as recited in claim 5, wherein said sulphuric acid may
use an electroplating waste fluid, etching waste fluid, or copper
chloride waste fluid, which is a waste product of the manufacturing
process of PCB.
7. A method for recycling copper contained in the discarded printed
circuit bards, said method comprising the following steps of: (a)
ionizing the copper contained in the discarded printed circuit
boards by immersing the discarded printed circuit boards in
sulphuric acid (H.sub.2SO.sub.4), so as to form a copper sulphate
(CuSO.sub.4) solution; (b) adding sodium hydroxide (NaOH) into the
copper sulphate solution, thereby resulting in formation of copper
hydroxide, Cu(OH).sub.2, and sodium sulphate, Na.sub.2SO.sub.4; and
(c) converting the copper hydroxide by heating into copper oxide
(CuO).
8. A method, as recited in claim 7, wherein said sulphuric acid may
use an electroplating waste fluid, etching waste fluid, or copper
chloride waste fluid, which is a waste product of the manufacturing
process of PCB.
9. A method for recycling copper contained in the discarded printed
circuit boards, said method comprising the following steps of: (a)
immersing the discarded printed circuit boards in an oxalic acid
(HOOCCOOH-2H.sub.2O) solution, thereby resulting in formation of
copper oxalate (CuC.sub.2O.sub.4-1/2H.sub.2O); and (b) converting
the copper oxalate by heating in presence of oxygen into copper
oxide (CuO).
10. A method for recycling copper contained in the discarded
printed circuit boards, said method comprising the following stops
of: (a) ionizing the copper contained in the discarded printed
circuit boards by immersing the discarded printed circuit boards in
hydrochloric acid (HCl), so as to form a copper chloride
(CuCl.sub.2) solution; and (b)adding an aluminium material into the
copper chloride solution, thereby resulting in formation of copper
powder and an aqueous solution of poly aluminium chloride
[Al.sub.2(OH).sub.nCl.sub.6-n.XH.sub.2O]m.
11. A method for recycling copper contained in the discarded
printed circuit boards, said method comprising the following steps
of: (a) ionizing the copper contained in the discarded printed
circuit boards by immersing the discarded printed circuit boards in
sulphuric acid (H.sub.2SO.sub.4), so as to form a copper sulphate
(CuSO.sub.4) solution; and (b) adding an aluminium material into
the copper sulphate solution, thereby resulting in formation of
copper powder, and an aluminium sulphate aqueous solution,
Al.sub.2[SO.sub.4].sub.3.
12. A device used to recycle copper contained in the discarded
printed circuit boards, said device comprising: a reaction tank
having an acid exit in the wall; a precipitation bath having an
acid inlet in the wall, an outlet, and a discharge port of sodium
salt, wherein the acid inlet is connected with the acid exit of the
reaction tank by a connection pipe which is provided with a valve.
And said precipitation bath is provided with an electric agitator;
a conversion oven having a feeding port which is located at the top
of the conversion oven and a discharging port which is located at
the bottom of the conversion oven; and a heater, which is disposed
in the interior of the conversion oven and provided the temperature
of the interior of the conversion oven to kept between 230.degree.
C. and 350.degree. C.
13. A device, as recited in claim 12, wherein said conversion oven
further comprises a feeding controller, a see-through window, an
isolation tank, and a dust remover. wherein said feeding controller
is disposed under the feeding port for controlling the feeding
speed. Said see-through window is located in the wall of the
conversion oven to facilitate the visual observation of the process
in progress. Said isolation tank is disposed on the discharging
port for preventing copper oxide (CuO) from being contaminated in
the course of transfer of the copper oxide. Said dust remover
comprises a dust collecting tube, a water bath, and a venture tube
dust cleaner. Said dust collecting tube is connected to the wall of
the conversion oven. Said venture tube dust cleaner is mounted on
the tube wall of the dust collecting tube. A water pipe is
connected with the venture tube dust cleaner and the water bath.
The water pipe is provided with a pump.
14. A device, as recited in claim 12, wherein said heater is
located at the bottom of the conversion oven.
15. A device used to recycle copper contained in the discarded
printed circuit boards, said device comprising: a reactor; a acid
reservoir, which is connected with the reactor by a pipe which is
provided with a valve, and said acid reservoir is provided in the
wall with a solution transporting pipe which is in turn provided
with a pump; a PAC reaction precipitation bath having a basket for
holding aluminium. which is located at the top of PAC reaction
precipitation bath and a copper powder exit. The precipitation bath
is further provided in the wall with a reaction circulation pipe,
which is provided with a reaction circulation pump and a reaction
circulation valve. The reaction circulation pipe has one end which
is located at the top of the basket. A PAC drain pipe is disposed
on the reaction circulation pipe located between the reaction
circulation pump and the reaction circulation valve. The PAC drain
pipe is provided with a PAC output valve. The pipe of said solution
transporting pipe has one end which is extended into the PAC
reaction precipitation bath; and a water tower, which is provided
in the wall with a water pipe which is provided with a reaction
water admission valve and has one end being extended into the PAC
reaction precipitation bath.
16. A device, as recited in claim 15, further comprises a PAC
washing and storing apparatus having a washing and filtering tank
and a PAC storage tank. Wherein the washing and filtering tank is
provided at the top with a filter and is provided in the wall with
a PAC output pipe which is provided with a pump. The top of the
washing and filtering tank is connected with a PAC filtration pipe.
a PAC storage pipe and a return pipe. The PAC filtration pipe, the
PAC storage pipe, and the return pipe are all connected with the
PAC output pipe and are provided with a valve. The filter and the
water tower are connected by a washing pipe which is provided with
a valve.
Description
FIELD OF THE PRESENT INVENTION
[0001] The present invention relates generally to a process for
recycling copper from a substance containing the copper, and more
particularly to the methods and the devices by which the copper is
completely recycled from a discarded printed circuit board (PCB)
and from a discarded fluid containing the copper.
BACKGROUND OF THE PRESENT INVENTION
[0002] As a result of the rapid development of information
technology in recent years, the use of the low-end computers as
well as the hand sets is wide-spread. Such a wide-spread use of the
computers and the hand sets brings about a substantial increase in
demand for the printed circuit board. Accordingly, the discarded
printed circuit boards pose an environmental problem. In light of
the fact that the process for making PCB involves the use of a
chemical etching solution, such as copper chloride or the like. As
a result, the process for making PCB results in production of a
discarded fluid containing an extremely high concentration of
copper ions. Without being properly treated, the discard fluid
poses a potential environmental hazard. In addition, the copper
which is contained in the discarded fluid should be recycled as a
matter of cost-effectiveness. It is therefore imperative that
copper should be recycled from a discarded or rejected PCB for
economic and environmental reasons. A number of electronic
components are attached to the PCB by tin soldering. The tin can be
easily recycled by use of a stripping fluid. However, the copper
contained in the discarded or rejected PCB can not be easily
recycled by use of a stripping fluid. There are two conventional
methods, by which the copper contained in the discarded PCB is
recycled. These two conventional methods are described
hereinafter.
[0003] The first conventional method involves the comminution of
the discarded printed circuit boards. By virtue of the principle of
specific gravity, the powder is divided into two groups, one of
which contains a greater amount of copper. This method is rather
primitive and ineffective at best.
[0004] The second conventional method involves the burning of the
glass fiber and the adhesive of the discarded printed circuit
boards. The adhesive contains epoxy resin and bromide. As a result.
the burning of the adhesive is bound to produce bromine hydride
which is a pollutant. In addition, the burning of the glass fiber
must be done at a temperature greater than 1000 degress in Celsius
and is therefore not cost-effective.
SUMMARY OF THE PRESENT INVENTION
[0005] The primary objective of the present invention is to provide
an economically feasible method for recycling copper that is
contained in the discarded printed circuit boards or the discarded
fluid which is resulted from the electroplating process or the
etching process of the PCB production. The method involves the
saturation of copper ions, which are then reduced by use of sodium
carbonate or sodium hydroxide.
[0006] Another objective of the present invention is to provide a
copper recycling method, which involves use of hydrochloric acid.
The discarded printed circuit boards are showered with the
hydrochloric acid to obtain a fluid containing copper. The
copper-containing fluid is provided with sodium carbonate, thereby
resulting in formation of sodium salt and copper carbonate. The
sodium salt can be crystallized by heating for industrial
application. The copper carbonate is converted by heating into
copper oxide, which is sold to generate an additional income. This
method is economical and free from a pollutant.
[0007] Another objective of the present invention is to provide a
method for recycling copper which is contained in the discarded
printed circuit boards. The method involves the use of hydrochloric
acid or sulphuric acid, by which the copper is ionized in a
solution. The solution is then provided with sodium hydroxide to
form sodium salt and copper hydroxide. The copper hydroxide is
converted by heating into copper oxide, which can be used as an
industrial material. Meanwhile, the sodium salt is crystallized by
heating for industrial application.
[0008] Another objective of the present invention is to provide a
copper recycling process in which the discarded printed circuit
boards are bathed in a solution containing oxalic acid
(HOOCCOOH-1/2H.sub.2O). The copper contained in the discarded
printed circuit boards is made into copper oxalate
(CuC.sub.2O.sub.4-1/2H.sub.2O), which is precipitated and
harvested. The copper oxalate is heated in presence of oxygen so as
to be converted into copper oxide which is of a commercial
value.
[0009] A further objective of the present invention is to provide a
process for recycling copper that is contained in the discarded
printed circuit boards. The process involves the use of
hydrochloric acid or sulphuric acid, in which the discarded printed
circuit boards are bathed to produce a solution containing the
copper ions. An aluminum material is then introduced into the
solution to result in formation of copper powder. The
aluminum-containing solution can be used as PAC in the water
treatment. The aluminum is used in the process by virtue of the
aluminum being greater in activity than the copper.
BRIEF DESCRIPTION OF THE DRAWING
[0010] FIG. 1 shows a flow block diagram of a first preferred
embodiment of the present invention.
[0011] FIG. 2 shows a flow block diagram of a second preferred
embodiment of the present invention.
[0012] FIG. 3 shows a flow diagram of a third preferred embodiment
of the present invention.
[0013] FIG. 4 shows a flow block diagram of a fourth preferred
embodiment of the present invention.
[0014] FIG. 5 shows a flow block diagram of a fifth preferred
embodiment of the present invention.
[0015] FIG. 6 shows a schematic view of a device which is used in
the preferred embodiments as shown in FIG. 1 through FIG. 5.
[0016] FIG. 7 shows a flow block diagram of a sixth preferred
embodiment of the present invention.
[0017] FIG. 8 shows a flow block diagram of a seventh preferred
embodiment of the present invention.
[0018] FIG. 9 shows a schematic view of a device which is used in
the preferred embodiments as shown in FIG. 7and FIG. 8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] It must be noted here that the present invention deals with
the recycling of the copper that is contained in a discarded
printed circuit board (PCB). Accordingly, the electronic components
of the PCB and the tin solder, by which the electronic components
are attached to the PCB, are not the subject matters of the present
invention.
[0020] Referring to FIG. 1, a method embodied in the present
invention is used to recycle copper from the discarded printed
circuit boards. The method involves a first step in which a
predetermined number of the discarded printed circuit boards are
immersed in the hydrochloric acid (HCl) so as to cause copper
contained in the discarded printed circuit boards to remain in the
ionizing state, thereby resulting in formation of a copper chloride
(CuCl.sub.2) solution. The chemical reaction is expressed as
follows: Cu+2HCl.fwdarw.CuCl.sub.2+H.sub.2.uparw.
[0021] Thereafter, the copper chloride (CuCl.sub.2) solution is
mixed with a predetermined amount of sodium carbonate
(Na.sub.2CO.sub.3), as illustrated by the following chemical
reaction:
CuCl.sub.2+Na.sub.2CO.sub.3.fwdarw.CuCO.sub.3.dwnarw.+2NaCl
[0022] The copper carbonate (CuCO.sub.3) is precipitated and
harvested. The copper carbonate is converted by heating into copper
oxide (CuO), as shown in the following chemical reaction.
##STR1##
[0023] The copper oxide is used as an industrial raw material. The
sodium chloride (NaCl) is also used as an industrial raw material.
However, the sodium chloride so formed must be first crystallized
by heating prior to being used as the industrial raw material.
[0024] The use of the hydrochloric acid is to effect the ionization
of the copper that is contained in the discarded printed circuit
boards. The copper ionization can be enhanced by use of hydrogen
peroxide, aeration, or electrode. The reduction of the copper ions
is brought about by use of sodium carbonate (Na.sub.2CO.sub.3).
[0025] It must be noted here that the hydrochloric acid may be
replaced by an electroplating waste fluid, etching waste fluid, or
copper chloride waste fluid, which is a waste product of the
manufacturing process of PCB. These waste fluids contain copper, as
well as ionizing acid capable of ionizing the copper. The copper
ions are then reduced by sodium carbonate (Na2CO.sub.3), thereby
resulting in formation of copper carbonate (CuCO.sub.3), which is
then converted by heating into copper oxide (CuO).
[0026] As shown in FIG. 2, a second method embodied in the present
invention is intended to recycle copper from the discarded printed
circuit boards. This second method comprises an initial step in
which the discarded printed circuit boards are immersed in the
hydrochloric acid (HCl) so as to form a copper chloride
(CuCl.sub.2) solution, as illustrated by the following chemical
equation. Cu+2HCl.fwdarw.CuCl.sub.2+H2.uparw.
[0027] The copper chloride solution is then mixed with sodium
hydroxide (NaOH) to form copper hydroxide, Cu(OH).sub.2, and sodium
chloride (NaCl), as shown in the following reaction equation.
CuCl.sub.2+2NaOH Cu(OH).sub.2.dwnarw.+2NaCl
[0028] The copper hydroxide is precipitated and harvested; it is
then converted by heating into copper oxide as shown in the
following chemical equation. ##STR2##
[0029] The sodium chloride is crystallized by heating before it is
used as an industrial raw material. The copper oxide can be used
directly as an industrial raw material. It must be noted here that
the ionization of copper by the hydrochioric acid can be
accelerated by use of hydrogen peroxide, aeration, or
electrode.
[0030] It must be noted here that the hydrochloric acid may be
replaced by an electroplating waste fluid, etching waste fluid, or
copper chloride waste fluid, which is a waste product of the
manufacturing process of PCB. These waste fluids contain copper, as
well as ionizing acid capable of ionizing the copper. The copper
ions are then reduced by sodium hydroxide (NaOH), thereby resulting
in formation of copper carbonate (CuCO.sub.3), which is then
converted by heating into copper oxide(CuO).
[0031] Referring to FIG. 3, a third method embodied in the present
invention is designed to recycle copper from the discarded printed
circuit boards. In the first place, the discarded printed circuit
boards are immersed in the sulphuric acid (H.sub.2SO.sub.4),
thereby resulting in formation of copper sulphate (CuSO.sub.4) as
shown in the following chemical equation.
Cu+H.sub.2SO.sub.4=CuSO.sub.4+H.sub.2.uparw.
[0032] A reducing agent, sodium carbonate (Na.sub.2CO.sub.3), is
added to the copper sulphate solution, thereby resulting in
formation of copper carbonate (CuCO.sub.3) and sodium sulphate
(Na.sub.2SO.sub.4) as shown in the following chemical reaction.
CuSO.sub.4+Na.sub.2CO.sub.3.fwdarw.CuCO.sub.3.dwnarw.+Na.sub.2SO.sub.4
[0033] The copper carbonate is precipitated and harvested; it is
then converted by heating into copper oxide (CuO), which is used as
an industrial raw material. ##STR3##
[0034] The ionization of copper by sulphuric acid can be enhanced
by use of hydrogen peroxide, aeration, or electrode. The byproduct,
such as sodium sulphate (Na.sub.2SO.sub.4), is crystallized by
heating prior to being used as an industrial raw material.
[0035] It must be noted here that the hydrochloric acid may be
replaced by an electroplating waste fluid, etching waste fluid, or
copper chloride waste fluid, which is a waste product of the
manufacturing process of PCB. These waste fluids contain copper, as
well as ionizing acid capable of ionizing the copper. The copper
ions are then reduced by sodium carbonate (Na.sub.2CO.sub.3),
thereby resulting in formation of copper carbonate (CuCO.sub.3),
which is then converted by heating into copper oxide (CuO).
[0036] As shown in FIG. 4, a fourth method embodied in the present
invention is used to recycle copper contained in the PCB. The
method involves a first step in which the discarded printed circuit
boards are immersed in the sulphuric acid (H.sub.2SO.sub.4),
thereby resulting in formation of copper sulphate (CuSO.sub.4) as
shown in the following chemical reaction.
Cu+H.sub.2SO.sub.4.fwdarw.CuSO.sub.4+H.sub.2.uparw.
[0037] A reductant, sodium hydroxide (NaOH), is added to the copper
sulphate (CuSO.sub.4) solution to form copper hydroxide,
Cu(OH).sub.2, and sodium sulphate, Na.sub.2SO.sub.4, as shown in
the following chemical equation.
CuSO.sub.4+2NaOH.fwdarw.Cu(OH).sub.2.dwnarw.+Na.sub.2SO.sub.4
[0038] The copper hydroxide, Cu(OH).sub.2, is harvested and then
converted by heating into copper oxide (CuO) as shown in the
following chemical reaction. ##STR4##
[0039] The ionization of copper by sulphuric acid (H.sub.2SO.sub.4)
may be accelerated by use of hydrogen peroxide, aeration, or
electrode. The copper oxide so formed can be used directly as an
industrial raw material, while the sodium sulphate
(Na.sub.2SO.sub.4) is crystallized by heating prior to being useful
as industrial raw material.
[0040] It must be noted here that the hydrochloric acid may be
replaced by an electroplating waste fluid, etching waste fluid, or
copper chloride waste fluid, which is a waste product of the
manufacturing process of PCB. These waste fluids contain copper, as
well as ionizing acid capable of ionizing the copper. The copper
ions are then reduced by sodium hydroxide (NaOH), thereby resulting
in formation of copper carbonate (CuCO.sub.3), which is then
converted by heating into copper oxide (CuO).
[0041] Referring to FIG. 5, a fifth method embodied in the present
invention is designed to recycle copper from the discarded printed
circuit boards. The method involves an initial step in which the
discarded printed circuit boards are immersed in a solution of
oxalic acid (HOOCCOOH-1/2H.sub.2O). As a result, a powdered copper
oxalate (CuC.sub.2O.sub.4-1/2H.sub.2O) is formed, as shown in the
following chemical equation.
O.sub.2+2Cu+2(HOOCCOOH-2H.sub.2O).fwdarw.2(CuC.sub.2O.sub.4-1/2H.sub.2O).-
dwnarw.+5H.sub.2O
[0042] The precipitate of copper oxalate is converted by heating in
presence of oxygen into copper oxide (CuO), as shown in the
following chemical equating. ##STR5##
[0043] It must be noted here that the precipitate of copper oxalate
(CuC.sub.2O.sub.4-1/2H.sub.2O) is obtained by filtration. The
copper oxide so produced is directly used as an industrial raw
material.
[0044] As shown in FIG. 6, a device is designed for use in the
methods of the present invention as described above with reference
to FIGS. 1 through FIG. 5. The device comprises a reaction tank 10,
a precipitation bath 20, a conversion oven 30, and a heater 40. The
reaction tank 10 is provided in the wall with an acid exit 11. The
precipitation bath 20 is provided in the wall with an acid inlet
21, an outlet 22, and a discharge port 23 of sodium salt The acid
inlet 21 is connected with the acid exit 11 of the reaction tank 10
by a connection pipe 24 which is provided with a valve 241. The
precipitation bath 20 is provided with an electric agitator M. The
conversion oven 30 has a feeding port 31, a discharging port 32, a
feeding controller 33, a see-through window 34, an isolation tank
35, and a dust remover 36. The feeding port 31 is located at the
top of the conversion oven 30. The discharging port 32 is located
at the bottom of the conversion oven 30. The feeding controller 33
is disposed under the feeding port 31 for controlling the feeding
speed. The see-through window 34 is located in the wall of the
conversion oven 30 to facilitate the visual observation of the
process in progress. The isolation tank 35 is disposed on the
discharging port 32 for preventing copper oxide (CuO) from being
contaminated in the course of transfer of the copper oxide. The
dust remover 36 comprises a dust collecting tube 361, a water bath
362, and a venture tube dust cleaner 363. The dust collecting tube
361 is connected to the wall of the conversion oven 30. The venture
tube dust cleaner 363 is mounted on the tube wall of the dust
collecting tube 361. A water pipe 364 is connected with the venture
tube dust cleaner 363 and the water bath 362. The water pipe 364 is
provided with a pump 365. The venture tube dust cleaner 363 has a
suction force, by means of which the steam and the powered copper
oxide are drawn form the conversion oven 30 into the dust
collecting tube 361. Meanwhile, the water is pumped by the pump 365
into the venture tube dust cleaner 363 from the water bath 362, so
as to facilitate the collecting of the powered copper oxide and the
steam in the water bath 362 in which the copper oxide precipitates.
The heater 40 is disposed in the interior of the conversion oven 30
and is provided with a plurality of conveyers 41 which are used to
extend the reaction and to turn over the conversion product. Each
set of conveyers 41 is provided with a heating apparatus 42 by
which the temperature of the interior of the conversion oven 30 is
kept between 230 and 350. In addition, the conveyers 41 are
provided therebetween with a crushing wheel 43 and a dust shield 44
which is located over the crushing wheel 43 to avert dispersion of
dust.
[0045] Now referring to FIG. 1 and FIG. 6, the operation of the
device of the present invention calls for an introduction of an
appropriate amount of hydrochloric acid (HCl) into the reaction
tank 10. Subsequently, a predetermined number of the discarded
printed circuit boards are immersed in the reaction tank 10
containing the hydrochloric acid (HCl). As a result, the copper of
the discarded printed circuit boards is ionized to form a copper
chloride solution, which is transferred via the valve 241 to the
precipitation bath 20. As soon as the precipitation bath 20
contains an appropriate amount of the copper chloride solution, the
valve 241 is shut off. An appropriate amount of sodium carbonate
(Na.sub.2CO.sub.3) is added to the precipitation bath 20. The
mixture is stirred thoroughly by the electric agitator M. The
reaction products, sodium chloride (NaCl) and copper carbonate
(CuCO.sub.3), are formed, with the sodium chloride (NaCl) being
discharged via the discharging port 23 of the precipitation bath
20. The sodium chloride is crystallized by heating and is then used
as an industrial raw material. In the meantime, the copper
carbonate (CuCO.sub.3) is precipitated at the bottom of the
precipitation bath 20 and is discharged via the outlet 22 of the
precipitation bath 20 such that the copper carbonate is put through
a washing-dehydrating equipment "P", and that the copper carbonate
is fed into the conversion oven 30 via the feeding port 31 of the
conversion oven 30. The copper carbonate is heated in the interior
of the conversion oven 30 in such a manner that it moves from one
conveyer 41 to another. The copper carbonate (CuCO.sub.3) is thus
converted by heating into copper oxide (CuO), which is discharged
via the discharging port 32 and is used as an industrial raw
material.
[0046] As far as the embodiments described with reference to FIG. 2
through FIG. 5, the device is operated in similar manners described
above with reference to FIG. 1 and FIG. 6.
[0047] Referring to FIG. 7, a sixth method embodied in the present
invention is intended to recycle copper from the discarded printed
circuit boards. The method comprises a first step in which a
predetermined number of the discarded printed circuit boards are
immersed in a hydrochloric acid solution for ionizing the copper
contained in the discarded printed circuit boards, thereby
resulting in formation of a copper chloride (CuCl.sub.2) solution
as shown in the following chemical equation.
Cu+2HCl.fwdarw.CuCl.sub.2+H.sub.2.uparw.
[0048] The copper chloride (CuCl.sub.2) solution is mixed with an
aluminum material to form the copper powder and a poly aluminium
chloride, [Al.sub.2(OH).sub.nCl.sub.6-n.XH.sub.2O]m, aqueous
solution, as shown in the following chemical reaction.
m[(n+x)H.sub.2O+3[CuCl.sub.2]+2Al].fwdarw.3.sub.mC.sub.u+[Al.sub.2(OH).su-
b.nCl.sub.6-n''XH.sub.2O].sub.m+1/2.sub.nmH.sub.2
[0049] In the above chemical equation, n=1-5, m.ltoreq.10. The
aluminum material is dissolved in the copper chloride solution. The
aluminum material is recycled from the discarded material
containing aluminum, or from the aluminium chips, so as to reduce
the cost. In light of aluminium molecule being greater in activity
than copper molecule, the copper of the copper chloride
(CuCl.sub.2) is replaced by the aluminium, thereby resulting in
production of copper powder. The aqueous solution of the poly
aluminum chloride [Al.sub.2(OH).sub.nCl.sub.6-n.XH.sub.2O].sub.m is
used as a metal PAC in the water treatment.
[0050] As shown in FIG. 8, a seventh method embodied in the present
invention is used to recycle copper from the discarded printed
circuit boards. The method involves an initial step in which the
discarded printed circuit boards are immersed in a sulphuric acid
solution (H.sub.2SO.sub.4), thereby resulting in formation of a
copper sulphate (CuSO.sub.4) solution, as shown in the following
chemical equation.
Cu+H.sub.2SO.sub.4.fwdarw.CuSO.sub.4+H.sub.2.uparw.
[0051] The copper sulphate solution is then mixed with an aluminium
material to form copper powder and an aluminium sulphate aqueous
solution (Al.sub.2[SO.sub.4].sub.3), as shown in the following
chemical reaction.
3[CuSO.sub.4]+2Al.fwdarw.Al.sub.2[SO.sub.4].sub.3+3Cu
[0052] The aluminium material is obtained from the discarded
material containing aluminium, or from the aluminium chips, so as
to reduce the cost. In light of the aluminium molecule being
greater in activity than the copper molecule, the copper of the
copper sulphate (CuSO.sub.4) is replaced by the aluminium, thereby
resulting in production of copper powder. The
Al.sub.2[SO.sub.4].sub.3 aqueous solution is used as a metal PAC in
the water treatment.
[0053] Referring to FIG. 9, a device is used to carry out the
methods described above with reference to FIG. 7 and FIG. 8 The
device comprises a reactor 50, an acid reservoir 60, a PAC reaction
precipitation bath 70, a water tower 80, and a PAC washing and
storing apparatus 90. The reactor 50 and the acid reservoir 60 are
connected by a pipe 51 which is provided with a valve 52. The acid
reservoir 60 is provided in the wall with a solution transporting
pipe 61 which is in turn provided with a pump 62. The pipe 61 has
one end, which is extended into the PAC reaction precipitation bath
70. Located at the top of PAC reaction precipitation bath 70 is a
basket 71 for holding aluminium. Located at the bottom of the
precipitation bath 70 is a copper powder exit 72. The precipitation
bath 70 is further provided in the wall with a reaction circulation
pipe 73, which is provided with a reaction circulation pump 74 and
a reaction circulation valve 75. The reaction circulation pipe 73
has one end which is located at the top of the basket 71. A PAC
drain pipe 76 is disposed on the reaction circulation pipe 73
located between the reaction circulation pump 74 and the reaction
circulation valve 75. The PAC drain pipe 76 is provided with a PAC
output valve 77. The end of the drain pipe 76 is extended into the
PAC washing and storing apparatus 90. The water tower 80 is
provided in the wall with a water pipe 81 which is provided with a
reaction water admission valve 82 and has one end being extended
into the reaction precipitation bath 70. The PAC washing and
storing apparatus 90 has a washing and filtering tank 91 and a PAC
storage tank 92. The washing and filtering tank 91 is provided at
the top with a filter 93 and is provided in the wall with a PAC
output pipe 94 which is provided with a pump 95. The top of the
washing and filtering tank 91 is connected with a PAC filtration
pipe 96 a PAC storage pipe 97 and a return pipe 98. The PAC
filtration pipe 96, the PAC storage pipe 97, and the return pipe 98
are all connected with the PAC output pipe 94 and are provided with
a valve "V". The filter 93 and the water tower 80 are connected by
a washing pipe 931 which is provided with a valve 932.
[0054] Now referring to FIG. 7 through FIG. 9, the operation is
carried out by providing the reactor 50 with an appropriate amount
of hydrochloric acid (HCl) or sulphuric acid (H.sub.2SO.sub.4).
Thereafter, a predetermined number of the discarded printed circuit
boards are immersed in the reactor 50 for the purpose of effecting
the ionization of copper contained in the discarded printed circuit
boards, so as to form a solution containing copper. The valve 52 is
then opened to allow the copper-containing solution to flow into
the acid reservoir 60. As soon as the acid reservoir 60 contains an
appropriate amount of the copper-containing solution, the valve 52
is shut off. An appropriate amount of an aluminium material is held
in the basket 71. Meanwhile, the reaction water admission valve 82
is opened to allow a small amount of clean water to enter the
reaction precipitation bath 70. The pump 62 is then started to pump
the copper-containing solution into the PAC reaction precipitation
bath 70 from the acid reservoir 60. The reaction circulation pump
74 is simultaneously started while the reaction circulation valve
75 is opened. As a result, the aluminium material held in the
basket 71 is thoroughly bathed in the copper-containing solution
until such time when the PAC reaction precipitation bath 70 is
filled with the copper-containing solution. The copper of the
copper-containing solution is replaced by aluminium. The aluminium
product is precipitated at the bottom of the PAC reaction
precipitation bath 70 and is then discharged via the copper powder
exit 72. The PAC solution produced in the reaction is allowed to
enter the washing and filtering tank 91 via the PAC output valve 77
and the drain pipe 76. The valve "V" of the PAC filtration pipe 96
is opened to allow the passage of the PAC solution through the
filter 93. The valve "V" of the PAC storage pipe 97 is then opened
to allow the clean PAC solution to enter the PAC storage tank 92.
Upon completion of the filtration of the PAC solution, the valve
932 of the washing pipe 931 is opened to allow the water in the
water tower 80 to wash the filter 93 via the washing pipe 931. The
waste water contains PAC and is sent back to the PAC reaction
precipitation bath 70 via the return pipe 98.
[0055] The copper-recycling methods of the present invention
produce no by-product hazardous to environment. The present
invention described above is to be regarded in all respects as
being illustrative and nonrestrictive. Accordingly, the present
invention may be embodied in other specific forms without deviation
from the spirit thereof. The present invention is therefore to be
limited only by the scopes of the following claims.
* * * * *