Bx32469473

S.Pradeep Kumar, S.Govindaradjane, T.Sundararajan / International Journal of Engineering
Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 3, Issue 2, March -April 2013, pp.469-473
Recovery Of Copper From Printed Circiut Boards Through
Electrolytic Process –A Case Study
S.Pradeep Kumar1, S.Govindaradjane2, T.Sundararajan3
1
Assistant Professor, Department of Civil Engineering,
CK College of Engineering and Technology, Cuddalore-607003
2,3
Associate Professor and Professor, Department of Civil Engineering,
Pondicherry Engineering College, Puducherry-605014

ABSTRACT
Printed Circuit Boards (PCBs) collected
from local sources were used for recovering impact on human health and environment,
copper by electrolytic process, using a laboratory especially, in countries like: China, India, Pakistan,
reactor setup of working volume 15 liters and Ghana and Nigeria (Huo et.al, 2007; Kuper and
nitric acid for dissolution. Copper plate was used Hojsik, 2008 and Manhart, 2010).
as the cathode and graphite rod as the anode for PCB as a key component of WEEE, can be
the deposition process. Five durations were considered as a significant raw material due to its
adopted both for the dissolution and deposition complex composition, mainly consisting of metals
processes. Based on the above investigations it (40%), organics and ceramics (each 30%). Among
found that 5 hours for 132 gm copper has the various metals that are typically present in PCBs,
dissolved and the maximum copper deposited was copper is available in large quantity (27%), which
14.861 gm in 120 minutes, which is equal to 12% has considerable material value. Hence, efforts were
of maximum recovery of copper from the PCBs. directed to recover metals from PCBs, through best
The maximum power consumption is found to be available technologies, which helps not only manage
0.0214 kWh for 14.861 gm of copper recovered. hazardous substances scientifically, but also, to
The maximum copper (Cu) recovered in 120 reduce dependencies on primary metal resources.
minutes of the deposition process can be Two major techniques, namely,
considered as the optimum for the 5 L of Pyrometallurgical and Hydrometallurgical, were
dissolved solution. There is scope to refine the widely recognized for recovery of metal from e-
process and scale it up, if proper funding and waste (Cui and Zhang, 2008; Quinet et.al, 2005) and
facilities are made available. in the last decade the attention has moved to
hydrometallurgical process. Several investigators
Keywords – E-waste management, electrolytic cell have reported the feasibility of copper recovery by
process, operating conditions, recovery of copper, electrodeposition techniques (Oishi et.al, 2007;
recycling. Masavetas et.al, 2009). However, it has also been
reported that attention has been paid very rarely to
the relationship between the applied electrolytic
I. INTRODUCTION conditions and the recovered copper (Masavetas
Rapid technological progress made in
et.al, 2009). Hence, in this study recovery of copper
electronics, especially in the last decade, has led to
from PCBs, using the electrolytic process has been
very frequent replacement of electronic equipment.
investigated and an attempt has also been made to
Thus, used electrical and electronic equipment ended
study the performance of the copper recovery
up as waste materials. Waste Electrical and
process, based on the operational parameters such
Electronic Equipment (WEEE), popularly known as
as: electrolysis duration, energy consumption etc.
e-waste, is reported to be generated in the range of
20 to 50 million tones (MT), in the world (Heart,
2009). Printed Circuit Boards (PCBs) represent 3% II. MATERIALS AND METHODS
of mass of global WEEE generated (Dalrymple et.al, a) Printed Circuited Boards
2007). E-waste in general contains hazardous Based on the available literature, it was
substances, such as, toxic metals (Cadmium, found that there are no separate collection systems in
mercury etc.) and persistent organic pollutants (e.g.: India, and hence there is no authentic data available
halogenated flame retardants). Due to significant on the quantity generated and disposed-off every
risks to human health and environment posed E- year, and the resulting environmental risk. However,
waste, legislations have been enacted all over the a field survey conducted by the authors (Pradeep
world, for their collection, recycling and safe Kumar et al., 2013) on the IT industries located in
disposal. In spite of the existence of specific Puducherry (India), revealed that the general
legislation, recycling activities are mostly carried out awareness on the potential hazardous nature of e-
in poor working conditions, leading to adverse waste is rather poor, and that no attempt has been

469 | P a g e

made to recover metals, in spite of the fact that the anode and stainless steel mesh of diameter 100 mm
total e-waste generation is 11.06 TPA (at present). as the cathode for dissolution process. Copper plate
Hence, waste PCBs were collected from various of 40 mm width, 150 mm length and 10 mm thick
local sources and used as source material for the was used in the recovery process as cathode and the
present study. The waste PCBs were used in “as is same dimensional graphite rod was used as a anode
where is” basis, i.e. used in “as collected form”, in the recovery process. A direct current (DC) power
without giving any pretreatment. supply and a multimeter was used to measure the
current and voltage during the electrolytic process.
b) Electrolytic reactor setup The experimental setup adopted is shown in Fig. 1,
A glass reactor of working volume of 15L which is based on the one reported by Zeljko
was used for electrolytic process. The setup Kamberovic et.al, (2011).
consisted of a graphite rod of 25 mm diameter as the

Fig.1. Experimental setup of the electrolytic process
concentrated nitric acid (HNO3) was added first and
c) Methodology after that 300 gm sodium nitrate (NaNO3) was
The experimental methodology has been carried out added. (Nitric acid was added as it can dissolve
in three stages. The selection and preparation of metals like lead, tin and copper, but it does not
source material (PCBs) as a first stage, followed by dissolve gold). Nitric acid is steadily consumed
dissolution of metal present in PCBs into the during the dissolution and hence it has to be added
prepared solution as a second stage and finally periodically. Sodium nitrate was added in the bath as
recovery of the dissolved metals from the solution it helps to maintain the electrical conductivity of the
by electrolytic process, at the third stage. Capacitors, bath and hence the release of nitrate ions. Sulphuric
ICs, joints, mountings, etc. were removed from the acid could not be used as it does not dissolve copper,
PCBs and sorted manually. The PCBs were then cut but, it reacts with lead forming lead sulphate, which
into pieces as small as possible, and the cut pieces is water insoluble. The probable chemical reactions
were weighed. The weighed PCBs were then placed involved in the dissolution process are given in Eqn.
in the reactor. It was ensured that the cut pieces are (1).
in maximum contact with the graphite anode to
enhance the dissolution of the metal in the PCBs by HNO3 H+ + NO3-
+
improving the conductivity. The anode set was NaNO3 Na + NO3-
+
connected to the positive terminal of the rectifier and Na + H2O NaOH + H2 … (1)
stainless steel mesh was connected to the negative H2O H+ + OH-
terminal of the rectifier (current 1 A and voltage 0- H2O + 2OH- ½ O2 + H+
12V). Maximum possible current was set to carry Dissolution of metals present in PCBs takes place
out the experiment and the voltage was maintained according to the following reactions: [Eqn. 2(a) to 2
such that to achieve maximum current and hence (c)]
rate of dissolution. In the process, 5 liters of distilled For Copper:
water was taken in a container, then 500 ml Cu + NO3- Cu (NO3)2 + 2e- …2(a)

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For Lead: III. RESULTS AND DISCUSSION
Pb + NO3- Pb(NO3)2 + 2e- …2(b) a) Effect of electrolysis duration on dissolution
For Tin: and deposition process
Sn + 2NO3- Sn(NO3)2 + 2e- In the five sets of experiments that were conducted
-
Sn + 4NO3 Sn(NO3)4 + 4e- …2(c) for the dissolution and deposition processes the
Sn(NO3)4 + H2O Sn(OH)4 + HNO3 duration for the dissolution process was 5, 4, 3, 2, 1
Sn(OH)4 (Ignite) SnO2 (Fusion with alkali) Na2SnO3 hours and the initial amount of PCBs taken for the
dissolution process was 500 gm for every set of
The remains in the reactor were taken out, dried, experiment. Weight of the dried sample of PCBs
weighed, and the weight loss in the scrap was was noted after 5 hours of dissolution process and it
calculated, which is equal to the amount of metals was found that 132 gm was dissolved in nitric acid
that have gone into solution. The current, voltage bath. The results obtained during the dissolution and
and time were measured so as to calculate the energy deposition processes were presented in Figs 2 to 4.
consumed for the dissolution of metals. Based on the analysis of the results obtained, critical
The copper plate was polished by emery paper, inferences are drawn as detailed below:
cleaned with acetone and after drying the plate, its (i) Weight of PCBs dissolved goes on gently
initial weight was noted. This copper plate was increasing, with the rate of increase being
connected to negative terminal (cathode) and higher during initial stages, and stabilises at
graphite rod was connected to positive terminal latter stages, within the range of duration
(anode) of the rectifier. Both electrodes were dipped considered.
in solution and an external supply was given. The (ii) However, the weight of copper deposited in
copper ions in the solution move to the cathode for the cathode plate almost increases linearly
deposition. The probable reactions at anode and with time, barring the initial stage.
cathode are given in Eqn. 3(a) to 3(c) (iii) On the other hand, power consumption
Reaction at Anode: during the dissolution and recovery
H2O + 2OH- ½ O2 + H+ … (3a) processes with time, almost exhibit the
+
2H H2 … (3b) same trend.
Reaction at Cathode: Initial weight of the copper plate was noted for the
Cu2+ + 2e- Cu (deposited on cathode) … (3c) deposition process and after the electro deposition of
copper the deposited weight of copper in the cathode
A study was also conducted to analyze the governing electrode was assessed by taking the weight. The
parameters like: electrolysis duration both during for duration for the deposition process was set as: 120,
the dissolution and deposition processes. The study 90, 60, 30, 15 minutes. It was found that 14.861 gm
was also extended to understand effect of pH, energy of copper deposited during 120 minutes is the
consumption during both the dissolution and highest, among all the durations considered. It is
deposition processes, the relation between found that the maximum copper (Cu) recovered was
electrolysis duration with energy consumption for 12% and achieved after 120 minutes, in 5 L of
recovering the maximum percentage of copper. dissolved solution.

140
Wt. of PCBs (gm) dissolved

120
100
in solution

80
60
40
20
0
0 100 200 300 400
Time (min.)

Fig.2. Time (min.) Vs Weight of PCBs dissolved in
solution (gm)

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the reaction that is undergoing in the reactor. At the
16
end of the electrolytic process, pH was reduced to
Wt. of Cu deposited in cathode

14 near „neutral‟, by adding Na2 Co3 and NaOH (i.e.
12 12 gm / 100 ml and 7.2 gm /100 ml of acidic
10 solution), before it is disposed off, in an eco-
plate(gm)

8 friendly manner.
6 c) Energy consumption
4 Specific electrical energy consumption is
2 defined as the amount of electrical energy
0 consumed per unit mass of E-waste loaded and it
was calculated in terms of kilo watt hour (kWh)
0 50 100 150 one gram of copper recovered (kWh g-1 Cu). The
Time (min.) maximum power or energy consumption was found
to be 0.0214 kWh for 14.861gm of copper
recovered (Figs. 6&7). It can be seen that as the
Fig.3 Time (min.) Vs Weight of Copper deposited in cathode plate
power consumption increases drastically, as the
(gm)
weight of PBS dissolved in solution increases.
0.06 However, the weight of copper deposited increases
gently with increase in power.
0.05
140
Power (kWh)

0.04
Wt. of PCBs (gm) dissolved in 120
0.03
100
0.02
solution

80
0.01
0 60

0 100 200 300 400 40

Time (min.) 20
0
Fig.4 Time (min.) Vs Power consumption for
dissolution process (kWh) 0 0.02 0.04 0.06
0.025 Power (kWh)

0.02 Fig.6 Power (kWh) Vs Weight of PCBs dissolved
in solution (gm)
Power (kWh)

0.015
16
Wt. Cu deposited in cathode plate

0.01 14
12
0.005 10
8
0
(gm)

6
0 50 100 150
4
Time (min.) 2
0
Fig.5 Time (min.) Vs Power consumption for
recovery process (kWh) 0 0.005 0.01 0.015 0.02 0.025
b) Effect of pH
Power (kWh)
The pH of the solution i.e. in dissolution
process and deposition process was 1.0 (i.e. very
highly acidic), due to the usage of nitric acid for Fig. 7 Power (kWh) Vs Weight of Copper
dissolution of metals. No addition of any buffer deposited in cathode plate (gm)
solution was made for the study of pH variation in
the experimental investigations, as it would affect

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IV. CONCLUSION of Industerial Ecology, 15(1): 13-30,
i. For the recovery of copper from E-waste 2010.
(PCBs), the maximum duration for the 8) Masavetas I, Moutsatsou, Nikolaou,
dissolution process was found to be 5 Spanou S, Zoikis-Karathanasis A,
hours for the dissolution of 132 gm of Pavlatou E A, Spyrellis N, Production of
PCBs compounds and the maximum copper powder from PCBs by
duration of electrolysis for deposition of electrodeposition, Global NEST Journal,
copper was 120 minutes for 14.861 gm. 11(2): 241-247, 2009.
ii. The maximum power consumption was 9) Oishi T, Koyama K, Alan S, Tanaka M
0.0214 kWh for 14.861 gm of copper and Lee H, Recovery of high purity
recovered. copper cathode from PCBs using
iii. Maximum copper (Cu) recovered is 12% ammoniacal sulfate or chloride solution,
and it was achieved in 120 minutes using Hydrometallurgy, 89: 82-88, 2007.
5 L of dissolved solution. 10) Pradeep Kumar S, Govindaradjane S,
iv. The performance of the process seems to Sundararajan T, Management strategies
depend on the choice of the electrolyte, for various E-waste generators in
the initial state of PCBs, duration and Puducherrt region – A case study.
power consumed duration the dissolution International Journal of Emerging
and deposition stages. Technology and Advanced Engineering,
v. There is scope for improvement in the 3(1): 546-551, January 2013.
process and scaling it up, with the support 11) Quinet P, Proost J, Van Lierde A,
for research from funding agencies, as Recovery of precious metals from
laboratory investigation has its own electronic scrap by hydrometallurgical
limitations. processing routes, Miner. Metall. Process,
22(1): 17-22, 2205.
REFERENCES
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metals from electronic waste: A review,
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N, Geraghty K, Goosey M and Light foot
L, An integrated approach to electronic
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International Journal of Environmental
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4) Huo X, Peng L, Xu X, Zeng L Qiu B, Qi
Z, Zhang B, Han D and Piao Z, Elevated
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5) Kamberovic Z, Korac M, Ranitovic M,
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recovery of copper from printed circuit
boards (pcb), Association of Metallurgical
Engineers of Serbia, Metalurgija –
MJOM, 17(3): 139-149, 2011.
6) Kuper J and Hojsik M, Poisoning the
poor: Electronic waste in Ghana,
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