RECOVERY OF METALS FROM ELECTRONIC WASTE (e-scrap).

Haytham Al Fiqi Books: http://amzn.to/27nSCB9
RECOVERY OF
METALS FROM
ELECTRONIC
WASTE (e-scrap).
INTRODUCTION:
E-Waste i.e. electronic waste is discarded electronic equipments. In other words it
refers to the electronic products nearing the end of their useful life period. It includes a broad
range of electronic devices from computer to hand – held cellular phones, stereos, consumer
electronics, ovens, refrigerator, monitors, etc.
Waste of all sort put together is a major cause of Global Warming and electronic
waste (e-waste) is one of the biggest contributor. E-Waste contains several different
substances and chemicals, many of which are toxic & are not biodegradable and are likely to
create adverse impact on environment and health, if not handled properly. In addition to that
it contains metal values which can be recovered.
Manufacturers, government agencies and users are now looking for environmentally
responsible management of this E-waste. Besides proper disposal, economical recovery of
precious and exhaustible materials is also a matter of interest.
Page | 1

(Table I -Ref 2)
AIM OF THE PROJECT:
In all electronic equipment thermosetting materials like epoxy, backelite are present.
In today’s practice it is heated in open environment to get the metal, when it is heated at high
temperature it gives lot of fumes and it becomes charry. It causes environmental and health
problems. Our aim is to make the process eco-friendly, convenient and recover the metal
values almost quantitatively.
OBJECTIVE OF WORK:
If treated properly, electronic-waste is a valuable source for secondary raw material.
However, if not treated properly it is a major source of toxins.
Page | 2

In the present practice, uncontrolled burning, disassembly, and disposal are causing
environmental and health problems, including occupational safety and health effects among
those directly involved, due to the methods of processing the waste.
As the prices of gold, silver, copper, tin and lead continue to rise; recovery of these
metals from e-waste has become more desirable.
At present there are few processes to recover the metal values in an environmentally
safe manner. Hence, through our e-waste metal recovery process, we intend to recover the
metallic values in an environmentally safe manner.
LIST OF SUBSTANCES CONTAINED IN ENECTRONIC WASTE:
Page | 3

(Table II : Ref 2)
1) Substances in bulk: Epoxy resin, fiber glass, polychlorinated biphenyls,
polyvinyl chloride (PVC) and thermosetting plastics.
2) Elements in bulk: Lead, tin, copper, beryllium, iron and aluminium.
3) Elements in small amount: Cadmium, mercury.
4) Elements in trace amount: Gold, silver, antimony, arsenic, barium, bismuth, boron,
cobalt, gallium, palladium, manganese, platinum.
Although the amount of above elements mentioned are not always present in pcb, in
case of some PCB’s, there is gold and silver present in particular applications, in some
PCB’s they may not be present, but common elements like lead, tin and copper are
always present in pcb
LIST OF APPLICATION OF THE ABOVE ELEMENTS:
Almost all electronics contain lead and tin (as solder) and copper (as wire and PCB tracks).
1) Lead: solder, CRT monitors (lead in glass), lead-acid batteries.
2) Tin: coating on component leads.
3) Copper: copper wire, printed circuit board tracks, component leads.
4) Aluminium: nearly all electronic goods using more than few Watts of power (heat sinks),
electrolytic capacitors
5) Silicon: glass, transistors, ICs, printed circuit boards.
6) Gold: connector plating, primarily in computer equipment.
EXPERIMENTAL SETUP FOR RECOVERY
OF METALS FROM E-SCRAP
Page | 4

EXPERIMENTAL METHODOLOGY:
The experimental methodology is distributed in three main sections:
I) Selection and preparation of e-scrap.
II) Dissolution of the metals present in e-scrap into prepared solution.
III) Recovery of these dissolved metals from solution by different metallurgical routes.
I) Selection and preparation of e-scrap for dissolution:
The various type of e-scrap was sorted according to categories as mentioned in
table 1. Only printed circuit boards (PCB’s) were taken from the e-scrap for experimental
work. The capacitor, IC’s, joints, mountings, etc. on PCB’s were removed and sorted
mechanically. The PCB’s were cut into pieces as small as possible. These PCB’s cut
pieces were weighed.
II) Dissolution of the metals present in e-scrap into prepared solution:
A] Method 1: Dissolution using nitric acid solution
i) In actual process, 8 liter of distilled water was taken in container, then 400ml
concentrated nitric acid (HNO3) was added and after that 300 gm sodium nitrate
(NaNO3) was added. Two magnetic stirrers were used for homogeneous stirring of the
bath. (Nitric acid was added because it dissolves the metallic value like lead, tin and
copper but it does not dissolve gold. Nitric acid was consumed during the dissolution;
Page | 5

hence nitric acid was added periodically. Sodium nitrate was added in bath because it
maintains the electrical conductivity of bath and furnishes the nitrate ions. Sulphuric
acid could not be used because it does not dissolve copper, and lead forms as a lead
sulphate, which is water insoluble.)
HNO3 H+
+ NO3
-
…….. (1).
NaNO3 Na+
+ NO3
-
…….. (2).
Na+
+ H2O NaOH + H2 …….. (3).
H2O H+
+ OH-
…….. (4).
H2O + 2OH-
½ O2 + H+
…….. (5).
ii) The weighed PCB’s were placed in a cloth bag. Then graphite rod of 25mm
diameter anode (Ti plate can also be used as anode as it is non consumable) was
inserted into the bag and also care was taken that the cut pieces are in maximum
contact with the graphite anode to enhance the dissolution of the metallic values in
the PCB’s by improving the conductivity. This all set-up is called as anode set.
iii)The anode set was connected to positive terminal of the rectifier and stainless steel
mesh was connected to negative terminal of the rectifier (current 0-12A and
voltage 0-15V). Maximum possible current was set to carry out the experiment;
the voltage was maintained such that to achieve maximum current and hence rate
of dissolution was maximum.
iv)The bag was shaken periodically as the metals dissolves and contact may become
loose, due to this it was noted that there was rise in current as conductivity
increases. After some time the current rise was not noticeable. It means that metal
values are in the solution. Dissolution of metallic values takes place according to
following reactions:
For Copper:
Cu + NO3
-
Cu(NO3)2 (goes in solution) + 2e-
…….. (6).
For Lead:
Pb + NO3
-
Pb(NO3)2 (goes in solution) + 2e-
…….. (7)
For Tin:
Page | 6

Sn + 2NO3
-
Sn(NO3)2 + 2e-
…….. (8.a)
Sn + 4NO3
-
Sn(NO3)4 + 4e-
…….. (8.b)
Sn(NO3)4 + H2O Sn(OH)4 + HNO3 …….. (9)
Sn(OH)4
(Ignite)
SnO2
(Fusion with alkali)
Na2SnO3 (water soluble)
v) The remains in the bag were taken out dried and weighed and the weight loss in
the scrap was calculated it means that much amount of metals have gone into
solution.
vi)The current, voltage and time were measured so as to calculate the energy
consumed for dissolution.
OBSERVATIONS:-
Expt. No.1
Weight of PCB before Dissolution=500gm
TIME VOLTAGE
(Volts)
CURRENT
(amp)
HNO3 ADDED IN
(ml)
12.05 PM 14.92 8.01 25
12.20 PM 9.02 10.03 -
12.40 PM 7.67 9.92 -
12.55 PM 9.68 10 -
1.10 PM 7.73 10 50
1.25 PM 7.41 9.98 50
1.40 PM 7.02 9.97 50
1.50 PM 6.78 9.99 100
2.10 PM 6.51 9.99 100
2.30 PM 6.33 9.96 100
3.00 PM 6.07 9.96 100
3.45 PM 5.80 9.93 200
4.35 PM 5.38 9.92 200
5.00 PM 5.34 9.85 -
Page | 7

Weight of PCB after Dissolution =382gm
Expt. No.2
Weight of PCB before Dissolution=500gm
TIME VOLTAGE
(Volts)
CURRENT
(amp)
HNO3 ADDED IN
(ml)
11.30 PM 10.63 9.98 -
11.45 PM 9.54 9.90 100
12.10 PM 8.93 9.86 100
12.25 PM 8.97 9.86 50
12.45 PM 8.55 9.85 50
1.30 PM 7.92 9.83 100
1.45 PM 8.04 9.82 50
2.00 PM 7.90 9.82 50
2.15 PM 7.9 9.80 50
2.30 PM 7.83 9.80 50
2.45 PM 7.68 9.79 50
3.00 PM 7.79 9.80 50
3.15 PM 7.57 9.80 -
Expt. No.3
Weight of PCB before Dissolution = (600+500+400) gm = 1500gm
We went on changing the scrap in this trial because it was not possible to dissolve
all the metallic values in one single trial, due to this we were able to increase the
concentration of metallic values in the same bath prepared before.
3.a ) Scrap of wt. 600gm :-
TIME VOLTAGE
(Volts)
CURRENT
(amp)
HNO3 ADDED IN
(ml)
1.30 PM 7.30 11.50 -
2.15 PM 7.25 11.35 200
3.00 PM 7.23 11.34 200
3.20 PM 7.22 11.31 100
3.30 PM 7.01 11.21 -
3.35 PM 7 11.20 100
3.50 PM 6.87 11.16 -
3.55 PM 6.82 11.15 100
4.05 PM 6.08 11.16 -
Page | 8

4.40 PM 6.92 11.13 300
4.50 PM 6.64 11.14 100
PCB’s were removed dried and weighed
pH = 1
3.b) Scrap of wt. 500gm was added:-
TIME VOLTAGE
(Volts)
CURRENT
(amp)
HNO3 ADDED IN
(ml)
11.20 PM 7.13 11.62 -
1.20 PM 6.71 11.68 -
pH = 1
3.c ) Scrap of wt. 400gm was added:-
TIME VOLTAGE
(Volts)
CURRENT
(amp)
HNO3 ADDED IN
(ml)
2 PM 7.07 11.80 -
2.20 PM 6.95 11.53 -
2.40 PM 7.36 11.45 -
3.30 PM 7.13 11.03 -
4.00 PM 6.85 11.11 -
pH = 1
Total weight of PCB scrap after drying= 527+383+298=1208gm
Weight loss = 1500-1208=292gm
Page | 9

Figure 1: LINE DIAGRAM OF THE SETUP
B] Method 2: Dissolution using Aqua regia solution
The residue from bag is subjected to treatment with 50% aqua regia (1 HNO3: 3 HCl),
and see if any green coloration is obtained. That indicates presence of gold. The metallic
values which were not dissolved in above mentioned treatment also gets dissolved in aqua
regia. The reaction in aqua regia are:
For Silver:
Ag + HNO3 AgNO3 + H2 ………(10)
For Gold:
Page | 10

HCl + HNO3 NOCl ………(11)
Au + NOCl AuCl3 (water soluble) + NO2 ………(12)
III) Recovery of the dissolved metals from solution by different metallurgical routes:
i) Recovery of copper by electro deposition method:
Cu plate was polished by emery paper; cleaned with acetone. After drying this
plate, initial weight was noted. This copper plate was connected to negative terminal
(cathode) and graphite rod was connected to positive terminal (Anode) of the
rectifier. Both electrodes were dipped in solution and supply was given.
Reaction at Anode:
H2O + 2OH-
½ O2 + H+
2 H+
H2
Reaction at Cathode:
Cu2+
+ 2e-
Cu (deposited on cathode)
Solution was taken 400 ml from the dissolved bath.
Bath
no.
Voltage
(V)
Current
(A)
Current
density
(A/m2
)
Initial wt.
of Cu plate
(gm)
Wt. of Cu plate
after
deposition(gm)
Time
(min)
Wt.
deposited(gm)
1 2.19 0.98-1 272.22 21.2680 21.8097 60 0.1417
Page | 11

2.a 3.4 1 277.77 17.6829 19.0059 120 1.323
2.b 3.4 1 317.46 30.3631 31.3290 55 0.9659
2.c 3.4 1 320.51 38.5673 39.1709 160 0.6036
ii) Recovery of copper by cementation method:
Mild steel plate was polished by emery paper; pickling was done (HCl
100ml+Antimony Trichloride 5%). It removes rust from the plate, this plate is dipped in
solution and copper gets deposited on mild steel plate.
The first two trials of dissolution experiment have been failed while cementation
process as excess time was given for the deposition by cementation due to which the bath
was fully oxidized by iron oxide.
In next three trials of dissolution experiment we gave less time for deposition by
cementation process and got the results as follows:
Weight of M.S Plate = 34.446 gm
Time of dipping in solution = 1 minute
The copper deposited on M.S. plate was scrapped out and weighed.
Weight of copper obtained = 0.152 gm.
POWER CONSUMTION
For dissolution experiment:
Exp.
no.
Initial wt. of scrap
sample (gm)
Net
Voltage
(V)
Net
Current
(amp)
Time
(min)
Power = V*I*t
(KWH)
1 500 7.55 9.82 295 0.3645
2 500 8.404 9.84 225 0.3110
3.a 600 6.3155 11.24 200 0.2366
3.b 500 6.92 11.65 120 0.1612
3.c 400 7.072 11.38 120 0.1610
For electro deposition of Cu:
Bath
no.
Wt. deposited
(gm)
Voltage
(V)
Current
(amp)
Time
(min)
Power = V*I*t
(KWH)
1 0.1417 2.19 0.98 60 0.0021
2.a 1.323 3.4 1 120 0.0068
2.b 0.9659 3.4 1 55 0.0031
Page | 12

2.c 0.6036 3.4 1 160 0.0091
QUALITATIVE ANALYSIS:
Confirmatory test for Lead:
After electro deposition of Copper, electrolyzed solution was taken for confirmatory
test. In that solution potassium iodide (KI) powder was added, which showed yellow
precipitate. This shows that the lead is present in the solution.
Confirmation of Tin:
While dissolution of e-scrap, tin gets precipitated as metastannic acid, from which tin
can be recovered. (ref 1.). We have separated the precipitate from solution.
RESULT:
1) PCB’s are containing copper, lead and tin along with non metallic particle.
2) We have recovered Copper successfully.
3) Our process is eco-friendly, convenient and recovers the metal values almost
quantitatively.
CONCLUSION:
It is possible to recover the metal values from e-scrap by anodic dissolution using
nitric acid bath.
FUTURE WORK:
1) The recovery of lead is in progress.
2) The recovery of tin is in progress.
3) It has been reported that there is gold and palladium present in PCB. Our aim is to
recover gold and other precious metals as well, along with copper, lead and tin.
We are trying to get the average percentage of each metal.
4) Neutralization of bath for disposal and can be reused.
2HNO3+Na2CO3 2NaNO3 + CO2 + H2O
pH = 7.
Page | 13

REFERENCES:
1) Leaching and electrochemical recovery of copper, lead and tin from scrap printed circuit
boards. (Journal of chemical technology and Biotechnology); (Chem Technol Biotechnol
77:449-457/ 2002).
2) Metallurgical recycling of electronic scrap EPD Congress 2006 Edited by S.M. Howard,
R.L. Stephens, C.J. Newman, J.-Y.J. Hwang, A.M. Gokhale, T.T. Chen,
TMS (The Minerals, Metals & Materials Society), 2006
T.P. Battle, M.L. Free, B.R. Davis, C.L. Harris, H. Henein, P.N. Anyalebechi, A.C.
Powell, G.K. Krumdick, and C.K. Belt.
3) Printed Circuit Board Recycling:A State-of-the-Art Survey
Jianzhi Li, Puneet Shrivastava, Zong Gao, and Hong-Chao Zhang, (IEEE
TRANSACTIONS ON ELECTRONICS PACKAGING MANUFACTURING, VOL. 27,
NO. 1, JANUARY 2004).
4) Recycling Technology for Electronic Appliances
Jyh-Herng Chen
Department of Materials and Mineral Resources Engineering
National Taipei University of Technology
No. 1, Sec. 3, Zhongxiao E. Rd.
Taipei, Taiwan, ROC
5) http://en.wikipedia.org/wiki/Electronics_waste (pg. no. 1-8)
6) http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TGF-4RSRDNX-4
(Journal of Hazardous Materials, Volume 158, Issues 2-3, 2008, pg. no. 228-256).
Page | 14

Autism - The Complete Guide for Parents
https://www.amazon.com/dp/1547004673
#haythamalfiqi How to Make Money with Outsourced Articles and Article
Marketing ? http://amzn.to/1Uv1kJE
#haythamalfiqi How to Start a Day Care Center? http://amzn.to/1RtPc5n
#haythamalfiqi India Travel http://amzn.to/1RwKd6c
#haythamalfiqi Law of attraction: (A Simple Guide to attract Wealth,
Health,power,and Happiness) http://amzn.to/1UmirNh
#haythamalfiqi Nursing Careers: Do You Have What It Takes
http://amzn.to/1pDLChD
#haythamalfiqi Public Contract Law: The Law Student's Guide to Pursuing a
Career in Public Contract Law http://amzn.to/1So19Ms
#haythamalfiqi Public Speaking: Secrets for Success http://amzn.to/1ZFuF3g
#haythamalfiqi The Quality of Life: health related quality of life questionnaire
http://amzn.to/1MKj4IL
#haythamalfiqi Self Insight and Professional Growth http://amzn.to/1Pyee13
#haythamalfiqi Sex Life after 60: ( Common Issues to Consider if you want to
have a Great Sex Life after 60 ) http://amzn.to/1RwLcTO
#haythamalfiqi Swimming Pool Guide http://amzn.to/1UUA5GS
#haythamalfiqi The Weight Loss Solution :: 53 Lessons for loss Your Weight
Forever http://amzn.to/1RmkIWt
#haythamalfiqi WHAT DO YOU WANT? how to design a plan for your life: how
to design a plan for your life http://amzn.to/1ZFuG7i
#haythamalfiqi Wood Working Guilds http://amzn.to/1UQoXMj
#haythamalfiqi Yoga :: An Easy Yoga for Beginners Guide (Lose Weight, And
Heal Your Body) http://amzn.to/1pR1P3Q *
#haythamalfiqi Criminal Law: International Criminal Police Organization
http://amzn.to/25qILcO *
#haythamalfiqi American Idol Contestants http://amzn.to/1So25jJ
#haythamalfiqi Bitcoin : The Ultimate Guide for Beginners
http://amzn.to/1pDMaUU
#haythamalfiqi Building Self Esteem http://amzn.to/1SeuCFV *
#haythamalfiqi Catch A Cheating Lover http://amzn.to/1VOHNTI
#haythamalfiqi Contracts http://amzn.to/1XW5urA *
#haythamalfiqi Cosmetic Surgery: Signs You May Need a Cosmetic Surgery
Facelift http://amzn.to/1pDMovi
#haythamalfiqi Credit Card Debt: Everything You Need to Know to Avoid the
Mistakes http://amzn.to/25qJafs
#haythamalfiqi Dog Training: : Complete Guide to Training Your Dog or
Puppy http://amzn.to/1Rml9A2 *
#haythamalfiqi Dream Interpretation: This book explains in detail the
interpretation of dreams http://amzn.to/1RHyZPq *
#haythamalfiqi E-Bay http://amzn.to/21NdtIr
Page | 15

#haythamalfiqi Eat Healthier: Tips for healthy eating http://amzn.to/1Tce5Y6
#haythamalfiqi Facebook Marketing http://amzn.to/1MKktit
#haythamalfiqi Green Tea: Why You Must Drink It? http://amzn.to/1MtiioD
#haythamalfiqi Hawaii Vacation: A Travel Guide http://amzn.to/1oetslD
#haythamalfiqi Christian Organizations http://amzn.to/1YhysTt
#haythamalfiqi Anime and Sci-Fi Collecting http://amzn.to/1QWiNmv
#haythamalfiqi Anger Management: A Grandiosity Mind Trapped in Anger
http://amzn.to/1UMgOrK
#haythamalfiqi Cat Behavior Training http://amzn.to/1XgS0sE
#haythamalfiqi A Firefighters Character http://amzn.to/1ZwoWfm
#haythamalfiqi A Good Mailing List for a Bad One http://amzn.to/1SYpp9P
#haythamalfiqi Wellness And Fitness http://amzn.to/1XgRNWw
#haythamalfiqi A Look at the Steps of Making Wine
http://www.amazon.com/dp/1533165661
#haythamalfiqi Haytham Al Fiqi blog : http://www.authorhaf.org/
Haytham Al Fiqi Fan Page https://www.facebook.com/authorhaythamalfiqi/
#haythamalfiqi Italy Vacations: A Travel Guide http://amzn.to/1UrvMmD
#haythamalfiqi #kindleunlimited Benefits of Affiliate Marketing
http://amzn.to/1fDkw4y
#haythamalfiqi #kindleunlimited The Encyclopedia of Dentistry(Part2)
http://www.amazon.com/dp/B00FHOZE6E
#haythamalfiqi #kindleunlimited The Encyclopedia of Dentistry
http://www.amazon.com/dp/B00FHN5S0C
#haythamalfiqi #kindleunlimited most effective way to make money on
Craigslist http://amzn.to/1fz14WF
#haythamalfiqi #kindleunlimited 78 Ways to Make Money Working from
Home http://amzn.to/1iFpyhq
#haythamalfiqi #kindleunlimited making money online as an affiliate with
Click bank http://amzn.to/1fz1uwt
Page | 16

#haythamalfiqi #kindleunlimited How to Earn Money online using Twitter
$100-$500 per day http://amzn.to/1lFBNdu
#haythamalfiqi #kindleunlimited Make Money Online - Using Pinterest
http://amzn.to/1rV8ZPW
#haythamalfiqi #kindleunlimited Niche blogging is easier then you think - 6
figure blogging , http://amzn.to/1o8Efst
#haythamalfiqi #kindleunlimited Fiverr Secrets http://amzn.to/1fUFzdF
#haythamalfiqi #kindleunlimited Secret Ways To Make Money On YouTube
http://amzn.to/1pV2Aqt
Jamaica-Vacations https://www.amazon.co.uk/Jamaica-Vacations-Haytham-
Al-Fiqi/dp/1533516634/ref=as_sl_pc_qf_sp_asin_til?tag=authorhaf-
21&linkCode=w00&linkId=&creativeASIN=1533516634
Page | 17

RECOVERY OF METALS FROM ELECTRONIC WASTE (e-scrap).

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to RECOVERY OF METALS FROM ELECTRONIC WASTE (e-scrap).

Similar to RECOVERY OF METALS FROM ELECTRONIC WASTE (e-scrap). (20)

More from suzi smith

More from suzi smith (20)

Recently uploaded

Recently uploaded (20)

RECOVERY OF METALS FROM ELECTRONIC WASTE (e-scrap).