GREEN ELECTRONICS 2011
Overview
of hydrometallurgical process
for the recovery of copper
from waste printed circuit boards
Authors:
Željko Kamberović, TMF BUMarija Korać, IC-TMF BU
Srđan Vračar, IMP BUMilisav Ranitović, SET
November 8 - 10, 2011Novotel Bucharest
Bucharest, Romania
•Around 40 million tonnes of WEEE are generated each year → significant risks to human health and environment
•Directive 2002/96/EC-promotes the collection and recycling
•Printed circuit boards (PCBs) → Main component of WEEE
Introduction
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
� Around 300,000 tonnes of PCB scrap generated
in Europe
�Significant source of:Metals (Copper, Aluminum, Iron, Zinc, Nickel, Precious metals)
Plastic
Ceramics
Objectives
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
•Development of hydrometallurgical process for the recovery of copper from WPCBs
– Pretreatment
– PCBs leaching
– Metals recovery
– Zero-waste approach
•Major hydrometallurgical recycling steps– Acid leaching
– Solution purification
– Metals recovery
– Wastewater treatment
Sample preparation
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
•Performed at S.E.Trade, Belgrade– Milling in QZ-decomposer & magnetic separation-Fe 5%
– Manual removal of Al on sorting belt-Al 8%
– Shredding to granulation -2mm- dust 2%
– Sieving fractions -2mm, -1.00mm + 0.071mm
PCBs granulate
Chemical composition
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
•AAS, ICP-AES & XRFSample 1
(collected by S.E.Trade)Sample 2
(collected by Pupin Inst.)
fraction -6mm fraction-1+0.071mm
Metals %(w /w) Metals %(w /w)
Cu 27,99 Cu 25,24
Al 0.47 Al 0,69
Pb 2,17 Pb 2,22
Zn 2,01 Zn 2,05
Ni 1,23 Ni 0,93
Fe 1,18 Fe 0,98
Sn 3,26 Sn 3,17
Au, ppm 440 Au, ppm 890
Pt, ppm 57 Pt, ppm 17
Ag, ppm 1490 Ag, ppm 1907
Pd, ppm 50 Pd, ppm 47
Ceramics 20.41 Ceramics 22.14
Plastics 32.07 Plastics 32.41
Cu Ag Rh Pd Pt Au
Lom 1 96.254 3.746
Lom 2 95.072 4.928
Lom 3 73.121 6.45 2.521 17.943
Lom 3 30.749 14.762 8.806 2.353 43.33
Lom 4 95.03 4.97
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
Granulometric/chemical composition
• Size reduction process should include cutting instead of hammer shredding for obtaining suitable shape & granulation
0,00 %
5,00 %
1 0,00 %
1 5,00 %
2 0,00 %
2 5,00 %
3 0,00 %
3 5,00 %
4 0,00 %
5,000
2,500
2,000
1,800
1,250
1,000
0 ,800
0,630
0,500
0,400
0,315
0 ,250
0,100
0,090
0,080
0,071
-0,0
71
0,00
1,00
2,00
3,00
4,00
5,00
6,00
7,00
0,00
5,00
10,00
15,00
20,00
25,00
30,00
35,00
40,00
45,00
5,000
2,500
2,000
1 ,800
1, 250
1,000
0 ,800
0 ,630
0 ,500
0,400
0 ,315
0, 250
0,100
0,090
0 ,080
0 ,071
-0,07
1
Zn
Ni
Fe
Pb
Sn
Cu
%C
u
%Z
n, N
i, F
e, P
b, S
n
• Separation of fine (dusty) fractions makes trouble-freehydrometallurgical processing
• Content of Fe magnetic phase could be reduced before hydro treatment
Experimental set-up
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
• Leaching tests set up
1. Electro-resistant heater, 2. Reaction glass vessel, 3. Cooler with condenser, 4. Stirrer, 5.Oxygen tube, 6.Peroxide dozer, 7. Digital pH, Eh & temperature measurement device
Results and discussion
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
• Dependence of leaching degree on process parameters
Literature overview
Previous work:Leaching of refractory copper ores (complex, aggregate, gold)
Material motion in reactor, dynamic conditions
Constant parameters Varied parameters
Fraction -1.0mm + 0.071mm Solid-liquid ratio 25-150 g/L
Stirring rate 300 rpm Temperature 50-80°C
Oxygen flow 16 L/h Acid concentration 1.2-2M
H2O2 amount 0-200mL
Material dynamics
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
Floating particles
Sediment particles
-1mm
100 rpm
-1mm
200 rpm
-1mm
300 rpm
-1mm
600 rpm
Results and discussion
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
• Influence of solid-liquid ratio and temperature
0 50 100 150 200 250 3000
10
20
30
40
50
60
70
80
90
100
50 g/L 100 g/L 150 g/L
cop
per
leac
hin
g d
egre
e (
%)
time (min)
0 50 100 150 200 250 3000
10
20
30
40
50
60
70
80
90
100
copp
er le
achi
ng
degr
ee
(%)
time (min)
80 oC
70 oC
60 oC
50 oCDecrease of S/L ratio to 50 g/L
increases Cu leaching degree up to 100%
Increase of T to 80°C increases Cu leaching degree up to 100%
Results and discussion
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
• Influence of acid concentration and H2O2
0 50 100 150 200 250 3000
10
20
30
40
50
60
70
80
90
100
2,0 M 1,5 M 1,2 M
cop
per
leac
hin
g d
egre
e (
%)
time (min)
0 50 100 150 200 250 3000
10
20
30
40
50
60
70
80
90
100
0 ml 100 ml 150 ml 200 ml
copp
er le
achi
ng
degr
ee
(%)
time (min)
Increase of acid concentration to 2M increases Cu leaching
degree up to 100%
Increase of H2O2 continous addition to 200mL increases Cu
leaching degree up to 100%
Optical microscopy
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
1.8 mm 1.0 mm 0.1 mm
After
dissolution
As
received
Results and discussion
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
• According to achieved results WPCBs optimal leaching parameters for laboratory conditions and for larger scale experiments are determined
Parameter Laboratory scale Pilot plant
Temperature 75-80°C 70°C
Time >5h <10h
O2 16L/h 80 L/kg/h
H2O2 40mL/h 50 kg/t
Acid concentration 1.5-2M 1.5-2M
Solid-liquid ratio 50-100g/L 150-200g/L
Stirring rate >300rpm ~300rpm
Experimental set-up
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
• Electrowinning set up- Cu extraction from leaching solution
1. Electrowinning cell, HDPP, K (Cu) | A (Pb) 2. Water bath, T°C, thermostated3. Stirrer, rpm4. AC/DC convereter
4
3
1
2
Results and discussion
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
• Influence of temperature and cell voltage on copper deposition
Temperature
Time, min
Cu deposition degree, %
40°C 480 83.250°C 480 83.960°C 480 84.0
0 100 200 300 400 500
0
20
40
60
80
100
% Copper recovery
Time, min
1,4 V
2,0 V
2,2 V
2,5 V
3,0 V
Increase of temperature does not increase Cu deposition degree
Results and discussion
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
EW conditions– Temperature 40 °C– Stirring rate 100 rpm– Time 15 h– pH 0.20
0 2 4 6 8 10 12 14
0
20
40
60
80
100
cop
per
rec
ov
ery
, %
time, h
99.4% Cu recovery
Optimumum conditions– Voltage 2.1V
– Current density 120-200 A/m2
– Temperature 40°C
– Time 15h
– Stirring rate 100rpm
Deposit qualityCuCuCuCu 99,04SnSnSnSn 0,412PbPbPbPb 0,19ZnZnZnZn 0,189AgAgAgAg 0,084FeFeFeFe 0,088
Results and discussion
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
Selective removal of metals from electrowinning solution by cementation– removal of Fe and Ni using Zn powder
• Zn powder 50% excess
• Constant stirring
• Temperature 20-40°C
• Time 15-30 min
Optimum conditions for cementation
– Time 30 min
– Temperature 30°C
Composition of Fe-Ni cement
Ni 25-30%
Fe 65-70%
Zn 5-10%
Cu 1%
Results and discussion
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
• Thiourea leaching of leaching solid residue• thiourea concentration 20 g dm-3
• concentration of acid (H2SO4) 10 g dm-3
• concentration of oxidants Fe3+ 6 g dm-3
• Pulp density (S/L) 20 % of solid
• Time ≥ 200 min
0 20 40 60 80 100 120 140 160 1800
20
40
60
80
100
Lea
chin
g de
gree
, Au%
Time, min
30 oC
40 oC
50 oC
0 20 40 60 80 100 1200
20
40
60
80
100
Lea
chin
g d
egre
e, A
u%
Time, min
400 rpm 600 rpm 800 rpm 1000 rpm
Results and discussion
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
• According to achieved results optimum conditions of thiourea leaching are
Thiourea concentration 20 g/L
Concentration of acid (H2SO4)
10 g/L
Concentration of oxidants Fe3+
(from Fe2(SO4)3)
6 g/L
Pulp density (S/L) 20 %
Temperature 40°C
Stirring rate 600 rpm
Time ≥ 200 min0 50 100 150 200 250 300 350 400
0
20
40
60
80
100
Au Ag
Le
ach
ing
de
gre
e,
%
Time, min
Results and discussion
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
• Valorization of precious metals from TU leaching solution by cementation– Extraction of Au and Ag using Zn powder
• Temperature 25-30°C
• Time 15-30min
• Stirring rate 250rpm
• Zn powder 3-5g/L
Efficiency of cementation (Ag+Au)
– 99.9%
Quality of Ag-Au cement
– Ag 51%
– Au 26%
– Zn 21%
Results and discussion
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
• Solid residue after sulphuric acid and TU leaching
• ceramics and plastics 80%
• Pb-Sn in metallic form 10%
and as sulphate paste
• Al and minor metals 3%
• Wastewater treatment• Neutralization of solution after Fe-Ni cementation and TU
leaching
• Neutralization performed using Ca(OH)2
• pH 11.0
• efficiency about 100%
Process flowsheet
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
purified
water
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
Process Flowsheet
Conclusions
GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania
• Copper could be valorized from WPCBs with efficiency >99%
• Nickel is produced in FeNi cement mud form and could be put up for sale (Ni refinery, FeNi production)
• Gold and silver are obtained as Dore metal powder and could be put up sale to refinery or internally refined up to commercial purity Au and Ag metal powders
• Palladium in suggested process remains in PbSn slime
• Zinc in neutralization product has commercial value and could be used in Zn smelter
• Main solid residue after sulphuric acid and TU leaching is solid waste containing ceramics and plastics, Pb-Sn in metallic form and as sulphate paste, Al and minor metals. This waste would be probably characterized as a hazardous waste and landfilling is forbidden. Pb and Sn refineries should be consulted for further treatment
• Gold amount present in waste material represent the most important economical criteria for techno-economical feasibility of process
• Amount of 500ppm of Au represent limit techno-economical value. Best results are expected with material that exceed 600ppm of Au for 100kg/batch, and over 700ppm of Au for 50kg/batch