of hydrometallurgical process for the recovery of …...Results and discussion GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania •Dependence of leaching degree on process

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


•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


•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


•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


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


• 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


• 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


Floating particles

Sediment particles

-1mm

100 rpm

-1mm

200 rpm

-1mm

300 rpm

-1mm

600 rpm



• 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%



• 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


1.8 mm 1.0 mm 0.1 mm

After

dissolution

As

received



• 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


• 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



• 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



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



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%



• 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



• 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



• 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%



• 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


purified

water


Process Flowsheet

Conclusions


• 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

Documents

of hydrometallurgical process for the recovery of …...Results and discussion GREEN ELECTRONICS 2011, November 8-10, 2011 Bucharest, Romania •Dependence of leaching degree on process