A Novel Recovery Process of Metal Values From Spent

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A Novel Recovery Process of Metal Values from Spent

Lithium-ion Secondary Batteries

Yu-Chuan LinProf. Rong-Chi Wang

Prof. She-Huang Wu

Thesis for Master of Science

Department of Chemical Engineering

Tatung University

J uly 2008


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ACKNOWLEDGEMENTS

Firstly, I would sincerely appreciate my advisor, Dr. Rong-Chi Wang

and Dr. She-huang Wu, for his conscientious guidance, education, discussion

and encouragement throughout the course of this research during the study of

master.

Secondary, thanks are also due to the members of committee, Rong-Chi

Wang,She-Huang Wu and Fu-Chang Huang, for their review and comments

on this thesis. Finally, I would like to thank all my classmates and Zheng-Han

Chen Wu for their assistance to finish this research and thankful to my

parents for their support and concern.

Yu-Chuan Lin


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ABSTRACT

The simulated experiments with the separation and recovery of metal

values such as cobalt, manganese, nickel and lithium from spent lithium-ion

secondary batteries were studied. A leaching efficiency of more than 99% of

cobalt, manganese, nickel and lithium could be achieved with 4 M HCl

solution, 80 oC leaching temperature, 1 h leaching time and 1/50 g/ml

solid-to-liquid ratio. The manganese in the leaching liquor was reacted

selectively and nearly completely with KMnO4 reagent, then the manganese

was recovered as MnO2 and manganese hydroxide. The nickel in the leaching

liquor was adsorbed selectively and nearly completely with

dimethylglyoxime. An addition of 1M NaOH solution to reach pH=11

allowed the selective precipitation of cobalt hydroxides. The remaining

lithium in the aqueous solution was readily recovered as lithium carbonate

precipitate by the addition of a saturated sodium carbonate solution. The

recovery of cobalt and manganese hydroxides would be used to synthesize

LiCoO2 and LiMn2O4 as a cathode in a common lithium-ion battery

configuration. The performance of the electrochemical properties was also

tested.

Keywords: leaching, recovery, lithium-ion secondary batteries.


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LiCoO2LiMn2O4 LiCo1/3Ni1/3Mn1/3O2

4M

80oC 1 1/50 g/ml

99% KMnO4

dimethylglyoxime

1MpH 11

100oC

LiCoO2 LiMn2O4


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TABLE OF CONTENTS

PAGE

ACKNOWLEDGEMENT ............................................................................... i

ABSTRACT (ENGLISH)............................................................................... ii

ABSTRACT (CHINESE) .............................................................................. iii

TABLE OF CONTENTS............................................................................... iv

LIST OF TABLES .......................................................................................viii

LIST OF FIGURES ....................................................................................... ix

NOMENCLATURE..................................................................................... xiii

CHARPTER

1 INTRODUCTION............................................................................. 1

2 LITERATURE REVIEW.................................................................. 6

2.1 Introduction of Lithium Ion Secondary Battery .......................... 6

2.1.1 Concept of the Secondary Lithium Ion Battery ................ 6

2.1.2 Cathode Materials ............................................................. 8

2.1.2.1 LiCoO2 Cathode Material....................................... 8

2.1.2.2 LiMn2O4 Cathode Material..................................... 9

2.1.2.3 LiMnO2 Cathode Material.................................... 10

2.1.2.4 LiNiO2 Cathode Material ......................................11

2.2 Lithium Ion Secondary Battery of Recycling Processes ........... 11

2.2.1 Physical Processes........................................................... 14

2.2.1.1 Mechanical Separation Processes......................... 14


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2.2.1.2 Thermal Treatment ............................................... 17

2.2.1.3 Mechanochemical Process ................................... 18

2.2.1.4 Dissolution Process .............................................. 20

2.2.2 Chemical Processes......................................................... 21

2.2.2.1 Acid Leaching....................................................... 21

2.2.2.2 Bioleaching........................................................... 24

2.2.2.3 Solvent Extraction ................................................ 24

2.2.2.4 Chemical Precipitation ......................................... 27

2.2.2.5 Electrochemical Process....................................... 30

2.3 Effect of Reaction Operating Conditions................................... 32

2.3.1 Effect of Leaching Process.............................................. 32

2.3.1.1 Effect of Acid Concentration ............................... 34

2.3.1.2 Effect of Reaction Temperature ........................... 38

2.3.1.3 Effect of Reaction Time ....................................... 42

2.3.1.4 Effect of Solid-to-Liquid Ratio (S/L)................... 42

2.3.2 Effect of Recovery Materials Process............................. 47

2.3.2.1 Effect of Precipitate of Manganese ...................... 47

2.3.2.2 Effect of Precipitate of Nickel.............................. 48

2.3.2.3 Effect of Precipitate of Cobalt.............................. 51

2.3.2.4 Effect of Precipitate of Lithium ........................... 53

2.3.3 Effect of Preparation of the Cathode Electrode .............. 53

3 EXPERIMENTAL .......................................................................... 57

3.1 Materials..................................................................................... 57

3.2 Experimental Procedure............................................................. 62

3.2.1 Leaching Process............................................................. 62

3.2.1.1 Simulated Experiment of Leaching Process ........ 62


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3.2.2 Recovery Materials Process ............................................ 63

3.2.2.1 Leaching Process for the Mixture ........................ 65

3.2.2.2 Sedimentation Reaction........................................ 65

3.2.2.3 Precipitate of Manganese ..................................... 67

3.2.2.4 Precipitate of Nickel............................................. 67

3.2.2.5 Precipitate of Cobalt ............................................. 68

3.2.2.6 Precipitate of Lithium........................................... 69

3.2.3 Purity Analyses of Recovery Materials .......................... 69

3.2.4 Electrochemical Analyses ............................................... 69

3.2.4.1 Powder Prepared by Solid-State Reaction ........... 69

3.2.4.1.1 Preparation of LiCoO2 Powder .................... 69

3.2.4.1.2 Preparation of LiMn2O4 Powder .................. 70

3.2.4.2 Preparation of the Cathode Electrode................... 70

3.2.4.3 Assembly of the Coin-Type Cell .......................... 71

3.3 Experimental Apparatus............................................................. 72

3.3.1 Leaching Process Apparatus ........................................... 72

3.3.2 Recovery Materials Process Apparatus........................... 72

3.3.3 pH Value Analyses Apparatus ........................................ 72

3.3.4 Filtration Experiments Apparatus ................................... 75

3.4 Characteristic Analysis of Cathode Active Material.................. 75

3.4.1 X-Ray Diffraction Analysis............................................. 75

3.4.2 Composition Determination............................................ 75

3.4.2.1 Atomic Adsorption Spectroscopy Analysis ......... 75

3.4.2.2 Inductively Coupled Plasma Optical Emission

Spectrometer Analysis......................................... 77

3.4.3 Capacity Retention Studies ............................................. 78


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4 RESULTS AND DISCUSSION...................................................... 79

4.1 Leaching Process ....................................................................... 79

4.1.1 Simulated Experiment of Leaching Process ................... 79

4.1.1.1 Hydrochloric Acid Concentrations....................... 80

4.1.1.2 Leaching Temperature.......................................... 80

4.1.1.3 Leaching Time...................................................... 87

4.1.1.4 Solid-to-Liquid Ratio (S/L) .................................. 91

4.1.2 Leaching Process for the Mixture ................................... 95

4.2 Recovery Materials Process....................................................... 95

4.2.1 Sedimentation Reaction .................................................. 95

4.2.2 Precipitate of Manganese ................................................ 98

4.2.2.1 pH Value............................................................... 98

4.2.2.2 Molar Ratio of Mn++ to KMnO4 (MRMP), and

Temperature .......................................................100

4.2.3 Precipitate of Nickel (Castillo et al., 2002)................... 103

4.2.3.1 pH Value............................................................. 103

4.2.3.2 Molar Ratio of [Ni(NH3)6]2+ to Dimethylglyoxime

(MRDN) ............................................................. 105

4.2.3.3 Precipitate of Nickel........................................... 105

4.2.4 Precipitate of Cobalt (Contestabile et al., 2001)........... 107

4.2.5 Precipitate of Lithium (Zhang et al., 1998)................... 107

4.3 Purity of Recovery Materials Tests ......................................... 108

4.4 Electrochemical Properties .......................................................113

5 CONCLUSIONS .......................................................................... 119

REFERENCES ........................................................................................... 122

APPENDIX A ............................................................................................. 133


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LIST OF TABLES

TABLE PAGE

2.1 Effect of solid-to-liquid ratio (S:L) on leaching of cobalt and lithium

with various leachants (Zhang et al.,1998) ......................................... 23

2.2 Experimental conditions with standardized solutions (Castillo et al.,

2002).................................................................................................... 31

2.3 Recovery processes for lithium-ion secondary batteries by different

investigators......................................................................................... 33

2.4 Effect of pH on the Adsorption of Ni by DMG-Treated Foam (Lee and

Halmann, 1976)................................................................................... 50

2.5 Determination of Mole Ratio of Ni and dimethylglyoxime(DMG) in the

Treated Foam (Lee and Halmann, 1976) ............................................ 52

3.1 Experimental sources of chemical reagents......................................... 58

4.1 Leached percent of different metals in the mixtiue (LiCoO2:

LiMn2O4:LiCo1/3Ni1/3Mn1/3O2 =1:1:1 in weight ratio) with CHCl=4M,

T=80 oC, S/L=1/50 g/ml and t=1h.......................................................96

4.2 Solubility products of chemical compounds (James and Speight, 2005)

............................................................................................................. 97

4.3 Purity analysis of recovery material of lithium ................................. 109

4.4 Purity analysis of recovery material of manganese ........................... 110

4.5 Purity analysis of recovery material of cobalt................................... 111

4.6 Purity analysis of recovery material of nickel................................... 112


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LIST OF FIGURES

FIGURE PAGE

2.1 The illustration of the intercalation reaction: (a) no reaction, (b)

intercalation, (c) extraction reaction (Whittingham, 1982). ................. 7

2.2 Flow sheet of the hydrometallurgical recycling process of lithium ion

secondary rechargeable batteries (Xu et al., 2008). ............................ 12

2.3 Flow sheet of the metal recovery process (Shin et al., 2005).............. 16

2.4 Scheme of the hydrometallurgical route evaluated in this paper to treat

NiCd, NiMH and lithium-ion secondary rechargeable batteries

(Mantuano et al., 2006). ...................................................................... 26

2.5 pH dependence of extraction of cobalt and lithium with 0.29 M

D2EHPA and 0.30 M PC-88A in kerosene (feed solution: [Co] = 17.25,

[Li] = 1.73 (g /L ); pH = 0.6) (Zhang et al., 1998).............................. 28

2.6 Flow-sheet of the recycling process for spent lithium-ion batteries

(Contestabile et al., 2001). .................................................................. 29

2.7 Effect of HNO3 concentration on LiCoO2 leaching (20 g /L, 75oC, 400

rpm, 30 min, 0.8 vol.% H2O2) ( Lee and Rhee, 2002). ....................... 35

2.8 Lithium recovery (%) vs. dissolution time in nitric acid at various

concentrations (Castillo et al., 2002). ................................................. 36

2.9 Manganese recovery (%) vs. dissolution time in nitric acid at various

concentrations (Castillo et al., 2002). ................................................. 37

2.10 Effect of temperature on leaching of cobalt and lithium with 6%

sulfurous acid solution (t = 30 min, S:L = 1:100) (Zhang et al., 1998).

............................................................................................................. 39

2.11 Effect of H2SO4 concentration and reaction time on the dissolution of


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LiCoO2 at 50oC (Nan et al., 2005). .................................................... 40

2.12 Effect of H2SO4 concentration and reaction time on the dissolution of

LiCoO2 at 90oC (Nan et al., 2005). .................................................... 41

2.13 Effect of reaction time on the dissolution of Co, Ni, and Cu using 3

mol L1 H2SO4 and 3 wt.% H2O2 at 70 C and S/L=1:15 (Nan et al.,

2006).................................................................................................... 43

2.14 Effect of reaction time on leaching of cobalt and lithium with 1 M

hydroxylamine hydrochloride solution (T = 80 oC, S:L = 1 : 100)

(Zhang et al., 1998). ............................................................................ 44

2.15 Effect of pulp density on cobalt (a) and lithium (b) leaching (Shin et al.,

2005).................................................................................................... 46

2.16 XRD patterns for LiCoO2 powder prepared by amorphous citrate

precursor process (Lee and Rhee, 2002). ............................................ 55

3.1 XRD patterns of LiCoO2...................................................................... 59

3.2 XRD patterns of LiMn2O4 ................................................................... 60

3.3 XRD patterns of LiCo1/3Ni1/3Mn1/3O2 .................................................. 61

3.4 Simulated experiment of leaching process. (Cathode active material is

LiCoO2 (A), LiMn2O4 (B) and LiCo1/3Ni1/3Mn1/3O2 (C).) ................... 64

3.5 Experimental procedure of the leached and recovery process for the

mixture. (Cathode active material is LiCoO2 (A), LiMn2O4 (B) and

LiCo1/3Ni1/3Mn1/3O2 (C).) .................................................................... 66

3.6 The coin-type cell fabrication.............................................................. 73

3.7 Schematic diagram of leaching and recovery cathode active material

apparatus.............................................................................................. 74

3.8 Schematic diagram of filtration apparatus........................................... 76

4.1 Effect of hydrochloric acid concentration on leached percent of cathode


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active material, LiCoO2 (A) with t = 1h, S/L = 1/50 g/ml and T=80oC.

............................................................................................................. 81


active material, LiMn2O4 (B) with t = 1h, S/L = 1/50 g/ml and T=80oC.

............................................................................................................. 82


active material, LiCo1/3Ni1/3Mn1/3O2 (C) with t = 1h, S/L = 1/50 g/ml

and T=80 oC. ....................................................................................... 83

4.4 Effect of leaching temperature on leached percent of cathode active

material, LiCoO2 (A) with t = 1h, S/L = 1/50 g/ml and CHCl=4M...... 84


material, LiMn2O4 (B) with t = 1h, S/L = 1/50 g/ml and CHCl=4M.... 85


material, LiCo1/3Ni1/3Mn1/3O2 (C) with t = 1h, S/L = 1/50 g/ml and

CHCl=4M. ............................................................................................. 86

4.7 Effect of leaching time on leached percent of cathode active material,

LiCoO2 (A) with CHCl=4M, T=80oC and S/L = 1/50 g/ml................. 88


LiMn2O4 (B) with CHCl=4M, T=80oC and S/L = 1/50 g/ml............... 89


LiCo1/3Ni1/3Mn1/3O2 (C) with CHCl=4M, T=80oC and S/L = 1/50 g/ml.

............................................................................................................. 90

4.10 Effect of solid-to-liquid ratio (S/L) on leached percent of cathode

active material, LiCoO2 (A) with CHCl=4M, T=80oC and t=1h. ....... 92


active material, LiMn2O4 (B) with CHCl=4M, T=80oC and t=1h. ...... 93


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active material, LiCo1/3Ni1/3Mn1/3O2 (C) with CHCl=4M, T=80oC and

t=1h..................................................................................................... 94

4.13 Effect of pH value on recycle percent of leach liquor of cobalt,

manganese, nickel and lithium. .......................................................... 99

4.14 Effect of pH value on recycle percent of cobalt, manganese, nickel

and lithium (Mn++ : KMnO4= 2). ....................................................... 101

4.15 Effect of molar ratio of Mn++ to KMnO4 and temperature on recycle

percent of cobalt, manganese, nickel and lithium (pH=2). .............. 102

4.16 Effect of pH value on adsorb of cobalt, nickel and lithium (C4H8N2O2:

[Ni(NH3)6]2+=2.5). ............................................................................ 104

4.17 Effect of molar ratio of C4H8N2O2 to [Ni(NH3)6]2+ on adsorb of cobalt,

nickel and lithium (pH=9). ............................................................... 106

4.18 XRD pattern of the recovery synthesized LiCoO2 powder................114

4.19 XRD pattern of the recovery synthesized LiMn2O4 powder. ............115

4.20 Voltage vs. capacity profiles of 1st to 30th cycles at the C/10 rate for the

recovery synthesized LiCoO2phase. .................................................116

4.21 Capacity profiles vs. cycle number of 1st to 30th cycles at the C/10 ratefor the recovery synthesized LiCoO2phase.......................................117

5.1 Flowsheet of the hydrometallurgical process for the recovery of

lithium, cobalt, nickel and manganese from spent lithium-ion

secondary batteries (cathode active material: LiCoO2 (A), LiMn2O4 (B)

and LiCo1/3Ni1/3Mn1/3O2 (C)). ...........................................................121


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NOMENCLATURE

CHCl hydrochloric acid concentration (M)

LP leached percent

Ksp solubility products of chemical compound

MRMP molar ratio of Mn++ to KMnO4

MRDN molar ratio of C4H8N2O2 to [Ni(NH3)6]2+

pH pH value

RP recycle percent

32COLiS solubility of Li2CO3 in aqueous solution (g/100 g H2O)

S/L solid to liquid ratio (g/ml)

T leaching temperature (oC)

t leaching time (h)

(( )

)%,%100reactionbeforeionconcentratsolid

reactionafterionconcentratsolid-reactionbeforeionconcentratsolid =

(( )

)%,%100reactionbeforeionconcentratliquidreactionafterionconcentratliquid-reactionbeforeionconcentratliquid

=


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CHARPTER 1

INTRODUCTION

Lithium primary batteries have been introduced to the market for

about 25 years, while lithium-ion secondary batteries or storage batteries

have less than 10 years of commercial development (Castillo et al., 2002).

Extensive research is currently going on to improve the secondary lithium

battery technology. Significant improvements consist in new design of

electrolyte system (polymer electrolyte) and replacement of the lithium

metal cathode electrode by lithium-storing materials, typically graphite

carbon, while the positive electrode is a lithium-containing compound

like LiCoO2, LiMn2O4, LiNiO2 or related oxides. These new storage

batteries are usually referred to as lithium ion secondary batteries.

A lithium ion secondary battery comprises a cathode, an anode,

organic electrolyte, and a separator. The lamination of a cathode, an

anode, and a separator by a pressing makes those electric contacts. The

anode is a copper plate coated with a mixture of graphite carbon,

conductor, binder, and additives. Similarly, the cathode is an aluminum

plate coated with a mixture of active cathode material, electric conductor,

binder, and additives. Here, LiCoO2, LiMn2O4, LiNiO2 or related oxides


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are used as the cathode material for almost all commercialized lithium ion

secondary batteries due to its suitable performances such as high energy

density, ease of manufacture, etc.

Nowadays, lithium-ion secondary batteries are widely used as

electrochemical power sources in mobile telephones, personal computers,

video-cameras and other modern-life appliances due to lithium ion

secondary battery having many suitable performances such as (Yoshio et

al., 1996):

(a) High energy density (~ 120 Wh/kg).

(b) High battery voltage (the average voltage of the lithium-ion batteries

is 3.6 V, which is 3 times as large as that of the Ni-Cd battery or the

nickel-metal hydride (Ni-MH) battery).

(c) Long charging-discharging cycle (500-1000 cycles).

(d) Large temperature range (- 20 to + 60C).

The household battery industry in the USA is estimated to be a US$

2.5 billion industry with annual sales of nearly 3 billion batteries. These

batteries, also known as dry cells, are used in over 900 million battery

operated devices (Lupi and Pilone, 2001). In Europe, 5 billion units of

batteries were produced in year 2000 (Bernardes et al., 2004). Therefore,


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the usage of lithium-ion secondary batteries has rapidly increased

consumption and, consequently, increases the produced metal-containing

hazardous waste. The worldwide production of lithium-ion secondary

batteries is about 250 million tons every year. The annual production of

spent lithium-ion secondary batteries which contain 515 wt%-Co and

27 wt%-Li is estimated to be 200500 metric tons (Fouad et al., 2007).

The storage capacities of special waste dump sites are limited, and the

disposal costs are very high. Moreover, the French law regarding

collection and elimination or recycling of cells and storage batteries has

been reinforced since January 2001 and it must be applied to all the types

of batteries (Mortgat et al., 2000). So, recycling of the major components

of spent cells appears to be a beneficial way to prevent environmental

pollution and raw material consumption.

Up to now, some typical hydrometallurgical and pyrometallurgical

processes for the recycling of spent lithium-ion secondary batteries have

been reported or patented. In these reported hydrometallurgical process,

di-(2-ethylhexyl) phosphoric acid (D2EHPA), trioctylamine (TOA),

diethylhexyl phosphoric acid (DEHPA) or 2-ethylhexyl phosphonic acid

mono-2-ethylhexyl ester (PC-88A) were usually used as extracts to


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separate the metal values (Nan et al., 2006). In addition, using spent

lithium-ion secondary batteries to prepare LiCoO2, LiMn2O4, LiNiO2 or

related oxides electrode materials (Lee and Rhee, 2003; Contestabile et

al., 2001; Nan et al., 2004; Castillo et al., 2002), metal hydride electrodes

(Wang et al., 2002; Prickett et al., 2001) were also investigated. In

October 2003, AEA Technology (AEAT) launched a 2 million pounds

sterling research and development facility in Sutherland, North Scotland,

for lithium-ion secondary batteries recycling. AEAT has developed a

water based technique for the recycling of spent lithium-ion secondary

batteries. The process consists of three steps: mechanical grinding,

separation of electrolyte and electrode materials in aqueous solution, as

well as reduction of LiCoO2 by electrolysis. One advantage of aqueous

approaches is the low temperature ranges, which results in energy savings

(Lain, 2001).

In this study, the separation and recovery of metal values such as

cobalt, manganese, nickel and lithium from spent lithium-ion secondary

batteries were studied. Experiments have been carried out on dissolution

in acid solution, neutralization, precipitation, oxidation reduction and

filtering, various separation procedures using different oxidizing agents,


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etc. The leaching experimental parameters included leaching

concentration, temperature, time and solid-to-liquid ratio on leaching of

cobalt, manganese, nickel and lithium contained in the cathode material

of the batteries. The experimental parameters of separation included

oxidizing agent ratio and temperature, etc. The high effect and low cost

are the objectives in separation and recovery spent lithium-ion secondary

batteries.


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CHAPTER 2

LITERATURE REVIEW

2.1 Introduction of Lithium Ion Secondary Battery

2.1.1 Concept of the Secondary Lithium Ion Battery

Primary lithium ion batteries have been become commercial goods

since 1970, however, they are not rechargeable. In 1978, the intercalating

materials were introduced first by Murphy et al.. They found that Li-ions

could migrate into/out from LiWO4 structure via intercalation

/de-intercalation reactions. Intercalation and de-intercalation, the word in

materials science, are considered as a guest material enters and leaves a

host material without ruining the structure of host material as Li-ions

diffusing into and out from the structure. For example, it is just similar to

make water enter into and leave out a sponge by squeezing it, while the

main structure of the sponge is not destroyed. As shown in Figure 2.1

(Whittingham, 1982), Armand et al. (1980) defined intercalation as

LiyMnYm + AzBw Li(y-x)MnYm + LixAzBw.

Though, the idea of rocking chair for rechargeable batteries was

proposed in associated papers and patents published and agreed during

1980 ~ 1984(Padhi et al., 1997; Murphyetal et al., 1978; Belharouak et al.


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Figure 2.1.The illustration of the intercalation reaction: (a) no reaction,

(b) intercalation, (c) extraction reaction (Whittingham, 1982).


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, 2003). Until 1990, the first rechargeable lithium cell with components

of LixC6 / LiClO4 in PC/EC / Li(1+x)CoO2 or Li(1+x)YO2 (Y = Ni or Mn) to

adopt the principle was made. The secondary lithium cells, consisting of

LiCoO2 as a cathode (positive electrode) and carbon as an anode

(negative electrode), show good cycling performance and high energy

density. They have been used as the major power sources for portable

electric devices.

2.1.2 Cathode Materials

During the recent years, tremendous researches have been done to

find alternative cathode materials to replace LiCoO2 for its high cost and

limit availability. A lot of efforts have also been done to improve the

electrochemical characteristics of the cathode materials, such as LiCoO2

(Choi et al., 2004), LiMn2O4 (Venkatraman et al., 2004), LiNiO2 (Fan and

Jiang, 2004), LiNi1-x-yMxMyO2 (Kang and Amine, 2003), LiFePO4

(Takahashi et al., 2005).

2.1.2.1 LiCoO2 Cathode Material

Yoshio et al. (1996) indicated at present, LiCoO2 was the most

commonly used cathode material for commercial rechargeable lithium ion

batteries due to its advantage of easy preparation, high voltage (about


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3.9V), good reversibility (upon 500th), and high theoretical capacity

(about 280 mah/g). LiCoO2 is layered structure in witch the Li+ and Co3+

ions occupy alternating (1 1 1) layers of octahedral sites in a rock-salt

structure. The typical reversible limit of delithiation for LixCoO2 in

commercial batteries is x=0.5 at a voltage plateau of 3.8V (Choi and

Manthiram, 2004), which corresponds to a discharge capacity of about

140 mahg-1. However, layered LiCoO2 often suffers from structure

instability and safety programs. The charging reaction is (Zhang et al.,

1998):

LiCoO2 Li(1x)CoO2 + xLi+ +xe (2.1)

The delithiated phase of LiCoO2 contains Co(IV), a strong oxidant

which can give a highly exothermic reaction upon contact with the

electrolyte solvent. Caballero et al. (2004), Kobayashi et al. (2000) and

Ceder et al. (1998) used various strategies to avoid this drawback, like

replacing cobalt with another transition metal.

2.1.2.2 LiMn2O4Cathode Material

Wu et al. (2005) indicated that LiMn2O4 had the theoretical

capacity about 147 mah/g, and the practical specific capacity is about 120

mah/g. It means that almost about 80% of Li-ion can be d-intercalated


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from LiMn2O4. The LiMn2O4 material has many advantages including

low material costs, low toxicity, high cell voltage and synthesis easily.

However, it is suffered by two main issues, i.e., one is by the poor cycle

life induced by the John-Teller distortion as it is reduced into LiMn2O4,

and the other is the Mn2+ ion dissolution into the electrolyte after cycling.

2.1.2.3 LiMnO2 Cathode Material

LiMnO2 may exist in the same layered structure as LiCoO2 exists

in orthorhombic phase. The o-LiMnO2 has the high theoretical capacity of

285 mahg-1 based on the Mn3+/Mn4+ redox couple, and Mn is cheaper and

lower toxicity than Ni and Co. It can be synthesized by a conventional

solid state reaction methods, sol-gel, Pechini, ion-exchange, or

hydrothermal methods (Armstrong and Bruce, 1996; Tabuchi et al., 1998).

Vitins and West (1997) indicated that LiMnO2 was not

thermodynamically stable as a layered structure, but as an orthorhombic

phase of o-LiMnO2. However, both the layered and orthorhombic

LiMnO2 were observed to undergo a detrimental phase transformation

into a spinel-like phase through minor atomic rearrangements during the

first removal and subsequent cycling of Li, leading to eventual

degradation of electrode performance.


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2.1.2.4 LiNiO2 Cathode Material

Layered structure LiNiO2 cathode material was developed by Moli

Energy Co. in 1990 in Canada after Sony introduced the LiCoO2 cathode

material (Kubo et al., 1997). Song et al. (2004) indicated that LiNiO2 with

moderate cost and specific capacity of 190 mah/g was thought to be a

good candidate for the cathode material of lithium ion batteries, but

synthesized a pure compound was complex and difficult. The ideal

structure of LiNiO2 is layered, the same structure as LiCoO2, however,

the Li-Ni-O system is characterized by existence of a Li1-xNi1+xO2 (0


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lithium ion secondary battery should be experienced to some types of

physical processes as pre-treatment processes such as skinning, removing

of crust, crushing, sieving and separation of materials in order to separate

the cathode materials from other materials. Secondly, the separated

cathode materials will be used to recovered cobalt and other metals

through a series of chemical processes.

Safety precaution should be paid attention and be emphasized when

lithium ion secondary battery are manually dismantled (Tong et al., 2005;

Dorella and Mansur, 2007). First, the plastic cases of the batteries were

removed using a small knife and a screwdriver. Second, in order to

remove the metallic shell that covered the battery, it was immersed into

liquid nitrogen for 4 min and fixed in a lathe. Such a cryogenic method

was adopted for safety precautions. Third, the metallic shell was then cut

using a saw; the ends of the metallic shell were removed firstly and a

longitudinal cut was done aiming to access the internal material of the

battery which was removed using pliers. Fourth, anode and cathode were

uncurled manually, separated and dried for 24 h at 60 oC. All steps in the

experimental procedure were carried out using glasses, gloves and gas

masks for safe operation.


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2.2.1 Physical Processes

Tenorio et al. (1999) reported among physical processes for

recycling spent lithium ion secondary battery, mechanical separation

techniques intend to separate materials according to different properties

like density, conductivity, magnetic behavior, etc. Thermal processes are

usually associated with the production of steel, ferromanganese alloys or

other metallic alloys. Mechanochemical (MC) process is to use a grinding

technique that makes the crystal structure of the LiCoO2, the positive

electrode in the lithium ion secondary battery, into disordered system,

enabling useful substances such as Co and Li easily extracted by acid

leaching at room temperature from the lithium ion secondary battery

scraps wastes. Dissolution process is to use special organic reagents to

dissolve the adhesive substance (PVDF), which adheres the anode and

cathode electrodes, and therefore this process can make LiCoO2 get

separated from their support substrate easily and recovered effectively

(Contestabile et al., 2001).

2.2.1.1 Mechanical Separation Processes

Mechanical separation processes are usually applied as a

pretreatment to treat the outer cases and shells and to concentrate the


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metallic fraction, which will be conducted to a hydrometallurgical or a

pyrometallurgical recycling process in recycling of spent lithium ion

secondary battery.

Shin et al. (2005) presented a process for the recovery of metal

from spent lithium ion secondary battery for possible application to a

commercial scale plant, including mechanical separation of lithium cobalt

oxide particles and a hydrometallurgical procedure for lithium and cobalt

recovery. The experimental procedure is illustrated in Figure 2.3. A series

of mechanical processes involving crushing, sieving, magnetic separation,

fine crushing and classification were carried out to yield enriched

particles of lithium cobalt oxide in sequence. Two stages of crushing and

sieving resulted in satisfactory separation of the metal bearing particles

from the waste. A magnetic separator was used to remove pieces of steel

casing. In order to eliminate small pieces of aluminum foil attaching to

the particles of lithium cobalt oxide, a fine crushing was followed. The

reason why mechanical separation is emphasized before the metal

leaching process here is that it improves the recovery efficiency of target

metals and eliminates the need for a purification process of the leachate.

Because PVDF binder does not dissolve in acid solution, it remains in the


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Figure 2.3. Flow sheet of the metal recovery process (Shin et al., 2005).

Al


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cake after filtration. Also, carbon does not dissolve in acid solution, and

instead it floats on the solution; from filtration it is separated in the cake.

The electrolyte lithium exafluorophosphate (LiPF6) decomposes into

lithium fluoride and phosphor pentafluoride in the crushing process, and

the lithium dissolves in the acid solution during leaching. The organic

solvents, propylene carbonate (PC) and diethyl carbonate (DEC) were

evaporated in the crushing process.

2.2.1.2 Thermal Treatment

Lee and Rhee (2002) applied a recycling process involving

mechanical, thermal, hydrometallurgical and solgel steps to recover

cobalt and lithium from spent lithium ion secondary battery and to

synthesize LiCoO2 from leach liquor as cathode active materials.

Electrode materials containing lithium and cobalt can be concentrated

with a two-step thermal treatment. First, lithium ion secondary battery

samples were thermally treated in a muffle furnace at 100-150o

C for 1 h.

The samples were disassembled with a high-speed shredder. Second, a

two step thermal treatment was performed in a furnace, and electrode

materials were liberated from the current-collectors by a vibrating

screening. Next, the cathode active material, LiCoO2, was obtained by


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burning off carbon and binder in the temperature range 500-900 oC for

0.5-2 h. Third, after LiCoO2 in a nitric acid solution was leached in a

reactor, the gel was placed inside a stainless steel crucible and calcined

into powder in air for 2 h in the temperature range 5001000 oC.

Castillo et al. (2002) reported that the solid residue coming from

the operational step of the dilute HNO3 acid leaching of spent lithium ion

secondary battery and consisting of iron, cobalt and nickel hydroxides

mixture and some traces of Mn(OH)3, were introduced into a muffle

furnace at 500 oC during 2 h to eliminate carbon and organic compounds.

The alloy can then directly undergo beneficiation in metallurgical

applications.

2.2.1.3 Mechanochemical Process

Zhang et al. (2000) reported that room temperature extraction of

valuable substances from LiCo0.2Ni0.8O2 scrap containing the PVDF has

been carried out using 1N HNO3 solution after mechanochemical

treatment by a planetary mill with and without Al2O3 powder. Crystalline

LiCo0.2Ni0.8O2 in the scrap was pulverized and became amorphous by

mechanochemical treatment for 60 and 240 min, respectively, with and

without Al2O3 power. This shows that the addition of Al2O3 is very


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effective for mechanochemical treatment. Accordingly, Co as well as Ni

and Li were extracted at a high yield of more than 90% from the

amorphous scrap sample. About 1% of fluorine in PVDF was dissolved in

the filtrate when the Al2O3 powder was added to the scrap during the

mechanochemical treatment, while no fluorine was detected in the filtrate

obtained from the ground scrap sample without Al2O3 powder.

Saeki et al. (2004) developed an effective process for recovering

Co and Li from lithium ion secondary battery wastes by using

mechanochemical method. The process consists of co-grinding LiCoO2

with polyvinyl chloride (PVC) in planetary ball mill in air to form Li and

Co chlorides, and subsequent leaching with water of the ground product,

to extract Co and Li. In the grinding stage, mechanochemical reaction

between LiCoO2 and PVC takes place to form chlorides which are

soluble in water. Therefore, grinding stage is important to improve the

yield. PVC plays an important role as a chloride source for the

mechanochemical reaction. The grinding facilitates mechanochemical

reaction, and the extraction yields of both Co and Li are improved as the

grinding progresses. The 30 min grinding makes the recoveries of Co and

Li to reach over 90% and nearly 100%, respectively. Accordingly, about


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90% of chlorine in the PVC sample has been transformed into the

inorganic chlorides by the time. The concept of this process is to recycle

useful materials from the both wastes of battery and PVC.

2.2.1.4 Dissolution Process

Contestabile et al. (2001) presented a laboratory-scale spent lithium

ion secondary battery recycling process without the separation of anode

and cathode electrodes. The battery rolls were treated with

N-methylpyrrolidone (NMP) at 100 oC for 1 h and LiCoO2 was

effectively separated from their support substrate and recovered. The

recovery of both copper and aluminum in their metallic form was also

achieved. Although this process was very convenient, the recovery effects

of LiCoO2 were demonstrated to be influenced by the used adhesive

agent and rolling method of electrodes.

Xu et al. (2008) reported that this process has the advantage of

making LiCoO2 get separated from their support substrate and recovered

easily, and therefore this process greatly simplifies the separation

procedures of cobalt and aluminum. It still has the disadvantage that the

solvent for dissolving PVDF, N-methylpyrrolidone (NMP), is too

expensive and consequently is not very suitable for scale up operation.


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The further work to do in this respect is to develop much cheaper solvent

and make it recycled and reused in order that this treatment cost could be

decreased.

2.2.2 Chemical Processes

Chemical processes are connected to leaching steps in acid or

alkaline medium and purification processes in order to dissolve the

metallic fraction and to recover metal solutions that could be used by the

chemical industry. Recycling through chemical processes basically

consists of acid leaching or base leaching, chemical precipitation,

filtration, extraction or other processes.

2.2.2.1 Acid Leaching

The dust, which has been separated from plastic, iron scraps and

paper residues in the sorting and dismantling preliminary treatment step,

is leached by an acidic solution in order to transfer the metals of interest

from it to the aqueous liquor.

The leaching of LiCoO2 from spent lithium ion secondary battery is

usually carried out by using inorganic acids such as H2SO4 (Mantuano et

al., 2006), HCl (Contestabile et al., 2001) and HNO3 (Castillo et al.,2002;

Lee and Rhee, 2002) as leaching agents.


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Zhang et al. (1998) studied the leaching of LiCoO2 by the use of

H2SO3, NH4OHHCl and HCl as leaching agents. The experimental

results were show in Table 2.1. The experimental results indicated that

the leaching efficiency of Co is highest in hydrochloric acid among these

three leaching agents and higher the temperature, higher the leaching

efficiency of Co.

Mantuano et al. (2006) and Lee and Rhee (2002) studied the

leaching of LiCoO2 by the use of H2SO4 and HNO3 to substitute HCl with

the addition of hydrogen peroxide as a reducing agent respectively.

Lee and Rhee (2002) indicated that in the process of reductive

leaching with the addition of hydrogen peroxide as a reducing agent, the

leaching efficiency increased by 45% for Co and 10% for Li compared

with that in only nitric acid leaching. This behavior seems to be due to the

reduction of Co3+ to Co2+, which is readily dissolved. The leaching

efficiency of Co and Li increased with increasing HNO3 concentration,

temperature, and hydrogen peroxide concentration and with decreasing

S/L ratio. An effective condition for the leaching would be 1M HNO3,

10-20 g/L initial S/L ratio, 75oC, and 1.7 vol.% H2O2 addition.


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Table 2.1. Effect of solid-to-liquid ratio (S:L) on leaching of cobalt and

lithium with various leachants (Zhang et al.,1998)


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2.2.2.2 Bioleaching

It has been reported that bio-hydrometallurgical processes have

been gradually replacing the hydrometallurgical one due to their higher

efficiency, lower costs and few industrial requirements (Cerruti et

al.,1998). Bio-hydrometallurgical processing of solid waste is similar to

natural biogeochemical metal cycles and reduces the demand of resources,

such as ores, energy and landfill space (Moore et al., 2002).

The study of Mishra et al. (2008) was carried out on bioleaching

method for the extraction of cobalt and lithium from spent lithium ion

secondary batteries containing LiCoO2, using chemolithotrophic and

acidophilic bacteria, acidithiobacillus ferrooxidans, which utilized

elemental sulfur and ferrous ion as the energy source to produce

metabolites like sulfuric acids and ferric ion in the leaching medium.

The current technologies of bio-hydrometallurgical processes have

not gotten mature in their applications for recycling lithium-ion

secondary batteries and are still in the research stage until now (Xu et al.,

2008).

2.2.2.3 Solvent Extraction

Such extractants as di-(2-ethylhexyl) phosphoric acid (D2EHPA),


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Figure 2.4. Scheme of the hydrometallurgical route evaluated in this

paper to treat NiCd, NiMH and lithium-ion secondary rechargeable

batteries (Mantuano et al., 2006).


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from the hydrochloric acid leach liquor was performed employing solvent

extraction. Figure 2.5 gives the pH dependence of the extraction of cobalt

and lithium from the leach solution containing 17.25 g/L Co and 1.73 g/L

Li with 0.29 M di-(2-ethylhexyl) phosphoric acid (D2EHPA) and 0.30 M

2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) in

kerosene. It is found that the extraction of cobalt increases rapidly with

the increase of pH in the region of pH < 5 and essentially complete

extraction occurs when the pH is higher than 6.5. On the other hand,

lithium is not extracted at all at pH < 5.5 in all cases. Above pH 5.5,

lithium begins to extract slightly into the organic phase. It appears that

the extraction ability of D2EHPA for lithium is greater than that of

PC-88A.

2.2.2.4 Chemical Precipitation

Contestabile et al. (2001) studied a laboratory process aiming to the

treatment and recycling of spent lithium ion secondary batteries and being

composed of sorting, crushing and riddling, selective separation of the

active materials, lithium cobalt dissolution and cobalt hydroxide

precipitation. The flow sheet of the recycling process is shown in Figure

2.6. The cobalt dissolved in the hydrochloric solution was recovered as


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Figure 2.5. pH dependence of extraction of cobalt and lithium with

0.29 M D2EHPA and 0.30 M PC-88A in kerosene (feed solution: [Co]

= 17.25, [Li] = 1.73 (g /L ); pH = 0.6) (Zhang et al., 1998).


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cobalt hydroxide Co(OH)2 by addition of one equivalent volume of a 4M

NaOH solution. The precipitation of cobalt hydroxide begins at a pH

value of 6 and can be considered to be completed at pH 8.

Castillo et al. (2002) studied lithium and manganese are then

separated adding sodium hydroxide solution. The operating conditions

and separation results are reported in Table 2.2. The selective

precipitation separation process was applied on spent Li ion batteries,

after preliminary dissolution in acidic medium. The choice of the acid is

reported hereafter.

2.2.2.5 Electrochemical Process

Myoung et al. (2002) reported that cobalt ions, extracted from

waste LiCoO2 by using a nitric acid leaching solution, are

potentiostatically transformed into cobalt hydroxide on a titanium

electrode and cobalt oxide is then obtained via a dehydration procedure.

In linear sweep voltammetry, distinct cathodic current peak is observed

and indicates that hydroxide ions are formed near the electrode via the

electroreduction of dissolved oxygen and nitrate ions give rise to an

increase in the local surface pH of the titanium. Under appropriate pH

conditions, island-shaped cobalt hydroxide is precipitated on the titanium


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substrate and heat treatment of the cobalt hydroxide results in the

formation of cobalt oxide. The detailed reaction mechanisms are

considered to be:

2H2O + O2 + 4e= 4OH (2.2)

NO3 + H2O + 2e

= NO2 + 2OH (2.3)

Co3+ + e = Co2+ (2.4)

Co2+ + 2OH/ Ti = Co(OH)2 / Ti (2.5)

The reduction of dissolved O2 and nitrate ion, i.e., reactions (2.2)

and (2.3), could increase the local pH of the electrode. Thus, the

precipitation of hydroxide films of Co(OH)2 (see Eq. (2.5)) under

appropriate pH condition could be possible. Therefore, this process

provides a good way for recovering cobalt oxide from LiCoO2.

Finally, the differences of the lithium-ion secondary batteries of

recycling processes depicted from different precursors have been studied

as shown in Table 2.3.

2.3 Effect of Reaction Operating Conditions

2.3.1 Effect of Leaching Process

Some reaction conditions such as acid concentration of leaching

agent, leaching reaction temperature (T), leaching reaction time (t) and


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Table2.3.

Recove

ryprocessesforlithium-io

nsecondarybatteriesbydifferentinvestigators.

(thisstudy)


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Figure 2.7. Effect of HNO3 concentration on LiCoO2 leaching (20 g /L,

75 oC, 400 rpm, 30 min, 0.8 vol.% H2O2) ( Lee and Rhee, 2002).


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Figure 2.9. Manganese recovery (%) vs. dissolution time in nitric acid at

various concentrations (Castillo et al., 2002).


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Figure 2.10. Effect of temperature on leaching of cobalt and lithium with

6% sulfurous acid solution (t = 30 min, S:L = 1:100) (Zhang et al., 1998).


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Figure 2.11. Effect of H2SO4 concentration and reaction time on the

dissolution of LiCoO2 at 50oC (Nan et al., 2005).


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leaching efficiency of cobalt was favorable.

2.3.1.3 Effect of Reaction Time

The effect of reaction time on the dissolution of Co, Ni, and Co is

presented in Figure 2.13 (Nan et al., 2006). It is seen that the dissolution

of powder residues is enhanced with the increase of dissolving time, and

about 90% Co, Ni, and Co could be leached out after 5 h. In addition, it

was also found that the dissolution of mixed RE was over 99.5% in 5 h

under such dissolution conditions. The insoluble material could be put in

the posterior batch. So, the dissolving time of 5 h was chosen in the given

process.

Figure 2.14 gives the time dependency of the leaching of cobalt and

lithium with hydroxylamine hydrochloride solution (NH2OHHC1)

(Zhang et al., 1998). It is apparent that increasing the reaction time is

beneficial to metal leaching. About 92% of cobalt and lithium can be

leached within 30 min in the case of hydroxylamine hydrochloride

solution (NH2OHHC1).

2.3.1.4 Effect of Solid-to-Liquid Ratio (S/L)

Shin et al. (2005) reported in these experiments with the

concentration of sulfuric acid to be 2 M, and pulp density to be 50 g/L.


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High pulp density is desirable to raise processing throughput. Yet a

density higher than 50 g/L yields lower leaching efficiency, as illustrated

in Figure 2.15(a) for cobalt leaching and Figure 2.15(b) for lithium. The

leaching temperature was 75 oC with an agitation of 300 rpm. The

leaching rate was fast in the initial stage regardless of the hydrogen

peroxide concentration, whereas leaching efficiency depends upon the

amount of hydrogen peroxide. A concentration of 15 vol.% was enough

for the full leaching of both metal components. Because polyvinylidene

fluoride (PVDF) binder does not dissolve in acid solution, it remains in

the cake after filtration. Also, carbon does not dissolve in acid solution,

and instead it floats on the solution; from filtration it is separated in the

cake. The electrolyte lithium hexafluorophosphate (LiPF6) decomposes

into lithium fluoride and phosphor pentafluoride in the crushing process,

and the lithium dissolves in the acid solution during leaching. The organic

solvents of propylene carbonate (PC) and diethyl carbonate (DEC) were

evaporated in the crushing process. The concentrations of copper and

aluminum in the leachate were 0.46 g/L and 0.79 g/L, respectively, and

the amounts in the cake were less than 0.01 g.


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molecular mixing of the oxide species. Namely, the KMnO4 precursor

(~10 g/L) was titrated with a solution of Ce3+ and Mn2+ ions at constant

pH (8.0 0.3), to derive the following reactions:

MnO-4 + 3e- + 2H2O MnO2 () + 4HO- (2.6)

Mn2+ + 4HO- MnO2 () + 2e- + H2O (2.7)

Ce3+ + 4HO- CeO2 () + e- + 2H2O (2.8)

Considering the concentration of the MnO-4, Mn2+, Ce3+, Ce4+, and

OH- species and above Ksp values for a catalyst with a nominal Mnat/Ceat

ratio of 1, the redox potentials of the above reactions (+0.57 V (2.6);

-0.39 V (2.7); and -0.255 V (2.8)) confirm that the oxidation of the Ce3+

and Mn2+ cations by MnO-4 precursor should proceed owing to a

cell-concentration effect. This approach matches the core issue of

design, as the formation of the precipitated species occurs only further to

direct and selective molecular interactions between the oxidant and

the reducing species.

2.3.2.2 Effect of Precipitate of Nickel

Castillo et al. (2002) reported in the standardized solution (2) of

nickel (see Table 2.2), the solution was firstly treated with


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dimethylglyoxime to form a red solid complex with the nickel. The

complexation reaction is very selective and quantitative. Lithium and

manganese are then separated adding sodium hydroxide solution. The

operating conditions and separation results are reported in Table 2.2.

Lee and Halmann (1976) determined the optimum pH range, the

amount of Ni absorbed on the treated foam by the batch method at

various pH value in Table 2.4. Ni was found to be optimally adsorbed

from aqueous solution in the pH range of 8-10. These measurements were

carried out in solutions containing an excess of Ni, relative to the amount

of dimethylglyoxime (DMG) on the treated foam, so as to observe the

differences in the amount of Ni adsorbed. On the other hand, quantitative

adsorptions were possible even in solutions having both slightly lower

and higher than the above optimum pH values, if dimethylglyoxime

(DMG)-treated foam containing an excess of dimethylglyoxime (DMG)

were applied. However, in strongly alkaline solutions, above pH 11, the

amount of adsorbed Ni decreased, which may be due to an unfavorable

reaction condition for formation of the Ni- dimethylglyoxime complex, or

to low immobilizability of dimethylglyoxime on the treated foam in

strongly alkaline medium.


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recovered from spent lithium ion secondary battery as precursors to

produce LiCoO2 electrode material of lithium-ion batteries. The cobalt

oxalate was baked, and a molar ratio of cobalt : lithium = 1:1 was ground

until they were mixed equally. The mixed samples were heated firstly at

600 oC for 6 h, and then they were ground again and pressed into tablets.

LiCoO2 active material was synthesized after the tablets were heated at

800 oC for 10 h in the tube type stove. Then, LiCoO2 material, graphite,

ethyne and PVDF were mixed in a proportion of 86:6:2:6. The mixture

with N-methylpyrrolidone as solvent was pasted on aluminum foil to

prepare the test electrode; pure lithium piece was used as auxiliary

electrode.


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Figure 3.1. XRD patterns of LiCoO2.

10 20 30 40 50 60 70 80

0

2000

4000

6000

8000

10000

10 20 30 40 50 60 70 80

Intensity

2

LiCoO2

LiCoO2


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Figure 3.2. XRD patterns of LiMn2O4.

10 20 30 40 50 60 70 80

0

100

200

300

400

500

600

700

10 20 30 40 50 60 70 80

Intensity

2

LiMn2O

4

LiMn2O

4


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The leach liquor after the recovery of manganese in addition of 28

% NH3 solution until pH=3 to 13, changing molar ratio of C4H8N2O2 to

[Ni(NH3)6]2+: 1, 1.5, 2, 2.5, 3, as well as reaction time to be 10 min, in a

three neck glass extractor with agitation at a speed of 300 rpm were

investigated. After reaction, it was filtered and separated into leach liquor

and precipitate. The amounts of lithium, cobalt and nickel in the leach

liquor were measured to compute recovery efficiency of nickel.

Recovery of nickel from the precipitate (red solid complex) was

performed by employing hydroxide precipitation. It was filtered and

separated into dimethylglyoxime (C4H8N2O2) and nickel ion solution.

Dimethylglyoxime (C4H8N2O2) was recovered by dissolving the red solid

complex in the 50 ml, 4M hydrochloric acid solution. It will repeatedly be

used after separation. Nickel was recovered by addition of 1M sodium

hydroxide solution onto the nickel ion solution until pH=11, then filtered

and separated into leach liquor and precipitate.

3.2.2.5 Precipitate of Cobalt

Recovery of cobalt from the leach liquor ([Co(NH3)6]3+) after the

separation of nickel was performed by employing hydroxide precipitation,

i.e., addition of a hydrochloric acid solution until pH=0. Cobalt was


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dissolved in adequate amount of N-methylpyrollidone (NMP, ultra, ISP

Technologies Inc., U.S.A.). The prepared powder and acetylene black

were added to the above solution with weight ratio to PVDF of 80:10:10,

stirred for 24 h to sufficiently mix. The slurry prepared in the previous

step was smeared on the aluminum foil (thickness of 25 m) by tape

casting. The green tape was dried in vacuum oven of 80 oC for 24 hrs to

remove the residual solvent. The dried tape was punched into round plate

with diameter of 10 mm as the cathode electrode. The electrode plate was

pressed under pressure of 200 psi for 1 min to compact it. The electrode

plate was placed in the vacuum oven and heated under temperature of

80oC for 8 hrs. Then the weight of the electrode plate was measured.

3.2.4.3 Assembly of the Coin-Type Cell

The prepared electrode (diameter of 10 mm) and separator

(diameter of 18 mm, Celgard, Hoechst, U.S.A.) were put into the

argon-filled glove box (82-2 Spez, MacPlex, Switzerland). Lithium foil

(thickness of 0.18 mm, 99%, FMC, U.S.A.) was punched into round plate

(diameter of 12 mm) as the anode in the glove box. 2032 coin cells were

assembled with the components of the cell and 1M LiPF6 in EC-DEC-PC

(1:1:1 vol.) (Tomiyama, Japan) as electrolyte in the glove box. The parts


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Figure 3.6.The coin-type cell fabrication.


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3.3.4 Filtration Experiments Apparatus

The filtration experiments were conducted in the apparatus as

shown in Figure 3.8. The filtration experiments used aspirator (TOKYO

RLKAKLAL CO.), Micro-filtration (Techologies, INC) apparatus and

500 ml filter flask (RYREX). During the procedure of filtration, glass

microfiber filter (0.2/47mm, ADVNTEC, Japan) was used as the filter

paper for each filtration process.

3.4 Characteristic Analysis of Cathode Active Material

3.4.1 X-Ray Diffraction Analysis

X-ray diffraction was used to obtain the structure and composition

of crystalline materials. Wide-angle X-ray diffractograms measurements

were performed at room temperature (ca. 25oC) on a Shimadzu

XRD-6000 X-ray diffractometer (operation at 40 kV and 30 mA) with

graphite-monochromatized Cu K radiation (=1.5418). The scanning

rate was 1

/min over a range of 2=10-80

. Measurements were

performed with film specimens of about 0.1 mm in thickness.

3.4.2 Composition Determination

3.4.2.1 Atomic Adsorption Spectroscopy Analysis

Atomic Adsorption Spectroscopy (AAS Model 3000, Varian) was


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Figures 3.8. Schematic diagram of filtration apparatus.

a

bc

a. Micro-filtration apparatus

b. filter flask

c. aspirator


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Optima 2100 DV, Perkin Elmer instruments, U.S.A.) by dissolving

weighted powders (about 1 g) in concentrated HCl solution at 90oC for 30

minutes and diluting to appropriate concentration with distilled water

after cooling to room temperature. Standard solutions were prepared for

calibration and concentration determination.

3.4.3 Capacity Retention Studies

The assembled 2032 coin-type cells were used for the capacity

retention test at 30oC by using a home-made battery tester. The testing

was performed galvanostatically with the cut-off charge-discharge

potentials ranging between 3 and 4.3 V with C/10 rate.

C rate (3-1)

LiMn2O4 and LiCoO2 have the theoretical capacities about 147 and 280

mAh/g, respectively.

1000capacityltheoreticaweightofmaterialactivecathode =


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CHAPTER 4

RESULTS AND DISCUSSION

4.1 Leaching Process

4.1.1 Simulated Experiment of Leaching Process

Theoretically, only LiCoO2, LiMn2O4 and LiCo1/3Ni1/3Mn1/3O2 are

soluble constituents in battery scraps for hydrochloric acid solution with

lower concentration range. In order to reduce the volatilization pollution

caused by reactants, hydrochloric acid with suitable concentration was

chosen as a more suitable leaching reagent as compared to sulfuric acid

and nitric acid. From the standpoint of price of the leaching agent and

investment cost, hydrochloric acid would be a better leaching reagent

than hydroxylamine hydrochloride (Zhang et al., 1998). The LiCoO2,

LiMn2O4 and LiCo1/3Ni1/3Mn1/3O2 with HCl reaction, respectively are as

follows:

4LiCoO2 + 12HCl 4LiCl + 4CoCl2 + 6H2O + O2 (4-1)

4LiMn2O4 + 20HCl 4LiCl + 8MnCl2 + 10H2O + 3O2 (4-2)

12LiCo1/3Ni1/3Mn1/3O2 + 36HCl 12LiCl + 4MnCl2 + 4CoCl2 +

4NiCl2+ 18H2O + 3O2 (4-3)

To obtain the optimum conditions for the leaching of cathode active


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materials of LiCoO2, LiMn2O4 and LiCo1/3Ni1/3Mn1/3O2, several sets of

leaching experiments were carried out that included various hydrochloric

acid concentrations (CHCl), leaching temperature (T), leaching time (t) and

solid-to-liquid ratio (S/L).

4.1.1.1 Hydrochloric Acid Concentrations

Figures 4.1 to 4.3 show the effect of hydrochloric acid

concentration on leaching of cathode active materials: LiCoO2 (A),

LiMn2O4 (B) and LiCo1/3Ni1/3Mn1/3O2 (C) with one hour leaching time,

solid-to-liquid ratio of 1/50 g/ml and 80oC leaching temperature. It

indicates that the leaching efficiencies of lithium, cobalt, nickel and

manganese are relatively low at lower hydrochloric acid concentration. It

is evident that the leaching of cathode active material is enhanced with

the increase of hydrochloric acid concentration (Zhang et al., 1998). Over

99 percentages of lithium, cobalt, nickel and manganese can be leached

when hydrochloric acid concentrations are over 4M. Thus, hydrochloric

acid concentration of 4M is chosen as the optimum leaching

concentration.

4.1.1.2 Leaching Temperature

Figures 4.4 to 4.6 show the effect of leaching temperature on


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81

0 1 2 3 4 5 60

20

40

60

80

100

LP,

%

CHCl

, M

Co

Li

Figure 4.1. Effect of hydrochloric acid concentration on

leached percent of cathode active material, LiCoO2 (A) with

t = 1h, S/L = 1/50 g/ml and T=80 oC.


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82

0 1 2 3 4 5 60

20

40

60

80

100

LP,

%

CHCl

, M

Mn

Li

Figure 4.2. Effect of hydrochloric acid concentration on

leached percent of cathode active material, LiMn2O4 (B) with t

= 1h, S/L = 1/50 g/ml and T=80 oC.


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100/152

84

55 60 65 70 75 800

20

40

60

80

100

LP,

%

T,oC

Co

Li

Figure 4.4. Effect of leaching temperature on leached percent of

cathode active material, LiCoO2 (A) with t = 1h, S/L = 1/50

g/ml and CHCl=4M.


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55 60 65 70 75 800

20

40

60

80

100

T,oC

LP,

%Mn

Li


cathode active material, LiMn2O4 (B) with t = 1h, S/L = 1/50

g/ml and CHCl=4M.


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86

55 60 65 70 75 800

20

40

60

80

100

LP,

%

T,oC

Co

Ni

Mn

Li


cathode active material, LiCo1/3Ni1/3Mn1/3O2 (C) with t = 1h,

S/L = 1/50 g/ml and CHCl=4M.


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leaching of cathode active materials LiCoO2 (A), LiMn2O4 (B) and

LiCo1/3Ni1/3Mn1/3O2 (C) with 1h leaching time, solid-to-liquid ratio of

1/50 g/ml and 4M hydrochloric acid concentration. It indicates that the

leaching efficiency of lithium, cobalt, nickel and manganese is relatively

low at lower leaching temperature. The leaching efficiency increases with

the increase of leaching temperature. When temperature is higher than 80

oC, over 99 percentages of lithium, cobalt, nickel and manganese are

leached.The increase of temperature enhances remarkably the leaching of

the metals (Zhang et al., 1998). Thus, leaching temperature of 80 oC is

chosen as the optimum temperature. Under this leaching temperature,

almost all of the lithium, cobalt, nickel and manganese can be leached

out.

4.1.1.3 Leaching Time

The effect of leaching time on the leaching percent of cathode

active materials LiCoO2 (A), LiMn2O4 (B) and LiCo1/3Ni1/3Mn1/3O2 (C)

with leaching temperature of 80oC, solid-to-liquid ratio of 1/50 g/ml and

4M hydrochloric acid concentration is presented in Figures 4.7 to 4.9. It

is seen that the leached cathode active material is increased with the

increase of leaching time (Nan et al., 2006), and about 99 percentages


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0 1 2 3 40

20

40

60

80

100

LP,

%

t, h

Co

Li

Figure 4.7. Effect of leaching time on leached percent of

cathode active material, LiCoO2 (A) with CHCl=4M, T=80oC

and S/L = 1/50 g/ml.


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0 1 2 3 4 50

20

40

60

80

100

LP,

%

t, h

Mn

Li


cathode active material, LiMn2O4 (B) with CHCl=4M, T=80o

C

and S/L = 1/50 g/ml.


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0 1 2 3 40

20

40

60

80

100

t, h

LP,

%

Co

Ni

Mn

Li


cathode active material, LiCo1/3Ni1/3Mn1/3O2 (C) with CHCl=4M,

T=80 oC and S/L = 1/50 g/ml.


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lithium, cobalt, nickel and manganese can be leached out after 1 hour. So,

the leaching time of 1 h is chosen in this simulated experiment.

4.1.1.4 Solid-to-Liquid Ratio (S/L)

The leaching behavior with different solid-to-liquid ratio (S/L) is

presented in Figures 4.10 to 4.12 at a fixed condition of hydrochloric acid

concentration 4M, leaching temperature 80oC and leaching time 1h. The

leaching efficiency of metals is decreased with increasing solid-to-liquid

ratio (Lee et al., 2003). High solid-to-liquid ratio is desirable to raise

processing throughput. Yet, a solid-to-liquid ratio higher than 1/50 (g/ml)

yields lower leaching efficiency. Over 99 percentages of lithium, cobalt,

nickel and manganese are readily leached out at a solid-to-liquid ratio of

1/50 g/ml.

In summary, the final optimum operating conditions are determined

as follows: 4M hydrochloric acid solution, 80C leaching temperature, 1

h leaching time, 1/50 g/ml solid-to-liquid ratio. Under these experimental

conditions, almost all of metals from the cathode active materials of

LiCoO2, LiMn2O4 and LiCo1/3Ni1/3Mn1/3O2 can be leached out.

The experimental works using cathode active material of LiCoO2

from China was also shown in Appendix A as a contrast. The


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0.02 0.04 0.06 0.08 0.10

20

40

60

80

100

LP,

%

S/L, g/ml

Co

Li

Figure 4.10. Effect of solid-to-liquid ratio (S/L) on leached

percent of cathode active material, LiCoO2 (A) with CHCl=4M,

T=80 oC and t=1h.


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0.02 0.04 0.06 0.08 0.100

20

40

60

80

100

Mn

Li

LP,

%

S/L, g/ml


percent of cathode active material, LiMn2O4 (B) with CHCl=4M,

T=80 oC and t=1h.


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94

0.02 0.04 0.06 0.08 0.100

20

40

60

80

100

Co

Ni

Mn

Li

LP,

%

S/L, g/ml


percent of cathode active material, LiCo1/3Ni1/3Mn1/3O2 (C) with

CHCl=4M, T=80oC and t=1h.


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95

experimental results show the same trend.

4.1.2 Leaching Process for the Mixture

Leaching process using the mixture of cathode active materials of

LiCoO2, LiMn2O4 and LiCo1/3Ni1/3Mn1/3O2 is 1:1:1 in weight ratio. Table

4.1 shows the result of leaching percent with different metals. The

mixture of LiCoO2, LiMn2O4 and LiCo1/3Ni1/3Mn1/3O2 is leached with 4M

hydrochloric acid solution, 80 oC leaching time, 1 h leaching time and

1/50 g/ml solid-to-liquid ratio. Under these experimental conditions,

99.5% cobalt, 99.9% lithium, 99.8% nickel and 99.8% manganese are

readily leached out.

4.2 Recovery Materials Process

The recovery materials process includes sedimentation reaction,

precipitate of manganese, nickel, cobalt and lithium.

4.2.1 Sedimentation Reaction

The recovery material, i.e., valuable metal is selectively

precipitated in its stable hydroxide form as a function of the pH value,

according to its values of solubility product as indicated in Table 4.2

(James and Speight, 2005). Sodium hydroxide solution (1M) is added

onto the 4M hydrochloric acid leach liquor until pH reaches a certain


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Table 4.1. Leached percent of different metals in the mixtiue (LiCoO2:

LiMn2O4:LiCo1/3Ni1/3Mn1/3O2 =1:1:1 in weight ratio) with CHCl=4M,

T=80 oC, S/L=1/50 g/ml and t=1h

Metal Li Co Ni Mn

Leached percent (%) 99.9 99.5 99.8 99.8


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Table 4.2. Solubility products of chemical compounds (James and

Speight, 2005)

Compound Formula Ksp

Cobalt Carbonate CoCO3 1.410-13

Lithium Carbonate Li2CO3 2.510-2

Manganese Carbonate MnCO3 2.3410-11

Nickel Carbonate NiCO3 1.4210-7

Cobalt Hydroxide (II) Co(OH)2 5.9210-15

Cobalt Hydroxide (III) Co(OH)3 1.610-44

Manganese Hydroxide Mn(OH)2 1.910-13

Nickel Hydroxide Ni(OH)2 5.4810-16


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value. Figure 4.13 shows the effect of pH value on recycle percent of

leach liquor of lithium, cobalt, manganese and nickel. Consequently,

precipitation of manganese begins at pH value of 1 and precipitates

completely at pH value of 12. Precipitation of nickel begins at pH value

of 2 and completely at pH value of 7. Precipitation of cobalt begins at pH

value of 3 and completely at pH value of 10. Lithium does not precipitate

with different pH values because lithium is not reacted with hydroxide

ion (Atlas of Elechemical Equilibria in Aqueous Solution, 1974).

4.2.2 Precipitate of Manganese

The manganese in the leach liquor is a redox reaction selectively

and nearly completely with a potassium permanganate reagent. The redox

reaction is described as follows:

3Mn2+ + 2MnO4- + 2H2O 5MnO2 + 4H

+ (4.4)

The effect on the precipitate of manganese is investigated for a

given set of variables as: pH value, molar ratio of Mn++

to KMnO4, and

temperature.

4.2.2.1 pH Value

Separation of manganese from lithium, cobalt and nickel from the

hydrochloric acid leach liquor is performed by employing redox reaction.


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99

0 2 4 6 8 10 12 140

20

40

60

80

100

RP,

%

pH

Co

MnNi

Li

Figure 4.13. Effect of pH value on recycle percent of leach

liquor of cobalt, manganese, nickel and lithium.


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100

If potassium permanganate reagent is directly input to hydrochloric acid

leach liquor, there is no precipitate, because hydrochloric acid leach

liquor is excessively acidic. Therefore, the KMnO4 reagent is input drop

by drop after changing the pH value. Figure 4.14 shows the effect of pH

value on recycle percent of cobalt, manganese, nickel and lithium with

Mn++: KMnO4=2. It is seen that the precipitate of manganese is enhanced

with the increase of pH value. It is found that the precipitate of

manganese increases rapidly and is completely precipitated when pH=2.

Over 99 percentages of manganese are readily in precipitate at pH=2.

Above pH=2, cobalt and nickel begin to precipitate because the cobalt

and nickel are precipitated in its stable hydroxide form as a function of

the pH. Thus, the final optimum pH value for the manganese redox

reaction is determined as pH=2.

4.2.2.2 Molar Ratio of Mn++to KMnO4 (MRMP), and Temperature

In order to raise the operating capacity, the molar ratio of Mn++

to

KMnO4 in the 4M hydrochloric acid leach liquor should be changed.

Figure 4.15 shows the effect of molar ratio of Mn++ to KMnO4 and

temperature on recycle percent of cobalt, manganese, nickel and lithium

with pH=2. It is obvious that temperatures between 40

o

C and 50

o

C do not


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101

0 1 2 30

20

40

60

80

100

RP,

%

pH

Mn

CoNi

Li

Figure 4.14. Effect of pH value on recycle percent of cobalt,

manganese, nickel and lithium (Mn++ : KMnO4= 2).


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0 2 4 60

20

40

60

80

100

0 2 4 60

20

40

60

80

100

RP,

%

50oC

Mn

CoNi

Li

MRMP

40oC

Mn

Co

Ni

Li

Figure 4.15. Effect of molar ratio of Mn++ to KMnO4 and

temperature on recycle percent of cobalt, manganese, nickel

and lithium (pH=2).


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103

have any significant effect on manganese precipitation. It is therefore

advisable that this treatment should be applied at temperature 40oC as

previously described. The manganese in the leach liquor is precipitated

selectively and nearly completely with a potassium permanganate reagent

at molar ratio of 2, pH=2, then the manganese is recovered as MnO2 and

manganese hydroxide with high purity.

4.2.3 Precipitate of Nickel (Castillo et al., 2002)

Separation of nickel from leach liquor after the recovery of

manganese is performed by employing dimethylglyoxime reagent

(C4H8N2O2). In addition of 28% NH3 into the solution to make nickel as

[Ni(NH3)6]2+, the dimethylglyoxime forms a red solid complex. The

complexation reaction is very selective and quantitative (Castillo et al.

2002). The effect on the recycle percent of nickel is investigated fo

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