Method for Recycling Tantalum from Waste Tantalum Capacitors by

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A method for recycling tantalum from waste tantalum capacitors by chloride metallurgy Bo Niu, Zhenyang Chen, and Zhenming Xu ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.6b01839 • Publication Date (Web): 21 Dec 2016 Downloaded from http://pubs.acs.org on December 28, 2016

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ACS Sustainable Chemistry & Engineering

1

A method for recycling tantalum from waste tantalum capacitors by chloride

2

metallurgy

3

Bo Niu, Zhenyang Chen, Zhenming Xu*

4

School of Environmental Science and Engineering, Shanghai Jiao Tong University,

5

800 Dongchuan Road, Shanghai 200240, People’s Republic of China

6 7 8 9 10 11 12 13

Corresponding author: Zhenming Xu

14

E-mail: [email protected]

15

Tel: +86 21 5474495

16

Fax: +86 21 5474495

17

School of Environmental Science and Engineering

18

Shanghai Jiao Tong University

19

800 Dongchuan Road, Shanghai 200240, People’s Republic of China

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1 ACS Paragon Plus Environment


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ABSTRACT

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The demand for tantalum (Ta) is rapidly increasing due to the manufacture of Ta

25

capacitors (TCs) for electronic devices. With the increasing awareness of

26

environmental protection and conservation of rare metal Ta, recycling of Ta from

27

waste TCs (WTCs) is becoming a hot topic for current society. In this study, an

28

efficient and environment-friendly process for recycling Ta from WTCs by chloride

29

metallurgy (CM) is proposed. In the CM process, the non-toxic FeCl2 is chosen as the

30

chlorination agent. Thermodynamic analysis demonstrates that Ta can selectively

31

react with FeCl2, and the generated TaCl5 can be easily separated and then condensed

32

in the condensation zone. The recovery of Ta can reach 93.56% under the optimal

33

chlorination parameters as follows: heating temperature of 500 oC, FeCl2 addition

34

amount of 50%, holding time for 2 h, and particle size of Ta-rich powder less than

35

0.24 mm. Moreover, the kinetic mechanism is discussed, and the rate-controlling step

36

in the chlorination reaction of Ta is determined by mixed control. No hazardous gas

37

and liquid waste are produced during the whole process. Therefore, this study presents

38

an environment-friendly and promising method for the cyclic regeneration of the rare

39

metal Ta from WTCs.

40

KEY WORDS: Waste tantalum capacitors; tantalum; chloride metallurgy; cyclic

41

regeneration;

42 43 44


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INTRODUCTION Tantalum (Ta) is a rare metal which is chiefly used to manufacture tantalum

47

capacitors (TCs) for electronic products. For example, a mobile phone (3G technology)

48

contains about 36, the motherboard of a notebook (2GHz) 22, a digital camcorder

49

about 13 of these capacitors.1 As the number of electronic products has undergone

50

rapid growth, the global TCs consumption had been raised from 10 billion pieces in

51

2001 to 30 billion pieces in 2013.2 The huge market demand for TCs resulted in

52

increasing tantalum (Ta) resource demand. Currently, the world annual production of

53

Ta is only about 2000 tons, and 42% of Ta consumption (777 t) is used for TCs.1 Due

54

to the strong demand for Ta in capacitor manufacturing, the price of capacitor- grade

55

Ta reached $585/kg in 2016. In addition, Ta and niobium (Nb) are almost always

56

paired together in nature. These metals are difficult to separate because of their similar

57

physical and chemical properties.3 Consequently, large amounts of energy and

58

chemical will be required during the Ta separation and purification processes. Owing

59

to the increasing environmental awareness, it is significant to balance the demand for

60

Ta resource and minimize the impact of Ta processing on the environment.

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The recycling of Ta is an effective approach to balance the demand for Ta

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resource and increase resource efficiency in production.4 In fact, current estimate

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shows that nearly 45 million tons of electronic wastes are generated globally per

64

year,5 and large quantities of waste TCs (WTCs) will be discarded accordingly. The

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WTCs contain about 45 wt% of Ta, which is free of Nb.6 Therefore, WTCs could be

66

considered as high quality Ta resource for recycling. However, the recycling Ta from



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WTCs is difficult due to the coexistence of Ta with several materials - a capacitor

68

consists of a sintered Ta anode, MnO2 or polymer cathode, silver paste and graphite

69

cathode layer, terminals (Fe-Ni), and mold epoxy resin (containing SiO2 powder), as

70

shown in Figure 1. Thus far, several related research such as phase separation,4

71

combustion,6,7 steam gasification with NaOH,8 and chemical treatment6,9 have been

72

done to recover Ta from WTCs in laboratory scale. These methods have palpable

73

effects on Ta recovery, but some problems still exist in the recycling processes. For

74

instance, gas pollutants can be generated in the combustion process and liquid waste

75

will be produced during the chemical treatment. Moreover, the solvent cannot be

76

unlimited cycle used, but this is not mentioned in these papers. Ta anode Ta wire

Ta2O5

MnO2 or Polymer

Graphite Silver paste

Anode terminal

Mold epoxy resin

Cathode terminal

77 78

Figure 1. Schematic illustration of a TC.

79

Chloride metallurgy (CM) has been proved to be a quite promising technology to

80

extract many nonferrous metals from their ores and concentrates.10-12 In the

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chlorination process, valuable metals are converted to their corresponding chlorides

82

and then separated based on the difference in volatility between the metal chlorides.

83

This process does not produce liquid waste and is suitable for industrial large-scale


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production. The chlorination agent has an important role in the CM process. There are

85

some possible chlorination agents such as chlorine (Cl2), hydrogen chloride (HCl),

86

carbon tetrachloride (CCl4), sodium chloride (NaCl), magnesium chloride (MgCl2)

87

and ferrous chloride (FeCl2) etc.10 The gaseous or liquid chlorination agents

88

(including Cl2, HCl and CCl4) are efficient, but the hazardous and corrosive of these

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gaseous or liquid chlorination agents require reactors to be both gases tight and

90

corrosion resistant.12 The metal chloride salts are more environment-friendly, since the

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chlorination reaction of metals using the chloride salts will not generate waste gases

92

and the process has low demand to the apparatus. Some rare earth elements in NdFeB

93

magnet and the rare metal titanium in metal scrap have been successfully extracted

94

using chloride salts (MgCl2 and FeCl2).13-15 To the best of our knowledge, however,

95

little research about recycling Ta from WTCs using chloride salts were carried out.

96

In this study, an effective and environment-friendly CM process for recycling Ta

97

from WTCs was proposed. In the CM process, the non-toxic FeCl2 was chosen as the

98

chlorination agent. The effect of chlorination parameters (such as reaction temperature,

99

holding time, FeCl2 adding amount, etc) on the Ta recovery rate were systematically

100

investigated. In addition, the thermodynamics and kinetic of the chlorination process

101

were analyzed. This study provides a theoretical foundation for recycling Ta from

102

WTCs and also puts forward an environment-friendly and efficient way for resource

103

utilization of WTCs.

104



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EXPERIMENTAL

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Materials. FeCl2 (99.5%, Aladdin) was chosen as the chlorinating agent, and

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argon (Ar, 99.99% purity) was used as the shielding gas. The WTCs used in this study

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were provided by Yangzhou Ningda Noble Metal Co., Ltd. (China) and Shanghai Xin

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Jinqiao Environmental Protection Co., Ltd. (China). The major compositions of the

110

WTCs are listed in Table 1. About 20 g of WTCs were heated to 600 oC under Ar to

111

remove the organic materials such as the mold epoxy resin. During the pyrolysis

112

process, oil was gathered by a condenser, and gas was collected by a gas bag. The

113

schematic illustration of the pyrolysis equipment was shown in Figure S1 of

114

Supporting Information (SI). After pyrolysis treatment, Ni-Fe terminals were

115

separated by magnetic separation. Then, the residues were crushed and classified into

116

fractions of < 0.24, 0.24 - 0.45, 0.45 - 0.6 and 0.6 - 0.8 mm, respectively. The content

117

of Ta in the Ta-rich powder is shown in Table 2. The Ta-rich powder was used in this

118

experiment.

119

Apparatus. The chloride metallurgy (CM) experiments were conducted in the

120

quartz tube furnace, as shown in Figure 2. The main body consisted of a body of

121

furnace (chamber dimension is Φ 40 mm × 600 mm), a quartz tube reactor (Φ 35 mm

122

× 800 mm), a gas supply system, and a temperature controller. The middle part of the

123

quartz tube is the heating zone and the two ends of the tube far away from the heating

124

zone were condensation zones.

125 126


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128

Table1 Main composition of the WTCs used in this study. Composition

Ta

organics

SiO2

Ni

Fe

Ag

Content

35.99 ±

11.21 ±

44.78 ±

6.10 ±

1.40 ±

0.48 ±

(wt %)

0.40

0.15

0.51

0.08

0.03

0.03

Table 2 The content of Ta in different particle sized Ta-rich powders. Particle size (mm)

< 0.24

0.24 - 0.45

0.45 - 0.6

0.6 - 0.8

Content (wt %)

60.28 ± 0.57

50.32 ± 0.36

43.48 ± 0.45

39.16 ± 0.28

129

130 131

Figure 2. Schematic illustration of the quartz tube furnace.

132

Methods. In a typical run, Ta-rich particles and FeCl2 powder were blended well

133

with a certain mass ration in a quartz boat, and put into the quartz tube. Ar gas was

134

passed through the reactor with a flow rate of 300 ml/min. The samples were heated

135

from room temperature to the preset temperature. After reaction for a period of time,

136

the samples were cooled to room temperature, and the residues were taken out to

137

calculate the recovery rate. The recovery rate of Ta was calculated by the following

138

formula: 7 ACS Paragon Plus Environment


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R = M − M⁄M × 100%

(1)

Where, M0 and M are the initial and remaining amount of Ta, respectively.

141

Analysis. The content of metals in the raw material and the solid product were

142

analyzed by inductively coupled plasma-mass spectrometry (ICP-MS, Agilent 7500a,

143

Agilent Corporation, US). The content of SiO2 and organics in WTCs were examined

144

by X-ray Fluorescence Spectrometer (XRF-1800, Shimadzu, Japan) and combustion

145

method.16 The crystal structure of products was identified by X-ray diffraction (XRD,

146

D8 ADVANCE, BRUKER, Germany) with Cu Kα radiation. All the measurements

147

were repeated three times, and only the mean values were reported.

148 149

RESULTS AND DISCUSSION

150

Thermodynamic analysis. Prior to the experimental study, the reactions between

151

FeCl2 and components in Ta-rich particles are discussed from thermodynamic

152

viewpoints. Figure 3a shows the Gibbs free energy variation of the reactions at 100 -

153

800 oC (the thermodynamic data were calculated by HSC Chemistry 5.0). It is obvious

154

that Ta can selectively react with FeCl2 above 380 oC. However, the reactions between

155

FeCl2 and other components such as Ta2O5, SiO2 and Ag will not occur because of the

156

positive free energy values. It indicates that it is possible to extract Ta from the Ta-rich

157

powder through chemical reaction. The chemical reaction involved in the extraction

158

of Ta with FeCl2 is as follows:

159 160

2 + 5 , = 2 + 5

(2)

For chloride metallurgy (CM), selective chlorination reaction is prerequisite, and


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161

the separation of different metal chlorides is crucial. The separation of chlorides from

162

each other is achieved by utilizing their different vapor pressures at certain

163

temperature. The metal chloride with high vapor pressure and low boiling point can

164

be separated through distillation or sublimation from other chlorides, and then be

165

recovered through condensation at certain temperature.10 Figure 3b shows the vapor

166

pressure of TaCl5 and FeCl2 as a function of temperature. The vapor pressure

167

calculations are listed in Table S1 of Supporting Information (SI). As shown in Figure

168

3b, the vapor pressure of TaCl5 is substantially higher than that of FeCl2. Moreover,

169

the boiling points of TaCl5 and FeCl2 at standard atmospheric pressure are 234 oC and

170

1026 oC, respectively. It means that TaCl5 can be evaporated into the gas phase, while

171

the excess FeCl2 will remain in the residues, with the chlorination temperatures

172

between 380 - 1000 oC.

173

Based on above thermodynamic analysis, we can draw a conclusion that, when

174

the chlorination temperature is between 380 - 800 oC, only Ta in the Ta-rich powder

175

can react with FeCl2, and generate gas phase TaCl5. The generated TaCl5 can be easily

176

separated from the reactants and subsequently condensed in the condensation zone.



800 Ta2O5(s)+5FeCl2(s,l)=2TaCl5(g)+5FeO(s)

(a)

600

∆G (kJ/mol)

400 SiO2(s)+2FeCl2(s,l)=SiCl4(g)+2FeO(s) 200 2Ag(s)+FeCl2(s,l)=2AgCl(s)+Fe(s) 0 2Ta(s)+5FeCl2(s,l)=2TaCl5(g)+5Fe(s)

-200 100

200

300

400

500

600

700

800

o

177

Temperature ( C) 5

10

(b)

4

10 Vapor pressure (Pa)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

FeCl2 TaCl5

3

10

2

10

1

10

0

10

0

200

400

600

800

1000

o

178

Temperature ( C)

179

Figure 3 (a) Gibbs free energy variations of the reactions between FeCl2 and Ta-rich

180

particles at 100-800 oC; (b) vapor pressure of TaCl5 and FeCl2 as a function of

181

temperature.17

182

Effect of reaction conditions on Ta recovery rate. Tantalum (Ta) is the target

183

element of this study. In order to obtain the maximum Ta recovery rate, the effects of

184

FeCl2 adding amount, chlorination temperature, holding time and particle size of

185

Ta-rich powder on the recovery rate of Ta were investigated.

186

Figure 4a shows the relationship between Ta recovery rate and FeCl2 adding

187

amount (temperature: 500 oC, holding time: 30 min, particle size of Ta-rich powder: 10 ACS Paragon Plus Environment

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less than 0.24 mm). The recovery rate of Ta increased from 70.36% to 90.84% with

189

increasing the FeCl2 adding amount from 40 wt% to 50 wt%. But, the recovery rate

190

began to decrease when further increasing the adding amount of FeCl2. This indicates

191

that the excessive FeCl2 could impede the chlorination process for Ta. Therefore,

192

adding 50 wt% of FeCl2 was sufficient for the chlorination reaction of Ta. 92

95

(b)

(a) 90

Recovery rate (%)

Recovery rate (%)

90

85

80

88

86

75 84

70

65

82

40

45

193

50

55

60

400

450

FeCl2 adding amount (wt%)

500

550

600

o

Temperature ( C)

94

100

(c)

(d) 80

Recovery rate (%)

93 Recovery rate (%)

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92

40

20

91

30

194

60

60

90

120

150

0

180

< 0.24

0.24~0.45

0.45~0.6

0.6~0.8

Particle size of Ta-rich powder (mm)

Holding time (min)

195

Figure 4. Effects of (a) FeCl2 addition amount, (b) temperature, (c) holding time and

196

(d) particle size of Ta-rich powder on the recovery of Ta.

197

The relationship between Ta recovery rate and chlorination temperature is shown

198

in Figure 4b (FeCl2 adding amount: 50 wt%, holding time: 30 min, particle size of

199

Ta-rich powder: less than 0.24 mm). It shows that the effect of temperature on the

200

recovery rate of Ta is significant. The recovery of Ta could reach to 83.78%, when the 11 ACS Paragon Plus Environment


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201

chlorination temperature was 400 oC. It suggests that Ta can be started to chlorinate

202

by FeCl2 at this temperature, which is in accord with the above thermodynamic

203

analysis (the temperature is above 380 oC). The highest recovery rate appeared at 500

204

o

205

indicates that excess temperatures will not facilitate the chlorination reaction of Ta.

206

Therefore, controlling the chlorination temperature is an essential condition for a

207

higher Ta recovery rate.

C, and then the recovery rate decreased with the increase of temperature, which

208

The relationship between Ta recovery rate and holding time is shown in Figure

209

4c (FeCl2 adding amount: 50 wt%, temperature: 500 oC, particle size of Ta-rich

210

powder: less than 0.24 mm), which shows that the recovery rate of Ta can reach up to

211

90.84% at 30 min. A higher recovery rate could be obtained at 120 min and the

212

recovery rate of Ta was 93.56%. Thus, holding time for Ta chlorination process was

213

considered as 120 min.

214

Figure 4d shows the relationship between Ta recovery rate and particle size of

215

Ta-rich powder (FeCl2 adding amount: 50 wt%, temperature: 500 oC, holding time:

216

120 min). The results suggested that the recovery rate of Ta increased with reducing

217

the particle size. When the particle size of the Ta-rich powder was less than 0.24 mm,

218

the optimized recovery rate of Ta could be obtained.

219

The above experiments show that the recovery rate of Ta can reach 93.56% at the

220

conditions of FeCl2 adding amount: 50 wt%, chlorination temperature: 500 oC,

221

holding time: 120 min and particle size of Ta-rich powder: less than 0.24 mm.

222

Therefore, these conditions were considered as the optimal chlorination parameters


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223

for Ta-rich powder.

224

Characterization of reaction product. After the best conditions were

225

confirmed, the product under optimal conditions was analyzed. Figure 5a shows the

226

image of the condensed product, which presents white deposits on the inner wall of

227

the quartz tube. The white deposits were scraped off (Figure 5b) and analyzed by

228

XRD. Figure 5c shows the XRD pattern of deposits (condensing product). As shown

229

in Figure 5c, the peaks corresponding to tantalum oxide instead of TaCl5 were

230

observed, since TaCl5 is prone to hydrolysis and transforms into oxides of tantalum

231

when exposed in the air. Actually, TaCl5 will be inevitably exposed to air during the

232

collection process and preparation of the XRD measurement sample. The formed

233

tantalum oxide will be favorable due to the properties of easy storage and usage. In

234

addition, no other phases were observed in Figure 5c, demonstrating that the tantalum

235

oxide had a high purity. The ICP-AES result indicated that the purity of tantalum

236

oxide was over 99%.

237 4500 4000

(a)

(c)

Tantalum Oxide: JCPDF (19-1299)

♣

3500 Intensity (Counts)

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(b)

3000

♣

2500 2000

♣

1500 ♣

1000

♣ ♣

500

♣

1cm

10

20

30

238 239

♣

♣

0 40

50

60

70

80

2 Theta (Degree)

Figure 5 (a) The image of the condensed product in one end of the quartz tube, (b)



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240

the image of deposits scraped from the quartz tube, and (c) XRD pattern of the

241

deposits.

242

Kinetic analysis. Many kinetic equations of the solid - solid reactions are

243

reported in the literatures.18,

244

determined by chemical reaction control, ash diffusion control and the mixed

245

control.20 To further understand the chlorination process, the kinetic equations were

246

used to determine the rate-controlling step. The mathematical formulas for the

247

chemical reaction control, ash diffusion control, and mixed control are investigated in

248

equations 3, 4 and 5, respectively.

249

19

Generally, the solid - solid reactions could be

1 − 1 − / = !

(3)

250

1 − 2 ⁄3 − 1 − / = !

(4)

251

= #! +

(5)

252 253

Where R is the recovery rate of Ta; K is the reaction rate constant; t is the chlorination time; and C is a constant.

254

The analysis results of the chlorination process are shown in Figure 6. The best

255

correlation of the experimental data for the chlorination process of Ta was obtained by

256

equation 5, which indicates that the kinetic model for the chlorination reaction of Ta

257

could be described as the mixed control (chemical reaction and ash diffusion controls).

258

The chlorination process can be explained as the follows. Firstly, Ta will react with

259

FeCl2 under certain temperature, and the chlorination reaction proceeded with time

260

prolonging. During the chlorination process, the reaction residues were also generated

261

and then formed an ash layer (mainly Fe, as shown in Figure S2 of SI). As the reaction


Page 15 of 21

262

progress, the reaction residues gradually increased, leading to the thickening of the

263

ash layer. The ash layer would provide a barrier of the reactions between Ta and FeCl2.

264

Meanwhile, the gaseous products TaCl5 penetrated through the ash layer and reactants

265

(Ta rich particle and FeCl2), which was facilitated to the chlorination reaction. When

266

Ta or FeCl2 was exhausted, the reaction is terminated. Therefore, the mixed control

267

could be considered as the chlorination rate-controlling step. For the higher recovery

268

of Ta, decreasing the particle size of reactants and increasing the contact area between

269

reactants can be beneficial to the reaction (Figure 4d). 0.220

0.60

(a)

0.215

(b)

0.59 2/3

0.210

1-2R/3-(1-R)

1/3

1-(1-R)

0.58

0.57 Equation y = a + b*x Adj. R-Square 0.85724

0.56

0.205 0.200 Equation

B

Intercept

B

Slope

4.31251E-4

Value

8.62166E-5

0.190

30

60

90

120

0.88926

0.195

0.55

270

y = a + b*x

Adj. R-Square

Value Standard Error 0.54289 0.00858

150

30

B

Intercept

B

Slope

60

Time (min)

90

Standard Error

0.18779

0.00364

2.10379E-4

3.65559E-5

120

150

Time (min)

94.0 93.5

(c)

93.0 R

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92.5 92.0 Equation

y = a + b*x

91.5

Adj. R-Squar

91.0

B

Intercept

84.6948

0.6414

B

Slope

1.81688

0.14592

0.97469 Value

90.5 3.2

271

3.6

4.0

4.4

Standard Error

4.8

5.2

lnt

272

Figure 6. Kinetic plots of (a) chemical reaction control, (b) ash diffusion control, and

273

(c) mixed control of the chlorination process for Ta at 500 oC.

274

Environmental comparison with other processes. As stated in the introduction,



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275

recycling Ta from WTCs is an effective approach to balance the demand for Ta

276

resource for social and environmental need. Therefore, some research has been done

277

to recycle Ta from WTCs. In the existing research, WTCs are most treated via

278

pyrometallurgy (high-temperature combustion) and hydrometallurgy including many

279

wet steps to extract Ta. However, gas pollutants and liquid waste will be inevitably

280

generated during the combustion and chemical treatment. An overview of the

281

comparison between the proposed route and other processes for WTCs recycling is

282

given in Table 3. Therefore, the proposed CM technology in this study can be

283

regarded as an environment-friendly and promising process for recycling Ta from

284

WTCs due to its excellent environmental and economic benefits.

285 286

CONCLUSIONS

287

An efficient and environment-friendly chloride metallurgy (CM) process has

288

been proposed for the recovery of tantalum (Ta) from waste tantalum capacitors

289

(WTCs). Compared to other hazardous and corrosive chlorination agents (Cl2, HCl

290

and CCl4), the non-toxic FeCl2 was chosen as the chlorination agent in this study.

291

Thermodynamic analysis demonstrates that Ta can selectively react with FeCl2, and

292

the generated TaCl5 can be easily separated and then condensed in the condensation

293

zone. The recovery of Ta could reach to 93.56% under the optimal chlorination

294

parameters as follows: heating temperature of 500 oC, FeCl2 addition amount of 50%,

295

holding time for 2 h, and particle size of Ta-rich powder less than 0.24 mm. In

296

addition, the kinetic mechanism is discussed, and the rate-controlling step in the


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297

chlorination reaction of Ta is determined by the mixed control (chemical reaction and

298

ash layer diffusion controls). No hazardous gas and liquid waste are produced during

299

the whole process. Therefore, this study presents an environment-friendly and

300

promising technology for the cyclic regeneration of the rare metal Ta from WTCs.

301 302

Table 3 Overview of comparison between the proposed route and other processes for

303

WTCs recycling Method processing steps

CM treatment chlorination extraction

Pyrometallurgy

Hydrometallurgy

calcination

many wet processing steps

Ta recovery rate

> 90%

> 90%

> 90%

energy consumption

lower energy consumption than pyrometallurgy

high energy consumption

___

time consumption

high efficiency

high efficiency

long periods of time

chemical use

only FeCl2 consumed

___

large amount of mineral acid and oxalate organic solvent strong alkali

emissions

Pyrolysis oil and gas were collected and could be recycled as energy resources

gaseous pollutant

large amount wastewater and acid

304 305 17 ACS Paragon Plus Environment


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306

ASSOCIATED CONTENT

307

Supporting Information

308

The Supporting Information is available free of charge on the ACS Publications

309

website. Schematic illustration of the pyrolysis equipment; XRD patterns for the

310

residue after CM; Saturated vapor pressure calculation of TaCl5 and FeCl2.

311

ACKNOWLEDGMENTS

312

This work was supported by the National Natural Science Foundation of China

313

(51534005).

314

REFERENCES

315

1

Angerer, T.; Luidold, S.; Antrekowitsch, H. Recycling potentials of the two

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Spitczok von Brisinski, L.; Goldmann, D.; Endres, F. Recovery of metals from tantalum capacitors with ionic liquids. Chem. Ing. Tech. 2014, 86, (1-2), 196-199.

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Met. Rev. 1997, 16, (4), 211-237. 11 Kanari, N.; Allain, E.; Joussemet, R.; Mochón, J.; Ruiz-Bustinza, I.; Gaballah, I.

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Frade, J. R.; Cable, M., Theoretical solutions for mixed control of solid state reactions. J. Mater. Sci. 1997, 32 (10), 2727-2733.

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For Table of Contents Use Only

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A method for recycling tantalum from waste tantalum capacitors by chloride

374

metallurgy

375

Bo Niu, Zhenyang Chen, Zhenming Xu*

376 377 378

Recycle WTCs

379

1cm Tantalum oxide

380 CM

381 382 383 384 385

Synopsis

386

Recycling Ta from WTCs by chloride metallurgy can achieve the sustainable

387

utilization of Ta resource and reduce the pollution.

388 389 390


Method for Recycling Tantalum from Waste Tantalum Capacitors by

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