EVALUATION OF SPENT ALKALINE AND ZINC-CARBON BATTERY RECYCLING

USING

ASCORBIC ACID, ACTIVATED CARBON AND GUAR MEAL REDUCTANTS

S. Kursunoglu and M. Kaya*

Eskisehir Osmangazi University, Mining Engineering Department,

26480, Eskisehir, Turkey

(*Corresponding author: mkaya@ogu.edu.tr)

EVALUATION OF SPENT ALKALINE AND ZINC-CARBON BATTERY RECYCLING USING

ASCORBIC ACID, ACTIVATED CARBON AND GUAR MEAL REDUCTANTS

ABSTRACT

The aim of this study was to investigate the effectiveness of Ascorbic (C6H8O6) Acid (AA),

Activated Carbon (AC) and Guar Meal (C6H12O6) (GM) as a reductant for the simultaneous complete

dissolution of zinc (Zn) and manganese (Mn) from a spent and mixed Zinc-Carbon (Zn-C) and alkaline

battery powders in sulphuric acid (H2SO4) leaching. AA was tested previously as a reductant by other

researchers while AC and GM were tested as a reductant for the first time in battery recycling. The effects

of H2SO4 concentration, AA/AC/GM dosages, reaction temperature and leaching time on the Zn and Mn

dissolutions were investigated according to 2k full factorial experimental design and Central Composite

Design (CCD) technique; then, a simple optimization study was carried out for comparing the reductants.

The optimum reductive acid leaching conditions for AA were determined at 3 hours leaching time, 70°C

leaching temperature, 0.5M H2SO4 concentration, 13 g/L AA dosage, 1/20 g/mL solid/liquid (S/L) ratio and

200 rpm stirring speed. Under these conditions, the dissolution efficiencies were 99.9% for Zn and 99.3%

for Mn. The best reductive acid leaching conditions for AC were determined at 3h leaching time, 80oC

leaching temperature, 1M H2SO4 concentration, 3 g/L AC dosage and 400 rpm mixing speed. Under above

conditions, Zn and Mn dissolutions were not complete. At 2M H2SO4 concentration, 10 g GM dosage,

700C leaching temperature, 200 rpm stirring speed, 1/20 g/mL solid/liquid (S/L) ratio and 3 hours leaching

time, full dissolution of both Zn and Mn was achieved.

As a result, three different reductants were evaluated in this study for complete simultaneous Zn

and Mn dissolutions. This paper also compared present test results with previous spent battery recycling

studies for Zn and Mn dissolutions. Full valuable metals dissolutions from spent batteries were achieved at

low H2SO4 concentrations with AA and high concentrations with GM. Selective precipitations of Zn and

Mn from acid solutions were carried out using NaOH and KOH. Using 3M NaOH as precipitating agent at

room temperature and at pH 8; 95.4% of Zn and at pH 10; 93.7% of Mn were precipitated from the leach

solution. Under the same conditions, using 3 M KOH at pH 8; 91.6% of Zn and at pH 10, 96.4% of Mn

were precipitated. Based on the experimental results obtained, an appropriate flow sheet was proposed to

recover both Zn and Mn.

KEYWORDS

Spent battery recycling, ascorbic acid, activated carbon, guar meal, reductive acid leaching

INTRODUCTION

In the last three decades, the consumption of batteries has increased because of the versatility, low

maintenance, reduced cost and demand from electronics industry. Worldwide annual demand for batteries

is expected to rise at nearly 7%. Disposal of spent batteries represents an increasing environmental problem

in terms of heavy metal contents. The disposal cost of this hazardous material is quite high due to the

limited storage capacity of landfills. Furthermore; for battery production, the recycled secondary products

provide both reduction in production costs and preservation of raw materials (Ferella et.al, 2008). About

11000 t of spent batteries are generated annually in Turkey as a waste material. Since there is no battery

recycling plant in Turkey so far, only 2% of spent batteries can be collected (Kaya and Kursunoglu, 2012).

The recovery of Zn and Mn from various secondary sources like batteries has been an important and

unknown issue in Turkey. The produced Mn from secondary or raw materials is consumed in the

manufacture of batteries, nonferrous alloys and steel making, while Zn is used as plating material, coating

material and alloying elements.

The recovery of metals from spent batteries is becoming essential due to environmental awareness

and imposed regulations. It is also crucial that the proposed recovery process should be environmentally

friendly, simple and suitable for full scale applications. Many proposed pyro/hydro metallurgical recovery

processes have been published in detail (Kaya & Kursunoglu, 2011). The pyrometallurgical method

consists basically of selective volatilization of metals at elevated temperatures followed by condensation.

The examples of such processes are BATREC, SNAM-SAVAN, SAB-NIFE and INMETCO (Salgado

et.al., 2003; Bernardes et.al., 2004; Espinosa et.al., 2004). Generally, pyrometallurgical processes do not

require battery dismantling; however, applied operations are very energy consuming and some emissions

of dust and gases are expected. The hydrometallurgical processes are commonly found more economical

and efficient than pyrometallurgical process (Gega & Walkowiak, 2011). The metal separation routes

based on hydrometallurgical processes are characterized by higher metal selectivity, lower energy

consumption and without air pollution. However, some pretreatment steps are necessary to improve metal

dissolution rates in the aqueous phase like battery sorting, dismantling, magnetic separation etc. The

examples of hydrometallurgical processes are BATENUS (Froehlich & Sewing, 1995), MODIFIED

ZINCEX (Martin et.al., 2001), RECUPLY (Salgado et.al., 2003) and CITRO (Bernardes et.al., 2004).

Recently, numerous studies have been conducted on the recycling of Zn-C and alkaline batteries

using hydrometallurgical process. The aim of those studies was to recover Zn and Mn metals (Salgado

et.al., 2003; Velosa et.al., 2005; Ferella et.al., 2006; Mantuano et.al., 2006; Michelis et.al., 2007, Ferella

et.al., 2008; Furlani et.al., 2009; Sayılgan et.al., 2009; Sayılgan et.al., 2010; Kursunoglu & Kaya, 2013).

For instance, the leaching of alkaline battery powders with 1.0% (v/v) H2SO4 at 90°C for 2 hours leaching

time has resulted on the dissolution of 43% Mn (Salgado et.al., 2003). A similar dissolution result of Mn

(40%) and Zn (100%) oxides was obtained using 0.7% (v/v) H2SO4 at 70°C and 3 hour leaching time (De

Souza et.al., 2001). The aqueous solution obtained from the acid leaching step is sent to a purification step

to separate Zn and Mn. Different types of separation methods can be used such as liquid-liquid extraction

(Salgado et.al., 2003; Mantuano et.al., 2006), electro winning (De Souza et.al, 2004; Tacca & Duarte,

2005), precipitation (Bernardes et.al., 2004; De Michelis et.al., 2007; Sayılgan et.al. 2010). Compared to

liquid-liquid extraction method, for example, precipitation method seems to be a simpler and cheaper

method for both Zn and Mn recoveries (Velose et.al., 2005).

In the present work, the mixed Zn-C and alkaline battery powder is reduced to zinc sulfate and

manganese sulfate by employing AA/AC/GM in H2SO4 solution. The following reactions can be

considered for the dissolution of zinc oxide and manganese dioxide from the mixed Zn-C and alkaline

battery powder. Zn, ZnO and MnO are fully dissolved by H2SO4. Due to formation of MnO2; Mn2O3 and

Mn3O4 are partially dissolved by H2SO4. In order to dissolve MnO2 with H2SO4 a reductant was required.

According to Equation (1), zinc oxide fully dissolves in H2SO4 solution. On the other hand, Equations 2, 3

and 4 indicate that AA/AC/GM can be used to dissolve manganese dioxide in H2SO4 solution.

ZnO + H2SO4 → ZnSO4 + H2O (1)

10MnO2 + 10H2SO4 + C6H8O6 → 10MnSO4 + 14H2O + 6CO2 (2)

2MnO2 + C + 2H2SO4→ 2MnSO4 + 2H2O + CO2 (3)

12MnO2 + 24H+ +C6H12O6 → 12Mn

+ +18H2O +6CO2 (4)

The first purpose of this study was to investigate the effectiveness of AA/AC/GM as a reductant

for the simultaneous complete recovery of Zn and Mn from a mixed Zn-C and alkaline battery powder and

then determine which reductant and which operation conditions are the best for full Zn and Mn dissolution.

The second purpose was to precipitate the Zn and Mn as hydroxides and finally suggest a suitable

hydrometallurgical flow sheet for the spent battery recycling process.

AA and AC are known chemicals in hydrometallurgy. AC and GM were firstly used by the

authors in battery recycling. Guar gum processing varies from plant to plant. When guar seeds are removed

from their pods these are spherical in shape, brownish in color, smaller than pea seeds in size. The gum is

commercially extracted from seeds essentially by a mechanical process of roasting, differential attrition,

sieving and polishing. The seeds are broken and the germ is separated from the endosperm. Two halves of

the endosperm are obtained from each seed and are known as undehusked guar split. When the fine layer

of fibrous material, which forms the husk, is removed and separated from the endosperm halves by

polishing, refined guar splits are obtained. The hull (husk) and germ portion of guar seed are termed as GM

which is a major by-product of guar gum powder processing and is utilized as cattle feed (Mudgil et al.,

2011). It includes 50-55% high protein and this protein is rich in terms of lysine and methionine. This

product contains 10% moisture, 50-55% crude protein, 4% cured oil, 12% fiber, 5% cured ash, 3% cured

cellulose, “O+A” 55% minimum (Oil&Albuminoid) and 50% CHO (NFE). Guar meal is also well

endowed in the way of amino acid such as 26.85% izolosin, 13.01% proline, argine 9,96% arginine and

9.24% glutamic.

EXPERIMENTAL

The mixed AA (R6) and AAA (R3) sizes of Zn-C and alkaline batteries collected from

Osmangazi University spent battery collection bins were used in this study. The batteries were dismantled

in a laboratory hammer crusher. The crushed batteries were screened from a 2 mm sieve to remove

manually steel scraps, plastics and papers. The remaining materials, which were finer than 2 mm, were

used as black battery powder in this study. The moisture content of the battery powder was 7.4% at 105±

5°C. The battery powder was mixed carefully to ensure the homogeneity. Powder samples were ground for

30 min in a laboratory Bond ball mill. The particle size distribution of mill products was determined by

using a particle size analyzer (Malvern, Mastersizer 2000). In the neutral and reductive acid leaching

experiments, 30 minute ground Zn-C and alkaline battery powder mixture was used. The 90% of the

ground powder was finer than 88 µm. The average composition of the mixed Zn-C and alkaline battery

cells is given in Table 1.

Table 1 - Average composition of the mixed Zn-C and alkaline battery cells

Components Powder Steel Paper Plastic Moisture

Wt. (%) 55.29 28.93 6.12 2.25 7.40

The ground powder contains 28.5% Zn and 31.2% Mn. However, differing values of ground

powder content (unwashed) have been reported by other researchers. For example, 21% Zn and 45% Mn

(De Souza et.al., 2001 & De Souza et.al., 2004); 21% Zn and 33% Mn (Velose et.al., 2005), 19% Zn and

36% Mn (De Michelis et.al., 2007) and 9% Zn and 42% Mn (Sayılgan et.al., 2010). These variations in the

feed samples may stem from the use of different types and manufacturers’ batteries in their studies.

The flowchart used in this study for the simultaneous Zn and Mn dissolutions from the mixed AA

and AAA sizes Zn-C and alkaline battery cells is shown in Figure 1. Characterization of the mixed battery

powder was performed using a Bruker AXS D8 Advance X-Ray Diffractometer (XRD), a Philips PW-

2404 X-Ray Fluorescence Spectrometer (XRF), a Thermo Scientific Spectra 3000 Atomic Absorption

Spectrometer, (AAS) and a Varian Inductively Coupled Plasma (ICP). XRD displayed the presence of ZnO,

MnO2, Mn2O3, Mn3O4, KOH, KO2 and C (graphite) in the unwashed (original) powder and of the same

compounds except KOH in the washed (natural water leached) powder similar to De Michelis et.al. (2007)

and De Souza et.al. (2001)’s findings. Semi-quantitative XRF pattern of the unwashed and washed powder

studied are given in Table 2.

Table 2 - Semi-quantitative XRF analysis of the unwashed and washed battery powders

Element (w/w %) Mn Zn K Fe Cl

Unwashed powder 31.16 28.52 2.59 0.77 5.42

Washed powder 32.80 32.92 0.23 0.83 1.29

Figure 1 - Tested flowchart for the simultaneous Zn and Mn recovery from the mixed AA and AAA sizes

Zn-C and alkaline battery cells.

The neutral leaching (i.e. water washing) tests were performed in a 250 mL Erlenmeyer flask,

agitated at 200 rpm using a magnetic stirrer (Advantec TBS 541 PA), immersed in a temperature-

controlled water bath. The neutral leaching tests were carried out at different solid/liquid ratios of 1:10 and

1:20 g/mL. The temperature was maintained at 60°C. Each washing was carried out for 3 h. Glass

condensers were fitted on the Erlenmeyer flasks in order to prevent evaporation. After neutral leaching, the

final solution pHs were measured using a digital pH-meter (Hach, 40d). Figures 2a and 2b show

experimental set up used in the neutral and the reductive acid leaching tests with different reductants.

Figure 2a - Experimental set up used in neutral, preliminary and reductive acid leaching tests with ascorbic

acids (1- Temperature controlled water bath; 2- Magnetic stirrer speed controller; 3- Glass condenser;

4- 250 mL Erlenmeyer flask).

Figure 2b: Experimental set-up for activated carbon and guar gum korma tests (1- Reactor, 2- Mechanical

stirrer, 3- Glass condenser, 4- Temperature controller, 5- Circulating water bath).

The quantitative analysis was carried out under the following conditions: 2 g of washed battery

powder were dissolved in 100 mL of 3M H2SO4 concentration with 10 g/L AA dosage as a reducing agent

in the temperature-controlled water bath at 60°C and 200 rpm. After 5 hour leaching, the sample was

filtered with Whatman 42 filter paper and washed with nitric acid of %5. An aliquot (10 mL) of the leach

liquor was withdrawn and diluted with distilled water by 1:100, and then analyzed by AAS and ICP for Mn

and Zn. The result of the quantitative analyses showed that the battery powder was composed of 34.75%

Mn and 34.05% Zn. The same quantitative analysis procedure was firstly used by Kaya & Kursunoglu

(2011); De Michelis et.al. (2007); Ferella et.al. (2006); Kaya & Kursunoglu (2011a). All of the chemicals

used in this study were of analytical grade (Merck). The dissolution ratio was calculated from the

percentage of Zn and Mn analyses using the following equation:

Dissolution Ratio (%) = [I/Q]*100 (4)

where I is the instrumental analysis result for Zn and Mn at the end of the reductive acid leaching process

(%), Q is the Zn and Mn quantitative analysis results (i.e. 34.1% Zn and 34.8% Mn).

Reductive Acid Leaching

The effects of H2SO4 concentration, AA/AC/GM dosages, reaction temperature and leaching

time on the Zn and Mn simultaneous dissolutions were investigated according to 2k full factorial

experimental design for AA as a reductant and Central Composite Design (CCD) technique for AC as a

reductant; then, a simple optimization study for complete Zn and Mn dissolutions with GM was carried out

for the determination of the best reductant.

Precipitation

Purification of reductive acid leach solution by precipitation was a simple and cheap method. Zn

and Mn were precipitated from leach solutions using 3M NaOH/KOH at different pH values. Precipitated

materials were analyzed by SEM and SEM-EDX. After the reductive acid leaching step, precipitation tests

were carried out in 1L beakers. These tests were conducted on the filtered leaching solution using optimum

reductive acid leaching test conditions for AA. . A solution of 3M NaOH and KOH was added slowly to

the leach solution to raise the pH up to 12. The pH of the solution was closely controlled during

precipitation tests. A 5 mL sample was withdrawn at determined pH values (3, 6-12), and then the samples

were diluted with distilled water by 1:100. The Zn and Mn concentrations in the diluted solutions were

determined by AAS. After filtration, the solid precipitates remained in the 1L beakers were dried in the

oven at 105°C for 24 hours. The dried solid residues were analyzed by XRD to characterize their

composition.

RESULTS AND DISCUSSION

Neutral Leaching

In the neutral water leaching step, it was found that increasing the S/L ratio from 1/10 to 1/20 did

not significantly change the removal of K (97%) and Cl (76%) ions from the samples. The removal of K

and Cl ions from battery powder mixtures can reduce acid consumption in the subsequent reductive acid

leaching step (De Michelis et.al., 2007; Furlani et.al., 2009). As a result, all neutral leaching tests were

carried out at 1/10 S/L ratio. After neutral leaching, the solution pH value was found to be around 9.0-9.5.

The washed battery powder showed an increase in the amount of Zn and Mn contents, which were about

64% of total weight of the sample.

Preliminary and Reductive Acid Leaching Tests

Figure 3 shows the Zn and Mn dissolutions without any reductant as a function of the H2SO4

concentrations from 0.15 M to 2 M for 3 hours. For all preliminary tests, the S/L ratio, mixing speed,

leaching time and temperature were kept constant at 1/20 g/mL, 200 rpm, 70oC for 3h, respectively. These

conditions were taken from the optimum values of previous studies (Sayılgan et.al., 2009; Sayılgan et.al.,

2010). As it can be seen from Figure 3, increasing the H2SO4 concentration from 0.15 to 1 M increased the

leaching recovery/dissolution of Mn from 39.04% to %58.69 and Zn 96.05% to 99.93%. Zn recovery

decreased slightly at concentrations higher than 1 M. This may be due to precipitation of Zn in the solution.

Mn recovery was drastically lower than Zn; but increased with increasing H2SO4 concentration. Low/dilute

H2SO4 concentration (>0.5 M) is enough for Zn dissolution while high H2SO4 concentration (2M) is

necessary for Mn dissolution. At 2M H2SO4 concentration, 60.53% Mn dissolution was achieved without a

reductant. Since our objective was to dissolve Zn and Mn simultaneously, 2M H2SO4 concentrations were

assumed optimum for Mn dissolution with GM.

0,0 0,5 1,0 1,5 2,0

40

50

60

70

80

90

100

Zinc

Manganese

Leachin

g r

ecovery

, %

Concentration of H2SO

4,, M

Figure 3 - Effect of H2SO4 concentration on dissolution of Zn and Mn without a reductant at 70

oC for 3h

leaching time.

These results showed H2SO4 were very effective on dissolution of Zn and Mn from Zn-C and

alkaline battery powder mixture. These findings are also consistent with the results of previous researchers

such as Sayılgan et.al. (2009); El Hazek et.al. (2006); El Nadi et.al. (2007). Based on these findings and

environmental considerations, low H2SO4 concentrations (i.e. 0.10M and 0.20M) were chosen for reductive

acid leaching tests with AA and high concentrations with AC and GM. In reductive acid leaching tests with

AA, 24 full factorial experimental design with six central point tests (Montgomery, 2001) and with AC,

CCD technique were used. The selected operating variables were H2SO4 concentration, AA/AC/GM

dosage, leaching temperature and time (Table 3).

Table 3 - Factors and levels investigated in reductive acid leaching tests

(solid/liquid ratio of 1:20 g/mL).

Code Variables Level

(-1) low (0) base (+1) high

X1 Sulfuric acid (M)*

Sulfuric acid (M)**

Sulfuric acid (M)***

0.10

0.5

0.15

0.75

0.20

1.0

2.0

X2 Ascorbic acid (g/L)*

Activated carbon (g)**

Guar Meal (g)***

5

1

4

7.5

2

8

10

3

12

X3 Temperature (°C)*

Temperature (°C)**

Temperature (°C)***

30

40 40

60

50

80

70

X4 Time (h)*/**

Time (h)***

1

1

2 3

4

* With ascorbic acid, **With activated carbon, *** With guar meal as a reductant

Table 4 shows the results of reductive acid leaching tests with AA and AC. For AA, 22 and for

AC, 20 tests were performed and maximum simultaneous Zn and Mn dissolutions were obtained at test no:

16 where H2SO4 concentration was 0.2M, AA dosage was 10 g/L, leaching temperature was 50oC and

leaching time was 3 h. AA showed higher metal dissolutions than AC as a reductant. Maximum Mn

dissolution was about 86% and Zn dissolution was 90.2% with the use of AA as a reductant. The use of AC

as a reductant achieved better Mn dissolution than AA. The maximum Mn dissolution of 86.4% was

obtained at 1M H2SO4 concentration, 3g AC powder, 80°C temperature and 3 hours leaching time. Under

these conditions, Zn dissolution was 84% and pH value of the solution was 0.77.

Table 4 – Results of the reductive leaching tests with ascorbic acid (AA) and activated carbon (AC)

(solid/liquid ratio of 1:20g/mL).

Test No

A B C D

Metal Dissolution (%)

Ascorbic Acid Activated Carbon

H2SO4 con. AA/AC Temp. Time Mn Zn

Mn

Zn

1 -1 -1 -1 -1 50.87 80.16 44.17 71.46

2 1 -1 -1 -1 57,89 84.48 50.08 72.72

3 -1 1 -1 -1 74.53 84.72 49.29 70.49

4 1 1 -1 -1 60.58 86.89 61.12 70.28

5 -1 -1 1 -1 65.83 84.91 66.48 77.24

6 1 -1 1 -1 64.38 89.05 66.79 77.95

7 -1 1 1 -1 74.10 80.10 60.06 73.95

8 1 1 1 -1 75.87 84.91 77.15 79.41

9 -1 -1 -1 1 62.30 81.36 46.56 74.09

10 1 -1 -1 1 62.69 85.79 59.17 80.12

11 -1 1 -1 1 71.69 83.88 59.14 78.79

12 1 1 -1 1 78.78 87.79 74.76 80.12

13 -1 -1 1 1 67.34 87.74 66.11 80.59

14 1 -1 1 1 68.13 89.06 78.94 83.47

15 -1 1 1 1 82.66 86.75 71.57 80.94

16 1 1 1 1 85.97 90.19 86.39 84.08

17 0 0 0 0 65.15 83.38 71.43 83.58

18 0 0 0 0 65.75 83.15 71.04 83.17

19 0 0 0 0 65.25 82.90 71.97 82.47

20 0 0 0 0 65.05 83.20 71.15 82.65

21 0 0 0 0 65.45 83.05

22 0 0 0 0 65.20 82.95

Since AA achieved the maximum Zn and Mn dissolution simultaneously, an optimization study

was carried out for complete dissolutions of valuable metals. AA dosage was changed between 10 and 15

g/L, H2SO4 concentration was changed between 0.2 and 0.7M, leaching temperature was changed

between 20 and 70oC and leaching time was changed between 1 and 5 hours. Full Zn and 99.3% Mn

dissolution were achieved at 0.5M H2SO4, 13 g/L AA, 70oC, 3H and 200 rpm. These samples were used in

the precipitation tests later.

Effect of Guar Meal as a Reductant in Reductive Acid Leaching

In battery recycling, Zn dissolution in H2SO4 solution is not a serious problem. In order to find a

new and cheap reductant to fully dissolve Mn in H2SO4 solution from spent battery powders, GM was used

from 4 g to 12 g. (Figure 4). The recovery/dissolution of Mn increased significantly from 4 g to 10 g GM

addition and then remained constant until 12 g. At 4 g GM dosage, Mn recovery was 68% and at 10 g GM

dosage 100%. Complete Mn dissolution was achieved with 10 g GM addition.

4 6 8 10 12

70

80

90

100

Ma

ng

ane

se

recovery

, %

Guar meal, g

Figure 4 – The effect of GM dosage as a reductant on the dissolution of Mn in H2SO4 leaching.

The effect of leaching time from 1 to 4 hours on Mn dissolution was shown in Figure 5. Mn

dissolution increased with increasing leaching time up to 3 hours and then remained constant. For instance,

recovery of 90.9% was obtained after 1 hour leaching in a 2 M H2SO4 solution using 10 g GM as a

reducing agent. However, under the same condition, when the leaching time was extended to 3 hours,

recovery of Mn was complete.

60 120 180 240

90

92

94

96

98

100

Ma

ng

an

ese

re

co

ve

ry,

%

Leaching time, min.

Figure 5 - The effect of leaching time on the dissolution of Mn in H2SO4 solution in the presence of GM as

a reductant

Comparison of Present Study with the Previous Study Results

Table 5 summarizes the previous and present studies dissolution results for Zn and Mn in the

absence and presence of AA/AC/GM reductants in H2SO4 solutions. There is no problem with the full

dissolution of Zn; but, Mn dissolution is partial in H2SO4 solutions without a reducing agent. In absence of

a reductant, almost full Zn dissolution was possible; however, maximum 40% Mn dissolution, which is

quite low, was achieved in the previous studies. Mn dissolution was changed from 57% to 97% in the

presence of AA in the previous studies (Sayılgan et.al., 2009; Kaya & Kursunoglu, 2011). Present study

achieved almost full dissolutions for both Zn and Mn at 0.5M H2SO4 concentration with 13 g/L AA dosage

and 2M H2SO4 concentration with 10 g/L GM at 3h leaching time and at 70oC leaching temperature. Zn

and Mn dissolutions with AC as a reductant were low and around 85% (Kursunoglu & Kaya, 2013).

Table 5 – Comparison of previous (Sayılgan et.al., 2009) and present studies (Kaya & Kursunoglu, 2012;

Kursunoglu & Kaya 2013) metal dissolutions at optimum conditions

Ref.

Acid Concentration Reductant Time(h)/ Temp.(oC)/

S/L (w/v) (g/mL)/rpm

Metal Dissolution

Zn Mn

Salgado et.al.,

2003

For Zn,H2SO4,

0.2% (v/v)*

without 70oC, 1/10 99.3%

4.5%

El Nadi et.al.,

2007

2M H2SO4 without 2h, 50oC, 1/5 86.6% 6.7%

Ferella et.al.

2008

1.5M H2SO4 without 3h, 80oC, 1/10, 300 rpm 98.9% 19.3%

De Michelis

et.al., 2007

1.1M H2SO4 without 3h, 80oC, 1/5 (20%) 99% 21.3%

De Souza

et.al., 2001

0.7% (v/v) / 0.13M

H2SO4

without 2 h, 50oC, 1/60 100% 30%

Furlani et.al.,

2009

Stoich. H2SO4 without 3h, 90oC, 200 rpm 91.7 31

Veloso et.al.,

2005

0.2-5% (v/v) H2SO4 without 2h, 40-70oC, 1/10-1/50 100 4.5-40

De Souza &

Tenorio, 2004

0.7% (v/v) / 0.13M

H2SO4

without 4h, 50oC, 1/60 100%

40%

Sayılgan et.al.

2010

Stoich. H2SO4

(1.7 M)

Stoich. ascorbic

acid

3h, 45oC, 1/10 103 56.7

Sayılgan et.al.

2012

+30% H2SO4 +30% ascorbic acid 3h, 45oC, 1/10, 200 rpm 99.8% 66.5%

Sayılgan et.al.

2012

Stoich. H2SO4 Stoich. ascorbic

acid

3h, 90oC,1/6.7, 200 rpm 128.8%

97%

Present study 0.5M H2SO4 13 g/L ascorbic

acid

3h, 70 oC, 1/20, 200 rpm 100%

99.3%

Present study 1M H2SO4 3 g activated

carbon

3h, 80 oC, 1/20, 400 rpm 84%

86.4%

Present study 2M H2SO4 10 g guar gum 3h, 70oC, 1/20, 400 rpm 100%

100%

Precipitation

Zn and Mn can be selectively precipitated by adjusting solution pH. Zn is precipitated at pH : 8

and Mn is precipitated at pH : 10. With 3M NaOH, 95.4% Zn and 93.7 Mn and with 3M KOH, 91.6% Zn

and 96.4% Mn were precipitated (Figure 6a and 6b). SEM image of the precipitated Mn(OH)2 by NaOH

showed heterogeneous and fractured structure. SEM-EDX analysis showed presence of large amount of

Mn(OH)2 (Kaya & Kurşunoglu, 2012).

2 4 6 8 10 12

20

40

60

80

100

a

Mn

Zn

Pre

cip

itate

d (%

)

pH

2 4 6 8 10 12

20

40

60

80

100

b

Mn

Zn

Pre

cip

itate

d (

%)

pH

Figure 6 - Precipitation of Zn and Mn with 3M NaOH and 4b) with 3M KOH as a hydroxide

CONCLUSIONS

In this study, a reductive acid leaching was found suitable for the simultaneous recovery of Zn

and Mn from spent mixed Zn-C and alkaline battery powder mixture (d90: -88µm). Before preliminary and

reductive acid leaching, neutral leaching of battery powder with distilled water removed 96% K and 76%

Cl at S/L ratio 1:10 g/mL, 60°C, 200 rpm and 3 h. Preliminary tests showed that dilute H2SO4 gave

complete Zn and concentrated H2SO4 gave complete Mn dissolutions. Three different reductants

(AA/AC/GM) were compared for their effectiveness in the H2SO4 leaching of Mn and Zn from spent

battery powders. By the use of AA/AC/GM as reductants about 84-100% of Zn and 86-100% of Mn were

leached after 3 hours at 70oC temperature. AA and GM were more effective for almost complete leaching

of Mn and Zn under tested acidic conditions than AC as a reductant. The optimum reductive acid leaching

conditions with AA were determined as 3 h leaching time, 70oC leaching temperature, 0.5M H2SO4

concentration, 13 g/L AA dosage, 1/20 g/mL S/L ratio and 200 rpm mixing speed. Under these conditions,

Zn dissolution was full and Mn dissolution was 99.3%. Mn dissolution kinetics showed diffusion

controlled leaching. Full dissolutions of Mn and Zn were achieved at 2M H2SO4 concentration, 10 g GM

dosage at 3h leaching time at 70oC leaching temperature.

Both Mn and Zn precipitation yields increased with increasing solution pH. Almost complete

precipitation of Mn and Zn occurred at pH of about 8 and 10, respectively indicating that Mn and Zn can

be separated through precipitation by adjusting solution pH values. 3M NaOH selectively precipitated

95% of Zn at pH: 8 and 94% of Mn at pH: 10 from leach solution. Under the same conditions, using 3 M

KOH at pH 8; 92% of Zn and at pH 10, 96% of Mn were precipitated. A simple hydrometallurgical flow

sheet (Figure 1) for battery recycling was suggested in this study. But, economic evaluation of the flow

sheet and reductant costs should be made prior to each specific full-scale applications.

Acknowledgements

This work was supported by Research Projects Funding Unit of Eskisehir Osmangazi University

(Project no: BAP 2009/15018) in Eskisehir, Turkey.

REFERENCES

Bernardes, A.M., Espinosa, D.C.R. & Tenorio, J.A.S. (2004). “Recycling of batteries: A review of current

processes and technologies. Journal. of Power Sources, 130, 291-298.

De Michelis, I., Ferella, F., Karakaya, E., Beolchini, F. & Veglio, F., (2007). Recovery of zinc and

manganese from alkaline and zinc-carbon spent batteries”, Journal of Power Sources, 172, 975-

983.

De Souza, C.C.B.M., Oliveira, D.C. & Tenorio, J.A.S. (2001). Characterization of used alkaline batteries

powder and analysis of zinc recovery by acid leaching, Journal of Power Sources, 103, 120-126.

De Souza, C.C.B.M. & Tenorio, J.A.S. (2004). Simultaneous recovery of zinc and manganese dioxide from

household alkaline batteries through hydrometallurgical processing, Journal of Power Sources,

136, 91-196.

El Hazek, M.N., Lasheen, T.A. & Helal, A.S. (2006). Reductive leaching of manganese from low grade

Sinai ore in HCl using H2O2 as reductant, Hydrometallurgy, 84, 187-191.

El-Nadi, Y.A., Daoud, J.A. & Aly, H.F. (2007). Leaching and separation of zinc from the black paste of

spent MnO2-Zn dry cell batteries. Journal of Hazard., 143, 328-334.

Espinosa, D.C.R., Bernardes, A.M. & Tenorio, J.A.S. (2004). “Brazilian policy on battery disposal and its

practical effects on battery recycling”, Journal of Power Sources, 137, 134-139. Ferella, F., Michelis, I.D., Pagnanelli, F., Beolchini, F., Furlani, G. & Navarra, M. (2006). Recovery of

zinc and manganese from spent batteries by different leaching systems”, Acta Metallurgica

Slovaca, 12, 95-104.

Ferella, F., De Michelis, I. & Veglio, F. (2008). Process for the recycling of alkaline and zinc-carbon spent

batteries”, Journal of Power Sources, 183, 805-811.

Froehlich, S. & Sewing, D. (1995). The Batenus Process for recycling mixed battery waste”, Journal of

Power Sources, 57, 27-30.

Furlani, G., Moscardini, E., Pagnanelli, F., Ferella, F., Veglio, F. & Toro, L. (2009). Recovery of

manganese from zinc alkaline batteries by reductive acid leaching using carbohydrates as

reductant, Hydrometallurgy, 99, 115-118.

Gega, J. & Walkowiak, W. L(2011). Leaching of zinc and manganese from used up zinc-carbon batteries

using aqueous sulfuric acid solutions”. Physicochemical Problems of Mineral Processing, 46,

155-162.

Martin, D., Garcia, M.A., Diaz, G. & Falgueras, J. “(2001). A New Zinc Solvent Extraction application:

Spent Domestic Batteries Treatment Plant” In: M. Cox M. Hidalgo and M. Valiente (Eds),

International Solvent Extraction Conference (ISEC’99). Society of Chemical Industry (SCI),

Barcelona, Spain, 201-206.

Mantuano, D.P., Dorella, G., Elias, R.C.A. & Mansur, M.B. (2006). Analysis of a hydrometallurgical route

to recover base metals from spent rechargeable batteries by liquid–liquid extraction with Cyanex

272”, Journal of Power Sources, 159, pp. 1510–1518.

Montgomery, D.C. (2001). Design and Analysis of Experiments, 5nd ed., Wiley, New York.

Mudgil, D., Barak, S. & Khatkar, B.S. (2011). Guar gum: processing, properties and food applications-A

Review, Journal of Food Science and Technology, October.

Kaya, M. & Kursunoglu, S. (2011). A review of the current hydrometallurgical recycling of spent AA and

AAA size Zn-C and alkaline batteries, European Metallurgical Conference (EMC-2011),

Dusseldorf, Germany, Vol. 4, 1417-1436.

Kaya, M. & Kursunoglu, S. (2011a). Recycling of spent AA and AAA size zinc-carbon and alkaline

batteries”. Paper presented at the 9nd

International Conference on Clean Technologies for the

Mining Industry, Santiago, Chile, Published in Proceedings: Ch.4 Waste Disposal, Recycling and

Its Valorisation, Paper 66, April 10-12.

Kaya, M. & Kursunoglu, S. (2012). Dissolution of mixed zinc-carbon and alkaline battery powders in

sulphuric acid using ascorbic/oxalic acid as a reductant, TMS-2012, Orlando, USA, Electronic

Proceedings Volume CD.

Kursunoglu, S. & Kaya, M. (2013). Recovery of manganese from spent batteries using activated carbon

powder as reductant in sulphuric acid solution. Asian Journal of Chemistry. Vol. 25, Issue 4,

1975-1980.

Salgado A.L., Veloso A.M.O., Pereira D.D., Gontijo G.S., Salum A. & Mansur M.B. (2003). Recovery of

zinc and manganese from spent alkaline batteries by liquid-liquid extraction with Cyanex 272.

Journal of Power Sources, 115, 367-37.

Sayılgan E., Kukrer T., Ferella F., Akcil A., Veglio F. & Kitis M. (2009). Reductive leaching of

manganese and zinc from spent alkaline zinc-carbon batteries in acid media”, Hydrometallurgy,

97, 73-79.

Sayılgan, E, Kukrer, T., Yigit, N.O., Civelekoglu, G. & Kitis, M. (2010). Acid leaching and precipitation

of zinc and manganese from spent battery powders using various reductants”, Journal of Hazard.,

173, 37-143.

Salgado, A.L., Veloso, A.M.O., Pereira, D.D., Gontijo, G.S., Salum, A. & Mansur, M.B. (2003),

Recovery of zinc and manganese from spent alkaline batteries by liquid-liquid extraction with

Cyanex 272. Journal of Power Sources, 115, 367-373.

Tacca. A.C.A. & Duarte. M.M.E. (2005). Acid leaching and electrochemical recovery of manganese from

spent alkaline batteries. Paper presented at the 2nd

Mercosur Congress on Chemical Engineering,

Rio de Janerio, Brazil.

Velose, L.R.S ., Rodriguez, L.E.O.C., Ferreira, D.A., Magalhaes, F.S. & Mansur, M.B. (2005).

Development of a hydrometallurgical route for the recovery of zinc and manganese from spent

alkaline batteries. Journal of Power Sources, 152, 295-302.