APPLICATION OF LIXIVIATION-CUM-SOLVENT EXTRACTION TO THE BENEFICIATION
OF SPENT ZINC-CARBON BATTERIES.
Assoc. Prof. Folahan A. ADEKOLA(+) and Dr. Alafara A. BABA (+)
Department of Chemistry, P.M.B. 1515, University of Ilorin, Ilorin – Nigeria.
(+) Corresponding Authors:
E-mail: fadekola@unilorin.edu.ng (F. A. Adekola)
alafara@unilorin.edu.ng (A. A. Baba)
Tel: +2348067332320, +2348035010302
Abstract
The techniques of chemical leaching and solvent extraction using Cyanex®272 have been applied
to the recovery of valuable zinc (II) from spent zinc-carbon batteries in hydrochloric acid. The
experimental data for the dissolution process have been analyzed and were found to follow the shrinking
core model for mixed control reaction with surface chemical reaction as the rate controlling step. About
90.3%, dissolution was achieved with 4m HCl solution at 800C with 0.050 – 0.06 3mm particle size within
120 minutes at 360rpm. Activation energy value of 22.78kJ/mol and a reaction order of 0.74 with respect
to H= ion concentration were obtained for the dissolution process. An extraction yield of 94.23% zinc (II)
by 0.032M Cyanex®272 in kerosene was obtained from initial 10g/L spent battery leach liquor at 25±20C
and at optimal stirring time of 25 minutes Iron has been effectively separated by precipitation prior to
extraction by ammoniacal solution at pH 3.5, while lead and other trace elements were firstly separated
from zinc (II) and total iron by cementation prior to iron removal and zinc (II) extraction. Finally, the
stripping study showed that 0.1M HCl led to the stripping of about 95% of zinc (II) from the organic phase.
Key words: Lixiviation, Solvent extraction, Zn(II) recovery, Zinc-carbon
batteries.
Introduction:
The world demand for metals is progressively increasing, while primary resources are being
depleted. With the constraints raised by law and related legislation assigned to protect the environment
from hazardous wastes in the world, it becomes more and more important to partly satisfy such world
demand through recovery of metals of concern from secondary sources including Zinc-Carbon batteries (Li
et al, 2009; Rabah et al, 2008).
Disposal of spent batteries is of major concern to the environment in terms of heavy metals
content contained therein. According to the battery market evolution in 2003, the total portable battery
weight in the East and West Europe was estimated to be 164, 000 tons, of which Zinc-carbon and alkaline
batteries constituted 30.5% and 60.3%, respectively (Baba, et al, 2010).
1
Zinc batteries could therefore be considered as a valuable one of the secondary raw materials for
the recovery of zinc. To this end, a world shortage of 432, 000 tons of zinc concentrates has been reported
in 2005 and the zinc price attained a record value of about & 2500/tons (Ferella, et al, 2006)
At present, there are basically two main methods employed world wide in metal production from
secondary sources. The most important one is the conventional pyrometallurgical method, which may not
be popular in a developing economy due to high-energy requirement (Baba, et al, 2009; Rotuska and
Chmielewski, 2008). The hydrometallurgical processes are more environmentally suitable and economical
to treat even low zinc containing materials on small scale. It consists of crushing, leaching (non-oxidative
leaching, atmospheric leaching and pressure leaching), solvent extraction and electrowinning (Rotuska and
Chmielewski, 2008).
In recent years, the acid leaching of batteries are amenable due to the availability of materials for
construction with improved resistance to chloride attack and substantially faster dissolution rates and
relative cheap in terms of cost are among other reasons why HCl is preferred to other acids such as H2SO4
and HNO3 for leaching purposes (Zuo-mei, et al, 1984). In the publicly available literature, there is a
substantial amount of data on the extraction of Zn(II) from acidic leachates using organophosphorus
extractants (Alguacil, et al, 1992; Regel-Rosocka, et al, 2003).
Therefore, the present study is developed to carry out a complete investigation involving both acid
leaching and solvent extraction of Zinc(II) from the spent Zinc-carbon batteries that have constituted a
major portion of the hazardous wastes in sub-saharan Africa (Tetsopgang, et al, 2007) by Cyanex®272.
Experimental.
Spent Zinc-Carbon batteries, the cheapest and the most popular brand (Tiger Head typemanufactured in China) in the Nigerian market were collected and used for this study. The sample
dismantling, chemical leaching and Zinc(II) recovery procedure from the leach liquor are detailed
elsewhere (Baba, et al, 2009). The Zinc(II) recovery was done by solvent extraction technique with
Cyanex®272. After equilibration and phase separation, the concentration of Zn left in the aqueous phase
was analysed. The concentration of the metal ion extracted into the organic phase was caculated by
difference. (Baba, et al, 2009). Prior to extraction of Zn and in order to avoid interference, iron has been
previously removed by precipitation in ammoniacal solution at pH 3.5 with conc. NH3 solution after
moderate stirring (Daoud, et al, 2006). Lead and other trace elements from the leach liquor were
successfully separated from Zinc by cementation with pure Zinc metal (Baba, et al, 2004). Finally, the
stripping of Zinc from organic phase was done by 0.1M HCl (Baba, 2008).
Results, Discussion and conclusions:
The results of the quantitative leaching of the powdered Zinc-Carbon batteries by hydrochloric
acid showed that the dissolution rates are significantly influenced by system temperature and concentration
of the acid solutions. The experimental data for the dissolution rates have been analysed and were found to
2
follow the shrinking core model for mixed control reaction with surface chemical reaction as the
controlling step.
Finally, a hydrometallurgical scheme for Zinc and lead recovery from spent Zinc-carbon batteries
by hydrochloric acid leaching consisting of 594.3mg/L Zn, 70.4mg/L Pb and 98.74mg/L Fe as major
constituents by Cyanex®272 is summarized in Fig. 1.
3
Spent zinc-carbon battery collection
and sample preparation (crushing,
sorting, pulverizing)
Leaching in HCl media
4M HCl at 360rpm; 3.0; 80oC
Composition:
Zn: 594.3mg/L; Pb: 70.40mg/L;
Fe: 98.74mg/L
Other elements: Ag, Mn, Cu are present
in traces.
Leachate
Zn metal granules; 25±2oC
Cementation
Composition:
Zn: 622.59mg/L; Pb: <2mg/L; Fe: 95.66mg/L
Efficiency of cementation = 98%
Ammoniacal solution, pH 3.5; 25±2oC
Re-use, n≤3
Iron separation
Composition:
Zn: 604.27mg/L; Fe: <1mg/L
Iron removal efficiency = 98%
0.032M Cyanex®272; pH 3.0;
Stirring rate = 25min; 25±2oC
Solvent extraction of
Zinc(II)
Cyanex®272
regenerated
Zn-Cyanex®272: 569.38mg/L;
Extraction efficiency = 94.23%
0.1M HCl; 25oC
Zinc(II) stripping
Zn-aqueous: 507.41mg/L;
Recovery efficiency = 95.48%
Zn(II) in 0.1M HCl
Fig. 1 Hydrometallurgical scheme for zinc and lead recovery from spent zinc-carbon batteries
in Hydrochloric acid4medium by Cyanex®272..
Acknowledgements:
The authors are grateful to Dr. Oliver Rouher and Mrs. Christine Salomon of Cytec Industries,
Rungis Cedex, France for providing the Cyanex®272 used for this study. A. A. Baba also appreciates the
University of Ilorin, Ilorin-Nigeria for the 2005/2006 Staff Development Award.
References:
Alguacil, F.J., Cobo, A., and Caravaca, C. Study of the extraction of Zinc(II)
In aqueous chloride media by Cyanex 302. Hydrometallurgy, 31, 163174, 1992.
Baba, A. A., Adekola, F. A. and Bale, R. B. Development of a combined
pyro- and hydro-metallurgical route to treat spent zinc-carbon
batteries. Journal of Hazardous Materials, 171, 838-844, 2009.
Baba, A.A., Adekola, F. A. and Ewuloye, G.D. Leaching of lead from spent
motorcycle battery in hydrochloric acid part 1: Dissolution kinetics. Acta Metallurgical Slovaca,
16(4), 88-93, 2010.
Baba, A.A., Adekola, F.A. and Mesubi, M.A. Solvent extraction of Zinc
with Triphenylphosphite from a Nigerian sphalerite in hydrochloric acid. J. Sci., Isl. Rep., Iran.
14(1), 33-37, 2004.
Baba, A.A. Recovery of zinc and lead from sphalerite, galena and waste
materials by hydrometallurgical treatment. Ph.D. Thesis, Chemistry Department, University of
Ilorin, Ilorin-Nigeria, 675pp., 2008.
Daoud, J.A., Ali, A.M.I. and Ahmad, J. A. CYANEX 272 for the extraction
and recovery of Zinc from aqueous waste solution using a mixer-settler unit. Sep. & Purification
Technol., 47, 135-140, 2006.
Ferella, F., Michelis, I.D., Pagnanelli, F., Beokhini, F., Furlani, G., Navarra,
M., Vegilio, F. and Tovo, L. Recovery of Zinc and manganese from spent batteries by different
leaching systems. Acta Metallurgical Slovaca, 12, 95-104, 2006.
Li, J., Li, X., Lu, Q., Wang, Z., Zheng, J., Wu, L. and Zhang, L. Study of
extraction and purification of Ni, Co and Mn From spent battery material. Hydrometallurgy,
HDROM-03021, 6pp. 2009.
Rabah, M.A., Farghaly, F.E. and Abd-El-Motaleb, M.A. Recovery of nickel,
cobalt and some salts from spent Ni-MH batteries. Waste Management, 28(7), 1159-1167, 2008.
Regel-Rosocka, M., Miesiac, R., Cierpiszewski, I., Mishowov, K., Alejski,
A. and Symanowski, J. Recovery of Zinc(II) from spent hydrochloric acid solutions from Zinc
hot-dip galvanizing plants. A Proceeding Hydrometallurgy 2003 Mineral Soc. Am. Short Course
Notes, 1577-1591, 2003.
Rotuska, K. and Chmielewski, T. Growing role of solvent extraction in
5
copper ores processing, Physiocochemical Problems of Min. Processing, 42, 29-36, 2008.
Tetsopgang, S. and Kuepono, G. Quantification and Characterization of
discarded batteries in Yaounde from the perspective of health, safety and environment protection.
Resources, Conserv. Recycling, 52(8-9), 1077-1081, 2007.
Zno-mei, G., Warren, W. and Henein, H. Reaction kinetics of the ferric
chloride leaching of sphalerite- an experimental study. Met. Trans. B., 15B, 5-12, 1984.
6