Document Type : Original Research Paper


Mining engineering department, Faculty of Engineering, University of Birjand, Birjand, Iran


In this work, zinc extraction from an industrial leach solution was investigated by saponified di(2-ethylhexyl)phosphoric acid (D2EHPA). The solution obtained was from a bioleaching process of a low-grade lead-zinc sulfide ore that contained 50 g/L of zinc and 6.3 g/L of iron. The selective and high Zn(II) extraction yield were obtained by modification of D2EHPA in a proposed two-step process. Firstly, a significant amount of iron (87%) was removed as sodium-jarosite via precipitation from the pregnant leaching solution (PLS) prior to zinc extraction, and secondly, the effective parameters involved in zinc extraction including the contact time, saponification degree, type of saponifier, stirring speed, pH, temperature, D2EHPA concentration, and phase ratio (A:O) were investigated. The results obtained showed that 98.4% of zinc could be extracted under the optimum conditions, i.e. 20% D2EHPA, 15% saponification degree, 650 rpm, pH 2, and an A:O ratio of 1:1 at the ambient temperature (25 ± 2 °C) during 90 s; it was 25% higher than using non-saponified D2EHPA under the same conditions. Moreover, while one theoretical step was required for the complete extraction of zinc by saponified D2EHPA, the required number of steps using D2EHPA was about three. Therefore, the advantages of the process would be two-fold: reducing the number of extraction stages and no need for neutralizing the raffinate in every extraction stage.


[1]. Janwong, A., De Wet, K. and Cooper, R. (2016) Impact of silica on cadmium cementation by zinc dust in a zinc SX/EW plant. Minerals & Metallurgical Processing 33 (3), 126-130.
[2]. Mubarok, M.Z., Sukamto, K., Ichlas, Z.T. and Sugiarto, A.T. (2018) Direct sulfuric acid leaching of zinc sulfide concentrate using ozone as oxidant under atmospheric pressure. Minerals & Metallurgical Processing 35 (3), 133-140.
[3]. Javanshir, S., Izadi, H., Tavakoli Mohammadi, M. and Sabeti, H. (2014) A Modified Correlation for Drop Size Distribution in an Experimental Mixer-Settler using Particle Swarm Optimization Algorithm. Separation Science and Technology 49 (4), 553-561.
[4]. Mohammadi, M.R.T., Koleini, S.M.J., Javanshir, S., Abolghasemi, H. and Abdollahy, M. (2015) Solvent extraction of rubidium from gold waste using conventional SX and new CFE methods. Rare Metals 34 (11), 818-828.
[5]. Asadi, T., Azizi, A., Lee, J.-c. and Jahani, M. (2018) Solvent extraction of zinc from sulphate leaching solution of a sulphide-oxide sample using D2EHPA and Cyanex 272. Journal of Dispersion Science and Technology 39 (9), 1328-1334.
[6]. Fukubayashi, H.H., O'Keefe, T.J. and Clinton, W.C. (1974) Effect of Impurities and Additives on the Electrowinning of Zinc, US Bureau of Mines.
[7]. Cole, P.M. and Sole, K.C. (2003) Zinc solvent extraction in the process industries. Mineral Processing and Extractive Metallurgy Review 24 (2), 91-137.
[8]. Devi, N., Nathsarma, K. and Chakravortty, V. (1997) Liquid-liquid extraction of manganese (II) with binary mixtures of sodium salts of D2EHPA, PC 88A and Cyanex 272. Solvent Extr. Res. Dev. Jpn 4, 117-128.
[9]. Avila, M., Perez, G. and Valiente, M. (2011) Extractant and solvent selection to recover zinc from a mining effluent. Solvent Extraction and Ion Exchange 29 (3), 384-397.
[10]. Chaudhury, G.R., Bhaskar Sarma, P.V.R. and Sahoo, P.K. (1994) Processing of zinc leach liquor in mixer-settler units using D2EHPA — A case study. Mining, Metallurgy & Exploration 11 (4), 188-191.
[11]. Li, X.-h., Ai, X.-b., He, L., Ji, S.-s., Hu, M., Ding, J.-n. and Li, F. (2017) Solvent extraction separate of zinc and cadmium from magnesium and calcium in sulfuric acid medium by mixing extractants. Journal of Central South University 24 (10), 2253-2259.
[12]. Barkat, D., Kameche, M., Tayeb, A., Benabdellah, T. and Derriche, Z. (2004) Ionic strength effect on the liquid–liquid extraction of zinc (II) and cadmium (II) from sulphate medium by 1-phenyl-3-methyl-4-benzoylpyrazol-5-one in chloroform. Physics and Chemistry of Liquids 42 (1), 53-61.
[13]. Hu, J., Chen, Q., Yang, X., Hu, F., Hu, H. and Yin, Z. (2012) Extraction of zinc from ammoniacal solution with β-diketone: A comparative study of solvents used. Separation and purification technology 87, 15-21.
[14]. Hernández, L., Hernández, L., Legorreta, F. and Avila-Rodriguez, M., Study of extraction of Zn (II) from ammoniacal media with ionic liquids, IOP Conference Series: Materials Science and Engineering, IOP Publishing, 2013, p. 012020.
[15]. Mcdonald, C.W. and Lin, T.-S. (1975) Solvent extraction studies of zinc and cadmium with Aliquat 336-S in aqueous chloride solutions. Separation Science 10 (4), 499-505.
[16]. HU, J.-g., CHEN, Q.-y., HU, H.-p. and YIN, Z.-l. (2012) Synergistic extraction of zinc from ammoniacal solutions using β-diketone mixed with CYANEX923 or LIX84I. Transactions of Nonferrous Metals Society of China 22 (5), 1217-1223.
[17]. Reddy, B.R. and Bhaskara Sarma, P.V.R. (2001) Separation and recovery of cobalt and nickel from sulfate solutions of Indian Ocean nodules using Cyanex 272. Mining, Metallurgy & Exploration 18 (3), 172-176.
[18]. Parus, A., Wieszczycka, K. and Olszanowski, A. (2012) Zinc (II) ions removal from chloride solutions by hydrophobic alkyl-pyridyl ketoximes. Separation Science and Technology 48 (2), 319-327.
[19]. Fleitlikh, I.Y., Pashkov, G., Grigorieva, N., Logutenko, O. and Kopanyov, A. (2014) Zinc extraction from sulfate–chloride solutions with mixtures of a trialkyl amine and organic acids. Hydrometallurgy 149, 110-117.
[20]. Begum, N., Bari, F., Jamaludin, S.B. and Hussin, K. (2012) Solvent extraction of copper, nickel and zinc by Cyanex 272. International Journal of Physical Sciences 7 (22), 2905-2910.
[21]. Daryabor, M., Ahmadi, A. and Zilouei, H. (2017) Solvent extraction of cadmium and zinc from sulphate solutions: Comparison of mechanical agitation and ultrasonic irradiation. Ultrasonics Sonochemistry 34, 931-937.
[22]. Deep, A. and de Carvalho, J.M. (2008) Review on the recent developments in the solvent extraction of zinc. Solvent Extraction and Ion Exchange 26 (4), 375-404.
[23]. Sun, M., Liu, S., Zhang, Y., Liu, M., Yi, X. and Hu, J. (2019) Insights into the saponification process of di (2-ethylhexyl) phosphoric acid extractant: Thermodynamics and structural aspects. Journal of Molecular Liquids 280, 252-258.
[24]. Cole, P.M. and Sole, K.C. (2002) Solvent extraction in the primary and secondary processing of zinc. Journal of the South African Institute of Mining and Metallurgy 102 (8), 451-456.
[25]. Vahidi, E., Rashchi, F. and Moradkhani, D. (2009) Recovery of zinc from an industrial zinc leach residue by solvent extraction using D2EHPA. Minerals Engineering 22 (2), 204-206.
[26]. Jafari, H., Abdollahi, H., Gharabaghi, M. and Balesini, A.A. (2018) Solvent extraction of zinc from synthetic Zn-Cd-Mn chloride solution using D2EHPA: Optimization and thermodynamic studies. Separation and Purification Technology 197, 210-219.
[27]. Long, H.-z., Chai, L.-y., Qin, W.-q. and Tang, S.-h. (2010) Solvent extraction of zinc from zinc sulfate solution. Journal of Central South University of Technology 17 (4), 760-764.
[28]. Zielinski, S., Buca, M. and Famulski, M. (1998) Precipitation–stripping processes for heavy metals. Hydrometallurgy 48 (3), 253-263.
[29]. Lan, Z.-y., Hu, Y.-h., Liu, J.-s. and Wang, J. (2005) Solvent extraction of copper and zinc from bioleaching solutions with LIX984 and D2EHPA. Journal of Central South University of Technology 12 (1), 45-49.
[30]. Mellah, A. and Benachour, D. (2006) The solvent extraction of zinc and cadmium from phosphoric acid solution by di-2-ethyl hexyl phosphoric acid in kerosene diluent. Chemical Engineering and Processing: Process Intensification 45 (8), 684-690.
[31]. Owusu, G. (1998) Selective extractions of Zn and Cd from Zn-Cd-Co-Ni sulphate solution using di-2-ethylhexyl phosphoric acid extractant. Hydrometallurgy 47 (2-3), 205-215.
[32]. Silva, J.E.d., Paiva, A., Soares, D., Labrincha, A. and Castro, F. (2005) Solvent extraction applied to the recovery of heavy metals from galvanic sludge. Journal of Hazardous Materials 120 (1-3), 113-118.
[33]. Balesini, A., Razavizadeh, H. and Zakeri, A. (2011) Solvent Extraction of Zinc from Acidic Solution Obtained from Cold Purification Filter Cake of Angouran Mine Concentrate Using D2EHPA. Iranian Journal of Chemical Engineering 8 (3), 43-47.
[34]. Pereira, D.D., Rocha, S.D.F. and Mansur, M.B. (2007) Recovery of zinc sulphate from industrial effluents by liquid–liquid extraction using D2EHPA (di-2-ethylhexyl phosphoric acid). Separation and purification technology 53 (1), 89-96.
[35]. Li, Y., Hu, J., Fu, M., Tang, J., Dong, L. and Liu, S. (2016) Investigation of intermolecular interactions of mixed extractants of quaternary phosphonium or ammonium chlorides and bis (2, 4, 4-ethylhexyl) phosphoric acid for metal separation. RSC advances 6 (62), 56772-56779.
[36]. Sun, W., Lin, H., Zhai, Y., Cao, L., Leng, K. and Xing, L. (2015) Separation, Purification, and Identification of (3S, 3′ S)-trans-Astaxanthin from Haematococcus pluvialis. Separation Science and Technology 50 (9), 1377-1383.
[37]. Vechpanich, J. and Shotipruk, A. (2010) Recovery of free lutein from Tagetes erecta: determination of suitable saponification and crystallization conditions. Separation Science and Technology 46 (2), 265-271.
[38]. Jiang, F., Zhang, L., Jian, J., Xia, H., Ju, S. and Peng, J., Microfluidic Solvent Extraction of Zinc from Low Concentration Sulfate Solution Using D2EHPA, TMS Annual Meeting & Exhibition, Springer, 2018, pp. 325-333.
[39]. Nathsarma, K. and Devi, N. (2006) Separation of Zn (II) and Mn (II) from sulphate solutions using sodium salts of D2EHPA, PC88A and Cyanex 272. Hydrometallurgy 84 (3-4), 149-154.
[40]. Potuzak, M. (2001) Potassium dichromate Potentiometric Titration of Iron in natural magmas. LMU Intrainstitute Manual.
[41]. Habashi, F. (1999) A textbook of hydrometallurgy, Métallurgie Extractive.
[42]. Atkins, P.W., De Paula, J. and Keeler, J. (2018) Atkins' physical chemistry, Oxford university press.
[43]. Wang, X., Zhu, Y. and Jiao, R. (2001) Separation of Am from macro amount of lanthanides by a countercurrent multistage extraction with purified Cyanex 301 and TBP. Solvent Extraction and Ion Exchange 19 (6), 1007-1015.
[44]. Wang, X., Zhu, Y. and Jiao, R. (2002) Separation of Am from lanthanides by a synergistic mixture of purified Cyanex 301 and TBP. Journal of radioanalytical and nuclear chemistry 251 (3), 487-492.
[45]. Udachan, I. and Sahoo, A. (2014) A study of parameters affecting the solvent extraction of lactic acid from fermentation broth. Brazilian Journal of Chemical Engineering 31 (3), 821-827.
[46]. Javanshir, S., Abdollahy, M., Abolghasemi, H. and Darban, A.K. (2011) Kinetics of Au (III) extraction by DBC from hydrochloric solution using Lewis cell. International Journal of Mineral Processing 98 (1-2), 42-47.
[47]. De, A.K., Khopkar, S.M. and Chalmers, R.A. (1970) SOLVENT EXTRACTION OF METALS, 1970; Originating Research Org. not identified.
[48]. Keng, X., Jiankang, W., Yixin, H. and Renman, R. (2008) Selective separation of Cu (II), Zn (II), and Cd (II) by solvent extraction. Rare Metals 27 (3), 228-232.
[49]. Fatmehsari, D.H., Darvishi, D., Etemadi, S., Hollagh, A.E., Alamdari, E.K. and Salardini, A. (2009) Interaction between TBP and D2EHPA during Zn, Cd, Mn, Cu, Co and Ni solvent extraction: A thermodynamic and empirical approach. Hydrometallurgy 98 (1-2), 143-147.
[50]. Zhang, Y., Zhang, T.-a., Lv, G., Zhang, G., Liu, Y. and Zhang, W. (2016) Synergistic extraction of vanadium (IV) in sulfuric acid media using a mixture of D2EHPA and EHEHPA. Hydrometallurgy 166, 87-93.
[51]. Song, Y., Zhao, Z. and He, L. (2020) Lithium recovery from Li3PO4 leaching liquor: Solvent extraction mechanism of saponified D2EHPA system. Separation and Purification Technology 249, 117161.
[52]. Jin, Y., Ma, Y., Weng, Y., Jia, X. and Li, J. (2014) Solvent extraction of Fe3+ from the hydrochloric acid route phosphoric acid by D2EHPA in kerosene. Journal of Industrial and Engineering Chemistry 20 (5), 3446-3452.
[53]. Sainz-Diaz, C., Klocker, H., Marr, R. and Bart, H.-J. (1996) New approach in the modelling of the extraction equilibrium of zinc with bis-(2-ethylhexyl) phosphoric acid. Hydrometallurgy 42 (1), 1-11.
[54]. Pavia, D.L., Lampman, G.M., Kriz, G.S. and Vyvyan, J.A. (2008) Introduction to spectroscopy, Cengage Learning.
[55]. Darvishi, D., Haghshenas, D., Alamdari, E.K., Sadrnezhaad, S. and Halali, M. (2005) Synergistic effect of Cyanex 272 and Cyanex 302 on separation of cobalt and nickel by D2EHPA. Hydrometallurgy 77 (3-4), 227-238.